#clojure – 2010-11-20

2010-11-20

09:58	defn	let the +b's commence
10:03	krumholt	hi is there a way to create the primitive datatype byte in clojure? when i do (byte 1) i get a Byte not a byte
10:04	Chousuke	krumholt: it's a byte, but when you pass it to a function it gets boxed
10:04	krumholt	can i prevent that?
10:05	krumholt	im reading image data and its really slow. i think boxing every byte is the problem
10:06	Chousuke	you need a primitive array or a vector I suppose
10:06	Chousuke	no way to do primitive function args in 1.2
10:07	krumholt	but i could use a native array?
10:07	Chousuke	remember to remove reflection first though.
10:07	Chousuke	that's usually the biggest slowdown
10:07	tonyl	what about (.byte
10:07	tonyl	what about (.byteValue (byte 1))
10:08	Chousuke	tonyl: that's even slower :P
10:08	Chousuke	it gets boxed just to call the method on the Byte, and then it returns the byte
10:08	krumholt	Chousuke, uh thanks. i added #^java.lang.Byte and the speed increased by 1000%
10:08	tonyl	yeah true mmm...
10:08	Chousuke	krumholt: hehe
10:09	krumholt	it went from 14 seconds to 1,8 seconds
10:09	Bahman	Hi all!
10:23	Chousuke	krumholt: It's good to bind warn-on-reflection to true when developing :)
10:23	krumholt	Chousuke, i will do that thanks
10:24	Chousuke	in the repl you can actually use set! to set it to true, so you don't need binding
10:27	krumholt	Chousuke, thanks for answering my next question before i could ask it :)
10:28	cmiles74	Does anyone have a Clojure language handler for Google Code Prettify?
11:03	Lajla	raek, but if it works, then surely it must be just a reader thing, right?
11:03	Lajla	And that means that rich LIES on his page.
11:03	Lajla	Rich' Shadow deserves no worship then
11:08	Chousuke	wtf are you talking about? :P
11:10	LauJensen	Lajla: You should really try out scala and #scala - report back here in 18 months :)
11:12	Lajla	Chousuke, what constitutes a symbol on clojure.
11:12	Lajla	The point is that the main page says that symbols can't contain spaces et cetera or . or what-not.
11:12	Lajla	Buuut
11:12	Lajla	My claim is that that is just reader praecidence.
11:13	Lajla	Like (symbol "I worship his shadow") works.
11:13	Lajla	And (symbol? that) answers true.
11:13	Lajla	Also,
11:13	Lajla	you can even use eval on that
11:14	Lajla	Like (let [funnysymb (symbol "I worship his shadow")] (eval (list (symbol "defn") funnysymb [(symbol "x")] (symbol "x"))))
11:14	Lajla	And then you can actually use (eval (list (symbol "I worship his shadow") 3)))
11:16	Chousuke	Lajla: that's because there is no validation of symbols
11:16	Chousuke	the symbols are illegal still
11:17	Chousuke	as in, you're not supposed to use them
11:17	Chousuke	because then things might break
11:35	Lajla	Chousuke, what things?
11:35	Lajla	If some things might break then, some one should mail rich to tell him that his type safety sucks an instead he should learn finnish to talk with me and Chousuke about deer and shadows to worship
11:37	Chousuke	Lajla: it's not a type safety problem
11:37	Chousuke	Lajla: it's just there being no check against the user creating stupid symbols
11:39	Lajla	Chousuke, I'd say that's a type safety problem. symbol claims to output symbols from strings, if you give it input from which it cannot produce a symbol, it should produce a runtime error.
11:39	Lajla	Instead of just going on with it and producing something which is apparently 'garbage'
11:39	Chousuke	Lajla: well, duh
11:39	Lajla	Which strangely eval also accepts.
11:39	Lajla	A bit sloppy, some would say.
11:39	Lajla	But I think
11:39	Chousuke	Lajla: the thing is, no-one has yet come up with a patch to implement such validation
11:40	tonyl	Lajla: are you joking around or is this for real?
11:40	Lajla	the best wat is to just let symbols contain any and all characters strings can contain.
11:40	Chousuke	and since it's not a big issue, there's no rush to implement one
11:40	Lajla	And just have no reader syntax for it.
11:40	Lajla	tonyl, I am f0 real.
11:40	tonyl	ok
11:40	Lajla	I am very theoretical.
11:40	Lajla	I like to know the finer things about programming langauges before I write a Hello World.
11:40	Lajla	Like these things
11:40	tonyl	hehe that is interesting
11:41	Lajla	I am very interesting.
11:41	Lajla	Nahh, I actually tried out in C if "string"+1 did what I expected it to do before I wrote a hello world.
11:41	Chousuke	Lajla: Allowing arbitrary characters has also been considered.
11:41	Lajla	Chousuke, what were the arguments against?
11:41	Chousuke	Lajla: but since it has so far been a non-issue, it's not implemented
11:41	Lajla	I think in most lisps they say that arbitrary chars can make symbols, but there is just no reader synta for it.
11:42	Chousuke	no arguments, just that no-one has had a need for the feature.
11:42	Lajla	Chousuke, well, it seems to work so far, do you have a place where it might screw you up?
11:42	Chousuke	Lajla: the "screw up" is that symbols with whitespace in them are not readable
11:42	Lajla	Ahh
11:42	Lajla	you mean writing and then reading?
11:43	Chousuke	ie, you can't do (read-str (pr-str weird-symbol))
11:43	Lajla	&(write (symbol "I worship your shadow"))
11:43	sexpbot	java.lang.Exception: Unable to resolve symbol: write in this context
11:43	Chousuke	and get weird-symbol
11:43	Lajla	Yeah.
11:43	Chousuke	,(print (symbol "foo bar"))
11:43	clojurebot	foo bar
11:43	Lajla	Ahhh, print.
11:43	Chousuke	see the problem? :)
11:43	Lajla	Clojure makes no difference between write and print, like cl does?
11:43	Chousuke	I'm not sure what the difference is in CL
11:43	Lajla	Well, does clojure make the claim that reading back always gives the same as what you print?
11:44	Chousuke	no
11:44	Chousuke	there's pr
11:44	Chousuke	,(pr "foo")
11:44	clojurebot	"foo"
11:44	Chousuke	,(print "foo")
11:44	clojurebot	foo
11:44	Lajla	Well, basically write gives out the 'external repraesentation' and print accepts only strings and chars I think.
11:44	Lajla	Ahh
11:44	Lajla	then pr is write
11:44	Lajla	But like
11:44	Lajla	&(pr (fn [I-worship-your-shadow] (+ 3 I-worship-your-shadow)))
11:44	sexpbot	⟹ #<sandbox6621$eval8180$fn__8181 sandbox6621$eval8180$fn__8181@110710>nil
11:45	Lajla	If I read that back in
11:45	Lajla	do I ge the same function back?
11:45	Lajla	Does it guarantee that in each case, you get the same thing back?
11:45	Chousuke	no
11:46	Chousuke	some things are not readable.
11:46	Chousuke	(#<foo>)
11:46	Chousuke	#< throws an error if you try to read it
11:46	Lajla	But does it guarantee it for symbols?
11:46	Chousuke	for legal symbols yes
11:47	Lajla	Hmm
11:48	Lajla	And does the symbol function guarantee that ...
11:48	Lajla	who am I kidding man
11:48	Lajla	I'm talkinga bout a language which has no formal specs.
11:48	Lajla	But a 'reference implemtnation'
11:48	Lajla	There are no guarantees, carry on, carry on, every bug is a feature.
11:48	Chousuke	You need to be less theoretical :P
11:50	Lajla	That comes as no surprise from someone who believes in conceptual programming. =)
11:50	Lajla	But hey, your Finnish is very good.
11:51	Lajla	I just like to know these things before I start, I don't like to hack and slash around before I know exactly what mechanically is supposed to happen with my code.
11:51	Lajla	And since Cloj has no specs, I'm just reverse-engineering it by using the bot.
11:51	Chousuke	My Finnish is good because I am Finnish :P
11:51	Chousuke	though on second thought, that is no guarantee
11:55	trybeingarun	hey guys
11:56	trybeingarun	Do monads and continuations have any practical value or are they simply theory stuff?
11:56	trybeingarun	I am having a headache trying to understand them.
11:59	trybeingarun	anybody there?
11:59	Chousuke	sure they have applications
11:59	Chousuke	you can think of monads as an API
12:00	Chousuke	for composition
12:00	Chousuke	of operations
12:00	Lajla	Chousuke, do you have good finnish for a fin though?
12:00	Lajla	High literary standard?
12:00	Chousuke	yes
12:00	Lajla	Hmm
12:00	Lajla	clojure has monads and continuations?
12:00	Lajla	How can continuations work if there is no TCO?
12:01	trybeingarun	Why do i need an API for compositions when i can write small wrapper code and use them for compositions
12:01	Lajla	Wouldn't that keep on infinitizing the stack frame.?
12:02	trybeingarun	Dudes, before u guys go into depths of these can anybody point me to any useful tutorial (beginner friendly) which won't punch a hole though my brain??
12:03	raek	trybeingarun: this is a Clojure + monads tutorial I know of: http://onclojure.com/2009/03/05/a-monad-tutorial-for-clojure-programmers-part-1/
12:04	raek	I have never used monads in clojure so far myself, though
12:04	trybeingarun	hm
12:04	raek	oh wait... you wern't looking for a tutorial... sorry
12:05	trybeingarun	thanks raek. I will see how much I understand those concepts
12:05	trybeingarun	no. in fact I was looking for a tutorial
12:05	raek	as for continuations, clojure does not have a call/cc
12:06	raek	but the ring web framework uses a control technique that I think is a bit similar to CPS
12:06	trybeingarun	okay.
12:09	raek	a handler is a function that takes a request map and returns a response map. a middleware fn takes a handler function and returns a new function
12:09	raek	the reurned function will most often proxy the request to the given handler, but might also do something else (like render an error message)
12:10	raek	(defn some-middleware [handler] (fn [request] (if (valid-request request) (handler request) (render-some-error))))
12:10	trybeingarun	okay
12:10	notsonerdysunny	the swank-clojure I am using, which is 1.3.0-snapshot, to try out the 1.3.0-alpha3 seems to be having problems .. Is anybody else facing similar problems?
12:19	_ulises	afternoon gents
12:27	Lajla	raek, but how does that work without TCO?
12:27	Lajla	I mean, obviousy loop/recur is a limit example of continuations, all languages have them, but when people say 'continuations', they generally mean 'fully general continuations'
12:27	Lajla	limited
12:35	raek	Lajla: you can only have limited levels of nesting, due to the lack of TCO
12:36	Lajla	raek, but continuations are abstracted as ordinary functions, right?
12:36	Lajla	CPS would fill the stack pretty fast.
12:37	Lajla	I am a theorete and feel no shame!
12:40	raek	yes
12:43	Lajla	&(+ 1 "string")
12:43	sexpbot	java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Number
12:43	Lajla	Hmm
12:43	Lajla	no "tring" like in C
12:43	Lajla	&(+ "string" "string")
12:43	sexpbot	java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Number
12:43	Lajla	hmm
12:43	Lajla	&(+ \a \b)
12:43	sexpbot	java.lang.ClassCastException: java.lang.Character cannot be cast to java.lang.Number
13:21	Lajla	Chousuke, can you cite me the part where it makes that reader / pr guarantee for legal symbols?
13:31	Lajla	Chousuke, totele minua, sinä orjani.
13:32	mattmitchell	is there a library that will take a url/string and parse it out into fields like, host, path, query etc.?
13:33	technomancy	,(bean (java.net.URL. "http://technomancy.us:80"))
13:33	clojurebot	java.lang.reflect.InvocationTargetException
13:33	technomancy	ಠ_ಠ
13:33	Raynes	(bean (java.net.URL. "http://technomancy.us:80"))
13:33	Raynes	&(bean (java.net.URL. "http://technomancy.us:80"))
13:33	sexpbot	⟹ {:path "", :protocol "http", :authority "technomancy.us:80", :host "technomancy.us", :ref nil, :content #<HttpInputStream sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@9d4b24>, :class java.net.URL, :defaultPort 80, :port 80, :query nil, :file "", :userInfo nil}
13:33	technomancy	aha
13:34	Raynes	That's pretty cool.
13:34	Derander	I wish map but for hash-map values was in core
13:35	mattmitchell	wow awesome thanks!
13:35	technomancy	clojurebot: clearly you need to lighten up a bit.
13:35	clojurebot	1
13:36	rata_	hi
13:36	rata_	which fns can give me a PersistentList when I give it a LazySeq?
13:37	Chousuke	Lajla: there is no such guarantee.
13:37	Chousuke	Lajla: except that if you don't use illegal symbols, you won't get any illegal symbols from pr/read either.
13:37	Chousuke	Lajla: the only way you can create an illegal symbol is manually by calling "symbol", so it's a non-issue
13:38	Raynes	&(type (into '() (lazy-seq [1 2 3])))
13:38	sexpbot	⟹ clojure.lang.PersistentList
13:38	Raynes	That doesn't quite work like you might expect.
13:38	Raynes	&(into '() (lazy-seq [1 2 3]))
13:38	sexpbot	⟹ (3 2 1)
13:38	technomancy	rata_: you don't want just doall?
13:39	technomancy	you shouldn't care about the class, just whether its contents have bene realized
13:39	technomancy	*been
13:40	chouser	a PersistentList though is different than a seq. Knows its count, for instance.
13:40	chouser	& (apply list [1 2 3])
13:40	sexpbot	⟹ (1 2 3)
13:40	technomancy	true
13:41	rata_	technomancy: the bottleneck of my program was a the function rand-nth, then I change to use it vectors for fast random-access, but now the bottleneck is vec :(
13:42	thearthur	where can I find out more about the new contrib modular structure (google is failing me)?
13:43	thearthur	when i build from github i get a modules directory and am not sure what to add to classpath where in order ot use it
13:43	raek	rata_: if you are using lazy seqs, nothing will get computed until it is needed
13:43	Lajla	Chousuke, but where is that written?
13:44	raek	rata_: rand-nth or vec might be the first functions that need the values, and in the calls to them, the seq will be forced
13:44	Lajla	Missä se on kirjoitettu? =(
13:44	raek	rata_: you could try to add (doall ...) around each thing that returns a lazy-seq to see where the bottleneck really is
13:45	rata_	raek: I think it's easier to use visualvm to detect the bottleneck... it doesn't fail in saying that most of the time the program was computing vec or rand-nth
13:46	Chousuke	Lajla: nowhere, it's obvious
13:46	Chousuke	Lajla: the reader is not stupid, nor is pr :P
13:47	Chousuke	Lajla: though if you can find a way to get the reader to produce an illegal symbol, report that as a bug
13:49	Lajla	Chousuke, then where does it say that such symbols are illegal?
13:50	Lajla	I mean, whence can you deduce that because the reader can't read them they are illegal.
13:50	rata_	Raynes: I'm not using (into '() ...)
13:50	Lajla	a lot of lisps explicitly state that various data do not have a reader syntax, but are still valid data.
13:50	rata_	do you know of any other fn that can return a PersistentList from a LazySeq?
13:51	Chousuke	Lajla: that's the definition of illegal :P
13:52	Chousuke	rather, the docs state what is legal
13:52	Chousuke	and everything else, even if it happens to work when you call symbol, is illegal.
13:52	raek	rata_: what would be the benefit of making a PersistentList from a LazySeq? constant time count?
13:52	Lajla	Chousuke, maybe the docs conflict
13:53	Lajla	For instance, what do the docs say about the symbol? procedure
13:53	Chousuke	(doc symbol?)
13:53	clojurebot	"([x]); Return true if x is a Symbol"
13:53	Lajla	If the docs say at one hand that symbols cannot contain spaces, but at the other hand THAT THERE ABOVE
13:53	Lajla	THen obviously the docs contradict itself.
13:53	rata_	raek: no... I don't want it to be converted... but somewhere in my code a fn is converting it
13:53	Chousuke	Symbol, not a symbol
13:53	Lajla	Ahh
13:53	Lajla	Hmm
13:53	Chousuke	that means it returns true if it's an instance of the class.
13:53	Lajla	Ahhh
13:53	Lajla	So Symbol and symbol are destinct?
13:53	chouser	raek: Did you see that (apply list a-seq) returns a PersistentList?
13:54	Lajla	So, symbol in fact returns a Symbol?
13:54	Chousuke	yes
13:54	Lajla	Ahhh
13:54	Chousuke	Lajla: in a way, because you can have instances of Symbol that represent illegal symbols
13:54	Lajla	I can live with that.
13:54	Chousuke	because there's no validation (yet)
13:54	Lajla	Fuck symbols
13:54	Lajla	I like Symbols more.
13:54	chouser	rata_: sorry, that was for you not raek
13:54	Lajla	They can do more.
13:55	rata_	chouser: yes, but I'm not doing that either
13:55	chouser	rata_: how do you know you're getting a
13:55	chouser	PersistentList?
13:55	rata_	there's a function in my code that's converting my LazySeqs to PersistentLists
13:55	rata_	with class
13:56	raek	chouser: btw, is your extend-multimethod macro that you mentioned in your strange loop talk availabe somwhere?
13:56	chouser	raek: I'll look.
13:57	chouser	hm, is there a way to grep all versions of all files in a git repo?
13:59	rata_	I'm just using map, keep, conj and remove over my LazySeq afaik, yet I get a PersistentList
14:00	raek	conj will preserve the type, the other will produce lazy-seqs, IIRC
14:00	chouser	conj on a lazy-seq returns a Cons
14:01	rata_	yes, but Cons is not PersistentList
14:01	rata_	this conversion thing is so weird
14:04	raek	chouser: don't worry if you don't find it. i just thought it was an interesting idea, and I think it would be pretty easy to write myself
14:04	Chousuke	chouser: git has a grep command I think.
14:04	Chousuke	chouser: maybe you can use that?
14:06	Lajla	&(pr (symbol "I worship His Shadow"))
14:06	sexpbot	⟹ I worship His Shadownil
14:06	Lajla	nil
14:06	Lajla	?
14:06	Lajla	Ohhhh
14:06	Lajla	return value.
14:06	Lajla	You sort of would want like nil on failure or something.
14:06	Lajla	Or like
14:06	Lajla	nil on success, and some error message on failure.
14:06	Lajla	Yeah, that'd work too.
14:12	Lajla	&nil
14:12	sexpbot	⟹ nil
14:12	Lajla	(symbol? 'nil)
14:13	Lajla	&(read-str (pr-str (symbol "nil")))
14:13	sexpbot	java.lang.Exception: Unable to resolve symbol: read-str in this context
14:13	Lajla	Hmm...
14:13	Lajla	Chousuke, what'sthe name?
14:15	raek	read-string
14:15	raek	hrm. that's a bit asymmetric
14:22	Lajla	&(read-string (pr-str (symbol "nil")))
14:22	sexpbot	⟹ nil
14:22	Lajla	&(symbol? (read-string (pr-str (symbol "nil"))))
14:22	sexpbot	⟹ false
14:23	Lajla	raek, =(
14:23	Lajla	It is true
14:23	Lajla	raek, let's talk about our love.
14:25	tonyl	pr-str returns a string not a Symbol
14:25	tonyl	wait scratch that
14:26	tonyl	nil is not a Symbol :P it's a value
14:27	Chousuke	nil is null
14:27	tonyl	yeah
14:27	Chousuke	it's not a symbol at all
14:27	Chousuke	'nil is nil too
14:27	Chousuke	still not a symbol :)
14:28	jackdempsey	chouser: making my way through the joy of clojure. great stuff!
14:29	Chousuke	When was the dead-tree version supposed to be ready?
14:29	Raynes	I still haven't finished that book.
14:30	jackdempsey	yea, it's been a nice progression from programming clojure to practical clojure, and now some joy
14:31	jackdempsey	i need to stop reading and code something tho :-)
14:31	jackdempsey	anyone around SF and going to the meetup in a few weeks?
14:31	Lajla	tonyl, that was the point
14:31	Lajla	But (symbol "nil") is a symbol
14:31	Lajla	&(symbol? (symbol "nil"))
14:31	sexpbot	⟹ true
14:31	Lajla	Well, evaluates to
14:31	Lajla	technically it's a list
14:34	Lajla	Chousuke, what is the environment that eval uses though?
14:34	Lajla	Just the top level?
14:34	Lajla	&(eval '(and 1 2 3 4))
14:34	sexpbot	java.lang.SecurityException: You tripped the alarm! eval is bad!1
14:34	Lajla	Hmm
14:35	Lajla	Interestng
14:36	chouser	jackdempsey: thanks!
14:36	chouser	today I'm updating the lazy qsort code -- cgrand improved it.
14:37	Chousuke	Lajla: yeah
14:37	Lajla	Chousuke, does it also expand macros?
14:37	Lajla	And can you give it an environment argument?
14:37	chouser	Chousuke: Hopefully January or before for the book
14:37	Chousuke	Lajla: yes?
14:37	Chousuke	Lajla: no env arg
14:38	Chousuke	chouser: ok
14:38	Lajla	=(
14:38	Lajla	I want you as my environment baby
14:38	Lajla	If you get what I mean
14:38	Chousuke	:P
14:39	Lajla	Chousuke, I wasn't talking to you
14:39	Lajla	I was talking to myself.
14:39	Lajla	Narc
14:39	Lajla	You're so full of yourself.
14:39	tonyl	(symbol "nil") is a Symbol but once you pass it to pr-str it becomes a string "nil" which read-string evaluates to nil
14:40	jackdempsey	chouser: is there a site setup to report typos and such?
14:40	chouser	jackdempsey: yes, the Manning forums. But if I were you don't know that I'd bother right now.
14:41	jackdempsey	chouser: ok...? :-)
14:41	chouser	The version you can get is a bit out of date regarding typo fixes and stuff -- that's mainly what we're doing right now
14:41	jackdempsey	given they're probably all....yea
14:41	jackdempsey	k
14:41	chouser	the opportunity to contribute in that way has essentially passed
14:42	jackdempsey	cool
14:42	chouser	when then "final" version is out in a couple months here, we can start collecting errata for subsequent versions. :-P
14:42	apgwoz2	does clojars not allow you to change your password/key?
14:42	jackdempsey	thx btw for writing something beyond a beginning/primer. its hard to get deeper into newer languages at times, so the pace and depth of getting into things has been great
14:42	jackdempsey	cool
14:42	chouser	but hopefully anything you're finding now has already been fixed
14:43	jackdempsey	yea i'd imagine so
14:43	Chousuke	damn ustream. Causes Flash to gobble gigabytes of memory :/
14:43	chouser	jackdempsey: thanks, glad you're enjoying it.
14:43	Chousuke	I just closed firefox and Freed 2GB :P
14:43	apgwoz2	i should rephrase my question, is clojars currently broken when it comes to editing password/public key?
14:55	dnolen	apgwoz2: it seemed to be working last time I had to do that.
14:56	apgwoz2	dnolen: hmmm. i'm getting an error for both email address and password not being set... but even when they're not.
14:56	apgwoz2	oh well
14:56	apgwoz2	in lieu of just publishing to clojars, what's the best way to depend on another library with leiningen?
14:56	dnolen	apgwoz2: lein install
14:57	dnolen	apgwoz2: just get a checkout of the library source, and run lein install from it's dir
14:58	apgwoz2	ah, ok. and then just add it as a dependency?
14:58	dnolen	apgwoz2: yup
14:58	apgwoz2	easy enough
14:58	apgwoz2	thanks
14:59	shafiahmedbd	Hi
15:02	shafiahmedbd	Do you know of any clojure web scraper?
15:02	apgwoz2	shafiahmedbd: checkout tag soup
15:03	shafiahmedbd	Thanks
15:03	apgwoz2	there's also https://github.com/brool/beaujiful-soup, which is a more clojure like lib for using tag soup
15:05	bobo_	shafiahmedbd: enlive can be used for scraping aswell
15:07	Lajla	tonyl, sure, but were were testing that.
15:07	Lajla	Maybe a reader syntax like \|nil\| would be nice.
15:07	Lajla	Tell Rich to add it.
15:07	Lajla	I will hug you all day long.
15:13	raek	shafiahmedbd: enlive even uses tagsoup under the hood
15:14	dnolen	shafiahmedbd: enlive is probably best for easiest scraping, you can pull out elements with CSS3 syntax.
15:15	Lajla	&(eval 3)
15:15	sexpbot	java.lang.SecurityException: You tripped the alarm! eval is bad!1
15:15	dnolen	CSS3-like, with some interesting additions
15:15	Lajla	How can I get eval to work?
15:15	raek	Lajla: java -jar clojure.jar on your own computer
15:16	Lajla	=(
15:16	Lajla	But I wamnt to steal your cycles.
15:16	Lajla	I don't have the JVM installed right now.
15:27	mattmitchell	in ruby, you can do something like: my_hash[:key] \|\|= [] -- which sets :key to a new array if :key is nil, is there something like this in clojure?
15:30	Lajla	mattmitchell, if there isn't, you can write a macro I guess.
15:31	Lajla	But I guess it will more be like
15:31	raek	mattmitchell: (assoc m (get m key []))
15:31	Lajla	returning nil if it's not nil, and already exists.
15:31	Lajla	And return the updated, if it didn't already exist.
15:32	raek	(assoc m key (get m key []))
15:32	raek	some had a neat example using update-in and fnil
15:33	mattmitchell	excellent thanks
15:34	mattmitchell	would someone mind taking a stab at this? https://gist.github.com/708130
15:34	mattmitchell	i'm messing with reduce now, just trying to learn how it works. i think reduce is the right way?
15:35	raek	I guess you could use merge-with in this case
15:36	raek	,(merge-with concat {:id 1, :f ["a"]} {:id 1, :f ["b"]})
15:36	clojurebot	java.lang.IllegalArgumentException: Don't know how to create ISeq from: java.lang.Integer
15:36	raek	oh, sorry
15:37	raek	hrm
15:37	mattmitchell	don't be, merge-with is something i'm looking into now
15:38	raek	it would work if you had the data on the form {1 ["a"]} {1 ["b"]}
15:39	mattmitchell	raek: i see
15:40	dnolen	,(merge-with concat {1 "a"} {1 "b"} {2 "c"})
15:40	clojurebot	{2 "c", 1 (\a \b)}
15:41	dnolen	,(let [f (fn [a b] (if (vector? a) (conj a b) (conj [a] b)))] (merge-with f {1 "a"} {1 "b"} {2 "c"}))
15:41	clojurebot	{2 "c", 1 ["a" "b"]}
15:44	mattmitchell	dnolen: thanks, i'll have a play with that
15:44	raek	,(reduce (fn [m [id f]] (assoc m id (conj (get m id []) f))) {} [[1 "a"] [1 "b"] [2 "c"]])
15:44	clojurebot	{2 ["c"], 1 ["a" "b"]}
15:45	raek	,(reduce (fn [m {:keys [id f]}] (assoc m id (conj (get m id []) f))) {} [{:id 1, :f"a"} {:id 1, :f "b"} {:id 2, :f"c"}])
15:45	clojurebot	{2 ["c"], 1 ["a" "b"]}
15:47	raek	,(map (fn [[id fs]] {:id id, :f (vec fs)}) (reduce (fn [m {:keys [id f]}] (assoc m id (conj (get m id []) f))) {} [{:id 1, :f"a"} {:id 1, :f "b"} {:id 2, :f"c"}]))
15:47	clojurebot	({:id 2, :f ["c"]} {:id 1, :f ["a" "b"]})
15:47	raek	there. :)
15:47	dnolen	nice
15:48	raek	I would prefer using for here, but it gets messy do edit code of this length in one line...
15:48	mattmitchell	nice! that's a full days study lesson for me.
15:48	raek	(for [[id fs] result-of-reduce] {:id id, :f (vec fs)})
16:08	raek	hrm, the order doesn't matter, you could replace the (assoc m id (conj (get m id []) f)) part, with (update-in m [id] conj f), since nil (the default value for get) work as () with conj
16:09	mattmitchell	raek: ok i'll try that. now what if I had hash-maps that had lots of keys, but I only wanted to append the :f key into a vector, but keep the rest?
16:09	mattmitchell	raek: for a little background... this is a sql result set, using joins
16:13	raek	mattmitchell: how should {:id 1, :f "a", :x "y"} and {:id 1, :f "b", :x "z"} be merged?
16:13	mattmitchell	raek: oh they will always be the same values
16:13	raek	mattmitchell: also, have you checked out the new version of ClojureQL?
16:13	mattmitchell	raek: no, only using the clojure.contrib.sql
16:14	mattmitchell	raek: i'll check out ClojureQL
16:14	raek	http://bestinclass.dk/index.clj/2010/11/clojureql--1.0.0-now-in-beta.html
16:15	mattmitchell	that's looking good :)
16:23	Lajla	raek,
16:23	Lajla	if I paid you handsomely
16:23	Lajla	would you write a formal spec of clojure?
16:23	Lajla	That answers all my problems
17:31	Lajla	Chousuke, why aren't you in casual?
17:31	Lajla	We miss you.
17:31	Lajla	We're talking about you're high literary standard now.
17:45	Chousuke	Lajla: your :P
17:45	Lajla	Chousuke, that is because mine is bad. =(
17:45	hippiehunter	Can someone point me in the right direction? I'm trying to define and throw an exception, but clojure complains that it cant find the class. I'm using lein and I've tried setting the exception classes to be aot compiled but without any luck.
17:51	raek	hippiehunter: has the .class file appeared in the classes/ directory?
17:52	hippiehunter	yes
17:52	raek	have you imported it in the clojure code?
17:53	hippiehunter	i have (:use [bla.bla myexception])
17:53	hippiehunter	in my ns
17:53	raek	(although, that shouldn't be needed, if you use the fully qualified name)
17:53	raek	ah, since it's a java class and not a var in a namespace, you have to :import it
17:53	raek	(:import bla.bla.myexception)
17:54	raek	(assuming "myexception" is the name of the generated class)
17:54	raek	i.e. you should have a classes/bla/bla/myexception.class file
17:54	hippiehunter	now it just complains at the :import instead of where i try to instance it
17:54	hiredman	hippiehunter: the problem is the clojure code that throws the exception is being compiled before the code that generates the exception
17:55	hiredman	you can use clojure.lang.Reflect (Relector?) to get around it
17:55	hippiehunter	in my project.clj I put the exception classes first in the aot list
17:55	hippiehunter	an based on the output to the console its making them first
17:55	hippiehunter	and*
17:55	Raynes	Reflector is right
17:59	hippiehunter	when i do an import do i have to replace the -'s with _'s?
18:00	hippiehunter	looks like yes
18:01	hippiehunter	that is mildly unpleasant
18:05	hiredman	you can't have - in a java class name
18:07	hippiehunter	it seems inconsistant that i can define things with - in clojure but depending on how i use them it might not work
18:08	hiredman	if you define something for java interop (a java class) you have to follow java rules
18:10	hippiehunter	I would agree with you but then it should be throwing an error at definition time when i do the :gen-class
18:11	hippiehunter	or possibly when I do (:import [bla.bla my-exception-with-dashes])
18:12	hippiehunter	well i suppose it is throwing an error on the import its just not a very helpfull one, anyway thanks for the assistance
18:24	harishtella	anyone know why I can't use "." as the function in map? (map . (repeat 2 javaclass) '(javafn javafn))
18:25	Raynes	Because '.' is a special form.
18:25	Raynes	Special forms and macros cannot be used in places where functions can, like as the argument to map.
18:25	harishtella	any other way to collect results from calling function on a java obj
18:25	harishtella	different functions
18:28	raek	instead of (map .method sequence-of-objects) you have to write (map #(.method %) sequence-of-objects)
18:28	raek	i.e. create an anonymous function that does the interop call
18:30	harishtella	oh got it, thanks
18:46	hiredman	. is not a function, thats why you can't use it as one
18:47	harishtella	anyway a can eval a set of symbols without applying the first symbol as function rule (foo bar) ; where foo and bar are strings
18:47	harishtella	I want a seq of strings
18:49	raek	if you want to evaluate an expression that is given in string form, you could do something like (eval (read-stirng the-string))
18:50	raek	but if you are writing a code-evaluating bot or something, you should use a sandbox lib (like clojail)
18:51	raek	harishtella: could you give an example of what your input look like, and what you want to get called?
18:55	harishtella	I should just ask my real question I trying to figure out;
18:56	harishtella	(def foo "Green") (map #(. foo %) '(toUpperCase toLowerCase))
18:56	harishtella	and say I want a list back like ("GREEN" "green")
20:07	ossareh	is anyone able to explain why my meta data :foo exists sometimes and not others? https://gist.github.com/708322
20:08	ossareh	clj 1.2 fwiw
20:10	raek	to attach metadata, either do (defn ^{...} foo "docs" ...) or (defn foo "docs" {...} ...)
20:10	raek	not the lack of ^ in the latter case
20:10	raek	strange behaviour, though...
20:10	technomancy	does anyone use the lein interactive task?
20:12	technomancy	well, if you do, try the latest git master; it's a lot nicer.
20:13	ossareh	so I guess in the case where I have no "docs" (the fn is super simple and the name describes it accurately) I have to do the ^{} version ?
20:13	ossareh	technomancy: I'll take a look - I'm not sure if I'm ready for a major upgrade though
20:14	ossareh	last time I did that I lost a fair amount of time :/ (1.1 -> 1.2)
20:14	technomancy	ossareh: you can keep 1.3.1 around for regular use; it's easy to just experiment with both in parallel
20:14	ossareh	I'm on 1.2
20:14	technomancy	right; you don't need to replace what you have is what I mean
20:14	ossareh	... partly because that is what lein gives me ;)
20:15	technomancy	oh, clojure 1.2?
20:15	technomancy	yeah, you can use lein with any clojure version, no upheval required
20:16	ossareh	yup, am aware of that - I'll give 1.3 a shot in the morning - right now I can just leave my meta data angle out
20:17	ossareh	raek: same flakiness https://gist.github.com/708322
20:52	talios	'lo
20:53	ossareh	what is the recommended way to get clojure mode into emacs these days? I last used elpa
21:17	devinus	will clojure begin to implement more basic core functions for e.g. parsing integers and such as part of it's transition to clojure in clojure ?
21:19	Lajla	devinus, that is your burning issue with a langauge that does not yet support TCO?
21:19	Lajla	I'm so going to tell chousuke, and then he'll eat you. n.n
21:19	Lajla	And I will win
21:20	Chousuke	devinus: probably not until there's a real need for it.
21:21	Chousuke	Lajla: and you need to stop being so annoying :P
21:23	devinus	Chousuke: there was a blog post i read, i think it was coder who says py, on his thoughts on clojure i've gotta agree with. i don't care at all that it uses the jvm, i just hate how much it seems you use the jdk
21:23	devinus	need a cdk :P
21:24	Lajla	java digit ... konvention?
21:24	Lajla	What does the k stand for?
21:24	Lajla	devinus, you wil answer this quaestion, which since the dawn of times has been etched upon my mind.
21:24	Lajla	For long I searched the answers which I need, so that I may give purpose to my own existence.
21:25	Lajla	I journeyed long across the stars, bore witness to the rise and fall of many a civilization, beheld the birth of negative suns.
21:25	Chousuke	You're being stupid on purpose.
21:25	Chousuke	please just stop.
21:25	Lajla	I just want ot know what jdk stands for. =(
21:26	Chousuke	google it :P
21:26	Chousuke	devinus: Writing wrappers for the jdk is not very productive.
21:26	hiredman	Chousuke: you can put him on ignore, I have, and I have clojurebot ignoring him, it's great
21:27	Chousuke	devinus: but if there's a real need for such a library I'm sure it'll get written :)
21:27	devinus	Chousuke: sure, it'd feel pretty tedious
21:27	Chousuke	But now I need to get some sleep :P
21:27	devinus	gnight
21:28	Chousuke	Also, I wish the ustream flash player wasn't so horrible.
21:28	Chousuke	it gobbled up 2.5GB of memory and now my system feels like it's going through tar while everything is fetched from swap into memory again
21:29	Chousuke	It must be doing something idiotic like caching the whole stream in memory or something
21:29	Chousuke	because it never stops growing.
21:29	Chousuke	anyway, good night :P
21:46	krumholt	at what time will calls to java static methods evaluated?
21:46	krumholt	+be
21:55	krumholt	where can i find the source code for the dot macro?
21:55	hiredman	not a macro
21:56	Raynes	krumholt: It's a special-form, of which you cannot find the source. The implementation would be in Java.
21:56	krumholt	Raynes, and can i find the java code somewhere?
21:57	Raynes	Sure, but I have no clue where. :\
21:57	hiredman	it's a special form so it is implemented in the compiler
21:57	Raynes	Right, the compiler.
21:58	krumholt	ok thanks
21:59	Raynes	krumholt: All of the Java stuff is here: https://github.com/clojure/clojure/tree/master/src/jvm/
22:01	paulrosania	https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/Compiler.java
22:01	paulrosania	L692
22:01	paulrosania	Good luck :)
22:05	Raynes	My eyes!
22:06	paulrosania	there's a lot of commented-out code in there
22:22	ossareh	zz... 1.3.0-alpha3 returns nil on (meta some-fn-with-md)
22:22	ossareh	previously it would at least return :doc , :file, etc.
22:34	ossareh	OK, fixed - I was not prefixing my fn with #' - i.e. (meta #'some-fn-with-md)
22:49	krumholt	ok i found my problem
22:49	krumholt	macroexpand will create static fields?
22:50	krumholt	so if a class has static fields they will be created at macroexpansion time?
22:50	hiredman	nope
22:52	joeyd81	hi, in which clojure channel should beginners go?
22:53	krumholt	ok import creates static fields?
22:53	hiredman	no
22:54	krumholt	hiredman, i wrote a simple testclass http://pastebin.com/t9QLtfQp
22:54	technomancy	joeyd81: here is fine
22:54	hiredman	krumholt: good for you
22:54	krumholt	evaluating (ns myns (:import Test)) will print output to the repl
22:55	krumholt	the string "output"
22:55	krumholt	or "Test"
22:56	hiredman	that is not "creating" the static field, that is initializing, I suggest you google "static field initialization"
22:56	krumholt	ok so import initializes the static fields?
22:57	hiredman	no
22:57	hiredman	which is why I suggested you google and read
22:57	technomancy	ah static; a perfect "you keep using that word; I do not think it means what you think it means" example.
23:04	krumholt	ok, so evaluation (ns myns (:import blub.Test)) will create the static fields of Test?
23:04	krumholt	i was not expecting that
23:04	hiredman	it does not
23:04	krumholt	i just tried
23:05	hiredman	that is not "creating" the static field, that is initializing
23:05	krumholt	ok it initizlises them. still not what i expected
23:06	hiredman	well, then you don't know anything about the jvm
23:07	krumholt	if i import something in java that will not initialise the static fields. the first creation of an object will
23:09	krumholt	or a static method call
23:13	joeyd81	Hi, I am a beginner trying to learn clojure by writing simple programs, for example all permutations of a collection. Can somebody tell me where I am going wrong in function "permute" on http://pastebin.com/LCSR3nwM
23:14	technomancy	joeyd81: first thought: each defn should be independent at the top-level, not nested
23:15	technomancy	joeyd81: the formatting of the code makes it hard to follow
23:16	technomancy	inside my-fun you should use destructuring instead of let-binding first and rest explicitly
23:17	technomancy	flat1 and my-fun would be easier to test if they were top-level defuns as well; perhaps private ones
23:17	technomancy	you probably want apply concat instead of just concat on line 33
23:17	technomancy	is that enough? =))
23:18	joeyd81	thanks for the feedback, I will study it, can you just clarify what you mean by " should use destructuring instead of let-binding..."
23:19	technomancy	sure. (let [[f & rst] param] ...) is the same as (let [f (first param), rst (rest param)] ...)
23:20	joeyd81	ok, cool thanks, I will be back here to seek help if I can't make progress by noon tomorrow, good night folks
23:20	technomancy	joeyd81: it will be easier to debug if you write and test the smaller functions first
23:21	technomancy	and then compase them into larger pieces once you know they work
23:21	technomancy	*compose
23:21	joeyd81	I usually do that in the repl
23:21	technomancy	sure; I just mean make sure the little pieces work before bothering to stitch them together
23:28	tramzee	exit
23:28	tramzee	exit
23:28	tramzee	quit
23:33	krumholt	ok i found my problem. The RT looks up classes in the classForName method with Class.forName(name, true, baseLoader()) which will initialise the class. is there a reason this is done for import expressions?