#clojure – 2008-06-18

2008-06-18

01:36	jcrites	when I get further along in my Clojure development and I would, in another language, keep a file rather than interactive in the REPL, how would I do this?
01:36	jcrites	do I execute Java on the clojure jar with a different class?
01:36	jcrites	how do I run a clojure "program" normally? (i.e., non-repl)
01:39	abrooks	jcrites: The Clojure wiki provides script wrappers to call java with your .clj files.
01:40	abrooks	jcrites: The wiki is here, BTW: http://en.wikibooks.org/wiki/Clojure_Programming
01:40	jcrites	wikibooks eh?
01:41	jcrites	thanks for the reference
01:41	jcrites	now I can start using Clojure in production at my work ;-)
01:41	abrooks	Not so much of a book at this point... :)
01:41	jcrites	is there any way to turn Clojure into a jar?
01:41	jcrites	it would be really nice to have a jar I can just pass around in the usual places
01:42	jcrites	perhaps the jar just runs clj files stored inside of it, but it would still be convenient
01:42	abrooks	I think there was some discussion of that in the Clojure Google Group and possibly here.
01:42	jcrites	hmmm, maybe I should make it?
01:42	abrooks	You can place .clj files into the jar, I know.
01:42	abrooks	Compiling .clj to class files in the .jar, I
01:43	jcrites	I just meant to say that I recognize it doesn't necessarily need to be "compiled", just packaged up for execution
01:43	abrooks	Compiling .clj to class files in the .jar, I'm not so sure.
01:43	jcrites	yeah :)
01:43	abrooks	I suspect it's possible.
01:43	abrooks	I suspect also that I should be in bed -- goodnight!
01:44	jcrites	good night
11:40	jteo	hmm?
11:41	Chouser	On google group, creating a namespace the same as a class name. Redefining Math/PI to 3.14
13:58	abrooks	Chouser: Hehe.
13:59	abrooks	Chouser: Shouldn't PI be defined as 3 in compliance with the state of Indiana? :)
14:00	Lau_of_DK	haha, state of India?
14:01	abrooks	Ah, no this is semi-apocryphal: http://en.wikipedia.org/wiki/Indiana_Pi_Bill
14:01	Lau_of_DK	wow, thats really messed up
14:01	abrooks	Lau_of_DK: Heh. No, Indiana, USA, in the midwest.
14:12	Chouser	But yes, messed up.
14:19	Lau_of_DK	Evening Chouser
14:24	Lau_of_DK	Gents, Am I wrong in expecting that adding a PropertyChangeListener to either my main panel or JFrame would fire an event when the window is resized?
14:35	Lau_of_DK	Yes I am
15:05	Chouser	Lau_of_DK: hello!
15:08	Lau_of_DK	:)
15:09	Chouser	sorry, a little slow today.
15:11	Lau_of_DK	its fine - I dont know your circumstances, but I usually only hit IRC after a looong days work :)
15:11	Lau_of_DK	(so - I default to slow)
15:58	Lau_of_DK	Where is (exp base power) hidden in Clojure?
15:59	Chouser	Probably not in Clojure at all. try java.lang.Math?
15:59	Lau_of_DK	seems odd to leave it out imo
16:00	Chouser	Clojure has only a few Math primitives, since the Math class is right there.
16:00	Lau_of_DK	I'm still at the ewww Java stage though :)
16:01	Chouser	(Math/pow 2 10) => 1024.0
16:04	Chouser	Anyone here want to help me write some really high-quality Java code so that when I blow it away with equivalent Clojure it's not just a straw-man argument?
16:04	Leafw	Chouser : what kind of code
16:05	Leafw	Lau_of_DK : try pow
16:05	Lau_of_DK	Yea thanks Leafw and Chouser , I got it
16:05	Chouser	I'm thinking maybe a function that takes two lists (or arrays or whatever) and produces a new one that is the sum of each pair.
16:05	Leafw	Lau_of_DK : oops, confused ... pow is not there.
16:06	Leafw	Chouser : lists of primitives?
16:06	Chouser	in clojure, a foo where (foo [1 2 3] [4 5 6]) => [5 7 9]
16:06	Chouser	sure.
16:06	Chouser	ints
16:06	Lau_of_DK	(. Math pow 2 2) = 4.0
16:06	Chouser	or Integers, whatever.
16:06	Leafw	it's not the same :)
16:07	Chouser	I know, but I'm not looking for perfect equivalence with Clojure, I just want code that won't make a Java programmer laugh
16:07	Leafw	I wrote some benchmarks
16:07	Chouser	I don't want them to say, "well sure your Clojure code looks better, but who would right Java like that?"
16:07	Leafw	that made Rich add all the primitive array support
16:07	Chouser	hm, yeah, I should look at those.
16:09	Leafw	I can post them ... http://git.pastebin.com/m8a0c849
16:10	Leafw	it's a very simple sum.
16:10	Leafw	I am actually using Clojure for imae processing, doing haar transforms, gaussian filtering, and minor things
16:10	Leafw	some examples: http://pacific.mpi-cbg.de/wiki/index.php/Clojure_Scripting
16:11	Leafw	another: http://pacific.mpi-cbg.de/wiki/index.php/Scripting_comparisons
16:11	Chouser	i think I've looked at those pages before. :-)
16:11	Leafw	the last one compares code from java., jython, javascript, jruby and clojure (two versions: one mine, naive, one from Rich)
16:11	Leafw	:)
16:11	Chouser	I guess I'm looking more to compare expressiveness rather than performance.
16:12	Leafw	then do a real-world example
16:12	Leafw	like: can you fix my example here: http://pacific.mpi-cbg.de/wiki/index.php/Clojure_Scripting#Fixing_overexposed_images:_setting_a_pixel_value_to_a_desirable_one_for_all_overexposed_pixels
16:12	Leafw	can this be done easier?
16:13	Leafw	the problem: some pixels have a value of zero, erroneously. They need to be set to a specific value. So "set all pixels with value zero to X"
16:14	Leafw	ideally, with native performance ,and ideally, for all byte, short and float pixel arrays.
16:14	Leafw	in java this is a loop, but one needs a class declaration and all that noise.
16:14	Chouser	Maybe I'm not saying this right: I want some Java source code to do the task I described above.
16:15	Chouser	Maybe I'll just write something and post it for people to critisize and/or fix.
16:15	Leafw	xD
16:15	Leafw	I was trying to move you into my own example ... I'll write it for you
16:16	Leafw	same length, or unequqla length of the lists ?
16:17	Chouser	equal length
16:18	Chouser	are arrays the Right Thing to use in Java, or something else?
16:18	Leafw	http://git.pastebin.com/d75b6d2dd
16:18	Chouser	ok, perfect!
16:18	Chouser	thanks!
16:18	Leafw	that depends on what you want to do (and that is the problem: one needs to rewrite the functin for int, short, long, float, double, byte ... or Object Integer, Float, Byte, etc.)
16:19	Chouser	ok, no, this is fine.
16:19	Leafw	well: in clojure, one does not need to rewrite the function, which is great.
16:19	Chouser	this demonstrates clumsy iteration, extra variables (i, len), and mutable data.
16:20	Chouser	and of course the clojure equivalent is (map + list1 list2)
16:22	Leafw	I knew that :)
16:23	Leafw	clojure finally lets one live in the JVM without the hassle of java.
16:23	Leafw	the clojure equivalent is (let [s (map + list1 list)] ... )
16:24	Leafw	or list3 == s
16:27	rhickey_	Chouser: prepping for your talk?
16:28	Chouser	rhickey_: yessir
16:29	Chouser	I'm going to try a somewhat different angle than your talk, even though I expect the audience to be pretty much the same.
16:30	rhickey_	how much time do you have?
16:30	Chouser	But I only have 1 hour at most, and your talk is already out there if they want it.
16:31	Chouser	so I'm going to try less of a ground-up description of Lisp. Just some basics and then straight into comparisons and examples.
16:32	drewr	Chouser: To whom are you speaking?
16:32	Chouser	I guess there's only going to be about 8 people there, so if I turn them off completely to Clojure it's still not too much damage.
16:33	Leafw	Chouser : "there" being where?
16:33	Chouser	some kind of lunchtime tech-talk group at my friend's workplace. Outside Chicago.
16:33	Leafw	ok
16:35	Chouser	rhickey_: I plan to send you my slides so you can critque them (if you want to -- no obligation!)
16:36	Chouser	the first few should be very familiar
16:39	rhickey_	ok
16:40	drewr	Why does "\p{Space}+
16:40	drewr	" give me "Unsupported escape character: \p" ?
16:40	drewr	When used as a java.util.regex.Pattern.
16:41	Chouser	#"\\p"
16:41	rsynnott	in general, the rule is to add more slashes until it works, with this sort of thing
16:41	Chouser	you have to escape your \ to get it past the string parser and into the regex parser
16:41	rsynnott	(I've seen up to four for regexes :) )
16:41	Chouser	which is icky (and exactly like Java and elisp)
16:41	drewr	I guess I've been spoiled by Python's r'' syntax.
16:42	rhickey_	I'm amenable to thinning out the \s but the regex wizards ran aground somewhere in trying to spec that
16:43	Chouser	A solution has been discussed.
16:43	Chouser	Somewhere in here: http://groups.google.com/group/clojure/browse_thread/thread/81b361a4e82602b7/234122dfe281744f
16:45	drewr	Does this [Ljava.lang.String;@51c2b4 mean that I got back an array of Strings?
16:45	rhickey_	drewr: yup
16:48	drewr	Ah, SEQ and VEC work on it.
16:50	Chouser	aw, amap doesn't take multiple arrays.
16:50	Chouser	such a pity!
16:50	rhickey_	does it need multiples?
16:50	rhickey_	just needs the driving array
16:50	rhickey_	expression can refer to others
16:55	Chouser	no, it certainly doesn't need it.
16:59	rhickey_	so, it's ok or you still want multiple arrays?
17:09	Chouser	amap doesn't do an aget on the primary array, right? So no, there's no benefit (that i can think of) for multiple arrays.
17:10	Chouser	oh. he's gone.
17:11	abrooks	Chouser: When's your Chicago Clojure talk?
17:11	Chouser	Friday
17:11	abrooks	How's it going? Is there anything for me to help with?
17:12	Chouser	It's going fine, I think.
17:38	drewr	What's the best way to mimic BOUNDP?
17:38	drewr	I want to see if a Var already exists.
17:41	Chouser	the logs say (.isBound #'rest) but that doesn't work for me
17:42	drewr	Me neither.
17:44	Chouser	I got that from: http://clojure-log.n01se.net/date/2008-05-27.html#07:54
17:44	Chouser	(var 'foo) gives a strange error
17:46	Chouser	drewr: this is a namespaced global var?
17:46	drewr	Yes.
17:46	drewr	It's a jdbc connection, e.g., conn, that I want to memoize.
17:46	drewr	I only need one of them.
17:47	Chouser	(contains? (ns-map (find-ns 'user)) 'foo)
17:48	shizzy0	hello
17:48	drewr	Chouser: Nice, that works.
17:48	Chouser	oh, drop the contains? ((ns-map (find-ns 'user)) 'foo)
17:48	Chouser	shizzy0: hi!
17:48	shizzy0	I have a question. How is the :test and (test) function supposed to work?
17:50	shizzy0	I'm looking at the definition of (test [v]) in boot.clj, and am I right to think, that it's supposed to work like this: (test +) will run a test on the + function if it has a test. Is that how it's supposed to work?
17:51	Chouser	apparently, yes. I've not used it.
17:53	shizzy0	[nods] cool. that's interesting, so in the :test you actually put a function.
17:54	Chouser	yes. I'm currently failing in my attempts to do so, but that's what the docs and code seem to do.
17:55	shizzy0	I don't see it being exercised anywhere, but as I'm trying to get my head around how to work with clojure, it makes sense to do it in a unit-testy way. I guess, that's just how I do my discovery programming now.
18:00	Chouser	huh, it looks like test will only call :test with no parameters
18:00	shizzy0	Thanks, Chouser. Looks like this works: (defn #^{ :test (fn [] (assert (= 1 (test-test)))) }
18:00	shizzy0	test-test []
18:00	shizzy0	1)
18:00	shizzy0	exercising it with: (test #'test-test)
18:01	shizzy0	no parameters is kind of typical with unit testing.
18:01	Chouser	oh, ok.
18:01	Chouser	ah, assert is nice.
18:02	shizzy0	[nods] yeah. It's great that you can get the actual expression that was tested. I love macros.
18:02	Chouser	you can also say: (defn test-test {:test #(assert (= 1 (test-test)))} [] 1)
18:03	shizzy0	oh good. That's a nicer way of expressing it.
18:04	shizzy0	Is there a way that one could do it so, I could do it like this (deftest my-function ...) that would add it to the meta of an already defined "my-function"?
18:04	Chouser	sure
18:04	shizzy0	cool. I'm going to try that.
18:05	Chouser	I need to go, but you'll need to use with-meta
18:05	shizzy0	[nods] awesome. I'll check it out.
18:05	shizzy0	Good chatting with you, Chouser.
18:05	Chouser	and if deftest's first arg is meant to be unquoted like that, deftest will have to be a macro
18:13	shizzy0	Hello rhickey, I'm playing around with (test v) and :test. Do you have any ideas about it you'd like to me about it? It looks like it's currently a way to attach a parameterless unit test to any given function.
18:15	rhickey	shizzy0: I don't have any coherent plan yet, only a preference that tests produce result data rather than print
18:18	drewr	Chouser: I just noticed that FIND-VAR does what I wanted. :-)
18:18	shizzy0	rhickey: [nods] that's cool. Is that to encourage people to write tests rather than print, read, and interpret results?
18:23	shizzy0	rhickey: I'm trying to define a deftest macro. Is it possible to define the function and the test separately, e.g. (deftest assoc [] ...)?
18:30	cgrand	shizzy0: look at the source for defmethod for a way to alter an existing function
18:31	rhickey	there's no rule that says the test must go on the var metadata, you could have a test suite in a map keyed by var, for instance
18:32	shizzy0	cgrand: thanks for the hint. :)
18:34	shizzy0	rhickey: [nods] I was thinking about just doing a simple general unit test suite. No frills, but something that would work. I really like the meta data, and how I can just grab all the functions I'm interested in (say those tagged with :unit-test) and run them.
20:13	Chouser	drewr: ah, cool.
20:14	dudleyf	reload /style
20:14	Chouser	swing and a miss
20:28	slava	rhickey: is there a reference describing persistent vectors somewhere?
20:29	slava	rhickey: i find the code a bit hard to follow, with the 'Box' thing
20:29	slava	rhickey: i just noticed my implementation of pop was wrong, but i don't really undersatnd how its supposed to work :)
20:31	rhickey	yeah, the box is working around lack of multiple returns
20:32	slava	the part that confuses me is that the box is passed around during recursive calls to popTail(), and it gets mutated
20:32	slava	it would be more clear if there was a new box every time
20:32	rhickey	The persistent arrays are an persistent implementation of Bagwell's hash tries: http://lampwww.epfl.ch/papers/idealhashtrees.pdf
20:33	rhickey	yes, but new box each time would be slower
21:08	Chouser	rhickey: when someone says Clojure doesn't have cons cells, wouldn't argue that's essentially what PersistentList is?
21:17	rhickey	Chouser: yes
21:18	rhickey	even more so, clojure.lang.Cons
21:18	rhickey	what it doesn't have is cons cells as arbitrary pairs
21:20	Chouser	Heh, I didn't know about Cons
21:20	Chouser	Is (clojure.lang.Cons. 1 nil) the only way to make one?
21:22	rhickey	when you cons onto a seq, you get a Cons, except if that seq was a PersistentList already
21:23	rhickey	see ASeq.cons
21:29	Chouser	ah, ok
23:25	yrb	is there way to new up nested classes other than using the name of the actual class file eg. Ellipse2D$Float
23:58	dudleyf	reload /style