Re: is PG's imperative outside-in advice any good?
For those who use clojure.tools.logging, there's also the handy spy
function.
On Tuesday, October 15, 2013 6:41:38 PM UTC-7, dgrnbrg wrote:
If this is something you do often, spyscope is a library I wrote to
simplify this sort of investigation. You can print an expression by writing
#spy/d in front of it. For more information, you can read at
https://github.com/dgrnbrg/spyscope
On Tuesday, October 15, 2013 10:13:58 AM UTC-4, Brian Hurt wrote:
Lifting subexpressions up into lets is actually something I do a lot- for
one very important reason: it lets me insert print statements (or logging
statements) showing the value of the subexpression. So I'll do;
(let [ x (subexpression) ]
(main-expression))
because it lets me do:
(let [ x (subexpression) ]
(println The value of x is x)
(main-expression))
If fact, a lot of times I'll do;
(let [ x (subexpression)
res (main-expression) ]
res)
because it lets me do:
(let [ x (subexpression)
_ (println The value of x is x)
res (main-expression) ]
(println The value of the whole expression is res)
res)
This is of great value in debugging.
Brian
On Tue, Oct 15, 2013 at 9:56 AM, Mikera mike.r.an...@gmail.com wrote:
I certainly prefer giving names to intermediate results with a let
block: having good names and breaking the computation up into logical
chunks makes the code much easier to understand and maintain when you come
back to it later.
PG's example though is bad for different reasons - this is actually
mutating variables in an imperative style, which is definitely bad style
- both in Lisp and Clojure I think. The Clojure equivalent would be to use
atoms (or vars) and mutating them.
let on its own is purely functional, and doesn't have this problem.
On Tuesday, 15 October 2013 20:29:29 UTC+8, Daniel Higginbotham wrote:
I've been going through On Lisp by Paul Graham and on page 33 he
recommends against performing intermediate bindings. Does this advice
hold for Clojure? Here are a couple examples:
;; Common Lisp (from the book)
(defun bad (x)
(let (y sqr)
(setq y (car x))
(setq sqr (expt y 2))
(list 'a sqr)))
(defun good (x)
(list 'a (expt (car x) 2)))
;; Clojure
(defn bad [x]
(let [y (first x)
sqr (expt y 2)]
(list 'a sqr)))
(defn good [x]
(list 'a (expt (first x) 2)))
Paul Graham explains:
The final result is shorter than what we began with, and easier to
understand. In the original code, we’re faced with the final expression
(list 'a sqr), and it’s not immediately clear where the value of sqr comes
from. Now the source of the return value is laid out for us like a road
map.
The example in this section was a short one, but the technique scales
up. Indeed, it becomes more valuable as it is applied to larger
functions.
In clojure you can't do setq of course but I find myself going against
this advice all the time, and I find that it's more important to do so
when
working with larger functions. I think introducing names makes code
clearer. Here's an example from my own code:
(defn create-topic
[params]
(let [params (merge params (db/tempids :topic-id :post-id :watch-id))
topic (remove-nils-from-map (c/mapify params mr/topic-txdata))
watch (c/mapify params mr/watch-txdata)
post (c/mapify params mr/post-txdata)]
{:result (db/t [topic post watch])
:tempid (:topic-id params)}))
To my mind, creating bindings for topic, watch, and post makes
the code easier to understand. When you get to (db/t [topic post watch])
you don't have to deal with as much visual noise to understand exactly
what's going into the transaction.
So, is PG's advice any good?
Thanks!
Daniel
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Re: Do you like the Clojure syntax?
On Wednesday, August 14, 2013 10:14:24 AM UTC-7, Rick Moynihan wrote: Subjectively I found Erlang's syntax pretty horrible (though I like the language itself), Ruby's is superficially beautiful but in practice ambiguous and not without its warts... Have you had a chance to check out Elixir (http://elixir-lang.org/)? It's a language with Ruby-inspired syntax (plus goodies like Clojure-style protocols and true macros) running on the Erlang VM. -- -- 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: clojure.java.jdbc, idiomatic way to use a connection
Does db-transaction work in your case? Evaluates body in the context of a transaction on the specified database connection. The binding provides the database connection for the transaction and the name to which that is bound for evaluation of the body. See db-transaction* for more details. Given a spec, you can use db-transaction like this: (db-transaction [t-db spec] (insert! t-db ...) (update! t-db ...) ...) On Wednesday, August 14, 2013 8:02:52 PM UTC-7, Kyle Cordes wrote: Hello. I've coded quite a lot of JDBC usage in Java, and enough Clojure to know my way around pretty well; yet I've been unable to figure out the following by reading the source and docs for clojure.java.jdbc. I've read http://clojure.github.io/java.jdbc/ and many pages linked from there. The question is: How do I get a connection, then run a series of operations on that same connection? All the API I can find (except for the deprecated, pre-0.3 API) seems to work on a model of: give it a DB connection spec, it connects, runs, and disconnects. Great for playing with a command at a time, less so for doing a series of things that need to happen on the same connection. -- Kyle Cordes http://kylecordes.com -- -- 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: so why it has to be so complicated / Longest Increasing Sub-Seq
This is what I ended up with, which I think is relatively clear and straightforward (but then, I'm not entirely unbiased :) The algorithm is very close to what you described. - Generate all sub-sequences of length 1 - Filter to keep only increasing subsequences - Tack on the empty sequence, which is what needs to be returned if there are no increasing sub-sequences - Sort by length in descending order - Take the first (longest) (fn [coll] (let [increasing? (fn [xs] (apply xs)) n (count coll) sub-seqs (mapcat #(partition % 1 coll) (range 2 (inc n)))] (- sub-seqs (filter increasing?) (cons []) (sort-by count ) first))) On Tuesday, June 12, 2012 12:11:07 PM UTC-7, Andy C wrote: Hi, First a quick disclaimer. Those are my first steps in Clojure so I am not be super accustomed to the language entire landscape and might miss some basics here. However I was able to solve my first 4clojure hard problem https://www.4clojure.com/problem/53 and have some second thoughts after looking up top contributor's solutions as well as mine. Why it has to be so complicated??? Conceptually, you just reduce the list to list of lists using a simple condition . Then you filter items longer then 1. And at the same time you reduce the output to a first longest list. In this case, stack for recursion is really not required, although I did use it in my solution since I could figure out the reduction based way to partition the source sequence. It also seems that imperative solution would be quite straightforward although maintaining at least 4 state variables is not compelling at all. Bottom line, I want to have a idiomatic Clojure solution ... Any insight Thx, Andy -- 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 and the Anti-If Campaign
There's while in clojure.core; would that work? On Tuesday, May 29, 2012 8:13:24 AM UTC-7, Andrew wrote: Thanks for sharing your blog post. Is there an Anti-If alternative to loop/recur in a situation where you have to poll for a condition to be true? (Seems to me that this necessitates some kind of conditional statement) On Thursday, May 24, 2012 5:57:47 AM UTC-4, Dominikus wrote: Three weeks ago I stumbled across the Anti-If Campaign ( http://www.antiifcampaign.com/). An instant later I realized that one could easily re-implement if in Clojure with maps. More interestingly, polymorphic functions can be easily motivated with the help of maps. And this naturally leads to multimethods. If you like, enjoy reading my blogpost on The root of polymorphism: The Anti-If Campaign. It might be an interesting read for Clojure enthusiasts. http://denkspuren.blogspot.de/2012/05/root-of-polymorphism-anti-if-campaign.html Cheers, Dominikus -- 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: Dealing with dynamic header in log file processing
Hi Cliff,
There are at least 2 approaches you can try:
1. Use an atom to store the fields data, updating it whenever you encounter
a #Fields row, and referencing it when processing data rows.
2. Use (reduce) to process the rows, using the accumulator to store both
the current count and fields data. Something like this:
(reduce (fn [{:keys [count fields] :as acc} row]
;; the above de-structuring makes current count and fields
available
(cond
;; if it's a fields row...
(fields-row? row) (let [new-fields :compute-new-fields-here]
(assoc acc :fields new-fields))
;; if it's a data row...
(data-row? row) (let [new-count :compute-new-count-here]
(assoc acc :count new-count
{:count 0 :fields []}
rows)
I think both approaches are equally valid, it's just a matter of which one
appeals to you more. Hope this helps!
On Thursday, April 12, 2012 9:38:31 AM UTC-7, Cliff Mosley wrote:
Prefacing this with being a complete Clojure novice, my question is more
about approach than the actual code required. Like many, I have a few tried
and true examples that I like to work through in each language. In my case,
I have a set of IIS log files that I want to generate usage statistics on.
The hitch in my particular problem is that the log files may or may not
have columns redefined within the file.
As an example
#Software: Microsoft Internet Information Services 6.0
#Version: 1.0
#Date: 2011-05-02 17:42:15
#Software: Microsoft Internet Information Services 6.0
#Version: 1.0
#Date: 2011-05-02 17:42:15
#Fields: date time c-ip cs-username s-ip s-port cs-method cs-uri-stem
cs-uri-query sc-status cs(User-Agent)
2011-05-02 17:42:15 172.22.255.255 - 172.30.255.255 80 GET
/images/picture2.jpg - 200
Mozilla/4.0+(compatible;MSIE+5.5;+Windows+2000+Server)
2011-05-02 17:43:15 172.22.255.255 - 172.30.255.255 80 GET
/images/picture1.jpg - 200
Mozilla/4.0+(compatible;MSIE+5.5;+Windows+2000+Server)
.
.
many more lines
.
.
#Same file, s-ip is now removed so ordinal positions are changed
#Fields: date time c-ip cs-username s-port cs-method cs-uri-stem
cs-uri-query sc-status cs(User-Agent)
2011-05-02 17:48:15 172.22.255.255 - 80 GET /images/picture1.jpg - 200
Mozilla/4.0+(compatible;MSIE+5.5;+Windows+2000+Server)
2011-05-02 17:49:15 172.22.255.255 - 80 GET /images/picture3.jpg - 200
Mozilla/4.0+(compatible;MSIE+5.5;+Windows+2000+Server)
So with the above data, I am trying to get the count of log file hits from
a given cs(User-Agent). In other languages, I would just read in the
#Fields row and continue processing merrily given the most recent order I
encountered moving through the file sequentially. With Clojure, the
immutability of the fields is throwing a wrench for me.
If anyone could give me a nudge in the right direction, I would appreciate
it.
Cliff
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Re: beginner - stuck in dependencies and possibly old versions
Hi Ted, To answer your last question first, each project.clj determines the clojure version used by that project, so you don't really have to worry about old versions interfering or anything. I'm running Lein 1.6.2, which is relatively old, and it defaults new project to 1.3. If yours is using 1.2.1 as the default for new projects, I suspect it may be even more outdated, which may be the cause of your troubles. What is the output if you run lein version, and what OS are you running on? On Wednesday, March 21, 2012 3:41:58 AM UTC-7, ted wrote: Hi all, I am very much a beginner with Clojure and have no experience with Java so please be gentle with me. I've been playing around with numerous incarnations of Lisp but would like to settle on Clojure, however I cannot get my environment sorted. I've installed Leiningen but when I try to do lein plugin install swank-clojure 1.3.1 or lein plugin install lein-oneoff 0.2.0 I get [INFO] unable to find resource 'swank-clojure:swank-clojure:jar:1.3.1' in repository central (http://repo1.maven.org/maven2) (or equivalent for lein-oneoff) I'm sure it is something simple but I have no idea where to look and feel like I'm stuck at the first hurdle. Anybody any idea? I think Leiningen is installed correctly as I can create new projects. I did notice however that the project.clj file as a default refers to clojure 1.2.1 as opposed to clojure 1.3.0. It is very likely that I have old versions of Clojure floating around on my machine as I've played around with Clojure in the past. (I'd like to get rid of the old versions but not sure in which directory(/ies) they have been installed Please let me know if I need to provide more info. Thanks in advance Ted -- 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: Print only by clojure code
Piggy-backing off Mark's answer, if it is log4j that's being used, you can also use log4j.properties to set different logging levels for your Java code vs. your Clojure code (assuming the code are in different packages): http://stackoverflow.com/questions/3569395/filtering-out-log4j-messages-from-third-party-frameworks On Wednesday, February 8, 2012 11:40:45 AM UTC-8, Mark Rathwell wrote: It's logging, and assuming the logging implementation it is using log4j, you can specify the logging properties in a properties file, as system properties, or set the properties in code. The easiest way is to place a file called log4j.properties on the classpath (in the resources directory of your project) containing the following: # set root logger level to OFF (OFF, FATAL, ERROR, WARN, INFO, DEBUG, TRACE, ALL) log4j.rootLogger=OFF On Wed, Feb 8, 2012 at 1:49 PM, Simone Mosciatti mweb@gmail.com wrote: Hi guys, I have developed a very very little application in clojure that use an external lib in java that i prefer do not touch. The problem is that this lib for some weird reason (debug i guess) print at video a bunch of information useless for me, there is any way to avoid this problem, i mean can i just print what the clojure code actually print and not what also the lib in java print ? I'm sorry for my English... -- 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
Re: How to start using clojureCLR?
Hi Erlis, This is the most recent blog entry I've found w.r.t. getting up and running with Clojure CLR: http://www.myclojureadventure.com/2011/10/getting-started-with-clojure-clr.html What I really like about this particular blog is that the author has also written follow-up articles (in Nov. and Dec. of 2011) on how to do things like talk to SQL Server from Clojure CLR and how to call into Clojure CLR from C#. Hope this helps! On Tuesday, December 27, 2011 9:59:09 AM UTC-8, Erlis Vidal wrote: Hi group, I just joined the group and I'm really hypnotized with the Clojure language. Most of the time in my day job I do .Net development but outside of the job I'm always trying to learn and apply other languages and technologies. The curse of the mainstream. I've just finished Stuart's book Programming Clojure and I would like to start introducing some fun in my day to day programming, and when I saw ClojureCLR I was really happy. The point is that I don't know where to start, I haven't found anything that explain how to start working with it. Any blog on how to prepare the environment and start using introducing clojure on my .Net projects ? I'm also curious about ClojureScript, I've been looking CoffeeScript and there are some tools that even integrate with Visual Studio allowing to generate the JavaScript file associate with the CoffeeScript, is there anything like that for ClojureScript? Is it recommended to use ClojureScript in the same scenarios as CoffeeScript or they should serve different purposes? I probably should have two questions, but I see so many opportunities to use Clojure right now that I don't want to miss anything. Thanks in advance and let me know where can I find some information, even if you feel is irrelevant maybe for me is a gold mine. Erlis -- 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: How to start using clojureCLR?
For VS integration, there is the following plugin. I haven't used it myself, so can't offer much help beyond this. Good luck! http://visualstudiogallery.msdn.microsoft.com/fb895809-2ae0-48aa-8a96-3c0d5b8e1fdc/ On Thursday, December 29, 2011 11:17:28 AM UTC-8, Erlis Vidal wrote: Hi! Thanks for the link. I really appreciate it. It looks like the CLR project is really in it first stage. Is someone working on the tools? Any plans to integrate it with VS? thanks! and thanks for the CLR version! On Thu, Dec 29, 2011 at 2:04 PM, Benny Tsai benny...@gmail.com wrote: Hi Erlis, This is the most recent blog entry I've found w.r.t. getting up and running with Clojure CLR: http://www.myclojureadventure.com/2011/10/getting-started-with-clojure-clr.html What I really like about this particular blog is that the author has also written follow-up articles (in Nov. and Dec. of 2011) on how to do things like talk to SQL Server from Clojure CLR and how to call into Clojure CLR from C#. Hope this helps! On Tuesday, December 27, 2011 9:59:09 AM UTC-8, Erlis Vidal wrote: Hi group, I just joined the group and I'm really hypnotized with the Clojure language. Most of the time in my day job I do .Net development but outside of the job I'm always trying to learn and apply other languages and technologies. The curse of the mainstream. I've just finished Stuart's book Programming Clojure and I would like to start introducing some fun in my day to day programming, and when I saw ClojureCLR I was really happy. The point is that I don't know where to start, I haven't found anything that explain how to start working with it. Any blog on how to prepare the environment and start using introducing clojure on my .Net projects ? I'm also curious about ClojureScript, I've been looking CoffeeScript and there are some tools that even integrate with Visual Studio allowing to generate the JavaScript file associate with the CoffeeScript, is there anything like that for ClojureScript? Is it recommended to use ClojureScript in the same scenarios as CoffeeScript or they should serve different purposes? I probably should have two questions, but I see so many opportunities to use Clojure right now that I don't want to miss anything. Thanks in advance and let me know where can I find some information, even if you feel is irrelevant maybe for me is a gold mine. Erlis -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clo...@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+u...@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
Bug in core.match?
Hi all, Ran into what appears to be a bug tonight. This is the simplest example I could come up with: (defn f [xs] (match xs [:a] a [:b b] b [:c] c :else problem!)) [:a] and [:b b] can be matched with no problems, but [:c] can't be matched for some reason: user= (f [:a]) a user= (f [:b 1]) 1 user= (f [:c]) problem! I'm using Clojure 1.3 and core.match 0.2.0-alpha8. -- 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: Bug in core.match?
Done! On Saturday, December 10, 2011 9:08:22 AM UTC-7, David Nolen wrote: Please open a ticket on JIRA with this case - http://dev.clojure.org/jira/browse/MATCH Thanks! David On Sat, Dec 10, 2011 at 5:33 AM, Benny Tsai benny...@gmail.com wrote: Hi all, Ran into what appears to be a bug tonight. This is the simplest example I could come up with: (defn f [xs] (match xs [:a] a [:b b] b [:c] c :else problem!)) [:a] and [:b b] can be matched with no problems, but [:c] can't be matched for some reason: user= (f [:a]) a user= (f [:b 1]) 1 user= (f [:c]) problem! I'm using Clojure 1.3 and core.match 0.2.0-alpha8. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clo...@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+u...@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
Re: Agents vs. Actors
Hi Nils, A while back, I also took a stab* at implementing Erlang-style actors in Clojure, along with solutions for a few classic concurrency problems (Dining Philosophers, Sleeping Barber). I was blown away by how easy it was to implement actor semantics on top of agents. Comparing our respective efforts, I see a lot of room for improvement in mine :) I like how your actors send messages containing the address of the recipient, which seems truer to the actor model. Also, you raise a great point regarding pattern matching; I think that can greatly simplify the message handlers in my code. Looks like it's time for me to get acquainted with core.match :) Thanks for the food for thought! *https://github.com/bitsai/clojure-actors On Friday, December 2, 2011 1:17:43 PM UTC-7, Nils Bertschinger wrote: Hi, how do Clojure agents relate to Erlang actors? To gain some insights, I tried to implement Erlang style message passing between agents. The first version is just a very incomplete sketch (no mailbox, case instead of pattern matching ...), but already shows that it is quite easily doable: https://github.com/bertschi/clojure-stuff/blob/master/src/stuff/actors.clj The idea is that the agent holds a dispatch function which is then called by ! (send) with the message to be send. Somehow it resembles the way closures can be used to implement an object system. Thus, agents seem to be the functional analog of agents: Functional programming Object-oriented programming sequential closure object concurrent agent actors Another great design from Rich Hickey! Clojure is fun and gets better every day ... Thanks, Nils -- 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: Implementing a clojure-only periodic timer...
Overtone's 'at-at' library is a thin Clojure wrapper over ScheduledThreadPoolExecutor with a nice interface. I think you should be able to build a timer on top of it pretty easily. https://github.com/overtone/at-at On Thursday, December 1, 2011 10:17:40 AM UTC-7, Bill Caputo wrote: Hi All, I am currently considering an approach similar to the following for periodically sending an update to an agent and I'm looking for feedback on whether there is anything wrong with it, whether it's idiomatic clojure (sorry I'm in the pro-that-term camp) and whether there are other pure-clojure alternatives I should consider (I also realize there are java-based periodic timers I could use as well): (def *timer* (agent nil)) ; perhaps an atom instead? (defn start-timer [ms a f] (letfn [(tfn [m] (future (do (Thread/sleep ms) (send a f) (send *timer* tfn] (send *timer* tfn))) given an agent: (def data (agent 0)) we could kick off an update every 3 seconds thusly: (start-timer 3000 data #(inc %)) A real implementation would likely have to address further considerations like stopping/cancelling the timer, not using a global for the timer, and what happens if start-timer is called twice, but this is the basic idea I'm considering... feedback welcome, thanks, bill -- 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 Conj extracurricular activities spreadsheet
Does anyone know if the Web and Clojure session will be taking place tonight or another night? -- 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: All subsets of a vector
Another way to do it, using 'reductions': (rest (reductions conj [] a1)) On Wednesday, November 9, 2011 5:47:08 PM UTC-5, Shoeb Bhinderwala wrote: Is there a more elegant/idomatic way to achieve the following result: user= a1 [a b c d] user= (map-indexed (fn [n x] (vec (take (inc n) x))) (take (count a1) (repeat a1))) ([a] [a b] [a b c] [a b c d]) -- 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: All subsets of a vector
That's exactly what 'reductions' does :) On Wednesday, November 9, 2011 6:09:08 PM UTC-5, Alex Baranosky wrote: Does Clojure have the equivalent of Haskell's 'scan' function? (I am on my phone...) Seems like a solution with that would be nice. (scan is like reduce except it keeps all intermediate results) On Nov 9, 2011 5:57 PM, Linus Ericsson oscarlinu...@gmail.com wrote: (map #(vec (take (inc %) a1)) (range (count a1))) does it the lovely map. /Linus 2011/11/9 Shoeb Bhinderwala shoeb.bh...@gmail.com Is there a more elegant/idomatic way to achieve the following result: user= a1 [a b c d] user= (map-indexed (fn [n x] (vec (take (inc n) x))) (take (count a1) (repeat a1))) ([a] [a b] [a b c] [a b c d]) -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clo...@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+u...@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 clo...@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+u...@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
Re: a better way to write this
This is slightly shorter: full-test (fn [element] (every? #(% element) [type-pred bounds-check contact])) On Friday, November 4, 2011 10:51:43 AM UTC-6, HamsterofDeath wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 here's a part of my clojureoids-code: (let [type-pred #() bounds-check #() contact #() full-test (fn [element] (and (type-pred element) (bounds-check element) (contact element)))] (filter full-test (:game-elements @world-atom)) is there a way to write the full-test in a way that doesn't force me to repeat the function constant text pattern inside the and? -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.14 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQIcBAEBAgAGBQJOtBgfAAoJENRtux+h35aGDTAP/RM2mXcu7+HlH0gVHPcZ2bH0 31MEGk5ysup06vgntmxOClaNV9PcxQ1g3bu44YTWDKy3S5RWiD+yB+LkAV0e8xvM p8A64giicfaxI2qncmEpgjodrUn8Yg4vde9X5pQRRaQaWTG56jlLUClorOy62W2q gsvNaehEZa6MZiG6yQOEQ1j0sS438bkmCsqxmHAs2ZmAkb9osTatKECK4sAZRx6l 31KHRFEWx8piiND5vxUGeqlf/CHC3r9VCgBc86q/nnH2CL4cofrkv6mXUYxHikPS AVbT8Qtuonh+twoGLH6t+TYCrVIgiAmnO9IOWFqpdkcX+us3V+ETvXSAVfuf6mCM +pS3Ps0+VndU31/ufZ0pdki/DxlMJiMVPSS1l/Z76671rCQe+dBjFDSU4e+4y9du sj0h1VNQ/tKzQ0jCGb9AF6MHoy51b4dpaqjwuJ4HQscH3L9ruG46dTZs5+IvWb5v 2htp5jQNY25e05qbT2tjPVTKT7C6kZ5S3dMlAfQnQxIaHrIm92IHzq3bhF3xMbgy Yh5sC66y/O4BPZnCvcKY6RF6wBlSZ/vLVOYAasvV89bWanUvv5vgFlNWysNoNF0o eCFhm1NQmvDoqTa0okx3kN5LeoVgGZdfmkEcVNIvVNUFYzht6ffGNaESb3YWFMlO buElt55CDSzWlvkBwqPU =A6jg -END PGP SIGNATURE- -- 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: a better way to write this
Oh that is cool! On Friday, November 4, 2011 12:11:43 PM UTC-6, Paul Mooser wrote: You could try using every-pred to combine your predicates, which I think would be equivalent: (let [full-test (every-pred type-pred bounds-check contact)] ... On Nov 4, 9:51 am, Dennis Haupt d.ha...@googlemail.com wrote: (let [type-pred #() bounds-check #() contact #() full-test (fn [element] (and (type-pred element) (bounds-check element) (contact element)))] (filter full-test (:game-elements @world-atom)) is there a way to write the full-test in a way that doesn't force me to repeat the function constant text pattern inside the and? -- 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: Datestreams
Quite right. Thank you for the reminder. On Wednesday, November 2, 2011 2:51:06 AM UTC-6, Alan Malloy wrote: The call to (set day-nums) should really be pulled out of the inner function to avoid rebuilding the set over and over: (defn day-of-week-stream [ day-nums] (let [day-set (set day-nums)] (filter #(day-set (.. % dayOfWeek get)) (today+all-future- dates On Nov 1, 10:57 pm, Baishampayan Ghose b.g...@gmail.com wrote: On Wed, Nov 2, 2011 at 11:01 AM, Benny Tsai benny...@gmail.com wrote: Untested, since I don't have JodaTime installed, but something like this maybe? (defn day-of-week-stream [ day-nums] (filter #((set day-nums) (.. % dayOfWeek get)) (today+all-future-dates))) This one is a good solution. No need to interleave two streams when you can generate one directly. Regards, BG -- Baishampayan Ghose b.ghose at gmail.com -- 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: Datestreams
Untested, since I don't have JodaTime installed, but something like this maybe? (defn day-of-week-stream [ day-nums] (filter #((set day-nums) (.. % dayOfWeek get)) (today+all-future-dates))) -- 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 Conj extracurricular activities spreadsheet
Please add me for core.logic, Heroku Drinkup, and Jamming with Overtone. -- 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: Flattening a tree
The example tree was not accepted as a valid data structure, so I used this
instead. Hopefully it represents what you had in mind:
(def tree {:parent1
{:relationship1
{:child1 1
:child2 2}
:relationship2
{:child3 3}
:_meta 4}})
I wanted to use clojure.walk to do this, but couldn't figure out how, so
this is what I ended up with instead. 'excluded' should be a set of keys
you want to exclude on the walk.
(defn walk-tree
[tree excluded]
(let [f (fn f [m path]
(apply concat (for [[k v] m]
(cond
(excluded k) nil
(map? v) (f v (conj path k))
:else (list (conj path k))]
(f tree [])))
user= (walk-tree tree #{:_meta})
([:parent1 :relationship1 :child1] [:parent1 :relationship1 :child2]
[:parent1 :relationship2 :child3])
Note that if a path ends with an empty map, that path will not be printed.
Don't know if this is acceptable or not.
(def tree2 {:parent1
{:relationship1
{:child1 {}
:child2 2}
:relationship2
{:child3 3}
:_meta 4}})
user= (walk-tree tree2 #{:_meta})
([:parent1 :relationship1 :child2] [:parent1 :relationship2 :child3])
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Re: clojure.contrib.io, clojure.contrib.http.agent and clojure.contrib.http.connection for Clojure 1.3
Mark McGranaghan and Lee Hinman's clj-http is a nice HTTP library that's fully compatible with Clojure 1.3: https://github.com/dakrone/clj-http -- 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: Randomly select an element from a sorted-set (rand-nth (sorted-set ..))
The reason that (rand-nth (seq (sorted-set 1 2 3))) performs badly on large sets is probably because nth is O(n) on sequences. nth is much much faster on vectors, so I would suggest trying out (rand-nth (vec (sorted-set 1 2 3))) and see if that works for your application. -- 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: Randomly select an element from a sorted-set (rand-nth (sorted-set ..))
On Monday, September 26, 2011 2:58:59 PM UTC-6, Paul Richards wrote: This will replace an O(n) call to nth with an O(n) call to copy into a vector, so still leaving me with O(n). Oops, right :) If you're getting random elements out of the same sorted set multiple times, then it might be still be worth it to pay the cost of vectorizing the set once in exchange for faster subsequent random selections. But if not, then I guess not so much. -- 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 and emacs
You can set lein repl as your inferior lisp program via: M-x describe-variable inferior-lisp-program And as long as you start emacs somewhere in your lein project directory (or M-x cd to it), you'll have all the libraries loaded in your REPL buffer. On Thursday, September 1, 2011 11:03:13 AM UTC-6, melipone wrote: I do like lein repl on the command line. How can I have that in emacs? Basically, if I have a project in Lein, how can I do a (require 'projectname) and have all the libraries loaded in emacs? I'm just using M-x inferior-lisp at this point. I find swank-clojure too complex for right now. Maybe later. TIA melipone -- 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 and emacs
Sorry, what I meant to say in the last line is: And as long as you start emacs somewhere in your lein project directory (or M-x cd to it), you'll automatically be dropped into the main namespace (if you have one defined via :main in project.clj), and the other project namespaces will be available to (require ...) in your REPL buffer. On Saturday, September 3, 2011 7:32:28 PM UTC-6, Benny Tsai wrote: You can set lein repl as your inferior lisp program via: M-x describe-variable inferior-lisp-program And as long as you start emacs somewhere in your lein project directory (or M-x cd to it), you'll have all the libraries loaded in your REPL buffer. On Thursday, September 1, 2011 11:03:13 AM UTC-6, melipone wrote: I do like lein repl on the command line. How can I have that in emacs? Basically, if I have a project in Lein, how can I do a (require 'projectname) and have all the libraries loaded in emacs? I'm just using M-x inferior-lisp at this point. I find swank-clojure too complex for right now. Maybe later. TIA melipone -- 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: Apply concat and mapcat evaluate seqs unnecessarily
This is my attempt to take Meikel's code and extend it to accept arbitrarily many collections as 'mapcat' does: (defn lazy-mapcat [f colls] (lazy-seq (when (every? seq colls) (concat (apply f (map first colls)) (apply lazy-mapcat f (map rest colls)) user= (- (iterate f [0]) (lazy-mapcat identity) (take 1)) (0) user= (defn g [x y] (println computing x + y: (+ x y)) [(+ x y)]) #'user/g user= (take 1 (mapcat g (range) (range))) computing x + y: 0 computing x + y: 2 computing x + y: 4 computing x + y: 6 (0) user= (take 1 (lazy-mapcat g (range) (range))) (computing x + y: 0 0) -- 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: Non-binary tree?
Probably a good idea for get-nodes to handle potential cycles:
(defn get-nodes [from to]
(loop [visited #{}
[x xs] [from]]
(if-not x
visited
(let [new-visited (conj visited x)
neighbors (candidates x to)
new-queue (remove new-visited (concat xs neighbors))]
(recur new-visited
new-queue)
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Re: ClojureScript on Windows
Brenton, thank you for your efforts! I noticed that in the current .bat files, CLASSPATH is directly modified and over-written. Perhaps they should instead use CLJSC_CP like the sh scripts? On Saturday, July 30, 2011 10:10:03 AM UTC-6, Brenton wrote: The problems with paths on Windows have been fixed and ClojureScript now has batch files for cljsc, repl, and repljs. There is also a page in the wiki to help Windows users get started. https://github.com/clojure/clojurescript/wiki/Windows-Setup Support for Windows will come from the community so if you care about this then please do pitch in and help. -- 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: Problem with ClojureScript and Node.js
Thank you for tracking it down and doing the legwork, Anthony :) On Thursday, July 28, 2011 5:50:37 PM UTC-6, Anthony Grimes wrote: Oh! I apologize. I was replying via the google interface and didn't realize it wasn't quoting. Here is a link to the topic for context: https://groups.google.com/d/topic/clojure/ZyVrCxmOFTM/discussion I've also filed a bug here: http://dev.clojure.org/jira/browse/CLJS-43 Sorry. :) On Thursday, July 28, 2011 6:40:39 PM UTC-5, Rich Hickey wrote: Could you please use quoting in your messages? Otherwise they have no context. Thanks, Rich On Jul 28, 2011, at 7:10 PM, Anthony Grimes wrote: Actually, it seems to be caused by this commit: https://github.com/clojure/clojurescript/commit/954e8529b1ec814f40af77d6035f90e93a9126ea If I checkout before that, everything is peachy. I guess I'll submit a bug report. -- 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: Code structure/design problems
Hi Oskar, I just came across this article yesterday, which I thought you may find useful. It's a 4-part series where the author discusses his experience implementing games in a functional style: http://prog21.dadgum.com/23.html He was using Erlang, but I think many of the same ideas apply here as well. Hope this helps. -- 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
Problem with ClojureScript + Node.js
I'm experimenting with ClojureScript on Windows. After applying the patch kindly provided by pmbauer in this thread: https://groups.google.com/d/topic/clojure/kObCK4Ik3tY/discussion ... I was able to get as far as compiling the nodehello.cljs example code from the Quick Start guide. However, when I tried to run the resulting .js file using Node, I got the following error: node.js:195 throw e; // process.nextTick error, or 'error' event on first tick ^ GetConsoleTitleW: The access code is invalid. TypeError: Cannot read property 'prototype' of undefined at Object.anonymous (C:\clojurescript\nodehello.js:14:382) at Module._compile (module.js:420:26) at Object..js (module.js:459:10) at Module.load (module.js:335:31) at Function._load (module.js:294:12) at Array.anonymous (module.js:479:10) at EventEmitter._tickCallback (node.js:187:26) The same error was encountered with both the 0.5.2 and 0.5.1 Windows binaries from http://nodejs.org/dist/. A similar error was thrown when I tried the 0.4.9 and 0.4.8 binaries from http://node-js.prcn.co.cc/: node.js:134 throw e; // process.nextTick error, or 'error' event on first tick ^ WideCharToMultiByte: The data area passed to a system call is too small. TypeError: Cannot read property 'prototype' of undefined at Object.anonymous (/cygdrive/c/clojurescript/nodehello.js:14:382) at Module._compile (module.js:402:26) at Object..js (module.js:408:10) at Module.load (module.js:334:31) at Function._load (module.js:293:12) at Array.anonymous (module.js:421:10) at EventEmitter._tickCallback (node.js:126:26) Has anyone had success using ClojureScript with Node.js, either on Windows or otherwise? -- 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: Problem with ClojureScript + Node.js
On Sunday, July 24, 2011 1:33:47 PM UTC-6, Sean Corfield wrote: That gave me version v0.4.11-pre and it seems to be working just fine with ClojureScript. The build from source option on Windows sounds like it isn't very stable which makes we wonder about the pre-built binaries and why those would be any more stable? :( Thank you for replying, Sean :) It's probably time for me to go back to Ubuntu as my development environment and save myself some pain... -- 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: Problem with ClojureScript and Node.js
Thank you for your response, Urlik. It's good to know someone else saw the same error, on a non-Windows platform, no less. Sean Corfield, responding to an earlier failed attempt by me to post about the problem, said that he was able to use Node with ClojureScript on OSX after following the instructions at https://github.com/joyent/node/wiki/Installation and building Node 0.4.11-pre from source. Perhaps that might work for you as well? If anyone else has experienced this problem, please feel free to chime in! -- 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
Problem with ClojureScript and Node.js
I'm experimenting with the latest build of ClojureScript from github on Windows. I can get as far as compiling nodehello.cljs from the Quick Start guide, but I get the following error when trying to run the compiled .js file with Node: node.js:195 throw e; // process.nextTick error, or 'error' event on first tick ^ GetConsoleTitleW: The access code is invalid. TypeError: Cannot read property 'prototype' of undefined at Object.anonymous (C:\clojurescript\nodehello.js:13:382) at Module._compile (module.js:420:26) at Object..js (module.js:459:10) at Module.load (module.js:335:31) at Function._load (module.js:294:12) at Array.anonymous (module.js:479:10) at EventEmitter._tickCallback (node.js:187:26) I get that error with both 0.5.2 and 0.5.1 binaries from nodejs.org/dist/, and a similar error with the 0.4.9 and 0.4.8 binaries from node-js.prcn.co.cc/: node.js:134 throw e; // process.nextTick error, or 'error' event on first tick ^ WideCharToMultiByte: The data area passed to a system call is too small. TypeError: Cannot read property 'prototype' of undefined at Object.anonymous (/cygdrive/c/clojurescript/nodehello.js:13:382) at Module._compile (module.js:402:26) at Object..js (module.js:408:10) at Module.load (module.js:334:31) at Function._load (module.js:293:12) at Array.anonymous (module.js:421:10) at EventEmitter._tickCallback (node.js:126:26) Has anyone had success with ClojureScript + Node.js, on Windows or otherwise? -- 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: Problem with ClojureScript and Node.js
I should add that I did have to make one change to closure.clj in order to compile nodehello.cljs; I changed the following line in the ns-file-name function: path (string/replace (munge ns) \. java.io.File/separatorChar)] To: path (string/replace (munge ns) \. \/)] -- 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: use of subseq on a vector which I know is already sorted
Hi Sunil, If you know that the input sequence is already sorted, then you can use take-while and drop-while in lieu of subseq. (subseq (sorted-set 1 2 3 4) 3) - (take-while #( % 3) [1 2 3 4]) (subseq (sorted-set 1 2 3 4) = 3) - (take-while #(= % 3) [1 2 3 4]) (subseq (sorted-set 1 2 3 4) 3) - (drop-while #(= % 3) [1 2 3 4]) (subseq (sorted-set 1 2 3 4) = 3) - (drop-while #( % 3) [1 2 3 4]) -- 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: use of subseq on a vector which I know is already sorted
On Monday, July 18, 2011 9:12:05 AM UTC-6, Meikel Brandmeyer wrote: Hi, *snip* However with a different performance promise, I believe. Hi Meikel, I took a look at the source for subseq, and you're right. To be specific, when the comparison operation is either or =, seqFrom allows subseq to get to the elements of interest in O(log n) steps, whereas drop-while needs O(n) steps to do the same. On the other hand, it looks like when the elements of interest are at the beginning of the collection (using or = as comparison operation), subseq and take-while should perform the same, since subseq simply uses take-while to iterate through the elements of interest in this case. To make a long story short, when using or =, use subseq instead of drop-while, especially if the elements of interest are deep in the collection or the same collection will be accessed multiple times. When using or =, subseq and take-while should have the same performance. Does that sound about right? -- 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: Questions About Assoc-in, Dissoc-in, etc.
W.r.t. item 2, would get-in be close to what you're looking for? http://clojuredocs.org/clojure_core/clojure.core/get-in -- 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: help with some code
alist is missing parens around the fn, so it's really a list of 4 elements like so: (1, fn, [x y], (+ x y)) So (second alist) returns just the symbol 'fn. And when you apply a Symbol to a list, the result is the last item in the list (not sure why). To do what you want, alist should be defined like this: (def alist '(1 (fn [x y] (+ x y Also, it seems that the definition of the function needs to be eval'ed first to become an apply-able function. The following returns 4 in my REPL: (apply (eval (second alist)) '(1 3)) -- 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: Help with some code
Hi Paul, I posted an answer to your question in the monads macros discussion. -- 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: help with some code
Nice, yes, that works just as well :) On Tuesday, July 12, 2011 4:09:09 PM UTC-6, LaPingvino wrote: Didn't try, but shoudn't (def alist `(1 ~(fn [x y] (+ x y be better? Then you don't need the eval :) 2011/7/12 Benny Tsai benny...@gmail.com alist is missing parens around the fn, so it's really a list of 4 elements like so: (1, fn, [x y], (+ x y)) So (second alist) returns just the symbol 'fn. And when you apply a Symbol to a list, the result is the last item in the list (not sure why). To do what you want, alist should be defined like this: (def alist '(1 (fn [x y] (+ x y Also, it seems that the definition of the function needs to be eval'ed first to become an apply-able function. The following returns 4 in my REPL: (apply (eval (second alist)) '(1 3)) -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clo...@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+u...@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
Re: help with some code
For that method, you need a back-quote ` (used in macro definition) in front of the 1, not a single quote ' (used to make a form data instead of code). -- 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: Modelling complex data structures (graphs and trees for example)
Hi Colin,
Sorry, a bit late to the party here, but it might be worth taking a look at
Jeffrey
Straszheim's c.c.graph library to see one way of modeling DAG's and
implementing various graph operations (such as topological sort and
computing strongly connected components) in Clojure:
API: http://clojure.github.com/clojure-contrib/graph-api.html
Source:
https://github.com/clojure/clojure-contrib/blob/master/modules/graph/src/main/clojure/clojure/contrib/graph.clj
Note that in the library, graphs are represented by a directed-graph struct
(defined at the top of the source file) with two fields:
- nodes: a collection of the nodes in the graph
- neighbors: a function that takes a node and returns a collection of that
node's neighbors
Since Clojure maps are also functions that will return the value associated
with a key when called with the key, neighbors can simply be a map of nodes
to collections of neighbors.
records are now recommended over structs, so it may be better to define a
directed-graph record:
(defrecord directed-graph [nodes neighbors])
A graph (for example, a graph of two nodes :a and :b that are connected to
each other) can then created via:
(def my-graph (directed-graph. [:a :b] {:a [:b], :b [:a]}))
records can be used in exactly the same way as structs, so this can be used
right away with all the functions defined in the library.
Hope this helps!
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Re: Modelling complex data structures (graphs and trees for example)
Oops, correction: since the library already defines a struct called
directed-graph, it appears that you can't define a record of the same name.
So it'll have to be called something else:
(defrecord graph [nodes neighbors])
(def my-graph (graph. [:a :b] {:a [:b], :b [:a]}))
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Re: Help on a Clojure performance question
Hi Christopher, I ran your code with only one modification, using the time macro to measure the execution time of the mapper function itself: (use ['clojure.java.io :only '(reader)]) (use ['clojure.string :only '(split)]) (defn mapper [lines] (doseq [line lines] (doseq [word (split line #\s+)] (println (str word \t1) (time (mapper (line-seq (reader *in* Processing a file that contained 1 copy of the Hound of Baskerville text took 1.9 seconds. Processing a file that contained 2 copies of the text took 2.8 seconds. Processing a file that contained 4 copies of the text took 3.8 seconds. I did not use cake, but ran mapper.clj via a direct call to the java executable. So I think the times you're seeing is due to either Cake or the way the timing is done. -- 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 way to define the else clause of a cond form?
I believe (d) is considered the idiomatic way*. Btw, I think the second case may not be written correctly; if the intended logic is that 9.75 should be returned when either amount 20 or country = US, the code should look something like this: (cond (= total 20) 8.75 (or ( amount 20) (= country US)) 9.75 :else 10.0) *See: http://dev.clojure.org/display/design/Library+Coding+Standards -- 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 way to define the else clause of a cond form?
Could you please post the entire form, including the code surrounding the cond form (since total, amount, and country need to be defined somewhere)? -- 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 way to define the else clause of a cond form?
On Wednesday, July 6, 2011 9:06:30 PM UTC-6, Tim Robinson wrote: You have some rogue text cluttering your cond statement. Remove the question mark... or whatever this is...  and you'll be fine. That's what I encountered too. Conrad, when I pasted your code into emacs, there was a mystery character between the 0 at the end of the second condition and the :else at the start of the default condition. Once I removed that character (and fixed a spurious newline in the last line), the code evaluated with no problems. -- 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: Data filtering function
This should work: (defn my-filter [coll k] (for [m coll] (get m k))) -- 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: struct sharing same key?
:1 and :3 are keywords, not numbers.
map literals are specified in terms of key-value pairs; for example, in {a b
c d}, a and c are keys, b and d are values. In your person struct, :1 is
only used as a key once, which is why that works. This might help make
things clearer:
(struct person
{:1
english person
[{:2 Andrew D
[{:3 father Andrew D
:3 mother Lisa D}]
:2 Justin M
[{:3 Elisa M}]}]
:1
chinese person
[{:2 Chi chi}]
})
In the first pair, :1 is the key, english person is the value. In the
second pair, the nested vector/map thing is the key, :1 is the value. In
the last pair, chinese person is the key, the vector containing a map is
the value.
With all due respect, the questions you've posted to the list contain some
misunderstandings about certain Clojure fundamentals. May I suggest taking
the time to work through a tutorial or book? It will make life easier going
forward. There are many good choices to pick from, but this is one of my
personal favorites:
http://java.ociweb.com/mark/clojure/article.html
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Re: table vaadin?
That usually means somewhere in the code, an object of class com.vaadin.ui.Table is being used where a function is expected. For example, evaluating this code: (abc 1) ...will result in java.lang.ClassCastException: java.lang.String cannot be cast to clojure.lang.IFn, because a String can't be used as a function. Check the code to see if a com.vaadin.ui.Table object is the first thing in an unquoted list, or passed to a higher-order function in a position where the higher-order function is expecting a function argument. -- 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 to split a collection into predicate passes and failures?
You could also use group-by:
user= (group-by odd? [1 2 3 4 5])
{true [1 3 5], false [2 4]}
The nice thing is that you can also use this with functions that return more
than 2 values:
user= (group-by class [0 nil false])
{java.lang.Integer [0], nil [nil], java.lang.Boolean [false]}
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Re: Properly including clojure-contrib
Hi cmn, A few things: 1. The warnings you see are because the clojure.contrib.string namespace defines several functions that have the same name as core functions (repeat, reverse, etc.). The recommended way to pull in namespaces like that is to do (:require [clojure.contrib.string :as str]), and then the functions can be used via (str/repeat ...), (str/reverse ...), etc. 2. As of 1.2, split is incorporated into clojure.string, so no need to grab clojure.contrib.string just for that function. clojure.string also defines functions with the same name as core functions, so it should be pulled in via (:require [clojure.string :as str]), and split can then be used via (str/split ...). 3. That EOF error is because process-file needs one more closing paren. -- 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-contrib.jar file
I've never built contrib from source, but I believe the repository you'll want to clone from is this one: git://github.com/clojure/clojure-contrib.git -- 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: New to Clojure
Mark Volkmann's Clojure introduction ( http://java.ociweb.com/mark/clojure/article.html) helped me out a great deal when I first started. As he noted at the end, the article focused on Clojure 1.0 features, so some parts are superceded (records are recommended over StructMaps now, for example), and some newer features (such as protocols) are not covered. Nonetheless, I think it's still a great starting point. -- 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: Radically simplified Emacs and SLIME setup
You can grab it here: https://github.com/technomancy/clojure-mode On Saturday, May 21, 2011 6:41:18 PM UTC-6, Tom Hicks wrote: Where does one get clojure-mode 1.9.1? The latest I see on github is 1.7.1. On May 20, 4:06 pm, Phil Hagelberg p@hagelb.org wrote: On May 19, 11:15 pm, Tassilo Horn tas...@member.fsf.org wrote: Do I get you right that the output is the problem that prevents me to get to the SLIME REPL, since you didn't say anything at all about that IllegalArgumentException? I'm not sure what's going on with the IllegalArgumentException. Do you have more than one version of swank in ~/.lein/plugins? If so it's due to a separate bug in Leiningen. But I've fixed the output bug in clojure-mode 1.9.1; see if that helps. -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
Re: Clojure example code snippets
I think there can be multiple words on each line, so they have to be split into words first. Maybe something like: (ns example (:use [clojure.contrib.duck-streams :only (read-lines)])) (let [lines (read-lines file.txt) words (mapcat #(.split % \\s) lines) ing-words (filter (partial re-matches #.*ing) words)] (doseq [ing-word ing-words] (println ing-word))) -- 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: Aw: Clojure example code snippets
I think line-seq needs a java.io.BufferedReader instead of a java.io.FileReader. clojure.java.io has a reader function that constructs a java.io.BufferedReader from a filename, so this worked for me: (ns example (:use [clojure.java.io :only (reader)])) (with-open [rdr (reader file.txt)] (doseq [line (line-seq rdr) word (.split line \\s)] (when (.endsWith word ing) (println word -- 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: Aw: Clojure example code snippets
Oops. Just noticed that the original was not quoted in either of my previous emails, which makes things really confusing. My first reply (the one using read-lines) was an extension of odyssomay/Jonathan's code, and the second (with reader) was an extension of Meikel's code. Sorry guys. -- 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: clj3D, a Clojure 3D Library
Works for me (Chrome 10.0.648.204, Windows XP SP3). -- 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: clj3D, a Clojure 3D Library
Agreed! I installed Shazam just to learn more about this song. It's Blue Train, by John Coltrane. -- 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: (memoize) and recursive functions (Clojure 1.2)
Andreas, Mark, thank you for your suggestions. Both worked splendidly. Just out of curiosity, does memoize in 1.3 behave like the current 1.2 version or the 1.1 version? -- 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: (memoize) and recursive functions (Clojure 1.2)
Fantastic! Thank you Sean. On Tuesday, March 29, 2011 11:37:06 AM UTC-6, Sean Corfield wrote: On Tue, Mar 29, 2011 at 8:31 AM, Benny Tsai benny...@gmail.com wrote: Just out of curiosity, does memoize in 1.3 behave like the current 1.2 version or the 1.1 version? user= (clojure-version) 1.3.0-alpha4 user= (defn f [n] (println f called with n) (if (zero? n) 0 (min (f (dec n)) (f (dec n) (def f (memoize f))#'user/f user= user= (f 2) #'user/f f called with 2 f called with 1 f called with 0 0 user= (f 2) 0 user= (f 3) f called with 3 0 user= (so it works the way you expect) -- Sean A Corfield -- (904) 302-SEAN An Architect's View -- http://corfield.org/ World Singles, LLC. -- http://worldsingles.com/ Railo Technologies, Inc. -- http://www.getrailo.com/ Perfection is the enemy of the good. -- Gustave Flaubert, French realist novelist (1821-1880) -- 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: Can I add the contents of seq to a collection without wrapping?
concat should do the trick: (defn load-sources [ sources] (dosync (alter source-queue concat sources))) -- 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
(memoize) and recursive functions (Clojure 1.2)
I was playing with memoize when I ran into some puzzling behavior. A test case: (defn f [n] (println f called with n) (if (zero? n) 0 (min (f (dec n)) (f (dec n) (def f (memoize f)) *The usage of def to rebind a function to its memoized version is taken from Programming Clojure. The output when I call f with 2: user= (f 2) f called with 2 f called with 1 f called with 0 f called with 0 f called with 1 f called with 0 f called with 0 0 Since f is memoized, my expectation was that I would see f called with 2, f called with 1, f called with 0 each printed just once. Instead, it's as though I didn't memoize f at all. I know I did, because if I call f with 2 again, I get 0 back right away. user= (f 2) 0 This leads me to the second issue: Having evaluated (f 2), I assumed that the results for (f 2), (f 1), and (f 0) are all now available for immediate retrieval. If I call (f 3), I thought I would only see f called with 3 printed and then the result. Instead, this is what I saw: user= (f 3) f called with 3 f called with 2 f called with 1 f called with 0 f called with 0 f called with 1 f called with 0 f called with 0 f called with 2 f called with 1 f called with 0 f called with 0 f called with 1 f called with 0 f called with 0 0 It's as though the recursive calls go to the unmemoized version of the function instead of the memoized one. I did find a way to get the expected behavior: (def g (memoize (fn [n] (println g called with n) (if (zero? n) 0 (min (g (dec n)) (g (dec n))) user= (g 2) g called with 2 g called with 1 g called with 0 0 user= (g 3) g called with 3 0 Up until now, I assumed the first formulation would work with recursive functions as well. Was that incorrect? Is something like the second formulation the only way to memoize recursive functions? -- 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: Good choices for a NoSQL database with Clojure?
A Clojure wrapper for neo4j was recently posted: https://github.com/wagjo/borneo There's also Jiraph, another embedded graph database for Clojure: https://github.com/ninjudd/jiraph -- 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: Loading clojure code during runtime
(read-string) converts a string into a Clojure object, which can then be (eval)ed: (let [f (eval (read-string (fn [x] (* x 2] (map f [1 2 3])) user= (2 4 6) So you could do something like: (let [f (eval (read-string (slurp function.txt)))] (map f [1 2 3])) -- 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: Transforming map entries
My guess is that Clojure's fmap behaves that way because it is modeled
after Haskell's fmap, which only accepts functions that operate only
on the values due to the way fmap (and the Functor typeclass that fmap
belongs to) is modeled in Haskell's type system.
To pass both keys and values to your transforming function, I think
Alan's idea of using 'walk' is the best:
(use '[clojure.walk :only (walk)])
(def my-map {:first john :last smith :age 25})
(defn my-fn [[key value]]
(if (string? value)
[key (.toUpperCase value)]
[key value]))
user= (walk my-fn identity my-map)
{:first JOHN, :last SMITH, :age 25}
On Feb 23, 6:27 am, Chris Maier christopher.ma...@gmail.com wrote:
Can anybody explain why fmap, when operating on an IPersistentMap,
only passes the function the value of the map entry, instead of the
entire map entry (i.e., the key and value pair)? It seems a bit odd
in that all the other implementations of fmap operate on the entire
item in the sequence. Also, I can imagine cases where you'd want to
do some map transformation that also depends on the key (do something
for entries A, B, and C, but something else for entries X, Y, and Z).
I suppose I could use remove-method and then write my own fmap
implementation for IPersistentMap. I'm curious about the design,
though.
Thanks,
Chris
On Tue, Feb 22, 2011 at 6:56 PM, Benny Tsai benny.t...@gmail.com wrote:
There is fmap from clojure.contrib.generic.functor, which expects a
function of arity 1, for just the value:
(use 'clojure.contrib.generic.functor)
(require '[clojure.string :as str])
(def my-map {:first john :last smith :age 25})
(defn my-fn [value]
(if (string? value)
(str/upper-case value)
value))
user= (fmap my-fn my-map)
{:first JOHN, :last SMITH, :age 25}
On Feb 22, 4:23 pm, rob levy r.p.l...@gmail.com wrote:
The usual intuitive options for this are reduce, zipmap, or into. You can
also write a lazily recursive solution. I wonder why there's no function
in
core that lazily re-constructs the map with the results of the function?
It
seems to have been discussed on the list at least once or twice. It seems
like there would have to be two versions of it, one expecting a function
with an arity of one (for just the value) and another expecting an arity of
two (key and value).
On Mon, Feb 21, 2011 at 10:08 PM, yair yair@gmail.com wrote:
I'm hoping this is a dumb question and I've missed something obvious.
I have a map with various key-value pairs and I want to transform some
of the values, e.g.
(def mymap {:first john :last smith :age 25}) and say I want to
change the strings to be upper case.
Right now all I can think of doing is using reduce and passing in an
empty map and the re-associating each key with the (possibly)
transformed value. Is there something like the map function that
takes two parameters, one a function that receives a pair and returns
a new pair, and the other a map, and returns a map that's
reconstituted from those pairs?
Thanks
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Re: Transforming map entries
That is true. Thank you for the reminder. On Feb 23, 10:18 am, Laurent PETIT laurent.pe...@gmail.com wrote: 2011/2/23 Benny Tsai benny.t...@gmail.com My guess is that Clojure's fmap behaves that way because it is modeled Note that it's not Clojure's fmap. fmap is a function in a clojure contrib namespace. The distinction may be important. -- 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: Transforming map entries
There is fmap from clojure.contrib.generic.functor, which expects a
function of arity 1, for just the value:
(use 'clojure.contrib.generic.functor)
(require '[clojure.string :as str])
(def my-map {:first john :last smith :age 25})
(defn my-fn [value]
(if (string? value)
(str/upper-case value)
value))
user= (fmap my-fn my-map)
{:first JOHN, :last SMITH, :age 25}
On Feb 22, 4:23 pm, rob levy r.p.l...@gmail.com wrote:
The usual intuitive options for this are reduce, zipmap, or into. You can
also write a lazily recursive solution. I wonder why there's no function in
core that lazily re-constructs the map with the results of the function? It
seems to have been discussed on the list at least once or twice. It seems
like there would have to be two versions of it, one expecting a function
with an arity of one (for just the value) and another expecting an arity of
two (key and value).
On Mon, Feb 21, 2011 at 10:08 PM, yair yair@gmail.com wrote:
I'm hoping this is a dumb question and I've missed something obvious.
I have a map with various key-value pairs and I want to transform some
of the values, e.g.
(def mymap {:first john :last smith :age 25}) and say I want to
change the strings to be upper case.
Right now all I can think of doing is using reduce and passing in an
empty map and the re-associating each key with the (possibly)
transformed value. Is there something like the map function that
takes two parameters, one a function that receives a pair and returns
a new pair, and the other a map, and returns a map that's
reconstituted from those pairs?
Thanks
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Re: Transforming map entries
I was introduced to fmap by Haskell. Specifically, the (IMHO) most
excellent Learn You a Haskell for Great Good! online tutorial.
Highly recommended!
On Feb 22, 5:04 pm, rob levy r.p.l...@gmail.com wrote:
Yeah, fmap is perfect and definitely the most elegant for the specific
problem described by the OP. I had never heard of that one.
On Tue, Feb 22, 2011 at 6:56 PM, Benny Tsai benny.t...@gmail.com wrote:
There is fmap from clojure.contrib.generic.functor, which expects a
function of arity 1, for just the value:
(use 'clojure.contrib.generic.functor)
(require '[clojure.string :as str])
(def my-map {:first john :last smith :age 25})
(defn my-fn [value]
(if (string? value)
(str/upper-case value)
value))
user= (fmap my-fn my-map)
{:first JOHN, :last SMITH, :age 25}
On Feb 22, 4:23 pm, rob levy r.p.l...@gmail.com wrote:
The usual intuitive options for this are reduce, zipmap, or into. You
can
also write a lazily recursive solution. I wonder why there's no function
in
core that lazily re-constructs the map with the results of the function?
It
seems to have been discussed on the list at least once or twice. It
seems
like there would have to be two versions of it, one expecting a function
with an arity of one (for just the value) and another expecting an arity
of
two (key and value).
On Mon, Feb 21, 2011 at 10:08 PM, yair yair@gmail.com wrote:
I'm hoping this is a dumb question and I've missed something obvious.
I have a map with various key-value pairs and I want to transform some
of the values, e.g.
(def mymap {:first john :last smith :age 25}) and say I want to
change the strings to be upper case.
Right now all I can think of doing is using reduce and passing in an
empty map and the re-associating each key with the (possibly)
transformed value. Is there something like the map function that
takes two parameters, one a function that receives a pair and returns
a new pair, and the other a map, and returns a map that's
reconstituted from those pairs?
Thanks
--
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Re: Euler 40
Hi Marek, I think the (inc) in (decimal-fraction-digits) and the (dec) in (solution) cancel each other out, so the two functions can be simplified a bit to: (defn decimal-fraction-digits [] Returns the lazy sequence of digits in irrational fraction created by concatenating the positive integers (mapcat digits (range))) (defn solution [] (reduce * (take 7 (map #(nth (decimal-fraction-digits) %) (iterate #(* 10 %) 1) On Feb 16, 7:17 am, Marek Stępniowski mstepniow...@gmail.com wrote: On Wed, Feb 16, 2011 at 9:15 AM, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Thanks for everyone who commented on my solution for Euler 28 yesterday. Euler 40 is a bit easier, even more so I'm disappointed with the performance of my solution:(defn euler-40 [n-max] (reduce #(* (Integer/valueOf (str %1)) (Integer/valueOf (str %2))) (let [r (range (inc n-max))] (for [n (iterate #(* % 10) 1) :while ( n n-max)] (nth (apply str r) n) It takes about 4s to find the solution. First of all, I guess the whole Integer/valueOf ceremony doesn't affect performance but could probably be dealt with in a more idiomatic way. Other than that, how could I optimise the presented solution. Hints to other solutions (as long as they're pretty ;)) are also welcome :) My solutionhttps://github.com/zuber/project-euler/blob/master/src/com/stepniowsk... takes ~800 ms on my computer. It's basically the same, but I believe it minimalizes the number of conversions from int to string. Cheers, -- Marek Stępniowskihttp://stepniowski.com -- 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: Project Euler problem 28
My version follows the same algorithm (and so runs in the same amount of time), just arranged differently: (defn corner-nums [n] (for [i (range 4)] (- (* n n) (* i (dec n) (defn sum-all-corner-nums [max-n] (let [ns (range 3 (inc max-n) 2) all-corner-nums (mapcat corner-nums ns)] (apply + 1 all-corner-nums))) Tidbits of interest: * I suck at reading nested code, so I move all but the most trivial lambdas into separate functions, and use (let) liberally to name things. Consequently, my code tends to be more verbose, but I think it makes life easier when revisiting code. * (range) takes an optional step size argument, so generating all odd numbers from 3 to max-n (inclusive) can be done via (range 3 (inc max- n) 2). * (+ 1 (reduce + collection)) can also be written as (apply + 1 collection). * (mapcat) performs a map, then concatenates the results into a single list. I find this quite handy. * It's a purely subjective thing, but I like using (inc x) and (dec x) when incrementing and decrementing x by 1, respectively. On Feb 14, 11:13 pm, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Hi all, Does anyone wanna have a look at my solution for Project Euler Problem 28? (defn diagonal-sum [n-max] (+ 1 (reduce + (map (fn[n] (reduce + (map #(- (* n n) (* % (- n 1))) (range 4 (take-nth 2 (range 3 (+ 2 n-max))) The function does the job. The solution takes about 1.5msec on my machine to compute. I'd like to discuss more performant and/or more idiomatic solutions to that problem :) The parts I'm not quite happy with are the take-nth and range constructs with all the magic numbers in there... Cheers Andreas -- Programs must be written for people to read, and only incidentally for machines to execute. - Abelson Sussman, SICP -- ** Andreas Koestler, Software Engineer Leica Geosystems Pty Ltd 270 Gladstone Road, Dutton Park QLD 4102 Main: +61 7 3891 9772 Direct: +61 7 3117 8808 Fax: +61 7 3891 9336 Email: andreas.koest...@leica-geosystems.com www.leica-geosystems.com* when it has to be right, Leica Geosystems Please consider the environment before printing this email. -- 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: Problems with lazy-xml
Can you post a link to a (sanitized, if need be) sample file? On Feb 11, 1:21 am, Marko Topolnik marko.topol...@gmail.com wrote: Right now I'm working with a 300k-record file, but the code must scale into the millions, and, as I mentioned, it is already spewing OutOfMemoy errors. Also, on a more abstract level, it's just not right to thrash the memory of a concurrent server-side component for absolutely no good reason. -- 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: Problems with lazy-xml
I can confirm that the same thing is happening on my end as well. The XML is parsed lazily: user= (time (let [root (parse-trim (reader huge.xml))] (- root :content type))) Elapsed time: 45.57367 msecs clojure.lang.LazySeq ...but as soon as I try to do anything with the struct map for the DataArea element (second element in root's content), the entire element appears to be parsed eagerly. user= (time (let [root (parse-trim (reader huge.xml))] (- root :content second type))) Elapsed time: 884.905205 msecs clojure.lang.PersistentStructMap I spent some time looking at the source for lazy-xml as well, but wasn't able to locate where the problem lies :( On Feb 11, 3:07 am, Marko Topolnik marko.topol...@gmail.com wrote: http://db.tt/iqTo1Q4 This is a sample XML file with 1000 records -- enough to notice a significant delay when evaluating the code from the original post. Chouser, could you spare a second here? I've been looking and looking at mktree and siblings for two days now and can't for the life of me find out why it would eagerly parse the whole contents of an element as soon as I acces its struct! The code looks perfectly correct. -- 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: Which branch of clojure-hadoop to use?
Thank you, Alex, for the response and your work on the code. And thank you for getting the ball rolling on coordinating clojure-hadoop dev work as well. On Feb 6, 3:58 am, Alex Ott alex...@gmail.com wrote: Hello I'm not working actively on clojure-hadoop, so maybe eslick's and clizzin's forks could be more advanced (although I hadn't looked onto changes). I think, that fragmentation of libraries is not so good thing, so I invite everybody who wants to participate in development to join mailing listhttps://groups.google.com/group/clojure-hadoopand I can give commit rights to repository Benny Tsai at Fri, 4 Feb 2011 20:59:00 -0800 (PST) wrote: BT I have a bunch of older computers sitting at home, and thought I'd put BT them to use for experimenting with clojure-hadoop and swarmiji. BT However, I can't figure out which branch of clojure-hadoop to use. BT Stuart Sierra's branch looks like the canonical one, but hasn't been BT updated since March 2010. alexott's branch looks to be the most BT frequently updated, but there are also more recent branches from BT eslick and clizzin. If someone could shed light on this situation, BT that'd be greatly appreciated! -- With best wishes, Alex Ott, MBAhttp://alexott.blogspot.com/ http://alexott.net/http://alexott-ru.blogspot.com/ Skype: alex.ott -- 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: Lazy seq from input
The blip.tv video of Tom Faulhaber's Lisp, Functional Programming, and the State of Flow talk from Clojure Conj showed me 'fill-queue', which seems like a good fit here. 'fill-queue' is a way to turn input from any source into a lazy sequence. You give it a one-arg function, 'filler-func', which will be called with an argument 'fill' in a separate thread. 'filler-func' is expected to use 'fill' to push input onto a queue. 'fill-queue' returns a lazy sequence of inputs pushed by 'filler-func', and will block when needed. Probably easier to just show it in action: (use '[clojure.contrib.seq-utils :only (fill-queue)]) (defn read-until [prompt input-stream] (let [filler-func (fn [fill] (let [x (.read input-stream)] (when-not (= x -1) (fill (char x)) (recur fill input (fill-queue filler-func)] (take-while #(not= % prompt) input))) Here, 'filler-func' repeatedly reads a char from input-stream and pushes the char onto the queue by calling 'fill' on the char, stopping when -1 is read (signaling end of stream). 'fill-queue' returns a lazy seq of the read chars. 'read-until' then just uses 'take-while' to take the chars up to the prompt (here assuming prompt is a single char). Using me typing in the REPL as the input source: user= (println (read-until \x *in*)) abcdefgx (a b c d e f g) nil You should be able to use this with telnet by passing in the InputStream from the TelnetClient. And if you wish to use a string prompt instead, just replace the call to 'take-while' in 'read-until' with a call to Ken's nifty 'take-until-subseq'. (defn read-until [prompt input-stream] (let [filler-func (fn [fill] (let [input (.read input-stream)] (when-not (= input -1) (fill (char input)) (recur fill input-seq (fill-queue filler-func)] (take-until-subseq input-seq prompt))) user= (println (read-until hey *in*)) abcdefghey (a b c d e f g) nil On Feb 7, 6:09 pm, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Hi all, Is it possible to read from a lazy input sequence? I have a telnet connection using commons.telnet and I want to do something like: (def telnet (TelnetClient.)) (def in (. telnet getInputStream)) ; How do I do this? (def read-until ; read from a lazy input sequence UNTIL prompt is matched and return what's been read [prompt input-stream] ...) Every idea is appreciated :) Cheers Andreas -- 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
Which branch of clojure-hadoop to use?
I have a bunch of older computers sitting at home, and thought I'd put them to use for experimenting with clojure-hadoop and swarmiji. However, I can't figure out which branch of clojure-hadoop to use. Stuart Sierra's branch looks like the canonical one, but hasn't been updated since March 2010. alexott's branch looks to be the most frequently updated, but there are also more recent branches from eslick and clizzin. If someone could shed light on this situation, that'd be greatly appreciated! -- 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: Ridiculously massive slowdown when working with images
Nice! That version runs in 6 milliseconds on my machine, fastest of all the code posted so far. One more idea: use 'unchecked-inc' instead of 'unchecked-add'. This takes it under 3 milliseconds in my tests. (defn java-like [^bytes cpu_array] (let [buffer-size (int buffer-size)] (loop [i (int 0)] (if ( i buffer-size) (let [i2 (unchecked-inc i) i3 (unchecked-inc i2) i4 (unchecked-inc i3) a (aget cpu_array i4)] (amove cpu_array i3 i4) (amove cpu_array i2 i3) (amove cpu_array i i2) (aset cpu_array i a) (recur (unchecked-inc i4))) On Jan 30, 8:15 am, Bill James w_a_x_...@yahoo.com wrote: GrumpyLittleTed wrote: Part of the difference (under 1.2) is due to the (substantial) overhead of accessing the buffer-size var on every iteration. I ran a quick check and using David's version of the code result averaged 17.2ms. Just changing buffer-size to a local with using (let [buffer-size (int 192)]...) the time dropped to an average 3.4ms. Great! Now I remember that that same technique is used in Lua. See long this version takes. (set! *warn-on-reflection* true) (def buffer-size 192) (def array (byte-array buffer-size)) (defmacro add [m n] `(unchecked-add (int ~m) (int ~n))) (defmacro amove[a i j] `(aset ~a ~j (aget ~a ~i))) (defn java-like [^bytes cpu_array] (let [buffer-size (int buffer-size)] (loop [i (int 0)] (if ( i buffer-size) (let [ i2 (add i 1) i3 (add i 2) i4 (add i 3) a (aget cpu_array i4) ] (amove cpu_array i3 i4) (amove cpu_array i2 i3) (amove cpu_array i i2) (aset cpu_array i a) (recur (add i 4))) (dotimes [_ 10] (time (dotimes [_ 1] (java-like array -- 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: Ridiculously massive slowdown when working with images
Combining Ken and David's tips, this version processes a byte-array of
sizd 192 in about 13 milliseconds on my machine:
(def buffer-size 192)
(def array (byte-array buffer-size))
(defn java-like [^bytes cpuArray]
(loop [i (int 0)]
(if ( i buffer-size)
(let [b (aget cpuArray i)
g (aget cpuArray (unchecked-add i (int 1)))
r (aget cpuArray (unchecked-add i (int 2)))
a (aget cpuArray (unchecked-add i (int 3)))]
(aset cpuArray i a)
(aset cpuArray (unchecked-add i (int 1)) b)
(aset cpuArray (unchecked-add i (int 2)) g)
(aset cpuArray (unchecked-add i (int 3)) r)
(recur (unchecked-add i (int 4)))
user= (time (java-like array))
Elapsed time: 13.648662 msecs
Found something interesting when I tried to emulate how Robert's
version aliased 'unchecked-add' as '+':
(defn java-like [^bytes cpuArray]
(loop [i (int 0)]
(if ( i buffer-size)
(let [+ unchecked-add
b (aget cpuArray i)
g (aget cpuArray (+ i (int 1)))
r (aget cpuArray (+ i (int 2)))
a (aget cpuArray (+ i (int 3)))]
(aset cpuArray i a)
(aset cpuArray (+ i (int 1)) b)
(aset cpuArray (+ i (int 2)) g)
(aset cpuArray (+ i (int 3)) r)
(recur (+ i (int 4)))
When I try to compile this, Clojure complains that I'm trying to
rebind i, a primitive local, with a value of the wront type in
'recur'.
It seems that 'unchecked-add' returns a primitive (note that in the
first version, 'recur' happily accepts the return from 'unchecked-add'
without coercion), but when 'unchecked-add' is bound to a new name,
the return gets boxed.
Is this the correct interpretation, or am I missing something?
On Jan 28, 9:06 am, David Nolen dnolen.li...@gmail.com wrote:
On Fri, Jan 28, 2011 at 10:48 AM, Robert McIntyre r...@mit.edu wrote:
I tried to convert this java code line for line to clojure to compare
the speed differences, and boy was I surprised!
public static void ConvertToAWT(byte[] cpuArray){
// Given an array of bytes representing a c-style bgra
image,
// converts to a java style abgr image
int len = java.lang.reflect.Array.getLength(cpuArray);
for (int i = 0; i len; i+=4){
byte b = cpuArray[i+0];
byte g = cpuArray[i+1];
byte r = cpuArray[i+2];
byte a = cpuArray[i+3];
cpuArray[i+0] = a;
cpuArray[i+1] = b;
cpuArray[i+2] = g;
cpuArray[i+3] = r; }}
(defn java-like []
(loop [i (int 0)] (if ( i buffer-size)
(let [ + clojure.core/unchecked-add
b (aget cpuArray i)
g (aget cpuArray (+ 1 i))
r (aget cpuArray (+ 2 i))
a (aget cpuArray (+ 3 i))]
(aset-byte cpuArray i a)
(aset-byte cpuArray (+ 1 i) b)
(aset-byte cpuArray (+ 2 i) g)
(aset-byte cpuArray (+ 3 i) r)
(recur (int (+ i 4)))
(defn clojure-like []
(doall (flatten (map (fn [[b g r a]] [a b g r]) (partition 4 4
cpuArray)
I'm assuming you're using 1.2.0. cpuArray needs to be hinted. All the
literals also need to be hinted. Don't use aset-byte, use aset.
In 1.3.0 you no longer have to hint the literals and you can use the
*unchecked-math* compiler flag instead of redefining unchecked-add as a
local.
David
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Re: Ridiculously massive slowdown when working with images
Try replacing 'aset-byte' with 'aset' and hinting all literals (change 1 to (int 1), etc.) as per David's suggestions. That should reduce the gap even further. On Jan 28, 11:31 am, Robert McIntyre r...@mit.edu wrote: And the plot thickens: This: (defn convert-image [#^bytes cpuArray] (let [unchecked-add clojure.core/unchecked-add len (int (count cpuArray))] (loop [i (int 0)] (if ( i len) (let [ b (byte (aget cpuArray i)) g (byte (aget cpuArray (unchecked-add 1 i))) r (byte (aget cpuArray (unchecked-add 2 i))) a (byte (aget cpuArray (unchecked-add 3 i)))] (aset-byte cpuArray i a) (aset-byte cpuArray (unchecked-add 1 i) b) (aset-byte cpuArray (unchecked-add 2 i) g) (aset-byte cpuArray (unchecked-add 3 i) r) (recur (int (unchecked-add i 4 vs this. (defn convert-image [#^bytes cpuArray] (let [len (java.lang.reflect.Array/getLength cpuArray)] (loop [i (int 0)] (if ( i len) (let [i2 (unchecked-add 1 i) i3 (unchecked-add 2 i) i4 (unchecked-add 3 i) b (byte (aget cpuArray i)) g (byte (aget cpuArray i2)) r (byte (aget cpuArray i3)) a (byte (aget cpuArray i4))] (aset-byte cpuArray i a) (aset-byte cpuArray i2 b) (aset-byte cpuArray i3 g) (aset-byte cpuArray i4 r) (recur (unchecked-add i 4))) The first function takes forever; the second MUCH faster. Upon disassembling the byte-code of the two compiled functions, it does seem like the + was not being inlined. Since the method of reassignment doesn't preserve the metadata, this makes sense. However, my new, modified function is still around 20 times slower than the java version :( I still don't understand what's slowing me down, but I'm much happier that I can get within 20x of java instead of 2x thanks everyone. sincerely, --Robert McIntyre On Fri, Jan 28, 2011 at 1:07 PM, Ken Wesson kwess...@gmail.com wrote: On Fri, Jan 28, 2011 at 12:55 PM, Benny Tsai benny.t...@gmail.com wrote: It seems that 'unchecked-add' returns a primitive (note that in the first version, 'recur' happily accepts the return from 'unchecked-add' without coercion), but when 'unchecked-add' is bound to a new name, the return gets boxed. Is this the correct interpretation, or am I missing something? It's correct. Clojure's compiler inlines certain functions, including clojure.core/unchecked-foo and, when the arity is 2, clojure.core/+ -- but not a bare, un-qualified +, which might (or might not) at runtime refer to clojure.core/+ or clojure.core/unchecked-add or whatever. -- 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
Re: Ridiculously massive slowdown when working with images
Ah I see. Thank you Ken. On Jan 28, 11:07 am, Ken Wesson kwess...@gmail.com wrote: On Fri, Jan 28, 2011 at 12:55 PM, Benny Tsai benny.t...@gmail.com wrote: It seems that 'unchecked-add' returns a primitive (note that in the first version, 'recur' happily accepts the return from 'unchecked-add' without coercion), but when 'unchecked-add' is bound to a new name, the return gets boxed. Is this the correct interpretation, or am I missing something? It's correct. Clojure's compiler inlines certain functions, including clojure.core/unchecked-foo and, when the arity is 2, clojure.core/+ -- but not a bare, un-qualified +, which might (or might not) at runtime refer to clojure.core/+ or clojure.core/unchecked-add or whatever. -- 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: Ridiculously massive slowdown when working with images
Hi Robert, Just out of curiosity, are you running Clojure with the -server option? When I run David's code, -server mode cuts the time for the first run by half, and the time for subsequent runs by a factor of 5. On Jan 28, 12:36 pm, Robert McIntyre r...@mit.edu wrote: David, thanks for your suggestions. I copied your code and tested it out, but on my machine it takes 230 milliseconds while the java version takes about 3. If it's not too much trouble, how long does the java implementation take on your machine? sincerely, --Robert McIntyre On Fri, Jan 28, 2011 at 2:11 PM, David Nolen dnolen.li...@gmail.com wrote: On Fri, Jan 28, 2011 at 2:01 PM, Aaron Cohen aa...@assonance.org wrote: On Fri, Jan 28, 2011 at 1:55 PM, David Nolen dnolen.li...@gmail.com wrote: As a comparison, the following accomplishes the same thing in 1.3.0. (ns test) (set! *unchecked-math* true) (set! *warn-on-reflection* true) (def buffer-size 192) (def array (byte-array buffer-size)) (defn java-like [^bytes cpuArray] (loop [i (int 0)] Is this hint still necessary on 1.3.0? The int cast on 0 was an oversight on my part. It's not necessary. 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 -- 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: Ridiculously massive slowdown when working with images
On my home computer, using the same options, the java version runs in 1.5 milliseconds, and David's 1.2 Clojure version in 16 milliseconds. I'm at a loss as to why you're still seeing such a large gap between the two versions. On Jan 28, 6:16 pm, Robert McIntyre r...@mit.edu wrote: I'm running my JVM with: -verbose:gc -Xmn500M -Xms2000M -Xmx2000M -server sincerely, --Robert McIntyre On Fri, Jan 28, 2011 at 4:24 PM, Benny Tsai benny.t...@gmail.com wrote: Hi Robert, Just out of curiosity, are you running Clojure with the -server option? When I run David's code, -server mode cuts the time for the first run by half, and the time for subsequent runs by a factor of 5. On Jan 28, 12:36 pm, Robert McIntyre r...@mit.edu wrote: David, thanks for your suggestions. I copied your code and tested it out, but on my machine it takes 230 milliseconds while the java version takes about 3. If it's not too much trouble, how long does the java implementation take on your machine? sincerely, --Robert McIntyre On Fri, Jan 28, 2011 at 2:11 PM, David Nolen dnolen.li...@gmail.com wrote: On Fri, Jan 28, 2011 at 2:01 PM, Aaron Cohen aa...@assonance.org wrote: On Fri, Jan 28, 2011 at 1:55 PM, David Nolen dnolen.li...@gmail.com wrote: As a comparison, the following accomplishes the same thing in 1.3.0. (ns test) (set! *unchecked-math* true) (set! *warn-on-reflection* true) (def buffer-size 192) (def array (byte-array buffer-size)) (defn java-like [^bytes cpuArray] (loop [i (int 0)] Is this hint still necessary on 1.3.0? The int cast on 0 was an oversight on my part. It's not necessary. 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 -- 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
Re: Clojure Quizzes?
Hi Randy, You can access a seq of the command line args via the *command-line- args* var. On Jan 16, 3:03 pm, Randy J. Ray randy.j@gmail.com wrote: On 01/12/2011 11:50 PM, Robert McIntyre wrote: They seem to allow you to include anything in a lib directory that you'd want. I sometimes include apache commons-io and clojure-contrib1.2 without any problems. I also included a sql connection library for one of the problems, so it seems fine :) For those puzzles that require command-line processing, have you used a library to do it? Looking in both Programming Clojure and Practical Clojure, the only instruction I can find on handling command-line args involves AOT compilation of your class and definition of a -main method. I'm not sure how well this would work with the submission model that Coderloop uses. I'm afraid I'm still *very* new to Clojure, and while it would be easy (for me) to solve the problems in other languages, the point of the exercise (for me) is to use Coderloop's problems to help myself in learning Clojure... Randy -- Randy J. Ray Sunnyvale, CA http://www.rjray.org rj...@blackperl.com http://www.svsm.org randy.j@gmail.com http://twitter.com/rjray -- 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: thinking parallel programming
In the Hacker News discussion about that talk, someone posted a link to another talk by Guy Steele on the same topic: http://vimeo.com/6624203 ... where he covers the material in somewhat greater depth (the downside being that by the 30-minute mark, I was struggling to keep up with the flow of ideas). I found it to be a nice complement to the talk at infoq. Also, some interesting questions were fielded at the end. On Jan 15, 4:50 pm, Tim Daly d...@axiom-developer.org wrote: Guy Steele recently gave a talk about thinking about parallel programming. For those of us who are looking at Clojure in a parallel setting (e.g. MPI, Hadoop) this might be of interest: http://www.infoq.com/presentations/Thinking-Parallel-Programming -- 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 On Implicit Recursion
Armando's suggested change worked fine for me.
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
(sorted-set f)
(conj (prime-factors (/ n f)) f
user= (prime-factors 600851475143)
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 1471 6857}
On Jan 13, 10:01 am, Vitaly Peressada vit...@ufairsoft.com wrote:
Armando, thanks for a plausible explanation. Here is what happened
after I made the suggested change:
user= (prime-factors 600851475143)
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#CompilerException java.lang.ClassCastException: java.lang.Integer
cannot be cast to clojure.lang.IFn (REPL:91)
I guess this something subtle with unordered vs. sorted-set as
implicit factors accumulator. May be that is why the author of the
solution had to use unordered set followed by (apply max ...).
On Jan 13, 11:23 am, Armando Blancas armando_blan...@yahoo.com
wrote:
A literal set is a unordered hash-set. To get the factors in order
change #{f} for (sorted-set f).
On Jan 13, 7:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
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Re: Question On Implicit Recursion
Good to know, thank you Ben :)
On Jan 13, 10:49 am, B Smith-Mannschott bsmith.o...@gmail.com wrote:
On Thu, Jan 13, 2011 at 17:36, Benny Tsai benny.t...@gmail.com wrote:
(conj) will add items to different places in the collection, depending
on the type of the collection. For a set, this can be at either the
end OR the beginning.
For a (hashed) set, this can be *anywhere* (between existing elements too).
FTFY
// Ben
For this problem, the output is built by:
(conj (conj (conj #{6857} 1471) 839) 71)
which is equivalent to:
(- #{6857} (conj 1471) (conj 839) (conj 71))
The innermost/first conj, (conj #{6857} 1471), sticks 1471 at the end
and produces #{6857 1471}. The next conj sticks 839 at the beginning
and produces #{839 6857 1471}. The final conj sticks 71 at the
beginning and produces the final result of #{71 839 6857 1471}.
When ordering matters, I usually use either (cons), which will always
add to the beginning regardless of the collection type, or use (conj)
with a list (will always add to the beginning) or vector (will always
add to the end).
user= (- '(6857) (conj 1471) (conj 839) (conj 71))
(71 839 1471 6857)
user= (- [6857] (conj 1471) (conj 839) (conj 71))
[6857 1471 839 71]
On Jan 13, 8:09 am, Vitaly Peressada vit...@ufairsoft.com wrote:
The following solution by bmtgred/b for a href=http://clojure-
euler.wikispaces.com/Project Euler Clojure/a problem 003 uses
implicit recursion.
pre
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f
(apply max (prime-factors 600851475143))
/pre
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println n: n , f: f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
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Re: Clojure regexs
For accessing groups in a match, you can use (re-matches). It will
always give the full match as the first element though:
user= (re-matches date-regex 2011 1 13)
[2011 1 13 2011 1 13]
So to replicate the Ruby code's behavior maybe you'll just want (rest
(re-matches date-regex line)).
For ignoring case, putting (?i) at the beginning of the regex worked
for me. (re-find) should give you $1 just fine.
user= (require '[clojure.string :as str])
nil
user= (str/lower-case (re-find #(?i)mon|tue|wed|thu|fri|sat|sun
asdf MON tue))
mon
Hope this helps!
On Jan 13, 7:35 pm, Alex Baranosky alexander.barano...@gmail.com
wrote:
So I am converting some Ruby code I have into CLojure for practice/fun and I
am having trouble finding info via Google.
I want to take something like this from Ruby and do it in Clojure:
DATE_REGEX = /^\s*(\d{4})\s+(\d{1,2})\s+(\d{1,2})/
token =~ DATE_REGEX
[$1, $2, $3]
So far my best guess has been:
(defonce date-regex #^\s*(\d{4})\s+(\d{1,2})\s+(\d{1,2}))
(re-find date-regex line)
but I'm not sure how to access $1, $2, and $3
Another example I'd like to convert is this:
DAYS_OF_WEEK_REGEX = /^\s*(#{Date::DAYS_OF_WEEK.join('|')})/i
token =~ DAYS_OF_WEEK_REGEX
$1.downcase.to_sym
Best attempt is:
(defonce days-of-week-regex #mon|tue|wed|thu|fri|sat|sun(?i))
(re-find days-of-week-regex line)
Here I'd love to know the syntax for ignore-case, along with how to access $1.
Thanks,
Alex
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Re: which IDEs are you all using?
Hi Mark, Could you elaborate on this part? On Jan 11, 8:40 pm, Mark Engelberg mark.engelb...@gmail.com wrote: well. Lots of little things don't work quite right in emacs (at least on Windows), for example, dragging a file onto emacs to edit it, and copying and pasting between apps. I've been using Emacs on Windows for a while now, and haven't run into issues with either of these (yet). With more detail about the issues you faced, perhaps I could offer some help. -- 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: which IDEs are you all using?
Hi Mark, I don't know much about the error msg you encountered, but I think Peter's onto something with the recommendation to set %HOME% yourself to help emacs find your init file(s). This page has good info on how emacs goes about determining your %HOME% directory: http://www.gnu.org/software/emacs/windows/Installing-Emacs.html I believe 23.2 is the latest stable release. With any luck, the intermittent copy/paste problems won't follow you into the newer version :) On Jan 12, 6:49 pm, buckmeist...@gmail.com wrote: Try setting %HOME% to something like c:\home, create the dir if needed, and put your .emacs etc in that folder. I've found that spaces in paths are still often to blame for issues with command line and gnu-esque tools. Thanks, Peter -Original Message- From: Mark Engelberg mark.engelb...@gmail.com Sender: clojure@googlegroups.com Date: Wed, 12 Jan 2011 17:38:00 To: clojure@googlegroups.com Reply-To: clojure@googlegroups.com Subject: Re: which IDEs are you all using? On Wed, Jan 12, 2011 at 8:13 AM, Benny Tsai benny.t...@gmail.com wrote: Hi Mark, Could you elaborate on this part? The version number is: GNU Emacs 23.1.1 (i386-mingw-nt5.1.2600) When I drag a file onto the emacs icon, it starts up, but instead of showing me the file, it says: command-line-1: Cannot open load file: %userprofile%/Application Data/.emacs.d/init.el The cut-and-paste problems are intermittent; I haven't figured out when or why it happens. Thanks for your interest, Mark -- 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 athttp://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
Re: What am I not getting here?
I was typing up an answer, but Jason answered faster and better :)
The only thing I have to add is that 'frequencies' is also in clojure
core as of 1.2.
On Jan 6, 1:13 pm, Jason Wolfe ja...@w01fe.com wrote:
You're not capturing the output of the reduce anywhere; doseq is for
side-effects only.
If you wrapped the doseq in a (def dictionary ...) it would work,
but this is not recommended.
Instead, you should either use nested reductions, or produce a simple
list of tokens first (simpler):
(defn process-file [file-name]
(with-open [rdr (BufferedReader. (FileReader. file-name))]
(reduce #(assoc %1 %2 (inc (get %1 %2 1))) {}
(mapcat #(re-seq #[a-z]+ (.toLowerCase %))
(line-seq rdr)
(def dictionary (process-file src/SpellChecker.clj))
(Untested). Or, using clojure-contrib functions:
(defn process-file [file-name]
(- (clojure.contrib.duck-streams/read-lines file-name)
(mapcat #(re-seq #[a-z]+ (.toLowerCase %)))
clojure.contrib.seq/frequencies))
(also untested).
Cheers, Jason
On Jan 6, 10:49 am, new2clojure miguel.arre...@gmail.com wrote:
Hi,
I am trying to store into a map the frequency of each [a-z]+ word in a
file. When I run this code in the repl the resulting dictionary is
empty. How should I adapt my code to get this functionality right?.
Thank you in advance
(import (java.io BufferedReader FileReader))
(def dictionary {})
(defn process-file [file-name]
(with-open
[rdr (BufferedReader. (FileReader. file-name))]
(doseq
[line (line-seq rdr)]
(reduce #(assoc %1 %2 (inc (get %1 %2 1))) dictionary (re-seq
#[a-z]+ (.toLowerCase line))
(process-file src/SpellChecker.clj)
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Re: My first Clojure program: request for code review
Hi Ken, Sorry for the very late response; I've been away for a friend's wedding. Though I'm not sure if I will end up using this macro frequently, it was highly educational to step through its inner workings. Thank you very much for putting it together. On Dec 23 2010, 11:07 pm, Ken Wesson kwess...@gmail.com wrote: On Fri, Dec 24, 2010 at 12:06 AM, Benny Tsai benny.t...@gmail.com wrote: You're welcome. Sorry I couldn't be of greater help. If you want, I could throw together a quickie macro for grabbing a few items from either end of a seq. Sure, that would be cool :) OK, here goes ... (defmacro ends [[[firsts mid lasts] sequence] body] (let [nl (count lasts)] `(let [s# (seq ~sequence) �...@firsts ~mid] (drop-last ~nl s#) ~lasts (drop (- (count s#) ~nl) s#)] �...@body))) user= (ends [[[a b c] d [e f]] (range 10)] [a b c d e f]) [0 1 2 (3 4 5 6 7) 8 9] As you can see, it expects a binding vector of two items, the second a seqable and the first a vector of first, mid, lasts. Firsts and lasts are vectors of symbols, and mid is a symbol. The first items of the seq are assigned to the firsts symbols, in order; the last items to the lasts, in order; and whatever's left over in the middle to mid. If the sequence is short enough, odd things happen: user= (ends [[[a b c] d [e f]] (range 5)] [a b c d e f]) [0 1 2 nil 3 4] Here the firsts and lasts exhaust the seq; mid ends up nil. Since nil can generally stand in for an empty seq this is OK. user= (ends [[[a b c] d [e f]] (range 4)] [a b c d e f]) [0 1 nil nil 2 3] This is a bit more bothersome. [0 1 2 nil 2 3] might be preferred here. If so the macro needs a slight modification. What do you say? -- 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: My first Clojure program: request for code review
Neat trick! Thanks David :) On Dec 22, 11:23 am, David Nolen dnolen.li...@gmail.com wrote: On Wed, Dec 22, 2010 at 1:22 PM, David Nolen dnolen.li...@gmail.com wrote: On Wed, Dec 22, 2010 at 1:14 PM, Benny Tsai benny.t...@gmail.com wrote: Hi Ken, user= (let [[x y more] [1 2 3 4 5]] [x y more]) [1 2 (3 4 5)] user= (let [[x y z] [1 2 3 4 5]] [x y z]) [1 2 3] user= (let [[_ _ a b] [1 2 3 4 5]] [a b]) [3 4] You can grab any fixed position in this way, as well as a rest that is the tail of the sequence past the last of such. Right, that's true. However, Marek had given two examples of Python tuple unpacking, the first being: first, *middle, last = sequence(...) Which I believe in Python 3 will bind 'first' to the first element, 'last' to the last element, and 'middle' to a sequence of all the elements in the middle. That last part is what I don't know how to do in Clojure. One way: (let [[[f m] l] ((juxt drop-last last) '[a b c d])] [f m l]) ;; [a (b c) c] David Oops typo, ;; [a (b c) d] 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
Re: My first Clojure program: request for code review
On Dec 22, 11:42 am, Ken Wesson kwess...@gmail.com wrote: I don't think Clojure has that. Closest is (let [[f rst] [1 2 3 4 5] l (last rst) m (butlast rst)] [f m l]) Output is [1 (2 3 4) 5] Obviously, using the last element is non-lazy. It may well be that in cases where you'd want to do this you might prefer another data representation. I can imagine some scenarios where it would be nice to do this to sequences. I guess for now, if those should come up in Clojure, we'll just have to jump through a few more hoops. Thank you Ken. -- 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: My first Clojure program: request for code review
Sure, that would be cool :) Sorry for the hijack, Marek! On Dec 23, 5:09 pm, Ken Wesson kwess...@gmail.com wrote: On Thu, Dec 23, 2010 at 7:08 PM, Benny Tsai benny.t...@gmail.com wrote: On Dec 22, 11:42 am, Ken Wesson kwess...@gmail.com wrote: I don't think Clojure has that. Closest is (let [[f rst] [1 2 3 4 5] l (last rst) m (butlast rst)] [f m l]) Output is [1 (2 3 4) 5] Obviously, using the last element is non-lazy. It may well be that in cases where you'd want to do this you might prefer another data representation. I can imagine some scenarios where it would be nice to do this to sequences. I guess for now, if those should come up in Clojure, we'll just have to jump through a few more hoops. Thank you Ken. You're welcome. Sorry I couldn't be of greater help. If you want, I could throw together a quickie macro for grabbing a few items from either end of a seq. -- 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: My first Clojure program: request for code review
Hi Marek, - To sort the nicks by karma in descending order, instead of sorting by the negation of the karma, I used (reverse (sort-by ...)); again, just a subjective thing, makes the intent more clear to me. It does, but doesn't that make it less lazy? To reverse something, it needs to evaluate the whole sequence. I yet have to learn how to deal with lazyness. You're right, I hadn't realized 'reverse' is not lazy (I have a lot to learn about lazyness management myself :)). In this case, though, I don't think it has too much impact, since: 1) The reversing is done just before we evaluate and print everything anyway. 2) 'sort-by' is not lazy either; has to evaluate everything in order to find the first item. FYI, 'reduce' is also not lazy. Great! I was wondering whether Clojure supports something like tuple-unpacking in Python. Does it also support patterned destructuring like: first, *middle, last = sequence(...) -or- first, rest = sequence(...) The latter could be achived by something like `first+rest', I suppose, but don't know the Clojure name for it. The latter is definitely supported; the name after a '' will be bound to the remainder of a sequence: user= (let [[fst rst] [1 2 3]] (println first: fst rest: rst)) first: 1 rest: (2 3) But I don't know of a way to bind the 'middle' elements of a sequence to something. -- 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
