Re: Multiple indexing for vectors/maps
Hello, Am 19.10.2008 um 00:12 schrieb kwatford: I don't think adding this should conflict with any existing code, though I did notice that get currently accepts and apparently ignores one extra parameter. No. It does not ignore the extra parameter! This is a default value, which is returned in case the index is not contained in the vector. user= (def x [:a :b]) #=(var user/x) user= (get x 0 :foo) :a user= (get x 1 :foo) :b user= (get x 2 :foo) :foo See also the help of get: user= (doc get) - clojure/get ([map key] [map key not-found]) Returns the value mapped to key, not-found or nil if key not present. This works also for maps and sets, not only vectors. Sincerely Meikel smime.p7s Description: S/MIME cryptographic signature
CTPOP emulation in JVM
I was reading though Phil Bagwells paper Ideal Hash Trees, when I encountered this paragraph: Note that the performance of the algorithm is seriously impacted by the poor execution speed of the CTPOP emulation in Java, a problem the Java designers may wish to address. I am assuming he means the JVM and not Java. How does this affect Clojure? do you know if it has been fixed? Does it mean that there is a potential performance boost for Clojure waiting in the future? /krukow --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Fibonacci function performance compare between clojure and scala
Clojure's
(defn fib [n]
(if (or (zero? n) (= n 1))
1
(+ (fib (dec n) ) (fib (- n 2)
(time (fib 36))
Elapsed Time: 10475.325226 msecs
24157817
Scala's
def fib(n:Int):Int=if (n==0||n==1)1 else fib(n-1)+fib(n-2)
def time(cal: =Int)={
val beginTime=System.currentTimeMillis
cal
val endTime=System.currentTimeMillis
println(endTime-beginTime)
}
fib(36)
res70:Int=24157817
time(fib(36))
263
Both not tail recursive,both running on Repl (scala's interpreter),but
the difference between two is huge
10475~263
My box : Intel core2 cpu 1.86G，2G mem
Clojure and scala both latest build from svn
any ideas?
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Re: Fibonacci function performance compare between clojure and scala
On Oct 19, 7:49 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
Clojure's
(defn fib [n]
(if (or (zero? n) (= n 1))
1
(+ (fib (dec n) ) (fib (- n 2)
(time (fib 36))
Elapsed Time: 10475.325226 msecs
24157817
Scala's
def fib(n:Int):Int=if (n==0||n==1)1 else fib(n-1)+fib(n-2)
def time(cal: =Int)={
val beginTime=System.currentTimeMillis
cal
val endTime=System.currentTimeMillis
println(endTime-beginTime)}
fib(36)
res70:Int=24157817
time(fib(36))
263
I am not a scala expert but I suspect scala Int maps directly to
java ints.
In clojure, the number are boxed and checked by default IIRC.
This would roughly correspond to BigInt in scala.
For clojure, you could coerce ints to native java types using
(int ..).
Also, unchecked-dec could be used.
Doing this should make the code as fast as java or scala.
There was some discussion along these lines here:
http://groups.google.com/group/clojure/browse_thread/thread/4274ce8bd44664ef#
That said, for most practical uses the default behavior
should be fast enough. Its not considered idiomatic to
use coersion and unchecked operation unless absolutely
necessary.
Parth
Both not tail recursive,both running on Repl (scala's interpreter),but
the difference between two is huge
10475~263
My box : Intel core2 cpu 1.86G，2G mem
Clojure and scala both latest build from svn
any ideas?
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Re: Fibonacci function performance compare between clojure and scala
Scala is sure to use java primitive int type underline, i.e value type and boxed to java Integer when necessarily But why not Clojure auto make this ? gerry On Oct 19, 11:31 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Here is coersion version for Clojure (defn fib [n] (let [n (int n)] (if (or (zero? n) (= n 1)) 1 (+ (fib (dec n) ) (fib (- n 2)) (time (fib 36)) Elapsed time 8848.865149 not much better and how to type hint for a int type? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Fibonacci function performance compare between clojure and scala
There is also a faster way to calculate fibonacci numbers in Clojure
(code taken from from
http://en.wikibooks.org/wiki/Clojure_Programming#Lazy_Fibonacci):
(defn fib-seq []
((fn rfib [a b]
(lazy-cons a (rfib b (+ a b
0 1))
user= (time (take 38 (fib-seq)))
Elapsed time: 0.032965 msecs
(0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765
10946 17711 28657 46368 75025 121393 196418 317811 514229 832040
1346269 2178309 3524578 5702887 9227465 14930352 24157817)
Lauri
2008/10/19 [EMAIL PROTECTED] [EMAIL PROTECTED]:
Clojure's
(defn fib [n]
(if (or (zero? n) (= n 1))
1
(+ (fib (dec n) ) (fib (- n 2)
(time (fib 36))
Elapsed Time: 10475.325226 msecs
24157817
Scala's
def fib(n:Int):Int=if (n==0||n==1)1 else fib(n-1)+fib(n-2)
def time(cal: =Int)={
val beginTime=System.currentTimeMillis
cal
val endTime=System.currentTimeMillis
println(endTime-beginTime)
}
fib(36)
res70:Int=24157817
time(fib(36))
263
Both not tail recursive,both running on Repl (scala's interpreter),but
the difference between two is huge
10475~263
My box : Intel core2 cpu 1.86G，2G mem
Clojure and scala both latest build from svn
any ideas?
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Submitting patches
Rich, I submitted a patch that adds support for exposing protected fields inherited indirectly through the super class in gen-class. No problem if it's unwanted, but would be good to know either way. Suppose the original message should've had patch in the subject line; it's exposing ancestral protected fields with gen-class. Take care, Matt --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Fibonacci function performance compare between clojure and scala
This lazy cached calculate is wonderful ,but i think the benefit from
it mostly due to cache .
On Oct 19, 11:56 pm, Lauri Oherd [EMAIL PROTECTED] wrote:
There is also a faster way to calculate fibonacci numbers in Clojure
(code taken from
fromhttp://en.wikibooks.org/wiki/Clojure_Programming#Lazy_Fibonacci):
(defn fib-seq []
((fn rfib [a b]
(lazy-cons a (rfib b (+ a b
0 1))
user= (time (take 38 (fib-seq)))
Elapsed time: 0.032965 msecs
(0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765
10946 17711 28657 46368 75025 121393 196418 317811 514229 832040
1346269 2178309 3524578 5702887 9227465 14930352 24157817)
Lauri
2008/10/19 [EMAIL PROTECTED] [EMAIL PROTECTED]:
Clojure's
(defn fib [n]
(if (or (zero? n) (= n 1))
1
(+ (fib (dec n) ) (fib (- n 2)
(time (fib 36))
Elapsed Time: 10475.325226 msecs
24157817
Scala's
def fib(n:Int):Int=if (n==0||n==1)1 else fib(n-1)+fib(n-2)
def time(cal: =Int)={
val beginTime=System.currentTimeMillis
cal
val endTime=System.currentTimeMillis
println(endTime-beginTime)
}
fib(36)
res70:Int=24157817
time(fib(36))
263
Both not tail recursive,both running on Repl (scala's interpreter),but
the difference between two is huge
10475~263
My box : Intel core2 cpu 1.86G，2G mem
Clojure and scala both latest build from svn
any ideas?
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Re: offtopic - where are you come from? (poll)
I think it might be more important where people are, where they live, than where they come from. I live in Zürich, Switzerland. On Oct 17, 11:27 am, Rastislav Kassak [EMAIL PROTECTED] wrote: Hello Clojurians, I think after 1st year of Clojure life it's good to check how far has Clojure spread all over the world. So wherever are you come from, be proud and say it. I'm from Slovakia. :) RK --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Fibonacci function performance compare between clojure and scala
Hello, Am 19.10.2008 um 17:56 schrieb Lauri Oherd: There is also a faster way to calculate fibonacci numbers in Clojure (code taken from from http://en.wikibooks.org/wiki/Clojure_Programming#Lazy_Fibonacci): (defn fib-seq [] ((fn rfib [a b] (lazy-cons a (rfib b (+ a b 0 1)) user= (time (take 38 (fib-seq))) Elapsed time: 0.032965 msecs (0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 10946 17711 28657 46368 75025 121393 196418 317811 514229 832040 1346269 2178309 3524578 5702887 9227465 14930352 24157817) This timing is wrong. Since take returns a lazy sequence you only get the timing for the call to take. The sequence is forced later on when the Repl prints it. The correct way is to force the evaluation with doall. user= (time (take 38 (fib-seq))) Elapsed time: 0.055 msecs ... user= (time (doall (take 38 (fib-seq Elapsed time: 0.3 msecs ... Sincerely Meikel smime.p7s Description: S/MIME cryptographic signature
Testing Clojure (was Re: Bug? Strange set equality (r1075))
On Oct 19, 2008, at 5:11 PM, J. McConnell wrote: I've been thinking the same thing for awhile now and I'd love to help contribute to an effort like this. Thanks for getting the idea out there. You're welcome. It seems like clojure.contrib could be a more convenient place to keep this than the wiki. Direct or indirect contributions to clojure.contrib require that the contributed code be written by the contributor and that the contributor have a contributor agreement on file with Rich. Would that be acceptable to people interested in participating? I appreciate the care Rich showed and long view he took in coming up with the Contributor Agreement process. I think it would be a good idea to leverage that process for this effort as well. Discussion of alternative proposals for a good way to do this and place to keep it are welcome. I made a start on this today. I started with the Reader page at clojure.org and started making tests. I'm thinking of a structure like this: Run tests with: (require 'clojure.contrib.test-clojure) The definition of clojure.contrib.test-clojure requires subordinate test namespaces like 'clojure.contrib.test-clojure.Reader 'clojure.contrib.test-clojure.Evaluation 'clojure.contrib.test-clojure.Special-Forms ... with names that correspond to pages on the Clojure web site. After requiring the individual test namespaces, test-clojure runs clojure.contrib.test-is/run-tests on each one. Here's a sample from clojure.contrib.test-clojure. (ns clojure.contrib.test-clojure.Reader (:use clojure.contrib.test-is)) (deftest t-Symbols (is (= 'abc (symbol abc))) (is (= '*+!-_? (symbol *+!-_?))) (is (= 'abc:def:ghi (symbol abc:def:ghi))) (is (= 'abc/def (symbol abc def))) (is (= 'abc.def/ghi (symbol abc.def ghi))) (is (= 'abc/def.ghi (symbol abc def.ghi))) (is (= 'abc:def/ghi:jkl.mno (symbol abc:def ghi:jkl.mno))) (is (instance? clojure.lang.Symbol 'alphabet)) ) ; additional tests to flesh out (deftest t-Numbers) (deftest t-Characters) (deftest t-nil) (deftest t-Booleans) (deftest t-Keywords) (deftest t-Lists) (deftest t-Vectors) (deftest t-Maps) (deftest t-Sets) (deftest t-Quote) (deftest t-Character) (deftest t-Comment) (deftest t-Meta) (deftest t-Deref) (deftest t-Regex) (deftest t-Metadata) (deftest t-read) and a run: user= (require 'clojure.contrib.test-clojure) Testing #Namespace: clojure.contrib.test-clojure.Reader Ran 18 tests with 10 assertions. 0 failures, 0 exceptions. nil user= (Currently the number of tests exceeds the number of assertions by so much because of the placeholders.) Tesing Clojure is a big project and will take a lot of work over time. There many pieces and many interactions among them to test. The hope is that having it available will allow Rich to make changes with an even higher degree of confidence that they didn't have unintended consequences and to support efforts like Chouser's ClojureScript to bring Clojure to new platforms Discussion and suggestions are welcome. --Steve --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Swank-clojure: slime-eval-print-last-expression failing.
Hello, I am a common lisp programmer and I use Slime extensively. I am looking into using Clojure for an upcoming project (I have experience with ABCL, but it is too slow) and I have clojure and swank-clojure installed. Unfortunately slime-eval-print-last-expression (C-j in *slime-scratch*) is failing (evaluation aborted), I think because it uses asynchronous evaluation. Is this a known issue or a regression? Is it fixable? I really want to be able to adapt my workflow for working with clojure, and I use C-j all the time. All code except for Emacs itself is current as of 2 hours ago. The behaviour was duplicated by a member of #clojure. Hope you can help, -Luke --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Testing Clojure (was Re: Bug? Strange set equality (r1075))
I like this idea and I would be willing to contribute. On Oct 19, 6:43 pm, Stephen C. Gilardi [EMAIL PROTECTED] wrote: On Oct 19, 2008, at 5:11 PM, J. McConnell wrote: I've been thinking the same thing for awhile now and I'd love to help contribute to an effort like this. Thanks for getting the idea out there. You're welcome. It seems like clojure.contrib could be a more convenient place to keep this than the wiki. Direct or indirect contributions to clojure.contrib require that the contributed code be written by the contributor and that the contributor have a contributor agreement on file with Rich. Would that be acceptable to people interested in participating? I appreciate the care Rich showed and long view he took in coming up with the Contributor Agreement process. I think it would be a good idea to leverage that process for this effort as well. Discussion of alternative proposals for a good way to do this and place to keep it are welcome. I made a start on this today. I started with the Reader page at clojure.org and started making tests. I'm thinking of a structure like this: Run tests with: (require 'clojure.contrib.test-clojure) The definition of clojure.contrib.test-clojure requires subordinate test namespaces like 'clojure.contrib.test-clojure.Reader 'clojure.contrib.test-clojure.Evaluation 'clojure.contrib.test-clojure.Special-Forms ... with names that correspond to pages on the Clojure web site. After requiring the individual test namespaces, test-clojure runs clojure.contrib.test-is/run-tests on each one. Here's a sample from clojure.contrib.test-clojure. (ns clojure.contrib.test-clojure.Reader (:use clojure.contrib.test-is)) (deftest t-Symbols (is (= 'abc (symbol abc))) (is (= '*+!-_? (symbol *+!-_?))) (is (= 'abc:def:ghi (symbol abc:def:ghi))) (is (= 'abc/def (symbol abc def))) (is (= 'abc.def/ghi (symbol abc.def ghi))) (is (= 'abc/def.ghi (symbol abc def.ghi))) (is (= 'abc:def/ghi:jkl.mno (symbol abc:def ghi:jkl.mno))) (is (instance? clojure.lang.Symbol 'alphabet)) ) ; additional tests to flesh out (deftest t-Numbers) (deftest t-Characters) (deftest t-nil) (deftest t-Booleans) (deftest t-Keywords) (deftest t-Lists) (deftest t-Vectors) (deftest t-Maps) (deftest t-Sets) (deftest t-Quote) (deftest t-Character) (deftest t-Comment) (deftest t-Meta) (deftest t-Deref) (deftest t-Regex) (deftest t-Metadata) (deftest t-read) and a run: user= (require 'clojure.contrib.test-clojure) Testing #Namespace: clojure.contrib.test-clojure.Reader Ran 18 tests with 10 assertions. 0 failures, 0 exceptions. nil user= (Currently the number of tests exceeds the number of assertions by so much because of the placeholders.) Tesing Clojure is a big project and will take a lot of work over time. There many pieces and many interactions among them to test. The hope is that having it available will allow Rich to make changes with an even higher degree of confidence that they didn't have unintended consequences and to support efforts like Chouser's ClojureScript to bring Clojure to new platforms Discussion and suggestions are welcome. --Steve --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Testing Clojure (was Re: Bug? Strange set equality (r1075))
Ditto. I've been thinking about this for a few weeks and would be happy to help out where I can. On Sun, Oct 19, 2008 at 6:22 PM, Paul Barry [EMAIL PROTECTED] wrote: I like this idea and I would be willing to contribute. On Oct 19, 6:43 pm, Stephen C. Gilardi [EMAIL PROTECTED] wrote: On Oct 19, 2008, at 5:11 PM, J. McConnell wrote: I've been thinking the same thing for awhile now and I'd love to help contribute to an effort like this. Thanks for getting the idea out there. You're welcome. It seems like clojure.contrib could be a more convenient place to keep this than the wiki. Direct or indirect contributions to clojure.contrib require that the contributed code be written by the contributor and that the contributor have a contributor agreement on file with Rich. Would that be acceptable to people interested in participating? I appreciate the care Rich showed and long view he took in coming up with the Contributor Agreement process. I think it would be a good idea to leverage that process for this effort as well. Discussion of alternative proposals for a good way to do this and place to keep it are welcome. I made a start on this today. I started with the Reader page at clojure.org and started making tests. I'm thinking of a structure like this: Run tests with: (require 'clojure.contrib.test-clojure) The definition of clojure.contrib.test-clojure requires subordinate test namespaces like 'clojure.contrib.test-clojure.Reader 'clojure.contrib.test-clojure.Evaluation 'clojure.contrib.test-clojure.Special-Forms ... with names that correspond to pages on the Clojure web site. After requiring the individual test namespaces, test-clojure runs clojure.contrib.test-is/run-tests on each one. Here's a sample from clojure.contrib.test-clojure. (ns clojure.contrib.test-clojure.Reader (:use clojure.contrib.test-is)) (deftest t-Symbols (is (= 'abc (symbol abc))) (is (= '*+!-_? (symbol *+!-_?))) (is (= 'abc:def:ghi (symbol abc:def:ghi))) (is (= 'abc/def (symbol abc def))) (is (= 'abc.def/ghi (symbol abc.def ghi))) (is (= 'abc/def.ghi (symbol abc def.ghi))) (is (= 'abc:def/ghi:jkl.mno (symbol abc:def ghi:jkl.mno))) (is (instance? clojure.lang.Symbol 'alphabet)) ) ; additional tests to flesh out (deftest t-Numbers) (deftest t-Characters) (deftest t-nil) (deftest t-Booleans) (deftest t-Keywords) (deftest t-Lists) (deftest t-Vectors) (deftest t-Maps) (deftest t-Sets) (deftest t-Quote) (deftest t-Character) (deftest t-Comment) (deftest t-Meta) (deftest t-Deref) (deftest t-Regex) (deftest t-Metadata) (deftest t-read) and a run: user= (require 'clojure.contrib.test-clojure) Testing #Namespace: clojure.contrib.test-clojure.Reader Ran 18 tests with 10 assertions. 0 failures, 0 exceptions. nil user= (Currently the number of tests exceeds the number of assertions by so much because of the placeholders.) Tesing Clojure is a big project and will take a lot of work over time. There many pieces and many interactions among them to test. The hope is that having it available will allow Rich to make changes with an even higher degree of confidence that they didn't have unintended consequences and to support efforts like Chouser's ClojureScript to bring Clojure to new platforms Discussion and suggestions are welcome. --Steve --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Newbie question on the use of functional hash maps
If you're interested only in counting the number of unique words, then
you don't even need a map. You can get by with a set, like this:
(defn unique-words-in-file
[file]
(count (set (split-on-whitespace (slurp file)
slurp reads file into a String object in memory. The hypothetical
split-on-whitespace takes a String and returns a collection of word
objects. set takes a collection and produces a set of the elements in
that collection. count counts the number of elements in the set.
If, on the other hand, you wanted a map from each word in the file to
the number of times that it appears, you might do it like this:
(defn word-counts
[file]
(reduce
(fn [map word] (assoc map word (inc (get map word 0
{}
(split-on-whitespace (slurp file
The reduce starts with the empty map {}, and then for each word in the
file, produces a new map by invoking the anonymous function supplied
as the first argument to reduce.
You could also get the same result with a list comprehension, using
for:
(defn word-counts
[file]
(apply merge-with +
(for [word (split-on-whitespace (slurp file))]
{word 1})))
Here we emit a map for each word in the file, mapping that word to 1.
Then we merge all the maps together, using + when two maps contain the
same key. This function has a small bug: it throws an exception if
the file contains no words. To fix it, you would insert an additional
argument to apply, the empty map {}.
On Oct 19, 9:16 pm, Tom Emerson [EMAIL PROTECTED] wrote:
Hi all,
I have a somewhat embarassing newbie question on the use of hash maps
in a functional environment.
Consider a little utility that counts the number of unique words in a
file. A hash map mapping strings to integers is the obvious data
structure for this, but the fact that (assoc) returns a new map each
time it is called is tripping me up: since I can't define a 'global'
hash map to accumulate the counts, do you pass one around in a
function? or do you structure the code a different way? This is a
difference from what I would do in Common Lisp, where I would just
have a global that is used for the collection.
Thanks in advance for your wisdom.
-tree
--
Tom Emerson
[EMAIL PROTECTED]://www.dreamersrealm.net/~tree
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Re: offtopic - where are you come from? (poll)
Austin, Texas, USA. On Oct 17, 9:18 am, Eric Rochester [EMAIL PROTECTED] wrote: Atlanta, Georgia, US On Fri, Oct 17, 2008 at 5:27 AM, Rastislav Kassak [EMAIL PROTECTED]wrote: Hello Clojurians, I think after 1st year of Clojure life it's good to check how far has Clojure spread all over the world. So wherever are you come from, be proud and say it. I'm from Slovakia. :) RK --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: Clojure + Terracotta
Rich, I'm the tech lead for the transparency team at Terracotta and this is not exactly correct. For example, while you can read clustered state outside of a clustered lock, it's possible for the tc memory manager to clear that state at any time, allowing you to see a null instead of the real value. Generally, if you're not reading under at least a read lock, you can see nulls. Now, all is not lost because an immutable data structure requires only a read lock and read locks can be checked out to all the nodes in the cluster and used locally as a write will never occur. Read locks like that will be served locally without crossing the network and will not generate tc transactions. So, this will be a really cheap lock to get even in the cluster. Maps (especially CHM) are also a fairly specialized case as we heavily instrument and modify the internal behavior. Map impls like HashMap, Hashtable, and CHM are all partial in tc, meaning that the keys must always be in all nodes but values are faulted lazily as needed. Currently, volatiles are not really treated any differently than other non-volatile fields - we require that they be accessed under a clustered lock. The whole purpose of volatile isn't really possible with Terracotta so we can't really do anything special. We do have some internal support for automatically wrapping volatiles in clustered locks but haven't surfaced that out to our config file yet. You're correct on the CAS - in general the stuff that really makes single VM concurrency fly (like fine-grained locks with lightweight impls like CAS) are awful for clustering. For things like sequences, it's generally better to use checked out blocks of ids. We've got an implementation of this if you want it (it's pretty straightforward). If that's not sufficient, I'm sure we could come up with some other solution. I have a keen interest in Clojure (awesome stuff Rich) and obviously also Terracotta. If only I had another 5 hrs/day, I'd spend it on Clojure/TC integration. :) I (and others at Terracotta) are certainly happy to answer questions and help where we can. Probably best to ask on our mailing lists as everyone in eng monitors the user and dev lists: http://www.terracotta.org/confluence/display/wiki/Mailing+Lists Alex Miller On Oct 18, 7:50 am, Rich Hickey [EMAIL PROTECTED] wrote: On Fri, Oct 17, 2008 at 8:01 PM, Luc Prefontaine [EMAIL PROTECTED] wrote: I am not very far from tackling this issue. In our bus messaging system, we are using Terracotta with some Java components and it's a matter of weeks before we start to investigate how we can bridge Clojure and Terracotta. A customer asked us about some new functionality today and I see a need to fill the Terracotta/Clojure gap somehow. I'll comeback toward the end of November with some proposal. Any comments Rich about how you would see this integration and what Clojure semantics you would like to share through Terracotta ? I might enlarge the scope beyond what we need in our system even if not all the pieces are delivered in the very short term. There are lots of potential synergies. I think that one key benefit of using Clojure is that the immutable data structures can be shared, yet read outside of locks. As you know, Terracotta requires shared objects to be accessed under a lock. However, once the object has been propagated, it need not be acceessed under a lock iff it is immutable. This was one of the first things I verified with Terracotta. So, for instance, you can do the normal Terracotta cache thing and put Clojure's persistent data structures in a ConcurrentHashMap shared root. Once you pull one out of the map, you can use it henceforth without locking - a huge benefit IMO. Plus, since the data structures share structure, updates are also efficient. A current hitch, which I am looking to enhance anyway, is that some of the data structures do lazy hash creation with volatile caches. In proc this is no problem, nor out of proc since the hash value is a pure function of the immutable structure value, but I think Terracotta may not be happy with the volatile members. I have already on my todo list moving to incrementally calculated hash values (had to wait for the unification of hash logic with java.util's, now done). Of course, this leaves you with ConcurrentHashMap's last-one-in-wins, no coordinated activity semantics. When that's not good enough, you'll want to try STM refs + transactions. Here too, I think a lot is possible. As I've said, I once had this working, but haven't tracked whether or not all mechanisms I am using are supported by Terracotta. Underneath the STM are all standard Java concurrency things - reentrant locks, wait/notify, java.util.concurrent.atomic stuff etc. To the extent these are supported, it should function correctly right away. That said, there's one aspect of the STM I think could be tweaked for a clustering situation. The
Re: Beginners (and idiomatic Clojure)
On Oct 20, 12:30 am, Paul Barry [EMAIL PROTECTED] wrote: Krukow, I agree, it would help to have a resource for learning Clojure. For now, my best advice is to pick a real project to start working and then specific questions in the IRC room, #clojure on irc.freenode.net. Within a few months, we'll have the beta book:http://www.pragprog.com/titles/shcloj/programming-clojure Wow, I wasn't expecting a book this early. Hope the quality will be as high as the other material on the web -- will definitely pre-order it. Thanks for the hint. /krukow --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
