#clojure – 2009-09-21

2009-09-21

01:56	tomoj	so say you want to read n bytes from an InputStream. is (take n (repeatedly #(.read input-stream)) safe?
01:58	tomoj	I guess repeatedly isn't chunked, huh
02:06	mudphone`	Hey folks was wondering if anyone could help me with a question about this anonymous function syntax: (fn []> (+ 1 2))
02:06	mudphone`	I'm wondering what the ">" is for.
02:06	hiredman	does nothin
02:06	hiredman	typo or a mispaste
02:07	mudphone`	ah, must be a typo, since I got it from a book
02:08	mudphone`	So, i guess the follow-up is, why isn't it cause an error?
02:08	mudphone`	doesn't it
02:09	hiredman	> is a valid value
02:09	hiredman	,>
02:09	clojurebot	#<core$_GT___4136 clojure.core$_GT___4136@1d281f1>
02:09	hiredman	and fns have an implicit do
02:10	hiredman	,(do > (+ 1 2))
02:10	clojurebot	3
02:10	hiredman	,(do :foo 5 9 'c (+ 1 2))
02:10	clojurebot	3
02:10	Makoryu	, ((fn [] 'foo 'bar 'baz 'quux :IWouldLikeToOrderALargePizza 5))
02:10	clojurebot	5
02:11	mudphone`	Does that work with other foods?
02:11	mudphone`	:)
02:11	mudphone`	hiredman: thanks
02:11	Makoryu	mudphone`: Basically, you can put anything you want in between the [] and the 5, and it will be evaluated. If it doesn't have any side effects, it might as well not be there
02:11	mudphone`	Makoryu: thanks
02:12	Makoryu	And yeah, you can use other foods ;)
02:12	mudphone`	Interesting, so a function like > without arguments just returns true, in this case.
02:14	hiredman	eh?
02:14	hiredman	no
02:14	hiredman	not at all
02:14	mudphone`	ah, so it's not evaluating, it's a valid value, like you said
02:14	hiredman	it is evaluating, it's evaluating to the function object
02:15	hiredman	() is needed for calling the function
02:15	mudphone`	ah, ok
02:15	Makoryu	mudphone`: The function evaluates to itself. You have to call a function (eg. (>)) for it to be applied to any arguments (or zero arguments)
02:15	Makoryu	, >
02:15	clojurebot	#<core$_GT___4136 clojure.core$_GT___4136@1d281f1>
02:15	Makoryu	, 'pizza
02:15	clojurebot	pizza
02:16	Makoryu	, (>)
02:16	clojurebot	java.lang.IllegalArgumentException: Wrong number of args passed to: core$-GT-
02:16	Makoryu	,(> 5)
02:16	clojurebot	true
02:16	mudphone`	So, with the implicit do, the > is evaluated to itself, and then not used.
02:16	Makoryu	Yep
02:16	Makoryu	It's simply discarded.
02:17	mudphone`	ah ok
02:17	mudphone`	dare I ask why functions have the implicit do?
02:17	Chousuke	mudphone`: so that you can have more than one expression in them
02:18	Makoryu	mudphone`: Partly for the side effects, of course.
02:18	Makoryu	, (do (println "Sup") 5)
02:18	clojurebot	5
02:18	clojurebot	Sup
02:18	Chousuke	if they didn't have a do, you wouldn't be able to write (defn foo [] (print "debug") "result")
02:19	mudphone`	oh, so, hiredman meant the anonymous function's implicit do
02:19	mudphone`	I was thinking of the ">"
02:19	Chousuke	oh, and the > is not evaluated to itself! remember, it's a symbol :)
02:19	mudphone`	Chousuke: so > is evaluated to the function
02:20	Makoryu	mudphone`: People accustomed to certain other programming languages (which I will not name) would frown on this implicit do. However, Lisp has always had it even when it was called PROGN, and Clojure still has it now.
02:20	Chousuke	mudphone`: yeah. when evaluated, symbols are looked up to see if they name a var, then the var is dereferenced to get the actual value
02:20	Makoryu	(It used to serve the double purpose of allowing docstrings, but now we have the defn macro (and metadata) for that)
02:21	Makoryu	, pizza
02:21	clojurebot	java.lang.Exception: Unable to resolve symbol: pizza in this context
02:21	mudphone`	Chousuke: thanks, got it
02:21	mudphone`	Makoryu: is there a down-side to this implicit do?
02:22	Chousuke	mudphone`: not with functions :/
02:22	mudphone`	I'm assuming perhaps, the side effects?
02:22	hiredman	the implicit do doesn't make side effects, it only allows them if you put them there
02:23	mudphone`	hiredman: right, so is that why the implicit do is fowned upon? is my question
02:23	hiredman	uh
02:23	mudphone`	frowned upon
02:24	hiredman	what gave you that impression?
02:24	Makoryu	mudphone`: Not by Clojure programmers :p Ignore what I said earlier.
02:24	mudphone`	ah, ok
02:25	mudphone`	Chousuke: I didn't get your last comment.
02:26	Chousuke	Well, Clojure has fewer uses of implicit do/progn than common lisp. for example, cond expressions in CL have an implicit do
02:26	Chousuke	as a result, it needs an extra pair of parens for each expression :)
02:27	mudphone`	oh, ok, I see... I thought you were talking about vars
02:27	mudphone`	(and symbols)
02:33	Makoryu	Implicit do/PROGN is generally a good thing in Lisps like Common Lisp, which is much more procedural than functional
02:33	Makoryu	In Clojure, they're just redundant
02:49	tomoj	why is there no byte-array function?
02:52	Chousuke	there's into-array
03:33	mudphone`	Anyone know how to get something like (read-line) working from the Emacs Slime-REPL Clojure?
03:33	mudphone`	(read-line) as in getting user input?
03:36	Fossi	hi
03:48	megane	in gen-class, can i someway declare an array return type? when i try this: (ns testa (:gen-class :methods [[getA [int] int[]]])) , i get an inconvertible types error when i try to use that class from java. javac thinks getA's return type is int.
03:48	megane	using clojure 1.0
03:51	Chousuke	megane: of course, int[] is just the symbol int followed by an empty vector :)
03:51	Chousuke	megane: I think you want Integer/TYPE
03:51	Chousuke	wait, no... hmm
03:51	Chousuke	"[I" or something? :/
03:54	megane	:methods [[getA [int] "[I"]] ?
03:55	AWizzArd	~ max people
03:55	clojurebot	max people is 164
04:00	LauJensen	Good morning guys
04:00	arbscht	morning lau
04:01	licoresse	hello
04:02	Chousuke	megane: try it. I don't really know much about gen-class :/
04:03	megane	java.lang.ClassNotFoundException: java/lang/[I
04:04	Chousuke	hmmh
04:04	Chousuke	,(class (int-array))
04:04	clojurebot	java.lang.IllegalArgumentException: Wrong number of args passed to: core$int-array
04:04	Chousuke	,(class (int-array 1))
04:04	clojurebot	[I
04:04	megane	Integer[] gives similar results as int[]
04:04	Chousuke	yeah, the Integer[] is not the right syntax.
04:05	Chousuke	as I said, it's just a symbol followed by a vector :)
04:05	Chousuke	try "ints"?
04:07	megane	java.lang.ClassNotFoundException: java.lang.ints
04:07	Chousuke	hmm. maybe #=(Class/forName "[I")
04:08	Chousuke	(#= is read-time eval and that should return the class object for an integer array)
04:08	Chousuke	this really needs better syntax :/
04:09	megane	java.lang.ClassNotFoundException: Class
04:09	megane	:methods [[getA [int] #=(Class/forName "[I")]]
04:10	Chousuke	:(
04:23	megane	i got around it by using :methods [[getA [int] Object]] , returning (int-array ...) in getA, and at java side i casted the return value to int[]
04:41	pixelman_	mudphone`: use jline to get arrow up etc in the repl, here's my launch script http://followthedata.wordpress.com/2009/09/03/setting-up-clojure/
04:54	licoresse	.
04:59	vy	Is there a reader macro for writing bits? (E.g. As #b100101 in CL.)
05:05	Chousuke	hmm
05:05	Chousuke	,0b01010
05:05	clojurebot	Invalid number: 0b01010
05:05	Chousuke	there was some way to get an arbitrary radix...
05:05	Chousuke	,2r01010
05:05	clojurebot	10
05:13	lisppaste8	vy pasted "filter-by-bitmap" at http://paste.lisp.org/display/87426
05:13	vy	Chousuke: Thanks.
05:14	vy	Chousuke: Is that some Java reader notation?
05:14	vy	Can anybody help me to figure out why does filter-by-bitmap in http://paste.lisp.org/display/87426 returns ()?
05:18	vy	(Integer/reverse 2r110)
05:24	Chousuke	vy: what do you want it to do?
05:24	vy	Return items in coll by filtering agains turned on bits in the given number.
05:25	Chousuke	so 2r1010 would select items 0 and 2?
05:25	vy	Chousuke: Yup.
05:25	tomoj	I don't get it..
05:25	Chousuke	the bit-and with i is redundant
05:26	lisppaste8	vy annotated #87426 "filter-by-bitmap (via loop)" at http://paste.lisp.org/display/87426#1
05:26	Chousuke	:when (= 1 (bit-and 1 (bit-shift-right bits (- n i 1)))) works for me
05:27	vy	Oops! Silly me.
05:27	vy	What does "recur arg for primitive local: bits must be matching primitive" error mean?
05:28	vy	Hrm... It has some mapping problem too.
05:29	lisppaste8	vy annotated #87426 "filter-by-bitmap (via loop, fixed bit filtering)" at http://paste.lisp.org/display/87426#2
05:29	Chousuke	this sounds like an awfully compicated way of selecting items from a vector
05:30	vy	Chousuke: You mean "loop/recur" derivative instead of "for"?
05:30	Chousuke	both :P
05:30	vy	So what's your suggestion?
05:31	Chousuke	well, what are you doing this for? :/
05:32	vy	I'll filter the elements in a coll by looking at the turned on bits in a number.
05:33	Chousuke	it might be easier if you make a bit-pattern->lazy-seq function
05:36	lisppaste8	vy annotated #87426 "subsets" at http://paste.lisp.org/display/87426#3
05:41	Chousuke	hmm
05:49	vy	Chousuke: And guess what? It performs orders of magnitude better than existing clojure.contrib.combinatorics/subsets.
05:50	Chousuke	it depends on the count though :/
05:50	Chousuke	~def subsets
05:50	Chousuke	apparently so does that implementation. hm
05:51	tomoj	why are the elements wrapped in a vector?
05:55	tomoj	huh
05:56	tomoj	every once in a while c.c.combinatorics/subsets takes 10 times longer than usual
05:56	Chousuke	do you have escape analysis enabled?
05:56	tomoj	I don't even know what that means
05:57	Chousuke	I guess you don't then :P
05:57	Chousuke	it's a new JVM feature that IME seems to cause somewhat uneven performance behavious
05:57	Chousuke	behaviour*
05:58	lisppaste8	vy annotated #87426 "combinations" at http://paste.lisp.org/display/87426#4
06:01	vy	Chousuke: Moreover, while (clojure.contrib.combinatorics/subsets 21) throws some "GC foo bar limit exceeded error" (count (subsets (range 21))) returns in 799msecs.
06:03	tomoj	I don't think it's orders of magnitude better
07:13	somnium	is there any way to prevent the reader from choking on % outside of a string literal? :100% '100% ?
07:18	Fossi	what's the best way to join (take 2 "foo) back together?
07:18	Fossi	"foo"
07:26	xdp	hello
07:26	AWizzArd	Hi xdp
07:27	noidi_	,(apply str (take 2 "foo"))
07:27	clojurebot	"fo"
07:27	xdp	where is parallel.clj?
07:28	xdp	i want it to improve performance of my application
07:28	xdp	i'm using 1.1.0
07:29	xdp	ok, i found it in clj dir
07:30	xdp	what's diffs between clojure.core/pmap and parallel?
07:31	xdp	i'm now using pmap, i don't know if i should use parallel lib
07:32	xdp	any ideas?
07:35	cgrand	xdp: parallel.clj builds on the fork/join api, it should be smarter in how the load is distributed amongst cores
07:39	Fossi	yeah, we arrived at apply str as well, but deemed it unnecessary, so now we check the length
07:46	gerry_	parallel need jsr166y.jar support,right?
07:47	cgrand	gerry_: use the jsr166y.jar in the file section of the clojure group
07:47	rhickey	gerry_: yes, for clojure.parallel you can use the jar in the downloads section of the google group
07:48	rhickey	new work is going on in the par branch on github, in which case you should use the jar in the downloads section there
07:48	gerry_	oops, i have downloaded it from gee.cs.oswego.edu, but it seems not work
07:49	rhickey	that's a moving target
07:49	gerry_	ok,thx
07:49	rhickey	thus the downloads
07:49	rhickey	also the version on the google group will be the last to support JDK 1.5, they've stopped supporting it for ForkJoin
07:50	rhickey	so par moving forward will be Java 6+
07:50	gerry_	so, i have to wait?
07:51	rhickey	gerry_: wait for what?
07:51	gerry_	how about performance of clojure.core/pmap to parallel stuff?
07:51	gerry_	wait jsr166y.jar
07:51	rhickey	gerry_: pmap is unique in not needing the entire collection. OTOH, it is limited if your work-per-unit is small.
07:52	eevar2	speaking of the zip on google; where do I end up clicking 'download' on clojure.org, and then 'source'
07:52	rhickey	gerry_: you don't have to wait, just be aware that Java 5 is a dead end for jsr166y stuff
07:52	gerry_	ok
07:53	rhickey	and the libs are built on specific versions, since they are still changing the api
07:53	rhickey	i.e. the things that parallel are built on are not going to be in Java 7
07:53	gerry_	i have one gui application writen by swing, drawString in swing is too slow, i want to test parallel lib
07:53	rhickey	thus the par branch based directly on ForkJoin
07:54	gerry_	ok, i'll check it out
07:57	gerry_	i'm not sure whether swt is better for me
07:57	eevar2	gerry_: sure your performance issue isn't because of reflection?
07:58	eevar2	gerry_: i'd stay with swing
07:58	gerry_	no, mainly due to drawString methon
07:58	eevar2	gerry_: http://www.javaworld.com/javaworld/jw-05-2009/jw-05-clojure.html?page=5
07:58	gerry_	this method maybe slowest in swing lib :)
07:59	eevar2	add some type hints if you haven't already
08:00	eevar2	gerry_: more articles: http://www.google.no/search?hl=en&q=clojure%20type%20hints%20reflection%20-site:www.experts-exchange.com
08:00	gerry_	eevar2: i have done type hints
08:00	gerry_	thx for your link
08:12	gerry_	jsr166y.jar in google group works
08:12	eevar2	gerry_: what are you painting to?
08:13	eevar2	more likely to improve performance doing that, than paralellizing calls to drawString
08:13	gerry_	gogame board
08:13	gerry_	yes
08:13	eevar2	s/doing/switching to some other drawing surface
08:13	gerry_	i have to draw coords in board
08:14	gerry_	i haven't found any alternative methods to do that
08:15	gerry_	so i have to parallel them
08:31	gerry_	eevar2: just like this: http://imagebin.ca/view/oIsKZUe6.html
08:33	eevar2	how many times do you call drawString?
08:34	gerry_	about 40times
08:35	eevar2	and that's a bottleneck, you think?
08:35	gerry_	and 360 time repaint
08:35	gerry_	s/time/times
08:36	gerry_	dont' much slow, really a bit slow, but i want perfect :)
08:39	gerry_	enable drawSting, i got about 1 second stalling compare with disable drawsting
08:39	gerry_	s/drawSting/drawString
08:42	gerry_	i'm using agent to repaint
08:43	gerry_	i don't know whether this is thread safe
08:50	gerry_	(map f (par cloll)) just work?
08:50	gerry_	or (pmap f (par coll))?
08:52	Chouser	I'm not sure, but I would guess 'par' is a linear (single-threaded) process
08:53	Chouser	so it might be better to do (par coll) earlier and then keep the result around and reuse it.
08:55	gerry_	(par coll :map f)?
08:55	Chouser	I think that would also be a non-parallel process.
08:55	gerry_	Chouser: (let [pcoll (par coll)] (map f pcoll)) like this?
08:55	Chouser	pmap, but yes.
08:56	gerry_	ok
08:56	Chouser	well, assuming you do other things in that 'let' as well.
08:57	Chouser	if all you do in the 'let' is run 'pmap' once, you might as well use your original statement.
08:57	gerry_	s/map/pmap will be better?
08:58	Chouser	wait, this is wrong. hand ong.
08:58	gerry_	oh?
08:58	Chouser	sorry, 'pmap' doesn't require the use of clojure.parallel at all
08:58	Chouser	(doc pmap)
08:58	clojurebot	"([f coll] [f coll & colls]); Like map, except f is applied in parallel. Semi-lazy in that the parallel computation stays ahead of the consumption, but doesn't realize the entire result unless required. Only useful for computationally intensive functions where the time of f dominates the coordination overhead."
08:59	Chouser	pmap works on regular sequences, you don't need a "parallel array" first.
08:59	gerry_	but if i use it with par?
09:00	gerry_	what will happen?
09:00	Chouser	I should probably stop talking about clojure.parallel, because I just don't know it that well.
09:00	Chouser	anyone else have some advice?
09:01	gerry_	ok, let me try it
09:02	eevar2	gerry_: i'd say your rendering code/approach is broken somewhere. try running a profiler or something. or reading the swing docs
09:05	gerry_	eevar2: i have figured it out by disable drawString and enable it
09:05	gerry_	problem is there,i'm sure
09:06	eevar2	okies. i have nothing further to contribute. good luck
09:07	gerry_	thx anyways
09:07	gerry_	Chouser, map seems better than pmap in this case
09:08	Chouser	wait, you're running swing drawing methods in multiple threads? I don't think this is supported.
09:09	Chouser	swing wants pretty much all drawing to happen from its event thread.
09:10	gerry_	Chouser, i just repaint in agent thread, and it works
09:10	gerry_	but not in event thread
09:12	gerry_	and sound play also in agent thread
09:15	gerry_	oh,yes, repaint still call back to original thread
09:25	gerry_	maybe problem due to videocard support in opensolaris? i'll try it on windows or linux
09:26	gerry_	ati support in opensolaris sucks
09:31	gerry_	ok, time to go
09:31	gerry_	thx, bye
09:35	Jomyoot	Can Java.util.HashMap readily be converted into Clojure Hash?
09:35	Jomyoot	like { :a 1 :b 2 :c 3 }
09:35	Chouser	(into {} my-hash-map)
09:35	Jomyoot	hmm
09:35	Chouser	,(into {} (java.util.HashMap. {:a 1, :b 2, :c 3}))
09:35	clojurebot	{:a 1, :b 2, :c 3}
09:36	Jomyoot	so from Java :a is actually "a" right?
09:36	Chouser	That's a Clojure PersistentHashMap to java HashMap and back.
09:36	AWizzArd	no
09:36	Chouser	Java HashMap can store Clojure keywords
09:37	AWizzArd	they are ordinary objects, like you and me
09:37	Chousuke	,({:a 1 "key" 2} "key")
09:37	clojurebot	2
09:37	eevar2	,(:a (java.util.HashMap. {:a 1 :b 2 :c 3}))
09:37	clojurebot	1
09:37	Chouser	if you have a Java HashMap with string keys and you want a clojure PHM with keyword keys, I'd look at zipmap
09:38	Jomyoot	hmm
09:38	Chouser	,(let [jhm (java.util.HashMap. {"a" 1, "b" 2, "c" 3})] (zipmap (map keyword (keys jhm)) (vals jhm)))
09:38	clojurebot	{:a 1, :c 3, :b 2}
09:40	Jomyoot	is that a natural way to do it?
09:40	Jomyoot	or is that considered a hack?
09:40	Jomyoot	If I like to pass Clojure hash back and forth with Java program
09:40	Chousuke	why would you change the keys at all?
09:40	Chousuke	just let them be as they are
09:40	Chouser	Jomyoot: any reason not to leave the keys as strings?
09:40	eevar2	just use string keys
09:41	Jomyoot	ok then
09:41	Chouser	:-)
09:41	AWizzArd	maybe you don't even need to convert it into a persistent map at all?
09:41	Chouser	slightly less pretty in the Clojure code, but less mucking around too.
09:41	AWizzArd	clojures function (get ...) works on j.u.Map's as well
09:44	avital	hi. is there any way to use for to collect more than one element on each iteration? something like (for [x [1 2 3]] x (+ x 10)) that would return '(1 11 2 12 3 13)
09:45	AWizzArd	you could collect [x (+ x 10)] and get ([1 11] [2 12] [3 14])
09:46	avital	yes i could also do (union (for [x [1 2 3]] [x (+ x 1)]))
09:46	avital	but that seems weird
09:46	avital	,(union (for [x [1 2 3]] [x (+ x 1)]))
09:46	clojurebot	java.lang.Exception: Unable to resolve symbol: union in this context
09:46	avital	,(set/union (for [x [1 2 3]] [x (+ x 1)]))
09:46	clojurebot	java.lang.Exception: No such namespace: set
09:46	avital	,(clojure.set/union (for [x [1 2 3]] [x (+ x 1)]))
09:46	clojurebot	([1 2] [2 3] [3 4])
09:46	avital	,(clojure.set/union (for [x [1 2 3]] [x (+ x 10)]))
09:46	clojurebot	([1 11] [2 12] [3 13])
09:47	AWizzArd	,(apply concat (for [x [1 2 3]] [x (+ x 10)]))
09:47	clojurebot	(1 11 2 12 3 13)
09:47	AWizzArd	otherwise, there is always (loop ...)
09:47	avital	ok nice that works but it's too hacky, shouldn't for support multiple values added per iteration or something of the sort?
09:48	Chouser	,(let [v [1 2 3]] (interleave v (map #(+ 10 %) v)))
09:48	clojurebot	(1 11 2 12 3 13)
09:48	AWizzArd	avital: could be useful. In functional programming it is a design pattern to write your own map/filter/etc functions that can do what you need in one go
09:48	AWizzArd	if you want to traverse the list only once then loop is a good start to implement such a function
09:48	avital	Chouser chouser chouser chouser the apply suggestion also works and is much more readable. I am asking why this would not be part of for
09:49	avital	AWizzArd: ok we'll implement our for that supports this
09:49	Chouser	avital: :-) beauty is in the eye of the beholder
09:50	AWizzArd	avital: the most typical use case is what for currently supports. I agree that it would not be bad to have something in place that works for inserting multiple values, but I guess it is a bit too special.
09:50	Chouser	avital: I've used (apply concat (for ...)) a few times. Many of those times I eventually found that there was a better way in the large.
09:50	Chouser	avital: why do you want interleaved values like that? I mean, what consumes that seq?
09:50	avital	the specific example
09:50	avital	we are writing a google wave robot
09:50	AWizzArd	oh good
09:50	avital	we need to send operations to be done on several waves
09:51	avital	each operation is actually two operations in one - a delete and an append operation (instead of one replace operation)
09:51	avital	so we collect all the wave ids that we need to act on in a list
09:51	avital	and then create the json response containing the delete and append operations
09:51	avital	each wave id needs to generate _two_ operations
09:51	avital	in a nice interleaved way
09:51	Chouser	avital: it's important that they happen interleaved, and not all appends followed by all deletes?
09:52	AWizzArd	avital: which lib do you use to parse/compose json?
09:52	avital	Chouser: Maybe not but even so such a case might happen, it should be a solvable problem even if in this case it's not necessary
09:52	Chouser	,(mapcat #(list % (+ 10 %)) [1 2 3 4])
09:52	clojurebot	(1 11 2 12 3 13 4 14)
09:53	avital	AWizzArd: clojure.contrib.json
09:53	AWizzArd	oki good, i also want to begin to use it right now
09:53	avital	AWizzArd: For wave?
09:54	Chouser	avital: of course it's solvable. The question is whether adding more complexity to 'for' is worth the benefit. If the use cases are largely theoretical, one may being to doubt the value.
09:54	avital	Chouser: What?! As far as I see the world, if you lose nothing and gain something it's always a good idea. No?
09:54	Chouser	adding complexity to 'for' is losing some simplicity
09:54	avital	Sorry for the What?! I meant What?
09:55	Chouser	not that there's much simplicity left in 'for' to lose! :-)
09:55	avital	Chouser: No loss of simplicity. If someone doesn't want to know about the posibility of putting several values they don't need to even know that exists
09:56	Chousuke	avital: what if someone wants a side-effect in for... for debugging? :)
09:57	avital	Chousuke: not sure what you mean...
09:57	Chousuke	(for [x someseq] (println "X: " x) x)
09:58	avital	Chousuke: So you're saying that you think what I'm suggesting is a good idea? again not sure...
09:58	Chousuke	with your multi-expression extension, you'd get a seq of (nil a nil b nil c...) :/
09:58	avital	No
09:58	avital	If you want to do that you'd do
09:58	avital	,(for [x [1 2 3] (do (println "X: " x) x))
09:58	clojurebot	Unmatched delimiter: )
09:58	avital	,(for [x [1 2 3] (do (println "X: " x) x)
09:58	clojurebot	EOF while reading
09:58	avital	,(for [x [1 2 3]] (do (println "X: " x) x)
09:58	clojurebot	EOF while reading
09:58	avital	,(for [x [1 2 3]] (do (println "X: " x) x))
09:58	Chouser	'for' doesn't support more than one body expression now anyway. no implicit 'do'
09:58	clojurebot	(1 2 3)
09:59	Chousuke	oh, hmm :/
09:59	Chouser	,(for [x [1 2 3]] x (+ x 10))
09:59	clojurebot	java.lang.IllegalArgumentException: Wrong number of args passed to: core$for
09:59	avital	Chousuke: I'm suggesting to allow for multiple values in the body expression in a for. If you want to do your thing, just use (do ...)
09:59	Chouser	not sure how chunking should work with multiple values.
10:00	Chouser	just generate bigger chunks I suppose?
10:00	avital	what is chunking sorry?
10:00	Chousuke	avital: hm. that might be fine
10:00	Chousuke	avital: but I'll leave the implementation to you
10:00	Chousuke	~def for
10:00	Chouser	avital: welcome to the complexity that is 'for'
10:00	Chousuke	good luck :P
10:00	avital	Sure, ayal is implementing for1 as we speak
10:00	avital	forx
10:01	rhickey	if 'for' did that, wouldn't people want the same from map (somehow?), it's a general problem of expansive mapping
10:02	avital	I'm relatively new to Clojure and FP but in the meanwhile I've gotten to the point that I almost always prefer to use for than map/filter/etc unless I have a pre-existing function or predicate that just perfectly works.
10:02	Chouser	they would certainly want the same from 'doseq', but 'doseq' already provides the analogue
10:02	rhickey	certainly putting multiple values after one another like that is a mismatch with blocks elsewhere
10:02	Chousuke	I guess internally multi-value-for would have to be quite similar to (apply concat (for ...)) anyway :/
10:02	rhickey	forcat a la mapcat?
10:02	avital	rhickey: Sorry, not sure what you mean...
10:02	Chouser	for is already a bit like mapcat
10:02	AWizzArd	avital: not for wave, for some other server side app i want json
10:03	jdz	when do we have a lolcat?
10:03	AWizzArd	what was this again?
10:03	Chousuke	"applies a funny operation to the input. produces a list, if input is cheezburger"
10:04	avital	It's not easy to add this to map since map takes a function anyways
10:04	avital	But it seems natural to add it to for
10:04	jdz	*produces a very lazy list :)
10:06	avital	As far as I understand, for is the generic wrapper for a bunch of stuff that could've been done with combinations of map filter and much more
10:06	avital	but in general at some point of complexity (like where we are) the solutions with map/filter are too crazy and for renders a natural and simple implementation
10:07	avital	so since for anyways is a huge machine that eases use of map/filter/etc why not give it as much functionality as possible?
10:07	AWizzArd	avital: well, reduce is the generalization of map/filter
10:07	Chouser	avital: because that way lies madness (a.k.a. Common Lisp's LOOP)
10:08	avital	AWizzArd: no, reduce map and filter work together and they are orthogonal in functionality
10:08	Chousuke	avital: except you can implement both map and filter with reduce :/
10:08	AWizzArd	what can map/filter do what reduce can't?
10:08	Chousuke	avital: albeit not lazily :)
10:08	manic12	does anybody else have a problem with swing crashing the netbeans repl?
10:09	avital	Chousuke: Ah, yes I see now; but I see that as a hack. In my view the most important aspect of code is its readability. map/filter are more readable than the equivalent weird reduce that would implement them
10:09	AWizzArd	yes
10:09	avital	It's all about keeping the code as similar as possible to a human language as possible
10:09	avital	for looks like a human language
10:09	AWizzArd	sure
10:10	avital	And in a human language I'd like to be able to say "go over all these elements and for each one collect two elements"
10:10	AWizzArd	but for example a composition of filter and map may better be expressed with one reduce, which can do the work in one go
10:10	avital	instead of collecting lists and then apply concat'ing them
10:10	AWizzArd	avital: write a useful collect macro and open source it :p
10:11	jdz	what's the for incantation to go over a sequence with a counter?
10:11	avital	AWizzArd: My colleage Ayal is writing it as we speak.
10:12	Chousuke	I'm not really opposed to the idea itself but I think for supporting multiple expressions is somewhat... unexpected :/
10:14	jdz	i'd like to see CL's iterate in clojure, but...
10:14	jdz	not enough to go and start writing one, apparently
10:14	Chousuke	I think it would be conceptually simpler to have for be a "simple" list comprehension.
10:15	AWizzArd	jdz: want it for compatibility / code reuse?
10:15	clojurebot	for is not a loop
10:16	hiredman	~suddenly
10:16	clojurebot	CLABANGO!
10:16	AWizzArd	cemerick: new record!
10:16	AWizzArd	~ max people
10:16	clojurebot	max people is 165
10:16	jdz	AWizzArd: not really. just for not writing complicated loop/recurs
10:17	AWizzArd	thesnowdog_: grats, you made the new record
10:17	cemerick	AWizzArd: man, no one even knows what you're talking about! ;-)
10:17	AWizzArd	cemerick: the max people thingy
10:17	AWizzArd	it was set in February I guess
10:17	cemerick	oh, I know what you're talking about
10:17	AWizzArd	great :)
10:18	lisppaste8	Chouser pasted "support multiple values in 'for' body" at http://paste.lisp.org/display/87441
10:19	Chouser	not so hard to do, which concentrates us on the question: is it good to have?
10:19	hiredman	it's 7am, I don't need to see that
10:19	Chouser	note that doesn't do each value lazily, which could be desirable.
10:21	AWizzArd	hi ayal
10:22	lisppaste8	ayal pasted "forex macro" at http://paste.lisp.org/display/87442
10:22	ayal	AWizzArd: hi!
10:24	cgrand	stupid question: why for isn't implemented in terms of mapcat/map/filter? for perf reasons (easier on allocations)?
10:24	Chouser	hm. ayal's is simpler. :-)
10:24	ayal	Chouser: Thank you.
10:25	Chouser	cgrand: I actually looked into doing that at some point. I forget why I gave up...
10:25	Chouser	maybe just that some features are very hard to implement that way too. Such as :while.
10:26	AWizzArd	~seen kotarak
10:26	Chouser	though thinking about it again now, I don't know why a take-while with a special value wouldn't work.
10:26	clojurebot	no, I have not seen kotarak
10:26	cgrand	isn't :while a take-while?
10:27	Chouser	I looked at it when adding chunk support, because it would have been much nicer to just build on the chunk support already in map/filter
10:28	Chouser	maybe it was just performance. should have made some notes. :-/
10:54	ben_m	Hi there :) This line: `javax.swing
10:54	ben_m	gah.
10:54	ben_m	Copy-paste fail.
10:55	ben_m	(for [x (range 10)] (.add (. (new JLabel) (setPreferredSize 10 10))))
10:55	ben_m	I get an error: "Wrong number of args passed to: core$for (grid.clj:5)
10:56	ben_m	(I'm aware that the code might have more errors except the for one, I'm new to both Java and Clojure :)
10:56	Chouser	I get: No matching method found: setPreferredSize for class javax.swing.JLabel
10:57	Chouser	note you're mixing method call style there.
10:57	ben_m	I'm in a (doto frame ...)
10:58	ben_m	If that helps at all :)
10:58	Chouser	oh!!
10:58	Chouser	yeah
10:58	Chouser	that changes everything. :-)
10:58	ben_m	I'm tring to create 10 Labels inside the frame
10:58	Chouser	the doto will be inserting something after the first word of the list
10:58	ben_m	There's probably a better way instead of using for and range, but I don't know it :)
10:58	Chouser	(for <thing here> [x (range 10)] ...)
10:58	ben_m	Ah!
10:59	Chouser	you've outgrown that particular 'doto'. Time to put the object in a local (using 'let') and then try your loop again.
10:59	Chouser	this time use 'doseq' instead of 'for' because you're looping for side effects.
11:00	hiredman	I think the reason I don't use for often (almost never) is it's lack of composability
11:01	lisppaste8	gluckspilz pasted "untitled" at http://paste.lisp.org/display/87445
11:01	hiredman	how do you use for inside a ->
11:01	Chousuke	you overuse -> anyway :P
11:02	Chouser	wait, how do you use 'map' inside a -> ?
11:02	hiredman	((partial map fn))
11:03	Chousuke	that automatically looks ugly to me because of the double parens ;/
11:03	hiredman	you get used to it
11:04	Chousuke	more likely I will just write it some other way
11:17	tmountain	anybody know if clojure has a builtin to test if a number falls within a given range ?
11:17	Chouser	,(< 2 5 10)
11:17	clojurebot	true
11:18	tmountain	whoa, wasn't aware of the three argument version
11:18	tmountain	thanks
11:19	Chouser	sure. don't know of any that is like a <= b < c, which I've wanted once or twice.
11:20	ben_m	,paste
11:20	clojurebot	java.lang.Exception: Unable to resolve symbol: paste in this context
11:20	ben_m	!paste
11:20	ben_m	Hm.
11:20	Chouser	~paste
11:20	clojurebot	lisppaste8, url
11:20	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
11:20	ben_m	Oh ;)
11:23	lisppaste8	ben_m pasted "Clojure & Swing problem" at http://paste.lisp.org/display/87447
11:23	ben_m	If anyone could take a look at that ... error etc. is at the bottom of the paste
11:23	ambient	btw, does clojure have clear distinction between mutation and immutable? http://blog.plt-scheme.org/2009/09/set-vs-set-box-and-unbox.html
11:24	ambient	i wonder how syntax highlighting would work for that
11:25	Chouser	ben_m: I get Unable to resolve symbol: x in this context, because the doseq is closed after the println
11:25	Chouser	ambient: there's no perfectly reliable visual indicator, if that's what you mean.
11:26	ben_m	Chouser: Oh sorry. I added that println for debugging purposes, it's not usually.
11:26	Jomyoot	is there a way to concat results of doseq like mapcat?
11:26	Chouser	ambient: functions that mutate tend to end with !, access to mutable things use either . interop or @, generally.
11:26	ambient	Chouser only truly mutable thing in clojure i've found is arrays :p
11:26	Chouser	Jomyoot: doseq has not results
11:27	Chouser	ambient: all the reference types are mutable: atom, ref, var, etc.
11:27	Jomyoot	i guess i use mapcat then
11:27	ambient	Chouser as far as i've understood them, they're all atomic
11:27	Chouser	well, protected yes, but still mutable
11:27	ambient	true
11:28	ambient	perhaps i should've formulated my question better
11:29	Chouser	ben_m: .. returns the final thing, in your case the return value of setPreferredSize. Adding that value to 'frame' is what's failing.
11:29	ben_m	I feared it was something like that
11:30	Chouser	ben_m: using 'doto' in there, or storing the fram in a local will clear that up.
11:31	ben_m	How would I use doto?
11:32	Chouser	(.add frame (doto (new JLabel (str x)) (.setPreferredSize (new Dimension 10 10))))
11:34	ben_m	Awesome :)
11:34	ben_m	Thank you.
11:37	tmountain	is there an easy way to see if a sequence contains a given set of values?
11:38	Chouser	a set? like in order, or all of them in any order, or ?
11:38	tmountain	basically just want to see if a sequence contains all values provided
11:39	tmountain	so if the sequence contained 1, 2, 3, 4, 5 and I provided 2 and 4, it would be true. 2 and 6 would be false
11:40	tmountain	I could do it with some loop logic, but I'm guessing there's probably a better way
11:40	Chouser	tmountain: it's best to use a set instead of a seq if you're mainly going to be doing contains tests.
11:40	Chouser	either way, you might like 'every?'
11:41	Chousuke	,(every? boolean (map (set [1 2 3 4 5 6]) [2 4]))
11:41	clojurebot	true
11:41	Chouser	,(every? #(.contains '(1 2 3 4 5) %) [2 6])
11:41	clojurebot	false
11:41	tmountain	oh, that's great
11:41	tmountain	thanks for all the help this morning
11:41	tmountain	playing around with a yahtzee implementation in clojure ;-)
12:04	Jomyoot	how would I iterate over a [vector] with index i and concat all results?
12:04	clojurebot	with style and grace
12:05	Jomyoot	well yeah
12:06	stuartsierra	,(map (fn [x i] (prn x i)) [:a :b :c] (iterate inc 0))
12:06	clojurebot	(nil nil nil)
12:07	stuartsierra	,(map (fn [x i] [x i]) [:a :b :c] (iterate inc 0))
12:07	clojurebot	([:a 0] [:b 1] [:c 2])
12:08	Chouser	which is what seq-utils/indexed does, I believe
12:12	stuartsierra	yep
12:41	technomancy	I'm thinking of adding more elements to the warning-face in clojure-mode. seems like set! should be in there; any other suggestions?
12:42	technomancy	io! is already there
12:44	hiredman	aset*
12:44	hiredman	?
12:45	technomancy	sounds good
12:58	cgrand	technomancy: symbols starting with &
12:58	technomancy	cgrand: I don't even know what those mean. =)
12:58	technomancy	care to explain?
13:01	cgrand	I repeatedly saw newcomers to forget the space between & and the symbol in destructuring forms
13:01	hiredman	[a & b] vs [a &b]
13:02	technomancy	oh, to catch mistakes; I see
13:02	technomancy	or people forgetting clojure is not CL. =)
13:03	hiredman	clojurebot: is this allegro?
13:03	clojurebot	this is not allegro
13:37	lisppaste8	ben_m pasted "Problem & Question of style" at http://paste.lisp.org/display/87454
13:38	ben_m	^-- If anyone could tell me if some things are not idiomatic or some things are better done in another way
13:38	ben_m	Also, at the commented two lines, some of the JLabels are supposed to have a blue background, but they don't :D
13:39	manic12	if I create a swing JFrame in clojure started from a command prompt, it works. if I create a JFrame in enclojure repl it gives a stack buffer overrun as it crashes
13:41	manic12	seeing as how I have to start and stop the enclojure repl just to recompile a gen-class, I think this may be a good reason to switch to something else besides netbeans
13:42	manic12	is emacs/slime/clojure the most supported setup?
13:57	Licenser__	you will like to hear that but I hate threads and locking grrrr
13:58	ben_m	Are you using Clojure?
13:59	Chouser	re-compiling and then using a genclass always requires restarting a JVM.
13:59	samhughes	hey there. calling (def #^{:private true} myname "samuel") keeps the variable only accessible to its namespace, but that's not the for refs, e.g., (def #^{:private true} myname (ref "samuel")). is there a reason for that?
14:00	Licenser__	ben_m: no that is the problem :P
14:00	Licenser__	I just wanted to use my frustration to cheer you people up
14:01	ben_m	Licenser__: Thank you kindly.
14:01	Licenser__	you are welcome ben_m, at lest someone can have a gain from this $§!&! code
14:05	hiredman	I was just using some ruby xmpp bot library to monitor and control builds, that was a nightmare with regards to threading
14:06	hiredman	I really should just throw it all out and do it in clojure
14:07	samhughes	speaking of nightmare, (def #^{:private true} myname (ref "samuel")) not actually making myname private is a nightmare.
14:08	hiredman	samhughes: does here
14:08	Licenser__	hiredman: I know ...
14:08	hiredman	samhughes: what version of clojure is this?
14:08	Licenser__	but I've a ruby library that does not exist in clojure
14:08	hiredman	do you have a test case?
14:09	hiredman	~paste
14:09	clojurebot	lisppaste8, url
14:09	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
14:09	samhughes	i think it's 1.0.0
14:11	samhughes	sure, one sec (on the paste)
14:14	lisppaste8	samhughes pasted "private refs" at http://paste.lisp.org/display/87456
14:18	Chouser	both give an exception for me, in both 1.0.0 and latest master
14:19	hiredman	same here
14:19	hiredman	I just grabbed the 1.0 zip and this works as expected
14:20	samhughes	you're right, with that test, it did. one sec. i'm going to retrace the sceneario and paste it.
14:21	hiredman	I would suspect some sort of pollution, i.e. repl that has been running for a while and you having imports and uses and requires all over the place
14:23	lisppaste8	samhughes pasted "second try at refs" at http://paste.lisp.org/display/87457
14:24	Chouser	heh. don't do that.
14:25	samhughes	which part? i wouldnt normally have both namespaces in one file if thats what you mean.
14:25	Chouser	no, don't call 'def' from somewhere other than top level.
14:26	hiredman	def is a global scope thing
14:26	hiredman	and beyond that, def gets it's namespace stuff setup at compile time
14:26	hiredman	so the namespace a thing is def'ed in is what namespace the form is in at compile time
14:27	samhughes	yeah. i just wanted a way to define it from another namespace but still keep it private. but i could use ref-set within the function, and define outside, i assume?
14:27	hiredman	in summary, don't do that
14:27	samhughes	referring to the last thing i just said?
14:27	Chousuke	you can do ref-set in the setup-ref function
14:27	hiredman	no
14:27	Chousuke	that's the proper way
14:28	hiredman	are you sure you need the ref?
14:29	samhughes	not necessarily. i'm creating api for memcached, and want to keep my sockets alive. but it doesn't necessarily need to be a ref.
14:29	hiredman	:(
14:29	Chouser	on the other hand, what the heck is actually happening there?
14:30	hiredman	it shouldn't be a ref
14:30	hiredman	definitely
14:30	hiredman	refs/atoms/agents are for holding immutable objects
14:30	Chouser	(meta #'my-ref) => {:ns #<Namespace names>, :name my-ref, :file "NO_SOURCE_PATH", :line 4, :private true}
14:30	hiredman	(that apear to change)
14:30	Chouser	that all looks right, so why is the privacy check failing?
14:31	samhughes	but my thinking was that additional sockets might be appended by multiple threads, so i'd want that happening in sync.
14:31	Chousuke	maybe because it's the same compilation unit? :/
14:31	Chousuke	samhughes: so you still want to have a global socket pool?
14:32	Chousuke	in that case, a ref is fine.
14:32	hiredman	Chousuke: it doesn't fail here
14:33	samhughes	Chousuke: yeah, i think so. i'm guessing that i'll have multiple servers handling the pool.
14:34	hiredman	samhughes: is there a reason to have the api keep track of the sockets, instead of having the user call an api method to create a socket, then pass it around, either via binding or explicitly
14:34	hiredman	ugh
14:34	hiredman	Chouser: the privacy check doesn;t fail here
14:35	hiredman	(use 'names) in the example does fail
14:35	Chouser	well, it really does here.
14:35	Chouser	yeah, I used (refer 'names)
14:35	hiredman	hoho
14:35	hiredman	interesting
14:35	Chouser	before calling setup-ref: (meta #'names/my-ref) => {:ns #<Namespace names>, :name my-ref}
14:36	hiredman	java.lang.Exception: Unable to resolve symbol: my-ref in this context
14:36	Chouser	the var is there with some metadata, but unbound.
14:36	hiredman	(after refer 'names)
14:36	Chouser	right
14:36	Chouser	oh
14:36	hiredman	nice
14:36	Chouser	which is all what I would expect
14:37	Chouser	then after calling setup-ref, names/my-ref has the private flag and is bound. This surprised me -- I expected it to create a var in the testcase namespace
14:37	samhughes	hiredman: i'm still debating on the best route. but you're right, it may be better to keep them on the client side, adn have them passed in.
14:39	samhughes	yeah, because each server will have its own set of sockets.
15:36	drewr	is there a version of future with a timeout?
15:38	Chouser	drewr: it's been asked for
15:38	drewr	ah, ok
15:38	Chouser	drewr: actually, I have a unhappy implementation I'm using right now
15:39	Chouser	you call the promise rather than deref'ing it, so you can provide the timeout as an arg. :-/
15:41	hiredman	time out on the deref, or time out on what the future is doing?
15:42	Chouser	oh, mine is promise/deliver, not future. sorry.
15:42	tomoj	I thought I remembered hearing something about how derefs automatically call functions.. seems they don't. is there something like that somewhere that I'm confusing this with?
15:42	Chouser	tomoj: calling a var calls its value
15:42	hiredman	.get on the future object takes a timeout unit
15:43	tomoj	Chouser: sure, like (@foo) ?
15:43	tomoj	but I thought there was some special thing somewhere (maybe not with deref) where a function would automatically be called
15:43	sfuentes	so i'm new to clojure and i'm trying to learn the language by implementing a few data structures. i understand that clojure may already have sufficient data structures but this is again more of a learning exercise. anyway, i'm trying to implement a basic queue. the create-queue and dequeue functions are simple enough. however i'm stuck on writing an enqueue function.
15:44	Chouser	tomoj: well, (#'foo) is like (@#'foo) or (foo) -- maybe that's not what you were thinking of though.
15:44	sfuentes	now i don't want to traverse the whole queue to simply enqueue an item
15:44	tomoj	Chouser: exactly!
15:44	hiredman	sfuentes: see pop and peek
15:46	tomoj	(foo) == (@foo), that's what I was thinking of
15:47	sfuentes	hiredman: well i guess i'm trying to implement peek/last
15:47	sfuentes	but in O(1)
15:48	sfuentes	i think last is O(n)
15:48	tomoj	what's your underlying data structure?
15:48	tomoj	a list?
15:48	Chouser	tomoj: that's not true for all reference types
15:48	sfuentes	yes
15:48	Chouser	tomoj: appears to work for vars and refs
15:48	tomoj	so.. just store the queue in reverse order, like peek/pop/conj
15:49	tomoj	then enqueue/dequeue is O(1)
15:49	Chouser	you can't do O(1) queue and deque on a list
15:49	tomoj	sure you can..
15:50	Chouser	not a persistent list
15:50	tomoj	oh
15:50	tomoj	I'm thinking cons cells I suppose
15:50	tomoj	pop isn't linear, though, is it?
15:50	tomoj	(nor conj?)
15:50	sfuentes	items in a list can be referenced by index, no?
15:51	Chouser	sfuentes: sure, O(n) though
15:51	sfuentes	what? indexing is O(n)?
15:51	Chouser	clojure.lang.PersistentQueue is built on a clever combination of a vector and a list.
15:52	Chouser	sfuentes: yes! a list is essentially a linked list. traversal is O(n)
15:52	tomoj	is the reason pop isn't O(1) similar to the reason hash access isn't O(1)?
15:52	Chouser	sfuentes: vectors are indexed
15:52	tomoj	I haven't looked into the implementation of persistentlist
15:53	Chouser	list and vector both provide O(1) (or nearly) push and pop for stack-like access.
15:53	sfuentes	ok so i guess i should be implementing my queue using vectors
15:53	sfuentes	what's the downside of that i wonder
15:54	Chouser	if vectors or lists could provide effiecient queue-like behaviour, they would already.
15:55	tomoj	ooh, slaps self
15:55	tomoj	I was thinking of a stack, not a queue
15:55	Chouser	ah. yes, both list and vector can do fast push (called conj) and pop.
15:56	Chouser	for a list it's essentially the same as conj/rest. for a vector, pop is special.
15:58	Chouser	finger trees provide fast consLeft/rest on the left and fast conjRight/pop on the rigth, so can be used as stack or queue going either direction.
15:59	sfuentes	I'm sorry, I was rudely disconnected so I might have missed a few things. Anyway, so if I want to implement a queue I should be using a vector, right? if so, are there any downsides?
15:59	Chouser	sfuentes: if vectors or lists could provide effiecient queue-like behaviour, they would already.
16:00	sfuentes	it seems like state would help here
16:00	sfuentes	but i'd hate to be accused of heresy.
16:00	hiredman	how would it help?
16:01	Chouser	you can conj onto the right end of a vector fast, and traverse from the left fast (using first/next), but 'next' would return a seq not a vector, so conj on the right would no longer be fast.
16:01	Chouser	you could build a mutable queue out of a doubly-linked list of 3-element arrays or something. :-(
16:02	tomoj	PersistentQueue is not a finger tree, is it?
16:02	sfuentes	i retract my comment. is there such a thing as pointers or pointer-like things in clojure?
16:02	Chouser	tomoj: no, it's a clever combination of a vector and a seq
16:02	hiredman	I think the pqueue constructor takes a seq a vector and a map
16:03	Chouser	sfuentes: building fast persistent data structures is hard, with the exception of the singly-linked list.
16:04	tomoj	but worth it :)
16:05	Chouser	but PersistentQueue isn't too complicated, I guess. Might be interesting to try writing it in Clojure.
16:05	Chouser	will have to be done eventually. :-)
16:07	hamza	hey guys, i am trying to create xml, been playing ith prxml, can i use to create a string instead of printing to out?
16:07	hiredman	,(doc with-out-str)
16:07	clojurebot	"([& body]); Evaluates exprs in a context in which out is bound to a fresh StringWriter. Returns the string created by any nested printing calls."
16:08	sfuentes	Chouser: so implementing an efficient queue in clojure is more difficult/complex than in a language like C?
16:09	Chouser	no
16:09	hamza	thx is this the recommended way of doing this or is there a lib that i am not aware of?
16:09	Chouser	implementing an efficient persistent queue is more difficult/complex than a mutable queue
16:10	sfuentes	persistant is efficient in this context, correct?
16:11	Chouser	Yeah, I guess I should have said efficient immutable.
16:11	Chouser	so pick a goal -- immutable queue or mutable queue.
16:11	vy	Is anybody able to succeed running (count (clojure.contrib.combinatorics/subsets (range 20))) without getting an OOM exception?
16:12	Chouser	if you want to try doing an immutable one, I'd recommend learning about an efficient data structure that someone else has already figured out -- Clojure's PersistentQueue, 2-3 finger trees, or something else.
16:14	Chouser	actually, creating and using a persistent collection would be much more difficult in C because of no GC.
16:15	sfuentes	couple questions here
16:15	sfuentes	why would i want an immutable vs a mutable queue?
16:18	Chouser	immutable collections are much easier to use safely -- no iterator errors when they change while iterating, no chance some fn you call will delete data you need, no concurrency issues at all.
16:18	hiredman	equal immutable things are always equal
16:18	Chouser	they're very nice, and having good immutable collection and a standard API that supports using them comfortably is a huge part of what makes Clojure good.
16:20	sfuentes	i see. but mutable queues are more efficient, correct?
16:21	Chouser	they can probably be made slightly faster, yes, though the computational complexity can be essentially the same (O(1) push and pop)
16:23	sfuentes	ok so how can i have this O(1) for both push and pop in a queue?
16:23	vy	sfuentes: If you're sharing those queues among many other concurrent tasks, then you'll need to copy them for each thread instance, which will significantly decrease the performance. OTOH, if there will be a single thread fiddling with the queue it'll much more efficient to have a mutable queue implementation. To summarize, that all depends on the specific problem domain.
16:24	sfuentes	i know you mentioned PersistentQueue, but I'm trying to write this
16:24	sfuentes	implement this
16:24	Chouser	vy: even in single-threaded contexts, immutable collections are frequently worth while
16:24	vy	Chouser: +1
16:25	Chouser	sfuentes: you could look at what PersistentQueue does (it's written in Java) and do something similar in Clojure code.
16:25	sfuentes	Chouser: will do. thanks for the help
16:26	Chouser	sfuentes: sure, good luck!
16:47	manic12	I got clojure going with slime, and I realized something very important...
16:47	manic12	all my frustrations were because of netbeans.
16:48	manic12	maybe not all of them, but at least most of them
16:50	Chousuke	heh
16:50	Chousuke	now you can find new frustrations with emacs.
16:51	manic12	i have been using emacs for over ten years
16:51	Chousuke	hmm. I suppose you've found most of them then.
16:52	manic12	actually emacs is quite big, ten years isn't enough time to find all the frustrations
16:52	vy	Word.
16:53	Chousuke	well, yeah.
16:53	Chousuke	ten years isn't enough to find all the features
16:54	Chousuke	but that's okay. I have used emacs only for a couple months and I've found enough for a while
16:55	ben_m	My .emacs is so messy, I hate that :/
16:55	Chousuke	heh.
16:55	ben_m	My .vimrc is only 10 lines or something.
16:55	Chousuke	I have an emacs.d instead, based on emacs-starter-kit
16:56	hiredman	my vimrc is just over 200
16:56	Chousuke	it provides a good base for keeping things organised :)
16:56	ben_m	Chousuke: I should try that.
17:11	manic12	somebody should have warned me about netbeans
17:12	ben_m	What language do you come from? Before Clojure.
17:12	manic12	common lisp
17:12	ben_m	oh
17:12	ben_m	They should've warned you then.
17:12	ben_m	From my experience, only Java programmers actually like NetBeans.
17:19	sfuentes	i'm sorry, what's wrong with netbeans?
17:21	ben_m	I'm just not a fan of IDEs so I wouldn't know.
17:21	manic12	for clojure, it's like programming java with parens, but a little more frustrating
17:23	sfuentes	manic12: how so? i'm not a java programmer, but i'm learning clojure with netbeans.
17:24	manic12	when the repl doesn't stop by itself for a stack overflow or some other reason, you have to restart it yourself constantly
17:24	sfuentes	oh i see. so its a repl thing
17:24	sfuentes	is that all?
17:25	manic12	it's not a dynamic language without a fluid repl, as far as i am concerned
17:27	manic12	sfuentes: that's not all, I just don't want to revisit the pain
17:31	manic12	except of course to cut and paste the code I left there into an emacs buffer
17:34	ben_m	I still think it is the best IDE out there.
17:34	ben_m	Just because of jVi
17:34	Chouser	ben_m: have you used jVi with enclojure?
17:34	ben_m	I don't even know what Enclojure is.
17:35	Chouser	it's the clojure plugin for netbeans
17:35	ben_m	Oh :)
17:35	ben_m	I don't really use IDEs, but when I have to (school), then I use NetBeans.
17:37	jensli	Q: Im reading clojure.contrib.def.
17:37	jensli	In defnk theres a form: (-> arg name symbol)
17:37	jensli	Is because of a namespace thing, to make sure the sym gets interned in the right namespace?
17:39	hiredman	,(doc defnk)
17:39	clojurebot	"clojure.contrib.def/defnk;[[fn-name & fn-tail]]; Define a function accepting keyword arguments. Symbols up to the first keyword in the parameter list are taken as positional arguments. Then an alternating sequence of keywords and defaults values is expected. The values of the keyword arguments are available in the function body by virtue of the symbol corresponding to the keyword (cf. :keys destructuring). defnk accepts
17:40	hiredman	jensli: that is to turn the keyword into a symbol
17:40	hiredman	,(-> :foo name)
17:40	clojurebot	"foo"
17:40	hiredman	,(-> :foo name symbol)
17:40	clojurebot	foo
17:41	jensli	Right, so that they are avalible as syms in the func body. I see, cheers.
18:17	manic12	mystery solved: to call a native library, the function which loads the dlls must be AOT compiled
20:59	Chouser	rhickey: do you have any performance goals for finger trees?
21:00	rhickey	as fast as possible?
21:00	Chouser	yeah.
21:00	rhickey	I don't have any expectations really
21:01	rhickey	clear + fast is ideal
21:01	rhickey	what are the issues?
21:01	rhickey	or tradeoffs
21:02	Chouser	just diminishing returns on time I spend on it vs. performance improvements
21:02	rhickey	are you unhappy with where it's at?
21:02	Chouser	a bit
21:03	rhickey	do you know where the bottlenecks are?
21:03	Chouser	I've removed several, finding the next bottleneck takes more time than removing in usually.
21:04	Chouser	I haven't looked at it for several days, but I'm not relishing picking it up again.
21:04	rhickey	what kinds of things, and what kinds of speedups?
21:04	sproingie	is there any good introduction to finger trees that isn't in haskell?
21:05	Chouser	I was hopeful that when used as a queue (so no measurements involvements) that it would compete with PersistentQueues
21:05	Chouser	but it's really not. Still 6 to 8 times slower.
21:07	Chouser	I've removed most of the apply calls, which gave 15% to 30% improvement for many tasks.
21:08	Chouser	I moved all measure calculations into delays, which also meant some are cached which weren't before, and that gave another 7-15% boost for split operations.
21:16	rhickey	I imagine that the split/concat functionality would dominate the decision to use a finger tree
21:16	rhickey	for that there is no other game in town (at least in clojure)
21:20	Chouser	ok. well, there's probably some useful work I can still do there. measure still does more seq and map work than it probably has to.
21:36	rhickey	Chouser: yeah, one of the problems is that you have to avoid some of the high-level constructs when building low-level things
21:37	Chouser	sure, and I've removed those for a lot -- getting rid of (apply foo (concat ...)) constructs and similar has helped.
21:39	Chouser	but I haven't done that for the measure/reducer stuff yet.
22:17	rhickey	http://www.artima.com/articles/hickey_on_time.html
23:32	arohner	is there a way to clear the repl history?
23:48	dnolen	arohner: in slime?
23:51	arbscht	if you're using jline, it will be in a jline history file, probably ~/.jline-clojure.*.history