#clojure – 2009-09-29

2009-09-29

00:02	qbg	Is there a better way to make a big vector than to do (vec (repeat 1000000 0))?
00:03	duck1123	why do you want a whole lot of 0's
00:04	duck1123	that works, but there's probably a better way depending on what you really need
00:04	qbg	Trying to see just how expensive vectors are
00:04	qbg	and have some fun
00:05	duck1123	Clojure's vectors are pretty cheap. They're not the cheapest out there, but if you consider what they can do...
00:06	qbg	True, though making an int array is MUCH faster
00:07	qbg	And I run out of memory when trying to create a 10,000,000 element vector
00:07	duck1123	that's why you want to avoid holding the head
00:07	hiredman	well, that doesn't matter for vectors
00:08	duck1123	good point
00:08	qbg	I suppose all of the separate consing is probably the source of the time required
00:15	duck1123	is there a better way to say (if (not (nil? ...)) ...)
00:15	duck1123	I find myself doing that a lot lately
00:16	qbg	(if ...)?
00:16	duck1123	but I want false to be true
00:17	duck1123	and I'm a total Discordian for saying that
00:17	qbg	Then (if (not ...))?
00:18	duck1123	true also has to be true
00:18	duck1123	so, anything except nil is true
00:20	duck1123	no, if not nil? is as clear as it's going to get
00:21	hiredman	(def not-nil? (comp not nil?))
00:22	duck1123	that would still be (if (not-nil? which isn't much better
00:22	duck1123	I'll stick with what I have
00:22	hiredman	!nil?
00:22	hiredman	,'!nil?
00:22	clojurebot	!nil?
00:23	duck1123	has anyone made a -> that shortcuts on nils?
00:23	hiredman	-?>
00:23	hiredman	it's in contrib.core
00:23	duck1123	cool thanks.
00:24	duck1123	is contrib.core new?
00:24	hiredman	no idea
00:25	duck1123	I don't seem to have it in my jar
00:25	duck1123	I can't be more than a month old
00:25	hiredman	~def -?>
00:27	hiredman	the history says at it's been in contrib over three months
00:27	hiredman	more like six
00:28	duck1123	I wonder if I've been bitten by that bug that hlship reported
00:28	duck1123	I AOT my contrib
00:30	hiredman	and?
00:31	duck1123	he reported that some namespaces weren't being compiled. I'm just guessing why my jar didn't have it
00:32	hiredman	I also AOT the contrib jar clojurebot uses
00:32	hiredman	,(-?> nil .toUpperCase)
00:32	clojurebot	nil
00:33	duck1123	I don't know. I'm replacing it
00:46	qbg	Why would pmap be only about 2.2 times faster than map on a quad core machine when the mapped function is essentially as ideal as you can get?
00:47	duck1123	there's quite a bit of overhead on setting up pmap, so unless your fn is long enough, it might even be slower
00:48	qbg	Each function call takes around a quater of a second
00:49	duck1123	I'm sure you'd find that as the time your fn takes increases, so will your performance increase
00:50	qbg	Would the same thing be true with agents?
00:50	hiredman	pmap uses futures which use the same threadpool as agents
01:03	qbg	Even when the function takes 30 seconds to compute, I don't see much more than a 2.4x speed up
01:04	hiredman	how are you consuming the result?
01:04	qbg	nth
01:04	qbg	(of the last element)
01:07	qbg	Entering all of the code in the repl wouldn't be a problem, right?
02:03	j3ff	Is there a sort of "do nothing" command in clojure?
02:04	salainen	for what?
02:05	j3ff	i have an if statement in a recur, and when the recur is over i want it to do nothing. right now i just have it as "nil" but i dont want it to return anything
02:05	j3ff	i mean the if statement is the base case
02:06	Makoryu	j3ff: You can't not return anything.
02:06	j3ff	ah ok
02:06	salainen	j3ff: so just ignore the return value. nil means "nothing"
02:06	Makoryu	j3ff: There's no difference between expressions and statements in Clojure, unlike whatever language you're probably used to
02:07	_mst	you might prefer (when test foo) to (if test foo nil)
02:07	salainen	(ok.. nil probably does not mean nothing, but rather unknown ... but what the heck)
02:29	konr	What should I use to make GET/POST requests and parse HTML?
02:30	hiredman	are you looking for something like a web browser interface?
02:30	hiredman	htmlunit is pretty nice for filling out forms and website scraping, etc
02:31	hiredman	there are several http client libs, on in contrib
02:31	hiredman	tagsoup does a great job parsing html
02:32	konr	Hmm, interesting... I'll take a look at this tagsoup, thanks!
03:07	Fossi	hi
04:11	j3ff	hey fossi
04:59	j3ff	whats up clojure people
05:16	konr	how can I find out what java libraries are available to me? I'm struggling to import tagsoup :S
05:19	fullets	Is there a more idiomatic way to write (some (fn [x] (when (= (foo x) bar) x)) a-list-or-something)?
05:29	Fossi	Chouser: the error-kit handle map destructure isn't really intuitive
05:29	Fossi	took me about half an our to figure out that you have to use the names in the vector that you used on defining the error
05:29	sunwukong	fullets: (filter #(= (foo %) bar) a-list-or-something)
05:30	jdz	sunwukong: that's not the same
05:30	Fossi	especially with the 'defnish' vector, it lead me to believe it was just a 'normal' bind
05:30	sunwukong	jdz: ah, ok
05:31	jdz	fullets: what exactly do you want to do? because the when in your function is unnecessary
05:32	fullets	jdz: If I just have (= (foo x) bar) the form evaluates to true rather than the matching item in the sequence; what I'm looking for is an equivalent of the CL (find bar sequence :key #'foo)
05:32	jdz	,(doc some)
05:32	clojurebot	"([pred coll]); Returns the first logical true value of (pred x) for any x in coll, else nil. One common idiom is to use a set as pred, for example this will return true if :fred is in the sequence, otherwise nil: (some #{:fred} coll)"
05:33	jdz	oh, i seem to remember "some" working differently
05:33	fullets	,(some (fn [x] (= 1 x)) [1 2 3])
05:33	clojurebot	true
05:33	fullets	I want that to eval to 1
05:34	fullets	,(some (fn [x] (when (= 1 x) x)) [1 2 3])
05:34	clojurebot	1
05:34	sunwukong	,(first (filter (fn [x] (= 1 x)) [1 2 3]))
05:34	clojurebot	1
05:34	Chousuke	,(first (filter #{2} [1 2 3]))
05:34	clojurebot	2
05:35	jdz	missing the :key here
05:36	Chousuke	hm
05:36	konr	Guys, I have tagsoup-1.2.jar in my classpath. I've opened it, and it contains "org/ccil/cowan/tagsoup/Parser.class". Yet when I try to import it via (import '(org.ccil.tagsoup Parser)), I get a ClassNotFoundException. Where am I getting it wrong?
05:37	jdz	konr: missed cowan?
05:37	konr	jdz: nope, just a typo in my previous message ;)
05:37	konr	(import '(org.ccil.cowan.tagsoup Parser))
05:38	jdz	konr: check your classpath, it works for me.
06:03	cschreiner	konr: seems similar to my experience
06:04	konr	cschreiner: it turned it to be a problem on the classpath
06:04	cschreiner	I'm running emacs on 10.6.1
06:05	cschreiner	(never could get that classpath-thing right)
06:09	konr	Hmm, I don't know how it works on emacs, but using vi/ng-server, we run a JVM as a server and connect to it using a client, so changing the classpath was just a matter of changing the parameters used to run the server
07:15	konr	anyone knows where I can find zip-query.clj? It's referenced in (doc xml->), but it's not in $CLOJURE_CONTRIB
07:34	ngoc	Does coordination in ref mean the same thing as in "cooperative multitasking"?
08:01	Fossi	ngoc: afaik it means changes to more than one variable
08:02	vy	I'm reading the documentation of ensure: "Protects the ref from modification by other transactions. Returns the in-transaction-value of ref. Allows for more concurrency than (ref-set ref @ref)". I still couldn't figure out what ensure does. Could anybody help please?
08:08	Fossi	it ensure's that a ref you don't write to, but only read has a certain value
08:08	Fossi	otherwise it wouldn't be protected from manipulation
08:09	Fossi	normally a transaction would be retried only if your writes clash with somebody elses
08:09	vy	Is there any example code using "ensure"?
08:14	Fossi	i don't have any and couldn't find one in a short google trip
08:15	Fossi	i guess it's not needed very often. just to detect the write-skew
08:41	vy	Why does (#(1)) try to cast 1 to IFn and hence complains that "java.lang.Integer cannot be cast to clojure.lang.IFn".
08:43	Chouser	,(macroexpand '(#(1)))
08:43	Chouser	vy: that expands to: ((fn* [] (1)))
08:43	vy	Oops! I see. My bad.
08:43	Chouser	np. It's a common mistake.
08:48	vy	What's wrong with (send a #(fn [v & _] (Thread/sleep 1000) (conj v 1))), after executing this and trying @a, Clojure complains that "Agent has errors".
08:49	Chouser	what was a?
08:49	vy	Chouser: [1]
08:50	vy	(agent [1]) ofcourse I mean.
08:50	Chouser	drop the #
08:51	vy	Brrr!
08:52	Chouser	got it now? :-)
08:52	vy	Yes, I already smacked my head.
09:07	ambient	anyone have a tutorial or something how to install penumbra to ubuntu, because it seems to be beyond me?
09:07	ambient	i can do a very difficult install, where i add a million paths to different places but there must be a simpler way to do it all
09:12	ambient	seems i have to build my own packaging system
09:14	Dominik_S	hello, i want to integrate a repl in a existing java project
09:15	ambient	do i have to create a single environment into which i copy&paste all the needed dependencies (clj source code) in order to be able to use them later and put the directory into classpath?
09:17	Chouser	ambient: no, commands like 'use' and 'require' search the whole classpath, so you can add as many different directories as you want to.
09:18	ambient	Chouser: just create a single directory like ~/libs/clojure, add it into classpath, and copy&paste all dependency clojure code there?
09:19	Chouser	ambient: I wouldn't recommend copy&pasting code
09:19	ambient	copying the files and the directory structures
09:19	ambient	src/*
09:20	Chouser	I know some people recommend that. I personally use -Djava.ext.dirs to point to a directory where I have symlinks to all the .jar's I might need.
09:21	Fossi	Chouser: seen my comments on error-kit?
09:21	ambient	i'd rather make a system that's highly dynamic so that I don't have to manually do anything except copy some files
09:22	Chouser	Fossi: I have now, thanks.
09:22	Fossi	i'm still a bit confused on how it should actually be used
09:23	Chouser	Fossi: I'm thinking about ripping out deferror and the error constructor and inheretance stuff.
09:23	Dominik_S	hello everyone, is there a tutorial for integrating a clj repl in a existing java project?
09:23	Fossi	deferror has that args-destruct-map parameter that i can't really wrap my head around
09:24	Chouser	Fossi: so one way to use it would be to specify all details of the error when you raise it -- if you want to craete your own fn to create similar types of errors you'd do that on your own.
09:24	Fossi	since it doesn't really seem to work with nested maps as in the binding
09:24	Fossi	Chouser: sounds valid
09:26	Chouser	I think that my cut out a lot of unnecessary complexity in an already necessarily complex lib.
09:26	Chouser	Dominik_S: I don't know of a tutorial -- did you search the google group? I know it's been asked about and done a few times.
09:29	Dominik_S	i search the google grp, but i did't found. are there some special key words for that?
09:41	Fossi	we'd love to have serializable keywords and apparently that's fixed in master, does the next release have any fixed date yet?
09:42	ambient	this is strange "Could not locate clojure/contrib/def__init.class of clojure/contrib/def.clj on classpath" even if both clojure and clojure-contrib jars are in classpath
09:47	chouser	Fossi: no fixed date.
09:48	chouser	Fossi: but you can grab a current snapshot of the repo and just use that.
09:52	Kjellski	Hi there =)
09:53	Kjellski	Someone has got a minute or two for a small piece of code I´m trying to translate?
09:56	Kjellski	I´ve got a solution, but it looks so extremely ugly, that I think there would be a better way...
09:56	chouser	lisppaste8: url
09:56	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
09:56	chouser	Kjellski^^
09:57	Kjellski	Oh thanks, I´ve already prepared some pastebin urls:
09:58	Kjellski	http://pastebin.org/29410
09:58	Kjellski	I´ve translated into:
09:58	Kjellski	http://pastebin.org/29413
09:58	Kjellski	It´s about the simple rot13 "cypher" ^^
10:00	Kjellski	And btw, the result looks ugly too.
10:04	chouser	I'd try writing it as a seq processor.
10:05	Kjellski	Okay, where can I read through how that goes?
10:06	Fossi	chouser: thanks, we rather patched stable ;)
10:08	Kjellski	Or can you tell me where I could find a version to compare with?
10:19	ambient	(require) seems to search for root resource <classpath>/x/y/z/z.clj from (require x.y.z), how do i make it <classpath>/x/y/z.clj?
10:22	lisppaste8	Chouser pasted "rot13 for Kjellski" at http://paste.lisp.org/display/87892
10:22	raek	ambient: how does your (require) line look like?
10:23	Kjellski	Ufff... thanks a lot Chouser! ... reading
10:25	Kjellski	What does the -> thing?
10:25	chouser	Kjellski: note there's no IO -- doseq and print are side-effecty things and will tend to make your code uglier, especially when you don't need it.
10:26	chouser	-> is a macro that takes each expression and inserts it as the first arg of the next expression
10:26	chouser	so (-> i (- base)) is the same as (- i base)
10:26	Kjellski	Damned, that sounds extremely useful... and now I can read the code much better =)
10:27	ambient	raek: (require 'examples.gears)
10:29	Kjellski	Thanks a lot... I think the best thing is that I can see how clojure was used in the right way =)
10:32	LauJensen	ambient: You guys still haven't gotten penumbra working?
10:34	raek	ambient: and your sourcefile is in <classpath>/examples/gears.clj ?
10:35	ambient	raek: yes
10:35	ambient	LauJensen: no
10:36	raek	i'm really a java noob so this is just a guess, but i've heard that you should have at least two levels of directories
10:36	raek	and java might be enforcing this
10:36	chouser	only need one dir. examples.gears for examples/gears.clj should be fine
10:37	LauJensen	What I did was, copy the native files into ~/deps and the source into /libs/penumbra/, then EXPORT LD_LIBRARY_PATH=$LD_LIBRARY_PATH:~/deps/ and then java -cp clojure.jar:/libs/penumbra/src/ clojure.lang.repl, and then (use 'examples.gears) . What are you doing idfferently ?
10:37	LauJensen	"~" is shorthand, I always use fully qualified names
10:37	ambient	clojure.main
10:37	LauJensen	sure :)
10:37	LauJensen	Same thing
10:38	ambient	well i did (println (seq (.getURLs (java.lang.ClassLoader/getSystemClassLoader))))
10:38	ambient	and it shows that the correct path exists
10:38	ambient	penumbra/src
10:40	ambient	java.io.FileNotFoundException: Could not locate examples/gears__init.class or examples/gears.clj on classpath: (NO_SOURCE_FILE:0)
10:40	ambient	im boggled
10:46	lisppaste8	cgrand annotated #87892 "another rot13 for Kjellski" at http://paste.lisp.org/display/87892#1
10:58	Kjellski	Hey cool, that´s another nice idea =) thanks cgrand!
11:09	Kjellski	So thanks again folks, I´m leaving! cya
11:28	johnmn3	hello all
11:28	johnmn3	I followed the tutorial here: http://freegeek.in/blog/2009/08/setting-up-emacs-clojure-with-emacs-starter-kit/
11:29	johnmn3	and I want to get paredit working
11:29	johnmn3	anyone have familiarity with this setup?
11:31	prospero_	hey, I'm a bit late to this, but I saw a conversation in the logs about not getting Penumbra to run
11:31	johnmn3	doing a M-x paredit-mode RET gets it going just fine. However, I'd like to enable "Electric RET" so that I can manipulate which lines expressions can go on
11:32	prospero_	did I just give bad advice here: http://wiki.github.com/ztellman/penumbra/getting-started
11:33	prospero_	it's worked for me on os x and windows
11:33	prospero_	but maybe I'm just eliding a step or something
11:34	danlarkin	prospero_: that's okay advice for java6, but not for java5
11:34	danlarkin	you don't want to go messing around with your java.library.path on java5...at least in my experience
11:35	prospero_	danlarkin: so for java5 you need to place the files in the right place?
11:37	danlarkin	I don't know where jnilib and so files have to go
11:37	prospero_	ok
11:37	prospero_	but for java 6, the script seems solid?
11:38	danlarkin	seems so, worked for you anyway
11:38	prospero_	yeah, fair enough
11:38	prospero_	ok, thanks
11:38	rsynnott	does clojure build on java 6 these days, actually?
11:41	Makoryu	I'd be amazed if it did not
11:46	tmountain	rsynott: it definitely does
12:18	Fossi	PersistentHashMap$BitmapIndexedNode not being serializable. rings a bell for someone?
12:46	Drakeson	is swank-clojure broken these days?
12:47	technomancy	Drakeson: if it is please let me know!
12:49	Drakeson	well, it might be some change in clojure itself or maybe my own local configurations. When I try to compile it (or `use') it, it produces this error message: [java] java.lang.ClassFormatError: Duplicate method name&signature in class file swank/util/io/proxy$java/io/StringWriter$0 (io.clj:23)
12:50	tomoj	I have the latest swank-clojure and didn't have any problem
12:51	Drakeson	tomoj: do you have the latest clojure, too?
12:51	tomoj	ah, no, I had last week's
12:52	Drakeson	last week it was fine
12:52	technomancy	Drakeson: I've been sloppy about keeping in sync with jochu's repo. are you using his or mine?
12:52	Drakeson	I am using his tree.
12:52	technomancy	I haven't gotten a chance to look at that yet. try mine?
12:53	Drakeson	technomancy: most likely the same. I'll try yours too. do you have the latest clojure now?
12:54	technomancy	Drakeson: I'll update just to be sure
12:54	tomoj	ah I'm using technomancy's as well
12:56	technomancy	Drakeson: works with today's clojure.
12:56	technomancy	at least, M-x swank-clojure-project does
12:56	Drakeson	technomancy: thanks. I'll try yours in a moment ...
13:00	Drakeson	oh, he is now producing swank-clojure.jar
13:00	johnmn3	broke my emacs some how: M-x slime [no match]
13:01	johnmn3	was working after I followed the instructions and installed everything, but after restarting emacs, no joy
13:01	technomancy	johnmn3: do you have (clojure-slime-config) in your .emacs file?
13:02	technomancy	johnmn3: never mind; I see the problem
13:02	johnmn3	I actually don't have an .emacs file.. how do you see the problem?
13:03	technomancy	johnmn3: some of the autoloads are in the wrong order
13:03	johnmn3	I have an .emacs.d folder
13:03	technomancy	works with swank-clojure-project but not with simple M-x slime.
13:03	technomancy	johnmn3: that's what I meant
13:03	technomancy	file, folder; same thing.
13:04	johnmn3	oh. if it gets fixed, will doing an clojure-update fix it?
13:05	technomancy	johnmn3: that's part of clojure-mode unfortunately, so you'll need to update that
13:07	Drakeson	technomancy: I still have the issue (even using your tree). Something might be broken locally (maybe debian guys broke something). Please don't consider this as a bug report, yet :)
13:07	johnmn3	I did it once and it started compiling stuff.. but still no worky
13:08	johnmn3	clojure-mode is there
13:09	technomancy	Drakeson: I'm seeing that problem here with M-x slime
13:09	technomancy	I don't use slime on its own usually, I use it in the context of a project, so I must have missed it
13:09	technomancy	I think it just needs to be upgraded to work with the latest clojure
13:10	Drakeson	technomancy: thanks
13:10	technomancy	I forgot that in the project context it will just use whatever version of clojure the project depends on, not necessarily the latest.
13:11	tomoj	so swank-clojure is broken with latest clojure?
13:12	technomancy	tomoj: not for long, hopefully. =)
13:16	johnmn3	so how do I get into clojure-mode
13:17	technomancy	johnmn3: if you use it on a project basis, you can use elpa (http://tromey.com/elpa) but if you want standalone slime you'll have to give me a minute
13:17	Drakeson	technomancy: it is broken with clojure origin/master~3 but not with origin/master~4
13:17	technomancy	Drakeson: good to know; thanks
13:20	johnmn3	technomancy: oh, no, no worries bro
13:22	somnium	what does a single ^ mean prefixed to a symbol (seeing it in zip.clj)
13:22	technomancy	somnium: it's a shortcut for meta
13:22	rhickey	^ == (meta x)
13:23	somnium	thanks
13:36	chouser	rhickey: ^ not deprecated yet?
13:37	rhickey	Chouser: there was a conversation here about how best to deprecate, given that it is a reader thing, I don't know that we concluded anything
13:37	rhickey	but I'd like to deprecate, yes
13:39	manic12	so someday you could have a regular symbol like m^2 ?
13:40	somnium	would it be possible to get the reader to parse % as part of a symbol outside of a #() fn ?
13:40	rhickey	manic12: not necessarily, the point of deprecating ^ was so that it could replace #^
13:41	rhickey	both ^ and % are currently terminating, making them not is also an independent decision
13:42	somnium	or as part of a kewyword? always terminating on %, makes implementing dsl for say, css, awkward
13:44	rhickey	somnium: understood
13:45	chouser	somnium: you know % is available for DSLs and used in some already?
13:46	somnium	how?
13:46	rhickey	Chouser: not as a constituent character
13:46	rhickey	,'foo%bar
13:46	chouser	just as a plain symbol char
13:47	chouser	,(let [% 5] %)
13:47	somnium	ah
13:47	chouser	clojurebot is letting us down
13:47	somnium	so something like (mydsl 100 %)?
13:47	chouser	oh, but I was thinking of ~ and ~@
13:47	somnium	still have to parse it specially
14:52	hircus	hi folks
14:53	hircus	would a Linux distribution be better advised to ship Clojure 1.0, or a later snapshot?
14:54	Raynes	Clojure 1.0, I suppose.
14:56	chouser	depends on your users, I suppose. Are you a Debian Stable type distro, or a Gentoo ~x86 type distro?
15:08	technomancy	java.lang.ClassFormatError: Duplicate method name&signature in class file <= would you get that error when trying to write a proxy that defines a method twice?
15:09	technomancy	hah; I'm looking at this code thinking "why's he using a ref there; he should use an atom."
15:09	technomancy	C-x v g tells me the code was written before atoms were implemented.
15:09	technomancy	(this is in swank-clojure)
15:11	technomancy	,(proxy [java.io.StringWriter] [] (close [] ))
15:11	clojurebot	java.lang.IllegalStateException: Var null/null is unbound.
15:11	technomancy	^ in current clojure master, this raises an exception
15:11	technomancy	I can't see how it should
15:13	crios	hello. Could anyone explain a bit what does "holding the head" mean? It seems related to Var declaration, and I gathered it affects the overall runtime performance. Till now I understood that as a "keeping a reference which is not Garbage colleted"
15:13	crios	[collected]
15:13	technomancy	crios: that's about right
15:14	kotarak	crios: "holding the head" means the you store the head of sequence somewhere, in a local, a Var, a Ref, etc. which prevents GC of the sequence.
15:14	kotarak	so eg. (iterate inc 0) will eventually eat all your memory when traversing it and holding the head somewhere.
15:14	technomancy	if you loop over a lazy sequence, it should normally allow the elements you've already used to be GC'd... otherwise if there's a reference to the head it's a memory leak
15:14	crios	Is it an issue on functional languages in general? Or just Clojure's Java implementation?
15:14	technomancy	crios: it's a laziness issue
15:16	technomancy	commit a780e1d096f6a99cb974568a0a6d76d4e996e585 seems to have broken proxying to StringWriter
15:16	crios	So in order to be "holded", the sequence must be holded in a "named reference"
15:17	Chousuke	crios: any reference to it will do
15:17	Chousuke	so if you put a lazy seq in a map, that counts
15:17	kotarak	crios: local, in a map, in a vector, ...
15:17	technomancy	Drakeson: I don't think this is a swank-clojure bug
15:17	technomancy	stick with master~4 for now
15:20	kotarak	Can c.l.Compile set warn-on-reflection?
15:20	chouser	technomancy: confirmed that patch broke your proxy example.
15:20	technomancy	chouser: it doesn't look like it's directly related to proxy
15:21	chouser	no indeed
15:21	technomancy	must be just the way proxy relies on TransientHashSet
15:21	technomancy	somehow
15:21	chouser	:-)
15:21	crios	kotarak: when running "(iterate inc 0)" on the REPL I'm holding the head?
15:22	kotarak	crios: I would think so, because the repl stores the last expression in *1.
15:22	kotarak	The value of the last expression, that is....
15:23	kotarak	Since the Repl prints the sequence. It realises it.
15:23	kotarak	Should give some memory trouble....
15:24	crios	I'm running it ...
15:24	crios	mmm stopped after a while
15:25	ambient	are the jvm summit 2009 talks coming on the web sometime in the future?
15:25	crios	no crash, tough
15:25	kotarak	crios: what did it say, when it stopped?
15:25	crios	nothing, returned to the REPL's prompt
15:26	crios	the last showed number: 1020140
15:26	chouser	technomancy: I gotta run, but that patch is clearly braking sets somehow.
15:26	chouser	breaking
15:26	technomancy	chouser: I'll look into it later today
15:27	crios	ah no wait kotarak: the output was mixed
15:28	crios	scrolling back, I found: java.lang.OutOfMemoryError: Java heap space
15:28	crios	now it makes sense :)
15:28	kotarak	crios: bingo :)
15:28	crios	so, all lazy sequence have an hold-to-the-head?
15:29	kotarak	crios: ?? They all have the same problem, if the sequence is bigger than your memory. If that is, what you are asking.
15:30	slyrus_	hmm... is swank-clojure busted?
15:30	technomancy	slyrus_: clojure is busted. =)
15:30	technomancy	see chouser above
15:30	kotarak	crios: (take 5 (iterate inc 0)) is also lazy, but it shouldn't be a problem to hold unto its head. ;)
15:30	slyrus_	oic... thanks technomancy
15:31	Chousuke	crios: a lazy sequence itself doesn't cause OOM situations, it's the consumer's carelessness that ultimately causes trouble :)
15:33	crios	it is holding my head :) - The consumer should care to not execute an infinite loop, and this is obvious. So that's all about this "holding the head"?
15:35	crios	I mean, no declaration / scope issue there?
15:35	kotarak	crios: bad => (let [x (iterate inc 0)] (realise-a-huge-part-but-dont-hold-head x)), good => (let [x (fn [] (iterate inc 0))] (realise-a-huge-part-but-dont-hold-head (x)))
15:38	Chousuke	crios: well, sometimes you end up having references to things where you wouldn't expect them
15:39	Chousuke	crios: but you just need to double-check your code if you get OOM exceptions :)
15:41	crios	kotarak, in your "good" code, your are creating a function so that the reader does not evaluates that iteration as soon as it read it (causing an infinite loop). Correct?
15:42	kotarak	crios: no. The reader does not evaluate anything. (At least not in general). The bad code stores the head in a local. The good just passes the return value of the function (the sequence) on to the next function. So the sequence head is not stored in a local.
15:43	Chousuke	of course, the example is a bit silly :P
15:44	Chousuke	usually you'd just do (realise-a-huge-part... (iterate inc 0)) :)
15:44	kotarak	Chousuke: examples tend to be silly or too huge
15:44	crios	I have to study this chat session carefully, for a while
15:44	crios	thank you both
15:45	kotarak	crios: np
16:08	crios	to stay in topic ... in the mailing list, a new question: "RFC: laziness-safe, semi-dynamic environment Var(Lite)"
16:09	crios	a Request for Comments
16:09	crios	I read it and my head is hold (down)
16:09	crios	'night
16:09	crios	:)
16:15	ngoc	How to call namespace/func dynamically?
16:15	ngoc	Something like this pseudo code:
16:16	ngoc	(def my-ns 'foo)
16:16	ngoc	(def my-func 'bar)
16:16	ngoc	(my-ns/my-func args)
16:17	chouser	,(resolve (symbol "clojure.core" "map"))
16:17	clojurebot	#'clojure.core/map
16:17	chouser	,((resolve (symbol "clojure.core" "+")) 5 10)
16:17	clojurebot	15
16:17	somnium	,(ns-resolve 'clojure.core 'map)
16:17	clojurebot	#'clojure.core/map
16:22	ngoc	It works, thank you very much
16:23	somnium	,(type "foo")
16:23	clojurebot	java.lang.String
16:23	somnium	,(type 'bar)
16:23	clojurebot	clojure.lang.Symbol
16:23	somnium	,(type (symbol "foo"))
16:23	clojurebot	clojure.lang.Symbol
16:23	somnium	(ns-resolve "foo" "bar")
16:24	somnium	,(ns-resolve "foo" "bar")
16:25	somnium	where'd he go? I get a java.lang.String cannot be cast to clojure.lang.Symbol
16:25	somnium	which seems incongruous given the above cast
16:26	chouser	'symbol' is not a cast. It's a fn.
16:26	somnium	ah
16:26	chouser	,(name 'foo)
16:26	clojurebot	"foo"
16:26	chouser	,(name "foo
16:26	clojurebot	EOF while reading string
16:26	chouser	,(name "foo")
16:26	clojurebot	java.lang.ClassCastException: java.lang.String cannot be cast to clojure.lang.Named
17:00	somnium	question about the reader, at macro expand time: (vector :foo :bar) is a persistent list containing three unevaluated expressions, but [:foo :bar] is a persistent vector containing two unevaluated expressions?
17:03	Chousuke	somnium: the data structures produced by the reader are such, yes.
17:04	ngoc	How to add a key -> value pair to an existing hash? I do (cons {:k1 1} {:k2 2}) but it seems the result is incorrect.
17:04	Chousuke	use conj
17:05	Chousuke	,(conj {:foo 'bar} [1 2])
17:05	clojurebot	{1 2, :foo bar}
17:05	kotarak	somnium: they contain keywords (and in one case a symbol)
17:05	ngoc	Ah, conj works, thank you
17:05	kotarak	,(assoc {:foo 1} :bar 2)
17:05	clojurebot	{:bar 2, :foo 1}
17:06	somnium	is there an equivalent to conj that always appends to the end of seqable?
17:07	somnium	,(conj [1 2] 3)
17:07	clojurebot	[1 2 3]
17:07	hiredman	no
17:07	somnium	,(conj '(1 2) 3)
17:07	clojurebot	(3 1 2)
17:07	Chousuke	somnium: sequences only grow at the head
17:07	Chousuke	though there is concat
17:07	kotarak	,(concat (list 1 2) [3])
17:07	clojurebot	(1 2 3)
17:10	raek	conj isn't defined to append to the front, it adds something to a container in a container-specific way
17:11	prospero_	ambient: are you still having issues with Penumbra?
17:11	technomancy	chouser: I'm afraid that TransientHashSet/proxy problem is beyond me
17:11	prospero_	if so, send me a message on Github telling me exactly what your setup is, and I'll try and see how to get it working for you
17:12	technomancy	it looks like that patch is totally additive; I can't trace it to how it affects proxy
17:12	ambient	prospero_ nah, i got it to work on windows. ubuntu might've had some binary incompatibilities or such
17:12	prospero_	hmm
17:12	prospero_	I think Lau got it working on Linux
17:12	prospero_	but maybe not Ubuntu
17:13	prospero_	I've been leaning heavily on JOGL being cross-platform, I haven't had the time to test it across a wide variety of configurations
17:13	ambient	yeah, had to install 32 bit JVM because couldn't find 64 bit binaries
17:13	prospero_	hmm
17:14	prospero_	oh, right, because I only put 32-bit binaries in the lib folder
17:14	prospero_	ok, I'll fix that tonight
17:14	LauJensen	prospero_: Works fine on Ubuntu
17:14	prospero_	LauJensen: 32-bit?
17:15	LauJensen	Yep
17:15	ambient	i'm just very apt at f*n things up. mine was 32-bit also
17:16	prospero_	I assumed a 64-bit OS would be backwards compatible w/ 32-bit binaries
17:16	prospero_	is that not true?
17:16	ambient	it is but 64 bit JVM isn't
17:16	ambient	apparently
17:16	prospero_	hmm
17:16	prospero_	well, glad you got it running somewhere
17:16	ambient	heh thanks
17:16	prospero_	don't be shy about letting me know about these issues
17:17	prospero_	I'm trying to get a feel for common issues
17:17	LauJensen	prospero_: You're the Tellerman ?
17:17	prospero_	LauJensen: yes
17:17	prospero_	probably should just come on here as ztellman
17:18	LauJensen	Great to have you in here :) I noticed your doc-strings are mangled due to the macro-expansions that are taking place. I think it would be a great help in minimizing the learning curve if you could fix that.
17:18	ngoc	Since program = code + data, we usually need to encapsulate code and data together. What are "good" ways to do the encapsulation in Clojure? I think just like C, we use struct to do this?
17:19	Chousuke	ngoc: this is no problem in clojure, as code = data, so program = data + data ;)
17:19	ambient	lists :p
17:19	prospero_	LauJensen: can you give me an example?
17:20	LauJensen	prospero_: I think it was draw-points that I noticed it with, the doc string in slime will read "_ __BODY@@A_" or something along those lines
17:20	Chousuke	ngoc: don't worry about encapsulation too much.
17:20	prospero_	weird
17:20	Chousuke	ngoc: most of your functions should be processing immutable data structures, and you really don't need to protect those much :/
17:21	prospero_	I'm doing a few macros-within-macros, maybe that's it?
17:21	Chousuke	ngoc: as long as the input to your function is valid and it is immutable, no-one is going to be able to cause havoc from "outside" :)
17:22	somnium	,(let [a '(fn [x] (println x))] ((eval a) a))
17:22	clojurebot	DENIED
17:22	Chousuke	ngoc: and if someone calls your functions with improper input, that's their problem :P
17:22	LauJensen	prospero_: Yea I think so
17:23	ngoc	Chousuke: In Java most of the time we define a class, then create objects from the class. In Clojure do we usually need to do this way?
17:23	somnium	ngoc: what does a class actually do?
17:23	chouser	technomancy: ok, don't worry about it.
17:24	albino	It bundles the methods into a container?
17:24	Chousuke	ngoc: just use plain vectors, sets, maps and sequences as much as you can. of course, you can document that a function returns something and the user should not care that it's actually just a vector
17:24	ngoc	A class wraps code and data (state)
17:24	somnium	its more or less a hashmap of fields and functions right?
17:24	chouser	technomancy: it appears to be building the set of bridge methods incorrectly -- still trying to figure out what exactly and why.
17:24	Chousuke	ngoc: yeah. and state is bad :)
17:24	Chousuke	(uncontrolled)
17:25	technomancy	chouser: so does proxy actually use transient sets?
17:26	Chousuke	ngoc: with clojure, there's usually no need to bundle functions with the precise data type they work with.
17:26	ngoc	I think state is not bad, uncontrolled mutation is bad. In Erlang we store state in a function loop.
17:26	chouser	technomancy: yep, via into
17:27	Chousuke	ngoc: right. I was mostly referring to the OOP way of wrapping a bunch of state in an object and then thinking that somehow solves the problem :P
17:27	hiredman	state is bad
17:28	hiredman	it makes processes non-functional
17:28	somnium	- (defn cat [name, color] {:name name :color color :purr (fn [] "meow")})
17:28	hiredman	state gets in the away of repeatability and adds complexity
17:28	Chousuke	ngoc: just look at the core functions. many of them work with sequences. they don't care what the actual input is, as long as you can make a sequence out of it.
17:28	hiredman	state makes reasoning about code harder
17:29	ngoc	I come from Java and Erlang. I tend to use agent and struct all the time. I feel these are not the "Clojure way", but don't know how to do.
17:29	Chousuke	ngoc: well, first realise that structmaps are just regular maps optimised to share a set of keys.
17:30	Chousuke	and agents are fine, but you might want to look at refs and atoms too, for concurrency.
17:33	ngoc	(defn cat [name, color] {:name name :color color :purr (fn [] "meow")}) <-- this constructor is what I mean "struct", is there problem of structuring Clojure programs this way?
17:34	Chousuke	nah.
17:35	cemerick	ngoc: that's all we do, aside from a little special sauce on the side to allow us to treat the struct as an instance of a given Java interface from that side of things.
17:36	hiredman	ngoc: why put the function in there?
17:37	somnium	... it would have made more since if the output closed over name and color, my fault
17:37	hiredman	nah
17:37	Chousuke	as a silly example, consider a "birthday" function in a life simulator or something; it takes a creature and increments its age by one. in OOP you'd have Creature class with a creature.birthday() or something. in Clojure, I'd just do (defn birthday [thing] (update-in thing [:age] inc)) and represent my things as simple maps with the :age key. the fun thing is, that the birthday
17:37	Chousuke	function works for updating any associative thing with an :age key; not just subclasses of Creature
17:37	Chousuke	that's the kind of polymorphism I like /:
17:37	hiredman	closures and objects are the same thing, replacing one with the other does nothing
17:38	hiredman	you are better off using multimethods
17:38	ambient	there is only lambda :o
17:39	ngoc	hiredman: another way is (defn cat [name, color] {:state {:name name :color color}, :klass 'cat}), and in cat.clj: (defn purr [] "meow")
17:40	hiredman	ngoc: sure, but what if you have other animals
17:40	hiredman	(defmulti happy (comp type first list))
17:40	technomancy	why does into create fns and call them immediately instead of just calling loop?
17:41	ngoc	hiredman: Which means "cat.clj" is a Java class but it contains only code, data is stored outside
17:41	hiredman	no
17:41	chouser	technomancy: I think rhickey said that was an artifact on an earlier implementation that just hasn't been cleaned up yet. or something.
17:42	technomancy	chouser: gotcha
17:42	chouser	technomancy: the problem is invoked at line 218: bridge? (reduce into #{} (map second mb))
17:42	hiredman	ngoc: data is not "stored" outside
17:42	hiredman	there is no outside
17:42	chouser	change that to bridge? (reduce (partial reduce conj) #{} (map second mb)) and it works fine
17:44	technomancy	chouser: but does it indicate a problem with into?
17:44	chouser	not into itself
17:45	technomancy	right, but with the persistent hash set
17:45	technomancy	which bubbles up via into
17:45	chouser	yes
17:45	chouser	(count (into {} (map #(vector % %) badseq))) ==> 6
17:45	chouser	(count (into #{} badseq)) ==> 2
17:45	chouser	oh, wait...
17:47	ngoc	hiredman: I mean we must pass data to all functions in cat.clj when we call them, thus data is stored "outside"
17:47	hiredman	outside of what?
17:48	somnium	felix.purr vs. (purr felix) ?
17:48	kunley	Hi.
17:48	ngoc	hiredman: outside cat.clj
17:48	hiredman	,(-> felix purr)
17:48	clojurebot	java.lang.Exception: Unable to resolve symbol: purr in this context
17:49	kunley	Is there a way to interrupt a current call without killing REPL?
17:49	hiredman	ngoc: cat.clj is a source file, are you saying you store data in you source files?
17:49	hiredman	your
17:51	hiredman	if I create a new Object what source file does it live in?
17:52	ngoc	hiredman: I mean "define". OK if I write cat.clj this way, it's just like using C to write program in OOP style. Is there another way?
17:52	hiredman	ngoc: but you did define the it in side cat.clj
17:53	hiredman	(defn cat [name color] {:name name :color color})
17:53	hiredman	there, it is defined
17:53	technomancy	chouser: I can't trigger incorrect behaviour calling into with a set myself
17:53	technomancy	though I guess the stuff that proxy is doing is a lot more complicated than what I'm trying
17:54	chouser	technomancy: well, it's a set of Methods which may be part of the problem.
17:54	technomancy	wow; that function is two lines short of 200
17:55	ngoc	(defn cat [name color] {:name name :color color}) <- this is a constructor to create a cat state. Anyway what's your point? What do you want to say?
17:57	somnium	ngoc: it doesn't create state, it creates an immutable map
17:57	serp_	I think a cat has more properties than name and color
17:57	hiredman	ngoc: what state?
17:57	hiredman	that constructs an immutable cat value
17:58	hiredman	like the number 1
17:58	somnium	ngoc: to manage state you could (def felix (atom (cat "felix" "purple")))
17:59	ngoc	hiredman: felix now has a state
18:00	somnium	assuming felix may need to change his name to "fluffy" or his color to blue or something in the forseeable future
18:00	hiredman	ngoc: you mean with the atom?
18:00	hiredman	please be aware that I did not use an atom
18:01	ngoc	yeah, an id has a state has a value
18:01	hiredman	what id?
18:01	ngoc	felix
18:02	hiredman	an atom has state and its state is a function of its past state
18:02	hiredman	but I am not talking about atoms
18:03	hiredman	(defn cat [name color] {:name name :color color})
18:03	hiredman	no state
18:03	hiredman	{:name "bob" :color :white) is immutable
18:03	hiredman	er, \|
18:03	hiredman	}
18:04	chouser	technomancy: the problem is not new, I think.
18:05	chouser	(count (into [] (into #{} badseq))) ==> 6
18:05	chouser	(count (into #{} badseq)) ==> 2
18:05	ngoc	I know all about immutable because I come from Erlang. I just want to ask if I write cat.clj this way, it's just like using C to write program in OOP style. Is there a better way? A "Clojure way"
18:05	chouser	That's before the
18:05	technomancy	chouser: badseq is made up of method objects?
18:05	hiredman	ngoc: what style?
18:06	chouser	That's before the TransientSet stuff. That shouldn't be possible, right?
18:06	technomancy	sure doesn't seem like it
18:06	hiredman	I can assure you {:name "bob" :color :white} has very different properties from a struct in C
18:06	chouser	(count (seq (into #{} badseq))) ==> 6
18:07	technomancy	chouser: where did you get badseq?
18:08	chouser	technomancy: (def badseq (reduce into [] (map second MB)))
18:08	chouser	where MB is the value of mb from line 215 of proxy_core.clj
18:08	chouser	...when you run (proxy [java.io.StringWriter] [])
18:08	technomancy	gotcha
18:09	chouser	I've gotta go. If we can't figure this out this evening, I'll just roll back cgrand's patch until someone can fix it.
18:09	ngoc	hiredman: OOP style in C. You pass the immutable struct to functions to get another struct.
18:09	technomancy	OK, thanks for looking at it
18:10	hiredman	ngoc: that is functional style in C, OOP style is generally to mash all over the struct and return null
18:10	hiredman	pardon, NULL
18:10	somnium	I like that description of OOP
18:12	hiredman	actually, I guess it wouldn't have the return type void and just not returning anything, I dunno if that is semantically equivilant to returning NULL
18:13	somnium	usually you can at least get back a pointer to the struct you're abusing
18:13	hiredman	to really be safe you would need to do a deep copy of the struct
18:15	hiredman	I mean, any function can just traipse in and hose a string, since the string is just an exposed null terminated character array
18:15	hiredman	it's barbaric
18:15	funkenblatt	don't knock barbarians
18:15	funkenblatt	they conquered most of europe
18:16	funkenblatt	still wouldn't want to program with them though
18:16	ankou	hi, what exactly does the private key in the metadata of functions? Does it only affect javacode, or does it also prohibits access from other namespaces or what does it?
18:17	technomancy	funkenblatt: so no visigoth-driven-development for you?
18:18	funkenblatt	not unless it happens to be politically expedient at the time
18:18	hiredman	funkenblatt: yes, but the upper class of the barbarians were heavely influenced by rome and spent most of their time trying to legitimize their authority by expressing it in roman modes
18:19	technomancy	"upper class barbarians" is a funny concept.
18:20	hiredman	well, the ruling elites
18:20	funkenblatt	so i guess the lesson learned here is that C programmers will eventually adopt our ways after they've crushed us
18:20	hiredman	C programs already did crush us
18:21	hiredman	we are somewhere around 1300
18:22	funkenblatt	hmm... after they've crushed a few new uprisings
18:24	technomancy	(= (.hashCode (first badseq)) (.hashCode (second badseq))) ;; true
18:24	technomancy	(.contains (hash-set (take 1 badseq)) (second badseq)) ;; false
18:24	technomancy	that's a bug all right
18:41	rhickey	technomancy: inequal things can have the same hash code
18:41	chouser	all methods have the same hash code apparently. :-)
18:42	technomancy	chouser: well that would do it.
18:43	chouser	but (count theset) != (count (seq theset)) is clearly a bug, and apparently predates cgrand's patch
18:44	rhickey	Chouser: I'm dropping in late, where's the example?
18:44	chouser	it's hard to construct data that shows the problem. our only current example is proxy
18:45	chouser	in master (proxy [java.io.StringWriter] []) throws an exception
18:46	chouser	reverting cgrand's TransientHashSet patch "fixes" proxy, but I'm getting this weird set behavior even before his patch
18:47	rhickey	Chouser: I get: #<StringWriter$0 >
18:47	chouser	in latest master!?
18:47	chouser	technomancy and I are both seeing this.
18:48	chouser	churib: I think that's because of the proxy thing. Just back out the last few revs of clojure for now
18:49	rhickey	ok, I had 868f865bfc5445bea6d6092bc780f05ab0d23c21
18:49	technomancy	churib: using master and swank-clojure?
18:49	rhickey	must have been introduced since
18:49	technomancy	churib: or just clojure-mode by itself?
18:49	churib	chouser: yeah, will try that
18:49	churib	technomancy: nope, master and swank-clojure
18:50	technomancy	churib: master~4 is far enough back
18:50	churib	k, will give it a try - thanks!
18:50	chouser	,(let [badseq2 (concat (.getMethods java.io.StringWriter) (.getDeclaredMethods java.io.StringWriter)) badset2 (into #{} badseq2)] [(count badset2) (count (seq badset2))])
18:50	clojurebot	[26 26]
18:50	chouser	hmph. I'm getting [16 26] for that
18:51	rhickey	ok, I can reproduce it here
18:51	rhickey	I imagine it's the TransientSet patch?
18:51	technomancy	rhickey: that's what made proxy break, but this odd set behaviour predates it.
18:52	technomancy	chouser: not sure how often clojurebot updates
18:52	technomancy	I get [16 26] here
18:52	chouser	that's with 64323d8c6ad4962ac780d4d904b69a891ab312f8
18:53	technomancy	you don't need getDeclaredMethods
18:54	hiredman	not too often
18:57	technomancy	interesting that toString shows 26 elements
18:57	technomancy	(count (re-seq #"Method" (str badset2))) ;; <= 26
18:58	technomancy	while (count badset2) is 16
18:59	rhickey	this is a map bug, must be some other count maintenance issues with the new map code
19:00	technomancy	right, since APersistentSet passes off a lot of things to its impl
19:00	chouser	oh, indeed. I thought I had tests showing hash maps were ok
19:01	chouser	,(let [badseq2 (.getMethods java.io.StringWriter) badset2 (into {} (map vector badseq2 badseq2))] [(count badset2) (count (seq badset2))])
19:01	clojurebot	[26 26]
19:01	chouser	that's [16 24] here
19:14	technomancy	so transient maps have been around for a while; I guess this suggests that the count is broken there?
20:02	rhickey	fixed
20:02	rhickey	http://github.com/richhickey/clojure/commit/b4095306ddc59c1a992c39369f06f1315b97d377
20:03	technomancy	rhickey: awesome; thanks!
20:03	rhickey	np
20:04	rhickey	It would be good if cgrand gave it an audit as well
20:04	technomancy	those darn hash collisions...
20:09	rhickey	yeah, looks like reflect Methods have crappy hashes
20:09	rhickey	same name, same hash
20:11	rhickey	HashCollisionNode obviously wasn't getting much exercise otherwise
20:12	technomancy	pretty edge-casey, yeah
21:04	chouser	That would make for a very interesting screencast. 1 hour of rhickey hunting a bug
21:08	hiredman	I think it might have a limited audience
21:23	chouser	hm, perhaps
21:42	Makoryu	, (3 "pizza")
21:42	clojurebot	java.lang.ClassCastException: java.lang.Integer cannot be cast to clojure.lang.IFn
21:43	Makoryu	^ What's the idiomatic way to do this?
21:43	hiredman	do what?
21:44	hiredman	you are trying to call an Integer as a function
21:45	hiredman	Integers are not functions, incase that was not clea
21:45	hiredman	r
21:45	Makoryu	(:a {:a \a})
21:45	Makoryu	, (:a {:a \a})
21:45	clojurebot	\a
21:45	Makoryu	I was trying to do this :p
21:45	hiredman	,(ifn? :a)
21:45	clojurebot	true
21:45	hiredman	,(ifn? 3)
21:45	clojurebot	false
21:46	Makoryu	Let me be clear: What's the idiomatic way to get the nth item of an arbitrary sequence?
21:46	hiredman	,(doc nth)
21:46	clojurebot	"([coll index] [coll index not-found]); Returns the value at the index. get returns nil if index out of bounds, nth throws an exception unless not-found is supplied. nth also works for strings, Java arrays, regex Matchers and Lists, and, in O(n) time, for sequences."
21:46	Makoryu	..... oh. _>_
21:48	Makoryu	s/_>_/>_>/
22:10	churib	swank works also again
23:55	churib	is there a function that inserts elements at any position in vectors, with shifting next elements?
23:56	clojurebot	function is <Chouser> there is one class per fn, one instance of it per closure
23:59	churib	or are zippers the right way?