Re: Am I holding on to the head here ?
I am not sure exactly how preduce differs from normal reduce, but reduce is not a lazy operation, so it will result in the realization of a lazy seq passed to it. On Sun, Feb 8, 2009 at 2:13 PM, Jeffrey Straszheim straszheimjeff...@gmail.com wrote: I have this piece of code: (defn- run-work-elements-in-parallel Runs a group of work elements in parallel. Returns an extended database. [elements database] (assert (set elements)) (let [[rec simp] (separate :recursive elements) results-simp (pmap #(run-simple-work-element % database) simp) results-rec (map #(run-recursive-work-element % database) rec) results (concat results-simp results-rec)] (preduce union (cons database results The exact details aren't important. The let bindings results-simp, results-rec, and results are each a lazy stream. They can get quite large. Assuming preduce can iterate over them, is binding them in the let statement stopping them from getting garbage collected? If so, is the best solution to wrap them in a (fn [] ...) and then use them like (results)? Thanks -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: anonymous functions
fn has an implicit (do ...) #(do ...) behaves the same way. #(a b c) expands to (fn [] (a b c)) if you put in multiple forms you get #((a b)(c d)) expands to (fn [] ((a b) (c d))) note the (a b) in the operator position. On Tue, Feb 10, 2009 at 8:09 PM, Mark Volkmann r.mark.volkm...@gmail.com wrote: Just checking my understanding of the rules for writing anonymous functions ... (fn [args] ...) allows any number of expressions in its body. #(...) only allows a single expression in its body, correct? Why the difference? -- R. Mark Volkmann Object Computing, Inc. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: alternate syntax
You might be interested in my pet macro: pl http://github.com/hiredman/odds-and-ends/blob/8a84e6ddbad9d71f714ba16c3e1239633228a7eb/functional.clj#L94 it does transformations on code using zippers. for example: (pl inc $ inc $ 0) expands to (inc (inc 2)) pl is just a toy but it might be worth looking at. On Mon, Feb 23, 2009 at 7:42 AM, Mark Volkmann r.mark.volkm...@gmail.com wrote: I have an idea I'd like to float to see if there are reasons why it's a bad idea. What if Clojure had an alternate surface syntax that was translated into standard Clojure syntax by a kind of preprocessor? Many people that don't like Lisp dialects don't like them because of the parentheses. I'm trying to address that. Here's a simple example of valid Clojure code. (defn pig-latin [word] (let [first-letter (first word)] (if (.contains aeiou (str first-letter)) (str word ay) (str (subs word 1) first-letter ay (println (pig-latin red)) (println (pig-latin orange)) Here's what that same code would look like in my alternate syntax. defn pig-latin [word] let [first-letter (first word)] if .contains aeiou (str first-letter) str word ay str (subs word 1) first-letter ay println (pig-latin red) println (pig-latin orange) The rules for turning this into standard Clojure syntax are pretty simple. 1) If a line is indented farther than the previous one, it is part of the previous line. 2) If a line doesn't start with a (, then add one. 3) If the next line is indented less than this one, add the appropriate number of )'s at the end. 4) If the first token on a line is if and the first non-whitespace character after it is not ( then assume the rest of the line is the condition and wrap it in ( ). A translation from standard Clojure syntax to this alternate form should also be possible. Is this a bad idea? -- R. Mark Volkmann Object Computing, Inc. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Flatten a list
filter, http://clojure.org/api#filter On Tue, Feb 24, 2009 at 7:38 PM, Sean francoisdev...@gmail.com wrote: I've got the following list (:a nil nil :b :a) I want to call a nil-killer function, and get the following list (:a :b :a) How do I go about this? Could someone post a quick example? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Extensive use of let?
You should look at - it lest you take (op3 (op2 (op1 input))) and write it as (- input op1 op2 op3) there is also comp which composes functions, and partial for partial application. some example comp usage: http://github.com/hiredman/clojurebot/blob/297e266b0badf0f301a556e95771b940a80016e7/hiredman/clojurebot/tweet.clj#L11 On Wed, Feb 25, 2009 at 12:57 PM, levand luke.vanderh...@gmail.com wrote: Recently, in my code, I have been struggling with which of the two equivalent forms is, in a general sense, better. (defn my-fn1 [input] (let [value1 (op1 input) value2 (op2 input) value3 (op4 value1 value2)] (op5 value3))) (defn my-fn2 [input] (op5 (op4 (op1 input) (op2 input Now, the second is definitely cleaner and more elegant, besides being smaller, which is a non-trivial benefit when I have a fair amount of code to page through. However, if I've been away from the code awhile, it's much easier to come back determine what the code is doing when its written the first way, especially when it uses descriptive names. An operation that is impenetrable when written in nested form can become quite simple when each step is broken down and labeled. Clojure is my first Lisp - should I just stick with the second form until I learn to see through the nested s-expressions? It's not that I'm trying to make my code more imperative - Although I come from a Java background, I love functional programming, and it is a delight to see how much I can do without side-effects. But I do miss the self-documentation that well-named variables can provide. Any thoughts? Also, is there any performance degradation from the first way, or can the compiler optimize it away? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: transposing a small java class in clojure
I don't know how many arguments the method you are overriding with
onLogin takes, but the function you define should take one more
argument then the method you are overiding, the first argument being
an explicit reference to an instance
On Tue, Mar 10, 2009 at 12:16 PM, rb raphi...@gmail.com wrote:
HI Chris,
thanks for your response, and I'll update the code as you suggest.
However, I actually have problems even when the -onLogin function is
empty, returns nil, or returns FtpletResult/DEFAULT. It seems it
causes trouble once it's defined.
I'll post an update tomorrow
Raphaël
On Mar 10, 6:50 pm, chris cnuern...@gmail.com wrote:
I can see one possible difference, depending on how you are loading
the code into the ftp server.
In your clojure example you are accessing the logger through a top-
level define. I believe this will run *during the file loading
process* as static code.
In your working java example, you aren't accessing the logger until
the actual onLogin function is called.
If the logger is in an odd state (like null) or god forbid the runtime
sets up the logger just before it calls into your function then you
may get different results. I would recommend calling the getlogger
call in the function perhaps; change the 'def logger' to 'defn logger
[]' and work out the resulting details. This would make the clojure
example a little closer to your java example and at least eliminate
one possible problem.
Chris
On Mar 10, 7:35 am, rb raphi...@gmail.com wrote:
Hi,
I'm experimenting withhttp://mina.apache.org/ftpserver
I have written a small java class that gets used by the ftp server,
and am trying to transpose it to clojure, but unsuccessfully until
now
The class generated with clojure is detected and used by the server,
but the code of the method implemented is not run, and even worse, the
ftp server isn't functional anymore (though I don't see any exception
raised).
Does anyone have an idea about what I'm doing wrong?
Thanks
Raphaël
Here's the java code:
package com.raphinou;
import java.io.IOException;
import org.apache.ftpserver.*;
import org.apache.ftpserver.ftplet.*;
public class Ftplet extends DefaultFtplet {
public FtpletResult onLogin(FtpSession session, FtpRequest
request)
throws FtpException, IOException {
java.util.logging.Logger logger=
java.util.logging.Logger.getLogger(com.raphinou);
logger.addHandler( new java.util.logging.FileHandler(/tmp/
ftp.log));
logger.severe(Logging in!!);
return FtpletResult.DEFAULT;
}
}
and here's the clojure code:
(ns com.raphinou.ftplet
(:gen-class :name com.raphinou.Ftplet
:extends org.apache.ftpserver.ftplet.DefaultFtplet)
(:import [org.apache.ftpserver.ftplet DefaultFtpReply
FtpletResult]))
(def logger (java.util.logging.Logger/getLogger com.raphinou))
(.addHandler logger (java.util.logging.FileHandler. /tmp/ftp.log))
(defn -onLogin [session request]
(.severe logger Logging in, clj)
FtpletResult/DEFAULT)
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Re: Request: Can clojure.contrib.walk provide a reduce type operation?
if your walk pushes the items into a Queue, you can just reduce across the Queue On Wed, Mar 11, 2009 at 9:24 AM, Jeffrey Straszheim straszheimjeff...@gmail.com wrote: Currently the clojure.contrib.walk code provides a nice way to perform a depth first map operation on trees. However, I need to fold across a tree. It would be nice if walk provided this. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Slash mystery
this came up on irc starting: http://clojure-log.n01se.net/date/2009-02-18.html#23:49 and the solution: http://clojure-log.n01se.net/date/2009-02-19.html#0:30 On Wed, Mar 18, 2009 at 11:03 AM, Konrad Hinsen konrad.hin...@laposte.net wrote: Consider the following session: user= / #core$_SLASH___3331 clojure.core$_slash___3...@7a916b user= clojure.core// #core$_SLASH___3331 clojure.core$_slash___3...@7a916b user= (ns-unmap *ns* '/) nil user= / java.lang.Exception: Unable to resolve symbol: / in this context (NO_SOURCE_FILE:0) user= (defn / [a b] (clojure.core// a b)) #'user// user= / #user$_SLASH___1401 user$_slash___1...@37a91a user= user// java.lang.Exception: Invalid token: user// Why is user// an invalid token, whereas clojure.core// works perfectly well? Konrad. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Slash mystery
Symbols starting and ending with . are reserved. see http://clojure.org/reader the section on Symbols On Wed, Mar 18, 2009 at 12:58 PM, Michael Wood esiot...@gmail.com wrote: On Wed, Mar 18, 2009 at 8:22 PM, Kevin Downey redc...@gmail.com wrote: this came up on irc starting: http://clojure-log.n01se.net/date/2009-02-18.html#23:49 and the solution: http://clojure-log.n01se.net/date/2009-02-19.html#0:30 Interesting. I noticed something similar the other day: user= (defn ... [] (print 'something)) #'user/... user= (...) java.lang.IllegalArgumentException: Malformed member expression, expecting (.member target ...) (NO_SOURCE_FILE:4) user= But I suppose that's a reader macro thing? -- Michael Wood esiot...@gmail.com -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Help with the dot operator special form
you want defmacro not definline. the result of a macro is a data structure. that data structure is then evaluated in place of the call to the macro. definline (I think?) behaves similar to a function, so if it returns a data structure, you just get that data structure (the data structure is not then evaluated) On Sat, Mar 21, 2009 at 6:04 PM, David Nolen dnolen.li...@gmail.com wrote: I'm wondering if it's possible to create a Clojure function that does what the dot operator does. It seems like this would be possible with definline but I'm unable to get this to work or figure it out. For example I want to be able write something like the following: (dot Hello world (list 'substring 1 2)) Trying to use definline like this: (definline dot [obj member-exp] `(. ~obj (~...@member-expr))) Simply throws an error. I don't need variable arity, I will always pass an instance or class following by a list representing the member expression. Is this impossible? It seems like this would be generally useful to allow variable method calling on Java objects. As to why I want it to implement this, it would be far simpler to support Java interop from clj-cont if the dot operator could be expressed as a Clojure function. Thanks! David -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Mapping a function over a map's values
(defn mapmap [fn m]
(into {} (map #(vector (first %) (fn (second %))) m)))
On Sun, Mar 22, 2009 at 1:10 PM, Jon Nadal jon.na...@gmail.com wrote:
I often need to map a function over the values of a map while
preserving keys--something like:
[code]
(defn mapmap [fn m]
(let [k (keys m)
v (map fn (vals m))]
(zipmap k v)))
(mapmap inc {:a 0, :b 1})
[/code]
Is there a more concise way to do this in Clojure? If not, is this
something that might be worth putting in the contrib?
-Jon
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Re: introspect namespace ?
(.toString *ns*) On Sun, Apr 5, 2009 at 12:39 PM, Stephen C. Gilardi squee...@mac.com wrote: On Apr 5, 2009, at 3:23 PM, dysinger wrote: I need coffee - too many typos. I meant to say I am trying to avoid _typing_ 'x.y.z' twice (str (the-ns 'user)) is is even more human-error prone than just typing user. I was look for a way to introspect ns (DRY up the Logger/getLogger call). In java you could just Logger.getLogger(this.getClass().getName ()) or something so you are not prone to typos and it's refactor- friendly. If you want the name of the current namespace as a string, here's one way: (- *ns* ns-name name) --Steve -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Question about metadata on map keys
I think you misunderstand, I don't think he is expecting to being able
to use :foo as a key twice with different metadata.
I think he wants something like:
(def x {[:a] 1 [:b] 2})
then
(meta (first (keys (assoc x (with-meta [:a] {:x 1}) 2
;(- (assoc x (with-meta [:a] {:x 1})) keys first meta)
would be {:x 1}, instead of nil
On Fri, Apr 10, 2009 at 7:09 AM, Stuart Sierra
the.stuart.sie...@gmail.com wrote:
On Apr 10, 12:14 am, Jason Wolfe jawo...@berkeley.edu wrote:
...
Namely, if a map already contains a given key, when you attempt to
assoc in a version of the key with new metadata this is not recorded.
It seems that the map always retains the original key:
...
Is this desired behavior? If so, is there a better way to change the
metadata on a key than first dissoc-ing it out and then assoc-ing it
back in again with new metadata?
Probably this is expected, since metadata is defined not to affect
equality, and maps rely on equality semantics. I would recommend
against storing metadata on map keys. In general, if the metadata
matters for the value of an object, then it shouldn't be metadata.
Some alternatives: 1) put the information directly in the map values;
2) store metadata on the map values; 3) use maps as keys.
-Stuart Sierra
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Re: java.lang.String cannot be cast to [Ljava.lang.CharSequence;
I would be interested in seeing a full stack trace and some pastbined code. there are no clojure strings, just java strings, and java strings are charsequences. On Thu, Apr 16, 2009 at 11:25 AM, prhlava prhl...@googlemail.com wrote: Hello, I am trying to use a java library ( http://code.google.com/p/webdriver/ ), the method I need to call has signature: sendKeys(java.lang.CharSequence... keysToSend) If I give it a clojure string, the cannot be cast message appears in the stack trace. I have tried explicit (cast java.lang.CharSequence my-string) but the cast does only compare AFAIK. Is there a way to give the library what it wants from Clojure? Kind regards, Vlad -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: IFn?
ifn? returns true for things that implement clojure.lang.IFn, IFn is the interface for things that can be put in the operator position in a s-expr: functions vectors maps sets keywords symbols ...? fn? returns true for just functions On Sat, Apr 18, 2009 at 9:37 PM, tmountain tinymount...@gmail.com wrote: Sorry for the newbie question, but can someone tell me what IFn means exactly? I keep running into it in the docs particularly in the keyword documentation, and Google has yet to expain. Thanks, Travis -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: areduce flaw
no, the syntax is not the same. user= (macroexpand-1 '(.foo bar)) (. bar foo) On Mon, Apr 27, 2009 at 2:51 PM, Boris Mizhen bo...@boriska.com wrote: Hi Meikel, thanks for the answer. I wonder if someone could explain or point me to the explanation about *why* a Java static fn can't be passed just like a closure fn? After all the syntax to call them is the same :) Thanks, Boris On Apr 27, 5:34 pm, Meikel Brandmeyer m...@kotka.de wrote: Hi, Am 27.04.2009 um 23:17 schrieb Boris Mizhen: ((comp #(Math/abs %) +) -3 -4) = 7 How can I pass a static java function to another function? Here you already gave the answer to your question. Wrap it in a Clojure fn/#(). A member function must be trickier because this must be supplied, but perhaps a macro can be created that results in a function that would capture this and call the member function appropriately ... #(.someMethod an-object %) Or passing in the object: #(.someMethod %1 %2) For apply and friends one needs a more elaborate way. Search for rhickey jcall site:paste.lisp.org. Sincerely Meikel smime.p7s 5KViewDownload -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: constructing maps
(into {} (apply map vector
'((cars bmw chevrolet ford peugeot)
(genres adventure horror mystery
{ford mystery, chevrolet horror, bmw adventure, cars genres}
On Mon, May 4, 2009 at 4:03 PM, Michel S. michel.syl...@gmail.com wrote:
On May 4, 5:07 pm, Christophe Grand christo...@cgrand.net wrote:
Michel S. a écrit :
(apply conj {} (map split-kv (split-pairs test-str)))
The last can be simplified by using into:
(into {} (map split-kv (split-pairs test-str)))
It should be noted that into (and conj) is somewhat tricky with maps:
user= (into {} '({1 2} {3 4}))
{3 4, 1 2}
user= (into {} '([1 2] [3 4]))
{3 4, 1 2}
user= (into {} '((1 2) (3 4)))
java.lang.ClassCastException: java.lang.Integer cannot be cast to
java.util.Map$Entry (NO_SOURCE_FILE:0)
It bit me before.
Yes, me too. The design is a bit unfortunate, as I cannot convert a
Scheme-style association list to a map easily:
user= (into {} '((cars bmw chevrolet ford peugeot)
(genres adventure horror mystery)))
java.lang.ClassCastException: clojure.lang.Symbol cannot be cast to
java.util.Map$Entry (NO_SOURCE_FILE:0)
--
Michel
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Re: Can for be enhanced to not have to take a binding?
user= (doc take-while) - clojure.core/take-while ([pred coll]) Returns a lazy sequence of successive items from coll while (pred item) returns true. pred must be free of side-effects. nil user= On Thu, May 7, 2009 at 2:11 PM, CuppoJava patrickli_2...@hotmail.com wrote: I'm trying to accomplish the following: Create a lazy sequence of calls to f() while pred() is true. And an elegant way to do this seems to be: (for [:while (pred)] (f)) which doesn't work because (for) requires a binding. This can be worked around with: (for [i (constantly 0) :while (pred)] (f)) which is not as elegant. Does anyone else think this is a worthwhile to for? Thanks for your opinions. -Patrick -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Help with Type Hint
so I took a look at with this code: http://gist.github.com/111935 output: :original Elapsed time: 369.683 msecs :redux-1 Elapsed time: 11672.329 msecs :redux-2 Elapsed time: 74.233 msecs as to why there is such a huge difference between your code and redux-2 I am not sure. I would definitely take a look at http://clojure.org/java_interop#toc46 if you haven't yet. On Thu, May 14, 2009 at 1:19 PM, Dimiter malkia Stanev mal...@gmail.com wrote: This is the best I was able to come up with in Clojure: (defn byte-array-contains? [coll key] scans a byte array for a given value (let [c (int (count coll)) k (byte key)] (loop [i (int 0)] (if ( i c) (if (= k (aget coll i)) true (recur (unchecked-inc i))) On May 14, 8:22 am, tmountain tinymount...@gmail.com wrote: I'm trying to optimize some code I've written, and I have set warn on reflection as advised. I'm having a hard time getting a simple statement to avoid reflection. user= (== (byte 0x1) (byte 0x1)) Reflection warning, line: 33 - call to equiv can't be resolved. Can you use type hints on primitive types? I've tried obvious stuff like: user= (== #^byte (byte 0x1) #^byte (byte 0x1)) Reflection warning, line: 4 - call to equiv can't be resolved. and other variations without success. Thanks, Travis -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: The thread ring problem
http://gist.github.com/120289 using queues and Threads instead of agents
On Fri, May 29, 2009 at 4:11 PM, Laurent PETIT laurent.pe...@gmail.com wrote:
Hi,
here is a second attempt, partly inspired by clojure's agents page,
that looks better (true direct ring of agents, not just indirect ring
via vector), and that performs similarly to my first attempt.
Still room for progress, though.
(ns shootout.ring2
(:gen-class))
(def n-threads 503)
(def nb-pass 5000)
(defn agent-fn [state token-val stop-val print-result-fn start-time]
(if (= token-val stop-val)
(print-result-fn (:name state) start-time)
(send (:next state) agent-fn (inc token-val) stop-val
print-result-fn start-time))
state)
(defn main
main function calling the benchmark test.
[n-threads N print-result-fn]
(let [agent-n (agent {:name n-threads :next nil})
agent-1 (reduce (fn [a n] (agent {:name n :next a})) agent-n
(range (dec n-threads) 0 -1))]
(send agent-n assoc :next agent-1)
(send agent-1 agent-fn 0 N print-result-fn (System/nanoTime))
nil))
(defn repl-print-result-fn [thread-id start-time]
(println \n
thread number: thread-id \n
time (secs): (/ (- (System/nanoTime) start-time) 10.0)))
(defn benchmark-print-result-fn [thread-id _]
(println thread-id))
(defn -main []
(main n-threads nb-pass benchmark-print-result-fn))
(defn repl-test [nb-pass]
(main n-threads nb-pass repl-print-result-fn))
2009/5/29 Sean Devlin francoisdev...@gmail.com:
Would type hints help at all?
On May 29, 11:40 am, Laurent PETIT laurent.pe...@gmail.com wrote:
Hi,
Here is my attempt, for the real benchmark test, it has an honorable
result of 62 sec. (if there is no flaw in my algorithm, of course).
;; file shootout/ring.clj
(ns shootout.ring
(:gen-class))
(def n-threads 503)
(def nb-pass 5000)
(defn main
main function calling the benchmark test.
[n-threads N print-result-fn]
(let [start-time (System/nanoTime)
agents (into [] (map #(agent {:name (inc %)}) (range n-threads)))
send-to (fn this [i token-val]
(send (nth agents (mod i n-threads))
(fn [state t-val]
(if (= t-val N)
(print-result-fn (:name state) start-time)
(this (inc i) (inc t-val)))
state)
token-val))]
(send-to 0 0)
nil))
(defn repl-print-result-fn [thread-id start-time]
(println \n
thread number: thread-id \n
time (secs): (/ (- (System/nanoTime) start-time)
10.0)))
(defn benchmark-print-result-fn [thread-id _]
(println thread-id))
(defn -main []
(main n-threads nb-pass benchmark-print-result-fn))
(defn repl-test [nb-pass]
(main n-threads nb-pass repl-print-result-fn))
;; repl session
Clojure
1:1 user= (use 'shootout.ring)
nil
1:2 user= (do (repl-test 1000) (repl-test 5000))
nil
1:3 user=
thread number: 498
time (secs): 0.128037133
thread number: 292
time (secs): 62.724999733
on a recent machine
(and yes, I know something similar is on the clojure agents page, but
sometimes it's rewarding not to look at the solution too early :-)
Cheers,
--
Laurent
2009/5/29 Alvaro Vilanova Vidal alv...@gmail.com:
Thanks, seems that I misunderstood Agents :)
The solution of Christian works well with full load, but maybe slow for
the
benchmark. In my core2duo, with full load, takes about 28mins to compute
the
result.
user= (do (println (System/nanoTime)) (start 5000))
22651751153117
#ag...@27a897a9: 1
user= 292 ( 24319344452689 )
user= (/ (- 24319344452689 22651751153117) 600.0)
27.79322165954
2009/5/29 Christian Vest Hansen karmazi...@gmail.com
On Fri, May 29, 2009 at 4:29 PM, Laurent PETIT laurent.pe...@gmail.com
wrote:
when I try it with the 50,000,000 number of times the token is
exchanged (which is the number to be used for the benchmark)
Oh, right. I only noticed the 1000 mentioned at the bottom. Also, the
(time ...) makes no sense.
How would one fix this?
With a CountDownLatch? That's what I'm currently trying.
2009/5/29 Christian Vest Hansen karmazi...@gmail.com:
For kicks, I made an implementation* using agents:
http://gist.github.com/119946
I think that you may not want to use the STM so much and instead
figure out a different approach to sending the token around the ring.
*it may be a bit liberal in its interpretation of the rules... didn't
read them that carefully.
On Fri, May 29, 2009 at 2:32 PM, Alvaro Vilanova Vidal
alv...@gmail.com wrote:
Hi everyone,
I am a newbie in clojure world, so I have some newbie's questions :)
To
learn about clojure, I am trying to do the thread ring problem of
clgb
in
Re: Using (into {} ...) on a sequence of lists vs. vectors
two element vectors implement MapEntry, (into {} x) x needs to be
something that seq can be called on and will return a seq of MapEntrys
On Mon, Jun 1, 2009 at 10:39 AM, samppi rbysam...@gmail.com wrote:
Why does using a list with into and a map throw an exception, while
using a vector is fine?
Clojure 1.0.0-
user= (def a (list :a 1))
#'user/a
user= (into {} [a])
java.lang.ClassCastException: clojure.lang.Keyword cannot be cast to
java.util.Map$Entry (NO_SOURCE_FILE:0)
user= (def b [:a 1])
#'user/b
user= (into {} [b])
{:a 1}
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And what is not good—
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Re: New and stuck ??
the new entry point is clojure.main java -cp clojure.jar clojure.main ;no slash, with the corrent jar name java -cp clojure.jar clojure.main --help will print a nice help message On Sun, Jun 7, 2009 at 8:20 AM, darrelldgalli...@gmail.com wrote: OK, embarrassing Thanks, I was caught wishing to see a wow fun demo, without thought on my part. -= Darrell On Jun 7, 10:13 am, Kyle R. Burton kyle.bur...@gmail.com wrote: I think your ls showed it, the jar name is clojure-1.0.0.jar, so the java -cp argument should point to that instead: java -cp clojure-1.0.0.jar clojure.lang.Repl Kyle -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: The - . nested usage
sure it can, you just need to pass in an initial value. (- (String.) String. String.) ; works (- x String. String.) ;works for any x where string has a constructor that takes something of type x for example (- file.txt File. FileReader. BufferedReader.) will return a buffered reader on file.txt (assuming you import those classes from java.io) On Mon, Jun 8, 2009 at 12:59 PM, ronennark...@gmail.com wrote: I see, using - with . will not create a chain of new invocations, the best solution that iv found is: user= (String. (String.)) user= (macroexpand (String. (String.))) user= (macroexpand `(String. (String.))) (new java.lang.String (java.lang.String.)) Nesting is a must :) Thank you both for your helpful reply On Jun 8, 10:51 pm, Kevin Downey redc...@gmail.com wrote: you need to pass something in. example: = (- foo String. String.) foo = (macroexpand '(- String. String.)) (new String String.) = (macroexpand '(- foo String. String.)) (new String (clojure.core/- foo String.)) = (macroexpand '(- foo String.)) (new String foo) String. is only treated as new String ... when it is placed in the function position (String. ...) in (- String. String.) the first String. is never put in the function position, so effectively you get (String. String.) On Mon, Jun 8, 2009 at 12:38 PM, ronennark...@gmail.com wrote: Following a blog post on building large object graphs I was suggested with the following solution: (def nested-object (- GrandFather. Father. GrandSon.)) this indeed seems to be correct however fails in even in a simple example: user= (- String. String.) java.lang.ClassNotFoundException: String. (NO_SOURCE_FILE:7) expanding the macros involved seems to reveal the issue: user= (macroexpand-1 `(- String. String.)) (java.lang.String. java.lang.String.) the . macro isn't expanded. Is there a way of applying nested macros? (iv searched for applying nested macros with no results). -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Thoughts on bags?
On Tue, Jun 9, 2009 at 7:49 PM, Richard Newmanholyg...@gmail.com wrote:
Thanks, Konrad and Andrew, for chipping in!
There's an outline of an implementation of multisets (I think that's
the same as your bags) at:
http://code.google.com/p/clojure-contrib/source/browse/trunk/src/
clojure/contrib/types/examples.clj
Thanks for the pointer.
I apologize for the negativity, but these don't seem first class --
that is, I can't treat them as I would sets:
user= (map identity #{:a :b :c})
(:a :c :b)
user= (map identity (gc/conj (multiset {}) :a :b :c)))
([:c 1] [:b 1] [:a 1])
all that needs to happen is for multiset to provide it's own seq, like
it supplies it's own conj. seq would strip whatever information out.
you would need to call it explicitly on the multiset before passing it
to functions which call seq internally (map, filter, etc).
The cardinality tracking has been (necessarily, I understand) lifted
into the explicit contents of the data structure, so applications
which call Clojure code that performs core operations (not your
generic versions) on those structures will not work.
Consequently, I couldn't use these with clojure.set's relational
operations, for example:
user= (clojure.set/join
#{{:name John :id 4} {:name John :id 3}}
#{{:age 32 :id 4} {:age 19 :id 3}})
#{{:age 19, :name John, :id 3} {:age 32, :name John, :id 4}}
user= (clojure.set/join
(gc/conj (multiset {}) {:name John :id 4} {:name
John :id 3})
(gc/conj (multiset {}) {:age 32 :id 4} {:age 19 :id 3}))
java.lang.ClassCastException: clojure.lang.PersistentArrayMap cannot
be cast to java.util.Map$Entry (NO_SOURCE_FILE:0)
So far as I understand it, to get 'native' multisets would require an
implementation of IPersistentCollection, or perhaps IPersistentSet
itself (if the contract of the interface doesn't impose set
semantics), and ideally some Clojure surface syntax.
PersistentTreeSet doesn't look too scary, so perhaps I'll dive in...
more fun than my paid work, after all :)
Google Collections has Multisets - and they have an immutable
implementation.
http://code.google.com/p/google-collections/
Hmm, interesting. Not sure how their builder-based approach would fit
in.
For now, as I'm storing maps in my sets -- I'm doing relational stuff,
after all -- I just add an :id entry in each map, filled by (iterate
inc 0). Functionally the same as a multiset, so long as I ignore
the :id 'column'...
--
And what is good, Phaedrus,
And what is not good—
Need we ask anyone to tell us these things?
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Re: EDT interaction
On Sat, Jun 13, 2009 at 2:02 PM, Wrexsould2387...@bsnow.net wrote: Now I'm working on some Swing code and came up with these, which are obviously going to be useful: (defmacro do-on-edt [ body] `(SwingUtilities/invokeLater #(do ~...@body))) (defmacro get-on-edt [ body] `(let [ret# (atom nil)] (SwingUtilities/invokeLater #(reset! ret# [(do ~...@body)])) (loop [] (let [r# @ret#] (if r# (first r#) (recur)) (defmacro future-on-edt [ body] `(future (get-on-edt ~...@body))) The do-on-edt macro executes its body on the EDT and returns nil. The get-on-edt macro does similarly, but returns whatever the body returns. It blocks until the body has returned, though, which you may not want, though since it executes on the EDT it should execute fast. The future-on-edt macro avoids this blocking behavior. It behaves as if you scheduled its body to run as a future on the EDT instead of on whatever thread(s) futures usually run on. In actual fact, the future it returns is executing the blocking get-on-edt. :) Action listener code can assume it will run on the edt, but plenty of other things do not; notably, REPL expressions do not, as well as anything explicitly launched into another thread and anything executed as a result of load-file or via a main class. This code, which I offer to the public domain, also furnishes some simple examples of macro design, as well as of the use of an atom to move information between threads, plus a recurrence of the one-cell- vector idiom for having both nil and meta-nil, distinguishing not- set-yet from actually-returned-nil. This also showed up in super-lazy- seq where ultimately one var could end up holding either a boxed return value or *two* out-of-band values, nil and :skip. (Another trick for returning out-of-band values is to return a two-element vector with a value in one cell and an accompanying bit of meta-data in the other, for example [item found] distinguishing [nil false] from [nil true]. Other lisps admit of the same trick, using a cons cell (item . found) for instance, or using nil vs. (item . nil) or any-atom vs. (item . nil). Don't know if anyone else here is familiar with dotted-pair notation though, except clojure's author.) get-on-edt uses a busy loop, which is icky. I would use a blockingqueue. if you are not constrained by 1.0 compatibility promise/deliver just hit the new git repo. a promise is a new kind of reference type that provides a blocking deref. http://github.com/richhickey/clojure/blob/1a0e23d0e78ef3d3a3a6267a68adcfc414d3fb56/src/clj/clojure/core.clj#L4152 -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: EDT interaction
On Sat, Jun 13, 2009 at 2:55 PM, Meikel Brandmeyerm...@kotka.de wrote: Hi, Am 13.06.2009 um 23:29 schrieb Meikel Brandmeyer: (defmacro get-on-edt [ body] `(get-on-edt* (fn [] ~body))) Of course ~...@body instead of ~body... Sincerely Meikel I know you (Meikel) already fixed it, but I guess it is a good idea to explain that have a macro expand to a #() form is a bad idea. the original do-on-edt macro did expand to a #() form, which means if you passed in another #() form you would end up with nested #() forms, which causes an exception. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: EDT interaction
it depends how often you are pushing stuff onto the EDT. I have a similar macro called EDT so I can do stuff like (EDT (.setText foo bar)) alternatively I would need to type (SwingUtilities/invokeLater #(.setText foo bar)) or even (SwingUtilities/invokeLater (fn [] (.setText foo bar))) On Sat, Jun 13, 2009 at 5:23 PM, Aaron Cohenremled...@gmail.com wrote: Isn't this a case of wrapping a Java API needlessly? What's so bad about: (SwingUtilities/invokeLater my-func) ? -- Aaron On Sat, Jun 13, 2009 at 5:59 PM, Kevin Downeyredc...@gmail.com wrote: On Sat, Jun 13, 2009 at 2:55 PM, Meikel Brandmeyerm...@kotka.de wrote: Hi, Am 13.06.2009 um 23:29 schrieb Meikel Brandmeyer: (defmacro get-on-edt [ body] `(get-on-edt* (fn [] ~body))) Of course ~...@body instead of ~body... Sincerely Meikel I know you (Meikel) already fixed it, but I guess it is a good idea to explain that have a macro expand to a #() form is a bad idea. the original do-on-edt macro did expand to a #() form, which means if you passed in another #() form you would end up with nested #() forms, which causes an exception. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Primitive char Type
user= (def s (StringBuilder. aaa)) #'user/s user= (. s setCharAt 0 \b) nil user= s #StringBuilder baa user= (. s setCharAt (int 0) (char \b)) nil user= (. s setCharAt (int 0) (char \e)) nil user= s #StringBuilder eaa user= works for me On Sat, Jun 13, 2009 at 7:28 PM, tmountaintinymount...@gmail.com wrote: I'm writing some simple code, and I believe I'm running into trouble getting a primitive char. user= (def s (new StringBuilder aaa)) #'user/s ; Java method signature is setCharAt(int index, char ch) user= (. s setCharAt (int 0) (char \a)) java.lang.IllegalArgumentException: No matching method found: setCharAt for class java.lang.StringBuilder (NO_SOURCE_FILE:0) user= (type (char \a)) java.lang.Character ; should be char? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Rebinding functions?
you can use apply to avoid in-lining: user= (binding [+ -] (apply + '(5 3))) 2 On Tue, Jun 16, 2009 at 11:16 AM, Michel S.michel.syl...@gmail.com wrote: On Jun 16, 1:42 pm, Paul Stadig p...@stadig.name wrote: On Tue, Jun 16, 2009 at 1:38 PM, Michel Salim michel.syl...@gmail.comwrote: It's currently not possible to dynamically rebind functions: (binding [+ -] (+ 5 3)) == 8 ;; not 2 Thanks, -- Michel S. It is possible to rebind (even core) functions, but there are a couple of limitations. One of which is the fact that some functions are inlined by the compiler. I believe the two argument case of '+ is one of those. I just verified and it does indeed work -- thanks. Time to read up on macros to implement this tracing construct, then. -- Michel -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
with-open binding form
I noticed with-open kind of stuck out because it doesn't use vectors for binding like let, loop, and others. it was a quick fix using destructuring to make the macro use square backets example: (with-open [f (new java.io.FileWriter test)] do-stuff) but as I was writing an email to this list I realized that let,loop, etc do multiple bindings. so a few hours later I had this: (defmacro better-with-open [b f] (let [q b h (map (fn[x] `(. ~x (close))) (take-nth 2 q))] `(let ~q (try [EMAIL PROTECTED] (finally [EMAIL PROTECTED]) sorry about all the single letter variables, I am not exaggerating about how long this took. Still wrapping my head around macros. usage example: (better-with-open [f (new java.io.FileWriter foo true) q (new java.io.FileWriter bar)] (. f (write one)) (. q (write two))) -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
is clojure known to work on any phones with javame?
I am in the market for a phone and it would be so cool to have clojure on it. Has anyone tried this yet? -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Getting a flat sequence from a map (and vice versa)
On Fri, Nov 14, 2008 at 8:17 PM, samppi [EMAIL PROTECTED] wrote:
Yeah, I need to be able to do this to easily manage trees of maps. I
meant, how would you idiomatically implement their algorithms?
Fold isn't build into Clojure, but they should still somehow be
possible...right?
On Nov 14, 9:12 pm, Michel Salim [EMAIL PROTECTED] wrote:
On Nov 14, 10:56 pm, samppi [EMAIL PROTECTED] wrote: I'm trying to figure
out how to do this:
(flat-map-seq {:a 3, :b 1, :c 2}) ; returns (:a 3 :b 1 :c 2)
(defn flat-map-seq [m]
(if (empty? m) '()
(let [kv (first m)]
(lazy-cons (kv 0) (lazy-cons (kv 1) (flat-map-seq (rest m)))
...and vice versa:
(map-from-flat-collection {} [:a 3 :b 1 :c 2]) ; returns {:a 3, :b
1, :c 2}
(defn map-from-flat-collection [c]
(if (empty? c) {}
(conj (map-from-flat-collection (rrest c)) [(first c) (frest
c)])))
Anyone have any idiomatic ideas?
Well, not sure how idiomatic this is; apart from conj, this is how
you'd do it in Lisp/Scheme. I'd use fold to do the first function if
it's built into Clojure.
Regards,
--
Michel
(apply assoc {} [:a 1 :b 2 :c 3])
- {:c 3, :b 2, :a 1}
--
The Mafia way is that we pursue larger goals under the guise of
personal relationships.
Fisheye
--~--~-~--~~~---~--~~
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Re: Getting a flat sequence from a map (and vice versa)
On Fri, Nov 14, 2008 at 8:33 PM, Kevin Downey [EMAIL PROTECTED] wrote:
On Fri, Nov 14, 2008 at 8:17 PM, samppi [EMAIL PROTECTED] wrote:
Yeah, I need to be able to do this to easily manage trees of maps. I
meant, how would you idiomatically implement their algorithms?
Fold isn't build into Clojure, but they should still somehow be
possible...right?
On Nov 14, 9:12 pm, Michel Salim [EMAIL PROTECTED] wrote:
On Nov 14, 10:56 pm, samppi [EMAIL PROTECTED] wrote: I'm trying to
figure out how to do this:
(flat-map-seq {:a 3, :b 1, :c 2}) ; returns (:a 3 :b 1 :c 2)
(defn flat-map-seq [m]
(if (empty? m) '()
(let [kv (first m)]
(lazy-cons (kv 0) (lazy-cons (kv 1) (flat-map-seq (rest m)))
...and vice versa:
(map-from-flat-collection {} [:a 3 :b 1 :c 2]) ; returns {:a 3, :b
1, :c 2}
(defn map-from-flat-collection [c]
(if (empty? c) {}
(conj (map-from-flat-collection (rrest c)) [(first c) (frest
c)])))
Anyone have any idiomatic ideas?
Well, not sure how idiomatic this is; apart from conj, this is how
you'd do it in Lisp/Scheme. I'd use fold to do the first function if
it's built into Clojure.
Regards,
--
Michel
(apply assoc {} [:a 1 :b 2 :c 3])
- {:c 3, :b 2, :a 1}
--
The Mafia way is that we pursue larger goals under the guise of
personal relationships.
Fisheye
user= (apply concat (seq {:c 3, :b 2, :a 1}))
(:c 3 :b 2 :a 1)
user=
--
The Mafia way is that we pursue larger goals under the guise of
personal relationships.
Fisheye
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Re: Getting a flat sequence from a map (and vice versa)
user= (reduce concat {:a 1 :b 2 :c 3})
(:c 3 :b 2 :a 1)
user=
On Sat, Nov 15, 2008 at 4:02 AM, Matthias Benkard [EMAIL PROTECTED] wrote:
On 15 Nov., 05:17, samppi [EMAIL PROTECTED] wrote:
Fold isn't build into Clojure
Isn't fold just clojure/reduce?
Matthias
--
The Mafia way is that we pursue larger goals under the guise of
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Fisheye
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Re: Getting a flat sequence from a map (and vice versa)
user= (mapcat identity {:a 1 :b 2 :c 3})
(:c 3 :b 2 :a 1)
On Sat, Nov 15, 2008 at 4:05 AM, Kevin Downey [EMAIL PROTECTED] wrote:
user= (reduce concat {:a 1 :b 2 :c 3})
(:c 3 :b 2 :a 1)
user=
On Sat, Nov 15, 2008 at 4:02 AM, Matthias Benkard [EMAIL PROTECTED] wrote:
On 15 Nov., 05:17, samppi [EMAIL PROTECTED] wrote:
Fold isn't build into Clojure
Isn't fold just clojure/reduce?
Matthias
--
The Mafia way is that we pursue larger goals under the guise of
personal relationships.
Fisheye
--
The Mafia way is that we pursue larger goals under the guise of
personal relationships.
Fisheye
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Re: strings
(apply str (reverse I am cold)) shorter and it does the same thing. no need to take out the spaces and put them back in On Tue, Nov 18, 2008 at 5:21 PM, Mark Volkmann [EMAIL PROTECTED] wrote: Here's another solution that came from help on the chat. Thanks Chouser! (apply str (interpose (reverse (.split I am cold On Tue, Nov 18, 2008 at 7:15 PM, islon [EMAIL PROTECTED] wrote: (defn string-reverse [s] (reduce #(str %1 %2) (reverse (seq (. s (split )) You're probably looking for something like this =) On Nov 18, 9:00 pm, joejoe [EMAIL PROTECTED] wrote: hello all, so I'm not only new to this group but I am new to Clojure. I may be going about this all wrong but here's what I got. I want to simply take a string and reverse it, ex: I am cold would become cold am I (haha I just realized that's probably how yoda would say it). So for now I am hard coding my string, so myString =I am cold. How I am thinking of doing this is as follows: (loop [i 0] (when ( i (count myString)) //missing code // // (recur (inc i so this probably isn't a hard thing to do but like I said I am new to this all. I basically need to figure out a way to print each element of myString one at a time, this would allow me to figure out how to reverse it. so to my simple question, is it possible it print each element of a string independently? I know about (first myString), which will give me I printed out three times. So it seems there has to be a way and I just can't seem to figure it out. thanks for any input! -joejoe -- R. Mark Volkmann Object Computing, Inc. -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: seq and vector
I don't think you understand. clojure data structures are IMMUTABLE. every call to conj, or anyother function returns a new object. To optimize there is sharing of structure. On Sun, Nov 23, 2008 at 4:38 AM, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: On Nov 23, 1:23 am, Rich Hickey [EMAIL PROTECTED] wrote: I still don't understand your expectation here. If the filter does any filtering, it won't return everything in the vector, so the new result will have fewer items. Do you want a vector with fewer items? Then you'll have a new vector. Sure. But I get a seq and not a vector. Now don't get me wrong - I like the whole sequence library. It's just the performance cost to get a vector back. That's why I mean relative to seqs the data structures sometimes feel like second class. In my example I no longer use a vector to hold items even though that would be the most appropriate data structure. To be more specififc: I have agents whose state is a vector (used as a buffer) of messages. There are a couple of transformation functions, e.g. tagging messages, removing messages from the vector etc. which are implemented with map and filter. In addition when messages are appended to the vector, conj is used and messages end up at the end of the vector. Later I noticed that the order was screwed because some intermediate tagging (using map) returned a secuence as the new agent's state and later additions with conj prepended messages at the front. This motivated me to ask for the simplest and most efficient way to get a vector back because that's what I wanted. Now I use a list instead of a vector and use reverse when necessary. In general, it can be efficient to perform a series of transformations in the seq space and then realize a vector at the end if you want. The lazy seqs just act as a cursor over the data, and a stream of results, and building a new vector from scratch by appending, as vec or (into [] ...) would do, is more efficient than element 'replacement'. If you don't expect a copy when mapping across an entire vector, and you want to use the immutable data structures, what alternative do you imagine? I certainly don't want to move away from immutability. It's more an issue with the return types. In the example setting outlined above suppose I have a message buffer (vector) of length n. Now some messages need to be tagged, which means mapping over the vector and possibly changing some messages. Now by changing I mean of course that the message m which is a map is transformed into m' where m' has some :tag key for instance. This mapping over the vector gives me a seq, i.e. the type has changed from vector to a sequence and this type change will cause later appending to the buffer to bahve differently. Now, to get a vector back I was told to use vec which AFAICS is very costly. Your proposal to use reduce in order to build up the new vector was a very good suggestion. For mapping at least. But the general issue for me was the type change. What would I propose? Not sure. I guess this behavior is by design and if I would want to get vectors there ios no way around copying. Which lead me to my conclusion that I better use a list instead of a vector. However it didn't give me that warm and fuzzy feeling that I normally get when programming in Clojure. Sorry that I can't be more specific than this. -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
I know you are asking about refs, but you might want to think about using reduce to walk the line-seq. the nature of reduce lets you have access to the line-seq, two lines at a time no need for a ref. On Mon, Nov 24, 2008 at 2:17 PM, Brian Doyle [EMAIL PROTECTED] wrote: I am parsing a file and to compare the current line with the previous line of the file. I am using line-seq to go thru the file and I thought I would create a ref to store the previous line. When I want to update the previous line value I can't seem to do it. I've never used refs before so I'm sure I'm doing something very stupid. (defstruct line :lat :lon :name) (defn convert [file] (let [prev-line (ref (struct line))] (with-open [r (reader file)] (doseq [l (line-seq r)] (let [ps (split #, l) c-line (struct line (ps 0) (ps 1) (ps 2))] (if (not= c-line @pre-line) (do ; do stuff here then update pre-line (dosync ref-set pre-line (apply struct line (vals c-line))) (println @pre-line ; this prints out all nils doesn't seem to work Sorry if this email is not formatted correctly. Something is wrong with my browser currently typing in a textarea. Thanks. -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
ref-set needs its one set of parens, and the last thing in the ref-set call needs to be a function either (fn [x] ...) or a symbol for a var that holds a function On Mon, Nov 24, 2008 at 2:30 PM, Brian Doyle [EMAIL PROTECTED] wrote: Thanks Kevin, I will try using reduce instead. I would like to know what I'm doing wrong with updating the ref for future reference. Thanks. On Mon, Nov 24, 2008 at 3:23 PM, Kevin Downey [EMAIL PROTECTED] wrote: I know you are asking about refs, but you might want to think about using reduce to walk the line-seq. the nature of reduce lets you have access to the line-seq, two lines at a time no need for a ref. On Mon, Nov 24, 2008 at 2:17 PM, Brian Doyle [EMAIL PROTECTED] wrote: I am parsing a file and to compare the current line with the previous line of the file. I am using line-seq to go thru the file and I thought I would create a ref to store the previous line. When I want to update the previous line value I can't seem to do it. I've never used refs before so I'm sure I'm doing something very stupid. (defstruct line :lat :lon :name) (defn convert [file] (let [prev-line (ref (struct line))] (with-open [r (reader file)] (doseq [l (line-seq r)] (let [ps (split #, l) c-line (struct line (ps 0) (ps 1) (ps 2))] (if (not= c-line @pre-line) (do ; do stuff here then update pre-line (dosync ref-set pre-line (apply struct line (vals c-line))) (println @pre-line ; this prints out all nils doesn't seem to work Sorry if this email is not formatted correctly. Something is wrong with my browser currently typing in a textarea. Thanks. -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
On Mon, Nov 24, 2008 at 2:34 PM, Kevin Downey [EMAIL PROTECTED] wrote: ref-set needs its one set of parens, and the last thing in the ref-set call needs to be a function either (fn [x] ...) or a symbol for a var that holds a function I made a mistake here. I was thinking of alter, not ref-set. On Mon, Nov 24, 2008 at 2:30 PM, Brian Doyle [EMAIL PROTECTED] wrote: Thanks Kevin, I will try using reduce instead. I would like to know what I'm doing wrong with updating the ref for future reference. Thanks. On Mon, Nov 24, 2008 at 3:23 PM, Kevin Downey [EMAIL PROTECTED] wrote: I know you are asking about refs, but you might want to think about using reduce to walk the line-seq. the nature of reduce lets you have access to the line-seq, two lines at a time no need for a ref. On Mon, Nov 24, 2008 at 2:17 PM, Brian Doyle [EMAIL PROTECTED] wrote: I am parsing a file and to compare the current line with the previous line of the file. I am using line-seq to go thru the file and I thought I would create a ref to store the previous line. When I want to update the previous line value I can't seem to do it. I've never used refs before so I'm sure I'm doing something very stupid. (defstruct line :lat :lon :name) (defn convert [file] (let [prev-line (ref (struct line))] (with-open [r (reader file)] (doseq [l (line-seq r)] (let [ps (split #, l) c-line (struct line (ps 0) (ps 1) (ps 2))] (if (not= c-line @pre-line) (do ; do stuff here then update pre-line (dosync ref-set pre-line (apply struct line (vals c-line))) (println @pre-line ; this prints out all nils doesn't seem to work Sorry if this email is not formatted correctly. Something is wrong with my browser currently typing in a textarea. Thanks. -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: loop recur vs recursion
the jvm does not do TCO, loop/recur allows for functional looking
recursion on the jvm with constant stack size.
On Sat, Nov 29, 2008 at 1:25 AM, bOR_ [EMAIL PROTECTED] wrote:
Hi all,
I wondered if there is a difference between using loop-recur or merely
writing a recursive function. The main difference I found thus far was
that the loop-recur can suffice with less arguments, but the recursive
functions seem to be shorter, and perhaps more elegant?
(defn construct-atom
translates a number n into an set of letters of size n
[construct length]
(if ( (count construct) length)
(construct-atom (conj construct (char (+ (rand-int amino_acids)
65))) length)
construct))
(defn construct-atom-loop
translates a number n into an set of letters of size n
[n]
(let [base_construct #{}]
(loop [construct base_construct]
(if ( (count construct) n)
(recur (conj construct (char (+ (rand-int amino_acids) 65
construct
--
And what is good, Phaedrus,
And what is not good—
Need we ask anyone to tell us these things?
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Re: Possible minor bug in gen-class: method name character escaping?
On Fri, Jan 16, 2009 at 12:22 PM, Greg Harman ghar...@gmail.com wrote: 2. If I want the Clojure functions that underlie the methods in the generated class used directly by my Clojure code as well (which I do), then I'm stuck having to either violate standard Clojure/Lisp function naming conventions in favor of Java-friendly naming or I have to write wrapper functions like: (defn myMethod [obj] (my-method obj)) Other than using the prefix and keeping the method names to one word, is there a better way? Since gen-class is used to create Java classes, it's sensible that the naming convention within the generated class be Java's. I agree that the convention inside the generated class should be a Java convention (my original post was more of an experiment than an attempt to create a working class with that signature). However, I find myself wanting to write a clojure function that can be exposed to both Clojure and Java code, and I'd like to keep them in their respective paradigms. That is, in Clojure, I don't want to have to call (.myMethod foo) when I already have (my-method) defined. And in Java, I want to just use foo.myMethod(), not have to wrap up a call to RT.var().invoke(). I know I'm being picky, but it just seems cleaner this way... write a macro that takes all fns in the current namespace and generates wrappers with the correct naming style. problem solved. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Printing Strings in Lists
prn On Fri, Jan 23, 2009 at 11:00 AM, Kevin Albrecht onlya...@gmail.com wrote: Below are two operations that print (1 2 3 4). How can I do something similar to print (1 2 3 4) to standard out? (println '(1 2 3 4)) - (1 2 3 4) (def x 1 2 3) (println `(~x 4)) - (1 2 3 4) --Kevin Albrecht -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Binding values in a list of symbols and evaluating as code
instead of using binding and eval, you can generate a (fn ) form, eval it, keep the result function stuffed away somewhere and apply it instead of calling eval all the time On Fri, Jan 23, 2009 at 1:10 PM, Zak Wilson zak.wil...@gmail.com wrote: It does seem like a legitimate use for eval, at least at first glance. The biggest problem is that using eval this way is really slow when each rule is being tested on hundreds of inputs. Interesting alternative, Konrad. I can probably take advantage of the fact that all of the functions I'm calling (unchecked math and bitwise operators) take exactly two arguments. I might give something like that a try. I'd rather not though, if I can avoid it. It seems like there ought to be a way to make a function out of a list of symbols that would be a valid function body and then call it repeatedly. I was playing around with that approach at first, but never managed to get it right. I strongly suspect creating a function once and calling it 400 times will be faster than calling eval 400 times. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Length of Sequence
(doc count) - clojure.core/count ([coll]) Returns the number of items in the collection. (count nil) returns 0. Also works on strings, arrays, and Java Collections and Maps nil On Wed, Jan 28, 2009 at 11:15 AM, Peter Wolf opus...@gmail.com wrote: Here's a dumb question, but I can't find it in the docs: How do I get the length of a sequence? Is there some generic way to find the number of elements in something that might be list, map, vector or lazy? There must be some sort of built in function, or an idiom Thanks P -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Alternatives to contains?
actually rhickey showed up on irc and pointed something out:
15:23 rhickey : user= (.contains [1 2 3] 2)
15:23 rhickey : true
15:23 rhickey : user= (.contains '(1 2 3) 2)
15:23 rhickey : true
15:23 rhickey : what contains debate? :)
so because seqs, vectors, etc are java collections
user= (.contains (map #(.getName %) (.getMethods (class (seq [:a]
contains)
true
http://java.sun.com/j2se/1.4.2/docs/api/java/util/Collection.html
On Thu, Jan 29, 2009 at 3:38 PM, Jason Wolfe jawo...@berkeley.edu wrote:
In that case, it makes me think of the degenerate example (I realize
this is slightly stupid):
(some #{false} (list false))
Maybe this is an argument for adding any? to the list of core
functions?
-Jason
--
And what is good, Phaedrus,
And what is not good—
Need we ask anyone to tell us these things?
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Re: Distributed Clojure
have you looked at the available java frameworks like hadoop? there is also some kind of java interface to erlang instead of reinventing the wheel again... On Thu, Jan 29, 2009 at 6:15 AM, Greg Harman ghar...@gmail.com wrote: One of Clojure's big selling points (obviously) is the support for concurrent programming. However, the performance gains you get with this concurrency hits a scalability wall once you're fully utilizing all the cores available in your server. The next step, of course, is to add additional servers. So, I've been mulling over the idea of putting together a framework for distributed applications. I think it should deal with issues such as: * Locating, assessing, and registering CPUs * Division of large jobs into smaller sub-jobs * Dispatching of jobs, including optimization planning (send more jobs to faster CPUs) * Failure recovery * Seamless code integration (so that this can be retrofit as an optimization) both horizontally and vertically * Horizontal = take one time-consuming task and parallelize it * Vertical = take two sequential tasks and pipeline them across different servers Is anybody already working on something similar? Is this already on the Clojure language roadmap as something to be added after 1.0? Any design advice or feature requests if I were to put something like this together? -Greg -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: purpose of clojure-slim.jar
clojure-slim.jar lacks compiled clojure code. The java code is compiled, so clojure-slim.jar is still completely usable as clojure, it just have to compile things like core.clj when it loads them. On Thu, Jan 29, 2009 at 4:56 PM, kkw kevin.k@gmail.com wrote: Hi folks, I noticed that when I run 'ant' to build Clojure, in addition to clojure.jar, 'ant' gives birth to clojure-slim.jar. The build.xml says the clojure-slim.jar lacks compiled Clojure code. I don't know what purpose clojure-slim.jar serves. I searched the http://groups.google.com/group/clojure/ and found zero hits. Where would clojure-slim.jar be useful? Kev -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: What is defn-
as a namespace is to a java package, defn- is to private, and defn is to public On Tue, Feb 3, 2009 at 8:19 PM, Terrence Brannon metap...@gmail.com wrote: What is the significance of the dash after defn? How does it differ from defn? Source: http://www.codepoetics.com/wiki/index.php?title=Topics:SICP_in_other_languages:Clojure:Chapter_1#.3B_1.1.4_The_Elements_of_Programming_-_Compound_Procedures -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Tools for parsing arguments
you can also use map destructuring.
(defn x [{:keys [a b c]}]
[a b c])
user= (x {:a 1 :b 2 :c 3})
[1 2 3]
On Fri, Feb 6, 2009 at 7:52 AM, Jeffrey Straszheim
straszheimjeff...@gmail.com wrote:
That is remarkably simple and elegant.
On Fri, Feb 6, 2009 at 10:20 AM, Stuart Sierra the.stuart.sie...@gmail.com
wrote:
On Feb 6, 10:06 am, David Nolen dnolen.li...@gmail.com wrote:
Is there anything in core or contrib for parsing arguments to a
function? Since Clojure fns don't support optional args or even keyword
args, is there a standard set of helpers functions to do this? I looked
around but I didn't see anything obvious.
No, but there is a pattern for keyword args:
(defn my-function [ args]
(let [options (apply hash-map args)]
...))
Then you can call (my-function :keyword value :keyword2 value).
-Stuart Sierra
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Re: core.logic merge substitutions map?
https://github.com/sonian/Greenmail/blob/master/src/clj/greenmail/db.clj#L98-L126 has an example, using clojure.core.logic/all to make a goal which is a conjunction of the clojure.core.logic/== goals On 11/16/13, 5:04 PM, Mark wrote: d'oh! Answering my own question: Just compose the unify functions a la (unify (unify a v1 (:v1 r) v2 (:v2 r)) I have a feeling there is a library function/macro that would make this less messy but I can't find it from the cheatsheet. On Saturday, November 16, 2013 10:31:50 AM UTC-8, Mark wrote: I stumbled across Timothy Baldridge's excellent video http://www.youtube.com/watch?v=HHZ8iqswiCwexplaining how to incorporate data sources into core.logic. It reinvigorated my interest in using core.logic to query SQL RDBMS. I'm stumbling on a pretty simple thing, I think. I've got a table that has three columns, a single primary key column and two value columns. Using the pattern Tim outlines in his video, I've got a relation function that takes three parameters, one for each column and I'm trying to work through the case where the primary key is ground and the value columns are lvars. This translates to a query of the form SELECT v1, v2 FROM t WHERE pkey=?. Of course, this returns two values that must be unified. That's where I'm stuck. I know I want to return a substitution map, but I have two lvars to unify. How do I merge the two substitution maps? Sample code: (defn pkey-v1-v2-o [pkey v1 v2] (fn [a] (let [pkey (walk a pkey) v1 (walk a v1) v2(walk a v2)] (condp = [(not (lvar? pkey)) (not (lvar? v1)) (not (lvar? v2))] [true false false ] (to-stream (let [r (first (query [SELECT v1, v2 FROM T WHERE pkey=? pkey]))] (some-merge-fn (unify a v1 (:v1 r)) (unify a v2 (:v2 r) -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? signature.asc Description: OpenPGP digital signature
Re: odd failure on recursive use of protocol member
extend mutates some state (the protocol definition), so what is happen
here is comp is returning a new function built from the value of the
rest-serialize var (the protocol function before the extend changes it)
and the value of the deref var.
I have not verified this, but I suspect if you use (fn [x]
(rest-serialize (deref x))) instead of the comp version, you will get
the behaviour you expected
On 12/10/13, 11:50 AM, Michael Blume wrote:
I have a protocol RestSerializable to represent data that can be serialized
to json from a REST interface.
(defprotocol RestSerializable
(rest-serialize [this]
Convert to something Cheshire can JSONify))
By default, things are left alone
(extend Object
RestSerializable
{:rest-serialize identity})
But I want atoms and the like to be transparent when serialized
(extend clojure.lang.IDeref
RestSerializable
{:rest-serialize (comp rest-serialize deref)})
I would expect this to mean that, say,
(- 42 atom atom atom atom rest-serialize)
would just unwrap to 42, but in fact it only unwraps the outer atom and
leaves the inner ones alone.
Here's where it gets weird though. If I just evaluate the extend
clojure.lang.IDeref form again, rest-serialize suddenly gains the ability
to unwrap *two* layers of atoms. Eval it again and it can unwrap *three*.
Kinda feels like the exercises in Little Schemer when they're building up
to the Y Combinator.
Here's my REPL session demonstrating this (not shown, but I've verified
this behavior is the same in Clojure 1.5.1 and Clojure 1.6.0-alpha3)
$ lein repl
nREPL server started on port 46049 on host 127.0.0.1
REPL-y 0.2.1
Clojure 1.5.1
Docs: (doc function-name-here)
(find-doc part-of-name-here)
Source: (source function-name-here)
Javadoc: (javadoc java-object-or-class-here)
Exit: Control+D or (exit) or (quit)
Results: Stored in vars *1, *2, *3, an exception in *e
user= (defprotocol RestSerializable
#_= (rest-serialize [this]
#_=Convert to something Cheshire can JSONify))
RestSerializable
user=
user= (extend Object
#_= RestSerializable
#_= {:rest-serialize identity})
nil
user=
user= (extend clojure.lang.IDeref
#_= RestSerializable
#_= {:rest-serialize (comp rest-serialize deref)})
nil
user= (- 7 atom atom atom rest-serialize)
#Atom@56153406: #Atom@a0aa211: 7
user= (- 7 atom atom atom rest-serialize)
#Atom@3c19a5b0: #Atom@37cce4a3: 7
user= (- 7 atom atom atom rest-serialize)
#Atom@9f6e629: #Atom@308092db: 7
user= (extend clojure.lang.IDeref
#_= RestSerializable
#_= {:rest-serialize (comp rest-serialize deref)})
nil
user= (- 7 atom atom atom rest-serialize)
#Atom@7fb48906: 7
user= (- 7 atom atom atom rest-serialize)
#Atom@41e224a5: 7
user= (extend clojure.lang.IDeref
#_= RestSerializable
#_= {:rest-serialize (comp rest-serialize deref)})
nil
user= (- 7 atom atom atom rest-serialize)
7
user= (quit)
Bye for now!
--
And what is good, Phaedrus,
And what is not good—
Need we ask anyone to tell us these things?
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Re: let bindings
On 1/20/14, 12:38 PM, Andy Smith wrote: Hi, (let bindings form) is a special form. As I understand it, let can be reformulated in terms of functions e.g. (let [x 2] (* x 20)) equivalent to ((fn [x] (* x 20)) 2) (let [x 3 y (* x x)] (- y x)) equivalent to ((fn [x] ((fn [x y] (- y x)) x (* x x))) 3) So if we can always reformulate in this was, why cant let be implemented as a macro rather than a special form? Where have I gone wrong in my understanding here? Andy Clojure has made several choices which make implementing let via macro expanding to function application a nonstarter: 1. Clojure is compiled. There is no interpreter for clojure, all clojure code is compiled to bytecode before executing, even at the repl. So the compiler needs to be fast for interactive work and cannot spend a lot of time in optimizing passes typically used to avoid function call overhead for every local name binding. 2. Debuggers There are a number of nice debugging tool kits for Java/the JVM. They operating by reading metadata (like local names) from class files. Because clojure maps let bound locals to the same JVM construct as Java, you can re-use Java debuggers for Clojure. 3. JVM interop The JVM does not have TCO built in, so in order to provide general constant space tail calls you must do extensive code transforms(breaks 1 and 2) or use your own calling convention(method call and trampoline, instead of just a method call) which would complicate interop. Clojure instead provides less general construct loop/recur for constant space iteration. loop/recur is local to a function body, so if let macro expanded to a fn call, you would not be able to recur from inside a let. So while technically possible (there are scheme impls on the jvm that may) Clojure does not expand let in to a fn call -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: test.check, quickcheck concurrency
On 3/28/14, 9:48 PM, Brian Craft wrote: Re: John Hughes' talk at clojure/west, at the end he did a fairly incredible demo of testing concurrency. It doesn't look like this was implemented in test.check (or I'm not finding it). Are there any plans? from my understanding his approach is using quickcheck to generate histories and then check those histories for linearizability. maybe some combination of test.check and https://github.com/aphyr/knossos could do that. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: Adding type hint causes compiler error
On Sun, Jul 5, 2009 at 5:18 AM, philip.hazel...@gmail.comphilip.hazel...@gmail.com wrote: Hi, The following code works as expected: (import 'javax.imageio.ImageIO 'java.io.File 'java.awt.image.BufferedImage) (defn bi-get-pixels [bi] (vec (.. bi (getData) (getPixels 0 0 (.getWidth bi) (.getHeight bi) nil (bi-get-pixels (. ImageIO read (File. /home/phil/prog/small- test.png))) But if *warn-on-reflection* is true, it generates four warnings. If we try to shut it up with a type hint: (defn bi-get-pixels [#^BufferedImage bi] (vec (.. bi (getData) (getPixels 0 0 (.getWidth bi) (.getHeight bi) nil Exception in thread main java.lang.IllegalArgumentException: More than one matching method found: getPixels (imagio-test.clj:7) at clojure.lang.Compiler.analyzeSeq(Compiler.java:4558) ... Caused by: java.lang.IllegalArgumentException: More than one matching method found: getPixels at clojure.lang.Compiler.getMatchingParams(Compiler.java:2122) at clojure.lang.Compiler$InstanceMethodExpr.init (Compiler.java:1159) at clojure.lang.Compiler$HostExpr$Parser.parse(Compiler.java: 810) at clojure.lang.Compiler.analyzeSeq(Compiler.java:4551) ... 34 more The problem here is that getPixels has three forms: ( http://java.sun.com/j2se/1.4.2/docs/api/java/awt/image/Raster.html ) double[] getPixels(int x, int y, int w, int h, double[] dArray) Returns a double array containing all samples for a rectangle of pixels, one sample per array element. float[] getPixels(int x, int y, int w, int h, float[] fArray) Returns a float array containing all samples for a rectangle of pixels, one sample per array element. int[] getPixels(int x, int y, int w, int h, int[] iArray) Returns an int array containing all samples for a rectangle of pixels, one sample per array element. In each case, if the final argument is NULL it is ignored, and if not the array is populated with the return data from the call (generating an error if it's not large enough). Is it possible to specify which invocation of getPixels I intend without passing an array? I've tried putting #^ints in some likely- looking places, but nil can't be type-hinted and the others seem to have no effect. I've also tried splitting the .. up: (defn bi-get-pixels [#^BufferedImage bi] (let [rast (.getData bi) #^ints pi (.getPixels rast 0 0 (.getWidth bi) (.getHeight bi) nil)] pi)) you change (.getPixels rast 0 0 (.getWidth bi) (.getHeight bi) nil) to something like (.getPixels rast (int 0) (int 0) (.getWidth bi) (.getHeight bi) nil) But this doesn't work either. I could do manual reflection on Raster to get the correct method and .invoke it, but that seems far more complicated than necessary. Any other ideas? -Phil -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: ArithmeticException with doubles
On Fri, Jul 10, 2009 at 1:00 PM, Daniel Lyonsfus...@storytotell.org wrote:
On Jul 10, 2009, at 12:24 PM, Sean Devlin wrote:
A quick java program:
public static void main(String[] args) {
System.out.println(1.0/0.0);
}
Infinity
On Jul 10, 11:08 am, John Harrop jharrop...@gmail.com wrote:
This is odd:
user= (/ 1.0 0.0)
#CompilerException java.lang.ArithmeticException: Divide by zero
(NO_SOURCE_FILE:0)
Shouldn't it be Double/POSITIVE_INFINITY?
I think there's still room for an argument here, if anyone wants to
have one.
http://scienceblogs.com/goodmath/2008/10/infinity_is_not_a_number.php
I'm not convinced that x/0 is arithmetically infinity thanks to Mark's
blog post there and it sure bugs me when I do something stupid and get
Infinity back instead of an error. It's like a timebomb in my code,
concealing where the real mistake was. I do like having the constant
there for doing algorithms that depend on it (Dijkstra's SSSP comes to
mind) but I think x/0 is an error (unless it's 0/0).
—
Daniel Lyons
using math knowledge to answer (corner) cases of the floating point
spec is silly
people using doubles should be able to expect doubles to behave like doubles
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And what is not good—
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Re: Clojure vectors
the sequence functions operate on sequences. if you pass in something that is not a sequence, like a vector, they call seq on it internally. so what you get back from filter or map is a sequence. conj has consistent behavior across types, you just get a different type out of map/filter/etc then what goes in. On Mon, Jul 13, 2009 at 8:15 AM, Jan Rychterj...@rychter.com wrote: I've been trying to implement stacks using vectors in Clojure. In case you wonder why, it's because I need stacks with a fast item count operation. While experimenting I discovered some vector properties which were unexpected. conj adds at the end of the vector as expected: user (conj [1 2 3] 4) [1 2 3 4] However, after reading Programming Clojure (page 114) I expected to be able to use sequence functions, such as drop-last, without my vectors changing representation. It seems this is not the case, as after calling drop-last (or indeed any of the seq functions) conj no longer adds at the end: user (conj (drop-last 1 [1 2 3]) 4) (4 1 2) I don't know if it also has performance implications (does it turn my vector into a list?). So it turns out that pretty much the only operations I can use on my vectors are subvec and pop: user (conj (subvec [1 2 3] 0 2) 4) [1 2 4] user (conj (pop [1 2 3]) 4) [1 2 4] user I didn't expect this to happen. Most tutorials (and Stuart Halloway's book) emphasize the generality of the sequence functions, only mentioning that subvec is faster for vectors. I think the fact that they also change subsequent behavior of conj is fundamental and should be printed in bold type. Am I missing something here? And while we're on the subject -- any hints for implementing a stack with a fast item count? (apart from a list with a separate counter) --J. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: another binding issue?
closures capture lexical scope, binding creates dynamic scope. lexical scope is where a closure is defined, dynamic is when it is called. because filter is lazy, the closure is called outside the dynamic scope created by binding On Jul 14, 1:07 pm, Aaron Cohen remled...@gmail.com wrote: I'm a little unclear on why this happens still. #(= % a) is a closure, correct? My understanding is that this should capture the environment when it is defined. Why does the environment not include the current bindings? -- Aaron On Tue, Jul 14, 2009 at 4:03 PM, Mark Engelberg mark.engelb...@gmail.comwrote: On Tue, Jul 14, 2009 at 12:40 PM, Jarkko Oranenchous...@gmail.com wrote: This is a common gotcha. It's actually a laziness issue: the seq produced by filter is realised only after it exits the binding scope, thus producing '(1). You need to use doall to force the seq if you want the binding to apply. Yeah, but more and more I'm finding that with complex code, it can be rather difficult to identify the parts that are lazy and the parts that aren't. Which makes using binding rather risky. I've started to refactor most of my code to avoid dynamic binding, because I'm tired of getting burned by this gotcha. Which is a shame. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: another binding issue?
this is how you do it: user= (def a 0) #'user/a user= (binding [a 1] (map #(+ % a) (range 5))) (0 1 2 3 4) user= (binding [a 1] (let [a a] (map #(+ a %) (range 5 (1 2 3 4 5) user= you capture the dynamic scope in the lexical scope so the closure can close over it. dunno how applicable this is to more complex uses of binding On Tue, Jul 14, 2009 at 6:09 PM, Mark Engelbergmark.engelb...@gmail.com wrote: It almost seems like what you want is for lazy data structures to close over the dynamic vars that have been modified from their root bindings at the time the lazy data structure is created. Seems like coming up with well-defined semantics for this would be an interesting research problem, and if done properly, could end up matching people's intuition and being a lot more useful than the current awkwardness of the way that vars and laziness interact. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Function overriding? Way to do it, similar to in Java
yes there is a way: http://clojure.org/multimethods On Fri, Jul 24, 2009 at 11:44 AM, BerlinBrownberlin.br...@gmail.com wrote: Are there ways to override functions so that if you have different parameters, you get different logic? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: clojure success story ... hopefully :-)
user= (defmulti length empty?) #'user/length user= (defmethod length true [x] 0) #MultiFn clojure.lang.mult...@1807ca8 user= (defmethod length false [x] (+ 1 (length (rest x #MultiFn clojure.lang.mult...@1807ca8 user= (length [1 2 3 4]) 4 On Fri, Aug 21, 2009 at 12:41 PM, Michel Salimmichael.silva...@gmail.com wrote: On Fri, 2009-08-21 at 11:02 -0700, Sigrid wrote: Hi, I read the related story on InfoQ and found it an extremely interesting and motivating read, Clojure being applied in such an interesting field as machine learning! There is something in the article I'd like to understand better, so i'm just asking here on the group: The way that Rich elected to de-couple destructuring bind from pattern matching was brilliant. Could someone point me to what the difference is? I know pattern matching e.g. from the PLT scheme implementation, and there the pattern matching also provides the binding and destructuring I think...? Clojure allows destructuring of vectors, which happens to be what its functions' argument lists are, so you get most of the benefits of pattern matching. It's not full-blown, though, so (correct me if I'm wrong) the equivalent of this is not possible: length [] = 0 length (_:xs) = 1 + (length xs) Regards, -- Michel -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: clojure classpaths
you could try running this test script: http://gist.github.com/179346 the script downloads clojure and does a test aot compile. if everything works the only output you should see is Hello World example: hiredman rincewind ~% sh ./clojure-aot-test.sh Hello World On Tue, Sep 1, 2009 at 11:37 AM, Terrance Davisterrance.da...@gmail.com wrote: The details help a lot. I was able to ensure I am doing the same steps with a file not found exception instead of a working file. I notice that the you used 'clojure.jar' whereas I am using 'clojure-1.0.0.jar'. Did you happen to compile your clojure.jar from source? I used the current release download. I am starting to wonder if I need to build from source to get this classpath problem to go away. On Tue, Sep 1, 2009 at 12:05 PM, Krukowkarl.kru...@gmail.com wrote: On Sep 1, 5:03 pm, Terrance Davis terrance.da...@gmail.com wrote: Okay. Here's some additional information. I have tried on OS X 10.6 and Vista and no dice either place. I am NOT This works for me on Mac: krukow:~/examples$ ls -R classes clojure.jar src ./classes: ./src: clojure ./src/clojure: examples ./src/clojure/examples: hello.clj krukow:~/examples$ java -cp clojure.jar:./src:./classes clojure.main Unable to find a $JAVA_HOME at /usr, continuing with system-provided Java... Unable to find a $JAVA_HOME at /usr, continuing with system-provided Java... Clojure 1.1.0-alpha-SNAPSHOT user= (compile 'clojure.examples.hello) clojure.examples.hello user= (clojure.examples.hello.) #hello clojure.examples.he...@dfbabd user= ^D krukow:~/examples$ java -cp clojure.jar:./src:./classes clojure.examples.hello Karl Unable to find a $JAVA_HOME at /usr, continuing with system-provided Java... Unable to find a $JAVA_HOME at /usr, continuing with system-provided Java... Hello Karl! krukow:~/examples$ -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Dynamically Changing Functions in Compiled Code
gen-class generates a stub java class that dispatches to clojure functions, you can re-def the clojure functions that back the stubbed out class. On Sat, Sep 5, 2009 at 12:10 PM, Gorsals...@tewebs.com wrote: I am trying to add clojure code to an eclipse plugin. To do so, the code i compiled into class files via the clojure-dev plugin. I have a generate class, ParenMatcher, which i use ever so often. This class has a function which i would like to change dynamically while debugging it. In other words, If an error is thrown inside it, i would like to change it instead of closing the plugin and restarting all over again! I've tried recompiling while the plugin is running, but that doesn't work. Any ideas how to do this code hot swapping? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Dynamically Changing Functions in Compiled Code
http://gist.github.com/163140 for example this code creates a repl on port 4445 you can interact with via telnet. so you would have the plugin evaluate this code (to start the repl) you can then telnet in, and past new definitions for the functions On Sat, Sep 5, 2009 at 8:23 PM, Seth Burleighs...@tewebs.com wrote: How is this supposed to work? I use AOT compilation to produce the class files, and I have tried to recompile the functions but it doesn't appear to have an effect. I'm including the clojure as class files, are you saying that all I have to do is recompile the clojure functions? Of course, I have to admit, when I compile something I only know how to compile the whole namespace not just the functions. I guess what I'm saying is that I have no idea how to use the REPL with a running eclipse plugin which has clojure code in it. So I can't simply redef it... -Original Message- From: clojure@googlegroups.com [mailto:cloj...@googlegroups.com] On Behalf Of Kevin Downey Sent: Saturday, September 05, 2009 7:46 PM To: clojure@googlegroups.com Subject: Re: Dynamically Changing Functions in Compiled Code gen-class generates a stub java class that dispatches to clojure functions, you can re-def the clojure functions that back the stubbed out class. On Sat, Sep 5, 2009 at 12:10 PM, Gorsals...@tewebs.com wrote: I am trying to add clojure code to an eclipse plugin. To do so, the code i compiled into class files via the clojure-dev plugin. I have a generate class, ParenMatcher, which i use ever so often. This class has a function which i would like to change dynamically while debugging it. In other words, If an error is thrown inside it, i would like to change it instead of closing the plugin and restarting all over again! I've tried recompiling while the plugin is running, but that doesn't work. Any ideas how to do this code hot swapping? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Correct idiom for looping inside a catch or finally form?
user= (macroexpand '(with-open [x A y Y] do stuff here)) (let* [x A] (try (clojure.core/with-open [y Y] do stuff here) (finally (. x clojure.core/close user= with-open expands to a (try (finally (.close ...))) On Sun, Sep 13, 2009 at 7:38 PM, Richard Newman holyg...@gmail.com wrote: Clojure does not seem to support iteration inside catch or finally forms. Apparently not directly. Splitting the iteration into a separate named function works, though: (defn print-seq [foo] (doseq [x foo] (println x))) (let [foo (atom [1 2 3])] (try (throw (new Exception foo)) (catch Exception e (print-seq @foo so you could try (defn close-all-files [files] (doseq [file files] (.close file))) (let [files (atom [])] (try (open-my-many-files files) ;; the files atom now refers to a vector of open file handles (do-dangerous-io @files) (finally (close-all-files @files -R -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Procedure for getting patches applied
have you seen http://clojure.org/patches ? On Wed, Sep 16, 2009 at 12:53 PM, Howard Lewis Ship hls...@gmail.com wrote: What is the procedure for getting patches (to clojure-contrib) committed? I've created a couple of issues in Assembla, created and attached patches. What's the next step to get it actually picked up? http://www.assembla.com/spaces/clojure-contrib/tickets/6-Add-set-of-regular-expression-functions http://www.assembla.com/spaces/clojure-contrib/tickets/24?batch=tickets_report_id=3ticket_id=24commit=Go+%C2%BB Is there a particular action to trigger, or person to assign to? -- Howard M. Lewis Ship Creator of Apache Tapestry The source for Tapestry training, mentoring and support. Contact me to learn how I can get you up and productive in Tapestry fast! (971) 678-5210 http://howardlewisship.com -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: java/scala oneliner
:(
map is lazy, so you'll need to wrap it in doall
(dotimes [i 4] (println Happy Birthday ({2 Dear XXX} i To You)))
On Thu, Sep 17, 2009 at 9:17 PM, David Nolen dnolen.li...@gmail.com wrote:
Actually to be fair, here's a Clojure version that uses as little whitespace
as the Scala and Java ones do.
(map #(strHappy Birthday %)(assoc (vec (replicate 4To You))2Dear XXX))
; - 76 chars
On Fri, Sep 18, 2009 at 12:14 AM, David Nolen dnolen.li...@gmail.com
wrote:
Your basic approach seems sound:
(map #(str Happy Birthday %) (assoc (vec (replicate 4 To You)) 2
Dear XXX) - 81 chars including white space
for(int i=0;i4;i++){System.out.println(Happy Birthday +(i==2?Dear
XXX:To You));}) - 88 chars
(1 to 4).map{i=Happy Birthday %s.format(if(i==3)Dear XXXelseTo
You)}.foreach{println(_)} - 95 chars
Anyone have a shorter version? :)
On Thu, Sep 17, 2009 at 11:53 PM, Wilson MacGyver wmacgy...@gmail.com
wrote:
This blog post got me thinking.
http://www.artima.com/weblogs/viewpost.jsp?thread=268561
Basically it contains both a Java one liner and Scala one liner.
Java:
for(int i=0; i4; i++) { System.out.println(Happy Birthday + (i==2
? Dear XXX : To You)); }
Scala:
(1 to 4).map { i = Happy Birthday %s.format(if (i == 3) Dear XXX
else To You) }.foreach { println(_) }
the goal is to generate
Happy Birthday To You
Happy Birthday To You
Happy Birthday Dear XXX
Happy Birthday To You
I started thinking about how to do this in clojure. My first reaction was
to
think of the sentences as two sequences. Uses replicate to generate
them, and map str to join them from two collections.
ie, (map str (replicate 4 Happy Birthday )...
Is there a more clojure way to do it?
because using replicate to generate the 2nd sequence seem like cheating.
ie, replicate 2 To You, 1 Dear XXX, and then To You again.
--
Omnem crede diem tibi diluxisse supremum.
--
And what is good, Phaedrus,
And what is not good—
Need we ask anyone to tell us these things?
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Re: agents swallowing exceptions?
If any exceptions are thrown by an action function, no nested dispatches will occur, and the exception will be cached in the Agent itself. When an Agent has errors cached, any subsequent interactions will immediately throw an exception, until the agent's errors are cleared. Agent errors can be examined with agent-errors and cleared with clear-agent-errors. -- http://clojure.org/agents On Mon, Oct 19, 2009 at 3:41 PM, Raoul Duke rao...@gmail.com wrote: hello, it seems like when i'm running agent stuff via load-file etc. in the repl, exceptions in fns the agent runs don't appear to be logged anywhere, they are seemingly silently swallowed. personally i find that frustrating. is there some way to make them always verbose / spit out to stdout? or am i just crazy and they are showing up and i just don't see them? :} many thanks. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Removing duplication of redis/with-server in every function?
I think the point of this style of api is you just define your functions like (defn one [] ) (defn two [] ) and call the function like (redis/with-server *db* (one) (two)) On Thu, Oct 22, 2009 at 2:44 PM, Radford Smith radscr...@gmail.com wrote: I'm trying out redis-clojure. Right now, my code looks like this: (defn one [] (redis/with-server *db* (...))) (defn two [] (redis/with-server *db* (...))) (defn three [] (redis/with-server *db* (...))) It feels wrong to repeat myself every time I need to use the database. Is there a way to abstract out the (redis/with-server) part? -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Constructing Java Interop calls
you can always just construct the call as a string or as a datastructure and pass it through read/eval On Wed, Oct 28, 2009 at 2:04 PM, Meikel Brandmeyer m...@kotka.de wrote: Hi, Am 28.10.2009 um 20:46 schrieb Tiago Antão: But my point is to be able to construct the method name in runtime. You'll need reflection for that. AFAIU method calls are wired in the bytecode and hence the method name must be known at compile time. Sincerely Meikel -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Constructing Java Interop calls
user= ((eval `(fn [x#] (~(symbol .setFileSelectionMode) x# 1))) jfc) nil user= On Thu, Oct 29, 2009 at 6:38 AM, Meikel Brandmeyer m...@kotka.de wrote: Hi, On Oct 29, 2:07 pm, Tiago Antão tiagoan...@gmail.com wrote: The eval form still shows some problems, if I do this preparation: (import javax.swing.JFileChooser) (def jfc (new JFileChooser)) And then do: user= (.setFileSelectionMode jfc 1) nil All good here, but, if I do the eval variation, user= (eval (list (symbol .setFileSelectionMode) jfc 1)) Another example which shows that eval is not worth the trouble. It is better to use reflection. You cannot embed the JFileChooser as a object into the code. You have to construct it in your eval. (eval ` (let [chooser# (JFileChooser.)] (~(symbol .setFileSelectionMode) chooser# 1) chosser#)). Hopes this helps. Sincerely Meikel -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Constructing Java Interop calls
eval calls read for somethings. 2009/10/30 Tiago Antão tiagoan...@gmail.com: On Thu, Oct 29, 2009 at 1:38 PM, Meikel Brandmeyer m...@kotka.de wrote: All good here, but, if I do the eval variation, user= (eval (list (symbol .setFileSelectionMode) jfc 1)) Another example which shows that eval is not worth the trouble. It is better to use reflection. You cannot embed the JFileChooser as a object into the code. You have to construct it in your eval. (eval ` (let [chooser# (JFileChooser.)] (~(symbol .setFileSelectionMode) chooser# 1) chosser#)). Thanks for all the people that helped. But I just wonder, why? I mean, why one cannot embed an object in the eval code? Tiago -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Creating custom exceptions in clojure gen--class use?
it'd be nice if clojure came with an Exception class that extended IMeta so you could use (catch MetaException e (if (= :my-exception (type e)) do-stuff (throw e))) On Sun, Nov 1, 2009 at 1:07 PM, Meikel Brandmeyer m...@kotka.de wrote: Hi, Am 01.11.2009 um 20:47 schrieb Teemu Antti-Poika: The only way I have managed to achieve this so far is to pre-compile the class using gen-class and a separate compilation step. While googling for solution I came across the old gen-and-load-class, which seemed to do the trick in the old days (?) but is there a current way do achieve the same? gen-class is what you are looking for. You can also use clojure.contrib.condition, but that also requires a compilation step. Be aware: you have to compile the class only once! As long as you don't change the signatures, you can redefine the underlying clojure code for the methods as you like without the need of recompilation. So compilation is a very weak argument against a solution if it solves your problem. Sincerely Meikel -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Applying static java method to seq
(Integer/parseInt 5) is actually (. Integer parseInt 5) which works fine because . is the operator position, and . is a special form On Mon, Nov 2, 2009 at 11:32 AM, ataggart alex.tagg...@gmail.com wrote: If (Integer/parseInt 5) works, then not all functions need be an implementation of IFn; or perhaps more precisely, clojure knows when a call is being made to an IFn vs a static java method. It would be nice for consistency if whatever makes that work also treated Integer/ parseInt as a function with respect to higher-order functions such as map. Even the naive implementation of just automatically wrapping such uses in an anonymous function would go a long way to removing boiler-plate. On Nov 2, 11:03 am, Richard Newman holyg...@gmail.com wrote: Direct references to methods don't work in higher-order functions for some reason. The reason is simply that Java methods are not first-class objects in Clojure. Clojure functions are classes that implement IFn, and thus can be passed around as objects. That's all higher-order functions are. The reason the anonymous function technique works is that it creates a class that implements IFn, which just happens to call the Java method you want. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Baffled by NPE
(f (first items)) = nil ((f (first items)) (for-each f (rest items))) = (nil (for-each f (rest items))) = (.invoke nil (for-each f (rest items))) = calling a method on nil is a NPE lists are function applications On Tue, Nov 3, 2009 at 9:33 AM, Dean Wampler deanwamp...@gmail.com wrote: I'm working the exercises in SICP using Clojure and learning Clojure as I go. I've stumbled across a mystifying NullPointerException. I'm implementing exercise 2.23, where you're supposed to implement a for-each method that takes a function and a list of items. It applies the function to teach item. Here's what I tried. (defn for-each [f items] (if (not (empty? items)) ((f (first items)) (for-each f (rest items) ; line #3 (for-each (fn [x] (println (* x x))) (list 1 2 3 4 5)) Here's the output: 1 4 9 16 25 Exception in thread main java.lang.NullPointerException (ex2.23.clj:0) at clojure.lang.Compiler.eval(Compiler.java:4620) at clojure.lang.Compiler.load(Compiler.java:4934) at clojure.lang.Compiler.loadFile(Compiler.java:4901) at clojure.main$load_script__7261.invoke(main.clj:210) at clojure.main$script_opt__7298.invoke(main.clj:262) at clojure.main$main__7322.doInvoke(main.clj:337) at clojure.lang.RestFn.invoke(RestFn.java:413) at clojure.lang.Var.invoke(Var.java:359) at clojure.lang.AFn.applyToHelper(AFn.java:173) at clojure.lang.Var.applyTo(Var.java:476) at clojure.main.main(main.java:37) Caused by: java.lang.NullPointerException at user$for_each__1.invoke(ex2.23.clj:3) at user$for_each__1.invoke(ex2.23.clj:3) at user$for_each__1.invoke(ex2.23.clj:3) at user$for_each__1.invoke(ex2.23.clj:3) at user$for_each__1.invoke(ex2.23.clj:3) at user$eval__4.invoke(ex2.23.clj:5) at clojure.lang.Compiler.eval(Compiler.java:4604) ... 10 more I tried replacing the list in the last line with a vector. Same result. Suggestions welcome! dean -- Dean Wampler coauthor of Programming Scala (O'Reilly) - http://programmingscala.com twitter: @deanwampler, @chicagoscala Chicago-Area Scala Enthusiasts (CASE): - http://groups.google.com/group/chicagoscala - http://www.meetup.com/chicagoscala/ (Meetings) http://www.linkedin.com/in/deanwampler http://www.polyglotprogramming.com http://aquarium.rubyforge.org http://www.contract4j.org -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Consistency of the API
I don't understand, the error message you get is the error that occurred. the docstring from even? says it throws an exception if the argument is not and integer. I would hope that anyone that has read the docstring for contains? would not use (contains? 'foo 'bar), because, uh, that just makes no sense. I mean that usage does not match what is indicated in the docstring 2009/11/9 Tiago Antão tiagoan...@gmail.com: Hi all, Just a question about the consistency of the API: When one passes a strange (ie, wrong type) object to contains?, say (contains? 'blab 'a) the result is a false. But if one passes the wrong type to, e.g., even?, like (even? 'a) The result is: java.lang.ClassCastException: clojure.lang.Symbol cannot be cast to java.lang.Number (NO_SOURCE_FILE:0) This seems a bit inconsistent, in the sense that one would expect the same behavior for the same kind of error. So the question is: is there any thing less obvious here (at least for me), or is this a real issue with the API? Thanks, Tiago -- The hottest places in hell are reserved for those who, in times of moral crisis, maintain a neutrality. - Dante -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Consistency of the API
the behavior of functions outside of their domain is undefined. I guess I still don't get it. why would you use a function on something outside of its domain? do people just pick functions at random to compose their programs? 2009/11/9 Tiago Antão tiagoan...@gmail.com: On Mon, Nov 9, 2009 at 8:08 PM, Kevin Downey redc...@gmail.com wrote: I don't understand, the error message you get is the error that occurred. Both of them honor their documentation - no doubt. My point is not that, my point is that the behavior is different between the 2 functions for the same kind of issue: What is the rationale for even? and contains? having different behaviors for the exact same error (ie, one throws the other works fine and just returns false on a type error)? From a design perspective this seems to increase the cognitive load to programmers without any (apparent) reason. One would imagine that both functions should have the same behavior for the same kind of error... -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Consistency of the API
what makes functional programming better is the reduction of state. so for example, if I decide that the function call out to contains? is too much overhead in a tight loop, I can just copy and paste the relevant code without being concerned that I might miss some crucial piece of state it twiddles somewhere. The true beauty of functional programming has little directly to do with modes of failure. The beauty of functional programming is transparency of code. I would argue that the kinds of errors you see are an exact result of this transparency, each one is a little X-ray window into the inner workings of the function. On Mon, Nov 9, 2009 at 12:49 PM, Mark Engelberg mark.engelb...@gmail.com wrote: Here's another way to think about it. Why is functional programming better than imperative programming? One common answer to this question is that functional programs are easier to debug. Why? Because in an imperative program, if one part has an error, the error doesn't necessarily manifest in the portion of code that has the error. Instead, a little piece of memory or state can be corrupted in one spot, and then much, much later, an error happens as a result of this inconsistency. Thus the need for sophisticated debuggers and steppers to identify where the corruption happened (since the manifestation of the error doesn't really help you know the source of the problem). However, in a functional program, you have these well-defined pieces that reliably return the same output for a given set of inputs, making it easier to test individual components, and when something produces an error, it's pretty easy to pinpoint the function where things went wrong. Unfortunately, when core functions don't produce errors for invalid inputs, then you have a similar problem as with imperative languages. It becomes rather easy to write a program where the consequence of an error is far removed from the source. I have been told that Erlang programmers have developed a culture where errors are generally not caught or disguised in any way. There's sort of a crash early and crash hard philosophy, to increase the likelihood that a crash will happen in the block of code that is causing the problem and not later. On Mon, Nov 9, 2009 at 12:35 PM, Mark Engelberg mark.engelb...@gmail.com wrote: On Mon, Nov 9, 2009 at 12:32 PM, Kevin Downey redc...@gmail.com wrote: the behavior of functions outside of their domain is undefined. I guess I still don't get it. why would you use a function on something outside of its domain? do people just pick functions at random to compose their programs? Of course they don't pick functions at random, but people do make mistakes. Although I don't mind Clojure's approach, it is reasonable for people to want clear error messages when they use a function improperly. -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: clojure event handling
http://paste.lisp.org/display/87611#2 infinite seq of swing events On Thu, Nov 12, 2009 at 1:48 AM, Jeff Rose ros...@gmail.com wrote: On Nov 12, 1:22 am, nchubrich nicholas.chubr...@gmail.com wrote: I'm curious what the best idiomatic way of handling events is (e.g. receiving a series of messages and dispatching functions on the basis of the messages). One could use the 'experimental' add-watch(er) functions. But it might also be nice to do something stream-oriented, e.g. a doseq on a stream of events. But the trouble is this dies as soon as the events stop arriving. Can event seqs be 'kept alive' somehow (preferably without blocking)? This seems like a pretty basic capability, so I figured it was worth provoking discussion about. Nick. I think the typical way to handle this currently is by using a typical handler function that is called whenever an event is fired. If the events will be long running then you can use agents or a thread pool (executor framework). If you need to dispatch events to other handlers then use multi-methods. It seems that what you are really asking for though, is a way to treat a stream of events as a sequence. This is what they recently introduced in .net land, with the RX framework: http://www.leading-edge-dev.de/?p=501 Given that clojure has a nice library of sequence manipulation and predicate functions, I think doing something similar could be useful. I don't have a clear sense for how it would work though. You could form a pipeline of sequence processing functions that get called whenever a new event is fired, maybe by using a promise that gets fulfilled when the event hits the pipeline? -Jeff -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Proposal: Extend behavior of hash-map
user= (import 'java.util.HashMap)
java.util.HashMap
user= (def m (doto (HashMap.) (.put 'a :a) (.put 'b :b)))
#'user/m
user= m
#HashMap {b=:b, a=:a}
user= (into {} m)
{b :b, a :a}
user= (class *1)
clojure.lang.PersistentArrayMap
user=
On Tue, Nov 17, 2009 at 1:56 PM, Richard Newman holyg...@gmail.com wrote:
Sean,
If the class implements Map, then it already behaves as an associative
data structure in Clojure. E.g.,
(map (fn [[k v]] (println v))
(doto (java.util.HashMap.)
(.put foo bar)
(.put baz noo)))
(get (doto (java.util.HashMap.)
(.put foo bar)
(.put baz noo)) foo)
= bar
That means you can write read-map as
(defn read-map [m]
(merge {} m))
-R
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Re: String to Decimal Conversion
1.1 is not representable as an Integer(Java class, or primitive int) and is not an integer (mathematical sense) so expecting to be representable as one, is kind of... odd. On Sun, Nov 22, 2009 at 4:14 PM, Don josereyno...@gmail.com wrote: I am having a problem converting a string to decimal. I want to convert 1.0 to decimal 1.0. I have tried the java.lang.Integer class use= (Integer/parseInt 1.1) java.lang.NumberFormatException: For input string: 1.1 (NO_SOURCE_FILE:0) But it won't give. It does however work when I run it with 1. Any suggestions would be greatly appreciated. Thank you. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: String to Decimal Conversion
user= (read-string 1.1) 1.1 user= On Sun, Nov 22, 2009 at 4:48 PM, Don josereyno...@gmail.com wrote: Thanks a bunch Richard. On Nov 22, 4:47 pm, Richard Newman holyg...@gmail.com wrote: I am having a problem converting a string to decimal. I want to convert 1.0 to decimal 1.0. For a double (not decimal): (Double/parseDouble 1.1) = 1.1 for a decimal: (BigDecimal. 1.1) 1.1M Note that Clojure has reader support for BigDecimal (the M). -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Question about future
future also uses the same threadpool as agents, so once you call future the threadpool spins up, and just sort of sits around for a while before the jvm decides to exit, which is why the program would sit around for 50 seconds On Wed, Nov 25, 2009 at 10:30 AM, Hong Jiang h...@hjiang.net wrote: Thanks for your replies David and Sean. Yes, I made a mistake thinking that future takes a function and its arguments, so the function was never called in my program. On Nov 25, 8:21 am, David Brown cloj...@davidb.org wrote: On Tue, Nov 24, 2009 at 09:04:38PM -0800, Hong Jiang wrote: Hi all, I'm new to Clojure and playing with small programs. Today I wrote a snippet to figure out how future works: (defn testf [] (let [f (future #(do (Thread/sleep 5000) %) 5) g 7] (+ g @f))) You don't ever evaluate the function containing the sleep, you just create it, and then immediately return 5. Future contains an explicit do, so you can just do the steps in the future: [f (future (Thread/sleep 5000) 5) ... Or, if you want to get the function call in, you'll need to call it: [f (future (#(do (Thread/sleep 5000) %) 5)) ...] David -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Updating Agent
uh, and you just want the agent to reference an empty vector? (send a (comp second list) []) (send a (constantly [])) (send a empty) ... On Tue, Dec 1, 2009 at 2:37 PM, Don josereyno...@gmail.com wrote: I actually came up with this function that takes in an agent and proceeds to pop each item while agent still has items. It's rugged, so maybe someone else will have a better solution. (defn ca [c] (let [cnt (count @c)] (loop [i cnt] (if (not (= i 0)) (do (send c pop) (await c) (recur (dec i))) On Dec 1, 2:27 pm, Don josereyno...@gmail.com wrote: I am having trouble resetting an agent. I created a vector agent as such: (def ce2 (agent [])) I add to this vector by: (send ce2 conj 2) (await ce2) But I am having trouble thinking of a way to reset this agent. I don't believe there is a reset function for agents. Thank You -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Second Lisp to Learn
instant second lisp: just write your own interpreter On Sun, Dec 20, 2009 at 6:39 PM, Jonathan Smith jonathansmith...@gmail.com wrote: Lisp Flavored Erlang is an extremely interesting lisp. in my opinion. You get Erlang, and you also get s-expressions and macros. Common Lisp and Scheme are the obvious choices, I suppose. Learning common lisp I would probably go towards clozure common lisp, or clisp. (SBCL is fine (great, even) on linux, but when i tried it last on windows, there were issues). For scheme, PLT scheme is awesome, but scheme really isn't my thing. On Dec 20, 3:31 pm, Sean Devlin francoisdev...@gmail.com wrote: Hi everyone, After hacking Clojure for a while, I've come to the conclusion that studying a second Lisp would help. So, what do the people here think? What is a good Lisp to study? Are there particular dialects distributions that are interesting? The things that are important to me are: A community at least 1/10th as awesome as this one. Seriously. Libs in Lisp - I want to see if there are ideas worth stealing. Available documentation - I have to be able to read about it, and teach myself online. Thanks, Sean -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Proposal: clojure.io
I think something more abstract would be good. A function or macro where you pass it an IO Spec and it takes care of all the class stuff. (io/read [:bytes :from SOMETHING :as p] (do-stuff-with-a-byte p)) (io/read [:lines :from SOMETHING :as p] (do-stuff-with-a-string p)) (io/read [:lines :from SOMETHING]) ;no :as binding or body, results in a lazy-seq of lines so you can specify the IO behavior you want, and let the implementation map the spec to a class. that being said, you would still want something like duckstreams for interop, and possibly io/read and io/write would be implemented using duckstreams. So I see no harm in pulling duckstreams in. P.S. scopes are great for the lazy-seq case On Fri, Jan 1, 2010 at 1:34 PM, Phil Hagelberg p...@hagelb.org wrote: Sean Devlin francoisdev...@gmail.com writes: 1. I'd recommend adding support for general unix file utilities. I've written some of them myself, and you can review/borrow/steal code from here: http://github.com/francoisdevlin/devlinsf-clojure-utils/blob/master/src/lib/sfd/file_utils.clj These are all one-line wrappers around Java methods. I know Rich has stated that the Clojure philosophy is to avoid such wrappers unless they provide significant additional value. Perhaps this will need to change as people start to write more cross-platform code, but I don't know if we're to that point yet. 2. duck-streams works very well for text, but not binary formats. I know there was discussion about it here: http://groups.google.com/group/clojure/browse_thread/thread/416ca90d3ce2fa3/d64648f34e5c8668 I believe it's the case that reader and writer don't work for binary formats, but copy should. Copying between two files or between a file and a byte array should work fine unless I'm missing something. This should be better-documented though. 3. There should be a brainstorming session to see what objects reader/ writer will dispatch over, and the multimethods improved accordingly. This should probably happen anyway. It covers everything I can think of, but if you've got suggestions let's hear them. -Phil -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
gui repl
I have been playing with a gui repl for clojure: http://github.com/hiredman/Repl instructions are light, but you can check it out, and use lien to jar it up, it is gen-class'ed (but does not require AOt'ing) and has a -main function so you can run it from an uberjar. http://www.thelastcitadel.com/images/Screenshot-Repl.png is a screenshot of me playing with incater the repl is built around swing and jcomponents, so it is possible to display a button in the repl and attach an action listener to it and do neat stuff. I have a sort little video clip of fooling around with the repl http://www.thelastcitadel.com/lab/repl.m4v (http://www.thelastcitadel.com/lab/repl.ogv same video) Anyhoo, it seems like there is an interest in this sort of thing so I wanted to make this available -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: gui repl
ah, well, the differences are: a. this repl is written in Clojure b. this repl can print arbitrary jcomponents, not just text. for example in the screenshot a ChartPanel from JFreeChart is rendered in the repl On Sun, Jan 3, 2010 at 11:42 PM, Albert Cardona sapri...@gmail.com wrote: I built a Swing REPL for clojure some time ago, it's part of Fiji. Launch from Plugins - Scripting - Clojure Interpreter menu command. http://pacific.mpi-cbg.de Code here: http://pacific.mpi-cbg.de/cgi-bin/gitweb.cgi?p=fiji.git;a=blob;f=src-plugins/Clojure/Clojure_Interpreter.java;hb=HEAD Albert -- Albert Cardona http://albert.rierol.net -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: clojure unicode on Windows
java uses local settings, on windows the default encoding is some godawful thing (same on Mac, still godawful, but different) set file.encoding to pick something sane On Wed, Jan 13, 2010 at 1:52 PM, Lukas Lehner lehner.lu...@gmail.com wrote: Hi all The clojure unicode reading, evaluating and printing was discussed already with various results. Let me add one more, and kindly ask for advice if anyone has. OS: Windows 7 clojure 1.1 C:\java -version Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF8 java version 1.6.0_17 Java(TM) SE Runtime Environment (build 1.6.0_17-b04) Java HotSpot(TM) Client VM (build 14.3-b01, mixed mode, sharing) chcp: 437 java clojure.main user= éáú java.lang.Exception: Unable to resolve symbol: ∩┐╜∩┐╜∩┐╜ in this context (NO_SOURCE_FILE:0) You see the problem. chcp: 65001 java clojure.main user= éáú C:\ In this case REPL is killed without any message File unicode-test.clj in unicode: (println (seq (.split őúáé öüü? sdf \\W+))) c:\java clojure.main unicode-test.clj Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF8 Exception in thread main java.lang.Exception: Unable to resolve symbol: in this context (unicode-test.clj:0)0) rest of the error at http://clojure.pastebin.com/m2235d7fb OS: FreeBSD 7.2 clojure 1.1 java -version java version 1.6.0_07 Diablo Java(TM) SE Runtime Environment (build 1.6.0_07-b02) Diablo Java HotSpot(TM) Server VM (build 10.0-b23, mixed mode) locale LANG=en_US.UTF-8 LC_CTYPE=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 LC_TIME=en_US.UTF-8 LC_NUMERIC=en_US.UTF-8 LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8 LC_ALL=en_US.UTF-8 java clojure.main user= éőó java.lang.Exception: Unable to resolve symbol: ó�éőó in this context (NO_SOURCE_FILE:0) user= éőó éőó user= (println éőó) éőó nil user= (def éőó 0) java.lang.Exception: Unable to resolve symbol: �0 in this context (NO_SOURCE_FILE:6) user= better but still not bulletproof testing also the same script like on windows java clojure.main unicode-test.clj ( sfd) No errors :) but of course it did not split the way I wanted... Anyone having better results with unicode and encoding? Preferably on windows. Thank you in advance Lukas -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: clojure unicode on Windows
are you using the repl directly? or wrapped in jline or rlwrap? On Wed, Jan 13, 2010 at 3:02 PM, Lukas Lehner lehner.lu...@gmail.com wrote: Ok, tried to put this at the top of the file, but same bad result on Win (System/setProperty file.encoding UTF8) and actually here http://stackoverflow.com/questions/361975/setting-the-default-java-character-encoding it looks like JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF8 has the same effect, and should be used (and I am using it) Is everybody here running macs and linuxes? :( And, more important now is actually REPL user= (System/setProperty file.encoding UTF8) UTF8 user= éőó ∩┐╜o∩┐╜ user= L On 1/13/2010 11:34 PM, Kevin Downey wrote: java uses local settings, on windows the default encoding is some godawful thing (same on Mac, still godawful, but different) set file.encoding to pick something sane On Wed, Jan 13, 2010 at 1:52 PM, Lukas Lehnerlehner.lu...@gmail.com wrote: Hi all The clojure unicode reading, evaluating and printing was discussed already with various results. Let me add one more, and kindly ask for advice if anyone has. OS: Windows 7 clojure 1.1 C:\java -version Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF8 java version 1.6.0_17 Java(TM) SE Runtime Environment (build 1.6.0_17-b04) Java HotSpot(TM) Client VM (build 14.3-b01, mixed mode, sharing) chcp: 437 java clojure.main user= éáú java.lang.Exception: Unable to resolve symbol: ∩┐╜∩┐╜∩┐╜ in this context (NO_SOURCE_FILE:0) You see the problem. chcp: 65001 java clojure.main user= éáú C:\ In this case REPL is killed without any message File unicode-test.clj in unicode: (println (seq (.split őúáé öüü? sdf \\W+))) c:\java clojure.main unicode-test.clj Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF8 Exception in thread main java.lang.Exception: Unable to resolve symbol: in this context (unicode-test.clj:0)0) rest of the error at http://clojure.pastebin.com/m2235d7fb OS: FreeBSD 7.2 clojure 1.1 java -version java version 1.6.0_07 Diablo Java(TM) SE Runtime Environment (build 1.6.0_07-b02) Diablo Java HotSpot(TM) Server VM (build 10.0-b23, mixed mode) locale LANG=en_US.UTF-8 LC_CTYPE=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 LC_TIME=en_US.UTF-8 LC_NUMERIC=en_US.UTF-8 LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8 LC_ALL=en_US.UTF-8 java clojure.main user= éőó java.lang.Exception: Unable to resolve symbol: ó�éőó in this context (NO_SOURCE_FILE:0) user= éőó éőó user= (println éőó) éőó nil user= (def éőó 0) java.lang.Exception: Unable to resolve symbol: �0 in this context (NO_SOURCE_FILE:6) user= better but still not bulletproof testing also the same script like on windows java clojure.main unicode-test.clj ( sfd) No errors :) but of course it did not split the way I wanted... Anyone having better results with unicode and encoding? Preferably on windows. Thank you in advance Lukas -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: hash literal oddity?
what you are seeing is the transition from arraymap to hashmap
On Mon, Jan 18, 2010 at 6:46 PM, Stuart Halloway
stuart.hallo...@gmail.com wrote:
Is this expected behavior?
{1 this 1 is 1 strange}
= {1 this, 1 is, 1 strange}
(into {} {1 this 1 is 1 strange})
= {1 strange}
{1 this 1 is 1 strange 1 but 1 if 1 I 1 try 1 hard 1
enough}
= {1 enough}
Stu
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Re: Empty defstruct
clojure structs are an optimized version of maps for a set of shared keys. if you don't have a defined set of shared keys you just have a map. so by all means, use a map On Tue, Jan 19, 2010 at 3:52 PM, Andreas Wenger andi.xeno...@googlemail.com wrote: Hi, I would like to know why defstruct without providing any keys (like (defstruct s)) is not allowed (exception: Must supply keys). Let me shortly describe why I think that this would be useful: Imagine you have a defstruct like in Rich's Ants demo: (defstruct cell :food :pher) ;may also have :ant and :home :ant and :home are optional, since they are not often used (Rich actually states in his talk, that this is an advantage compared to Java where we would always have to store null for each of the optional class members). Image, you use (struct-map cell ...) very often in your program. Now, you notice that :food and :pher are also not used very often, and that most times only one or two of the four possible keys are actually used. So you make them all optional: (defstruct cell) ;may have :food, :pher, :ant and :home This is not allowed. You have to remove the whole defstruct, which makes all your (struct-map cell ...) calls useless. This is bad, because you have to replace it everywhere and struct-map has a very nice documentary style you want to use anyway. (Later, when we notice that at least one key is obligatory, we again have to find these places and convert them back to struct-map...) In practice, I had this problem with a struct containing 10 possible keys, where mostly only 1-2 are used in practice. Now I have to remove the whole defstruct... or let at least one arbitrary key be non- optional, which is more a hack than a nice solution. Looking in the PersistentStructMap.java, I found out that allowing structs with no obligatory key would be no problem at all (change 2 lines?). I don't know why it was written that way, but I think here Clojure puts a spoke in me wheel where it just not needed. Any comments? Thanks! Andi -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Empty defstruct
I fail to see how it requires changing a lot of code. it just means you need to change the place where you create your maps. which if you are also type tagging them is a lot of repetitive code, so it should already be factored out into a function, so then you just switch out one function. On Tue, Jan 19, 2010 at 3:59 PM, Andreas Wenger andi.xeno...@googlemail.com wrote: On 20 Jan., 00:56, Kevin Downey redc...@gmail.com wrote: clojure structs are an optimized version of maps for a set of shared keys. if you don't have a defined set of shared keys you just have a map. so by all means, use a map You're talking about the implementation in the background, but I am talking about nice code. I'm aware that defstruct with optional keys introduce a slight overhead compared to normal hashmaps, but that is minimal and defstruct/struct-map is much cleaner and more documentary that a pure hashmap. I can not find a reason why Clojure forbids to make use of this nice feature. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Empty defstruct
how is that not an argument? I'm pretty sure I just used it as one. keep in mind defstruct is largely to be superseded by deftype. http://clojure.org/contributing On Tue, Jan 19, 2010 at 4:10 PM, Andreas Wenger andi.xeno...@googlemail.com wrote: I fail to see how it requires changing a lot of code. it just means you need to change the place where you create your maps. which if you are also type tagging them is a lot of repetitive code, so it should already be factored out into a function, so then you just switch out one function. That's probably true, but you just argue why this inconsistency in Java is not overly severe. But this is no argument for not fixing this inconsistency. Remember, it would only need to change 2 or 3 lines in PersistentStructMap, which is less than the lines I have to fix in my clojure code for only one single instance of this problem. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Empty defstruct
I think your use of workaround is pejorative. And can it even be called a work around if it is a best practice even when there is nothing to work around? On Tue, Jan 19, 2010 at 4:28 PM, Andreas Wenger andi.xeno...@googlemail.com wrote: how is that not an argument? I'm pretty sure I just used it as one. What I wanted to say is that you are completely right, if you say that it is easy to create a workaround. But although doing this is easy, this does not mean that we should not fix this inconsistency (or do you see none?) anyway. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Empty defstruct
empty classes in Java what does that mean? as I said, structs are an optimization on maps, that optimization doesn't work for empty structs, so empty structs of course don't make sense On Wed, Jan 20, 2010 at 12:39 AM, Andreas Wenger andi.xeno...@googlemail.com wrote: I think your use of workaround is pejorative. And can it even be called a work around if it is a best practice even when there is nothing to work around? I just can't understand why throwing an exception should be more useful than returning some object you can actually work with. I wouldn't throw an exception for empty vectors or list either. Why artificially introducing this constraint where it is not necessary at all? Please help me to understand why I am wrong. Why are empty structs in C, empty classes in Java, empty hashmaps in Clojure, why are all of these objects allowed (of course, because it makes sense), but empty defstructs are forbidden by a if-empty-then-exception where it is not necessary or helpful at all? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: REPL vs Script + Regex Problem!
for is lazy, and your code formatting is horrible. On Tue, Feb 2, 2010 at 2:48 PM, Wardrop t...@tomwardrop.com wrote: I've noticed that the output of a script, is often different to the output of the same commands if run on the REPL. This makes sense, but here's a situation which has got me a little confused. I'm trying to run this code as a script... (use '[clojure.contrib.duck-streams]) (for [line (line-seq (reader C:\\filedupes.txt))] (cond ((complement nil?) (re-matches #([0-9]+) byte\(null\)each: line)) (println Byte pattern!) ((complement nil?) (re-matches #.*(\.[0-9a-zA-Z]+) line)) (println File pattern!) ) ) (println Finished!) The problem is, the only output I get is Finished!. If however, I run this on the command line, I get a long list of nil's in amongst the strings Byte pattern! and File pattern!. I expect the nil's not to show when this is run as a script, but why are the aforementioned strings not being output? While you're at it, you may be able to help me with an additional problem I'm trying to tackle. As you can see if the above code, I'm trying to match on certain lines of a text file. I'm using cond to do this with as a switch statement is the only way I know how to achieve what I'm after. Anyway, I not only want the regex to be used in the condition expression, but also want to capture the first sub- match (i.e. what's in the parenthesis inside the regex). What's the best way I can do this, without having to re-run the regex twice. Thanks -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Seattle Clojure meeting
the 11th at Zokas is good for me On Wed, Feb 3, 2010 at 10:07 PM, ajay gopalakrishnan ajgop...@gmail.com wrote: I'm in! But on 11th. I cannot make it on 15th On Wed, Feb 3, 2010 at 7:01 PM, Phil Hagelberg p...@hagelb.org wrote: Hello, clojurists of Seattle. Let's meet! I'm thinking of getting folks together from 7pm to 9pm at Zoka in the University District: http://bit.ly/c9jinW Topics may include Leiningen, deftype/protocols, getting set up with Emacs, or even getting another pair of eyes on that pet project that you've been playing around with recently. I suspect it'll be mostly talking and getting to know people, but bring laptops. I'm thinking of either the 11th or the 15th, depending on what works best for the most people. Let me know if you think you can make it to one or both of these times. -Phil -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Implicit style streams in Clojure
don't use def inside functions, ever. in scheme define is lexically scoped, so you do that sort of thing. clojure is not scheme. if you want a lexically scoped function use a lexical scoping construct like let or letfn. On Mon, Feb 8, 2010 at 12:12 PM, Brenton bashw...@gmail.com wrote: What is the Clojure best practice, if there is one, for writing a function like this: pre (defn integral [integrand initial-value dt] (def --integral (cons initial-value (lazy-seq (add-streams (scale- streams integrand dt) --integral --integral) /pre integrand is a stream of values. I don't like the fact that --integral is visible outside of the integral function but I don't know how else to implement this efficiently. I am using -- here as a naming convention to identify vars that are defined within other functions. Also, what is general feeling about defs inside of functions? Brenton -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.comclojure%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: defn within defn
scheme's define is scoped inside a function. clojure is not scheme. clojure's def (which defn uses) is not lexical or scoped in anyway, it always operates on global names. if you want lexical scope please use one of clojure's lexical scoping constructs, let or letfn. On Wed, Feb 10, 2010 at 1:28 PM, Hozumi fat...@googlemail.com wrote: Hi all. Is it not recommended to use defn within defn? Normal function is faster than the function which has inner function which actually doesn't run. -- (defn aaa1 [] (defn bbb [] 1) 1) (defn aaa2 [] 1) user (time (dotimes [_ 1000] (aaa1))) Elapsed time: 4083.291 msecs nil user (time (dotimes [_ 1000] (aaa2))) Elapsed time: 58.34 msecs nil -- In scheme's case both code have been excuted in the same time. None of clojure code I have seen have inner function. I like inner function because it doesn't consume a name from namespace and make it clear that inner function is only used by outer function. Thanks. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
