#clojure – 2009-10-13

2009-10-13

00:05	ambient	http://paste.pocoo.org/show/144638/ anyone know how to do these highpass and lowpass filters better?
00:05	ambient	those functions just seem so awkward
00:05	durka42	what is it you're trying to do?
00:05	ambient	they're basically IIR filters
00:05	ambient	for example (lo-pass-crappy 0.2 (take 10000 (map #(- (* % 2.0) 1.0) (repeatedly rand)))) gives 10k samples of low-pass filtered noise
00:05	ambient	http://en.wikipedia.org/wiki/High-pass_filter
01:29	wavis	~def deref
01:41	peter_12	"Symbols beginning or ending with ':' are reserved by Clojure." Reserved for what?
01:43	chouser	generally later use
01:44	chouser	if you try to read a symbol starting with : you'll get a keyword instead
01:49	peter_12	chouser: so a keyword is its own datatype in clojure?
02:32	gilbertleung	hi everyone
02:38	gilbertleung	how do i find the first thing in a list that satisfies a certain predicate?
02:38	gilbertleung	is there a function for that?
02:38	arbscht_	,(doc find-first)
02:38	clojurebot	"([pred coll]); Returns the first item of coll for which (pred item) returns logical true. Consumes sequences up to the first match, will consume the entire sequence and return nil if no match is found."
02:38	arbscht_	that's in contrib
02:39	arbscht_	http://richhickey.github.com/clojure-contrib/seq-utils-api.html
02:39	durka42	note it's just (comp first filter)
02:43	gilbertleung	would filter work on an infinite list?
02:43	Chousuke	yes.
02:43	gilbertleung	cool, thanks
05:21	liwp	~max
05:21	clojurebot	max people is 182
05:21	jdz	nice, a disciple of AWizzArd
05:21	gerryxiao	hello
05:22	jdz	~max
05:22	clojurebot	max people is 182
05:22	jdz	fail
05:22	gerryxiao	(def board (proxy [JPanel] [] (paintComponent [g] (proxy-super paintComponent g) ...
05:23	gerryxiao	how to type hints for proxy-super?
05:23	gerryxiao	clojure complains paintComponent method can't be resovled
05:23	Chousuke	typehint g?
05:24	gerryxiao	not work
05:24	Chousuke	how are you doing it?
05:24	gerryxiao	#^Graphcis2D g
05:25	Chousuke	in the proxy-super call or in the argument list?
05:25	gerryxiao	in the proxy-super call
05:25	Chousuke	both should work, though, but perhaps not :)
05:26	gerryxiao	ok, let's try args
05:27	gerryxiao	not work
05:27	gerryxiao	i have typetints for board, also not work
05:28	gerryxiao	neither work
05:29	gerryxiao	Reflection warning, Personal/Gerry/GoBoard1.clj:99 - call to paintComponent can't be resolved.
05:29	Chousuke	hm. maybe proxy-super has a bug then :/
05:29	gerryxiao	does macro support type hints?
05:30	Chousuke	what do you mean?
05:30	Chousuke	you can attach a type hint to any clojure form, but it's up to you to ensure that it's the correct one :)
05:30	arbscht_	gerryxiao: paste your code?
05:31	gerryxiao	i mean whether i use type hints in defmacro
05:31	gerryxiao	arbscht_: what code?
05:31	Chousuke	gerryxiao: remember that the macro is a function that returns clojure code to be evaluated.
05:31	arbscht_	your proxy form
05:32	gerryxiao	ok
05:32	arbscht_	lisppaste8: url
05:32	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
05:32	Chousuke	gerryxiao: you must ensure that the clojure code returned is the one that has the type hints
05:34	Chousuke	for example, (defmacro foo [x] `(.someMethod #^Type ~x)) would fail because the type metadata doesn't get attached to the symbol that is the value of x
05:35	Chousuke	you'd need to do `(.someMethod ~(with-meta x {:tag 'Type}))
05:36	lisppaste8	gerryxiao pasted "proxy hints" at http://paste.lisp.org/display/88580
05:37	Chousuke	~def proxy-super
05:38	Chousuke	ah, that would be the problem
05:38	Chousuke	"this" in the proxy-super is not type-hinted
05:40	gerryxiao	proxy-super line not include this
05:40	Chousuke	yeah, but the implementation does
05:41	Chousuke	you need to do it manually: (proxy-call-with-super #(.paintComponent #^JPanel this g) #^JPanel this "paintComponent")
05:41	Chousuke	I hope that's correct :P
05:42	gerryxiao	ok, no this type hints, i can live however :)
05:53	Fossi	is there a doall map/for wrapper that signals sideeffects? in contrib or such?
05:54	Chousuke	hmm
05:55	Chousuke	what do you mean signals?
05:56	Fossi	i still often find myself forgetting the doall
05:56	gerryxiao	is clojure github reps broken?
05:56	Fossi	especially with constructs like (if (map println ["foo]) "something") where i more or less just want the side effect
05:57	Chousuke	you want a strict map?
05:57	Fossi	so i wonder if there's a "realize" or such in contrib
05:57	Fossi	which does (doall (map func! data))
05:57	Chousuke	(def s-map (comp doall map))?
05:58	Fossi	yeah, i know how to define it, i just wondered whether there is a "standard" function for that in contrib yet
06:00	tomoj	is map really OK for side-effects?
06:01	Fossi	eh, we just kinda had the same discussion. why shouldn't it be?
06:02	tomoj	I guess by itself it's ok
06:02	Chousuke	it is, but you must not forget to force it :)
06:02	Chousuke	unless you specifically want lazy side-effects
06:02	tomoj	but (doall (take 10 (map println ...))) is not so OK I think
06:03	tomoj	it's certainly not OK
06:03	tomoj	this makes me want to avoid mapping over side
06:03	tomoj	er, mapping over side-effects altogether
06:04	tomoj	but I guess if you force it immediately without passing it anywhere or doing anything else with it, it's OK
06:04	tomoj	isn't doseq sorta like what you're asking for?
06:05	tomoj	for a "doall for" wrapper anyway
06:19	licoresse	I need some input regarding compiling clojure files
06:20	licoresse	I've set the compile-files to true, and the compile-path is set to "classes"
06:20	licoresse	the full path has been added to the classpath
06:21	licoresse	does compile-path need to be the full path or is it enough with "classes"?
06:23	tomoj	my compile-path is just "classes"
06:24	licoresse	ok
06:24	LauJensen	Morning gents
06:24	licoresse	so a M-c-k should in theory produce a .class file then
06:29	ankou	is there a possibility to refer to the current line number/source file?
06:49	raek	,(class in)
06:49	clojurebot	clojure.lang.LineNumberingPushbackReader
06:51	raek	,(.getLineNumber in)
06:51	clojurebot	55
06:51	raek	I'm not too familiar with the line numbering readers
06:53	raek	but there should be some info in the javadocs, I think
06:54	raek	or here: http://github.com/richhickey/clojure/blob/master/src/jvm/clojure/lang/LineNumberingPushbackReader.java
06:56	raek	ankou: You can wrap your FileInputStream with that one, if you like
06:59	djpowell	,(disj! (transient #{1 2 3}) 1)
06:59	clojurebot	#<TransientHashSet clojure.lang.PersistentHashSet$TransientHashSet@f9a36a>
06:59	djpowell	,(disj! (transient #{1 2 3}) 1 2)
06:59	clojurebot	java.lang.ClassCastException: clojure.lang.PersistentHashSet$TransientHashSet cannot be cast to clojure.lang.IPersistentSet
07:00	djpowell	hmm, a bug in disj! there
07:00	ambient	can someone help me build better IIR filters as infinite seqs? http://paste.pocoo.org/show/144638/
07:01	ambient	need just some suggestions where to go from there
07:01	octe	if anything throws an exception in the repl i will see it if there's no try/catch involved right?
07:02	djpowell	if the exception isn't caught, the repl will print the exception name and message
07:02	djpowell	for more details type (.printStackTrace *e)
07:02	octe	strange
07:02	LauJensen	ambient, looks like you can implement both using reduce
07:03	ambient	LauJensen i dont know if i can make infinite seqs with reduce
07:03	ambient	wait..
07:03	ambient	i mean lazy
07:03	ambient	sorry i just woke up, i've yet to had my coffee
07:03	ambient	i'll check reduce
07:04	LauJensen	reduce is not lazy - which is evident from its wonderfully clear docstring :)
07:04	ambient	here's the whole code http://paste.pocoo.org/show/144676/ my purpose here is to make lo-pass and hi-pass part of a lazy infinite sequence
07:05	ambient	the audiochan-play part at the bottom
07:05	ambient	i don't really know if that's possible but i'm going to try anyway
07:06	Maddas	(assuming you actually want to compute the exact result)
07:06	ambient	some wise guy said to me yesterday that in clojure.contrib there's some code that can be used to implement this
07:07	ambient	Maddas i dont really care about exactness, just some way to filter high or low frequencies
07:08	raek	ambient: I think your project is really awesome!
07:08	ambient	raek heh, thanks :)
07:08	raek	you're making a synth, right?
07:08	ambient	yep
07:09	raek	I like the use of infinite sequences
07:09	ambient	*dB
07:09	ambient	they're basically streams
07:09	ambient	using the stream mental model i _should_ be able to program a modular synth
07:10	ambient	and streams in scheme are just infinite lazy seqs afaik
07:10	Maddas	ambient: I don't know any clojure, but won't your hi-pass function never return if coll is an infinite sequence?
07:11	ambient	Maddas that's because both hi-pass and lo-pass are not lazy infinite seqs at the moment. it's where i'm trying to go but am not yet
07:11	djpowell	if you can write it using cons and recursion, then you can slip the lazy-seq macro in to make it lazy
07:11	djpowell	see: http://clojure.org/lazy
07:13	tomoj	ambient: what are you using to make sound? some java lib?
07:13	ambient	javax.sound.sampled.*
07:13	ambient	core
07:14	raek	lazy-cons?
07:15	tomoj	sounds like fun
07:17	djpowell	lazy-cons is dead; you use lazy-seq + cons now
07:18	raek	oh
07:24	gerry_	hello
07:24	raek	hi
07:25	gerry_	why not defclass in clojure?
07:26	gerry_	as like ocaml or f#, both is fp language
07:26	tomoj	what do you need defclass for?
07:27	gerry_	i want define java class from clojure
07:27	gerry_	or interface
07:27	gerry_	especially interfaces
07:29	tomoj	you can define java classes without a defclass
07:29	rhickey	,(doc gen-class)
07:29	clojurebot	"([& options]); When compiling, generates compiled bytecode for a class with the given package-qualified :name (which, as all names in these parameters, can be a string or symbol), and writes the .class file to the compile-path directory. When not compiling, does nothing. The gen-class construct contains no implementation, as the implementation will be dynamically sought by the generated class in functions in an impleme
07:29	rhickey	,(doc gen-interface)
07:29	clojurebot	"([& options]); When compiling, generates compiled bytecode for an interface with the given package-qualified :name (which, as all names in these parameters, can be a string or symbol), and writes the .class file to the compile-path directory. When not compiling, does nothing. In all subsequent sections taking types, the primitive types can be referred to by their Java names (int, float etc), and classes in the java.lan
07:31	gerry_	that's great
07:33	LauJensen	http://groups.google.com/group/clojure/browse_thread/thread/d8064dbb94c5cd2c
07:33	LauJensen	Does anyone know why this year old suggestion to bring spit into core has not been accepted?
07:35	gerry_	rhickey should knew why :)
07:41	octe	this is probably dumb but.. how do i change this function to return the struct? http://pastebin.ca/1617651
07:45	hoeck1	octe: just make conn the last expression in the let form
07:46	hoeck1	octe: like: (let [conn (struct ...))] (.connect ...) conn)
07:48	gerry_	octe: not need get for map
07:50	octe	hoeck1, gerry_: thanks :)
07:52	spuz	if I have a vector such as [1 2 3 5 6 7 8], how can I write a function which returns a list of elements n for which the previous element is equal to n-1. In otherwords, a list of all the numbers that are 1 greater than the previous number?
07:53	LauJensen	octe I think you can eliminate 3x (get conn :channel) by wrapping your statements in (doto (get conn :channel)...) and instead of 'new' suffic the class with a period "."
07:55	Maddas	.oO( And I thought you needn't be worried about getting homework questions in #clojure ;-P )
07:55	tomoj	spuz: not exactly sure what you mean, but maybe:
07:56	tomoj	,(map first (filter (fn [[x y]] (= (inc x) y)) (partition 2 1 [1 2 3 4 5 6 7 8])))
07:56	clojurebot	(1 2 3 4 5 6 7)
07:56	tomoj	,(map first (filter (fn [[x y]] (= (inc x) y)) (partition 2 1 [1 2 5 6 3 3 4 7 8])))
07:56	clojurebot	(1 5 3 7)
07:56	eevar2	,(map inc [1 2 3 4 5 6 7])
07:56	clojurebot	(2 3 4 5 6 7 8)
07:56	tomoj	eh, I got it backwards, map second instead of first
07:56	eevar2	might be what he ment? ;)
07:57	spuz	it should return (2 3 6 7 8)
07:57	tomoj	,(map second (filter (fn [[x y]] (= (inc x) y)) (partition 2 1 [1 2 5 6 3 3 4 7 8])))
07:57	clojurebot	(2 6 4 8)
07:57	eevar2	^^ nm
07:57	spuz	,(map second (filter (fn [[x y]] (= (inc x) y)) (partition 2 1 [1 2 3 5 6 7 8])))
07:58	spuz	um...
07:58	clojurebot	(2 3 6 7 8)
07:58	tomoj	I don't see where (2 3 6 7 8) could come from
07:58	spuz	well it works :)
07:58	tomoj	ah, yes
07:58	spuz	thanks tomoj :)
07:59	spuz	now, I've just got to understand it
07:59	tomoj	just play around on the repl with the parts
08:00	tomoj	(partition 2 1 ..) takes partitions of size 2 stepping 1 each time, so it gives ((1 2) (2 3) (3 5) ...)
08:00	spuz	ok, yeah it makes sense. I've just got to figure out a slightly more complex version of that
08:18	AWizzArd	Is there a way to kill a running agent?
08:18	AWizzArd	Without checking in the agent fn for some signals which will then simply exit the function.
08:20	LauJensen	AWizzArd, one particular or can it be all agents?
08:21	AWizzArd	One particular. For example when my agent swap!s the value of an atom I might want to end its job from outside.
08:21	LauJensen	Its a self-calling agent ?
08:21	AWizzArd	No
08:21	LauJensen	So altering some shared 'running' variable is out of the question?
08:22	AWizzArd	If there is not already a built in function for that I will simply ask in the agent fn if (= running true) or something like that. I just thought there might be some other way.
08:22	tomoj	how do you know from the outside when the agent swap!s the value?
08:22	AWizzArd	uhm (if running ...) :)
08:22	LauJensen	(when running...) :)
08:23	AWizzArd	LauJensen: oki, I will do just that then.
08:23	LauJensen	I don't know of a function which does what you want specifically, but you're welcome to post the code if you want some more input
08:27	licoresse	,(doc compile-path)
08:27	clojurebot	"; Specifies the directory where 'compile' will write out .class files. This directory must be in the classpath for 'compile' to work. Defaults to \"classes\""
08:27	ambient	anyone know the fate of http://clojure.org/streams ?
08:27	ambient	(doc stream) is nil
08:27	clojurebot	"clojure.contrib.http.agent/stream;[[http-agnt]]; Returns an InputStream of the HTTP response body. When called by the handler function passed to http-agent, this is the raw HttpURLConnection stream. If the default handler function was used, this function returns a ByteArrayInputStream on the buffered response body."
08:27	licoresse	when I "touch" this symbol with the cursor, emacs crashes
08:30	raek	AWizzArd: if you want to controll the "running" on a per-agent basis, you might want to let the agent keep track of it's own running-value
08:30	raek	like this: (def a (agent {:running true}))
08:30	raek	(send-off a assoc :running false)
08:31	raek	but then, all it's actions must eventually time out
08:31	raek	otherwise, the agent will never run the "stop action"
08:32	raek	I use this approach in an agent reading from a socket
08:45	AWizzArd	Btw, is there a way to exit a doseq before it traversed its collection(s)?
08:47	LauJensen	AWizzArd, you mean like :when or :while ?
08:58	AWizzArd	LauJensen: good thx
09:00	LauJensen	np
09:06	ambient	does there exist a profiler in clojure that can identify which functions take how much time in the entire program execution?
09:06	LauJensen	I know JSwat does that, but I also think you can get it from jvisualvm
09:07	ambient	hmm, i thought that basic java profilers couldn't tell about defn funcs
09:07	LauJensen	if you followed by brians transient brain blogpost, you'll see future, deref, filter, concat etc all show up
09:08	liwp	ambient: each clojure function compiles into a java class with a bunch of invoke methods, so those should definitely show up
09:08	ambient	ok, thanks
09:08	liwp	seems like LauJensen has actually tried this ;-)
09:10	ambient	im super lazy, i think i need to do my own lib that i can just (use clojure.profiler) and (profile foobar) :p
09:11	liwp	that would be nic
09:11	liwp	nice even
09:11	LauJensen	c.c.profile aint doing it for you?
09:11	ambient	umm
09:11	ambient	there are plenty of things i'm unaware of
09:12	LauJensen	http://blog.bestinclass.dk/index.php/2009/10/brians-transient-brain/
09:12	LauJensen	read the last comment
09:13	ambient	great :)
09:14	liwp	seems like you have to annotate your code when you use c.c.profiling which is a bit icky
09:14	liwp	OTOH I guess you get more control that way and you can concentrate on those bits of the code that you want to work on
09:16	LauJensen	Everythings a trade in some regard
09:17	ambient	unless you steal and cheat
09:17	LauJensen	hehe
09:17	LauJensen	trade your soul for a gold watch
09:17	ambient	that actually holds true for programming also
09:18	ambient	you dont actually have to implement _the_ algorithm. just implement _an_ algorithm that _looks like_ the original one
09:18	ambient	when it comes to human interaction
09:20	ambient	low-pass filter with clojure: (reductions #(/ (+ %1 %2)) (oscillator))
09:21	ambient	* (/ (+ %1 %2) 2)
09:25	ambient	(defn lo-pass [d coll] (reductions #(+ (* %2 d) (* %1 (- 1.0 d))) coll))
09:25	ambient	this is just so amazing...
09:26	raek	ambient: that's beautiful
09:31	churib	/help
09:31	ankou	I'm using a function, that defines a macro, does this also work with aot-compilation? Or is macroexpansiontime with aot-compilation completly at compiletime?
09:32	chouser	unless you call compile or eval, no macros will be expanded after AOT
09:34	raek	ambient: do you have a repository for your synth project?
09:37	raek	I want to try your code...
09:37	ambient	raek: http://bitbucket.org/amb/clojure-snippets/src/tip/audio.clj
09:37	ambient	it's just in my random-code folder, might make a separate project if it grows larger
09:39	raek	bitbucket looks an awfully lot like github...
09:40	raek	I like github, so that's good, I guess
09:50	LauJensen	raek, Gitorious is the best though
09:52	noidi	what advantages does it have over github?
09:52	LauJensen	Speed, Speed and a consitent use of markup across the site. It's more community-oriented
09:55	noidi	hmm.. those merge requests with a status flag look handy
09:55	LauJensen	On ClojureQL we use the merge-request system to do code-reviews
10:29	octe	when writing code that is inherently stateful, for example an irc client, how would one structure that?
10:29	octe	in an oo-language you'd create a stateful object containing the socket connection, etc
10:29	octe	i've started a bit by creating a struct that holds those stateful objects, with a connect-function that creates it and returns it
10:29	octe	then define the other functions to take it as a parameter
10:29	octe	is that a good design?
10:32	arbscht	octe: interesting coincidence. that's -exactly- what I'm working on right now, and pretty much with the same approach
10:33	octe	maybe i'm on the right track then :)
10:34	octe	arbscht: exactly as an irc-client too, or rather just the same issue?
10:34	arbscht	irc client
10:34	octe	ah
10:34	octe	it's usually a good learning project..
10:35	arbscht	I suppose. I just got sick of pircbot :)
10:35	drewr	arbscht: that's what drove me to it too :-)
10:35	chouser	i've done a couple of these stateful connection-oriented things now, and they all look pretty much like this.
10:35	chouser	I suppose it's inevitable.
10:36	arbscht	the pattern shows up in my Swing code, too
10:36	chouser	It's very easy, though, to let the statefulness and mutation leak into more of your code than necessary. Be viligent.
10:36	arbscht	drewr: what came of it? have you published a library?
10:37	drewr	arbscht: heh, I'd show you if github weren't down...
10:39	octe	drewr: perhaps you could link it anyways so i won't forget to check it out when it comes back up..
10:40	drewr	http://github.com/drewr/clot/tree/master
10:42	octe	thanks
10:42	drewr	experimenting with sockets and dynamic message dispatch
11:25	kefka	,(ns a)
11:25	clojurebot	nil
11:25	kefka	(def x 4)
11:25	kefka	,(def x 4)
11:25	clojurebot	DENIED
11:25	kefka	Ah, right.
11:25	octe	github back up..
11:25	clojurebot	http://github.com/richhickey/clojure/tree/master
11:26	kefka	So here's a question. If I create a namespace a with x bound to 4, then create a namespace b that uses a, then when I'm in b, x will resolve to 4. However, outside of b, b/x does not resolve to 4.
11:26	kefka	Why is this?
11:27	Chousuke	have you required the namespace?
11:28	kefka	it's not a file. Actually, I meant _refer_, not _use_
11:29	kefka	anyway, use is supposed to be require + refer, right?
11:30	Chousuke	hm
11:30	kefka	How do I do the Lisp-paste again? I'll show an example.
11:30	drewr	every time I use defnk I want it to be in core
11:30	Chousuke	lisppaste8: url
11:30	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
11:30	drewr	kotarak ftw
11:31	chouser	kefka: That is the designed behavior, so that your main app namespace isn't cluttered with names from secondary libs.
11:32	kefka	chouser: Got it. Thanks. That makes sense. So I guess combining multiple namespaces into one is bad form?
11:33	kefka	What I have is multiple files that usually should go together in one namespace.
11:33	kefka	The files are broken apart because they're large (1000+ loc).
11:33	chouser	ah, well, you can do that with 'load'
11:33	chouser	such as core.clj, core_proxy.clj, core_genclass.clj
11:37	kefka	Ok. We're trying to avoid loading a bunch of files, except when we want to (e.g. reloading clj files).
11:37	kefka	My understanding of the advantage of require/use is that things are only loaded once.
11:38	chouser	hm. Well, I think there's a thing in contrib that allows you to pass values along from one namespace to the next, but I'm not sure its use is recommended.
11:40	tomoj	immigrate?
11:40	chouser	that's the one.
11:41	chouser	I haven't used it.
11:41	kefka	Ok, thanks. I'll look into that.
11:41	chouser	There was a thread on the group recently where it sounded like a couple people who had in the past no longer use it because they didn't like how it behaved.
11:41	tomoj	it does weird things
11:42	tomoj	http://groups.google.com/group/compojure/browse_thread/thread/400aac94e536e633#
11:42	kefka	I guess it's just odd to me that x, when in b, resolves to something different than b/x when outside of b.
11:45	cemerick	is it right that proxy has no access to protected methods/members, and gen-class is the only available route?
11:46	chouser	cemerick: yes
11:46	chouser	cemerick: or reify
11:46	cemerick	reify isn't fully baked yet though, right?
11:47	chouser	yeah, the bridge method stuff isn't there, and it's all in a side branch. which is why I started with "yes" :-)
11:48	cemerick	is it planned on for the nebulous 1.1, or is it on the back burner for now?
11:48	chouser	iirc, it's the main feature defining 1.1
11:49	cemerick	yeah, that's what I thought. I didn't know if things had changed of late, though.
11:49	cemerick	I've been stupidly busy.
11:49	chouser	stupidly?
11:50	cemerick	Yeah...doing a lot of work treading water, or so it feels like.
11:50	chouser	bleh
12:02	octe	drewr: i found your use of agents interesting
12:02	rhickey	just to fill you all in, I've been actively looking at something like dynamic type classes for Clojure. This driven by concerns that reify will leave us with the same limitations Java has re: extensibility - you can't add interfaces to existing classes. So reify won't help the if/else stuff in RT to have the abstractions reach java things
12:02	rhickey	but dynamic type classes would
12:02	rhickey	they're not quite type classes, I've been calling them 'protocols'
12:04	leafw_	sounds like "interface".
12:05	rhickey	leafw_: abstractly yes, but that has a meaning already that includes some thing that protocols wouldn't - requires derivation (at type definition time), creates isA relationship, non-injectable
12:05	rhickey	a protocol could be extended to any class after the fact
12:05	rhickey	and wouldn't create an isA relationship
12:06	leafw_	I understand, the vocabulary is taken. The definition you gave is that of an interface, yet not a java interface (since yours would be injectable)
12:06	leafw_	the protocol as you want it is a formalized duck-typing then.
12:06	rhickey	leafw_: not at all, not match by name
12:07	leafw_	then I'll shut up and wait what you come up with.
12:07	chouser	rhickey: out of curiosity, is there a forum (presumably offline) where you discuss such things, or is this the first you've said it "aloud"?
12:07	rhickey	you'd need a (implement protocol aClass fns)
12:07	rhickey	chouser: first aloud
12:07	chouser	ok
12:08	chouser	thanks for sharing. :-)
12:08	rhickey	I'm still working out the dispatch design, but it will be really nice, definitely what I would want, protocols orthogonal to types
12:08	rhickey	could do a lot of what Haskell type classes do, but not all, since no inference and dynamic
12:09	cemerick	this is in addition to reify, or is reify's usage of interfaces a subset of protocols?
12:09	rhickey	cemerick: I'm still working out the relationship between a protocol and an interface - obviously having some connections to interfaces enables extension from Java
12:10	rhickey	but they are truly different in that protocols aren't types (except as an implementation detail)
12:11	rhickey	and protocols much more Clojure-centric in directly yielding callable fns, aa opposed to host-world .callable things
12:12	cemerick	Sounds nice.
12:12	cemerick	of course, insofar as that "implementation detail" is stable, protocols are a superset of interfaces
12:13	rhickey	so there would just be a protocol for Seqable and it would define clojure.core/seq
12:13	cemerick	(which has the pleasant characteristic of fitting into my head easily :-))
12:13	rhickey	and you could say (implement Seqable String ...)
12:13	lpetit	rhickey: just to be sure I'm not mistaken things, this really has nothing to do with the way Qi allows to create types, one other feature you were talking about some day ?
12:14	rhickey	and there would be no need for RT.seqFrom and all the conditionals there
12:14	lpetit	rhickey: is there literature that comes close to what you have in mind ?
12:14	rhickey	lpetit: not about types
12:15	rhickey	lpetit: you could get to protocols by looking at CL literature about generic functions and grouping them (there is no construct, but often desired), or from interface injection, or from Haskell type classes (think dynamic)
12:16	chouser	so clojure.core/seq would be a IFn created when the Seqable protocol is defined?
12:16	rhickey	the critical thing is that they support orthogonal extension in the type or function dimensions, without intrusion into existing stuff
12:16	rhickey	chouser: yes
12:16	lpetit	rhickey: OK. I remember discussions between you and someone which haven't shown up for a couple months on the ml , don't remember his name, but he was always talking with you about orthogonality of protocols v/s types, and he also wanted to port more or CLOS to multimethods (or as one of the "out-of-the-box" multimethods dispatching strategies)
12:16	chouser	sort of multimethods in batches.
12:17	rhickey	chouser: a little bit yes, with some restrictions (dispatch function built-in)
12:17	rhickey	but much easier than dealing with multiple multimethods, and yielding a proper abstraction in a set
12:17	chouser	yep, makes sense.
12:18	rhickey	I spent a lot of time thinking about this on my Denmark trip, just working out the gory details now
12:18	rhickey	but I am still focused on cinc, and what facilities the language should have to enable that. RT indicates reify is not enough
12:19	rhickey	adopting interfaces is easiest and most like the current impl, but could be not the best fit for Clojure (of course there will always be a way to implement interfaces)
12:20	rhickey	I really like moving away from isA as the only way to share abstractions
12:22	rhickey	I don't like the auto-adapter-wrapper technique of Scala implicits
12:22	cemerick	isn't this something that could be implemented with some sugar on multimethods?
12:22	ambient	how would i go about introducing side effects to a closed stream (lazy-seq)?
12:23	ambient	value stream from user-controlled swing slider
12:23	cemerick	(not as an actual impl strategy, just getting my head around it)
12:23	rhickey	cemerick: first pass might be just to try out the syntax etc, but no, there will be some heavy lifting under the hood for perf probably
12:25	rhickey	that's what Im working on now (dispatch strategy), with an eye towards perf and possibly leveraging JSR292
12:25	lpetit	rhickey: to say it differently (so that I can check I understand the basics), is it ok to start with "it's a way to group related multimethods together, a more structured way than to just place them together in their own namespace" ?
12:27	rhickey	lpetit: except they are only available/extensible as a set, have a fixed dispatch strategy, and possibly some relationship to an interface for extension via Java
12:28	lpetit	rhickey: ok, I can see the plus. If you can think of a design that can make it possible to also do some static analysis for IDEs :-) (ok in this case this would really resemble what java interfaces do, but java interfaces are not bad, AFAIK)
12:28	rhickey	it would provide a very clear option for people coming from OO wondering how to encode their abstractions
12:29	rhickey	I like interfaces except for isA and not being able to add them to existing things
12:30	lpetit	rhickey: ok, "not being able to add them to existing things", => the new "protocol" concept is a dynamic extension (a superset) to interfaces in this area, right ?
12:30	rhickey	perf a critical question, as interfaces are very fast. so there's the static/dynamic tension
12:31	rhickey	lpetit: they differe in critical ways, so not/super/subsets. Interfaces imply an isA relationship
12:31	lpetit	rhickey : one more time please on the "isA" issue = do you mean there will be no such thing ? I guess I still don't totally understand in this area (Ah, java background)
12:32	rhickey	when you implement Seqable for String that won't make a String a Seqable
12:32	rhickey	but String will implement the Seqable protocol
12:33	rhickey	i.e. code written to Seqable will work for Strings
12:33	cemerick	rhickey: are you really aiming to make protocol dispatch performance on par with interface dispatch?
12:33	rhickey	and all of the things I have to go into RT to do now you will be able to do yourselves
12:33	lpetit	rhickey: but that would make a String implement the Seqable protocol. No speaking about types, but about protocols/behaviours, can't a behaviour be defined as an extension to an already existing protocol (interfaces do that, and I don't see that as the same "isA" relationship as "extends" conveys for java classes)
12:34	rhickey	cemerick: probably not possible without JSR292, and not sure even then
12:34	cemerick	OK, that sounds sane. :-)
12:34	rhickey	cemerick: but it needs to be really fast if to be the base for Clojure's abstraction set
12:35	cemerick	Right.
12:36	rhickey	lpetit: I haven't decided on extending protocols, not sure there's as much need in a dynamic lang, since oyu can always just create another protocol and implement that, the only time you care is if asking - do you implement protocol Z? you'd like the answer to imply something about X and Y
12:36	lpetit	rhickey : this indeed would be awesome, if the core does this.
12:37	lpetit	rhickey: I mean, for such generic protocols as Seqable, ..., really awesome !
12:38	rhickey	I'm trying to eliminate the closed extension I had to do in RT, which falls out of the limitations of interfaces
12:38	cemerick	I can't say I have a use case for this right now. Maintaining RT can't be fun, but I worry about the implications (esp w.r.t. perf) of pushing RT stuff down into clojure.
12:39	cemerick	or, the skeptic's, anyway
12:40	rhickey	a Clojure encoding of the RT conditional logic would have identical perf, it has more to do with interfaces vs (more dynamic) protocols
12:40	rhickey	but I totally agree, needs to be well considered. I think the interface bridging might provide a way to get the best of both worlds
12:41	cemerick	I've no idea what "interface bridging" is, but that's OK. :-)
12:41	rhickey	cemerick: having an interface fall out of defprotocol
12:42	rhickey	an implementing that interface would sidestep the more involved dispatch
12:42	rhickey	and
12:43	Chousuke	would you be able to "map" protocols to arbitrary interfaces then? Like the C++ concept map idea.
12:43	cemerick	ah, indeed, back to my thinking of protocols as a superset. Sure, they aren't is-a, but if you can map protocols to a basket of interfaces, that might be good enough for fast dispatch.
12:43	rhickey	Chousuke: I don't know, not a priority. The point is to provide a Clojure abstraction mechanism. Interfaces are a host thing
12:44	Chousuke	right. The quest to define Clojure without any mention to Java :)
12:45	rhickey	cemerick: right, the point though is that you can't rely on and should never ask if x isA protocol, because not all implementations can be
12:45	cemerick	rhickey: aside from your distaste of is-a, is getting away from interfaces really necessary for cinc? What potential hosts don't have interfaces or something similar?
12:45	rhickey	cemerick: It would make me sad for cinc to have the if/else stuff from RT still
12:46	octe	what is cinc?
12:47	rhickey	it seems like a fixed set (Clojure's abstraction * Java's built-ins), but represents a bigger problem (the expression problem)
12:47	Chousuke	I suppose the gist of it is that if cinc were defined in terms of interfaces, it would limit any implementation to emulating interfaces, but if we use something more "Clojurey" at the high level, the implementation could then use interfaces, or whatever fits
12:47	rhickey	I've been banging my head against the expression problem my whole career, would love to be done with that.
12:47	cemerick	rhickey: I'll buy you a beer to make you happier, then. I'm just saying, it's really OK if the host platform needs a bit of a hairball underneath. I'm just offering a cost/benefit sanity-check here.
12:48	ambient	octe: clojure in clojure afaik
12:48	lpetit	octe: Clojure IN Clojure
12:48	rhickey	cemerick: the problem will reappear in large Clojure apps and libs, just like it does now in Java - ever get an API that says 'just derive from this' that you want to use with classes you don't control?
12:48	octe	oh, thanks
12:49	rhickey	if interfaces are the way Clojure users create abstractions, we'll have that problem, plus the dot-or-not dichotomy
12:49	cemerick	aren't multimethods (or perhaps some sugared multimethods) the answer there, especially for app-level stuff?
12:50	rhickey	cemerick: sure, this is just a multimethod variant, but consider how often people wish certain Clojure fns were multimethods
12:51	rhickey	they're not because they are interface + hand-switch based
12:52	lpetit	rhickey: so for example, with protocols, one would be able to make new "types" adaptable to the protocols really used on defns arguments ?
12:52	cow-orker	Is there a way to use unqualified symbols in a macro? I have (defmacro mkfoo [name] `(defn ~name [param#] (foobar param#))) and it works, but the argument list shown by (doc some-made-function) is quite ugly (gensym'd param)...
12:53	cow-orker	As this macro is only called at the toplevel in a ns i control I guess I don't have to worry about capture?
12:53	rhickey	lpetit: right, a protocol is an extensible fn set, much like a multimethod is an extensible fn
12:53	lpetit	cow-orker: explicitly specifying a :args entry to the attrs-map is generally what is done by people which build such macros
12:54	lpetit	too sad I must leave the chat now, bye all
12:56	lpetit	cow-orker: I guess capture should always be intentional, your macro could be encapsulated in a complex 'let some day ?
12:57	Chousuke	cow-orker: lpetit's advice is good. (defmacro mkfoo [name] `(defn foo [param#] {:arglists ~'([param])} ...) should work
12:57	cemerick	rhickey: IIUC, that sounds just a little scary, on its way to python monkey-patching or somesuch. The nice thing about multimethods is that the hierarchies are naturally safe (using namespaced keywords, etc), and your ill-conceived hierarchy can't touch mine. But if core fns are hierarchies, then someone adding a dispatch to + for [:plum :heat] to return :prune is going to get messy.
12:57	Chousuke	you can also do (defn foo [~'param] ...) but that's evil. :)
12:57	cemerick	s/hierarchies/multimethods
13:00	cow-orker	Chousuke: yes I just found that in some example code by SH. Thank :-)
13:00	rhickey	cemerick: it is definitely not monkey-patching, in that fns are namespaced. I'm not sure what you mean by fns being hierarchies
13:00	rhickey	protocol fns are namespaced
13:00	cemerick	yeah, I meant s/hierarchies/multimethods there
13:01	rhickey	so right now someone can extend seq to some bizarre thing by deriving from Seqable
13:01	cow-orker	As for evil.... I consider this macro to be an implementation detail for the ns.... but can I count on this behaviour in future versions?
13:01	rhickey	using proxy e.g.
13:02	rhickey	also, I doubt + will become a protocol
13:03	Chousuke	cow-orker: which behaviour do you mean?
13:04	Chousuke	cow-orker: the evil example will just capture the name "param" from its environment, so for example (let [param 2] (mkfoo somefoo (stuff-with param))) would not work as expected
13:06	cow-orker	that ~'sym works like that and is allow - that there won't be an effort to disallow this in the name of macro hygiene :-)
13:06	cow-orker	...allowed....
13:06	Chousuke	ah, yes.
13:06	Chousuke	of course.
13:07	Chousuke	there's no way to disallow it, actually.
13:07	Chousuke	without adding special logic to how ~ works. and even then you could find ways around it.
13:08	cow-orker	yes... I guess so... so, use it sparsely and responsibly :-)
13:08	Chousuke	variable capture can be useful when desired
13:09	Chousuke	with the clojure syntax-quote it's also easy to spot
13:09	Chousuke	~'foo looks ugly enough that it'll make people stop and think whether it's really the right thing to do.
13:13	serp_	does clojure have macros?
13:15	cow-orker	Chousuke: true. I hope I do the right thing... the functions I create are part of the API for the ns so I think the (doc) should be nice.
13:15	Chousuke	serp_: of course. it's a lisp after all :P
14:09	ambient	how would i make this into a lazy sequence modifier: "y[i] := a* x[i] + (1-a) * y[i-1]" where a is constant, y is new seq, x is old seq
14:09	ambient	with reductions it seems to be "y[i] := a * x[i] + (1-a) * x[i-1]"
14:09	ambient	manually with rec-seq?
14:10	chouser	reductions should be passing you your previous return value, the the previous input value
14:11	ambient	i think i have to read the source some more to actually get it
14:11	chouser	hm, not sure that's the easiest.
14:12	ambient	im dealing with algorithms where i need to have more than one items of history for both new-sequence and old-sequence
14:13	chouser	(reductions (fn [yi-1 xi] (+ (* a xi) (* (dec a) yi-1))) init-y y)
14:13	chouser	that ought to do it, I think.
14:14	ambient	i already had (reductions #(+ (* %2 d) (* %1 (- 1.0 d))) coll) but i was doubtful of its correctness
14:14	ambient	it sounds right but i can't be sure if it actually _is_ right
14:14	ambient	and that really bothers me
14:15	ambient	and this is the simplest algorithm i have...
14:15	tomoj	can't you test it out?
14:15	ambient	i already threw the correct function into trash
14:17	chouser	,(reductions + 10 (range 5 10))
14:17	clojurebot	(10 15 21 28 36 45)
14:18	tomoj	ambient: what kind of audio algorithm is that?
14:18	ambient	here's the other one. "y[i] := a * (y[i-1] + x[i] - x[i-1])"
14:18	ambient	low-pass iir filter
14:18	tomoj	just do reductions on (partitions 2 1) for that one, I think
14:22	tomoj	except.. what's y[0]?
14:22	ambient	head of new-sequence
14:22	ambient	hmm no, tail
14:23	ambient	what value it is, doesn't really matter
14:23	tomoj	well, I dunno, but
14:23	tomoj	,(reductions (fn [y [x1 x2]] (* 2 (+ y (- x1 x2)))) 0 (partition 2 1 [1 2 3 4 5 6]))
14:23	clojurebot	(0 -2 -6 -14 -30 -62)
14:26	ambient	[0.3 -0.1 0.9 0.95 0.7 -0.99] original seq ... [0.3 0.15 -0.05 0.5750000000000001 -5.551115123125783E-17] correct seq when a=0.5
14:26	ambient	,(reductions (fn [y [x1 x2]] (* 0.5 (+ y (- x1 x2)))) 0 (partition 2 1 [0.3 -0.1 0.9 0.95 0.7 -0.99]))
14:26	clojurebot	(0 0.2 -0.4 -0.22499999999999998 0.012500000000000011 0.85125)
14:28	ambient	there might be some errors in my "correct-seq" though
14:28	tomoj	your correct sequence has a different length than the original
14:29	ambient	it's because y[i-1] when i=0 is not defined
14:29	tomoj	I see, so you need to skip one
14:29	ambient	i can also use default values, like 0
14:30	ambient	it doesn't make a large difference in audio quality
14:31	tomoj	well you have to have some initial arbitraty y
14:32	tomoj	if y[-1] is not defined, then neither is y[0], and so on
14:32	tomoj	looks like you're saying y[0] = x[0]
14:32	ambient	i used to do C so i wasn't so particular about reading from obscure memory locations if the value had no significance ;)
14:33	ambient	(+ nil 1)
14:33	ambient	,(+ nil 1)
14:33	clojurebot	java.lang.NullPointerException
14:35	ambient	i can't tell the difference between the correct one and yours by ear
14:36	ambient	good enough ;)
14:36	ambient	thanks for the help
14:36	tomoj	good luck
14:36	tomoj	I can't figure out where that correct seq is coming from
14:36	ambient	http://paste.pocoo.org/show/144753/
14:42	ambient	next up: converting this https://ccrma.stanford.edu/courses/220b-winter-2003/lectures/9/examples/moog.lisp into lazy-sec ;(
14:55	hiredman	clojurebot: protocols?
14:55	clojurebot	Titim gan éirí ort.
14:55	hiredman	clojurebot: protocols is <reply>http://clojure-log.n01se.net/date/2009-10-13.html#12:02
14:55	clojurebot	c'est bon!
15:04	lpetit	rhickey: currently multimethods have the insanely powerful property of being able to do multiple (and even more, arbitrary) dispatch on the arguments. What about protocols ? All these considerations of protocols being compared to java interfaces leaves me perplex. Is protocol a grouping of functions with a dispatch restricted to the first argument, as are java interfaces ? I guess there's a...
15:04	lpetit	...piece of the puzzle that's still missing in my head ...
15:06	chouser	lpetit: yeah, he said protocols would not have customizable dispatch function
15:06	rhickey	but might allow dispatch on other than the first arg
15:07	rhickey	multimethods will still be there for more advanced things, but protocols are likely to be simpler for others
15:08	lpetit	rhickey: do you have some "surface" example of what coding to protocols could look like ?
15:09	rhickey	lpetit: not that I want to share just yet, but would look like gen-interface with less cruft
15:10	lpetit	rhickey: ok, and the restriction on the dispatching mechanism certainly will make it just work with the concept of 'type, I guess ?
15:11	rhickey	(defprotocol Seqable [coll] (seq [coll] "Returns a seq on the collection"))
15:12	rhickey	lpetit: the interaction with type is something I'm still thinking about, including making type a more proper slot like meta
15:14	lpetit	rhickey: is using a capital letter as the first letter of the protocol name a convention suggestion, or is it just to make the parallel with the current java type name ?
15:14	rhickey	(implement Seqable [String] (seq [s] (StringSeq/create s))
15:15	rhickey	lpetit: dunno right now
15:16	lpetit	rhickey: wouldn't using a name like implement break the convention of prefixing such things with 'def: defmulti/defmethod ?
15:16	chouser	implement isn't interning any new name in the namespace like the other defs
15:16	chouser	that was done with defprotocol
15:17	lpetit	chouser: does defmethod intern a new name in the namespace ?
15:17	chouser	nope
15:17	chouser	good point.
15:17	chouser	then again, I tend to trip over that :-)
15:17	rhickey	don't worry about the names just yet, will be easier once there are semantics :)
15:18	lpetit	chouser: but maybe it's defmethod which breaks the convention, given your arguments :)
15:18	chouser	I have to think of both defmulti and defmethod before I can remember which to use for which.
15:18	LauJensen	rhickey, Is there a wiki entry coming up on assembla on this ?
15:19	lpetit	rhickey: thanks for all the input. I think I'll now refrain myself from asking more, and wait for something more elaborate on your part (and by not asking more questions myself I'll leave you some time to do so ;-) )
15:22	rhickey	LauJensen: not yet, needs more think-time
15:36	itistoday	anyone here used compojure?
15:36	itistoday	used or uses actually
15:41	LauJensen	Yea, all the time, its great :)
15:43	mwoelker	Here's a minimal prototype base "type system" for clojure: http://gist.github.com/209477
15:43	itistoday	LauJensen: what happens if you want to change a file? do you have to restart the server to recompile and load it?
15:43	mwoelker	I hope it's not considered heresy to put objects into a functional language...
15:44	mwoelker	Has anyone ever tried something like this?
15:44	opqdonut	hehe
15:44	opqdonut	have you heard of haskell, ocaml
15:44	LauJensen	itistoday, if you're working locally, usually you just re-eval whatever function your working on, at changes are immediate. On my server I don't have a live repl, so I change the file and restart
15:44	opqdonut	they are strongly typed functional languages
15:45	hiredman	that's not a type system
15:45	hiredman	that there is an "object" system
15:45	itistoday	LauJensen: (i'm new to clojure) do you get the repl the same way you get the repl to a running clojure program, by running it with a property to connect on a port?
15:45	kotarak	mwoelker: ocaml has objects ("Objective" Caml)
15:46	hiredman	mwoelker: don't do it
15:46	mwoelker	I meant specifically for clojure...
15:47	LauJensen	itistoday, you start a repl as you normally would, hopefully M-x slime, then you define your servlet and eval (run-server servlet params), that'll leave you with a repl and a running server
15:47	hiredman	what you have is the most naive way to implement objects
15:47	Chousuke	mwoelker: your mutate function is badly named :)
15:47	itistoday	LauJensen: but i mean if you're running this on a remote server
15:48	LauJensen	on a remote server I don't keep open repls
15:48	mwoelker	hiredman: I thought it might be a nice way to get some polymorphism in there, but maybe I'm just still to stuck in my OO ways
15:48	hiredman	there is a spinoza
15:48	Chousuke	mwoelker: it mutates nothing. (which is a good thing)
15:48	hiredman	but spinoze is also a mistake
15:48	hiredman	mwoelker: multimethods
15:49	Chousuke	polymorphism doesn't imply object-orientation
15:49	mwoelker	Chousuke: yeah I am not quite happy with the mutate name or implementation really
15:49	mwoelker	hiredman: multimethods have global effects don't they?
15:49	hiredman	mwoelker: global effects?
15:51	mwoelker	hiredman: well if I defmethod to handle vectors for instance, all future calls are gonna call that method, this approach allows only local effects
15:51	mwoelker	Asked another way what would the example code look like in idiomatic clojure?
15:52	Chousuke	(def a {:given-name "John" :surname "von Neumann"}), similarly for b :P
15:53	mwoelker	i.e. two pieces of "data/stuff" that should somehow behave differently
15:53	hiredman	mwoelker: it depends on your dispatch function
15:53	mwoelker	Chousuke: okay and full-name?
15:53	Chousuke	maybe with a :name-classification 'hungarian key as well
15:55	lpetit	mwoelker: hello!
15:55	Chousuke	then just (defmulti full-name :name-classification) (defmethod full-name 'hungarian [thing] (str (:surname thing) " " (:given-name thing)))
15:56	lpetit	mwoelker: from now on, have you already read through defmulti/defmethod, or is it a new are for you ?
15:56	lpetit	mwoelker: I found some detail (and some documentation parts) not easy to follow on, but the intent of defmulti is really super-powerful
15:57	Chousuke	mwoelker: Clojure generally doesn't use camelcase btw.
15:57	Chousuke	so identifiers like fullName are nonidiomatic
15:57	Chousuke	except when dealing with Java interop.
15:57	mwoelker	or is my premise wrong: mixing data and behaviour?
15:57	lpetit	Chousuke: is your use of 'hungarian rather than e.g. ::hungarian intentional ?
15:58	Chousuke	lpetit: hmm, good point. no. :)
15:58	lpetit	mwoelker: yes, it's wrong
15:58	chouser	if you really want to attach functions to your data (ala javascript prototypes), idiomatic use of multimethods isn't going to get you all the way there.
15:58	Chousuke	lpetit: I just thought I should use something other than a keyword
15:58	chouser	is it wrong? have you looked at clojure.zip?
15:58	Chousuke	if you want to attach functions to your data, do so, but don't make so big a deal over it.
15:59	Chousuke	after all, functions are just another kind of data.
15:59	mwoelker	sorry afkphonecall
15:59	lpetit	Chousuke: but I can understand - currently using raw keywords has its pro, but one big cons is that you're not helped at all with typos. In other areas the clojure compiler already does a good job of informing you (e.g. var symbols)
16:01	lpetit	of course data must be manipulated somewhere :)
16:02	mwoelker	I'm back, I still think the defmulti approach is somehow less clean and functional
16:02	lpetit	mwoelker: can you explain ?
16:03	mwoelker	the key keyword approach has the advantage that it adds a layer of indirection between caller and callee
16:03	lpetit	mwoelker: did you miss the recent IRC discussion on protocols, initiated by rhickey ?
16:03	mwoelker	lpetit: yeah I missed the protocols, was aware of multimethods though
16:04	mwoelker	with the prototype approach you could replace plain data with functions and vice versa
16:04	chouser	clojure.zip's implementation is relevent here.
16:04	lpetit	mwoelker: I'm not sure : the key keyword should be a matter of the library provider, something that "tags" the object when created -> so the caller would certainly prefer to use a builder function anyway :)
16:04	hiredman	lpetit: if he doesn't like multimethods, I doubt he will be interested it protocols
16:04	hiredman	and protocols don't exist yet
16:04	chouser	it manipulates vectors, each of which has a bunch of fns in its metadata
16:04	hiredman	so I don't think bringing them up is helpful
16:05	lpetit	chouser: can you elaborate, I don't know the implementation of clojure.zip very well
16:05	chouser	most of the public api fns simply turn around and call functions stored in the vector's metadata
16:05	Chousuke	chouser: do you think that was a successful approach?
16:05	mwoelker	no I do think multimethods have their uses, but I think in cases like these a different approach might be more viable...
16:05	hiredman	nope
16:06	mwoelker	I actually think protocols might be what I am looking for
16:06	chouser	Chousuke: well, it's immutable, extensible, and seems to have lived up well under a fair amount of use.
16:06	lpetit	hiredman: you seem to have strong thoughts, can you elaborate a little bit more in your answers ?
16:06	hiredman	if you reall want objects I recomend something like http://gist.github.com/209514
16:06	kotarak	chouser: in which way is this better than a multimethod?
16:07	lpetit	chouser: (real question, I don't have the answer) Had he had protocols at the time, would Rich have implemented clojure.zip with them ?
16:07	hiredman	lpetit: protocols apear to be a specialization/optimization on multimethods
16:07	chouser	kotarak: it probably predates multimethods :-P but besides that, it's just a different solution to similar problems.
16:07	lpetit	mwoelker: yes, protocols will give atomicity and cohesion to a set of multimethods
16:08	mwoelker	lpetit: anywhere I can read up on them?
16:09	lpetit	hiredman: not just a specialization, protocol have the added property of grouping multimethods. But a specialization in the sense that they will be (apparently, and certainly with performance and uniformity in mind) less open in the dispatching area
16:09	chouser	lpetit: I don't know, but it would seem reasonable. Had he had protocols he would have implemented much of RT and core in them, too. :-)
16:09	hiredman	handing people things that don't exist is not cool
16:09	Chousuke	mwoelker: scroll up your backlog :)
16:09	Chousuke	mwoelker: protocols don't exist yet and anything anyone says about them is subject to change
16:09	lpetit	clojurebot: protocols
16:09	clojurebot	http://clojure-log.n01se.net/date/2009-10-13.html#12:02
16:09	Chousuke	even the name :P
16:09	kotarak	chouser: yeah, there are a lot of relics in Clojure, like .. (double-dot). I would prefer a simple multimethods approach over a (maybe overly) clever metadata approach.
16:09	lpetit	mwoelker: clojurebot is your best spy/friend :)
16:11	hiredman	clojurebot: what does the world need?
16:11	clojurebot	what the world needs is more higher order functions
16:11	chouser	mwoelker: it seems likely to me that there are use cases where something like clojure.zip's approach, or one like javascript's prototype "inheritence", might fit better than anything else that is more commonly used in Clojure.
16:12	mwoelker	clojurebot: what is the meaning of liff?
16:12	clojurebot	Huh?
16:12	mwoelker	almost
16:12	lpetit	hiredman: I guess mwoelker is on the learning curve, and not trying to solve a real problem at hand, that's why I point him to "topnotch" stuff :)
16:12	chouser	I think one of the features of Clojure (and maybe lisps in general) is that they allow you to easily experiment with alternate solutions to problems like this.
16:13	chouser	if you can write three functions and suddenly have a new design option, why not try it out?
16:14	chouser	don't expect everyone else to start using it of course, but it if makes your life easier then by all means...
16:14	chouser	actually, lots of dynamic languages provide that feature to some level or other.
16:14	mwoelker	lpetit: Learning curve indeed.
16:15	lpetit	chouser: good point. lisps indeed are about freedom. I should not have said "it's wrong". I should have said : it may be a smell that you're trying to reproduce something from your java background. You may miss a better (or more functional or more idiomatic) solution by doing so. But in the end of the day it's only mwoelker who knows his problem domain best.
16:15	lpetit	chouser: thank you for reminding us to be modest. (I mean it, really)
16:15	chouser	mwoelker: if you're not yet comfortable with multimethods, I would recommend working with them a bit more.
16:15	Chousuke	macros are still my favourite feature of lisp
16:15	hiredman	woa, who is being modest?
16:16	Chousuke	you don't need them all that often really but when you do you'll be very grateful of them :P
16:16	chouser	lpetit: yes, of course you're right as well -- it's easy to reach for what you know and miss something that might be better.
16:16	Chousuke	or rather, when you'd need them in other languages you'll go "graah" and then resign to your fate.
16:17	Chousuke	OR start writing some code-generating preprocessor.
16:17	chouser	mwoelker: multimethods split apart objects type, type inheritence, object data, and behvaior in a way that provides you a lot of power and flexibility.
16:18	Chousuke	also you can dispatch on more than the object's type
16:18	Chousuke	how about the types of all the parameters, for instance?
16:18	hiredman	well
16:18	hiredman	java does that
16:18	chouser	Chousuke: that's why I listed behavior and object type separately. :-)
16:18	mwoelker	chouser: it's not really that I feel uncomfortablle with them, I just think they solve a different problem. To solve "my problem" with multimethods would mean annotating the data with extra markers so the multimethod can figure out what actual function to call. "Storing" the function in "slots" in the object itself allows for IMHO a neater solution while also sidestepping possible naming collisions
16:18	Chousuke	(and not the object itself :P)
16:19	hiredman	http://www.sics.se/~joe/bluetail/vol1/v1_oo.html <-- "Why OO Sucks"
16:19	rstehwien	chousuke: I learned ANTLR and read code generation in action because of parts of languages that made me go "graah". ActionScript does that to me daily
16:19	lpetit	mwoelker: I currently like to think about it as this from less abstract to more abstract: defn -> higher order functions -> multimethods. But indeed I recon I would still be annoyed if I had to do plain "database driven" programming with clojure. Though in database-driven code I've seen in the past (I mean java code), domain graphs generally were very anemic, and the business functions were...
16:19	lpetit	...methods of "static" (or singleton) service layer classes.
16:20	rstehwien	chousuke: so I do Clojure (and ruby) on the side to feel better
16:20	lpetit	mwoelker: of course this was a pity, but it was the reality of what I saw.
16:20	chouser	mwoelker: one of the trade-offs there is that multimethods allow others to add methods on your "types" without touching your objects
16:20	ambient	how do i make (map + [[1 2] [2 4]]) into (map + [1 2] [2 4])?
16:20	hiredman	ambient: apply
16:21	ambient	i've used map too much that i try to now do everything with it :p ty
16:21	rstehwien	chouser: I really like multimethods... maybe too much (sometimes an if statement will do).
16:21	chouser	rstehwien: heh.
16:21	rstehwien	chouser: next up is abuse of macros :)
16:23	chouser	rstehwien: you're allowed to abuse macros as much as you want as long as you never ask for help.
16:25	mwoelker	lpetit: maybe I am looking at it up from too much of an encapsulation and abstraction standpoint
16:25	mwoelker	lpetit: I blame years of C++ and Java ;)
16:27	ambient	how can i know in which line in my source code a runtime error happens?
16:27	raek	(.printStackTrace *e) might be useful...
16:27	kotarak	ambient: look for "caused by" lines. The stacktrace of the bottom one, is near the culprit.
16:27	ambient	raek nil
16:27	chouser	hm... without mutation of something you can't change the behavior of a whole class of existing objects. multimethods keep that mutation at the namespace and (one step down ) at the multimethod.
16:28	kotarak	ambient: look also in clojure.stracktrace/print-cause-trace
16:28	chouser	to do that with prototypes would require mutation at each object that might be used as a prototype, right?
16:28	raek	(doc *e)
16:28	clojurebot	"; bound in a repl thread to the most recent exception caught by the repl"
16:29	raek	ambient: or did it occur in an agent?
16:29	raek	in that case you'll want (agent-errors my-agent)
16:29	raek	and then (clear-agent-errors my-agent)
16:30	ambient	i have nothing but functions inside functoins at the moment
16:30	mwoelker	chouser: well you could do it as far up in the prototype hierarchy as required
16:30	ambient	raek emacs C-c C-k
16:30	mwoelker	chouser: of course this would not work at runtime which may or may not be a good thing
16:31	raek	ambient: I think I use "the other" emacs mode
16:31	raek	C-c C-k is not bound for me
16:31	mwoelker	chouser: of course you can always add another layer of indirection
16:33	hiredman	clojurebot: literal [0] problem
16:33	clojurebot	<reply>"There is no problem in computer programming which cannot be solved by an added level of indirection." -- Dr Maurice Wilkes
16:35	lpetit	hiredman: what did you mean by "java does that" ?
16:36	hiredman	lpetit: java dispatchs on object type and argument type
16:38	lpetit	mwoelker: I also have the samel feeling, something along those lines = If I use clojure on a big project, and follow what 'seems' to be the convention to just use keywords on maps as the sole way to access data slots, wouldn't I, at some point of the project, face a wall for not having encapsulating the slot access ?
16:38	lpetit	s/encapsulating/encapsulated/
16:39	lpetit	hiredman: I don't think so ? java dispatches on object type at runtime, but it does not dispatch on argument type at runtime. This one is the stuff of the compiler, isn't it ?
16:39	lpetit	hiredman: that's why there are books and blog posts about the Visitor pattern, when you can do that so easily with multimethods in clojure or generic functions in CLOS ?
16:40	mwoelker	lpetit: not only big projects, libraries as well. This might be a neat way to hide implementation details (like: is this value stored or computed) and allow for producers of library to perform updates while staying backward compatible
16:41	hiredman	lpetit: in java a method that takes a String is different from a method that takes an Integer
16:42	hiredman	so, void add (String a) {} and void add (Integer i) {}
16:42	lpetit	hiredman: but the choice of calling void add (String a) {} or void add (Integer i) {} is done at compilation time.
16:42	mwoelker	hiredman: yeah but which method gets called is decided at compile time
16:43	hiredman	so?
16:43	hiredman	it's still selected via the argument types
16:43	mwoelker	the thing is if you only have an Object at hand (which may be either an Integer or a String) the compiler will complain
16:43	mwoelker	Object=Object reference
16:43	lpetit	hiredman: so if you have A extends B and in a class void something(A a) [} and void something(B b) {} the compiler will choose the method not on the real dynamic type of the arg that is passed, but based on the declared type of the variable definition of the argument that is passed
16:44	hiredman	so?
16:45	hiredman	dispatch is still via argument type
16:45	lpetit	hiredman: so argument dispatch is not available at runtime in java.
16:45	hiredman	static, dynamic, whichever
16:45	lpetit	hiredman: the difference is big
16:45	hiredman	13:42 hiredman : lpetit: java dispatchs on object type and argument type
16:46	hiredman	I understand that the difference is big
16:46	hiredman	but the fact remains, java dispatches on object type and argument type
16:47	lpetit	hiredman: if you want, I'm bored by this no-end discussion, and it's late here, so 'night
16:48	lpetit	hiredman: but still, I consider the discussion was not about compilation dispatch, but really about runtime dispatch. You're playing with words
16:49	hiredman	well, nice of him to leave
16:50	hiredman	~botsnack
16:50	clojurebot	thanks; that was delicious. (nom nom nom)
16:52	ambient	if d is a sequence this gets a bit difficult: (reductions (fn [y [x1 x2]] (* d (+ y (- x1 x2)))) 0 (partition 2 1 coll)))
16:53	hiredman	(apply * (+ y (- x1 x2)) d)
16:54	hiredman	(reduce * (+ y (- x1 x2)) d)
16:54	hiredman	etc
16:54	ambient	it's all lazy
16:54	hiredman	well, * is not lazy
16:54	ambient	that's why it gets difficult
19:12	Dawgmatix	whats the recommended way to parse xml in clojure ?
19:17	hiredman	Dawgmatix: clojure.xml/parse
19:17	Dawgmatix	cool thanks :)
19:22	Dawgmatix	is there someway to modify the classpath from the slime repl ?
19:22	clojurebot	classpath is (System/getProperty "java.class.path")
19:23	hiredman	Dawgmatix: there is add-classpath, but it is best not to get into the habit of using it
19:23	Dawgmatix	i am coming from a lisp background and just trying to wrap my head around what the development cycle looks like for clojure
19:24	piccolino	Is there something like a 1.0 release of clojure-contrib?
19:24	hiredman	repl -> repl -> repl -> repl -> repl -> store -> repl
19:24	hiredman	there is a 1.0 compat branch of contrib
19:25	piccolino	But doesn't that change as development happens?
19:25	Dawgmatix	So if i want to use something like compojure, i add the directory to my actual classpath ?
19:25	Dawgmatix	(in my ~/.bashrc ? )
19:25	hiredman	piccolino: yes
19:25	hiredman	Dawgmatix: depends
19:26	hiredman	my classpath is "/home/kpd/*.jars"
19:26	hiredman	er
19:26	hiredman	my classpath is "/home/kpd/.jars/*"
19:26	piccolino	Hm. I'm trying to make a portfile for clojure-contrib, but I think I need some sort of zip file I can download for it (total macports amateur, though).
19:26	Dawgmatix	is there a startup file that clojure reads that I can use to set classpaths and do random other inits (for example (use ... ) statements)
19:27	hiredman	by the time clojure loads, the jvm is already running
19:27	hiredman	you can use some kind of script or what have you
19:27	Dawgmatix	oic - and the classpath isnt thought of as a dynamically changeable entity ?
19:28	hiredman	classpaths are, I belive, a property of ClassLoaders
19:28	Dawgmatix	(sorry if these are dumb questions, i am as much a java noob as i am a clojure one)
19:28	hiredman	and you cannot muck with the system classloader, you can do stuff like spin off your own classloader, but that can lead to issues
19:29	Dawgmatix	i see, so in short its better off to just have a jar folder like yours
19:29	hiredman	technomancy has some setup where he just unpacks the jar files
19:29	hiredman	shrug
19:30	hiredman	the jar directory approach has some issues to, classpaths with wildcards like only work with 1.6+ jvms
19:30	hiredman	but you can always just write a bit of code to generate a classpath from a bunch of jar files
19:31	hiredman	you can also do CLASSPATH="./libs/*" which is hand for a project specific classpath
19:31	Dawgmatix	I see.
20:29	froog	is there a unit testing framework that is still in active development?
20:36	jhawk28	junit?
20:36	jhawk28	define active development
20:37	chouser	froog: clojure.test is in clojure proper now, and all clojure's own tests us it
20:38	chouser	used to be test-is
20:41	Dawgmatix	is there any documentation for compojure ? i cant seem to find any on github ?
20:42	froog	jhawk28: it's just that fact states: "no longer in active dev", so that doesn't seem like the right tool to start using :)
20:42	Dawgmatix	alternatively are there other competing web frameworks ?
20:43	froog	chouser: thanks, will look into it
20:44	jhawk28	froog: junit is stable and doesnt need active dev (they did just release 4.7 in august)
20:45	froog	jhawk28: I thought that was for java
20:46	chouser	froog: I have a set of test written in clojure for junit so that they can plug into the junit runner suite at work.
20:47	mrowe	Dawgmatix: there's also conjure, which is pretty much a line-by-line clones of Rails
20:48	mrowe	Dawgmatix: and I believe there's a newer one, cascade, but I don't know anything about it
20:48	Dawgmatix	I see.
20:50	chouser	how much framework do you want? I'm using (a small part of) ring and like it very much so far.
20:50	Dawgmatix	I just want basic url routing
20:51	froog	chouser: ok, I just wanted something simple, but maybe junit is simple.
20:51	mrowe	Dawgmatix: sounds like compjure is what you want... there's a draft tutorial on the mailing list that should help get you started
20:52	mrowe	Dawgmatix: http://groups.google.com/group/compojure/browse_thread/thread/3c507da23540da6e
20:52	Dawgmatix	thanks :)
20:53	chouser	froog: I'd recommend you look at clojure.test. I mentioned junit only because it can be used, but it's a bit of a pain -- worth it only if using it buys you something else (like integration)
20:53	froog	jhawk28: thanks for pointing out junit.
20:53	chouser	ring and multimethod gets you very simple url routing. very simple
20:58	froog	chouser: yes, clojure.test looks very much like what I want
22:57	tomoj	maybe something is wrong with my brain. I can't figure out how to convert a char to a byte/int/whatever so I can do bit-test on it
22:57	hiredman	,(int \a)
22:57	clojurebot	97
22:57	hiredman	,(-> \a int byte)
22:57	clojurebot	97
22:57	tomoj	ah
22:57	tomoj	,(byte \a)
22:57	clojurebot	java.lang.ClassCastException: java.lang.Character cannot be cast to java.lang.Number
22:57	tomoj	why doesn't that work?
22:58	tomoj	chars are too big I guess?
22:58	hiredman	a Character cannot be cast to a Number
22:58	hiredman	nah
22:58	hiredman	I am pretty sure chars can be cast to ints no problem
22:58	clojurebot	People have a problem and think "Hey! I'll use a regular expression!". Now they have two problems....
22:58	hiredman	clojurebot: everybody!
22:58	clojurebot	everybody looks good in a sheinhardt
22:58	tomoj	yep, just not bytes
22:58	hiredman	well, and int can be cast to a byte
22:59	tomoj	right, but why not straight to byte?
22:59	hiredman	the issue is, bascially, boxing
22:59	tomoj	ah well, int will work fine for me anyway
23:00	tomoj	thanks
23:03	danlarkin	<3 30 rock
23:04	hiredman	:D
23:10	tomoj	this is profoundly ugly :( http://gist.github.com/223d4f377d4b3e7d6dab
23:10	tomoj	maybe I need to stop coding and go to sleep
23:11	tomoj	problem is to convert a (positive) integer to a big-endian two's complement string, so you have to add a 0x00 char if the leftmost bit is 1, and for 0 you're supposed to return 0x00, not just ""
23:11	hiredman	:(
23:12	tomoj	I wonder why the hell they use two's complement when all the integers are positive
23:12	tomoj	maybe btwoc is a standard function elsewhere?
23:12	hiredman	hmmm
23:13	hiredman	,(.getBytes "foo")
23:13	clojurebot	#<byte[] [B@265e47>
23:13	danlarkin	,(seq (.getBytes "foo"))
23:13	clojurebot	(102 111 111)
23:13	hiredman	,(-> "foo" .getBytes ((partial map int)))
23:13	clojurebot	(102 111 111)
23:14	danlarkin	I like mine
23:14	danlarkin	:-p
23:14	tomoj	that's backwards
23:14	hiredman	,(-> "foo" .getBytes ((partial map int)) ((partial map #(Integer/toBinaryString %))))
23:14	clojurebot	("1100110" "1101111" "1101111")
23:15	tomoj	though I'll have to do that eventually too
23:15	hiredman	,(-> "foo" .getBytes ((partial map #(Integer/toBinaryString %))))
23:15	clojurebot	("1100110" "1101111" "1101111")
23:18	danlarkin	,(map #(Integer/toBinaryString %) (.getBytes "foo")
23:18	clojurebot	EOF while reading
23:19	danlarkin	,(map #(Integer/toBinaryString %) (.getBytes "foo"))
23:19	clojurebot	("1100110" "1101111" "1101111")
23:19	hiredman	:(
23:19	danlarkin	so much less complicated
23:19	hiredman	parens are not complicated
23:20	hiredman	actually
23:20	hiredman	,(->> "foo" .getBytes (map #(Integer/toBinaryString %)))
23:20	clojurebot	("1100110" "1101111" "1101111")
23:20	hiredman	:D
23:31	durka42	(doc ->>)
23:31	clojurebot	"([x form] [x form & more]); Threads the expr through the forms. Inserts x as the last item in the first form, making a list of it if it is not a list already. If there are more forms, inserts the first form as the last item in second form, etc."
23:31	durka42	(doc ->)
23:31	clojurebot	"([x form] [x form & more]); Threads the expr through the forms. Inserts x as the second item in the first form, making a list of it if it is not a list already. If there are more forms, inserts the first form as the second item in second form, etc."
23:41	tomoj	i uinai mi manci na'e jimpe la'oi ->> doi durka
23:44	durka42	tomoj: clojure does that :)
23:45	durka42	it makes sense when you look at what hiredman gave ->> as an alternative to
23:45	tomoj	I will have to play around with it sometime
23:47	durka42	i hadn't seen ->> before, is it in the standard core or is it a clojurebot original (tm)?
23:47	hiredman	it was added to the core sometime is last month or so
23:49	rboyd	what's that operator called? arrow operator?
23:53	arbscht_	-> and ->> are 'threading'
23:54	hiredman	'awesome'
23:54	arbscht_	:)
23:54	hiredman	also the thrush combinator