#clojure – 2009-10-25

2009-10-25

00:51	qed	how do you compare to strings
00:51	qed	like (= str str)
00:51	qed	or (== str str)
01:04	danlarkin	(doc =)
01:04	danlarkin	(doc ==)
01:04	scottj	qed, =
01:21	defn	How do I do a decrementing while loop in clojure?
01:22	defn	I'm taking some input to this function, an integer
01:22	defn	I want to decrement that integer until a function on the same input is true
01:22	defn	and return that integer
01:26	lisppaste8	cema pasted "md5" at http://paste.lisp.org/display/89237
01:29	Guest16869	defn: for example like this: (defn foo [n] (if (<= n 3) n (recur (dec n))))
01:30	defn	danlei: what about with true/false?
01:30	danlei	what do you mean?
01:32	defn	danlei: http://pastie.org/private/dg1vj8nxhvmk00hjw0jpg
01:32	defn	that first function, reverse-and-test is testing to see if the input and the reverse of the input are equal
01:32	defn	it takes an int
01:33	defn	in test-down we want to sart at 998001, and decrement that number until we find a palindrome
01:33	defn	danlei: does that make sense?
01:36	danlei	defn: (defn palindromep [n]
01:36	danlei	(= n (read-string (apply str (reverse (str n))))))
01:36	danlei	defn: if you use that instead of (<= n 3) in the example above, it'll work
01:36	danlei	don't know if it's elegant, I just followed the string-reversion approach
01:37	danlei	(defn foo [n] (if (palindrome? n) n (recur (dec n)))) [untested]
01:39	defn	string-reversion approach?
01:39	danlei	number -> string -> reverse -> number
01:39	defn	are you a Haskell guy?
01:40	defn	the '->'s make me suspicious
01:40	danlei	no :)
01:42	defn	that doesn't work
01:42	danlei	(palindrome? 11) true
01:42	danlei	(palindrome? 12) false
01:42	danlei	what shouldn't work there?
01:43	defn	that works fine
01:43	danlei	(defn find-palindrome [n]
01:43	danlei	(if (palindrome? n)
01:43	danlei	n
01:43	danlei	(recur (dec n))))
01:44	defn	but let's say we're starting at the number 998001 and want to test every number, decrementing by 1, until we find a case that is true
01:44	danlei	(find-palindrome 15)
01:44	danlei	11
01:44	danlei	I don't see the problem, can you elaborate?
01:44	danlei	or, if you don't like recur ...
01:45	danlei	(first (drop-while #(not palindrome? %) (iterate dec 998001))) [untested]
01:46	defn	java.lang.NumberFormatException: Invalid number: 000899
01:46	defn
01:46	danlei	ah, ok
01:46	danlei	wrap it in a try block
01:46	danlei	not elegant, but should do
01:46	defn	this started out so pretty
01:47	defn	and now is descending into a pool of liquid shit
01:47	defn	lol
01:49	danlei	or just use Integer/parseInt instead of read
01:54	danlei	defn: btw. I tested it and it found the number without any problems
01:55	danlei	(without changing anything)
01:55	qed	even from 998001
01:55	qed	?
01:56	qed	oopa
01:56	defn	even from 998001?
01:57	danlei	with parseInt: (defn palindrome? [n]
01:57	danlei	(= n (Integer/parseInt (apply str (reverse (str n))))))
01:57	danlei	(first (drop-while #(not (palindrome? %)) (iterate dec 998001)))
02:03	defn	thanks
02:04	danlei	not without changing anything tough: forgot () around (palindrome? %) above
02:08	danlei	defn: this is better: (first (filter palindrome? (iterate dec 998001)))
02:08	defn	nice filter
02:08	defn	thanks
02:09	danlei	welcome
02:12	defn	danlei: could you explain how (let [products (for [a (range 100 1000) b (range 100 a)] (* a b))] (reduce max (filter palindrome? products))) works?
02:12	defn	I don't understand the [ [ []]] stuff within the let, nor how it is passed forward to the reduce max fn
02:13	qed	im still here
02:13	qed	fwiw
02:22	danlei	defn: (for [a (range 100 1000) b (range 100 a)] (* a b)) iterates for a from 100 to 100 and b from 100 to a, computing the product of them. this gets bound to procucts, which is then passed to filter in the body of the let
02:24	danlei	defn: try to reduce the code to smaller examples, and you'll understand. like: (for [x '[a b] y '[c d]] (list x y)) will give you the permutations of [a b] [c d] ...
02:25	danlei	where in [x y] x is out of [a b] and y is out of [c d]
04:37	yason	In an agent action, how do I know which agent was it sent to?
04:38	yason	If I'm to resend the action again from the action itself, I kind of need to know the agent. ants.clj used agents that was defined nowhere in ants.clj but didn't seem to be in Clojure 1.0 either.
04:48	cgrand	yason: agent
04:48	cgrand	is bind to the current running agent
04:53	yason	cgrand: I saw that and I think I tried that; perhaps I'll cross-check my experiments. Was it documented somewhere?
04:54	hiredman	it is
04:55	hiredman	also documented is the fact that agents hold sends until the completion of an action
04:56	yason	The docstring for agent is there, perhaps I just didn't find it on the Clojure website.
04:56	cgrand	yason: http://clojure.org/api#toc9
04:56	yason	cgrand: of course, thanks!
04:56	cgrand	but no mention of it on clojure.org/agents
04:57	yason	cgrand: would've helped if it had been mentioned on the Agents page :)
06:18	ambient	threads are still completely controlled with Java interop, right?
06:18	ambient	and the message passing between threads
06:32	Chousuke	ambient: you can use any of the clojure concurrency constructs instead of using threads directly
06:33	Chousuke	but yeah, if you do need full control for some reason, it's done via Java interop.
06:33	ambient	but if i need to run high-performance computing in the background and send and receive messages from and to that "engine"?
06:34	ambient	what would be the best way to do this with clojure?
06:35	ambient	(not HPC, just fast math)
06:36	Chousuke	hmm.
06:37	ambient	the point is to control it from REPL like this: (start-engine) (send-stuff some-stuff) (stop-engine)
06:37	Chousuke	well, you might be able to use watchers.
06:37	Chousuke	and an agent for serialising the message sends
06:38	ambient	ok, going to check out watchers
06:39	ambient	the engine might run with IO call-back thread
06:39	ambient	minus thread
06:40	ambient	basically it can be considered as an audio mixer that's constantly sending data. (send-stuff) sends a buffer that contains some information how to generate a wave
06:40	ambient	or changes some values in the engine
06:41	ambient	if it got no inputs, it just generates and plays silence
06:41	Chousuke	I guess you should just use plain threads.
06:55	AWizzArd	Is it only me, or do you also see http://github.com/richhickey/ as pretty empty?
06:55	ambient	AWizzArd only you
06:55	AWizzArd	ah ok, website is back
06:55	ambient	depending of your definition of empty
06:56	AWizzArd	got a 404, nginx
06:56	ambient	k
06:56	ambient	http://downforeveryoneorjustme.com/ is pretty useful site
07:57	ambient	anyone care to interpret this error message? java.lang.IllegalStateException: src already refers to: #'amb.synth.audioloop/src in namespace: amb.synth.audioloop (audioloop.clj:1)
08:16	ambient	if i have (def src foo) somewhere else and then try (let [src bar] ...) it gives an error?
08:17	AWizzArd	no
08:18	AWizzArd	You shadow the def'ed src with your let, but this throws no error.
08:18	ambient	if i have src defined in amb.synth.engine and try to (def src foo) in amb.synth.audioloop, which uses ...engine it gives an error?
08:19	ambient	what is weird that i don't have "src" anywhere in my code
08:19	AWizzArd	That could throw an error, because src is imported and you try to name something else like that.
08:19	ambient	it's some reserved variable?
08:19	AWizzArd	No
08:20	AWizzArd	do you know in which package src is?
08:21	ambient	hmm, (ns (:use)) doesn't seem to inherit the uses
08:21	ambient	amb.synth.audiochan > amb.synth.engine > amb.synth.audioloop => audioloop can't find audiochan
08:22	ambient	so perhaps all the error were caused by leftovers in the SLIME environment
08:25	ambient	yep
08:29	AWizzArd	you started a fresh jvm?
08:29	ambient	yes
08:40	adityo	hello
08:40	AWizzArd	Hi Adi
08:42	adityo	hey AwizzArd :)
08:43	adityo	im trying to traverse a directory tree , get something from each file
08:43	ambient	clojure really needs a native power function :/
08:43	adityo	(for [file (file-seq (File. "dir"))])
08:44	adityo	yet i get an error FileNotFoundException (is a directory)
08:48	spuz	Does anyone know what this error means? "java.lang.IllegalArgumentException: recur arg for primitive local: x must be matching primitive"
08:52	spuz	This seems to happen when I try to cast a local variable to a primitive type inside a 'loop' definition
09:01	chouser	spuz: you need to make sure that the matching arg in the 'recur' is also primitive
09:04	spuz	chouser: if I say (let x 2.0), is x not a primitive?
09:04	spuz	or (let [x 2.0]) even
09:05	chouser	spuz: right, literal numbers are boxed
09:05	chouser	so instead try (let [x (double 2.0)])
09:05	spuz	chouser: ah ok
09:07	AWizzArd	adityo: did you try (.list (File. "/"))?
09:08	AWizzArd	btw, how do I get a sequence of all namespaces that are currently loaded?
09:08	chouser	AWizzArd: all-ns
09:08	AWizzArd	ah right
09:08	AWizzArd	ambient: why?
09:10	chouser	adityo: (for [f (file-seq (java.io.File. ".")) :when (.isFile f)] ...)
09:35	ambient	AWizzArd so i dont have to do (bit-shift-left 2 32) or (int (Math/pow 2 32)) all the time
09:36	ambient	(.start (Thread. foo-bar)) seems to block. how do i get a non-blocking thread?
09:36	ambient	from the REPL
09:37	chouser	that doesn't block the current thread
09:38	ambient	yes
09:39	ambient	my code currently looks like this: http://paste.pocoo.org/show/146866/
09:39	ambient	the intention is to call (eng-start) from the REPL, then after (eng-stop)
09:40	ambient	waiit.. perhaps i need to give a fn to the Thread.
09:40	chouser	yes you do.
09:40	ambient	hah! :P
09:40	ambient	thanks
09:40	chouser	btw, don't use 'def' inside a 'defn' like that.
09:41	chouser	'def' does not make a local
09:41	ambient	i know
09:41	ambient	but (def dl (atom (audiochan-open 44000))) does IO which I don't want to happen until (eng-start)
09:42	chouser	then do (def dl (atom nil)) at the top level, and (reset! dl (audio-chan-open 44000)) in the fn
09:42	ambient	ok
09:48	ambient	this is a bit embarassing how much functionality i can pack into so little amount of lines :/
09:52	ambient	heh, i now have a fully functioning FM synthesizer from the REPL :p
09:52	ambient	now just to connect midi-input
09:52	rhickey	ambient: cool!
09:52	ambient	thanks :)
09:56	AWizzArd	ambient: can you play the piano in the repl? :)
09:56	ambient	not yet
09:56	rhickey	http://emusician.com/images/archive/backissues85-90.html EM March 1988 REVIEWS: Savant Audio Edit-8000 (mine)
09:56	ambient	i need to do envelope-generator that's triggered by the midi
09:59	AWizzArd	oh, 20 years og
09:59	AWizzArd	ago
10:00	rhickey	I should have said waaay back :)
10:01	chouser	I may have been transitioning from QuickBasic to Pascal around then
10:02	AWizzArd	progress :)
10:03	chouser	"Desk accessory to load patch files available free via BBS"
10:03	AWizzArd	does the new branch now have everything from master (and more, like defclass*)?
10:07	rhickey	http://www.atarimagazines.com/st-log/issue29/08-1_ST_NEWS_KORG_DSS-1_EDITING_SOFTWARE.php
10:07	AWizzArd	cute
10:08	rhickey	"but it does require one megabyte of RAM" :)
10:08	dreish	But, the Amiga had more colors and was therefore better!
10:08	ambient	atari had a midi-port built-in
10:08	ambient	:)
10:09	ambient	the times when normal computer magazines had articles like "how to program your C64 to read data from weather satellite"
11:53	lambdatronic	howdy folks. I've just run into something that just threw me a bit, and I'm looking for the rationale (or if this is a bug).
11:54	lambdatronic	I'm currently using Clojure 1.0.1-alpha-SNAPSHOT, and (= [] ()) and therefore (isa? [] ()) returns true.
11:55	lambdatronic	(isa? () []) also returns true.
11:56	lambdatronic	however, none of the other empty collection values are equivalent [i.e. (isa? () {}) (isa? () #{}) (isa? [] {}) (isa? [] #{}) (isa? {} #{}) (isa? {} []) (isa? {} ()) (isa? #{} ()) (isa? #{} []) (isa? #{} {})]
11:56	lambdatronic	So what gives?
11:57	rhickey	lambdatronic: isa? is not about instances, it's about types, so don't confuse with instance? or =
11:57	rhickey	when used with aggregates (i.e. vectors), it is about aggregates of types
11:57	lambdatronic	however, isa? performs = first before traversing type hierarchies.
11:58	rhickey	(isa? [String String] [Object Object])
11:58	lambdatronic	and its (= () []) that's throwing this all off.
11:58	lambdatronic	the = fails on all the other sentinel values as well.
11:59	rhickey	(isa? {} []) is not meaningful
11:59	rhickey	they are not types not aggregates of types
11:59	rhickey	the only supported aggregate is a vector of types/tags
12:00	lambdatronic	When would I see this in use? (and this still doesn't get at the heart of my question, which is why does (= () []) return true?)
12:01	Chousuke	an empty list is structurally equivalent to an empty vector, I suppose.
12:01	rhickey	lambdatronic: that's a different question having nothing to do with isa? - = on collections divides collections into families - sequential, map, set - members of the same family with the same contents compare =, otherwise equality would have extreme type brittleness
12:03	rhickey	(and (sequential? []) (sequential? ())) -> true
12:03	lambdatronic	hmm...but {} and [] don't compare equal although the key/val mapping functions both work on them.
12:04	rhickey	right, there will always be overlap in behaviors of collections, sequential/map/set is just one way to separate them
12:04	rhickey	a vector is not a full map, even though it is somewhat associative
12:05	lambdatronic	alright, but = always follows this particular rule, so of the four underlying collection type, vectors and lists are lumped together while the others remain separate.
12:06	rhickey	the whole phrase 'underlying collection type' implies a lumping already, i.e. sorted and hashed sets, many flavors of maps
12:08	lambdatronic	right, I got that. But given the way the language documentation stands, those lumpings were already presented as being pretty intuitive. saying that lists and vectors are = if their contents are equal just crosses a boundary in my mind that comparing array-maps and struct-maps wasn't likely to.
12:08	lambdatronic	but now I know, I guess, and knowing is the half the battle.
12:08	lambdatronic	;)
12:08	rhickey	equality deals with the collection taxonomy at a level where there are 3 lumps, and that matches the lumping that occurs in j.u.Collections as well
12:09	lambdatronic	ah, therein lieth the rationale.
12:09	lambdatronic	it's a javaism.
12:11	lambdatronic	I see now the other spooky things one can do with this => (= [1 2 3 4] (seq #{1 2 3 4}))
12:11	lambdatronic	or (= '([1 2] [3 4]) (seq {1 2 3 4}))
12:12	rhickey	lambdatronic: no, it is not a Javaism, it was there before they were aligned. I think there's more utility to sequential equality than separating the two
12:13	lambdatronic	yeah, I'm seeing that rich. hence my last two examples.
12:13	rhickey	the rationale is simply one of at what level is it most useful to use the abstractions, presuming one would never want exact type match included in collection equality
12:13	lambdatronic	that is the presumption, yes.
12:14	lambdatronic	it's the one that threw me. I was working through a haskell book and implementing all the exercises in their equivalent clojure, to compare and contrast the language features.
12:14	rhickey	it can be difficult to see the abstraction due to the overlaps, but a lot of the utility in Clojure comes from maximizing the use of the abstractions, i.e. extending to as many cases as makes sense and are efficient
12:15	lambdatronic	I was examining pattern matching, and I noted that a lot of pattern matching is just for destructuring binding (which was easy enough to map to clojure).
12:15	lambdatronic	sure enough, dynamicity is the name of the game, after all.
12:16	rhickey	I thought there were some docs on how collection equality worked, but can't find them now...
12:16	lambdatronic	it's when I was looking for a native way to map pattern matching for different argument values that I switched over to multimethods and hit the wall when trying to distinguish between an empty list and an empty vector. hence my question (and its original phrasing with isa?).
12:16	lambdatronic	nor can I...
12:16	rhickey	instance? is what you want there
12:17	rhickey	or the abstraction-blah? predicates
12:17	lambdatronic	you mean like vector?, map?, seq?, list?, set?
12:18	rhickey	yeah:
12:18	rhickey	user=> (seq? ())
12:18	rhickey	true
12:18	rhickey	user=> (seq? [])
12:18	rhickey	false
12:18	lambdatronic	hmm...sneaky
12:19	lambdatronic	so let me ask again quickly about the aggregates of types you were discussing earlier.
12:19	lambdatronic	how would I use that with isa?
12:20	lambdatronic	is it something like the opportunity to match multiple values?
12:20	rhickey	exactly
12:21	lambdatronic	sorry, I didn't phrase that correctly...too ambiguous
12:21	lambdatronic	as in, is this a disjunctive or a conjunctive match?
12:22	rhickey	conjunctive
12:23	rhickey	since dispatch functions in multimethods can return only a single value, this lets you return a value (vector of types/tags) and have the built in isa? match all
12:24	lambdatronic	so my multimethod dispatch function has to return a sequence of values (which may be anything sequential), and my matching dispatch values will all use a vector to represent them?
12:24	lambdatronic	ok
12:25	rhickey	vectors only
12:25	lambdatronic	so why are vectors the only allowed matchable collections?
12:25	rhickey	fast count test
12:25	lambdatronic	hmm
12:27	rhickey	basically, they do the job and adding generatily wil lslow things down, no need here
12:28	lambdatronic	no worries, I've got a heuristic lexer/parser in my brain. ;)
12:29	lambdatronic	but I see that multimethods will match on maps, sets, etc.
12:29	lambdatronic	as in, I just tried it, and it worked.
12:30	lambdatronic	so remind me again where the vector-only restriction comes into play? I get the sense I'm missing something important here.
12:30	lambdatronic	or just being dense.
12:31	chouser	since you want to compare two collections with different values in them, you need them to be sequential to get sensible results, right? maps and sets don't make sense.
12:32	lambdatronic	chouser: please see 3 posts back.
12:32	chouser	but the position matters.
12:32	lambdatronic	(= {:a :b :c :d} {:c :d :a :b})
12:32	lambdatronic
12:33	lambdatronic	and of course, that works just fine, as expected.
12:33	lambdatronic	again, see the post I just made.
12:33	chouser	right, but often you want to check inheritence, not equality
12:34	lambdatronic	so when we're talking about the vector-only matching, we're strictly speaking about the inheritance checking post-equality testing?
12:35	chouser	well -- I'm saying non-sequential things don't even make sense because of that. The restriction to vectors only may be more involved.
12:36	rhickey	lambdatronic: the only collection supported for isa? is vector, and the only reason to pass a vector is that you have more than one type relationship you want to test in a single isa? call. isa? is not instance?
12:36	chouser	(derive ::A ::D) (derive ::B ::C)
12:36	chouser	(isa? [::A ::B] [::D ::C]) ;=> true as you'd expect
12:37	chouser	(isa? #{::A ::B} #{::D ::C}) ;=> false, because it doesn't really make sense
12:38	lambdatronic	okay, I see your point now.
12:38	lambdatronic	it's just helpful with the clojure derive functionality.
12:39	lambdatronic	or the java class hierarchy too, of course
12:40	rhickey	isa? is about types/tags - saying (isa? () []) doesn't ask the question, "isa list a vector?', it asks the (unsupported) question, "is each member of this list isa? the corresponding member of the vector?" - being empty means you are not testing anything really
12:41	chouser	addMethod could throw something if given an non-vector collection
12:41	rhickey	isa? isn't bound to multimethods
12:42	chouser	right, but defmethod isn't speed critical like isa?
12:42	lambdatronic	yep, got that, rich. thanks. it was never the deriving part of isa that I was confused about. as I said earlier, what I didn't understand was why the two were =. Since isa? performs = first and I was doing the comparison with multimethods in my code, I just associated the problem with isa? in my first post (though I meant =).
12:43	lambdatronic	but you cleared up your rationale for why (= [] ()) is true. so all is well in the world.
12:43	rhickey	chouser: but non vectors aren't wrong, if you want the equality test
12:43	lambdatronic	thanks again, guys. keep on hackin' in the free world. I'm out.
12:45	rhickey	i.e. you could dispatch on sets, vectors just get 'isa-enhanced' equality
12:46	chouser	ah, I see. I didn't realize isa? was explicitly checking for vectors before doing isa? on the items.
12:47	rhickey	that needs better docs I guess
12:48	rhickey	so it looks like we can do the vast majority of the rest of deftype and defclass on the macro side of things, expanding into defclass* thus far
12:49	rhickey	the one big sticking point is the unavailability of the class being defined, and the fact that all interop compilation uses reflection and thus needs a Class object...
12:50	rhickey	and you end up needing the class-being-compiled quite often to avoid reflective calls to: its ctor in copying ops, fields of other instances of the same type, instance? checks, arg hints of same type
12:52	chouser	gotta go buy carving pumpkins. bbl.
13:22	ambient	how can I stop a macro from adding the namespace to the variable? http://paste.pocoo.org/show/146907/
13:23	ambient	i need evt and val just as they are, without any namespaces in front of them
13:23	spuz	Does the clojure compiler generate intermediate .java files before the .class files are generated?
13:24	robsynnott	Doubt it; doesn't it generally compile to JVM bytecode, not java?
13:25	spuz	I expect so
13:26	spuz	but perhaps there is some way to view the output of the compiler as generated java code...?
13:26	ankou_	hi, what exaclty is the graphical inspector?
13:26	ankou_	is there an article or something like that? can't find anything about this topic
13:26	spuz	I've tried decompiling the generated .class files but it really doesn't make sense as the code generated wouldn't appear to compile
13:27	ambient	clojure.contrib.swing-utils is a bit useless for me without a tutorial :(
13:32	notallama	ambient: ` adds namespace, ' doesn't. so you can unquote something and requote it like `(blah blah ~'x blah blah)
13:33	ambient	aha :)
13:34	chouser	spuz: Clojure compiles directly to bytecode that can in many cases not be represented correctly as .java
13:34	spuz	chouser: heh, thought as much :p
13:35	somnium	anyone tried using jad or similar on clojure's .class files?
13:37	chouser	ankou_: (require 'clojure.inspector) (clojure.inspector/inspect-tree {:a 1 :b {:c 2 :d 3}})
13:43	spuz	somnium: I've tried JD-GUI: http://java.decompiler.free.fr/?q=jdgui
13:43	spuz	sometimes it gives useful results
13:44	spuz	in my case though it seems the body of the function I'm looking at does absolutely nothing!
13:51	AWizzArd	~seen kotarak
13:51	AWizzArd	hiredman: bot gone?
13:53	chouser	rhickey: even if interop didn't use reflection, but instead examined .jar and .class files, that wouldn't help avoid reflective calls to defclass* classes.
13:59	chouser	right? so interop using reflection but sharing a classloader for a whole file might be closer to the right answer?
14:22	spuz	I'm still not really sure what the difference is between a closure and an anonymous function. Can someone explain what this example would do if Clojure did not support closures? http://lispwannabe.wordpress.com/2008/10/24/closures-in-clojure/
14:25	rys	the closure closes over state
14:25	rys	The anonymous function is just that
14:26	rys	It's a function with no ident
14:26	chouser	spuz: without closures, 'x' would not be defined in (fn [y] (+ x y))
14:27	spuz	chouser: so you would get an error saying "x not defined in this context"?
14:27	toups	Is there something like doseq but which executes in parallel? I have a body for which has side effects (writes to files) but not to any of the same files for a given element of the seq, so I should be able to parallelize it trivially.
14:28	Chousuke	use pmap with dorun
14:28	chouser	spuz: right
14:29	toups	(dorun (pmap (fn ...) sq))?
14:30	toups	Chousuke: like th at?
14:30	Chousuke	yeah
14:30	toups	Thanks
14:30	Chousuke	spuz: anonymous functions and closures are orthogonal concepts. a named function can form a closure too.
14:31	AWizzArd	spuz: you have a function F with a parameter vector P and a body B. In B a variable is accessed which is not in P, but also not a global var.
14:31	Chousuke	just do (let [foo bar] (defn ...))
14:31	spuz	I've only ever seen closures using anonymous functions but that makes sense
14:32	AWizzArd	spuz: you can use Closures in non-anon functions as replacement for (Java) classes.
14:32	Chousuke	they're much more common as anonymous functions
14:32	AWizzArd	Imagine you have a Point object, with the members x and y. You want to create a new point, or update one.
14:33	AWizzArd	You could have a (let [x 0, y 0] (defn make-point ..) (defn distance ...)) and so on.
14:33	AWizzArd	Then make-point and distance adn your other functions would be like methods in a Java class, and x and y are like the fields of the class Point.
14:37	toups	wheee - clojure is pretty fun.
15:03	Qvintvs	does anyone know why I'm getting clojure.lang.PersistentArrayMap cannot be cast to java.lang.Number from this code (line 33): http://pastebin.org/48210
15:04	The-Kenny	Qvintvs: Where in this code?
15:04	Qvintvs	line 33
15:08	The-Kenny	Qvintvs: The problem is in add-to-map called by get-words.
15:08	The-Kenny	Qvintvs: Do you really want to emit "words" two times to add-to-map?
15:11	Qvintvs	The-Kenny, ah, thx
15:13	The-Kenny	Qvintvs: I think zou also switched the last two values... v should be a number and not an object.
15:13	The-Kenny	s/zou/you/
15:13	Qvintvs	The-Kenny, ya, i noticed that too
15:57	hiredman	clojurebot: ping?
15:57	clojurebot	PONG!
15:57	somnium	,(#(%) #(+ 2 3))
15:57	clojurebot	5
15:58	somnium	hiredman: you turned off the I-Ching?
15:58	hiredman	(+ 1 4)
15:58	clojurebot	suffusion of yellow
15:59	somnium	oh good
16:05	somnium	,(doc rfirst)
16:05	clojurebot	Excuse me?
16:06	somnium	some functions on the cheatsheet http://clojure.org/cheatsheet don't seem to be there
16:08	hiredman	the cheatsheat is kind of out of date
16:08	hiredman	,(doc nfirst)
16:08	clojurebot	"([x]); Same as (next (first x))"
16:09	somnium	is that what rfirst did, or was it (rest (first x))?
16:10	licoresse	IMO, look at http://www.daimi.au.dk/~eernst/dPersp08/cheatsheet.pdf for what I think clojure.org needs
16:11	licoresse	there was a similar "terse guide to Smalltalk", but I cannot find it anylonger
16:11	somnium	yeah, that would be nice, python has some good ones too
16:12	somnium	makes it easy for anyone to get started
16:13	licoresse	ah, found it: http://74.125.77.132/search?q=cache:oaN12i4Gg0EJ:wiki.squeak.org/squeak/5699+terse+guide+to+squeak&hl=en&client=safari&strip=1
16:13	licoresse	that one helped me a lot when I was beginning squeaking
16:14	hircus	man, Clojure maps are fast -- http://hircus.wordpress.com/2009/10/25/mini-kanren-benchmarking-different-substitution-data-structures/
16:15	hircus	rhickey: any chance we could get IMapEntry's getter renamed to value() ?
16:16	somnium	licoresse: how did you learn to like the squeak gui?
16:17	licoresse	I didn't
16:17	licoresse	but when you have turtles all the way down
16:17	licoresse	you learn to like anything
16:17	licoresse	!!
16:17	licoresse	so I was in love for a couple of years
16:17	somnium	licoresse: too bad there's no emacs mode with buffers instead of windows
16:18	danlei	pharo looks a lot nicer than the vanilla squeak images imho
16:18	licoresse	somnium: you mean workspaces?
16:18	licoresse	the problem with squeak as many other similar things is that they have their own ecosystem
16:19	licoresse	and integrate poorly to the rest of the world
16:20	danlei	I'd love to have something like squeak/pharo for lisp. I ran medley in a VM (like genera, but for InterLisp), but it's quite aged ...
16:21	danlei	it still is a nice environment though
16:21	licoresse	well, I am happy to admit that Clojure is my new love now
16:21	somnium	I think if I had found smalltalk before I learned emacs I would have liked it, but when I tried it was already too unbearable to get started
16:21	licoresse	I only wish someone would do a proper debugger thing in emacs
16:21	danlei	somnium: I know what you mean :)
16:22	licoresse	somnium: it's not so much the language, which is fine, but more the environment
16:23	licoresse	the concepts of do-its, print-its etc
16:23	licoresse	and that brilliant debugger
16:23	danlei	for cl, the inspector and debugger are actually quite nice, don't get in your way
16:23	danlei	(slime)
16:24	licoresse	danlei: but none of that is avail to clojure, is it?
16:24	danlei	no, not that i'm aware of
16:28	somnium	'show and 'source in repl-utils do most of what I want for insepcting, but I don't what the CL inspector does
16:28	notallama	pointfree stuff is coming along nicely. i should probably do my homework, though :V http://github.com/hclarke/pointfree-clojure
16:29	danlei	somnium: there are restarts, eval-in-frame, goto-source ...
16:29	hiredman	oooo
16:29	danlei	somnium: you can eval code in a stack frame an restart it, for example
16:29	danlei	*and
16:30	somnium	notallama: that looks nice, I was lamenting the lack of something like your &&& and *** just yesterday
16:30	djork	oh man I would kill for a Squeak-like debugger in Clojure
16:31	djork	actually I just want Clojure errors instead of Java errors
16:31	djork	stack traces tha tis
16:31	licoresse	djork: that would help
16:32	licoresse	or that the slime-messages buffer scrolls correctly
16:32	djork	heh yes that too
16:32	hiredman	have you tried out clojure.stacktrace?
16:32	somnium	my favorite is 'no message', java null pointer, no source
16:32	licoresse	guess that is an easy thing to "fix"
16:33	licoresse	hiredman: no, I have not
16:33	licoresse	anyone written about it, a blog or something?
16:34	hiredman	nope
16:34	hiredman	I only found it because my reader was barfing on it while I was using it to build clojure
16:34	djork	hah
16:35	licoresse	ooo
16:35	licoresse	http://img.skitch.com/20090721-efy2e4wgsrhxs2cxsbnu4c4ftx.png
16:36	somnium	isn't that what slime does?
16:36	licoresse	sans colors
16:36	somnium	true
16:37	robsynnott	ooh, pretty
16:38	djork	wow, nice
16:38	djork	slime doesn't look like that for me
16:39	djork	1: user$eval__6140.invoke(NO_SOURCE_FILE:1)
16:39	djork	oh duh
16:39	djork	nevermind
16:41	danlei	http://danlei.nfshost.com/sldb.png
16:41	danlei	that would be nice to have in clojure too
16:42	somnium	wow
16:42	somnium	I hope something like that is in the works somehow or other
16:42	danlei	and that's just the top of the iceberg
16:43	danlei	well,
16:43	danlei	the problem is, that for example "restart" are a feature of the cl condition system
16:43	danlei	it's not a slime thing per se ...
16:43	Chousuke	the JVM just has exceptions :/
16:43	licoresse	'clojure.stacktrace is actually quite nice
16:44	licoresse	just need to connect it properly to the 'slime-compilation-finished-hook
16:44	danlei	in short: there are conditions, handlers, and restarts. somewhere, a condition gets signalled, then, if a handler handles it, a restart is invoked. the restart is usually down the stack, the handler up the stack ...
16:45	danlei	if no handler handles a condition, it will be handled by a human, in the debugger
16:45	Chousuke	I wonder what it would require for Clojure to emulate the condition system.
16:45	somnium	licoresse: could you paste the .emacs line you used?
16:45	Chousuke	there's error-kit but... hm.
16:46	licoresse	somnium: it's just a (add-hook 'clime-compilation-finished-hook 'whatever-you-like)
16:46	licoresse	slime (not clime)
16:46	somnium	licoresse: so just 'clojure.stacktrace there?
16:46	licoresse	no no
16:46	licoresse	you need to call swank
16:47	licoresse	or send something to the swank process or whatever
16:47	licoresse	I am not completely understanding this yet
16:47	somnium	licoresse: ah, I thougt you had it hooked up already
16:47	licoresse	:-(
16:48	Chousuke	or you can bug technomancy to add it to swank-clojure next time he joins :P
16:48	somnium	licoresse: I've been putting off reading swank-clojure.el
16:48	licoresse	anyway, I think that the above-mentioned hook is only called when the compilation is successful, I have to test it more
16:49	Chousuke	it shouldn't be too difficult to conditionally enhance the repl if contrib is available.
16:49	licoresse	I lost the link, there was someone mentioning clojure in emacs
16:50	licoresse	like, extending elisp with clojure stuff
16:50	licoresse	somnium: swank-clojure.el is a mess
16:51	licoresse	I guess that is what you get when everything is global
16:51	somnium	licoresse: I know, I looked at it once :)
16:51	Licenser	ow a lot is going on here
16:52	somnium	I think I like it best as a black box
16:52	licoresse	heh
16:54	licoresse	wait a minute, I don't mean the swank-clojure.el is a mess, it's just a mess to my eyes - I am sure it's brilliant in it's own way ;-)
16:55	licoresse	it's just 250 lines long
16:55	somnium	I'm sure it makes perfect sense once it makes sense to you
16:57	hiredman	http://www.thelastcitadel.com/images/syntax.png this is a mess
16:57	somnium	heh
16:57	licoresse	hehe
16:58	licoresse	is that object oriented?? :D
16:58	hiredman	I spent a large chunk of yesterday tracing that out
16:58	somnium	I like in once of rich's presentations he had one of those with "There Will Be A Quiz!" in big letters
16:59	hiredman	that is the syntaxQuote method from SyntaxQuoteReader in clojure.lang.LispReader
16:59	hiredman	that is all in one method
16:59	somnium	good god
16:59	licoresse	ouch
16:59	hiredman	once I made the graph it made sense, but before that :(
17:01	somnium	hiredman: it reminds me of the inside of a neglected server
17:02	licoresse	actually most of it makes sense, it's just that when you graph it...
17:02	somnium	http://www.michaelaulia.com/blogs/wp-content/uploads/2009/10/messy-cable-solution.png
17:03	licoresse	hmm
17:08	Chousuke	hiredman: I think the worst part of implementing syntax-quote is the symbol resolution :P
17:10	licoresse	hehe, reading about CIP (Clojure Idiomatic Police)...
17:10	hiredman	we have those?
17:10	Chousuke	http://github.com/Chousuke/clojure/blob/sq-macro/src/clj/clojure/core.clj#L562 I'm still not sure this is right.
17:11	Chousuke	also I wonder why there is no syntax-highlighting :/
17:12	hiredman	the graph really helped me understand the flow
17:14	hiredman	I have five places where my reader still relies on LispReader: ReaderException, FnReader, ArgReader, EvalReader, and readDelimitedList
17:14	Chousuke	!
17:14	Chousuke	I might just have figured out the bug I have compiling Clojure with my reader.
17:15	Chousuke	epiphany out of nowhere
17:15	hiredman	huzzah!
17:15	licoresse	how wonderful!
17:15	Chousuke	now I hope I'm right.
17:17	notallama	is there a way to not have to type the classname for java static functions? like (sin x) instead of (Math/sin x) ? or do i just have to def the ones i want to something shorter?
17:17	Chousuke	contrib has static-import I think. maybe that would help?
17:21	somnium	does (into {} ...) always create an ArrayMap regardless of number of args?
17:21	Chousuke	,(class (into {} [1 2]))
17:21	clojurebot	java.lang.IllegalArgumentException: Don't know how to create ISeq from: Integer
17:22	Chousuke	... ?
17:22	Chousuke	ah
17:22	Chousuke	,(class (into {} [[1 2]]))
17:22	clojurebot	clojure.lang.PersistentArrayMap
17:23	Chousuke	hmm.
17:23	Chousuke	,(class (into {} (take 15 (repeatedly [1 2])))
17:23	clojurebot	EOF while reading
17:23	Chousuke	,(class (into {} (take 15 (repeatedly [1 2]))))
17:23	clojurebot	java.lang.RuntimeException: java.lang.RuntimeException: java.lang.IllegalArgumentException: Wrong number of args passed to: PersistentVector
17:23	notallama	Chousuke: yes, that is exactly what i needed. thanks! (it's called import-static)
17:23	Chousuke	,(class (into {} (take 15 (repeat [1 2]))))
17:23	clojurebot	clojure.lang.PersistentArrayMap
17:23	somnium	,(class (into {} (interleave (range 100) (range 100))))
17:23	clojurebot	java.lang.IllegalArgumentException: Don't know how to create ISeq from: Integer
17:23	Chousuke	,(class (into {} (take 50 (repeat [1 2]))))
17:23	clojurebot	clojure.lang.PersistentArrayMap
17:24	Chousuke	apparently :/
17:24	somnium	hmm
17:24	Chousuke	,(class (into {} (take 5000 (repeat [1 2]))))
17:24	clojurebot	clojure.lang.PersistentArrayMap
17:24	Chousuke	...
17:24	somnium	well, on the bright side, that means I have some very easy optimizations to implement :)
17:24	Chousuke	sorry, I'm stupid :D
17:24	Chousuke	all those maps had only one element.
17:24	hiredman	haha
17:24	Chousuke	should go to sleep.
17:25	somnium	,(class (into {} (partition 2 (interleave (range 100) (range 100)))))
17:25	clojurebot	java.lang.ClassCastException: java.lang.Integer cannot be cast to java.util.Map$Entry
17:25	hiredman	,(class (into {} (map vector (range 100) (range 100))))
17:25	clojurebot	clojure.lang.PersistentHashMap
17:25	somnium	ah
17:25	somnium	well, that solves that
17:32	somnium	(conj {} [1 2])
17:32	somnium	,(conj {} [1 2])
17:32	clojurebot	{1 2}
17:32	div	hiredman: you should consider spending an hour or 2 playing with graphviz nxt time you need to graph something like http://www.thelastcitadel.com/images/syntax.png
17:32	somnium	,(conj {} '(1 2))
17:32	clojurebot	java.lang.ClassCastException: java.lang.Integer cannot be cast to java.util.Map$Entry
17:33	hiredman	div: that is graphviz
17:33	div	what's with the scary lines :)
17:34	div	the boxes are familiar yes, but it just seems like you drew the connections with paint :p
17:34	hiredman	the dark arrows are control flow and the thin lines are, uh?, state flow?
17:34	hiredman	nah, it's all dot
17:35	div	i see
17:36	somnium	hmm, I guess (into {} '(:foo :bar)) isn't supported for performance reasons?
17:37	hiredman	eh?
17:37	hiredman	where are the keys and values?
17:38	somnium	it seems to be because lists don't implement IEditableCollection
17:38	somnium	but [:foo :bar] does
17:38	somnium	so that was the basis for my guess
17:39	hiredman	no
17:40	somnium	er, scratch that, re-reading into
17:40	hiredman	(into {} [:foo :bar]) and (into {} '(:foo :bar)) both won't work
17:40	somnium	I know
17:40	hiredman	(into {} '([:foo :bar])) does work
17:41	somnium	hmm
17:41	hiredman	(conj {} :foo :bar) doesn't work
17:41	hiredman	(conj {} [:foo :bar]) does
17:46	AWizzArd	though i find (assoc {} :foo :bar) documents the code better
17:47	hiredman	sure
17:47	hiredman	I'm not advocating conj over assoc for associative things, I am just trying to illustrate why '(:foo :bar) does not work and '([:foo :bar]) does in into
17:48	AWizzArd	yes
17:51	Licenser	somnium: how is the mongodb driver going?
17:51	somnium	Licenser: a pre-alpha version is on github, its working but test coverage is poor
17:52	Licenser	wooh
17:52	somnium	Licenser: would be happy if you give it a try and let me know how it goes
17:52	somnium	been writing tests this afternoon
17:52	Licenser	somnium: I'm planing on it ;)
17:53	Licenser	somnium: how is it named?
17:54	hiredman	clojurebot: how is it named?
17:54	clojurebot	with style and grace
17:55	Licenser	ah found it
17:56	somnium	I considered mongojure and clomongo but they didn't appeal
17:56	Licenser	hah I tried mongojure :P
17:57	somnium	maybe 'clongo wouldn't be so bad
17:58	piccolino	somnium, so cool. I was just a week ago wishing there was a MongoDB driver for clojure taht worked like this.
17:59	somnium	piccolino: pre-alpha! :) please, let me know what breaks, I've a lot of improvements in mind, and it wasn't test-driven, more like repl-hacked
18:00	somnium	hiredman: sorry I'm being slow about this, how does the line in the source of conj ([coll x] (. clojure.lang.RT (conj coll x)) work ?
18:02	Licenser	somnium: I'm excited over your driver :P
18:02	hiredman	it's a call to the conj static method on RT
18:03	hiredman	anway, conj on maps takes a key-value pair
18:03	hiredman	'([:key :value]) is a sequence containg a key-value pair
18:04	hiredman	'(:foo :bar) is not
18:04	somnium	hiredman: ok, been putting off reading the .java portion of clojure, thanks
18:05	hiredman	somnium: you don't need to
18:06	hiredman	the point is '(:foo :bar :baz :bleep) is a flat sequence, '([:foo :bar] [:baz :bleep]) is a sequence of two element vectors
18:07	somnium	hiredman: right, but (list (list 1 2) (list 2 3)) also doesn't work, which is a sequence of two element sequences, or no?
18:07	hiredman	the first will not work because a. into uses conj (or did last time I checked) and b. it contains no key/value groupings
18:07	somnium	so I assume it has to do with how conj works
18:07	hiredman	that is because conj for maps takes a map entry, and two element vectors are map entries
18:08	hiredman	,(class (first {:a :b}))
18:08	clojurebot	clojure.lang.MapEntry
18:08	hiredman	,(first {:a :b})
18:08	clojurebot	[:a :b]
18:10	somnium	hiredman: ah, now it clicked, I wasn't thinking about the definition of map entries
18:24	hiredman	interesting trivia, (eval (eval (quote (list + 1 2 3)))) calls the reader to read (X.) where X is the name of the class the + fn is compiled to
18:24	LauJensen	~seen jdz
18:24	clojurebot	no, I have not seen jdz
18:30	Licenser	somnium: from the docs your API looks very neat
18:32	somnium	Licenser: it can still be improved, I'd like to completely suppress the class hierarchy defined by the java-api, but that will negatively impact performance for mass operations
18:33	Licenser	hmmm
18:34	somnium	Licenser: hopefully I'll get the core test suite finished this evening
18:34	Licenser	I have a request so :P fetch-one-with-defaults that would be very sweet
18:34	Licenser	s
18:34	Licenser	i
18:34	Licenser	since in the KV store you never can know what you get
18:34	somnium	Licenser: how would that work?
18:34	Licenser	well like:
18:35	Licenser	(fetch-one-with-defaults :robots :where {:name 'rodney'} :defaults {:type 'killer robot with laser eyes'})
18:36	Licenser	so it either returns {:name 'rodney' :type 'a cute little robot kitten'} or if rodney had no type {:name 'rodney' :type 'killer robot with laser eyes'}
18:36	hiredman	watch the single quotes
18:36	somnium	ah
18:36	Licenser	since I don't think mongodb allows field defaults as it has no scemes
18:36	Licenser	hiredman: thanks
18:37	piccolino	Does it work with hierarchical objects?
18:37	Licenser	piccolino: it does not work at all :P it's a dream of mien
18:37	piccolino	Sorry, I was asking somnium about the main functionality. :)
18:38	piccolino	I see that map-to-object just calls the mongo-java function, not sure how that one works yet.
18:38	somnium	piccolino: the core api is all json, so anything you can write in json you should be aple to express with a POCM (plain old clojure map)
18:39	somnium	or BSON I guess, but whatever, the structure is just like JSON
18:39	piccolino	So if I put a clojure map in a clojure map, the Java API will correctly structure that?
18:39	AWizzArd	yes
18:39	piccolino	Cool.
18:40	AWizzArd	you can also use the json parser in Clojure Contrib.
18:42	somnium	piccolino: they mongodb-java-driver also has a JSON/parse method that creates mongo objects, will probably wrap that in the next release
18:43	somnium	piccolino: but for the most part my goal was to create an illusion that youre using a DB that just knows how to speak clojure
18:43	piccolino	Totally, that's how it should be.
18:47	piccolino	I just guess the Java MongoDB driver had more reflection than I realized.
18:48	ankou_	hi, is there a simple search function like (first (filter x y)) but more efficient?
18:49	somnium	piccolino: far off in the future there could be a low level driver that does BSON to clojure, in the near future I want something easy and not broken to use for my own projects :)
18:49	piccolino	What would be the advantage of that?
18:49	somnium	piccolino: speed most likely
18:50	somnium	ankou_: try (some x y)
18:50	hiredman	some returns the result of the predicate
18:51	ankou_	which is true and not the element itself
18:52	hiredman	ankou_: what is the problem with (first (filter ...))
18:53	ankou_	well I thought that even if it uses a lazy sequence it might be slower then a real (convenient) find function or am I wrong?
18:54	somnium	,(some #(if (string? %) % nil) '(:foo :bar "yes" :wow))
18:54	clojurebot	"yes"
18:54	somnium	though I don't suppose that's better than (first (filter ...))
18:56	hiredman	ankou_: unless the input is sorted you are going to have to do a linear search, which is exactly what (comp first filter) does
18:58	somnium	,(time (first (filter #(= 2000 %) (iterate inc 1))))
18:58	clojurebot	2000
18:58	clojurebot	"Elapsed time: 13.013 msecs"
18:59	somnium	,(time (some #(if-let [x (= 2000 %)] x) (iterate inc 1)))
18:59	clojurebot	true
18:59	clojurebot	"Elapsed time: 9.003 msecs"
18:59	somnium	bah
19:00	somnium	,(time (some #(if (= 2000 %) %) (iterate inc 1)))
19:00	hiredman	,(time (some #{2000} (iterate inc 1)))
19:00	clojurebot	2000
19:00	clojurebot	"Elapsed time: 11.467 msecs"
19:00	somnium	nice, I don't use sets nearly often enough
19:02	somnium	,(time (first (filter #(= 100000 %) (iterate inc 1))))
19:02	clojurebot	100000
19:02	clojurebot	"Elapsed time: 383.559 msecs"
19:02	somnium	,(time (some #(if (= 100000 %) %) (iterate inc 1)))
19:02	clojurebot	100000
19:03	clojurebot	"Elapsed time: 168.427 msecs"
19:04	somnium	(time ((comp first filter) #(= 100000 %) (iterate inc 1)))
19:04	somnium	,(time ((comp first filter) #(if (= 100000 %) %) (iterate inc 1)))
19:04	clojurebot	100000
19:04	clojurebot	"Elapsed time: 218.176 msecs"
19:05	somnium	hiredman: internally, how different are (first (filter ...)) (comp first filter) ... and (some ...) ?
19:05	somnium	or at all?
19:06	hiredman	(comp first filter) creates a new function
19:07	hiredman	(first (filter ...)) doesn't
19:07	hiredman	which means there is an extra function invocation too
19:08	somnium	hmm, some and filter are very different
19:09	hiredman	~def some
19:09	somnium	why is filter so complicated?
19:09	ataggart	some is the complement of any
19:09	ataggart	erm
19:09	hiredman	some is not lazy
19:09	hiredman	filter is
19:10	ataggart	every? not any, sry
19:10	somnium	of course, and filter returns a whole collection, duh
19:11	somnium	'some' maybe isn't the best name for what it actually does, 'first-truthy' ?
19:11	hiredman	true for some elements
19:11	hiredman	some
19:11	ataggart	I like "any?"
19:12	somnium	hiredman: is there any way you could wire up clojurebot to 'source in repl-utils?
19:12	somnium	-> (defn some [pred coll] (when (seq coll) (or (pred (first coll)) (recur pred (next coll)))))
19:13	hiredman	,(use 'clojure.contrib.repl-utils)
19:13	clojurebot	java.lang.ExceptionInInitializerError
19:13	hiredman	clojurebot: same to you!
19:13	clojurebot	It's greek to me.
19:14	danlei	,(require '[clojure.contrib.repl-utils :as ru])
19:14	clojurebot	java.lang.NoClassDefFoundError: Could not initialize class clojure.contrib.repl_utils__init
19:15	danlei	didn't that use to work?
19:21	hiredman	,(use 'clojure.contrib.repl-utils)
19:21	clojurebot	nil
19:21	hiredman	,(source 'some)
19:21	clojurebot	java.lang.ClassCastException: clojure.lang.PersistentList cannot be cast to clojure.lang.Symbol
19:21	hiredman	,(source some)
19:21	clojurebot	Source not found
19:21	hiredman	:P
19:21	somnium	hiredman: is there anyway you could put the .clj files on his classpath without compromising his sandbox?
19:49	merijn	Do I understand it right that multi-methods are pretty much the same as pattern matching in Haskell, but with an explicit syntax to mark it?
19:51	notallama	they can be. i think it's closer to guards.
19:52	somnium	-> ((f x y z) x y z)
19:53	somnium	how does haskell's pattern matching work?
19:56	merijn	somnium: To use a trivial example (sum over a list, where [] is an empty list): "sum [] = 0; sum (x:xs) = x + sum xs" (or alternatively "sum [] = 0; sum list = head list + tail list")
19:56	merijn	err.. sum (tail list) in the latter example, of course
19:57	notallama	it's basically a destructuring bind, and you can put literals in it to match against.
19:58	somnium	x:xs = [x & xs] ?
19:59	hiredman	sort of
20:00	notallama	somnium: [[x & xs]], i think
20:00	merijn	somnium: ":" is list concatenation, so (x:xs) is a list with the first element bound as x and the tail bound as xs
20:00	hiredman	some wrote a pattern matching macro
20:00	hiredman	someone
20:00	hiredman	~matches
20:00	clojurebot	excusez-moi
20:01	hiredman	~google clojure pattern matching
20:01	clojurebot	First, out of 1630 results is:
20:01	clojurebot	brool » Pattern Matching In Clojure
20:01	clojurebot	http://www.brool.com/index.php/pattern-matching-in-clojure
20:01	somnium	hiredman: ooh, I was thinking about writing one yesterday
20:02	merijn	hiredman: Well, the point wasn't so much how to do pattern matching but if I could compare multi-methods to pattern matching in Haskell.
20:03	somnium	(doc match)
20:03	clojurebot	"clojure.contrib.types/match;[[value & clauses]]; Given a value and a list of template-expr clauses, evaluate the first expr whose template matches the value. There are four kinds of templates: 1) Lists of the form (tag x1 x2 ...) match instances of types whose constructor has the same form as the list. 2) Quoted lists of the form '(x1 x2 ...) match lists of the same length. 3) Vectors of the form [x1 x2 ...] match vector
20:03	notallama	merijn: multi-methods are more general. they dispatch on any function of the arguments you can think of.
20:04	somnium	are there any code examples for contrib.macros/macro-utils ? in the wild or elsewhere ?
20:04	hiredman	nice
20:04	hiredman	matching on constructor forms is great
20:04	notallama	so, it could choose a method by type, or by value, or by length of a string, or whatever.
20:05	somnium	I really wish there was a cheatsheet for contrib, I keep finding stuff I didn't know was thre
20:05	merijn	notallama: ok
20:19	Licenser	wow the mongodb community is quite fun
20:22	somnium	Licenser: ?
20:23	Licenser	somnium: yap, I just asked a question and ran into a bug, they are very helpfull in the channel :P
21:20	tomoj	technomancy: do you happen to know who maintains elpa gist.el?
23:12	technomancy	tomoj: no, sorry
23:21	lisppaste8	djork pasted "why does this throw a NPE?" at http://paste.lisp.org/display/89274
23:22	djork	If anybody can explain this mysterious error to me, I'd appreciate it.
23:22	hiredman	,(first '())
23:22	clojurebot	nil
23:22	djork	ah
23:22	djork	,(dec nil)
23:22	hiredman	,(dec (first '()))
23:22	clojurebot	java.lang.NullPointerException
23:22	clojurebot	java.lang.NullPointerException
23:22	djork	:)
23:23	djork	thanks
23:23	djork	by the way, iterate is a brilliant thing
23:24	djork	I love the fact that I can just do (nth (iterate next-day [5]) 1234)
23:24	djork	brilliant stuff
23:24	djork	of course my algo. here is not going to work (stack overflow)
23:26	djork	what's the best way to put conj and recur together so that I have a tail-recursion going on?
23:58	chouser	djork: walking a lazy seq shouldn't overflow the stack