#clojure – 2010-01-16

2010-01-16

00:38	Apage43	mm.
00:39	Apage43	Niftily, calling .invoke on clojure function from within Velocity Template Engine just plain works.
01:47	ndimiduk	I'm working on some java interop. How do I specify as metadata that a function parameter should be of type Class[] ?
01:48	ndimiduk	(defn -init [#^Class[] types] ...) is roughly what i'd like to express
01:48	ndimiduk	or do constructor argument type lists go somewhere else?
01:50	qbg	Does an array of objects not work for you?
01:50	ndimiduk	i suppose it could
01:51	ndimiduk	that would make the class less clear for java consumers
01:54	ndimiduk	oh, i should clarify: this is extending a base class which has multiple constructors of single argument with differing types
01:55	ndimiduk	so i'd like the appropriate version of -init to be called based on which constructor is invoked
01:56	Apage43	ndimiduk: perhaps you'd do well to write some 'briding' classes in Java, since it sounds like you aren't exposing a terribly 'lispy' API anyhow.
01:57	ndimiduk	hmm
01:57	Apage43	*bridging
01:58	ndimiduk	right
02:00	ndimiduk	ah, gen-class says i should specify :constructors {}
02:00	ndimiduk	so would I say :constructors {[] [String] [Class<>]} ?
02:56	rikthevik	hey, i'm having trouble getting lein to run my tests
02:56	rikthevik	Caused by: java.lang.Exception: No such var: clojure.test/successful?
02:57	rikthevik	thoughts?
03:02	Jomyoot	How can I get stack trace to compojure
04:18	bagucode	Hello all
04:47	lypanov	damn, elpa isn't the most reliable thing ever...
05:06	lypanov	how do i get a pretty print out of the available methods for a given namespace?
05:07	lypanov	(doc *) is neat but i'd expect (doc ns) to work actaully. and for it to pretty print the first line of each doc for the ns-publics result
05:07	clojurebot	"([] [x] [x y] [x y & more]); Returns the product of nums. (*) returns 1."
05:07	lypanov	heh
06:01	dabd	are there any guidelines for writing clojure doc strings?
06:01	dabd	for when someone writes clojuredoc...
11:48	michael___	I went to a great presentation by Michael Fogus on Clojure 1.1 and 1.2 features.
11:50	michael___	I'd like to dive into some of them, especially the new concurrency constructs like futures and promises. I'd also like to explore reify deftype and defprotocol.
11:50	michael___	I'm blanking on good applications for small projects, though.
11:51	michael___	Any suggestions? I'd like to do something a little involved and practical, to apply these new features
11:51	michael___	We would have loved to have you there, chouser
11:52	chouser	hm, practical and small is a hard combination.
11:52	michael___	I've looked at your Project Euler solutions in the past
11:53	michael___	I don't know if Euler is a good source for this, tho
11:53	chouser	michael___: A nice thought. Half a continent away though. :-/
11:54	michael___	chouser: at least we know how to pronounce your name, now, thanks to fogus
11:54	chouser	for deftype all you need is to think of some new structure that you want to play nicely with clojure's builtin fns like seq
11:54	michael___	good point
11:55	michael___	Is anyone using these features in their work or own projects right now?
11:57	chouser	perhaps nobody who is here on saturdays :-)
11:58	michael___	LOL
11:58	michael___	I'll think about it some more and ask Google some more. Thanks!
12:08	dabd	when u need to bind a variable 'foo' which is based on another similar variable, do you consider good style to give it the same name or is it better something like foo2
12:09	dabd	example (defn f [foo] (let [foo2 (some-fn foo)] (println foo2)))
12:09	chouser	dabd: It's a bit of a judgement call of course, but it's not always bad to reuse the same name.
12:10	chouser	I guess I'd say there's no much point in sticking a 2 on there if that's the best new name you can com up with. :-)
12:10	dabd	i tend to append an asterisk to the original name but it can be confusing and error prone
12:10	qbg	If the shadowing doesn't affect me, I reuse the name
12:10	qbg	(assuming the original name still makes sense)
12:17	lypanov	whats the best way to connect to a mysql db with clojure?
12:17	lypanov	its for data extraction, no writing.
12:17	lypanov	need a batch access method therefore.
12:19	tolstoy	lypanov: Can you just shell out to the mysql client?
12:20	tolstoy	(Assuming you don't want to use the contrib.sql / jdbc stuff.)
12:20	lypanov	contrib.sql is an option, i just can't find others with a quick google :)
12:21	tolstoy	I think there's a ClojureQL.
12:21	lypanov	ah, thats the one. thx! reading up on it
12:23	dabd	sometimes I think it would be nicer to have only parenthesis as the delimiters and read macros for vectors #V, maps #M, sets #S, and so on. Does anyone agree?
12:24	dabd	OTOH for readability Clojure syntax is great. The single delimiter syntax would make code editing slightly easier IMHO
12:25	dabd	I used Common Lisp for some time so I'm a suspect...
12:25	tolstoy	I think of [ and { as '( and find it's easy to get away with thinking like that most of the time.
12:25	chouser	dabd: you'd really want (let #V(a 10 b 20) (+ a b)) ?
12:26	chouser	tolstoy: beware that '
12:26	chouser	[ and { are semantically a bit closer to (list I think
12:27	tolstoy	I guess that's sorta what I was thinking, but yeah, you're right. Obviously, I use clojure pretty simply.
12:28	dabd	chouser: like I said I used Common Lisp for some time. For instance when ending a function definition in CL I just closed all parenthesis in row on the same line. However with clojure because we have different delimiters I feel the need to close them 'a la' Java.
12:29	rikthevik	has anyone here got experience with "lein test"?
12:29	dabd	each one on a different line so they don't appear all mixed up on the same line
12:29	rikthevik	No such var: clojure.test/successful?
12:29	chouser	dabd: it's a point that's been mae before, though that's the first I've seen your #V suggestion.
12:29	chouser	been made
12:30	chouser	but please don't put your closing parens on different lines! :-)
12:32	dabd	chouser: if I have several ) in a row I don't put them on the same line but if a } or ] I think it looks ugly to close them all on the same line )))]})))) like this
12:33	dabd	chouser: the #V is clearly stolen from Lisp and I'm sure Rich Hickey thought about this when creating clojure and it's syntax
12:34	dabd	chouser: I will follow the conventions and close them on the same line though!
12:38	tolstoy	dabd: Wasn't part of the goal with clojure to appeal a little to users of other dynamic languages?
12:39	tolstoy	So you get brackets for arrays, braces for maps, commas....
12:43	stuartsierra	In Clojure 1.0, conj on a vector does not preserve metadata. Is that a bug?
12:43	stuartsierra	In Clojure 1.1, conj on vectors does preserve metadata.
12:44	dabd	tolstoy: sure it was
12:45	alec	how can I check if an item is in a list?
12:46	stuartsierra	,(some #{:a} (list :b :a :c))
12:46	clojurebot	:a
12:47	stuartsierra	,((set (list :b :a :c)) :a)
12:47	clojurebot	:a
12:48	alec	stuartsierra: hm, ok. I also just stumbled upon (.contains (list :a :b) :a), which seems to work
12:49	stuartsierra	alec: In general, if you're testing whether or not a list includes something, consider using a set instead of a list.
12:50	aldebrn	Can I experiment with clojurebot in a test channel? I want to see if I can ask the humans a question with a case example
12:50	aldebrn	Ah, I can message it directly
12:53	lypanov	ouch. search doesn't show all matches on clojars.org.
12:56	lypanov	is there any way to get emacs to make its current state a bit more obvious?
12:56	lypanov	frequently i end up getting lost in weird modes
12:56	the-kenny	lypanov: The modes are shown in the info bar
12:56	the-kenny	lypanov: And you can cancel almost everything with Esc Esc Esc
12:56	the-kenny	(Or C-g)
12:57	lypanov	ah, finally. thank you!
12:57	lypanov	no... it did it again. vi-mode just randomly ending. !@#@$%
12:58	the-kenny	I don't have any experience with vi-mode, sorry
13:00	aldebrn	,(for [val '(1 2 3 4 5)] (let [big-enough? #(> %1 val)] (big-enough? 3)))
13:00	clojurebot	(true true false false false)
13:00	aldebrn	Why does that no work if instead of (big-enough? 3) there I called another function that used big-enough? ?
13:01	Chousuke	hm?
13:02	aldebrn	So if I had (foo 3) instead of (big-enough? 3) there, and I had previously defined (defn foo [x] (big-enough? x)) and (defn big-enough? [x] (> x 0)), calling that "for" comprehension would use this latter definition of big-enough?
13:03	aldebrn	Instead of the new big-enough?'s I was defining in the let
13:03	alec	stuartsierra: thanks, that actually made the problem a lot easier. I did't even need to do that check.
13:04	lypanov	the-kenny: i found out why... thought vip-mode == vi-mode
13:04	ben_m	Could anyone who uses Clojure with Emacs/Slime give me a sample .emacs? I just can't get it to work :(
13:05	Chousuke	aldebrn: let bindings are lexical, not dynamic
13:07	lisppaste8	qbg pasted "My .emacs" at http://paste.lisp.org/display/93500
13:07	the-kenny	ben_m: I suggest using elpa.
13:07	qbg	Has stuff you probably don't need
13:07	the-kenny	It's a no-brainer then
13:08	qbg	elpa helps
13:08	ben_m	hmm
13:08	aldebrn	Chousuke, thanks. So the functions I call from a let's expression will not be aware of let rebinding sub-functions that they will use
13:08	ben_m	qbg: thanks
13:08	qbg	I used to use ELPA, but now I manage my own copies
13:09	tolstoy	Does elpa have a mechanism for detecting and then applying updates to packages?
13:09	the-kenny	tolstoy: I modified slime.el and it detected my changes and asked me to recompile it
13:11	Chousuke	aldebrn: yeah. for that, you need the binding macro
13:11	tolstoy	the-kenny: So that solves the case of detecting that there's been an update to clojure-mode, or paredit, etc?
13:11	tolstoy	the-kenny: Not local update, but a new package up at the elpa site?
13:11	the-kenny	tolstoy: No, I don't know if it does that.. sorry
13:12	qbg	I think package-list-packages will fetch the new list from the server
13:12	qbg	(or there is another command)
13:12	tolstoy	elpa faq isn't helping....
13:12	Chousuke	aldebrn: note, though, that binding only affects code that actually executes within the binding block. thus, laziness is a caveat
13:12	qbg	Then you can select to install the new packages
13:13	tolstoy	qbg: If you've already installed a package, once you refresh, does it let you know there's a new version?
13:13	qbg	The old version is listed as obsolete and the new version is in the list
13:14	tolstoy	qbg: Ah, cool. I note that their front page says "upgrade". ;)
13:15	ben_m	baaah
13:15	ben_m	It won't work!
13:15	tolstoy	Ah, I see two versions of erc (for instance). Interesting.
13:16	qbg	ben_m: What are you getting?
13:16	ben_m	Polling "/tmp/slime...." (abort with ...)
13:16	ben_m	forever though
13:16	ben_m	I don't get the CL-USER> prompt like I do with sbcl :(
13:17	qbg	What do you see in inferior-lisp?
13:18	ben_m	The clojure repl
13:18	ben_m	ah
13:18	ben_m	user=> java.io.FileNotFoundException: Could not locate swank/swank__init.class or swank/swank.clj on classpath: (NO_SOURCE_FILE:0)
13:18	robwolfe	ben_m: do you have "require 'slime" after elpa package.el is loaded?
13:18	ben_m	I don't use elpa
13:18	ben_m	But I do require slime
13:19	qbg	Where is your swank-clojure?
13:19	ben_m	The dir?
13:19	qbg	The jar
13:19	qbg	It needs to be on the classpath
13:19	ben_m	I don't have that jar I think
13:19	qbg	Did get swank-clojure from git?
13:20	ben_m	yeah
13:20	qbg	Do you have leiningen installed?
13:20	ben_m	leiningen?
13:20	clojurebot	leiningen is a build tool designed not to set your hair on fire (http://github.com/technomancy/leiningen)
13:20	ben_m	I do not
13:20	qbg	Once you have it, do `lein jar` in the directory
13:20	qbg	That will build the jar for you
13:20	ben_m	Oh
13:21	qbg	Luckily leiningen is easy to install
13:21	rikthevik	I'm getting this error with "lein test". No such var: clojure.test/successful?
13:21	rikthevik	thoughts?
13:21	LauJensen	Gents I'm doing an experiment for which I need some help. Has anyone here got access to a public MS Sql databases which I can try to log into, run a select now(); and drop out again ?
13:22	ben_m	So leiningen is ant without the XML?
13:22	qbg	Or something
13:22	rikthevik	ben_m: and maven without the brain damage
13:22	qbg	(makes me think of ASDF)
13:22	ben_m	nice
13:23	ben_m	I'm no fan of Java tbh, classpath makes me weep :D
13:24	ben_m	qbg: Do I need swank.jar?
13:24	qbg	Something like that
13:24	the-kenny	swank-clojure.jar
13:25	ben_m	hmm
13:25	qbg	Actually, once you have it built, you can test it before altering your .emacs
13:25	lypanov	ben_m: classpath itself is a brillian idea. but tooling it is hard.
13:25	ben_m	No idea where to run lein jar
13:25	the-kenny	leiningen manages all classpath stuff for me :)
13:25	ben_m	There's no project.clj anywhere
13:25	lypanov	lein help new
13:26	qbg	From whose repo did you clone swank-clojure?
13:26	ben_m	Uh, can't remember :\|
13:26	ben_m	Whose should I clone it from?
13:26	lypanov	hope it wasn't the first google hit...
13:26	ben_m	It might have been.
13:26	lypanov	(the mistake i made last night)
13:26	lypanov	ben_m: technomancy.
13:26	ben_m	Oh
13:26	lypanov	i used the first google hit, it breaks completely.
13:26	ben_m	I cloned it from joshua or something like that, I think.
13:27	lypanov	jochu.
13:27	qbg	Yeah, that is old
13:27	lypanov	yeah... made the same mistake.
13:27	ben_m	:/
13:27	lypanov	ben_m: you would have heard me say the same thing last night :P
13:27	qbg	ben_m: Some pain now, fun later ;)
13:27	lypanov	took me a bit longer to realize though.
13:28	lypanov	ben_m: technomancy for clojure-mode etc also.
13:28	lypanov	technomancy kept telling me last night to read the "clojure-mode readme. it explains everything"
13:28	lypanov	after 2 hours i realized i was reading the wrong readme...
13:28	qbg	lol
13:28	ben_m	hah
13:30	dabd	why the naming inconsistency empty? vs. not-empty (one ends with ? and the other not)?
13:30	LauJensen	Functions ending with ? are predicates returning true/false, not-empty is not one such
13:31	the-kenny	not-empty returns nil or a coll
13:31	the-kenny	Not a boolean
13:31	dabd	ok. thanks
13:34	ben_m	Maybe I should check out ELPA
13:34	LauJensen	why the sigh ?
15:26	qbg	Is this view of clojure correct? http://vintage-digital.com/hefner/misc/lisp-programmers.jpg
15:27	defn	i dont think so
15:28	defn	PHP is dead on though
15:28	qbg	If Clojure is the Borg, who wouldn't want to be part of the Borg?
15:28	defn	me, because of the assimilation mostly
15:29	hiredman	http://www.loper-os.org/?p=42
15:29	qbg	Scotty is elisp?
15:29	qbg	I guess I can see that
15:30	hiredman	I think you a missing the fact that it is supposed to be from the perspective of a common lisp programmer
15:30	lypanov	i think i want to learn asp.net.
15:30	lypanov	and make friends.
15:31	defn	yes! making friends!
15:31	defn	i remember that!
15:31	qbg	WE SHALL ASSIMILATE YOUR FRIENDS
15:33	defn	qbg: :(
15:33	qbg	RESISTANCE IS FUTILE
15:39	somnium	alexyk: ping
15:40	bpsm	ain't nobody here but us chickens
15:40	ben_m	LauJensen: Mind linking your screencast again? I got distracted before.
15:41	LauJensen	Sure - but I'm moving the server from the US to London as we speak
15:41	LauJensen	I'll let you know when I'm done
15:41	ben_m	alright :)
15:48	LauJensen	ben_m: Looks like it'll be about 50 minutes
15:49	lpetit	Hello
15:49	ben_m	LauJensen: Alright, I'll try it on my own in the meantime :)
15:49	lpetit	Who wants to take the task of hosting clojure with Go ? ! :-) http://www.infoq.com/articles/google-go-primer
15:52	bagucode	lpetit: Making the data structures and reader should be straight forward enough. But then there is the issue of compilation. The ASM library and the classloaders provides that for the jvm. What would you use with Go? LLVM would be my choice I guess.
15:53	chouser	why not just generate golang source?
15:53	lpetit	What is LLVM ?
15:53	chouser	it worked well enough for javascript, seems likely it would work for golang
15:54	lpetit	chouser: how do you get, then the dynamicity of a REPL ?
15:54	chouser	oh. well. they claim their compiler is fast, right? :-)
15:55	lpetit	:)
15:55	bagucode	LLVM is a bunch of stuff. It's a portable assembly language with associated tools for optimization and compilation. It's pretty cool stuff actually. Since the compilation infrastructure is all libraries you can use it as a JIT compiler as well.
15:55	chouser	generate sources, compile to a .so, ldload, run
15:55	chouser	:-)
15:56	bagucode	LLVM is much cooler, no offline or source generation needed.
15:56	lpetit	chouser: in which state is "clojure hosted on javascript" (don't know the exact name), btw ?
15:56	bagucode	It's like ASM + classloader, but for native code
15:56	lpetit	bagucode: looks very interesting !
15:56	bagucode	But ... what would be the point of implementing clojure on top of Go? Hotspot is already very fast actually. Memory consumption maybe?
15:57	chouser	lpetit: clojurescript. a significant subset of clojure was working, but because lots of parts had to be hand-translated, clojure has moved on and clojurescript has been left behind
15:57	lpetit	chouser: do you consider reactivating the project once cinc has become a reality ?
15:57	chouser	absolutely
15:58	lpetit	wonderful! Oh, I would need it by monday, if possible.
15:58	lpetit	I once had the idea of calling the eclipse plugin for clojure : "Ectoplasm".
15:59	lpetit	I guess when cinc has become a reality, this name could pretty well describe the phenomenon : clojure the ectoplasm attacking each and every platform which already has a story for gc and threading ! :)
16:00	chouser	hm, I'd rather it not be so restrictive.
16:00	chouser	though maybe it's obvious to people who know gc better than I that simple reference counting won't cut it.
16:01	bagucode	Well, it's certainly much less work to not have to do the GC :)
16:02	lpetit	yeah, even if doable in practice, I guess no gc would be a blocker for most people
16:02	lpetit	s/in practice/in theory/
16:03	bagucode	I think Apple actually open sourced their multithreaded Objective-C GC. I think it's written in C or C++ so it's usable by pretty much any language implementation.
16:03	bagucode	I looked at it briefly but couldn't find much documentation
16:03	bagucode	:(
16:04	chouser	how would llvm interact with golang?
16:04	bagucode	llvm has a C interface so just call that from Go
16:05	bagucode	It has functions for instruction generation sort of like ASM does
16:05	bagucode	Then you say something like ExecutionEngine.getFunction(blah blah) and you get a pointer to you new native-compiled function
16:06	ben_m	Woo
16:06	bagucode	I have actually used LLVM from Clojure ;) I'm crazy that way.
16:06	ben_m	LauJensen: nevermind!
16:07	ben_m	I used ELPA and let it install clojure, works now :)
16:07	LauJensen	k
16:07	jevgeni	hi guys. I tried (+ 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1) with resulted in 0.9999999999999999. I know this is a very old Java problem, but what was the reason it was not fixed in Clojure (compared to Groovy/Scala)?
16:10	bagucode	chouser: I don't know if you remember but I said that one of my motivations for clj-native was that I wanted to use a C library with a large amount of small functions. That was LLVM, I was playing around with it at the time. Both the C and C++ interfaces for it are horrible and I thought that if I could use it from Clojure I could make some sort of assembler dsl that would make it more pleasant :)
16:12	gregh	jevgeni: there's nothing to "fix", that's how computers do arithmetic
16:12	gregh	the reason is that 0.1, although it looks nice and round in decimal, can't be represented exactly in a binary fraction
16:13	ben_m	The "fix" is to use a library
16:13	Chousuke	,(+ 0.1M 0.1M 0.1M 0.1M 0.1M 0.1M 0.1M 0.1M 0.1M 0.1M)
16:13	clojurebot	1.0M
16:13	Chousuke	Bigdecimals :P
16:13	gregh	an excellent article on the topic is: http://docs.sun.com/source/806-3568/ncg_goldberg.html (What Every Computer Scientist Should Know About Floating-Point Arithmetic)
16:13	ben_m	:D
16:13	qbg	You could also use rationals
16:14	qbg	,(+ 1/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10)
16:14	clojurebot	1
16:14	Chousuke	hmm
16:14	Chousuke	,(+ 1 1/10
16:14	clojurebot	EOF while reading
16:14	jevgeni	gregh: yes, I know this. however, you don't save 0.1M or 1/10 in databases. I am worried about the integration with the exising datasources and performing operations on these values.
16:14	Chousuke	,(+ 1 1/10)
16:14	clojurebot	11/10
16:15	Chousuke	jevgeni: There's nothing Clojure can do about Java's Doubles :/
16:15	gregh	a common way to avoid the problem in situations such as financial calculations, is to store all values in integer numbers of cents instead of dollars (for example) and do all integer calculations
16:16	jevgeni	theoretically, can I redefine the + to represent 0.1 as bigdecimals?
16:16	Chousuke	just use 0.1M
16:16	gregh	or integer numbers of tents of cents if you want to handle rounding yourself
16:16	Chousuke	This only applies to literals anyway.
16:16	Chousuke	if you get a double from some API, then you have to deal with the imprecision
16:16	Chousuke	there's no way around it
16:17	Chousuke	You need to complain to the API creators to make one that gives you BigDecimals :P
16:17	hiredman	jevgeni: why don't you have 0.1M or 1/10 in databases?
16:18	jevgeni	hiredman: it's already saved as float number. a big legacy system to integrate)
16:18	hiredman	well
16:19	hiredman	you are screwed if you are already using floats
16:19	hiredman	and have been since the beginning
16:19	bagucode	jevgeni: so convert the numbers to rationals or bigdecimals when getting them from the DB then and at least the errors won't compound more?
16:20	bagucode	,(rationalize 0.1)
16:20	clojurebot	1/10
16:20	hiredman	it's the kind of error there isn't any recovering from
16:20	jevgeni	bagucode: thanks for hint
16:21	Chousuke	hmm
16:21	hiredman	you can't tunnel to the past and make things precise
16:21	Chousuke	,(rationalize 0.18923893)
16:21	clojurebot	18923893/100000000
16:21	gregh	,(rationalize (+ 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1))
16:21	clojurebot	9999999999999999/10000000000000000
16:21	bagucode	:D
16:22	bagucode	,(reduce + (map rationalize [0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1]))
16:22	clojurebot	1
16:23	jevgeni	(class (+ 1.5M 1.5))
16:23	jevgeni	,(class (+ 1.5M 1.5))
16:23	clojurebot	java.lang.Double
16:24	jevgeni	(class (+ 15/10 1.5))
16:24	jevgeni	,(class (+ 15/10 1.5))
16:24	clojurebot	java.lang.Double
16:24	alec	can a java array returned by something like String.split be converted into a clojure list?
16:24	lpetit	,(apply + (map rationalize [0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1]))
16:24	clojurebot	1
16:25	lpetit	alec: sure
16:26	lpetit	,(into () (.split "hello you" " "))
16:26	clojurebot	("you" "hello")
16:26	lpetit	,(type (into () (.split "hello you" " ")))
16:26	clojurebot	clojure.lang.PersistentList
16:26	alec	lpetit: ah, cool. thx
16:26	lpetit	you would rather prefer putting it in a vector, though, to preserve the array order :
16:26	lpetit	> ,(type (into [] (.split "hello you" " ")))
16:26	lpetit	,(type (into [] (.split "hello you" " ")))
16:26	clojurebot	clojure.lang.PersistentVector
16:27	lpetit	,(into [] (.split "hello you" " "))
16:27	clojurebot	["hello" "you"]
16:27	lpetit	alec: vectors preserve the constant time access to their contents by index. accessing lists by index is done in linear time.
16:28	lpetit	,(doc list)
16:28	clojurebot	"([& items]); Creates a new list containing the items."
16:28	lpetit	,(doc nth)
16:28	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."
16:28	qbg	,(vec (.split "hello you" " "))
16:28	clojurebot	["hello" "you"]
16:28	Chousuke	of course, if you don't need a vector:
16:28	Chousuke	,(seq (.split "hello you" " "))
16:28	clojurebot	("hello" "you")
16:29	lpetit	Chousuke: :is it "cheaper" in terms of memory or cpu to use seq instead of vec (assuming you want to consume the whole thing) ?
16:32	bagucode	Good question. Without looking at the source I think that's hard to answer. The seq from the array is a wrapper object right? So that introduces some overhead. The vector is a little heavier object than the array, but on the other hand it is it's own sequence, so it shouldn't add any overhead to call seq on it? I'm just speculating I haven't looked at the implementation so don't listen to me :)
16:35	Chousuke	lpetit: Hm.
16:35	Chousuke	lpetit: vec needs to copy the array, so I think it's slower
16:36	Chousuke	though it might be that vec just assumes ownership of it and "lazily" wraps it in a PersistentVector-like interface
16:36	Chousuke	but I guess seq would be faster
16:37	lpetit	Well, one also has to consider that alec wants to wrap an array. So depending on his use case, snapshotting the array content into a vector may be safer than relying on the array never changing and just having a seq over it
16:37	lpetit	I also guess that seq over an array only has to store a ref to the array and an index, so yes, certainly much cheaper
16:38	lpetit	But anyway, wouldn't the array work "as is" with most core functions working on seq, since they call (seq) on their arg, don't they N
16:38	lpetit	?
16:38	Chousuke	yeah
16:38	LauJensen	bestinclass.dk is back up again, now serving from London
16:38	Chousuke	I had some adventures with my brand new QNAP NAS today
16:39	Chousuke	I managed to brick my Debian installation on it. had to set up a dhcp/tftp server and restore from a backup firmware image ;/
16:40	Chousuke	Good thing I didn't have to resort to using a serial console, though.
16:41	Chousuke	rebooting things accessible only via the network is rather... stressful
16:47	LauJensen	Yes sir
16:47	bagucode	LauJensen: I just scrolled through your blog archive and saw this "An official from Reddit has asked that sleeps be inserted into the code..." did they get hammered after that article?
16:47	LauJensen	I think so
16:48	LauJensen	I saw a comment on HN saying that they got a traffic boom
16:48	bagucode	Guess you have a lot of readers :)
16:48	LauJensen	Yes - I'm glad I started with a low entry bar, because it means that people not actually read the code, but they feel comfortable enough with it to download and play with it - thats pretty great considering this is Clojure and not some mainstream language
16:50	LauJensen	eh, rephrase "not actually read" = "not just read"
16:51	jevgeni	,(* 100M 1.1)
16:51	clojurebot	110.00000000000001
16:51	jevgeni	shouldn't 1.1 be converted to bigDecimal instead on BigDecimal converted to Double?
16:51	jevgeni	instead of*
16:52	alec	how can I combine two sets, ie, #(1 2 3} and #(4 5 6} go to #{1 2 3 4 5 6}
16:53	Chousuke	,(into #{2 3 4} #{5 6 7})
16:53	clojurebot	#{2 3 4 5 6 7}
16:53	alec	Chousuke: ha, same function that answered my last question... thx
16:53	Chousuke	there's also clojure.set/union I guess
16:54	Chousuke	~def clojure.set/union
17:23	dabd	is there a function that iterates each successive tail of a seq?
17:24	patrickdlogan	who's got the most current, accurate instructions for setting up slime / swank?
17:24	patrickdlogan	tried clojure-install in emacs - it said deprecated in favor of swank-clojure
17:24	esbena	patrickdlogan: use swank-clojure instead
17:25	dabd	I defined this trivial function to do it http://pastebin.com/m105bb8a8
17:26	patrickdlogan	esbena: yeah, went to swank-clojure and the README is still from May and says "step 2. invoke m-x clojure-install..."
17:26	patrickdlogan	esbena: so I should ignore the README?
17:27	esbena	patrickdlogan: I'm pretty sure I just used the installer in Emacs. Then it worked out of the box
17:39	chouser	,(take-while seq (iterate rest [1 2 3 4]))
17:39	clojurebot	([1 2 3 4] (2 3 4) (3 4) (4))
17:39	chouser	when did not-empty show up??
17:40	chouser	huh. it's old. :-/
17:42	dabd	chouser: take-while returns the sequence of tails. I just want to iterate them. perhaps I should wrap it in a dorun?
17:45	chouser	dorun also just returns them. what do you mean by "iterate them"
17:46	dabd	do something with each tail but not collect them
17:46	kotarak	dabd: doseq
17:46	dabd	what about this (defn do-tails [s f] (doseq [item (take-while seq (iterate rest s))] (f item)))
17:47	kotarak	dabd: that's just (doseq [item s] (f item))
17:48	kotarak	dabd: ah no. it is not. Forget what I said
17:48	dabd	kotarak: yes I didn't name item properly it should be named tail
17:48	lpetit	,(doc recursions)
17:48	clojurebot	Pardon?
17:48	lpetit	clojurebot: nevermind
17:51	Raynes	chouser: What are you guys using to write your book?
17:59	chouser	Raynes: knowledge we've gained through decades of research and hard work
17:59	chouser	:-)
17:59	Raynes	chouser: Heh heh.
17:59	Raynes	I meant that rather literally.
17:59	Raynes	:p
17:59	chouser	I'm mostly using vim. I believe fogus mostly uses emacs.
18:00	Raynes	I tried to use muse mode, but it doesn't seem to work right for me. :\
18:00	Raynes	It looked awesome too.
18:00	Raynes	Shame.
18:01	chouser	some of the first stuff was written in etherpad
18:02	Raynes	Using LaTeX or something?
18:03	chouser	Manning has a docbook-like xml format they like, and tools to generate pdfs as well as whatever they need to actually go to print.
18:03	Raynes	I see.
18:03	Raynes	I'm clueless about book writing. :\
18:04	chouser	so we've developed a tool that converts a somewhat extended version of Markdown to Manning's XML format.
18:05	chouser	I was too! Apparently a lot of their books are written and prepared in MS Word.
18:05	Raynes	I've read up on some OOo stuff about book writing. Styling makes my eyes water. It all seems too complicated.
18:07	Raynes	Muse-mode's documentation is thorough, but awful vague.
18:08	lpetit	dabd: your initial attempt was good too by not creating unnecessary sequences. I've just updated it to take into account that you want to eagerly consume it (so using next instead of rest), and getting rid of the loop to leverage the direct use of recur on the function: http://pastebin.com/m2725cd2d
18:10	lpetit	dabd: though now that I think about it, keeping your initial version, replacing the initialization of s in the loop (loop [s s]) by (seq s) : (loop [s (seq s)]), and then replacing rest with next should do it. (will save the superfluous call to seq, which is unnecessary but for the initialization of s arg)
18:15	dabd	lpetit: I don't understand the difference between your 1st 2nd suggestions http://pastebin.com/m28155e0c
18:15	mkh	chouser: i bought your book yesterday, any chance of it being published in ePub format
18:16	maacl	I would like to create a function that returns a unique pseudo random length vector of pseudo random ints. A max length of the vector and max value of the ints should be definable. Any hints?
18:16	lpetit	dabd: in the second, (seq s) will be called just once, at loop initialization. in the first, it is called every time
18:18	dabd	lpetit: of course. thx
18:19	Chousuke	,(vec (take (rand-int 10) (repeatedly #(rand-int 20))))
18:19	clojurebot	[14 12 0 2 2 14 8 13 13]
18:20	Chousuke	maacl: see above
18:20	dabd	lpetit: in practice this elegant functional version is very inefficient: both iterate and seq create sequences unnecessarily http://pastebin.com/m64eeb50b
18:21	maacl	Chousuke: thanks, but my challenge is the unique part, I am guessing a closure is the solution, but I cannot get my head around it
18:22	Chousuke	maacl: hmhm
18:22	Chousuke	maacl: you need to store the vectors in a ref I guess.
18:22	lpetit	dabd: yes, you only want side effects, and you know you want to go through the whole list eagerly, so you don't care about lazy seqs, you just want to iterate as quickly as possible. That's why I was considering that your initial attemp was more suited for defining such a general tool
18:23	qbg	maacl: A random length subseq of a permutation of 0 to n-1?
18:25	maacl	qbg: yes I believe so
18:25	qbg	If you define shuffle, the definition should be trivial
18:26	qbg	Something like (take (rand-int <num>) (shuffle (range <num>)))
18:28	maacl	qhg: so e.g. I have 5 vectors with 20 unique values in each and I want 10 unique vectors with a value from 1 to 5 of the vectors
18:28	dabd	lpetit: why is it necessary to call (seq s)?
18:29	qbg	The 10 vectors are of random length?
18:30	lpetit	dabd: (seq s) will ensure s is transformed into a seq, and also if s is an empty coll or an empty lazy seq, the result of calling seq is guaranteed to be nil. (remember that '() is not considered as logical false in clojure)
18:31	maacl	qbg: yes
18:32	qbg	Are the sets of values in the 5 vectors disjoint from each other?
18:32	maacl	it is like a cartesian product except not one item from each set but a random number of items with a max = the number of sets
18:32	dabd	lpetit: can u show me an example where this would not work correctly? http://pastebin.com/m5c4aa68f
18:33	chouser	mkh: I'll ask
18:33	mkh	chouser: thanks
18:34	qbg	Would taking items randomly from the concatenation of all 5 vectors work?
18:34	lpetit	dabd: hey, it will work correctly, not-empty is based on calling seq, look:
18:34	lpetit	~source not-empty
18:36	maacl	qbg: nope, if there is just one element in the vector it has to be from the first
18:36	maacl	qbg: the first set that is
18:36	dabd	lpetit: ok. thx
18:36	lpetit	dabd: but you're calling it every time, even so calling next in recur guarantees that you will either have a logical true, either nil (which is logical false), so there is just the initialization of the loop where u need to call (seq s) to ensure you have a correct logical false (nil) if s is empty
18:36	qbg	And if there are two elements in the vector?
18:37	maacl	qbg: they have to be from the first and second set
18:38	maacl	qbg: ah, i could just do the different relevant products and join them
18:39	qbg	If that works, why not
18:40	dabd	lpetit: this is getting slightly confusing. why should I worry about logical values if not-empty returns nil for an empty collection or the collection otherwise?
18:41	alexyk	can you nest a defn, you have to do an fn?
18:41	alexyk	or have to do an fn instead
18:42	qbg	Why would you want nest a defn?
18:42	patrickdlogan	trying to connect the dots between ELPA and github for swank-clojure...
18:42	lpetit	dabd: my point was not about using seq directly or using not-empty (this is basically the same thing), but about the fact that calling them is only needed once, since calling next will ensure that you either have an non empty lazy seq, or nil
18:42	lpetit	alexyk: ??
18:42	patrickdlogan	ELPA installed 1.1.0 of swank-clojure...
18:43	alexyk	hm, lots of FP is done with auxiliary functions, e.g. carrying an accumulator
18:43	patrickdlogan	github shows just one branch, 1.0
18:43	alexyk	the aux is only needed in the parent
18:43	alexyk	and hence good to nest and hide
18:43	qbg	You could use let/letfn
18:44	qbg	nested functions are good, but defn makes a global binding
18:45	hiredman	alexyk: def operates in the global scope
18:45	alexyk	hiredman: ok
18:45	hiredman	and local bindings of names are immutable
18:45	hiredman	so having def operate locally would be just weird
18:46	hiredman	so use let or letfn
18:47	qbg	Just be careful that you don't do unbounded recursion.
18:51	dabd	lpetit: got it. I had to look at the implementations of not-empty and next and finally figured what u meant. So u need to pay attention to which functions use seq under the hood when looping
18:52	dabd	so this is the final version: http://pastebin.com/m4926bb67
18:52	lpetit	dabd: it's in the public API/contract of 'next and 'seq to return nil on empty colls/lazy sequences.
18:53	lpetit	dabd: sure. going to bed now, cu
18:54	dabd	lpetit: thx
19:01	tolstoy	Anyone here using netbeans/enclojure?
19:03	tolstoy	Doesn't seem to want to install the plugin in netbeans 6.8. Surely, 6.8 is compatible....
19:07	tolstoy	Ah, has something to do with github downloading.
20:00	ajuc	hello, anybody compiled lately penumbra with leiningen
21:31	mebaran151	is there an easy way to turn a clojure hashmap into xml?
21:32	chouser	hm... recursively?
21:34	mebaran151	yeah
21:34	mebaran151	like the way we have write json
21:34	hiredman	mebaran151: like a clojure.xml hashmap?
21:34	mebaran151	I have a hash-map: I'd like to just output it to a flash client
21:34	mebaran151	thought xml would be the easiest way to do it
21:35	mebaran151	it seems like clojure.xml would have something like what I need but I haven't found it yet
21:35	hiredman	json is most likely the easiest way to do it
21:35	hiredman	clojure.xml has emit
21:35	chouser	I don't know of a generic map-to-xml, though it wouldn't be too hard to make.
21:35	hiredman	but you can;t use it on an arbitrary hashmap
21:36	mebaran151	hiredman: what kind of hashmaps can I use it on?
21:36	hiredman	the kind of hashmaps clojure.xml/parse produces
21:37	hiredman	flash is more or less javascript, why not use json?
21:37	mebaran151	I haven't been using contrib, and I thought maybe the xml ns had what I needed
21:38	mebaran151	also e4x makes these documents a little easier to work with
21:38	hiredman	you can just use clojure-json if you don't want to use contrib
21:38	mebaran151	extra lib though?
21:39	hiredman	yes
21:39	mebaran151	I should just probably use json-str in contrib
21:58	ben_m	,pastebin
21:58	clojurebot	java.lang.Exception: Unable to resolve symbol: pastebin in this context
21:58	ben_m	?pastebin
21:59	ben_m	Hmm
21:59	ben_m	Will just use a generic one ..
21:59	chouser	lisppaste8: url?
21:59	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
21:59	ben_m	http://sprunge.us/jRCW
22:00	ben_m	I'm trying to follow a tutorial ...
22:00	ben_m	Compiling this gives no errors, but when I run it, I only get an empty window :/
22:02	hiredman	what window manager?
22:03	hiredman	I have heard ion and java don't play nice together
22:03	ben_m	Musca
22:04	ben_m	tiling too
22:04	ltyphair	compiz turned on has given me trouble before. the java window would end up under the panel
22:04	ben_m	But I doubt that's the problem
22:04	ben_m	Nah, no compiz.
22:04	hiredman	ben_m: why do you doubt it?
22:04	ben_m	I had other Java programs running
22:05	ben_m	Not in Musca specifically, but other tilers.
22:07	the-kenny	ben_m: uhm.. you're calling the function "counter-app", right?
22:07	hiredman	works for me
22:07	ltyphair	for what it worth the code works on gnome.
22:11	ben_m	the-kenny: yes?
22:11	ben_m	Hmm alright then
22:11	ben_m	Everything about my PC acts in mysterious ways, so this does not surprise me.
22:30	ben_m	Is there a shortcut in the REPL to get the last result? Like //** in CL
22:35	hiredman	1 2 *3
22:36	ben_m	ah, thanks :)
22:38	hiredman	(doc e*)
22:38	clojurebot	Excuse me?
22:38	hiredman	(doc *e)
22:38	clojurebot	"; bound in a repl thread to the most recent exception caught by the repl"
22:40	konr`	it seems that my JVM is computing data on an infinite sequence - is there a way to recover without killing slime (therefore losing the session data)?
22:41	ben_m	C-c C-c 0
22:41	ben_m	?
22:45	konr`	wow
22:45	konr`	thanks, ben_m
22:45	wilig	technomancy: Yay! swank-clojure is now (read-line) enabled.
22:45	konr`	I used to ignore that debug menu
22:45	ben_m	Heh, it can do so much more if you use Common Lisp.
22:51	mattrepl	is there a known issue with leiningen's test command?
22:52	aldebrn	liebke, I'll post this to the group, but maybe I'm doing something stupid: when I start clj (from the latest Incanter snapshot build) and (use 'incanter.core), Clojure can't find the "shuffle" function (from contrib.seq-utils).
22:53	aldebrn	If I try to (use 'clojure.contrib.seq-utils), I get an IllegalStateException, but after which I can see shuffle, e.g., (doc shuffle)
22:54	aldebrn	So, I can work around this by using the REPL, but it prevents me from running scripts that use shuffle
22:54	liebke	aldebrn: okay thanks, I'll take a look. Were you using the pre-built distribution or building it from source?
22:54	aldebrn	Pre-built
22:54	liebke	okay, I'll test it out
22:55	aldebrn	Thanks for your selfless hard work
22:55	liebke	:)
22:58	liebke	aldebrn: I'm getting the error. What platform are you running on?
22:58	aldebrn	Fedora 11 64-bit
22:59	liebke	do you have a CLASSPATH set?
22:59	aldebrn	java version "1.6.0_0" OpenJDK Runtime Environment (IcedTea6 1.6)
22:59	aldebrn	No CLASSPATH appears to be set
23:00	liebke	I don't have fedora, but I'll test it on redhat 64-bit
23:01	aldebrn	You said you were getting the "IllegalStateException: group-by already refers to: #'incanter.core/group-by in namespace: user" error?
23:02	liebke	I said?
23:03	aldebrn	"liebke> aldebrn: I'm getting the error." <-- did you mean you're not getting an error?
23:03	liebke	oops yeah, I meant I'm not getting the error :)
23:03	liebke	is that the error you're getting?
23:04	aldebrn	Yes, when I try (use 'clojure.contrib.seq-utils)
23:04	liebke	ah yes, I've seen that one. That's because it also has group-by defined
23:05	liebke	you need to use require instead of 'use' for either incanter.core or seq-utils
23:05	aldebrn	Ahh, so does incanter.core, got it
23:05	aldebrn	Ok
23:05	liebke	yeah, name collision
23:13	aldebrn	liebke, sorry to bother you again, how would I use (require) with seq-utils?
23:15	mattrepl	aldebrn: (require [clojure.contrib.seq-utils :as seq-utils])
23:15	mattrepl	then seq-utils/group-by
23:15	mattrepl	you can also do (use [clojure.contrib.seq-utils :only [<stuff> <you> <need>]])
23:16	mattrepl	and that should be :require and :use if used in a namespace definition
23:18	aldebrn	mattrepl, thanks, something somewhat strange is happening: (use 'clojure.contrib.seq-utils) works fine (by itself), but (use [clojure.contrib.seq-utils :only [shuffle]]) gives this horrific ClassNotFoundException: clojure.contrib.seq-utils (NO_SOURCE_FILE:1) ?
23:19	aldebrn	Similarly with your example using (require), am I typing something wrong?
23:19	mattrepl	right, I gave you a bad example since it's incorrect for an ns definition as well as from the repl
23:19	mattrepl	you need to quote clojure.contrib.seq-utils and shuffle
23:19	liebke	aldebrn: try (require '(clojure.contrib [seq-utils :as s]))
23:20	aldebrn	Ahh, damned quotes
23:20	aldebrn	Thank you thank you
23:20	liebke	and then you can refer to functions using the s prefix, like s/group-by