#clojure – 2010-12-27

2010-12-27

00:00	qbg	And also for the fact that they queue up actions
00:00	Guest32627	qbg: i guess combined with an error handler on your agent to make sure errors get logged to, that works pretty well
00:01	Guest32627	qbg: sure, the queueing is a necessary part of the asynchronous processing. just like an MDB :)
00:01	Guest32627	well... one attached to a queue anyway, not a topic :D
00:03	qbg	Hmm... Not sure if I'll be able to add some basic syntax-class support to my syntax-rules/syntax-parse mashup tonight
00:08	qbg	Binding ns in a test feels nasty
02:17	killy971	Hello, I'm looking for some help on macros. I would like to make a factorial function with pre-calculated results (for just a few values). I got some help a while back, and have the following piece of code:
02:17	killy971	(defn static-fact [digit] (let [x 'x] `(case ~x ~@(mapcat (juxt identity fact) (range (inc digit))))))
02:17	killy971	(static-fact 10) yields the following result in the repl: (clojure.core/case x 0 1 1 1 2 2 3 6 4 24 5 120 6 720 7 5040 8 40320 9 362880 10 3628800)
02:17	killy971	What I would like then is to make a function/macro from this result.
02:18	killy971	(given that I have already defined the fact function)
02:20	tomoj	killy971: the reason is that you will be calling static-fact ofter with low values?
02:20	tomoj	s/ofter/often
02:20	sexpbot	<tomoj> killy971: the reason is that you will be calling static-fact often with low values?
02:20	killy971	yes
02:20	killy971	actually just digits
02:20	tomoj	have you considered memoize?
02:21	killy971	but I was wondering how to write some clever static code, instead of memoized or verbose long case
02:21	tomoj	oh, just to try it out?
02:21	killy971	yes, I have never really used macros until now, so I thought it could be a good occasion
02:25	killy971	I don't really understand how to stick my code in the definition of a function "digit-fact", which could be used like this: (digit-fact 3)
02:29	tomoj	I think you're right that this is a nice simple experiment
02:29	tomoj	but my brain isn't working right now
02:29	tomoj	have you ever used defmacro before?
02:30	tomoj	I mean, successfully, at all?
02:30	Scriptor	macros are fun
02:31	Scriptor	killy971: what exactly are you trying to do?
02:31	killy971	tomoj: I mean, successfully, at all?> just read stuart holloway book
02:32	killy971	Scriptor> writing a succinct factorial function with pre-computed results (for digits)
02:33	killy971	so I would like to use the macro facility to generate the part (case 1 1 2 2 3 6 4 24 ...)
02:33	killy971	I already have the following piece of code : (defn static-fact [digit] (let [x 'x] `(case ~x ~@(mapcat (juxt identity fact) (range (inc digit))))))
02:34	killy971	it yields the case part if I execute it in the repl like this (static-fact 10)
02:34	tomoj	clojurebot: hygiene?
02:34	clojurebot	Cool story bro.
02:40	tomoj	huh
02:40	tomoj	wow
02:43	killy971	any idea of how to do this?
02:43	tomoj	well
02:43	tomoj	I have a gist with a shitty answer
02:44	tomoj	https://gist.github.com/f04db48b5f33d4810de2
02:44	tomoj	sticking (range n) and (resolve f) in there seems wrong to me
02:46	killy971	I'm looking at the code
02:48	killy971	great, it works as expected. but why do you say (range n) and (resolve f) seems wrong?
02:49	tomoj	just seems odd
02:49	tomoj	also, suppose I want to caseify not with a range from 0 but with some other seq of input vals
02:49	amalloy	tomoj: resolve definitely seems like it shouldn't be necessary; i agree about range
02:49	tomoj	I tried that originally, but you'd have to eval the form they pass in or something.. ugly
02:50	amalloy	instead of n, accept a seq
02:50	killy971	oh if you mean this
02:50	killy971	ok
02:50	tomoj	amalloy: yeah.. and do what with it? it's a macro
02:50	amalloy	oh, hm
02:51	tomoj	if it's a vector, you'd want to just go with those vals. if a list, eval would get you the right answer, but..
02:51	tomoj	list or symbol, I guess..
02:55	killy971	thank you for the gist, at least it solves my prob
04:03	zvrba	hmm, how does equality work in clojure? what semantics does = have, when compared to CL? eq? eql? equal?
04:03	zvrba	ah, found it in the docs: it's value comparison.
04:04	zvrba	but given that data structures are immutable, is "value" comparison in this case implemented as identity comparison?
08:03	mrSpec	Hello! Could you tell me why (let [h my-hashmap] ...) is working, but (let [h (eval (read-from-string "my-hashmap"))]...) is not? this eval seems to work in REPL but not in the function :(
08:14	Chousuke	mrSpec: eval can't access locals. what is it that you're actually evaling?
08:14	mrSpec	it is global hashmap
08:15	mrSpec	(def hash (new java.util.LinkedHashMap))
08:15	Chousuke	also, what is the error?
08:16	mrSpec	here is the problem... I cant see the error, Jslider is just not working
08:16	Chousuke	hmh
08:16	Chousuke	your problem is probably using eval in the first place :P
08:16	mrSpec	ok I've used (if ...) instead of eval...
08:17	Chousuke	but I can't really suggest anything better since I don't know what you're trying to do.
08:17	mrSpec	ok
08:17	mrSpec	unfortunately i'm in rush. so I'll ask about this later, and tell more :)
10:43	chouser	ugh. maven fail. http://tinyurl.com/2b6azmz
11:51	drewolson	hey all. suppose i wanted to store a java.util.Random in a ref and call the .nextInt function on it inside a dosync. I'm assuming simply calling (dosync (.nextInt @rand)) will not actually be synchronous because i'm not using alter or commute. is this correct?
11:52	qbg	It will be executed
11:52	qbg	But .nextInt has side effects, so you shouldn't use it in a dosync
11:53	qbg	Why do you want to use dosync here?
11:53	drewolson	qbg: i want to ensure multiple threads can generate distinct random numbers. i may be completely off here.
11:54	qbg	Isn't .nextInt already synchronized?
11:54	drewolson	qbg: it may well be, i'm not sure.
11:54	qbg	No
11:55	qbg	Doesn't appear to be
11:55	drewolson	qbg: so i'd like to access it sychronously, but i'm not sure how to do that using alter/commute.
11:56	qbg	Sounds like (locking @rand (.nextInt @rand)) should work
11:56	drewolson	qbg: i'll look into locking, thanks for the help
11:56	qbg	But there is little reason to have a Random in a ref
11:57	qbg	Another thought: why share the one random object between multiple threads?
11:58	drewolson	qbg: i probably won't eventually, i just became curious about accessing a java instance concurrently with methods with side effects.
11:58	qbg	The STM only works on refs, not java objects
11:59	drewolson	qbg: great, thanks for the help
12:19	amalloy	drewolson: i agree with qbg that locking is probably the best choice here, but you might be interested in java.lang.ThreadLocal for other, similar things
12:32	LauJensen	,(str (java.util.UUID/randomUUID))
12:32	clojurebot	"fee8a2e9-b286-40fb-a9be-bac7c8ba3fb3"
12:32	LauJensen	drewolson: If you dont specifically need an int, the above will guarantee a unique return on each call. If you need an int, call hash on the result
12:33	LauJensen	No locks, no nothing
12:38	LauJensen	amalloy: Did you catch that? :)
12:39	amalloy	LauJensen: heh. that's an amusing use of uuids
12:39	LauJensen	amalloy: its called: creative
12:39	amalloy	ah, of course. that's what i meant. creative
12:55	drewolson	amalloy, LauJensen: thanks for your help
12:56	LauJensen	np
13:49	dnolen	qbg: yeah file + &form is enough I think. Now I'm excited :D
13:50	dnolen	syntax-rulez!
13:51	dnolen	cemerick: I did as well. But once you've internalized CL style macros. syntax-rules sounds like heaven. It's much less noisy and covers the common cases.
13:51	qbg	They only look hard :)
13:52	cemerick	dnolen: Perhaps that's it -- the last time I used scheme in earnest, it was before I had properly grokked CL-style macros.
13:55	dnolen	the thing I like about syntax-rules is that it eliminates common cases that require splicing. You can specify patterns.
13:55	qbg	Just pushed out the line number stuff
13:55	dnolen	qbg: sweet
13:56	dnolen	qbg: the moment you push a stable release to clojars, I'm going to replace my ugly logos.minikanren macros with syntax-rules :)
13:57	qbg	I also mailed my CA form today
13:59	qbg	The downside of the current error messages is that the filename and line number are part of the message, so you also have the filename and line number provided by the JVM which is separate...
13:59	qbg	I wonder if I could make that be correct instead...
14:01	qbg	Now I just need to implement guards and add a form for defining syntax classes
14:01	qbg	(and define a ton of built in syntax classes)
14:03	qbg	Is there a function that is equivalent to (first (filter ...))?
14:09	amalloy	qbg: i don't think so. there's (some), but that gets you (f x) instead of x
14:10	qbg	It seems like it could be a useful function to have (for communicating a concept)
14:11	amalloy	qbg: i agree. i've written (first (filter ..)) enough times that it ought to be abstracted out
14:12	qbg	What would it be called? some is already taken
14:26	dnolen	qbg: pick?
14:27	amalloy	qbg: (only even? (range))?
14:28	qbg	It should make sense in context of (if (<name> ...) <stuff to do if there is at least one such element>)
14:28	aqclj	hello
14:28	qbg	amalloy: only implies filter to me, not (first (filter ...))
14:29	qbg	pick might work, but I feel it is a bit lacking
14:30	qbg	find?
14:30	qbg	I think that is what it is called in CL
14:30	stuartsierra	`find` is taken
14:30	qbg	Oh, yes
14:31	qbg	It is called find-if in CL
14:31	Obvious	find-if
14:31	Obvious	yep
14:32	qbg	Maybe find-pred?
14:32	qbg	Not as nice as a single word though...
14:32	amalloy	stuartsierra: since you mention it, why does find exist? it looks like get is a perfect drop-in substitute
14:33	stuartsierra	`find` returns the actual Map.Entry, not just the value.
14:36	aqclj	Hi, I have something like: (["x" LazySeq] ["x2" LazySeq] ...). I would like to get the first n bigger values from all the LazySeq. Any ideas?
14:36	LauJensen	Any brilliant webdesigners in here, who would like to contribute either a design or a mock for clojureql.org ?
14:37	qbg	aqclj: Could you give sample input and output?
14:37	aqclj	yes
14:38	aqclj	the input would be the above sequence, and the LazySeqs are sequences of numbers
14:38	aqclj	and as output I would like to have the number of times "x" got the bigger number, and so on
14:39	aqclj	I know how to get the bigger value each time, but I don't know how to make the loop, and to select the next value in the LazySeq
14:41	qbg	I think I see what you want
14:42	stuartsierra	Use `map` to return a sequence of "x"s or "x2"s representing who had the bigger number each time. Then call `frequencies` on that result.
14:45	aqclj	thanks, I'm trying that now (I'm slow)
14:45	qbg	https://gist.github.com/756469 maybe?
14:45	qbg	(could be better)
14:47	qbg	Actually, that is going to be smallest...
14:47	qbg	Fixed
14:49	aqclj	the code got stuck, like in a infinite loop
14:49	aqclj	maybe it's because my lazyseq has no ending :S
14:50	qbg	It does it for all values, not only the first n
14:50	qbg	fixed
14:51	qbg	That code could be much better
14:53	aqclj	thanks, I'm trying to understand it now. It seems that something goes wrong, but now it doesn't get stuck
14:53	qbg	It could be that I'm misunderstanding what exactly you want
14:55	aqclj	at each loop, the bigger value within all the lazyseqs should be replaced by the next in the sequence
14:55	Berengal	Does putting anything inside a do at the toplevel make a difference?
14:56	qbg	Berengal: I don't think so
14:56	qbg	aqclj: Is this for sorting or something?
14:57	qbg	(like a merge sort)
14:57	aqclj	more or less
14:57	aqclj	for example
14:57	Berengal	qbg: Thanks
14:58	Berengal	Also, what's the prefered idiom for updating a single value in a map/struct?
14:58	qbg	assoc
14:58	amalloy	Berengal: update-in
14:58	amalloy	or assoc, depending
14:58	Berengal	amalloy: assoc makes a new entry, doesn't it?
14:58	amalloy	Berengal: overwriting any previous entry that was there
14:58	qbg	Yes, maps/structs are immutable
14:58	aqclj	if the lazyseq for "x1" is (10 8 4 2) and the lazyseq for "x2" is (33 9 2 1), and I ask for 3, I should get "x1" 1 and "x2" 2
14:59	qbg	aqclj: I would first write a function that returns a sequence of "x1"/"x2"/etc., then take n of them, and then pass that to frequencies
15:00	amalloy	so if you want to "update" the value to, say, 4, you should just (assoc m k 4); if you want to change the value based on its current value, you want (update-in m [k] function-of-value)
15:00	Berengal	qbg: That's okay. I don't want to mutate, I just want a slightly modified value, based on the previous value at an entry
15:00	Berengal	amalloy: Thanks, that looks like it
15:00	qbg	,(assoc {:a 1, :b 2} :a 5)
15:00	clojurebot	{:a 5, :b 2}
15:00	amalloy	&(update-in {:a 1, :b 2} [:a] inc)
15:00	sexpbot	⟹ {:a 2, :b 2}
15:01	aqclj	qbg: but that it wouldn't be lazy, would it? At each loop I should only ask for the next value in the lazyseq that got the max value
15:02	aqclj	or I am wrong? :S
15:02	qbg	aqclj: Define that function to use lazy-seq
15:02	qbg	And use recursion
15:03	aqclj	ok thanks, I will try that
15:05	qbg	aqclj: Updated the gist to have that function instead
15:05	qbg	(assumes the input is a map)
15:08	aqclj	thanks again, I'm trying it
16:04	DanielGlauser	/msg NickServ identify 1l2gbOGH
16:05	dakrone	DanielGlauser: time to change that password :)
16:05	DanielGlauser	Oh crap
16:05	DanielGlauser	I guess it is :)
16:05	qbg	What? I only see ********
16:05	qbg	;)
16:08	qbg	Eww, I just used eval...
16:27	ngw	what libs are available for s3 and aws in general ?
16:28	cemerick	ngw: jclouds has the deepest support for aws AFAIK (and provides clojure wrappers for much of it)
16:29	cemerick	disclaimer: I'm a contributor there
16:30	ngw	thanks
16:35	DanielGlauser	Phew, I changed my password
16:36	DanielGlauser	/msg NickServ identify abc123
16:40	qbg	lolz
16:42	qbg	Almost got guards ready for my syntax-rules/syntax-parse mashup. I just need to make sure that the code in the guards will be namespace properly
16:42	qbg	*namespaced
16:45	qbg	Hmm... Maybe binding ns around eval would be good enough
16:53	ngw	any suggestion about how to structure a project in clojure ?
16:53	ngw	I'm messing (and I mean it) with leinigen but coming from ruby/python it's kind of confusing
16:54	amalloy	ngw: cake is similar to leiningen but uses a little ruby underneath; not sure if that's helpful
16:54	ngw	for example I just discovered there's a -main function, something that none of the books I've read about clojure mentions it
16:55	amalloy	ngw: -main isn't special, per se. -foo is how to create a MyClass.foo() method when AOT compiling
16:56	pdk	yknow i should get around to installing cake or lein
16:56	pdk	though how is the installation process on windows
16:56	amalloy	but both of them have a project.clj file in the project root to do configuration and management, and you can find a reasonable reference to that file format at http://is.gd/jAFJV
16:58	aqclj	I have a sequence of maps called m, when use (into {} m) it only returns one of the maps. How could I get all the maps outside the sequence so I can use the merge-with function?
16:59	amalloy	&(apply into {} [{:a 1} {:b 2, :c 3}])
16:59	sexpbot	java.lang.IllegalArgumentException: Wrong number of args (3) passed to: core$into
17:00	amalloy	&(apply merge-with + [{:a 1} {:b 2, :a 3}])
17:00	sexpbot	⟹ {:b 2, :a 4}
17:00	amalloy	aqclj: ^^
17:01	aqclj	amalloy: thanks a lot!
17:01	aqclj	what the & do?
17:01	amalloy	aqclj: asks sexpbot to evaluate for me
17:02	aqclj	ah ok
17:02	Luyt_	is it possible to have clojurebot do a deathmatch with sexpbot?
17:05	Luyt_	&(println ",(doc doc)")
17:05	sexpbot	⟹ ,(doc doc) nil
17:05	qbg	,(println "&(println \"Foo\")")
17:05	clojurebot	&(println "Foo")
17:05	sexpbot	⟹ Foo nil
17:06	qbg	Now to quine it...
17:06	Luyt_	qbg - Luyt: 1-0 !
17:06	Luyt_	I tried to fool sexpbot into luring clojurebot out, that failed, you tried it the other way, that worked.
17:07	qbg	Yeah, sexpbot is going to make this hard...
17:07	Luyt_	sexpbot's output always starts with ⟹ and as such can never get an answer out of clojurebot.
17:07	qbg	&(println "\n,(doc doc)")
17:07	sexpbot	⟹ ,(doc doc) nil
17:07	Raynes	I've done my part. Any exploitation will be on clojurebot. Thus, I void all responsibility. ;)
17:07	amalloy	Luyt_: sexpbot was carefully designed to prevent this :P
17:07	Luyt_	Good thing ;-)
17:08	qbg	&@(future (println ",(doc doc)"))
17:08	sexpbot	⟹ nil
17:08	Luyt_	Now, what if clojurebot responded to ",(...)" and sexpbot to ",,(...)" (note two comma's instead of one)
17:08	Raynes	amalloy: Haha "carefully designed". More like horribly designed until _ato broke it in every which way imaginable and forced me to fix it... carefully. :>
17:09	amalloy	Raynes: carefully designed /eventually/
17:09	Raynes	That
17:09	qbg	&(let [i in] @(future (binding [in i] (println ",(doc doc)"))))
17:09	sexpbot	⟹ nil
17:09	Raynes	is better.
17:09	qbg	&(let [i out] @(future (binding [out i] (println ",(doc doc)"))))
17:09	sexpbot	⟹ ,(doc doc) nil
17:09	Raynes	qbg: You can also experiment with sexpbot in PM or in #sexpbot
17:09	Raynes	In case it gets too floody for #clojure.
17:11	Luyt_	First versions of my programs always look a bit clumsy. Only after reshaping them they become a bit elegant. Like a clump of clay you have to sculpt and refine.
17:11	qbg	sexpbot wins this round...
17:12	qbg	Lets not quine clojurebot...
17:21	jlaskowski	hi
17:21	jlaskowski	I'm having troubles with java.lang.IllegalArgumentException: No matching method found: createInjector
17:22	jlaskowski	CLASSPATH=`pwd`/guice/guice-3.0-rc1.jar:`pwd`/guice/javax.inject.jar:`pwd`/guice/aopalliance.jar clj -13
17:22	jlaskowski	CLOJURE_DIR: /Users/jacek/apps/clojure
17:22	jlaskowski	CLOJURE_CONTRIB_JAR: /Users/jacek/apps/clojure-contrib-1.3.0-alpha3.jar
17:22	jlaskowski	Clojure 1.3.0-alpha4
17:22	jlaskowski	(def mm (proxy [AbstractModule] [] (configure [] (println "configure called"))))
17:22	jlaskowski	(bean mm)
17:22	jlaskowski	{:class user.proxy$com.google.inject.AbstractModule$0}
17:22	jlaskowski	and when I call (Guice/createInjector mm)
17:22	jlaskowski	it spits out the exception
17:23	jlaskowski	http://google-guice.googlecode.com/svn/trunk/javadoc/com/google/inject/AbstractModule.html
17:23	jlaskowski	how can I find out what is wrong exactly?
17:24	jlaskowski	how do I find out what Clojure can call upon a class?
17:24	jlaskowski	any helpful reflection methods to use?
17:25	amalloy	jlaskowski: createInjector takes an array of Modules, not a single module
17:25	amalloy	java's Foo.bar(Whatever...) is sugar for arrays
17:25	jlaskowski	right
17:26	jlaskowski	but have a look at the full stack trace
17:26	jlaskowski	user=> (.printStackTrace *e)
17:26	jlaskowski	java.lang.IllegalArgumentException: No matching method found: createInjector
17:26	jlaskowski	at clojure.lang.Reflector.invokeMatchingMethod(Reflector.java:77)
17:26	jlaskowski	at clojure.lang.Reflector.invokeStaticMethod(Reflector.java:202)
17:26	jlaskowski	at user$eval17.invoke(NO_SOURCE_FILE:4)
17:26	jlaskowski	at clojure.lang.Compiler.eval(Compiler.java:6201)
17:26	jlaskowski	at clojure.lang.Compiler.eval(Compiler.java:6168)
17:26	jlaskowski	at clojure.core$eval.invoke(core.clj:2680)
17:26	jlaskowski	at clojure.main$repl$read_eval_print__5619.invoke(main.clj:179)
17:26	jlaskowski	at clojure.main$repl$fn__5624.invoke(main.clj:200)
17:26	jlaskowski	at clojure.main$repl.doInvoke(main.clj:200)
17:26	jlaskowski	at clojure.lang.RestFn.invoke(RestFn.java:422)
17:26	jlaskowski	at clojure.main$repl_opt.invoke(main.clj:266)
17:26	jlaskowski	at clojure.main$main.doInvoke(main.clj:361)
17:26	amalloy	augh do not do that
17:26	amalloy	http://gist.github.com
17:26	jlaskowski	amalloy: ok, will use it
17:27	amalloy	anyway, yes. it can't find a method with that name whose parameters are (Foo), only one whose parameters are (Foo[])
17:28	jlaskowski	you're right!
17:28	lancepantz	does anyone have any experience with the :exposes-methods option to genclass? I'm trying to hook into the servlet init method: https://gist.github.com/756639
17:28	jlaskowski	so how can I call a method that accepts an array?
17:28	amalloy	you can find this out for yourself with clojure.contrib.repl-utils/show
17:28	amalloy	jlaskowski: ##(doc into-array) is one way; in this case it looks like Guice will also accept an Iterable, so you can just pass it a clojure vector
17:28	sexpbot	⟹ "([aseq] [type aseq]); Returns an array with components set to the values in aseq. The array's component type is type if provided, or the type of the first value in aseq if present, or Object. All values in aseq must be compatible with the component type. Class objec... http://gist.github.com/756642
17:28	Luyt_	The topic could say 'Don't paste into the channel, use a pastebin like http://paste.pocoo.org/'
17:29	jlaskowski	Luyt_: nice of you :)
17:29	Luyt_	well, #python has it, and many other channels too.
17:30	jlaskowski	HURRAYY - you saved my day, amalloy
17:30	jlaskowski	it works fine now
17:30	Luyt_	Freenode's channels are a great resource, because of all the friendly and knowledgeable people on it!
17:30	jlaskowski	it's awesome how quickly it's sorted out!
17:31	Luyt_	...and some communities are really great.
17:31	lancepantz	we just have a great community :)
17:31	jlaskowski	it's not the first time I just enter the channel
17:31	jlaskowski	and get an answer in secs
17:31	jlaskowski	unbelievable
17:32	jlaskowski	thanks again
17:32	Luyt_	as long as you don't become a Help Vampire (http://slash7.com/2006/12/22/vampires/) it's allright ;-)
17:33	Luyt_	and you can always give back to the community, of course. Like lurking and answering questions from noobs, which are too tedious for the advanced clojurists in here. (Same works in #python)
17:36	amalloy	Luyt_: thanks for the Help Vampire link. it's cute
17:39	Luyt_	amalloy: Cute, yes, but there's also a very warning in there...
17:39	Luyt_	very real*
17:39	amalloy	Luyt_: yes, i'm familiar with the problem
17:40	Luyt_	Now, luckily I haven't seen it happening here yet, since clojure is quite esoteric and only intelligent (?) people are attracted to it, but it happened at #php if I remember correctly.
17:41	Luyt_	...and also on the python mailing list, at least a few housework-assignment like questions (formulated as demands) come passing by every week.
17:46	TakeV	If I define an atom in one namespace, and have functions that manipulate it in the same namespace, then why is the atom not changing when I call those functions in another namespace?
17:47	pdk	what would be an equivalent to letfn that supports mutual recursion
17:48	dnolen	pdk: you can use trampoline /w your letfns
17:48	pdk	whew boy
17:48	pdk	(doc trampoline)
17:48	clojurebot	"([f] [f & args]); trampoline can be used to convert algorithms requiring mutual recursion without stack consumption. Calls f with supplied args, if any. If f returns a fn, calls that fn with no arguments, and continues to repeat, until the return value is not a fn, then returns that non-fn value. Note that if you want to return a fn as a final value, you must wrap it in some data structure and unpack it after trampoline r
17:49	amalloy	TakeV: it should work. maybe post a simple gist that demonstrates your problem?
17:49	qbg	The bindings in letfn are recursive, so there should be no problem
17:50	TakeV	amalloy: A what?
17:50	amalloy	TakeV: http://gist.github.com
17:53	TakeV	Ah, nevermind. It seems that I was calling the wrong atom. Oops.
17:53	rata_	hi
18:04	qbg	I love the foo example that I just added to the readme at https://github.com/qbg/syntax-rules
18:08	rata_	qbg: nice work =)
18:09	dnolen	qbg: when you got time. you should make a simple github tutorial page comparing common use of CL style macros w/ steps to convert to syntax-rules. The Ring tutorial are a great example IMO, http://mmcgrana.github.com/2010/03/clojure-web-development-ring.html
18:09	qbg	I just need to write some code to define syntax classes, and define a bunch of them now
18:10	qbg	(and add syntax-case support also, but that should be rather trivial)
18:10	qbg	The power of this library is far beyond syntax-rules at this point
18:11	qbg	I need to come up with a better name (and one that isn't too cheesy)
18:28	benreesman	hi quick question: is there some literature that explains the clojure philosophy around when to use types/records/protocols and the multimethod/hierarchy system? what's the idiomatic way of creating types that e.g. know how to print themselves?
18:29	qbg	From what I've seen, you provide an implementation of the print-method multimethod
18:29	qbg	(or whatever it is called)
18:29	qbg	In addition to toString
18:30	benreesman	specified on the name of the defrecord?
18:30	qbg	You shouldn't need to do any of that for defrecord, only deftype
18:30	qbg	If you think you do, you are probably doing it wrong
18:31	qbg	What are you trying to implement?
18:32	benreesman	i need a servlet that takes a streaming http endpoint and splits it into multiple streams. i'm just trying to get my head around the new clojure abstractions as i haven't used the language in over a year
18:32	qbg	You use records as a typed map for the protocol system, and types for implementing data structures
18:33	benreesman	types/protocols and multimethods seem to have some overlap in their purpose
18:33	benreesman	to the untrained eye, that is
18:33	benreesman	i think i understand the difference between a type and a record
18:33	qbg	Use multimethods if you need hierarchies or multiple dispatch
18:34	qbg	Use the protocol system if you need polymorphism on groups of functions
18:34	qbg	Use functions if you don't need any of that
18:34	benreesman	is it idiomatic to use multiple dispatch with types/records?
18:34	qbg	types/records only provide single dispatch
18:35	benreesman	so if i want multiple dispatch i should continue to use defstruct?
18:35	qbg	*well, the protocol system
18:35	benreesman	really appreciate your time by the way
18:36	qbg	If you don't need to use the protocol system, you could use just maps instead
18:37	rata_	qbg: what about records vs maps performance?
18:38	qbg	records have potential performance advantages
18:38	dnolen	benreesman: multimethods are more general. I've come to the conclusion they are most useful for the "scripting" layer of an application, where you need the most generality and/or where performance is mostly a wash (triggering IO related things).
18:38	dnolen	when you know you're interested in performance (some essential data structure) reach for protocols deftype/record
18:39	benreesman	right, i'm not bothered about performance at the moment, i just want to use the most idiomatic type and dispatch abstraction. i like multiple dispatch better in general but was always bothered by the lack of a canonical type field for the types. i was wondering if defrecord solved that.
18:40	qbg	defrecord/deftypes creates classes, so they have a type
18:42	benreesman	maybe what i need to do is read some code? any pointers to a non-trivial open source project written in a modern and idiomatic clojure style?
18:43	dnolen	qbg: about syntax-rules. +& is a bit weird, considering what it does - it's a grouping operator. also +sym's are kinda ugly. why not just use keywords? and let the user specify which keywords they want to allow as part of the macro.
18:43	qbg	For full-blown stuff, there is the gvec stuff in core
18:43	benreesman	wonderful i'll have a look
18:43	qbg	dnolan: +& is technically redundant at this point (+head and ...)
18:44	benreesman	much obliged
18:46	dnolen	qbg: sure, mostly critique about +sym convention. why not keywords?
18:48	joshua__	How do I save a file using duck streams to a folder other than the working directory?
18:51	amalloy	did someone improve clojure-mode's eldoc or something recently? i've just noticed that when point is over a var, the minibuffer echoes the current value of that var
18:53	mrBliss	The slides in the recently released Conj video about zippers are ahead of the speaker vid by 20s, which makes it very hard to follow, certainly when he's working in the REPL. (Too bad XBMC only allows an audio offset of maximum 10s). How come the uploaders didn't notice this?
18:56	lazy1	joshua__: Something like https://gist.github.com/756712 ?
19:05	qbg	Sorry, got disconnected
19:05	qbg	dnolan: I used +syms because they are commonly used in source code
19:05	qbg	And so they are unambiguous
19:06	qbg	Also, because syntax-parse has ~syms for additional directives
19:07	joshua__	lazy1: thanks.
19:08	joshua__	lazy1: I got confused because I tried \\temp\\blah instead /temp/blah
19:08	joshua__	lazyl: and that faile
19:12	lazy1	joshua__: To be OS agnostic, you probably want to join part on File/separator
19:14	lazy1	Though Java might do the / to \ conversion for you, I don't know
19:17	amalloy	lazy1, joshua__: i think it does the conversion sometimes, as if that were helpful
19:19	Guest10433	http://pastebin.com/z5P2n9vM is one of these preferable to the other in clojure?
19:20	lancepantz	Guest10433: i like a better
19:21	Guest10433	lancepantz: thanks. i was just wondering if one way was considered better style
19:21	amalloy	Guest10433: a for sure. the (thingN)s should all line up; i prefer a, but if you indented lines 9 and 10 to match line 8 i think that would be acceptable
19:22	Guest10433	thanks amalloy.
19:24	joshua__	Hmm. How do I create a folder that doesn't exist?
19:25	lazy1	joshua__: Most of FS functionality is in java.io.File (see http://download.oracle.com/javase/6/docs/api/java/io/File.html)
19:25	amalloy	$google java io file create
19:25	sexpbot	First out of 127000 results is: Creating a File \| Example Depot
19:25	sexpbot	http://www.exampledepot.com/egs/java.io/createfile.html
19:26	amalloy	hm. not what i was hoping google would turn up, but quite useful anyway
19:28	joshua__	duck-streams in contrib turns out to have a make-parents command. I just need to create a file that has a path there.
19:31	joshua__	So something like (duck/make-parents (java.io.File. "path/to/file.txt")) would work =)
19:31	joshua__	amalloy, thanks that led me in the right direction.
19:35	joshua__	Yep worked like a charm. Thank you everyone!
19:42	joshua__	How would I got about declaring a dependency to one of my own projects with lein?
19:43	joshua__	Like :dependency [[my-other-lein-project "1.0.0-SNAPSHOT"]]
19:43	tomoj	look in your project's project.clj to determine
19:43	amalloy	joshua__: i'm not sure about lein, but in cake you can $ cake install in my-other-lein-project to deploy it to your local repo
19:44	lazy1	lein has install as well
19:44	ninjudd	amalloy: 'lein install' works too
19:44	tomoj	if you are hacking on both projects at once, symlink checkouts/my-other-project to the root of my-other-project
19:44	joshua__	lein install sounds like the right route than =)
19:44	tomoj	and also include the dep
19:45	tomoj	then when your symlink is in place, the code there will take precedence over a jar in your local repo
19:46	joshua__	This seems to have been surprisingly easy.
19:46	joshua__	lein install.. 2 seconds later.. lein deps in other project
19:46	joshua__	no errors ?
19:46	joshua__	=) very nice
20:27	bendlas	hey
20:28	bendlas	Can somebody tell me what's going on here
20:28	bendlas	,(deftype Vec2 [^double x
20:28	bendlas	^double y]
20:28	bendlas	Object
20:28	bendlas	(equals [this other]
20:28	clojurebot	EOF while reading
20:29	bendlas	(println :other-type (type other) \newline
20:29	bendlas	:this-type Vec2 \newline
20:29	bendlas	:instance? (instance? Vec2 other)\newline
20:29	bendlas	:=type? (= (type other) Vec2))
20:29	bendlas	(and (instance? Vec2 other)
20:29	technomancy	bendlas: step one: pastebin
20:29	bendlas	(== (.x this) (.x other))
20:29	bendlas	(== (.y this) (.y other)))))
20:29	bendlas	right
20:31	bendlas	http://pastebin.com/AgNVKFhW
20:31	bendlas	anyway, when i do (= (Vec2. 5 6) (Vec2. 5 6))
20:32	bendlas	(instance? Vec2 other) in the overridden equals gives false
20:32	bendlas	while (= (type other) Vec2) gives true
20:32	bendlas	wtf?
21:13	qbg	Finally done with implementation of syntax class definition for https://github.com/qbg/syntax-rules
21:13	qbg	Now to document and do a commit
21:18	joshua__	Is there a simple way to pass a string to enlive as an html resource?
21:19	joshua__	Instead of a file/url that is.
21:23	joshua__	I guess I'll just wip out a regular expression.. seems like it will be faster
21:26	bendlas	joshua__: html-snippet, I think
21:28	joshua__	Didn't work ;p
21:28	joshua__	ouch
21:30	joshua__	Apparently that is how its suppose to be done though.
21:31	joshua__	I think it was just my string being malformed.
21:31	joshua__	Thanks bendlas!
21:33	bendlas	np
21:41	joshua__	$findfn ["\n\ntest"] "test"
21:41	sexpbot	[]
21:41	joshua__	$findfn "\n\ntest" "test"
21:41	sexpbot	[clojure.string/trim clojure.string/triml clojure.contrib.string/trim clojure.contrib.string/ltrim]
21:41	joshua__	omg omg
21:41	joshua__	The function.. it works =)
21:48	tomoj	technomancy: thanks! I went to check sample.project.clj for the syntax for exclusions, and found exactly the log4q exclusions I needed :D
21:48	tomoj	er, log4j
22:00	dnolen	so for contrib 1.3.0 how do I include a contrib library in a project.clj?
22:10	qbg	Finally, syntax class definitions
22:10	qbg	And an improved plet example
22:11	qbg	Awesome error messages FTW
22:13	qbg	Needs syntax sugar for pattern variables with a parameterless syntax classes though
22:13	qbg	*class
22:30	Berengal	Is it possible to connect a repl to a running clojure process somehow?
22:34	tomoj	there is at least one way
22:34	Berengal	How?
22:34	clojurebot	with style and grace
22:34	tomoj	emacs user? if not, there may be a way, but I don't know it
22:34	Berengal	Yeah, I'm an emacs user
22:34	tomoj	do you use leiningen?
22:35	Berengal	Both that and maven
22:36	tomoj	you know about `lein swank` and `mvn clojure:swank` (or whatever the maven goal is..)
22:36	Berengal	But maven is probably more relevant to the projects I want to do this with
22:36	Berengal	Yeah, I do
22:36	tomoj	there is a bit of clojure code you can use to kick off the swank server from your clojure code
22:36	Berengal	Ah, nifty
22:37	tomoj	(swank.swank/start-repl)
22:37	tomoj	can pass port and host I think
22:38	tomoj	[port & opts]
22:40	Berengal	That way I can start poking around my objects and whatnot while it's live. Why doesn't every language let you do that?
22:45	wooby	Berengal, https://github.com/relevance/mycroft is a web-based jvm explorer that may also interest you
22:47	Berengal	wooby: So that's kind of a browser-based repl, right?
22:48	wooby	of sorts
22:48	Berengal	Neat
22:49	technomancy	Berengal: the only reason I can imagine other languages lack a repl is that their designers have never used a language with one... but I know that's not true.
22:50	Berengal	technomancy: It's not the lack of a repl as much as the lack of a disecting a running program I'm lamenting
23:03	amalloy	technomancy: it's kinda hard to imagine what a java repl would look like, with everything having to live in classes and methods
23:04	gregh	public static void main>
23:04	amalloy	gregh: and imports? or using the repl to write more than one function?
23:05	gregh	yeah, it's not really practical. But it could be useful in a limited sense
23:05	qbg	My mashup is now a syntax-rules/syntax-case/syntax-parse mashup.
23:07	gregh	related: http://stackoverflow.com/questions/2636044/java-repl-shell
23:07	gregh	wide variety of alternatives here: http://stackoverflow.com/questions/397488/is-there-something-like-pythons-interactive-repl-mode-but-for-java
23:43	hippiehunter	when consuming java types am i supposed to access public fields using (.someField instance set-value) ?
23:43	hippiehunter	or is that just for methods
23:43	Gigaroby	i think there was somethink like (set!
23:44	Gigaroby	(set! (. instance-expr instanceFieldName-symbol) expr)
23:44	Gigaroby	all here : http://clojure.org/java_interop
23:46	hippiehunter	thanks
23:48	wooby	i knew lots of people who pre-clojure used groovy or beanshell for a repl
23:50	hippiehunter	is there a way to make set! play nice with doto?
23:54	amalloy	hippiehunter: i don't use set! for interop; can you show me what a set! form for that looks like?
23:54	hippiehunter	(set! (. instance field) value)
23:55	hippiehunter	is there something i can use instead of set!?
23:55	hippiehunter	or are you just lucky enough not to deal with public fields
23:55	amalloy	the latter, i'm afraid
23:56	Gigaroby	guys I need somethink to remove a element from a seq in a determinate position
23:56	Gigaroby	example : (remove 2 '(1 2 3 4))
23:56	Gigaroby	=>(1 2 4)
23:58	amalloy	hippiehunter: (doto instance (-> (. field) (set! 10))) maybe?
23:58	joshua__	$findfn 2 [1 2 3 4] [1 2 4]
23:58	amalloy	,(macroexpand '(doto instance (-> (. field) (set! 10))))
23:58	sexpbot	[]
23:58	clojurebot	(let* [G__870 instance] (-> G__870 (. field) (set! 10)) G__870)
23:58	joshua__	$findfn 2 [1 2 3 4] `(1 2 4)
23:58	sexpbot	[]
23:58	joshua__	$findfn [1 2 3 4] 2 `(1 2 4)
23:58	sexpbot	[]
23:59	amalloy	joshua__, Gigaroby: no single function does it; you have to chain one or two together
23:59	hippiehunter	-> is one of those things Ive not gotten around to understanding, might you point me in the direction of a noob friendly explaination