#clojure – 2008-12-28

2008-12-28

00:07	kabny	i see
00:12	kabny	what doe sit mean to write (. hmm some) as opposed to (.some hmm)?
00:16	dreish	The latter turns into the former at macro expansion time. They're equivalent.
00:36	kabny	what would be best suitable for a GUI, agents or refs?
00:52	kabny	what would be best suitable for a GUI, agents or refs?
01:00	kabny	anyone using contrib.sql?
01:02	kabny	how do you refer to a database since with-connection returns nil?
01:22	chrisdone	clojurebot: help
01:22	clojurebot	macro help is http://clojure-log.n01se.net/macro.html
01:22	chrisdone	clojurebot: source
01:22	clojurebot	Titim gan �ir� ort.
01:22	chrisdone	mmkay
01:22	chrisdone	clojurebot: commands
01:22	clojurebot	It's greek to me.
01:29	chrisdone	clojurebot: eval (+ 1 1)
01:29	clojurebot	Gabh mo leithsc�al?
01:37	eric-at-home	,(+ 1 1)
01:37	clojurebot	2
01:37	eric-at-home	kabny: I am using contrib.sql.
01:38	eric-at-home	oh, kabny already left :-(
09:50	Lau_of_DK	Zzzzz
09:51	Raynes	zzzzZ
11:34	vseguip	hi all
11:35	danlarkin	vseguip: howdy
11:35	vseguip	I'm new to clojure
11:35	vseguip	I've been plating with it for some univerity assignment
11:36	vseguip	I've been trying to optimize my algorithims with some hints as per http://clojure.org/java_interop
11:36	vseguip	however I'm getting very different timings
11:36	vseguip	from those in the page
11:37	vseguip	for intance
11:37	vseguip	de foo2 function
11:38	mibu	how much different is it?
11:38	vseguip	an order of magnitude
11:38	vseguip	(time (foo2 100000))
11:38	vseguip	"Elapsed time: 0.908077 msecs"
11:38	vseguip	100000
11:38	danlarkin	well you've got a different computer from the one on which this computer was compiled
11:39	vseguip	I have a string ina Java array
11:39	mibu	that's well under a msec. doesn't mean anything.
11:39	vseguip	yep
11:39	vseguip	but for instance
11:39	vseguip	I would have thought that this would be faster
11:40	vseguip	(time (clojure.core/amap dicc i ret (aget ret i)))
11:40	mibu	different computer, different java version, background programs all can affect the speed.
11:40	vseguip	"Elapsed time: 18.029456 msecs"
11:41	vseguip	(count dicc)
11:41	vseguip	13189
11:41	vseguip	I realize that
11:41	vseguip	but 20 ms to traverse a Java array seems weird
11:42	vseguip	with only 13189 positions
11:42	vseguip	would that be normal?
11:43	mibu	vseguip: it could
11:44	vseguip	(fairly new machine Intel(R) Core(TM)2 Duo CPU T7250 @ 2.00GHz with 4gb ram, java 6, ubuntu)
11:44	vseguip	(clojure-svn rev 1162)
11:49	danlarkin	vseguip: whip up a reproducible test and I'll tell you how fast it is on my machine
11:50	vseguip	(def arry (into-array (range 10000)))
11:50	vseguip	(time (clojure.core/amap arry i ret (aget ret i)))
11:51	vseguip	I'm doing it in 2 steps
11:51	vseguip	so as to only time
11:51	vseguip	amap
11:51	vseguip	not the array conversion
11:51	danlarkin	10ms for me
11:52	vogelrn	3ms here
11:52	vseguip	13ms
11:52	vseguip	for me
11:53	vseguip	vogelrn: what is your setup?
11:54	vogelrn	uhhh core 2 duo E6600, 2gb ram, java 6, ubuntu
11:57	vseguip	simiilar to mine
11:57	vseguip	wht clojure version?
12:01	vogelrn	whoops, I forgot, I haven't updated in a while, been on my laptop recently, let me update and see if it gets slower (I'm on 1147)
12:04	vogelrn	nope, still the same speed
12:04	vogelrn	well, updating to latest that is
12:07	arbscht_	3.5ms - core2 duo E6750, 2G, openjdk 1.6.0, debian, clojure rv 1185
12:10	vseguip	mm
12:10	vseguip	I'm using sun6-java
12:10	vogelrn	so am I
12:11	Raynes	Downloading the JDK on dialup is no fun :\|
12:11	danlarkin	Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_16-b06-284)
12:11	Lau_of_DK	Just wanted to make sure that everyones aware that clojure-mode has been forked and it now being worked upon from http://github.com/technomancy/clojure-mode/tree/master
12:12	arbscht_	Lau_of_DK: fantastic
12:12	vseguip	vogelrn: using server jvm?
12:12	vogelrn	the default is client, no? I haven't added the flag myself
12:13	vseguip	yep
12:13	vseguip	defualt is clinet
12:13	vseguip	using it from emacs/command line/repl?
12:13	vogelrn	emacs
12:14	vseguip	me too
12:15	vseguip	clojure trunk I guess?
12:16	mibu	anyone knows if there is a splice or flatten function in the contrib?
12:16	vseguip	flatten
12:16	vseguip	is there
12:17	mibu	where?
12:17	vseguip	in clojure.contrib.seq-utils
12:17	mibu	thanks
12:18	vogelrn	I mean, you might try updating to the latest revision, it's slightly possible that it got worse in 1162 and then better again afterwards, if unlikely :P
12:19	vseguip	according to svn up
12:19	vseguip	latest revision in 1162
12:20	vseguip	:-\|
12:20	vogelrn	it got changed
12:20	vogelrn	http://clojure.googlecode.com/svn/trunk clojure
12:21	vseguip	:-o
12:22	vseguip	OTOH is there a way to "realize" a lazy seq recurisively other then printing it?
12:23	mibu	vseguip: dorun or doall
12:24	vseguip	it doesn't seem to do it recursively
12:24	mibu	vseguip: what do you mean recursively?
12:25	vseguip	let's suppose you have a lazy seqs of lazy seqs
12:25	vseguip	I would like it to realize the top level lazy seq
12:25	vseguip	and then the inner lazy seqs
12:25	vseguip	etc
12:26	vseguip	I think I will do a simple func to do this
12:26	mibu	again, you can use doall or dorun. just map them (map doall some-seq)
12:27	vseguip	mibu: yup but it would be nice to have a recurive function to do this
12:27	vseguip	will try and ree
12:27	vseguip	and reachback
12:36	vseguip	(defn realize [xs]
12:36	vseguip	(if (seq? xs)
12:36	vseguip	(doall (map realize xs))
12:36	vseguip	xs))
12:36	vseguip	seems to work
12:40	mibu	vseguip: do you happen to know if there is also splice somewhere?
12:44	vseguip	what does splice do?
12:45	vseguip	are you operating on strings, seqs, vecs ?
12:46	kotarak	For vecs there is subvec.
12:46	kotarak	For seq: (take n (drop m s))
12:50	vseguip	same speed
12:51	vseguip	:(
12:54	chrisn	what is the most efficient way to go from a sequence to a typed array?
12:56	vseguip	chrisn: not sure but (into-array)
12:56	vseguip	seems the way
12:56	chrisn	thanks, I will check that out.
12:56	chrisn	Looking into the api more, I need it to go into java.nio Buffer of some sort
12:58	chrisn	Is there a typeof operator?
12:59	kotarak	chrisn: (class ...)
12:59	kotarak	Or better: (instance? TheClass the-thing)
13:00	chrisn	awesome
13:00	danlarkin	also isa?
13:01	kotarak	danlarkin: I think isa? is more for the hierarchy stuff.
13:01	danlarkin	(doc isa?)
13:01	clojurebot	Returns true if (= child parent), or child is directly or indirectly derived from parent, either via a Java type inheritance relationship or a relationship established via derive. h must be a hierarchy obtained from make-hierarchy, if not supplied defaults to the global hierarchy; arglists ([child parent] [h child parent])
13:02	kotarak	(isa? TheClass (class the-thing)). instance? is shorter.
13:02	danlarkin	instance? checks only direct inheritance, isa? does full inheritance trees
13:03	kotarak	? What is a full inheritance tree?
13:05	danlarkin	say C inherits from B which inherits from A
13:05	danlarkin	and a is an instance of A
13:06	danlarkin	(instance? C c) is true, (isa? c C) is true, (instance? A c) is false, (isa? c A) is true
13:06	danlarkin	right?
13:07	kotarak	Obviously not:
13:07	kotarak	1:1 user=> (isa? "string" String)
13:07	kotarak	false
13:07	kotarak	1:2 user=> (isa? (class "string") String)
13:07	kotarak	true
13:07	kotarak	1:3 user=> (instance? Object "string")
13:07	kotarak	true
13:07	kotarak	1:4 user=> (instance? String "string")
13:07	kotarak	true
13:08	danlarkin	Hm, guess I was mistaken... not the first time!
13:10	mibu	I have this unexplained error when I use a macro. Everything works just fine as long as I don't you the macro in a function.
13:11	mibu	; permutations without repetitions (r choices from n)
13:11	mibu	(defmacro permutations [n r]
13:11	mibu	(let [locals (take r (repeatedly gensym))
13:11	mibu	for-range (apply concat (for [i (range r)] [(nth locals i) `(range ~n)]))]
13:11	mibu	`(for [~@for-range :when (= ~r (count (distinct [~@locals])))] [~@locals])))
13:11	mibu	; permutate a vector without repetitions (r choices from vector v)
13:11	mibu	(defn permutate [v r]
13:11	mibu	(let [perms (permutations (count v) r)
13:11	mibu	map-perm (fn [perm] (map #(nth v %) perm))]
13:11	mibu	(map map-perm perms)))
13:11	mibu	(lisppaste don't work)
13:12	mibu	(permutate [10 20 30 40 50] 3)) spits java.lang.ClassCastException: clojure.lang.Symbol cannot be cast to java.lang.Number (NO_SOURCE_FILE:229)
13:13	mibu	anyone has any idea what's going on?
13:13	arbscht_	mibu: use paste.lisp.org please
13:13	mibu	arbscht_: it doesn't work.
13:14	mibu	arbscht_: some kind of netsplit. lisppaste8 isn't in the channel (at least over here)
13:14	arbscht_	you can paste it and broadcast the url manually :)
13:15	mibu	arbscht_: how do I get the url?
13:16	chrisn	how do I use a static function as a first class function?
13:16	arbscht_	mibu: when you make a paste, it will create a page at some url, which you will be redirected to
13:17	mibu	chrisn: #(.lowercase %)
13:17	chrisn	static, not member
13:18	chrisn	But that would work. I was trying to avoid wrapping in another function
13:18	chrisn	seems pointless
13:18	Chousuke	you have to wrap java methods.
13:18	chrisn	even static functions?
13:18	Chousuke	since they're not first class functions.
13:18	Chousuke	even them.
13:18	mibu	arbscht_: nope, it sent me to a blank with the same url of the submit
13:19	arbscht_	mibu: fine, use some other paste service then. it makes code much easier to read and copy :)
13:21	mibu	http://pastebin.com/md89a240
13:22	mibu	anyone with a suggestion? I'm busting my head with this for hours now.
13:23	Chousuke	gah I hate that pastebin
13:23	Chousuke	the colour scheme is horrible
13:23	Raynes	www.codepad.org
13:24	Raynes	Has a Scheme setting.
13:24	mibu	http://codepad.org/jbDEzu1x
13:24	Chousuke	why is your permutations a macro?
13:25	mibu	chousuke: how would you have written it?
13:25	Chousuke	as a function?
13:25	Chousuke	is there a reason that it is a macro?
13:25	mibu	chousuke: yeah, how? I'm using a variable number of locals in the for range.
13:26	mibu	(for [x1 (range 6) x2 (range 6) x3 (range 6)] ...) for [6 3] ; (for [x1 (range 6) x2 (range 6)] ..) for [6 2]
13:27	Chousuke	hmm.
13:27	mibu	btw: if you guys know of a better permutations implementation, I'm all ears.
13:29	mibu	outside of a function, it just works. I don't understand why when I call it, it spits this error. I tried tracing it to the Java code, but to no avail.
13:33	chrisn	(permutations (count [1 2 3]) 4)
13:33	chrisn	nil
13:33	chrisn	(I think you are double evaluating something
13:34	mibu	if I don't call it from inside the function, it works. If I fix r, it works. If I expand it by hand and eval it, it works.
13:34	mibu	chrisn: (permutations [1 2 3 4] 3). what you called is not a vector and has too small of an r.
13:35	mibu	chrisn: I meant an r that is too large - r should be <= (count v)
13:36	chrisn	yeah, I just tried with a valid r and it was fine
13:36	chrisn	Trying to check out the macroexpand code
13:36	mibu	chrisn: you managed to run it without an error from a function?
13:36	chrisn	hell no
13:36	chrisn	just typing it into my repl
13:36	mibu	oh :-(
13:38	chrisn	user> (def v [1 2 3])
13:38	chrisn	#'user/v
13:38	chrisn	user> (def r 2)
13:38	chrisn	#'user/r
13:38	chrisn	user> (permutations (count v) r)
13:38	chrisn	That doesn't work
13:38	chrisn	So you can break it just by using symbols in any sense, not just in a function
13:39	chrisn	breaks macroexpand, too
13:39	chrisn	weird
13:39	Chousuke	mibu: I think the problem is with your n
13:39	mibu	I figured it has something to do with r. Use a fix r, and it works.
13:39	Chousuke	instead of the evaled value of (count v), an actual "(count v)" is passed
13:40	kotarak	macros cannot depend on runtime information.
13:40	kotarak	(count v) is runtime info
13:40	kotarak	Chousuke is right. The macro sees the form (count v) and not the value.
13:40	mibu	chousuke: doesn't ~n eval it?
13:41	Chousuke	no, ~n expands to (count v)
13:41	chrisn	The error is in r
13:42	mibu	ha...
13:42	chrisn	nope
13:42	chrisn	wrong
13:42	mibu	that's one hell of a gotcha.
13:42	chrisn	hmm...
13:42	chrisn	whoa
13:43	mibu	kotarak: you said it's runtime info, how so?
13:43	mibu	chousuke: wouldn't a (count v) still eval correctly in the context of the father function?
13:43	kotarak	mibu: ok, the argument applies, but to the other parameter.
13:44	chrisn	only if the arguments were known at compile time.
13:44	chrisn	In your function, they are symbols, not compile time constants
13:44	Chousuke	hm, no wait
13:44	kotarak	mibu: you get r as a function parameter, but use it in your macro.
13:44	kotarak	but the macro sees r and not the parameter value
13:44	chrisn	right. The compiler would have to generate infinitely many functions for this to work.
13:44	mibu	kotarak: wait wait, I'm not following. r is not bound to what permutate sets it to be?
13:45	kotarak	Yup.
13:45	kotarak	The compiler doesn't know that at compile time.
13:45	mibu	kotarak: I fail to see how it's a problem
13:46	kotarak	(let [r 5] (permutations (count v) r)) The macro sees the symbol r, not the value 5.
13:46	mibu	oh, I get it. It's not the evaluated r. How do I bypass this?
13:47	kotarak	You can't, I presume.
13:47	chrisn	Either your arguments are known at compile time or you write a function as Chousuke suggested.
13:47	mibu	kotarak: is there something more elegant than (eval r)?
13:47	mibu	chrisn: it wouldn't be easy to write a function like that.
13:47	Chousuke	mibu: add (println r) to the top of your macro to see the problem
13:48	Chousuke	mibu: when called directly, you get "3" printed, but when you call from a function, it prints "r"
13:48	chrisn	I didn't say anything about easy or hard. You don't have other options, mibu.
13:48	kotarak	mibu: (eval r) also doesn't work.
13:48	mibu	chousuke: I got the problem now. Now, I'm trying to understand what is the proper way to fix it, and how to properly write macros in the future.
13:49	kotarak	mibu: macros may only depend on information known at compile time. A function parameter is not known at compile time.
13:49	kotarak	mibu: you have to find a different algorithm, which doesn't use for.
13:50	chrisn	mibu, you are missing the point. Macros are compile time code. They can't work if they can only be expanded at run time. Your macro is fine. Its the use case.
13:50	mibu	kotarak: you're right.
13:50	mibu	kotarak: but it was such a nice idea. ;-)
13:50	kotarak	mibu: there are a lot of nice ideas. ;) Have lots of those myself. ;)
13:51	mibu	well, this mistake was well worth the lesson it taught me about macros.
13:56	mibu	anyway, thanks for your help guys.
13:59	kabny	I think people overuse macros in lisp
14:00	danlarkin	kabny: I agree
14:00	kabny	so often I see examples of macros where a function would d an be much cleaner and simpler
14:00	kotarak	If you don't need to control evaluation, you don't need a macro.
14:00	Chousuke	I wonder what's wrong with my aquamacs
14:01	Chousuke	it always opens two windows at startup
14:01	Chousuke	it's annoying
14:01	danlarkin	Chousuke: scratch?
14:02	Chousuke	yes. twice.
14:02	danlarkin	gotta delete that sheeeaaaat
14:02	danlarkin	haven't figured out how to make it not open aside from deleting it
14:02	Chousuke	whoops
14:03	Chousuke	wiped my config
14:03	Chousuke	good thing it's backed up in git :P
14:04	Chousuke	danlarkin: and I don't mind it opening scratch but why does it open it twice?
14:04	Chousuke	and in different windows.
14:04	Chousuke	if I wipe my config it works normally :/
14:04	danlarkin	well I've figured it out then, a problem with your config!
14:05	Chousuke	yes, but WHAT.
14:06	mibu	emacs is a conspiracy to keep programmers occupied with their config files. ;-)
14:08	ivan	indeed
14:09	ivan	anyone have basic clojure syntax highlighting for IDEA 8?
14:10	mibu	ivan, if you want something really basic you can use highlighting of other lisp formats.
14:11	danlarkin	ivan: there's an IDEA plugin... somewhere
14:11	ivan	the generic syntax highlighter that doesn't really work?
14:12	danlarkin	can't say, I haven't tried it
14:12	kabny	when doing GUIs what is most appropriate, agents or refs?
14:14	mibu	kabny: it really depends, but if you must have a general answer then agents. GUI is mostly asynchronous.
14:17	Chousuke	ah, hm
14:18	chrisn	mibu: http://pastebin.com/m10ecab20
14:19	mibu	chrisn: thanks!
14:20	chrisn	I forgot contains_dups
14:20	chrisn	But it is stupid
14:20	chrisn	(defn contains_dups [seq]
14:20	chrisn	(< (count (distinct seq)) (count seq)))
14:23	chrisn	It would be way more efficient to catch duplicates in the for statement
14:24	chrisn	And my order is different than yours
14:24	chrisn	But the result is the same
14:24	chrisn	Also, if I knew recur that would be a better solution
14:24	Chousuke	for some reason, (setq 'viper-mode t) is causing it
14:25	mibu	chousuke: the double scratch?
14:25	Chousuke	yeah
14:26	mibu	chrisn: what I like about my version is that with a simple for that declares what needs to be the result, you finish the task.
14:26	chrisn	your version is definitely ideal.
14:27	chrisn	but in reality for expands into a bunch of recur statements, so I am damn close to the implementation
14:27	mibu	I started solving problems in projecteuler yesterday with clojure and discovered how powerful for is. it's almost like cheating.
14:27	chrisn	I had a buddy working through that in factor
14:27	kotarak	mibu: there is also clojure-euler.wikispaces.com
14:27	chrisn	Have you taken a look at the haskell solutions?
14:28	mibu	kotarak: it's really bad you told me about this. now I might look there ;-)
14:28	kotarak	mibu: share your solutions. :)
14:29	kotarak	mibu: but be warned! SPOILER!
14:29	mibu	kotarak: I will
14:31	vogelrn	heh, what do you think, is using primes from clojure.contrib.lazy-seqs cheating? :P
14:31	mibu	vogelrn: there is primes in contrib?
14:31	vogelrn	yeah, and fib
14:32	vogelrn	considering one of the problems is
14:32	vogelrn	get the 10001st prime or something
14:32	mibu	crap, I did not know that.
14:32	mibu	I consider whatever comes with the standard language is fair game. contrib is pretty much standard, isn't it?
14:32	mibu	but writing primes or fib is not hard and even fun.
14:33	vogelrn	yeah I mean I was half-joking, both prime and fib are pretty easy to write
14:33	vogelrn	it's just that the whole point of certain problems is to write fib and primes, heh
14:33	danlarkin	there's a nice example of fib using a memoize function and atoms
14:34	danlarkin	here it is, http://clojure.org/atoms
14:35	mibu	memoize is part of the core now, right?
14:40	vogelrn	looks like it
14:43	kabny	I'm doing a GUI app that will play mp3s and sometimes at the same time update a database or take input in a textfield from the user. should I use agents then? since it is asynchronous.
14:44	kabny	why is fib and prime in seq-utils or lazy-seqs and not in math?
14:45	kabny	isnt there some java lib like numerical java that has fib and prime anyway?
14:45	vogelrn	possibly, but not lazily
14:47	vogelrn	and I don't think there's one built into java, it might be 3rd party (could be wrong though)
15:16	eldok	the more clojure I code the more I like it.
15:16	kotarak	:)
15:17	chrisn	mibu: did you check out lazy-seq permutations?
15:17	chrisn	It isn't exactly what you want, but I would start from there.
15:18	chrisn	much better than what I wrote.
15:29	kabny	is an undergraduate 4 years, then waht is graduate? how long have you actually been to uni when you have a PhD? 10years!!!!!!!!!!!!???????????
15:30	Hun	depends.
15:33	kabny	anyone use contrib/sql? how do I create a db? (sql/with-connection db) ?
15:33	kabny	after havin done:
15:33	kabny	(require '[clojure.contrib.sql :as sql])
15:33	kabny	(def db {:classname "org.apache.derby.jdbc.EmbeddedDriver"
15:33	kabny	:subprotocol "derby"
15:33	kabny	:subname "C:/clojure/progs/pod/podcasts.db"
15:33	kabny	:create true})
15:33	kabny	then the with-connection call returns nil. ok so how do I refer to it later?
15:36	Chousuke	kabny: with-connection doesn't make a connection; it creates a context. You're supposed to put your code inside the with-connection call.
15:39	Chousuke	kabny: according to the docs, your database will be accessible in the db var within the with-connection call
15:41	kabny	where are the docs?
15:41	Chousuke	er, source :)
15:42	kabny	ah because lisp code is its own documentation :)
15:43	Chousuke	(doc with-connection) may be useful
15:43	clojurebot	Excuse me?
15:45	Chousuke	kabny: apparently though you're not supposed to care about the existence of db
15:46	kabny	but what does that mean within the with-connection call?
15:46	kabny	so I should do (with-connection db-spec action) ? where action could be the create-table function?
15:46	Chousuke	yeah
15:47	Chousuke	like with-open
15:48	Chousuke	(with-open [file (open-file)] (do-something file) (do-something-else file))
15:48	Chousuke	with- is a naming convention for macros like that.
15:50	kabny	ok thanks
16:08	kabny	:subname "/tmp/clojure.contrib.sql.test.db"
16:08	kabny	is that where the db will be stored?
16:08	kabny	and how do I specify a name for the db?
16:09	kabny	scgilardi, is he the same name here?
16:09	kabny	did tom hickey maintain JScheme before after Norvig?
16:14	rhickey	kabny: no, Tim Hickey, not related
16:15	kabny	ok
16:31	kabny	god I just keep loving clojure more and more
16:32	kabny	the contrib sql is so easy to use once i got it(which didnt take to long)! so small yet so more pleasant than working directly with jdbc.
16:39	kabny	is there any plans for a html-parsing-library? basically I need to extract some stuff from a big amount of html-pages, I resort to Java then? any wish for a clojure-html-parsing-lib?
16:39	kotarak	kabny: there is some xml stuff in clojure and contrib. Maybe this helps?
16:50	chrisn	An interesting problem would be an API that is more difficult that jdbc
16:50	chrisn	odbc I guess
17:08	kabny	how do you host a webapp? I know Google appengine lets you host for free but then you have to use Python(which is fine btw). Is it good? What are the alternatives? are their good ones that let you pay a monthly fee? or is the normal thing to have your own server?
17:10	lauri	kabny:you can read about one possibility here: http://ericlavigne.wordpress.com/2008/12/18/compojure-on-a-slicehost-vps/
17:15	danlarkin	javascript snowflakes
17:15	danlarkin	what year is it?
17:16	ericlavigne	danlarkin: They'll be gone in a few days. Just celebrating Christmas :-)
17:16	danlarkin	they are distracting my eyes :(
17:17	ericlavigne	Okay, I'll turn off the snowflakes.
17:17	danlarkin	huzzah!
17:17	kotarak	ericlavigne: maybe they can be restricted to the area without text?
17:19	ericlavigne	kotarak: That would be a huge improvement, but I didn't create the theme.
17:19	ericlavigne	There's also a new article on setting up PostgreSQL for use with Clojure.
17:20	ericlavigne	http://ericlavigne.wordpress.com/2008/12/28/using-postgresql-with-compojure/
17:27	kabny	thanks eric, very cool
17:28	darkdescendant	Got a question on Java UI: How can I clear out all my Java UI within clojure without taking down clojure itself? I.e. if I create a JFrame and show it, how do I destroy it cleanly?
17:29	ericlavigne	kabny: You're welcome. I wanted to write a Compojure application anyway, and seeing that others are enjoying the articles really helps my motivation.
17:30	darkdescendant	Is it as simple as (def <my frame> nil)?
17:31	ericlavigne	darkdescendant: There is a "dispose" method on JFrame.
17:33	ericlavigne	You can also setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE) so it will dispose itself when a user hits the close button or the X.
17:33	darkdescendant	Thanx!
17:35	darkdescendant	(My Java/Swin exp is poor at best)
17:35	ericlavigne	darkdescendant: I would prefer to have less Java/Swing experience. I program Java by day and escape to Lisp at night.
17:36	kotarak	ericlavigne: sneak in a clojure.jar. ;)
17:37	ericlavigne	kotarak: The thought has crossed my mind, but my boss wants the code to be all Java because Java programmers are easier to hire.
17:38	ericlavigne	He apparently hasn't noticed how often you end up with Lisp and Haskell programmers when you look for Java programmers.
17:38	darkdescendant	I program C/C++ by day. :-)
17:38	ericlavigne	darkdescendant: Now I feel better :-P
17:38	kotarak	I "program" Excel. At least it's functional...
17:39	darkdescendant	Hey, at least basing it on Java means I can create an x-plat UI for my app. It also means I can pick my OS platform (to an extent). I have a Macbook and I run Linux and Windows under VMWare. I can easily do clojure an any of those (and in fact I setup my Linux box with it).
17:39	darkdescendant	kotarak: I feel your pain. -)
17:42	kotarak	darkdescendant: Oh. Not necessary painful. Excel is actually quite powerful. And it simply awesome for exploratory data analysis, eg. with pivot tables. But maintaining a spreadsheet with some calculations.... ugh
17:42	Chousuke	there was one guy who did a 3d cube in excel
17:43	Chousuke	I though that was the epitome of pointlessness.
17:43	Chousuke	thought*
17:43	darkdescendant	Space Invaders in Excel.
17:43	darkdescendant	I heard someone make the point that as soon as you can write a game on something, it ceases being an app and becomes an OS.
17:44	Chousuke	:p
17:57	chrisn	there is/was a weird flight simulator in excel
17:57	chrisn	It was written in c though
18:10	chrisn	given a sequence like ((1 2) (1 3) (1 4)) how do I lazily create (1 2 1 3 1 4)?
18:10	chrisn	(apply concat seq) isn't very lazy
18:10	chrisn	I don't think
18:10	ericlavigne	chrisn: I think there's a function called flatten.
18:10	ericlavigne	,(flatten '((1 2) (1 3) (1 4)))
18:10	clojurebot	java.lang.Exception: Unable to resolve symbol: flatten in this context (NO_SOURCE_FILE:0)
18:11	kotarak	(interpose (ffirst s) (map second s))
18:11	ericlavigne	maybe flatten is in clojure-contrib
18:12	danlarkin	it is, in seq-utils I believe
18:13	chrisn	found it, thanks
18:14	chrisn	It appears to do a complete flatten using tree-seq, but only return items that aren't sequences
18:18	Chousuke	hm
18:18	kabny	javadoc in contrib, is it for auto-generating documentation of clojure-files?
18:18	Chousuke	I'm experimenting with my own clojurebot
18:18	kabny	we need such a program...
18:18	Chousuke	and it's not letting me run any code...
18:18	Chousuke	I wonder what's wrong.
18:19	Chousuke	it keeps complaining about classloaders
18:19	Chousuke	,(System/getProperty "java.home")
18:19	clojurebot	java.security.AccessControlException: access denied (java.util.PropertyPermission java.home read) (NO_SOURCE_FILE:0)
18:19	Chousuke	hmm
18:20	Chousuke	so it should allow some stuff.
18:22	Chousuke	... my policy file is somehow screwed up I guess
18:23	Chousuke	it's a simple grant-all file though
18:34	kabny	anyone use tagsoup? i cant find the documentation: http://home.ccil.org/~cowan/XML/tagsoup/#warning
18:34	kabny	is htmlparser good?
18:45	kabny	htmlparser seems good
18:46	ericlavigne	kabny: what are you working on?
18:47	kabny	recommender/aggregator thingie
18:47	kabny	webapp/cellphone app
18:47	kabny	gonna do for android in Java and the webapp in Clojure+compojure
19:22	kabny	what does protected constructor mean? god some Java-libs are so deeply nested(but better too much documentation that none at all I guess).
19:24	gnuvince_	What's a good intro book on Java without the usual "a variable is a memory cell where you can put a value" newbie stuff?
19:25	drewr	gnuvince_: I thought "Thinking In Java" was OK, but it does have its share of newbie-friendly stuff.
19:27	emacsen	So the DC Clojure study group is still looking for project ideas if anyone has any. Something generally useful but not full time projects
19:30	kabny	if: (URL. site) works then why doesnt: (HttpURLConnection. (URL. site))
19:30	kabny	java.lang.IllegalArgumentException: No matching ctor found
19:30	kabny	when
19:30	kabny	protected HttpURLConnection(URL u)
19:30	kabny	Constructor for the HttpURLConnection.
19:30	kabny	http://java.sun.com/j2se/1.4.2/docs/api/java/net/HttpURLConnection.html
19:31	rhickey	kabny: it's protected
19:32	danlarkin	kabny: there's an openConnection method on URL I think?
20:37	kabny	<i><a href="http://media.libsyn.com/media/seradio/seradio-episode119-DSLsInPracticeWithJPTolvanen.mp3" rel="nofollow">Download MP3</a></i>
20:37	kabny	what does nofollow mean? dont link?
20:38	kabny	or wait it is for googles spider
20:40	Chouser	kabny: it's meant for google and other spiders to indicate no enorsement of the quality of the link
20:52	kabny	why doesnt (doc multimethods return the args passed)?
20:58	Chouser	kabny: by default defmulti doesn't add arglist or doc metadata
20:58	Chouser	but you can provide either or both:
20:58	Chouser	(defmulti #^{:doc "does foo stuff" :arglists '([bar & more])} foo class)
20:59	kabny	how can I convert a string to a regexp?
21:00	kabny	"mp3" to #"mp3"
21:00	Chouser	(doc re-pattern)
21:00	clojurebot	Returns an instance of java.util.regex.Pattern, for use, e.g. in re-matcher.; arglists ([s])
21:09	eldok	i added the metadata but it still doesnt show up when doing (doc f)
21:09	eldok	whats the char I have to add when asking for metadata nyway?
21:12	eldok	(defn scanl
21:12	eldok	#^{:doc
21:12	eldok	that is the correct place for meta right?
21:13	Chouser	eldok: not like that. you can put a plain string there instead #^{...} and it'll work.
21:14	alphazero	gnuvince_: http://www.mindview.net/Books/TIJ/
21:14	Chouser	eldok: or just leave off the #^ prefix
21:15	Chouser	eldok: those are features of 'defn'. To use the more general #^{...} format, put that before the name of the var you're defining.
21:16	Chouser	kabny, eldok: http://paste.lisp.org/display/72759
22:39	achim_p	hi all! is anybody aware of a bytecode inspection/disassembly tool that doesn't choke on clojure bytecode?
22:40	achim_p	i just tried to package a clj hello world for android, which gave me a bytecode related error
22:42	achim_p	http://pastie.org/348098 - now i'd like to see what's happening at bytecode offset 0000003a ...
22:48	eldok	achim_p: sorry I can't help you but really cool you try to get Clojure going n Android. I'm writing a webapp/Android app using Clojure/Java. Would really like to write everything in Clojure.
22:49	eldok	achim_p: since you are doing such stuff I suppose you are aware that Android use its own VM, the Dalvik VM. could that be related to the error?
22:51	achim_p	eldok: it doesn't even get that far, it fails while building. the "dexer" doesn't seem to like ns_public's bytecode
22:54	eldok	dexer?
22:55	eldok	are you running it on a real phone or on the emulator?
23:02	achim_p	eldok: dx, the tool that generates dex files. i'm on an emulator, but i don't think that's emulator-specific ... i don't know much about android though
23:02	achim_p	http://code.google.com/intl/de-DE/android/reference/othertools.html
23:08	eldok	so you use Clojure's compile then dx to convert to Android bytecode?
23:09	achim_p	yep
23:11	eldok	so probably it is the clojure-generated code that is incompatible with Dalvik bytecode?
23:11	achim_p	so it seems
23:11	eldok	rhickey: where is compile?
23:13	danlarkin	IIRC there is a vestigial class loader related issue with the android VM
23:13	eldok	vestigial?
23:13	danlarkin	that may have been dealt with by now, though
23:14	danlarkin	I'm often wrong about these things I pull from the back of my brain
23:14	eldok	A rudimentary or degenerate, usually nonfunctioning, structure that is the remnant of an organ or part that was fully developed or functioning in a preceding generation or an earlier stage of development.
23:15	achim_p	that's the error message: local variable type mismatch: attempt to set or access a value of type java.lang.Object using a local variable of type boolean. This is symptomatic of .class transformation tools that ignore local variable information.
23:15	achim_p	doesn't look classloader-related
23:16	danlarkin	I was going for the, "having become functionless in the course of evolution"
23:17	rhickey	I saw this when I first tried dx from the Android SDK - looking at it now. It is a bytecode thing, not related to classloaders - the dx verifier chokes on something the Java verifier doesn't
23:17	danlarkin	wrong again! my record continues
23:21	gnuvince	I asked a question earlier today, but I've been having problems with my Internet connection all day since then, so I haven't caught an answer (if there were one): what book would you suggest to somebody who wants to quickly get up to speed on Java?
23:22	zakwilson	http://per.bothner.com/blog/2008/AndroidHelloScheme/ <-- somebody just got Kawa working on Android.
23:22	eldok	(defn hash
23:22	eldok	"Returns the hash code of its argument"
23:22	eldok	[x] (. clojure.lang.Util (hash x)))
23:23	eldok	can someone explain that to me?
23:23	eldok	rhickey: where is compile in the src of Clojure?
23:23	gnuvince	eldok: this calls the .hash() method of clojure.lang.Util with an argument x.
23:24	rhickey	eldok: clojure.lang.Compiler
23:26	eldok	ah so it refers to another method hash
23:29	eldok	hmm so it is not the compile.java but the:
23:29	eldok	public static Object compile(Reader rdr, String sourcePath, String sourceName) throws Exception{
23:29	eldok	in Compiler.java ?