#clojure – 2011-02-21

2011-02-21

02:25	amalloy	DespiteItAll: i was thinking of writing a twenty-questions program for my first foray into clojure web programming
04:35	rata_	what's the recommended way to generate json strings?
04:43	ejackson	c.c.json ?
04:44	ejackson	rata_: I've used it for a while no w/o problem
04:44	rata_	ejackson: ok =) thanks
04:44	rata_	I had heard about clj-json too, but I'll better go with contrib
04:48	ejackson	contrib is a solid choice
05:14	e-user	hi all
05:19	e-user	anyone with experience running clojureclr on mono here?
07:25	Dranik	is there anything like prolog for clojure?
07:30	Fossi	Dranik: logos
07:30	Fossi	google would've found that as well i guess
07:32	Dranik	Fossi, thanks
07:51	edoloughlin	https://gist.github.com/837007 — don't understand why my dispatcher doesn't work for []
07:57	edoloughlin	… or any arg, for that matter.
08:58	TimMc	DespiteItAll: Write a flatmate contracts website, where people click radio buttons to agree to certain standard options ("Pots and pans [do]/[don't] go through the dishwasher") and then agree to it by verifying an email sent to each person.
08:59	TimMc	DespiteItAll: There, now you have a website to write that involves user interaction, input validation, a database, and email sending.
09:01	charliekilo	Stupid question: (def x 2) (eval '(+ x 1)) works while (eval (let [y 3] '(+ y 1))) does not. Why?
09:03	TimMc	,(let [y 3] '(+ y 1))
09:03	clojurebot	(+ y 1)
09:03	TimMc	,(let [y 3] (eval '(+ y 1)))
09:03	clojurebot	DENIED
09:03	charliekilo	Sorry I meant (let [y 3] (eval '(+ y 1)))
09:03	TimMc	Ooh, clojurebot doesn't like eval.
09:04	charliekilo	My REPL doesn't either ;): java.lang.Exception: Unable to resolve symbol: y in this context
09:04	TimMc	In that case, I don't know the answer.
09:05	charliekilo	I got it to work with (eval '(let [y 3] (+ y 1)))
09:05	charliekilo	but thats not what I want
09:06	TimMc	Hmmm... I bet this has to do with symbols -> vars stuff, and let not introducing var bindings.
09:06	TimMc	...but that's beyond my knowledge, really.
09:07	TimMc	In any event, what are you trying to do? Seems like you want quasiquoting instead.
09:10	e-user	anyone with experience running clojureclr on mono?
09:21	fliebel	morning
09:21	mids	hoi
09:41	fliebel	Not directly Clojure related, but anyway… The Reasoned Schemer mentioned that NAND is a universal binary relation. All other relations can de defined by it. Does such a relation exist for >binary?
09:45	fliebel	So, a sensible relation for(for example) a trinary(0, 1 2) number, that can be used to define all other relations, and eventually half-adders and such. If there are non, I'm going to invent them :) (ouch, I hope I'm not saying impossible things now)
09:58	dnolen	fliebel: is the any-o issue fixed for you?
09:59	fliebel	dnolen: I havn't tried yet, I've been away the whole weekend. I did read a lot on TRS though.
10:00	fliebel	dnolen: I'm still intrigued by the number stuff. I can see why it would be slow, but I like it.
10:00	dnolen	fliebel: nice. well let me know how it goes and if anything else crops up.
10:00	fliebel	sure :)
10:00	dnolen	fliebel: it's very beautiful. all sort of arithmetic relationships appear like magic :)
10:01	fliebel	dnolen: I've been thinking about moving the numbers from binary relations to decimal relations. I'm not sure if it's even possible, or fast(er), but it's an interesting exercise.
10:03	fliebel	dnolen: I think it would be useful to have some debug option in Logos, to see how many unifications are done for a result.
10:04	Cozey	Hello. Ring passes body to response.getOutputStream. I want to pass a result of XSLT transformation which itself requires an OutputStream. Can I somehow short-circut these? Or do I need to first get a whole output of transformation and then return it as string body to ring. seems inefficient.
10:05	dnolen	fliebel: yes, that would be very useful, still thinking about how to properly implement debugging facilities. A bit tricky since the whole thing works with lazy sequences.
10:06	fliebel	dnolen: If I implemented that number stuff, would you want it for Logos, or do I just keep that to myself?
10:08	dnolen	fliebel: I would definitely consider it. Keep me posted on how it goes.
10:09	fliebel	dnolen: Great :) I'll start out by converting the stuff from the book to Clojure, and then I plan to see if I can make it any more efficient. I haven't studied computer science though ;)
10:12	fliebel	(was the any-o bug really fixed in one line?)
10:13	dnolen	fliebel: only a couple lines. The issue was simple, reduce is not lazy, I replaced it with mplus-concat which is lazy.
10:13	Cozey	hmm answering myself: looks like a job for piped streams of java's
10:17	Cozey	dnolen: wow! this plotter idea is absolutely fantastic!
10:18	dnolen	Cozey: plotter?
10:18	Cozey	isn't this Yours? http://www.formconstant.net/
10:18	dnolen	Cozey: heh, yes.
10:20	Cozey	as well as one drawing a day :-) hope that's working
10:20	dnolen	Cozey: haven't done much with recently. Got a bit into a Python implementation 2-3 years ago that I haven't touched since. That stuff is fun. Pen plotters are easy to come by and they use a brain dead simple ASCII serial protocol that's well documented.
10:20	Fossi	bit noisy on the console :)
10:21	dnolen	Cozey: also not so much recently, but hope to get back to that.
10:22	Cozey	will take a look at logos as well. . i was missing prolog
10:22	Cozey	are You using SLD or something more advanced?
10:23	dnolen	Cozey: there's quite a history of pen plotter artists, Vera Molnar is particular cool, http://www.veramolnar.com/diapo.php
10:23	Cozey	this is from a plotter?
10:23	Cozey	but not programmed I guess?
10:23	Cozey	ah, black and whites
10:23	angerman	What would be a good datastruction for a mesh to do subdivion on in clojure?
10:25	Cozey	so that's where the linear pictures come from
10:25	dnolen	Cozey: not that front image no. http://www.google.com/images?q=vera+molnar
10:26	dnolen	Cozey: not SLD, the algorithms from The Reasoned Schemer, but with Clojure changes for better performance.
10:28	Cozey	implementation discussed in the book is this "Kanren"?
10:29	Cozey	interesting :-) thanks :D
10:32	dnolen	Cozey: Kanren is an earlier implementation by Oleg Kiselyov. miniKanren is distillation of that work by Kiselyov, Daniel Freidman, and William Byrd.
10:33	kgrad5_	If i have an infinite sequence, let's say something like (iterate #(+ % 2) 1) how would I take all numbers less than some threshold? conceptually i want to do something like (take #(< % 1000) (iterate #(+ % 2) 1)) (i know that doesn't make sense)
10:33	gfrlog	take-while?
10:33	gfrlog	if they're sorted that will work
10:33	kgrad5_	oh sweet, thanks a lot gfrlog
10:33	gfrlog	,(take-while #(< % 100) (iterate #(+ % 2) 1))
10:33	clojurebot	(1 3 5 7 9 11 13 15 17 19 ...)
10:34	gfrlog	kgrad5_: no problem
10:36	chouser	whoever thought that bundling code and data together would promote code re-use was ... wrong.
10:38	chouser	I don't see any option other than (1) patch someone else's code (2) copy huge swaths of their code and make minor changes, or (3) use reflection hacks to work my will at runtime.
11:01	Munksgaard	I'm using cake to run a slime server with swank-clojure, but the connection keeps closing. I'm using clojure-1.3.0-alpha4 and swank-clojure-1.3.0-SNAPSHOT... Does anyone know how to get it working?
11:04	Munksgaard	i can evaluate nil in the slime REPL, but once i try to write (println "something") it closes the connection before i even get to the space
11:09	Munksgaard	and if i try to use an older version (clojure-1.2.0 and swank-clojure-1.2.0) it just hangs when i try to evaluate nil in the repl
11:15	tensai_cirno	hello guys. I'am experiencing problems with lein repl. It breaks after first error.
11:16	tensai_cirno	http://pastie.org/1589769
11:17	tensai_cirno	emacs swank mode just breaks after first whitespace in parenthesis
11:17	tensai_cirno	also Versions differ: 2010-06-04 (slime) vs. 20100404 (swank).
11:17	tensai_cirno	in emacs
11:17	tensai_cirno	ubuntu 10.10, emacs and slime from repo
11:22	Munksgaard	tensai_cirno: i've got the same problems
11:36	tensai_cirno	Munksgaard, got working slime
11:36	tensai_cirno	you need to install it from technomancy repos
11:36	tensai_cirno	https://github.com/technomancy/swank-clojure
11:36	tensai_cirno	there's section for emacs
11:36	tensai_cirno	and ':dev-dependencies [[swank-clojure "1.3.0-SNAPSHOT"]]' in project.clj
11:49	Munksgaard	tensai_cirno: ok, thanks
12:11	Cozey	what's the overhead of "future" ?
12:14	gfrlog	Cozey: seems to call clojure.lang.Agent/soloExecutor
12:15	Cozey	and then doing some thread pool magic... but what does it all mean? Is it really lightweight? so You can paralelize some things 'just because you can' or is it not worth it?
12:16	gfrlog	,(future 20)
12:16	clojurebot	#<core$future_call$reify__5500@404baf: :pending>
12:16	gfrlog	,(map deref (map #(future %) (range 10))
12:16	clojurebot	EOF while reading
12:16	gfrlog	,(map deref (map #(future %) (range 10)))
12:17	clojurebot	(0 1 2 3 4 5 6 7 8 9)
12:17	gfrlog	Cozey: no idea :)
12:17	gfrlog	performance test?
12:17	Cozey	it seems i would need to do that
12:17	gfrlog	or maybe somebody else will speak up
12:17	Cozey	but making benchmarks is quite a taunting task
12:17	gfrlog	just don't listen when tasks taunt you
12:18	gfrlog	they're only doing it because they're insecure themselves
12:20	gfrlog	maybe I shouldn't make fun of strangers
12:43	cdddr	If I do something like (call sorted-set some-seq), does it unwind the whole sequence at once, or process it one at a time?
12:48	AWizzArd	cdddr: it would have to calculate the hash of some-seq.
12:49	AWizzArd	some-seq is tested via the hash if it is one of the elements in your sorted-set.
12:50	cdddr	Uhh, my bad, I meant apply not call.
12:50	cdddr	I basically want to keep unique values from some-seq.
12:50	cdddr	Sorting is nice, but I can do it in another step.
12:51	gfrlog	cdddr: I'm watching tv and not paying attention, but does distinct help?
12:52	cdddr	gfrlog: Ah, yes.
12:53	cdddr	I'm still at the stage where I'm not sure what the stdlib can do. :(
12:53	gfrlog	easiest people to help :)
12:54	cdddr	Hahaha, right. It's better like this, though. I remember when I "learned" Python on my own, and then I needed to stick for like 3 months on #python to realise I was being ass-backwards about almost everything. :)
12:55	gfrlog	there are so many ways to write bad code...
12:55	cdddr	Yeah. I mean, reimplementing stdlib out of ignorance is bad, but I'd take that over, say, writing COBOL in Java anytime. ;)
12:56	gfrlog	the first option sounds a lot more fun
12:56	clizzin	anyone have any experience with parsing HTML in clojure/java? what's the best library to use?
12:57	raek	clizzin: enlive is very easy to use
12:57	raek	it uses tagsoup under the hood
12:57	clizzin	raek: enlive has functions specifically for parsing? i thought it was a templating library.
12:57	raek	it does that too... :)
12:57	cdddr	gfrlog: Oh, trust me. I've had the misfortune of actually seeing COBOL-in-Java. I almost cried.
12:58	clizzin	raek: interesting, shall check it out. thanks!
12:58	raek	dnolen made a tutorial that explains both the scraping and templating uses
12:59	raek	clizzin: minimal example (fetching the title of a page): https://github.com/raek/lcug-examples/blob/master/bot/src/se/raek/lcug/titlebot.clj
12:59	clizzin	raek: awesome, thanks! btw, any idea how it compares to https://github.com/getwoven/webmine? that's the other one i just remembered which might work well for parsing.
13:02	fceccon\|a	clizzin: check https://github.com/swannodette/enlive-tutorial
13:02	raek	clizzin: webmine seems to use tagsoup just like evlive, but looks much more specialized towards extraction (disclaimer: I haven't used webmine)
13:03	clizzin	raek, fceccon\|a: great, thanks for the thoughts and advice! i'll play around and see what works best for my use case.
13:31	charliekilo	Stupid question: (def x 2) (eval '(+ x 1)) works while (let [y 3] (eval '(+ y 1))) does not (java.lang.Exception: Unable to resolve symbol: y in this context) ... Why, oh why?
13:31	gfrlog	(doc eval)
13:31	clojurebot	DENIED
13:31	gfrlog	,(doc eval)
13:31	clojurebot	DENIED
13:31	gfrlog	dangit
13:32	gfrlog	I think eval is funny about local bindings
13:32	gfrlog	by which I guess I mean it ignores them
13:33	gfrlog	what do you get if you (def x 12) (let [x 13] (eval '(+ x)))
13:33	edoloughlin	Anyone got CCW content-assist for Clojure working? It only does Java for me
13:35	gfrlog	,(let [def 12] (+ def 5))
13:35	clojurebot	DENIED
13:37	charliekilo	13
13:37	charliekilo	since it sees the first x
13:37	gfrlog	wouldn't 13 mean it sees the second?
13:38	gfrlog	I get 12
13:38	charliekilo	oh, I thought you meant '(+ x 1) and just forgot the 1
13:38	gfrlog	ah; yeah I guess that was unnecessarily complex
13:38	gfrlog	so I would assume that eval just ignores all local 'variables'
13:39	gfrlog	apparently it does see binding; but that's probably not what you want to do
13:39	cdddr	Uhh, why would eval ignore the local bindings?
13:39	gfrlog	dunno...why wouldn't it?
13:40	TimMc	gfrlog: Because it is surprising.
13:40	gfrlog	that is a good reason.
13:40	cdddr	Yeah, and I don't see a good reason to ignore them.
13:40	gfrlog	I should retreat to "I don't know" then
13:41	gfrlog	maybe it's harder to execute...
13:41	TimMc	gfrlog: There is a difference between local let "bindings" and def'ined vars, but I don't know enough about Clojure to say anything further on the subject.
13:41	gfrlog	because the vars are all stored somewhere public, but the local lettings are probably much...slyer?
13:41	TimMc	I do know that let bindings are not mutable.
13:41	gfrlog	well they can be overridden
13:42	gfrlog	,(let [x 12] (let [x 15] x))
13:42	clojurebot	15
13:42	TimMc	Sure, but that's just scope.
13:42	gfrlog	yeah
13:42	gfrlog	I would think
13:42	gfrlog	that
13:42	charliekilo	let me ask another stupid question: is 'eval' the right function here?
13:42	gfrlog	lettings can be handled at compile time
13:42	TimMc	("just scope", he said, infuriating language designers everywhere)
13:42	charliekilo	or is there another one I should use?
13:42	gfrlog	but whatever goes into eval has to be handled at runtime
13:42	TimMc	charliekilo: What do you want to do?
13:43	raek	the lexical scope where eval is called is does not "span" into the evaled form
13:43	TimMc	charliekilo: I ask because you might be trying to reimplement defmacro or something.
13:43	gfrlog	raek: Is that a fancy restatement of "eval doesn't see local bindings"?
13:44	raek	gfrlog: pretty much. :)
13:44	charliekilo	TimMc: I am looking at SICP symbolic differentation and want to eval the resulting function with some value of x
13:44	gfrlog	okay, just making sure I understood
13:44	gfrlog	we were wondering why it would be that way
13:44	TimMc	from a language design standpoint, preferably
13:44	cdddr	You know what Clojure API docs could really use? "See also:" everywhere.
13:45	gfrlog	charliekilo: I'm wondering if macros can help
13:45	TimMc	cdddr: I tend to use clojuredocs.org
13:45	gfrlog	I assume the "don't write macros" mantra has an implicit "unless you would otherwise be using eval"
13:45	charliekilo	gfrlog: thats what I was thinking, but since I am not modifying executing order, it should be possible without it, right?!?
13:45	TimMc	gfrlog: Oooh... symbolic differentiation via macros? I'm getting all tingly.
13:46	cdddr	TimMc: Ooh, that's a gem.
13:46	gfrlog	maybe I should stop talking because I actually have no idea what "symbolic differentiation" means and TimMc makes me think that might be important
13:46	TimMc	cdddr: Blame gfrlog.
13:46	gfrlog	for the existence of a gem?
13:47	cdddr	Heh, I meant the clojuredocs site, but hey, that works, too. :)
13:47	TimMc	cdddr: Hah! OK.
13:47	gfrlog	none of the currently active conversations are not confusing me.
13:48	TimMc	charliekilo: If you were doing symbolic differentiation of hardcoded expressions, macros might be appropriate, as outrageous as that idea seems to me at the moment.
13:49	TimMc	However, I suspect you are receiving sexprs as arguments and wanting to differentiate and evaluate those.
13:49	TimMc	Quasiquote might help you, actually.
13:50	gfrlog	I was thinking of macros instead of evaling
13:50	gfrlog	i.e., for inserting the code
13:50	gfrlog	inside a (let)
13:50	charliekilo	TimMc: I will try, but it somehow does not feel right ... then again, I have not come up with a good solution either
13:50	gfrlog	now I'm second-guessing myself though
13:51	TimMc	(eval `(let [y 4] ~expr))
13:51	gfrlog	that was the next thing I started thinking about
13:51	gfrlog	so as long as that's not dependent on other local bindings...
13:52	gfrlog	and even if it is you can probably do (eval `(let [x ~x] ~expr))
13:52	raek	iirc, fogus made a library for these kind of things
13:52	TimMc	gfrlog: That was my thought as well.
13:53	charliekilo	hmm ... I guess I have to play around multiple options and see what looks nice in the flow of code
13:53	gfrlog	the only way to write readable code is with triply-nested macros.
13:54	raek	charliekilo: https://github.com/fogus/evalive
13:54	raek	example from the docs: (evil '{message "Hello", place "Cleveland"} '(println message place))
13:55	raek	looks like something that could accomplish what you are trying to do
13:55	cdddr	Ooh, Python-style eval. :)
13:55	charliekilo	raek: that looks like it will work ... I'll take a look .. thanks
14:15	TimMc	Any quick way to turn a seq of maps into a map of seqs?
14:16	brehaut	eg [{:a 1} {:a 2 :b 1} {:b 3}] {:a [1 2] :b [1]} ?
14:17	scottj	merge-with concat?
14:17	gfrlog	,(doc merge-with)
14:17	clojurebot	"([f & maps]); Returns a map that consists of the rest of the maps conj-ed onto the first. If a key occurs in more than one map, the mapping(s) from the latter (left-to-right) will be combined with t...
14:17	gfrlog	scottj: is that a question?
14:18	scottj	gfrlog: nm
14:18	brehaut	merge-with isnt quite right
14:18	gfrlog	now I'm wondering what a function called concat? would do
14:18	brehaut	merge-with will not call you fn if there is no conflict
14:18	gfrlog	scottj: sorry, I failed to notice the previous comments
14:19	TimMc	brehaut: I know these maps all contain the same keys.
14:19	TimMc	But no, merge-with wouldn't work.
14:19	gfrlog	TimMc: there's an easy way to do this
14:19	cdddr	brehaut: How so? You can specify your own key-combining function.
14:20	gfrlog	(map (apply juxt maps) ...) should be helpful
14:20	brehaut	cdddr: ##(merge-with (constantly :applied) {:a 1} {:b 2})
14:20	sexpbot	⟹ {:b 2, :a 1}
14:20	cdddr	brehaut: Ahh.
14:21	gfrlog	(into {} (map (juxt identity #(map (apply juxt maps) %)) (keys (first maps)))
14:21	gfrlog	maybe could clean that up with ->>
14:22	TimMc	I think I'll stick with a three-liner instead.
14:22	gfrlog	but juxt is fun!
14:22	TimMc	,(doc juxt)
14:22	clojurebot	"([f] [f g] [f g h] [f g h & fs]); Alpha - name subject to change. Takes a set of functions and returns a fn that is the juxtaposition of those fns. The returned fn takes a variable number of args, a...
14:23	gfrlog	(apply juxt maps) is a function that takes a key and returns a vector of the key's value in all the maps
14:23	TimMc	I kind of see where you are going with that.
14:23	gfrlog	the rest is just cruft for tying everything together into a map
14:24	gfrlog	I would think the (apply juxt maps) part would be useful no matter how you rearrange everything else
14:24	brehaut	gfrlog: are you sure that even runs?
14:25	gfrlog	nope :)
14:25	gfrlog	I'm sure that it would if I had a few rounds to debug it though
14:25	TimMc	These maps only have two keys, and I know them.
14:26	cdddr	TimMc: Give in to the dark side of premature abstraction! ;)
14:26	TimMc	(apply juxt my-maps) is a neat trick, but too complicated for this task.
14:26	gfrlog	maybe (let [vals-fn (apply juxt maps)] {:a (vals-fn :a), :b (vals-fn :b)})
14:26	brehaut	tim then its simple
14:26	cdddr	It's just like premature optimization, but with ore fun and mess. ;)
14:27	TimMc	cdddr: I might write a LoM->MoL fn.
14:27	TimMc	brehaut: Don't tell me I can destructure this thing...
14:27	brehaut	,
14:27	brehaut	(reduce #(merge-with conj %1 %2) {:a [] :b []} [{:a 1} {:b 2 :a 2} {:b 2}])
14:27	clojurebot	EOF while reading
14:27	gfrlog	mine had less :a's and :b's in it
14:28	brehaut	,(reduce #(merge-with conj %1 %2) {:a [] :b []} [{:a 1} {:b 2 :a 2} {:b 2}])
14:28	clojurebot	{:a [1 2], :b [2 2]}
14:28	gfrlog	oh nm
14:28	brehaut	yeah its not a 'general' solution
14:28	brehaut	even easier
14:28	brehaut	,(apply merge-with conj{:a [] :b []} [{:a 1} {:b 2 :a 2} {:b 2}])
14:28	clojurebot	{:a [1 2], :b [2 2]}
14:29	gfrlog	brehaut: I think I like it
14:29	TimMc	hm
14:30	gfrlog	making use of the good ole' conj{:a function
14:30	TimMc	After I finish making my tests pass, I'll see if I can wedge that in.
14:31	gfrlog	make a switch statement with a case for each possible number of maps that there could be
14:31	TimMc	Data structure dilemma!
14:32	TimMc	I'm traversing a DAG and picking up values. I don't want duplicates, but I want to preserve topological order.
14:32	brehaut	,(reduce (fn [a [k v]] (update-in a [k] (fnil conj []) v)) {} (mapcat (partial map identity) [{:a 1} {:b 2 :a 2} {:b 2}]))
14:32	clojurebot	{:b [2 2], :a [1 2]}
14:32	brehaut	a genera solution
14:32	gfrlog	okay now mine is better
14:33	TimMc	OK, that used two functions I don't know yet.
14:33	brehaut	gfrlog: really? mine runs :P
14:33	brehaut	upfate-in and fnil?
14:33	TimMc	mapcat and fnil
14:33	gfrlog	brehaut: That's cuz you have a higher draft standard for irc
14:33	TimMc	Oh man, mapcat is what I've been looking for for another thing.
14:34	TimMc	I had to write that once for some functional JS I was doing.
14:34	brehaut	TimMc: haha
14:34	brehaut	TimMc: for is often a more useful way of writing mapcat
14:35	cdddr	Woah, there's map-indexed? One less function in the chain.
14:37	gfrlog	,(let [maps [{:a 1 :b 2} {:a 2 :b 2}]] (into {} (map (juxt identity (apply juxt maps)) (keys (first maps)))))
14:37	clojurebot	{:a [1 2], :b [2 2]}
14:38	gfrlog	brehaut: I was assuming his all-maps-have-same-keys condition
14:38	brehaut	ok sure. cause otherwise you generate interstitial nils
14:38	gfrlog	and miss some of the keys if they aren't in the first map
14:40	TimMc	That would be the equivalent of a ragged 2D array.
14:40	brehaut	TimMc: vector of vectors is the obvious one
14:40	brehaut	or a map of vectors
14:40	TimMc	Heh, I guess what I'm basically doing is a transpose.
14:40	brehaut	depends on your keys
14:43	brehaut	TimMc: if you have a vector of vectors, and you want to transpose its just ##(apply map vector [[1 2 3] [4 5 6]])
14:43	sexpbot	⟹ ([1 4] [2 5] [3 6])
14:44	TimMc	$findfn [1 2 1 2 4 1] [1 2 4]
14:44	sexpbot	[clojure.core/distinct]
14:45	TimMc	oooh
14:45	gfrlog	I was trying to figure out how to do $findfn just the other day... digging through the sexpbot source and no luck
14:55	amalloy	gfrlog: it's in sexpbot.plugins.clojure
14:55	amalloy	near the bottom somewhere
14:55	gfrlog	amalloy: must have missed it. I was looking at exactly that.
14:56	gfrlog	I only skimmed the source, so I don't think I actually gleaned any info at all
14:56	gfrlog	I was hoping it'd be full of (def-thing-you-can-type "$findfn" ...)
14:58	amalloy	gfrlog: it is! if you search for "findfn" you find what you want immediately
14:58	amalloy	(not $findfn, because the command prefix is configurable)
15:00	amalloy	gfrlog: https://github.com/Raynes/sexpbot/blob/master/src/sexpbot/plugins/clojure.clj#L156
15:01	gfrlog	hmmm
15:01	gfrlog	since I didn't know it was called "findfn" I'm not sure if that would have jumped out
15:01	gfrlog	but I should clarify that I don't at all mean to criticize the code.
15:04	amalloy	gfrlog: sure? i do so enjoy sulking after being maligned
15:05	gfrlog	amalloy: absolutely -- I would have been shocked if the information had been accessible within the amount of effort I was willing to put in
15:05	amalloy	lol
15:05	gfrlog	then I would have written you a personal physical letter of thanks with a five dollar bill in it.
15:07	amalloy	the basic concept of findfn took a couple hours and a dozen lines, but all the tweaking necessary to deal with sandboxing and such makes it a huge mess
15:08	amalloy	$findfn [1] 1
15:08	sexpbot	[clojure.core/last clojure.core/count clojure.core/peek clojure.core/first clojure.core/rand-nth]
15:08	amalloy	i always get a laugh when rand-nth makes it into the answer list
15:09	cdddr	amalloy: It only tries the core functions, right?
15:09	amalloy	cdddr: https://github.com/Raynes/sexpbot/blob/master/src/sexpbot/plugins/clojure.clj#L146
15:09	amalloy	$findfn "test" 2 "te"
15:09	sexpbot	[]
15:09	amalloy	hm
15:10	cdddr	Ooh.
15:10	amalloy	$findfn 2 "test" "te"
15:10	sexpbot	[clojure.contrib.string/butlast clojure.contrib.string/take]
15:10	Cozey	$findfn (fn [a b] a) 2
15:10	sexpbot	[]
15:10	Cozey	any way to get functions arity?
15:10	amalloy	Cozey: that is not an easy problem
15:10	Cozey	I know :-)
15:10	amalloy	someone posted a hacky solution to the google group months ago
15:11	amalloy	Cozey: http://groups.google.com/group/clojure/browse_thread/thread/d9953ada48068d78/1823e56ffba50dbb
15:28	jweiss_	looking for the simplest fn that will return a different value every time it is called
15:28	jweiss_	(i just care that the values are not equal and don't have isa? relationship)
15:29	scottj	jweiss_: gensym?
15:29	jweiss_	scottj: ah good call
15:45	cinch	jweiss_: (str (java.util.UUID/randomUUID))
15:47	clizzin	is there a way to use apply when you're calling a java method on a variable-length vector of arguments?
15:48	amalloy	clizzin: not really. what's your usage scenario?
15:48	amalloy	cinch: that's not guaranteed to be different, though of course the odds are...somewhat in favor :P
15:49	clizzin	amalloy: i'm using clojure to wrap a java method. the clojure method takes a variable-length list of arguments at the end, and i wanted to just use apply to call various versions of the java method that take different numbers of arguments
15:50	amalloy	clizzin: the current "best" way to do it is manually, i think. you can hack something up with clojure.lang.Reflector if you want
15:50	clizzin	amalloy: alright, thanks for the info
15:50	cdddr	$findfn [1 2 3] [4 5] [1 2 3 4 5]
15:50	sexpbot	[clojure.set/union clojure.core/lazy-cat clojure.core/concat clojure.core/into]
15:52	amalloy	cdddr: into is the least-awful of those options
15:56	cdddr	amalloy: Yeah, but I'm doing something like (set (concat A B)), so I think concat actually fits better.
15:56	amalloy	cdddr: (into (set A) B)?
15:57	amalloy	&(into (set [1 2 4 5 2]) [5 7])
15:57	sexpbot	⟹ #{1 2 4 5 7}
15:57	cdddr	Oooh.
15:57	drobati	I'm trying to use slime for the first time and slime-repl isn't showing up when i slime-connect
15:57	cdddr	Although it feels weird somehow.
15:57	drobati	I installed slime not from packages.el
15:58	amalloy	cdddr: or (set/union (set A) (set B)) if you like
15:58	brehaut	&(use 'clojure.set)
15:58	sexpbot	⟹ nil
15:58	brehaut	amalloy: i dont think b needs to be a set for union
15:58	amalloy	brehaut: it doesn't, but that's an impl detail
15:58	brehaut	(union #{1 2 3} [1 3])
15:58	brehaut	amalloy: sure
15:59	amalloy	might even be better for performance to make them both sets, if A were large and distinct, and B were like [1 1 1 1 1 1 ...]
16:01	kjeldahl	drobati: Do you have swank-clojure installed?
16:01	cdddr	x (map println (take 10 some-var)) inside a let... I'm going to debugging hell,
16:01	gfrlog	cdddr: I don't think (map println ...) normally does much
16:02	drobati	I have a dev-dependency in project.clj "1.2.1"
16:02	drobati	kjeldahl: I use lein swank.
16:02	cdddr	gfrlog: Hence the take except I lied, I'm doing (count (map... :)
16:02	gfrlog	cdddr: oh okay
16:03	cdddr	My initial, even more clueless version was (drop-while (constantly true)...
16:03	gfrlog	,(drop-while (constantly true) (repeat "haha"))
16:03	kjeldahl	drobati: swank-clojure.el is an emacs package. On github. I know nothing about lein swank.
16:03	clojurebot	Execution Timed Out
16:04	drobati	kjeldahl: lein installs swank-clojure from github for me.
16:05	kjeldahl	drobati: It installs an emacs package for you? You're way ahead of me then..
16:05	drobati	Wait. Not an emacs package.
16:06	kjeldahl	It's emacs support you're struggling with, right?
16:06	drobati	I believe so.
16:06	amalloy	cdddr: (filter #{} some-var) :P
16:06	drobati	The swank server seems to work.
16:06	drobati	But no repl is showing up.
16:06	scottj	what does slime-connect do?
16:06	kjeldahl	No repl inside Emacs you mean?
16:06	drobati	yes
16:06	drobati	Slime repl spits back a cute message.
16:07	drobati	But no repl (it opens slime-events though
16:07	drobati	)
16:07	scottj	what version of slime?
16:07	gfrlog	amalloy: (= (constantly true) (comp not #{}))
16:07	scottj	recent versions are not supported
16:07	gfrlog	man if you could compare functions like that we wouldn't need to write programs anymorj
16:08	drobati	scottj: I didn't know that.
16:08	drobati	I'm pulling from the official slime repo.
16:08	drobati	building and installing myself
16:09	semperos	drobati: try adding this to your .emacs
16:09	semperos	(slime-setup '(slime-repl))
16:09	drobati	I saw that before. Let me try it again but I think it was a bit quirky.
16:10	semperos	I had slime auto-starting my repl for me, and then "one day" it just stopped, and that solved it for me
16:10	scottj	go to slime commit 605f930a or oct 15 2009
16:10	drobati	should I eval that then rerun slime-connect
16:11	semperos	should do the trick
16:11	drobati	its up
16:11	semperos	great
16:11	drobati	Works!
16:11	drobati	is the swank repl prompt user>
16:11	ossareh	morning all
16:11	semperos	is for me
16:11	drobati	perfect
16:12	drobati	Thanks semperos, kjeldahl, and scottj
16:12	semperos	np, enjoy
16:12	drobati	Will do. :)
16:13	scottj	drobati: to use slime-fancy you'll need to use an older version of slime I think. http://www.youtube.com/emailataskcom to see some of the advanced slime features
16:14	drobati	thanks for the link
16:21	TimMc	Well, that yak looks pretty well shaved: https://github.com/timmc/CS4300-HW3/blob/master/src/timmcHW3/cascade.clj
16:21	TimMc	Now I can get back to my actual program. >_<
16:22	gfrlog	so if I'm implementing my own numeric type, I don't get to use the clojure.core/+ and such functions, right?
16:23	gfrlog	gotta use (defn add) and (defn multiply)?
16:24	Chousuke	you can define + and * in your own namespace too.
16:24	Chousuke	you just need to exclude the core ones
16:24	gfrlog	yeah, but then other namespaces making use of it can't...
16:24	Chousuke	can't what?
16:25	gfrlog	can't use the overridden functions
16:25	Chousuke	sure they can
16:25	Chousuke	all functions are namespaced
16:25	amalloy	gfrlog: c.c.generic-math
16:25	cnataren	is there a place where there are tasks that need to be done for clojure-clr?
16:25	Chousuke	what you can not do is augment the clojure arithmetic operators :/
16:25	gfrlog	Chousuke: and regardless, my implementations would need to use the core ones; so it'd be sticky
16:26	Chousuke	gfrlog: you can reimport them namespace-qualified, it's not that hard :)
16:26	Chousuke	the use them as core/+ etc.
16:26	gfrlog	yeah
16:26	gfrlog	is there some reason arithmetic isn't done as a protocol?
16:26	Chousuke	speed
16:26	stuartsierra	Does `lein test` run with dev-dependencies?
16:26	abedra	technomancy, is there a way to get "test" dependencies in lein?
16:27	Chousuke	also I guess JVM integration/historical reasons
16:27	gfrlog	stuartsierra: does for me I'm pretty sure
16:28	gfrlog	I'd say I'm completely sure, but I think you wrote a book about clojure or something, so that puts an upper limit on my sureness
16:28	stuartsierra	I wrote a book about Clojure, not lein.
16:28	gfrlog	I didn't write a book about lein
16:29	stuartsierra	And I don't intend to.
16:29	gfrlog	I infer from having written a book about clojure that you've used lein more than me
16:29	stuartsierra	No, I use Maven.
16:29	gfrlog	okay, my sureness is rising then
16:29	gfrlog	let's say I'm sure
16:31	gfrlog	amalloy: c.c.generic.math-functions seems to specifically exclude arithmetic... is there some reason the arithmetic functions weren't defined as multimethods in the first place?
16:31	abedra	gfrlog turns out it does
16:31	gfrlog	abedra: cool, thx
16:31	amalloy	gfrlog: sorry, i always get these two confused: http://richhickey.github.com/clojure-contrib/generic.arithmetic-api.html#clojure.contrib.generic.arithmetic/*
16:32	gfrlog	aw man I missed than 5 lines above the other one
16:32	gfrlog	the question still stands though
16:41	amalloy	gfrlog: performance
16:42	amalloy	multimethods would slow the bejeezus out of the huge majority of apps that don't need to override +
16:42	gfrlog	I guess clojure.core/+ can be redeffed manually anyhow, right? perhaps to the c.c.generic.arithmetic versions?
16:43	gfrlog	is that a disastrous idea?
16:45	brehaut	gfrlog: dont redefine it; refer-clojure :exclude it out of the way, and use :only the one from c.c.g.a
16:46	gfrlog	brehaut: yeah...I was thinking I'd get the benefit of the operators working anywhere in the app, but I guess being explicit is bester
16:47	gfrlog	and won't slow down random other libs that don't need it
16:47	brehaut	redefining this is pretty non-idiomatic clojure i think
16:47	brehaut	yup
16:50	gfrlog	,(let [do 12, if 19] (+ do if))
16:50	clojurebot	31
16:51	brehaut	ever looked at PL/1 ?
16:51	gfrlog	nope
16:51	brehaut	IF IF THEN THEN ELSE ELSE is approximately valid code
16:51	gfrlog	that sounds useful
16:51	brehaut	keywords were explicitly not reserved
16:52	brehaut	it was an early example of overengineering
16:52	brehaut	i think it might have had something to do with multics
16:53	amalloy	gfrlog: ##(let [do 10 if 40] (do if))
16:53	sexpbot	⟹ 40
16:54	gfrlog	amalloy: Okay what the heck.
16:54	amalloy	special forms are only special in the function position
16:55	gfrlog	and special forms are always special in the function position?
16:55	gfrlog	that's the part I didn't expect
16:55	amalloy	yes
16:55	amalloy	&(let [do 10 if 40] (if do 5))
16:55	sexpbot	⟹ 5
16:55	gfrlog	right
16:56	gfrlog	apparently you can't let reader macros though
16:57	amalloy	gfrlog: not sure what you mean, though either way you're right
16:57	gfrlog	I mean
16:57	gfrlog	,(let [' 15] (+ 489 '))
16:57	clojurebot	Unmatched delimiter: )
16:59	amalloy	i'm not sure that counts as a reader macro, but maybe. it doesn't seem surprising to me: you can't let [ as a local either
17:00	gfrlog	yeah I don't know what I was thinking really
17:00	gfrlog	amalloy: the clojure cheatsheet says it's a reader macro
17:00	gfrlog	and the clojure cheatsheet has never let me down
17:01	amalloy	okay. i thought the name "reader macro" was reserved for things starting with #, but i seem to be wrong
17:01	brehaut	more importantly i think http://clojure.org/reader calls it a reader macro too
17:02	gfrlog	I assumed that any syntax that wasn't parentheses was a reader macro
17:02	gfrlog	but they don't list map literal or set literals etc, so I'm confused
17:03	brehaut	gfrlog: a map literal becomes a map in the AST, a ' becomes a list
17:04	brehaut	excuse the fuzzy use of AST
17:04	gfrlog	brehaut: I would have expected that a map literal gets translated into a call to (hash-map)
17:04	gfrlog	maybe that's less efficient though
17:06	brehaut	gfrlog: but maps and vectors have meaning for evaluation, so you dont want to turn them into lists to be created at runtime
17:07	gfrlog	that is a terribly good point
17:07	brehaut	(again, sorry for the overly impress wording. im failing to express myself right)
17:07	nickik	Why not, works in CL :)
17:07	brehaut	man i fail at words today
17:08	gfrlog	since #{} is not a reader macro either, presumably we could use sets for stuff
17:08	brehaut	overly imprecise wording
17:08	gfrlog	,(let [#{a b} #{1 3}] (+ a b))
17:08	clojurebot	java.lang.Exception: Unsupported binding form: #{a b}
17:08	gfrlog	I support that binding form
17:08	brehaut	i dont think we need to get into a common lisp / clojure debate thanks all the same
17:09	gfrlog	(let [[a b] #{"I wish" "this worked"}] a)
17:09	gfrlog	,(let [[a b] #{"I wish" "this worked"}] a)
17:09	clojurebot	java.lang.UnsupportedOperationException: nth not supported on this type: PersistentHashSet
17:09	nickik	I didn't want a debate it was just a fun anecdot
17:09	gfrlog	nickik: While I see your point, I respectfully disagree.
17:10	amalloy	&(let [[a b] (seq #{"I wish" "this worked"})] a)
17:10	sexpbot	⟹ "this worked"
17:10	gfrlog	nevermind that statement was probably more confusing than funny
17:11	gfrlog	amalloy: Yep, that's what I ended up doing, all over my code...
17:12	brehaut	gfrlog: there is little to gain from using sets in forms though
17:12	brehaut	the binding form is a maybe
17:13	gfrlog	brehaut: I know. There's just fun.
17:13	gfrlog	add some randomness to which variable gets which value
17:13	brehaut	hah
17:13	brehaut	indeed
17:14	amalloy	it makes some sense for a sorted-set though
17:14	brehaut	amalloy: sure, but there is no literal, so it would be a bit awkward for forms
17:14	gfrlog	no literal _yet_
17:14	brehaut	hah
17:15	brehaut	#>{1 3 2}
17:15	gfrlog	I don't think that's beatable
17:15	TimMc	brehaut: Why not #<{1 2 3} ?
17:15	brehaut	why not indeed
17:15	brehaut	i think they are both less good than
17:15	brehaut	#{< 1 2 3} or #{> 1 2 3}
17:16	gfrlog	augh
17:16	TimMc	,>
17:16	clojurebot	#<core$_GT_ clojure.core$_GT_@1160709>
17:16	brehaut	and {> 1 :a 2 :b}
17:16	amalloy	brehaut: that form is evil
17:16	TimMc	brehaut: < is already a symbol
17:16	gfrlog	,(let [<{ "party-hat"] (println "I'm wearing my" <{))
17:16	clojurebot	Unmatched delimiter: ]
17:16	brehaut	TimMc: so is >
17:17	TimMc	brehaut: As in, having it inside the braces is ambiguous.
17:17	brehaut	so is outside
17:17	TimMc	,{< :a 1}
17:17	clojurebot	java.lang.RuntimeException: java.lang.ArrayIndexOutOfBoundsException: 3
17:17	brehaut	because then its not consistent with maps
17:17	brehaut	its ambigous for maps both ways
17:17	TimMc	Outside with a # in front, it isn't ambiguous.
17:18	gfrlog	we need a syntax for queues too
17:18	brehaut	and if the sorted-map and sorted-set literals arent consistent, someone would need to be punched in the throat
17:18	TimMc	Hmm, sorted map...
17:18	brehaut	,(sorted-map 1 :b 4: a :2 :d)
17:18	clojurebot	Invalid number: 4:
17:19	brehaut	hah whoops
17:19	brehaut	,(sorted-map 1 :b 4 :a 2 :d)
17:19	gfrlog	is not, I counted to 4: this morning
17:19	clojurebot	{1 :b, 2 :d, 4 :a}
17:19	gfrlog	oh man I think I've spent most of the day in irc
17:20	gfrlog	make sure you guys work out a syntax for finger trees too
17:20	brehaut	not everything needs a literal :P
17:22	amalloy	but brehaut, then how could anyone use my new racecar-type objects in a macro?
17:22	brehaut	amalloy: they can go use perl and write a text munging macro ;)
17:22	amalloy	#<==]blue should be added to clojure.core
17:22	amalloy	for rocket ships with colors
17:23	brehaut	i dont tihnk you should force one colorspace on the definittion of colors
17:23	nickik	Are finger trees going to be 1.3?
17:23	clojurebot	excusez-moi
17:24	brehaut	we need to be able to define colors using rgb, bgr, cymk, X,Y,Z, X',Y',Z', pantone and css
17:25	amalloy	brehaut: why stop there? let's add color gradients
17:26	brehaut	now i understand why CL extensible reader macros are a bad idea :P
17:32	jweiss_	i hate to bring this up, but the "Latest News" section at http://clojure.org is not new at all
17:33	jweiss_	I think the newest item there is 6 months old or more
17:33	brehaut	there is a new piece of clojure the language news?
17:34	jweiss_	i only mention it because there are people I'm trying to sell clojure to, they notice nothing changes there, and they tend to think the language is not thriving which is not true
17:34	jweiss_	brehaut: isn't there?
17:35	brehaut	'work continues on 1.3' every day is pretty uninformative news
17:35	brehaut	compare it to python.org/news/
17:36	brehaut	major releases, major cons, books about the language
17:36	brehaut	if you want to see the nitty gritty then dev.clojure.org is a hive of activity
17:37	Chousuke	the dev page doesn't look superactive either to be honest. I have no idea where all the stuff is happening.
17:38	jweiss_	brehaut: i guess i'm saying it's better to redefine "news" to include smaller items
17:38	jweiss_	than to have the page go untouched for so long
17:38	brehaut	jweiss_: personally i'd rather people worked on the language than the news page is all im saying
17:38	jweiss_	i agree - that's why i hated to bring it up.
17:39	jweiss_	maybe the news page is not necessary
17:39	jweiss_	i mean, what good is the announcement that 1.1 is released?
17:39	brehaut	if you want mroe noisy general community news, the ML, dev ML, planet.clojure.in, disclojure.org all provide a huge range of stuff
17:40	jweiss_	brehaut: i'm not saying this because i have difficulty finding news
17:40	jweiss_	there's plenty of other sources
17:40	brehaut	jweiss_: i just dont see how you could invent more news for clojure.org
17:40	jweiss_	i'm just saying that if the official site has a news section, it should contain actual news :)
17:40	jweiss_	not links that are 6 months to 2 years old
17:41	brehaut	so you would rather it was empty?
17:41	brehaut	or had one item
17:41	drobati	I'm not sure what I'm doing wrong with slime. But I've got a file that is connected to slime, with a -main in it. I've C-c C-k, but am failing to call the function in the repl.
17:41	jweiss_	yes. having it gathering dust like that is a little embarrassing for the language. makes it appear that it is not being actively worked on and used (even though that is not true)
17:41	drobati	I'm extremely new to this, so I know I'm doing something wrong.
17:42	jweiss_	brehaut: i don't want to be one to complain and not offer to help so i'd update the news section at least occasionally if someone let me :)
17:42	amalloy	drobati: is your repl prompt in the right namespace?
17:42	drobati	user>
17:42	drobati	do i have to apply a ns to it?
17:43	drobati	I've seen something about it somewhere.
17:43	drobati	I think in the videos someone linked me earlier.
17:46	amalloy	drobati: to call a function from your foo namespace, your repl should be in that namespace (with ns foo)
17:47	drobati	thanks
17:47	drobati	didn't understand that
17:50	raek	(in-ns 'the-ns) is safer than (ns the-ns), since it wont't auto-refer clojure.core vars
17:50	Stavros	hello!
17:51	Stavros	how can i retrieve the second-to-last element from a vector?
17:51	raek	(nth v (- (count v) 2)) ?
17:51	Stavros	oh, isn't there a sort of reverse-nth?
17:52	raek	well there is. (second (rseq v))
17:52	Stavros	i see, thanks
17:53	raek	traversing the vector backwards has linear time complexity
17:53	raek	nth is always constant time* for vectors
17:53	Stavros	i only want two elements, so that's fine
17:54	drobati	(in-ns 'name.space) worked. Thanks raek and amalloy.
17:55	raek	drobati: in case you use Emacs: you can press C-c M-p in the source buffer to switch to that namespace
17:55	drobati	Thank you for that binding.
17:55	amalloy	Stavros: ##(peek (pop [1 2 3 4 5]))
17:55	sexpbot	⟹ 4
17:56	Stavros	amalloy: ah, thanks
17:57	raek	the readme of swank-clojure lists many really useful bindings. I recommend trying them if you haven't seen them
18:02	drobati	raek: I think I glanced through it on github.
18:02	drobati	Well the bindings part.
18:33	brehaut	is there a function that takes a seq and a predicate and returns [(take-while s) (drop-while s)]
18:33	brehaut	and i forgot the pred in that expression
18:36	brehaut	its called span in haskell
18:37	dnolen	,(group-by even? [1 2 3 4 5 6 7 8 9 0])
18:37	clojurebot	{false [1 3 5 7 9], true [2 4 6 8 0]}
18:38	dnolen	brehaut: ^ ?
18:38	brehaut	dnolen: not quote
18:38	brehaut	(span even? [2 4 5 6 7 8]) -> [[2 4], [5 6 7 8]]
18:38	brehaut	hypothetically
18:40	sattvik	,(split-with #(< % 5) (range 10))
18:40	clojurebot	[(0 1 2 3 4) (5 6 7 8 9)]
18:40	danbell	,(split-with even? [2 4 5 6 7 8])
18:40	clojurebot	[(2 4) (5 6 7 8)]
18:40	brehaut	ah excellent. thanks!
18:50	danbell	anyone feeling charitable and want to explain to me why swank-clojure is both an elpa package and a lein plugin?
18:51	danbell	I'm 99% certain I'm confusing old blog posts with the current Way To Do Things
18:54	dnolen	danbell: I think swank-clojure in ELPA is just the machinery for the protocol, the client so to speak. the swank-clojure.jar is the server and it needs to be on the classpath of your current project. might be wrong tho.
18:54	danbell	dnolen: thx, but then what's slime for?
18:55	dnolen	SLIME is the mode.
18:55	danbell	ah
18:56	danbell	gotcha, thx
18:58	dnolen	danbell: http://bc.tech.coop/blog/081209.html, nice graphic describing the relationship.
19:00	danbell	where does clojure-mode fall in there?
19:03	dnolen	danbell: clojure-mode is just syntax-highlighting and indentation really.
19:03	danbell	ah
19:03	danbell	the pieces are falling into place
19:04	danbell	ok, thanks a lot
19:04	danbell	was banging my head there
19:04	dnolen	it's all pretty confusing. crazed Lispers.
20:34	amalloy	brehaut: split-with is definitely the way to go, but there's also http://clojuredocs.org/clojure_contrib/clojure.contrib.seq/separate if you want something slightly different
20:34	brehaut	amalloy: cheers
21:11	TimMc	I wrote a program state dependency manager that allows you to (lazily?) propagate recomputations through your application's state: https://github.com/timmc/CS4300-HW3/blob/master/src/timmcHW3/cascade.clj
21:12	TimMc	Basically, you give it a DAG with a "cleaner" function at each vertex. When you mark a node dirty, that propagates out to all dependant nodes, transitively.
21:14	TimMc	When you call clean on a node, it cleans all the dirty dependency nodes, then calls the node's own cleaner thunk (which does something in your app) and returns the new state with the nodes marked clean.
21:14	TimMc	1) Does anybody else find this useful or interesting? 2) If so, what should I call it?
21:15	amalloy	TimMc: sounds neat. i don't know what i'd find it useful for
21:15	TimMc	I wrote it for a graphics program.
21:16	TimMc	Use case: The user hits undo. Toolbar buttons need to be en/disabled, undo/redo menus change state, canvas is redrawn, etc.
21:16	amalloy	i wonder how you discover which nodes to call clean on. you can't call clean on the root node, because it has no dependents
21:16	TimMc	I got tired of debugging all these state recomputation cascades every time I added a feature.
21:17	TimMc	amalloy: https://github.com/timmc/CS4300-HW3/blob/master/src/timmcHW3/core.clj#L446 <-- I created an :all node that depends on :gui and :painting, each of which depends on several other things.
21:17	TimMc	So, you can have logical nodes that have nil cleaners.
21:18	TimMc	Checking if a given node is clean is pretty much a constant time operation.
21:20	brehaut	amalloy: the ? macro to the rescue
21:20	amalloy	brehaut: yeah?
21:20	brehaut	im debugging mess of a tokenizer
21:21	amalloy	yeah, debugging messes is the use case :P
21:21	brehaut	yes :)
21:26	TimMc	The ? macro?
21:26	amalloy	TimMc: something i gisted a while ago
21:27	brehaut	https://gist.github.com/c93c37345c49c47dcfa2
21:28	brehaut	what does it do ?
21:29	amalloy	brehaut: it's not a special operator or anything. it "just" quotes the result of unquoting (quote x)
21:29	brehaut	ohright
21:29	brehaut	haha
21:29	amalloy	&`[x '~'x]
21:29	sexpbot	⟹ [clojure.core/x (quote x)]
21:30	TimMc	I'm struggling to read this thing.
21:30	amalloy	i guess more apt would be ##`[x 'x '~'x]
21:30	sexpbot	⟹ [clojure.core/x (quote clojure.core/x) (quote x)]
21:30	TimMc	I need to play with macroexpand-1 a bit.
21:32	TimMc	'~' = quote unquote quote?
21:32	amalloy	yeah
21:33	TimMc	So that's... (quote (unquote (quote x)))
21:33	amalloy	ie, it's the same as ', except that you want to leave the syntax-quoting context and enter a regular-quoting context
21:33	brehaut	amalloy: you'll be happy to know i resisted the urge to use regexps to write this parser
21:36	joshua__	Is it possible to execute another Clojure program from within a Clojure program? I have a list of items in a queue and a program for processing that list of items. I have a separate program which adds items to the queue and I want to give that program the ability to say, "process the queue if it not already being processed."
21:37	joshua__	One way to handle this that I've considered is making a cron script that runs the first program every few minutes.
21:38	joshua__	(note the processing is scraping a website, the separate program is a website that allows you to add items to the queue)
21:38	brehaut	joshua__: why is the consumer not blocking on reading the queue
21:39	joshua__	brehaut, I don't understand?
21:39	brehaut	joshua__: are you familiar with the idea of blocking?
21:40	amalloy	joshua__: he suggests having the processing program always be in "processing mode", and wait if there's nothing to do
21:40	joshua__	Oh... I hadn't even considered that options. That sounds like the way to do it.
21:41	joshua__	brehaut, my understanding of blocking is that it means that one program can't reach the resources that another program is using.. am I way off?
21:41	amalloy	joshua__: yeah, you are
21:41	joshua__	Goes off to read wikipedia, unless you guys have better links.. yeay learning
21:42	amalloy	i'm having a surprisingly hard time finding a good link
21:42	joshua__	Oo. I think I was confusing blocking with locking..
21:44	amalloy	joshua__: amusingly, the best i could do is an msdn article: http://msdn.microsoft.com/en-us/library/aa365683%28v=vs.85%29.aspx
21:50	amalloy	ah, or http://www.makelinux.net/ldd3/chp-6-sect-2.shtml
21:53	TimMc	amalloy: I don't think I'm ready to understand the inner workings of macro expansion, namespaces, and symbols yet. I'll leave that ? macro for when I am.
21:54	amalloy	TimMc: wise words
21:54	brehaut	amalloy: want a code improving challenge?
21:54	amalloy	oh noes. sure
21:54	brehaut	hah
21:54	brehaut	https://github.com/brehaut/ring/blob/master/ring-core/src/ring/middleware/accept.clj
21:54	brehaut	its a tokenizer for the spec of 14.1 of http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.41
21:55	amalloy	brehaut: s/seperat/separate. am i done yet? :)
21:55	brehaut	hah you dont have to do anything
21:56	brehaut	but yse, i cannot spell
21:56	amalloy	(def token-char? (complement illegal))
21:56	brehaut	hah yes
22:00	joshua__	Alright, so blocking basically means that you put a thread to sleep until some event occurs that lets you know you can now deal.
22:00	brehaut	joshua__: effectively, but you shouldnt be putting the thread to sleep yourself
22:01	joshua__	brehaut, alright, how would you put it to sleep if your not allowed to put it to sleep yourself?
22:02	brehaut	your queue should implement a blocking read
22:02	amalloy	joshua__: ##(read)
22:02	sexpbot	java.lang.Exception: EOF while reading
22:02	brehaut	you jsut read from the queue
22:02	amalloy	i'd drop the cond in quoted-string and try to combine the (recur) clauses into one since they're pretty similar, plus lift some of the repetition into an enclosing let; make it more like (if (empty? ...) [..] (let [next (ffirst cs) tail (drop 2 cs)] ...))
22:03	brehaut	joshua__: in clojure, lots of reference types implement blocking on deref, eg (def p (promise)) (doto (Thread. (fn [] (Thread/sleep 3000) (deliver p 1))) .start) @p
22:04	brehaut	run those three in a repl one at a time
22:04	brehaut	@p should pause for a couple of seconds and then return 1
22:04	brehaut	thats because the promise blocks until it has a value delivered to it
22:04	brehaut	amalloy: sure that makes sense
22:05	amalloy	joshua__: you read from streams (java or c++) all the time, right? like sockets, for example?
22:06	joshua__	amalloy: I've done it before, but not all the time. Only once when I made a internet capable chess game for my an end-of-semester project.
22:06	amalloy	when you do (.read sock), if there's data available, you get it immediately; if not, your process falls asleep until there is. this happens transparently to your program so you don't need to thing about it
22:07	amalloy	file IO is the same: the data usually isn't available the second you ask for it, so your process falls asleep for a millisecond or two while the disk spins up
22:07	joshua__	Oh this is making a lot more sense now.
22:07	joshua__	I was thinking in terms of a database I would read the queue from instead of a socket that I would send it through.
22:08	amalloy	so the most straightforward way (maybe not best) to implement brehaut's suggestion is to write your processing program as a server that listens to some local socket and pulls events out of it
22:08	amalloy	the "add work" program connects to that local socket and dumps in some work
22:08	brehaut	joshua__: what queue implementation are you using?
22:08	joshua__	and than the code for submitting an item to the queue would push something into that .
22:08	joshua__	brehaut, haha.. I wasn't. I was using a table in mongodb ;p
22:08	brehaut	joshua__: oh.
22:09	joshua__	brehaut, but conceptually it is a list of things to process.. ;p
22:09	brehaut	joshua__: conceptually yes, but on the other hand, there are a heap of good queue servers around
22:09	brehaut	and java APIs are pretty common
22:10	joshua__	brehaut, I agree that your guys ideas are better than my way of doing it. I think I'm going to implement amalloy's suggestion unless someone wants to toss out a better approach.
22:11	brehaut	https://github.com/robey/kestrel ?
22:11	brehaut	you'll learn stuff from doing it by hand with sockets
22:12	joshua__	I think that is the way I want to go in part for the learning and in part because kestrel sounds like overkill
22:14	joshua__	Thanks for the help guys. Best computer science education time can buy in #clojure ;)
22:16	brehaut	no worries
22:16	amalloy	programming with birds is always overkill
22:16	brehaut	haha
22:20	brehaut	$findfn [\a \b \c] true
22:20	sexpbot	[clojure.core/== clojure.core/sequential? clojure.core/reversible? clojure.core/distinct? clojure.core/boolean clojure.core/vector? clojure.core/counted? clojure.core/associative? clojure.core/< clojure.core/= clojure.core/> clojure.core/>= clojure.core/<= clojure.core/ifn? clojure.core/coll?]
22:20	brehaut	$findfn [\a \b nil] false
22:20	sexpbot	[clojure.core/keyword? clojure.core/chunked-seq? clojure.core/fn? clojure.core/not= clojure.core/nil? clojure.core/string? clojure.core/sorted? clojure.core/false? clojure.core/true? clojure.core/symbol? clojure.core/number? clojure.core/integer? clojure.core/seq? cl... http://gist.github.com/838151
22:21	brehaut	waaay to general
22:21	brehaut	i fail
22:28	TimMc	$findfn [\a \b \c] true ==
22:28	sexpbot	[]
22:28	TimMc	:-P
22:29	TimMc	brehaut: What are you looking for, anyway?
22:30	brehaut	(every? identity [a b c])
22:30	brehaut	something to test that none of the vars are nil
22:30	TimMc	or false
22:31	TimMc	,(every? (complement nil?) [\a \b "c"])
22:31	clojurebot	true
22:31	TimMc	But you want a single fn?
22:31	brehaut	TimMc: i know that they arent going to be false
22:31	TimMc	(apply and [\a \b \c])
22:32	TimMc	:-P
22:32	TimMc	I always forget I can't do that.
22:33	rabidsnail	Can I compile a clojure namespace to java bytecode and put it in, for example, a database? Or does bytecode have to go on the filesystem?
22:35	TimMc	Idiom/philosophy question! I'm developing this small library. Should I check for and throw exceptions on bad inputs, or should I expect relying code to give good inputs?
22:35	TimMc	(Relying code will only hurt itself with bad inputs.)
22:35	brehaut	you should check for bad inputs, but throwing exceptions is debatable
22:36	amalloy	brehaut: you'd rather return nil?
22:37	brehaut	amalloy: no :P but 'exceptions' is a bit debatable
22:37	amalloy	brehaut: if you're checking for bad inputs, and not returning nil or throwing an exception, what are you doing when you get a bad input?
22:37	brehaut	pass back some sort of fault type?
22:37	brehaut	gets a bit monadic though
22:38	TimMc	brehaut: They generally return nil on bad inputs anyway, just due to implementation.
22:41	brehaut	TimMc: its not too bad if the input is simple
22:42	TimMc	Maybe I'll just put validation on the main, non-recursive API calls.
22:42	TimMc	Should catch most client errors that way.
22:43	brehaut	TimMc: i think c.c has some error handling librarys that make exceptions better
22:43	TimMc	I don't care about catching them, I just want to fail fast if the client is passing in bad args.
22:43	TimMc	But that's good to know.
22:44	brehaut	wel if you dont care, then nil :P
22:44	rabidsnail	Is it still the case that not all of the core Clojure datastructures are serializable?
22:44	rabidsnail	I remember that being true in 0.9
22:45	rabidsnail	(and maybe 1.0, although I stopped using clojure around then)
22:45	TimMc	brehaut: That won
22:45	TimMc	That won't make the client fail fast.
22:45	skelternet	serializable?...as in java.io.Serializable?
22:45	rabidsnail	yeah
22:46	TimMc	I know this because my own client code was passing in a bad keyword, and I was getting nil propagation tht I only detected later.
23:27	skelternet	I could ( reduce into myListOfVectorTuples myOtherListOfVectorTuples myOtherListOfVecotrTuples) to produce my desired list of all vectors, but I can't help but think there is an easier, more idiomatic and lazy way.
23:30	amalloy	skelternet: ummmm, did you ask an actual question?
23:30	skelternet	heh...lazily? sort of?
23:30	skelternet	I think I expressed angst, rather than actually asked it.
23:31	spewn	skelternet: lazy-cat?
23:31	amalloy	spewn: afaik there is no reason to use lazy-cat after 1.1.0. concat is lazy
23:31	spewn	Good to know, thanks.
23:33	skelternet	I'll look at lazy-cat again. It was returning lists of lists and I was trying to unify into one large list.
23:34	skelternet	or seq
23:34	spewn	skelternet: Like amalloy said, look at concat instead.
23:35	amalloy	skelternet: to glue together a list of lists into one list of all the sub-elements, (1) make sure you actually want to do it, (2) (apply concat list-of-lists)
23:36	amalloy	&(apply concat [[1 2] [3 4 6] [9]])
23:36	sexpbot	⟹ (1 2 3 4 6 9)
23:36	skelternet	Thanks! I've actually had an itch to second-guess the assumption (1)
23:38	amalloy	if you're getting the list of lists from a (map ...) or (for ...), you can generally cut out the middle man by asking that process to give you a single list to begin with
23:43	skelternet	it's a list comprehension that is feeding table names to a function that returns column definitions extracted from a remote wiki page.
23:44	skelternet	I'll explore tweaking the for or the function (which I'm sure has a for in it as well)
23:46	tomoj	lazy-cat doesn't even evaluate the coll exprs until needed
23:46	tomoj	I can't think of an example, but it seems like that could be useful
23:50	brehaut	"java.lang.Exception: Unable to resolve symbol: in this context (NO_SOURCE_FILE:0)"
23:50	brehaut	anyone seen an error like that before?
23:52	skelternet	do you have a lone apostrophe next to a character that appears to be blank ?
23:52	joshua__	( )
23:54	brehaut	hmm nothing like that
23:55	joshua__	I think I get errors 'like' that when I try to call a function that doesn't exist.
23:55	joshua__	,(as)
23:55	clojurebot	java.lang.Exception: Unable to resolve symbol: as in this context
23:55	amalloy	brehaut: you were doing stuff with \tab or something, right? is it possible that you have a macro that's not quoting \space properly?
23:56	brehaut	its possible…
23:56	brehaut	binary chop ATM
23:57	amalloy	&(let [x (symbol \space)] `(var ~x))
23:57	sexpbot	java.lang.ClassCastException: java.lang.Character cannot be cast to java.lang.String
23:57	amalloy	&(let [x (symbol " ")] `(var ~x))
23:57	sexpbot	⟹ (var )
23:58	amalloy	a bit comical that (symbol " ") is even allowed, but...
23:59	brehaut	ha yeah
23:59	brehaut	i tihnk i have a hidden character
23:59	brehaut	i removed everything and it still balked
23:59	amalloy	brehaut: i've always suspected you of having character after all