#clojure – 2009-07-17

2009-07-17

00:55	skalnik	how do I check if a sequence is empty?
00:55	grrrt	empty?
00:55	grrrt	,(doc empty?)
00:55	clojurebot	"([coll]); Returns true if coll has no items - same as (not (seq coll)). Please use the idiom (seq x) rather than (not (empty? x))"
00:56	skalnik	thanks :)
00:56	grrrt	I find this website quite useful at times: http://java.ociweb.com/mark/clojure/ClojureCategorized.html
00:56	grrrt	it has all (most?) clojure functions by category
00:57	skalnik	nice
00:57	grrrt	useful if you're looking for something without knowing the exact name
01:01	skalnik	yay, coded euler problem 3 :)
01:04	grrrt	metadata still has me confused. I wish I could do this:
01:04	grrrt	,(def t (ref 0))
01:04	clojurebot	DENIED
01:04	grrrt	oh allright
01:05	hiredman	erm
01:05	grrrt	I wish I could do this: (def t (ref 0)) (with-meta t {:foo "bar"})
01:05	durka42	(let [t (ref 0)] (with-meta t {:foo "bar"}))
01:05	durka42	,(let [t (ref 0)] (with-meta t {:foo "bar"}))
01:05	clojurebot	java.lang.ClassCastException: clojure.lang.Ref cannot be cast to clojure.lang.IObj
01:05	grrrt	exactly
01:05	grrrt	clearly I'm missing something
01:06	hiredman	,(let [t (ref 0)] (alter-meta t assoc :foo "bar"))
01:06	clojurebot	java.lang.Exception: Unable to resolve symbol: alter-meta in this context
01:06	hiredman	,(let [t (ref 0)] (alter-meta! t assoc :foo "bar"))
01:06	clojurebot	{:foo "bar"}
01:06	hiredman	,(let [t (ref 0)] ^(alter-meta! t assoc :foo "bar"))
01:06	clojurebot	nil
01:06	hiredman	bah
01:06	grrrt	heh
01:06	hiredman	,(let [t (ref 0)] (alter-meta! t assoc :foo "bar") ^t)
01:06	clojurebot	{:foo "bar"}
01:06	durka42	,(let [t (ref 0)] (alter-meta! t assoc :foo "bar") t)
01:06	clojurebot	#<Ref@bdc53e: 0>
01:06	grrrt	right. So why does with-meta not work then?
01:07	hiredman	there are several meta data related interfaces
01:07	durka42	that seems like a huge bug
01:07	hiredman	with-meta effectively returns a new object with the given metadata
01:07	hiredman	which is not what you want in this case
01:07	grrrt	hmm, I can see that being problematic for refs
01:07	grrrt	yeah
01:07	grrrt	point taken
01:08	grrrt	thx hiredman ! #clojure rocks.
01:20	skalnik	hm, how do I turn a character list into a string?
01:20	grrrt	,(str \a \b)
01:20	clojurebot	"ab"
01:21	grrrt	,(apply str [\a \b])
01:21	clojurebot	"ab"
01:21	skalnik	hmm
01:21	skalnik	thanks
01:21	skalnik	yeah, apply str worked
01:21	skalnik	makes sense.
01:51	grrrt	weird... back in my java days I would work on a project, writing code, code and more code. Eventually I would sit back and look at the large amount of code I had written and I'd feel pretty impressed with myself.
01:51	grrrt	With clojure, I write code and more code, but then when I sit back I think "hey is that all?"
01:51	grrrt	Clojure is just so much more expressive...
01:51	mariorz	its all the lisp
01:53	mariorz	i think you work at ibm you get bonuses by kloc's though
01:53	grrrt	In my last java job we had the rule "no methods with more than 15 lines"... In clojure I don't even have to try to stay under 15 :)
01:53	mariorz	if you*
01:53	mariorz	:P
04:49	gko	,1
04:49	clojurebot	1
04:49	cp2	,42
04:49	clojurebot	42
04:49	jdz_	strange, ain't it?
05:02	cp2	very
05:19	gko	Any user of clojure-dev (for Eclipse?)
05:19	gko	Any user of clojure-dev (for Eclipse) ?
05:45	Fossi	hi. is there a pattern/helper for catching exceptions in lazy seqs?
06:17	cark	Fossi : you may (doall your-sequence) and souround this with a try form
06:56	Fossi	cark: that's what i figured. now i just need to find out why it's still not being catched. :)
06:57	Fossi	it's still a little arkward if your data is not a simple sequence, but a nested structure
06:57	cark	maybe your sequence contains other lazy saquences ?
06:57	Fossi	that's what i suspect
06:57	Fossi	so a structure-walking helper would be helpful
06:58	cark	is this only for debugging ? or do you want this for production as well ?
06:58	Fossi	i try to make compojure not throw exceptions to the frontend
06:58	cark	a quick way to make your sequence concrete is to pprint it
06:59	Fossi	well, that is a code walker :)
06:59	Fossi	or data walker in that case
06:59	cark	right =)
07:00	Fossi	should be a pretty common use-case with web applications. maybe something i can give back upstream later
07:00	cark	well usually with compojure you'll build vectors instead of sequences, and these are not lazy
07:01	Fossi	hmmm
07:01	Fossi	maybe somethings wrong then on some other end
07:01	cark	also it's no big deal if your exceptions fires later, you may change the error page i think
07:02	Fossi	i searched a while in the docs and also code, but i could point anything like that
07:02	Fossi	*couldn't
07:03	cark	mhh
07:03	cark	there must be !
07:03	cark	=P
07:03	Fossi	in fact i greped for "try" and there wasn't any in the code
07:03	cark	my guess is that the web server library has the try
07:04	Fossi	might be, but since we run it on different once, that's not helping so much
07:04	Fossi	*ones
07:04	Fossi	no english skills today ;)
07:05	Fossi	the error-pages look different on tomcat/jetty etc, so it looks like the exception just falls through to the container
07:06	cark	well then talk directly to jetty
07:06	Fossi	as said: because we run on different containers, that's not really a nice solution.
07:06	Fossi	i'll decorating my app with some exception handling somehow
07:07	Fossi	but first i need to somehow catch any exception
07:07	cark	then you'r bound to walk the data structures
07:07	Fossi	yeah, i guess so
07:07	cark	though you know, it's a feature in composure to be able to work with lazy sequences
07:08	Fossi	yeah, especially for streaming a doall you be real bad (tm)
07:08	cark	i remember reading a post on the google group about using this feature to update a page
07:08	cark	ahwell you can't have the cake and eat it too =)
07:09	Fossi	i'll put the issue aside for a while and fix the cause of the exceptions first. should be easy to provoke later on.
08:41	Fossi	what's the right way to 'un-keyword' something? so make :http "http"?
08:42	Fossi	prolly (key (map-with-known-values)), but if i don't know them? str?
08:42	cark	,(name :hello)
08:42	clojurebot	"hello"
08:43	Fossi	ah, cool
08:46	Fossi	and the lisp-1 thing bites me again...
08:49	cark	how so ?
08:50	Fossi	having a variable called name in just that function
08:51	cark	ahwell you'll get used to it, i came from common lisp and got used to it
08:52	cark	i'm pretty sure that variable ought to be named customer-name anyways !
08:52	Fossi	more like server-name, but yeah
08:52	cark	=)
08:53	Chouser	heh
08:53	Fossi	it's a little weird when you don't know there's a function of that name around somewhere and rename, but miss one occurence
08:53	rhickey	"name" is actually the only name that gives me Lisp-1 problems
08:54	Fossi	still compiles, but then you get a mystical "can't cast IFn to String" or something
08:55	Chouser	I see people stumbling over others, but "name" is probably the most common.
08:57	djpowell	is print-method officially usable?
08:57	djpowell	i assume that print-method is just for creating arbitrary human-readable (?) print representations
08:58	Fossi	i've had val key and map as well
08:59	djpowell	i've got a vector with 'type' metadata, and if I override print-method for that type, then it works, but I notice that it also overrides the behaviour of print-dup - which isn't what I want, cause my print-method output isn't readable
09:02	cemerick	I believe print-dup falls back on print-method impls...
09:16	AWizzArd	Yes, cemerick is right. And one can add or overwrite those at runtime to get new printing behaviour.
09:22	djpowell	Is print-method output expected to be 'read'able? no?
09:23	djpowell	I was just worried that by providing my own, un-'read'able print-method for a meta-data 'type'd vector, it causes print-dup to use it, rather than to use the more suitable print-dup for vector.
09:25	rhickey	djpowell: readability will only matter to a reader. The only time Clojure will print-dup/read it is when the type is a constant in code
09:33	skalnik	so I have a list of 20 booleans, how do I make sure they're all true?
09:34	skalnik	nevermind :)
10:11	fsodomka	Chouser: please, don't forget about http://clojure-log.n01se.net/ -- logs are still not showing
10:11	Chouser	fsodomka: yes, thanks.
10:13	fsodomka	rhickey: I saw that in the chunks Clojure branch, you changed tests for 'range'
10:13	fsodomka	what is the correct behavior for range with fractions?
10:16	rhickey	fsodomka: it will be that it returns values as long as < n
10:17	fsodomka	so (range 2.5) is (0 1 2)
10:17	rhickey	right
10:18	rhickey	in the future
10:18	fsodomka	future feature :-)
10:18	drewr	clojure knows the future?
10:18	drewr	excellent
10:18	rhickey	drewr: clojure is the future
10:18	drewr	even better
10:19	rhickey	or merely, clojure is its own future
10:19	drewr	self-referential future == single reality
10:24	fsodomka	rhickey: would it be ok, if I write Clojure tests separately in my own branch? using patches is really hard-to-work-with solution (at least for me)
10:24	fsodomka	commits are transparent, so other people who write tests won't do the same thing/area
10:25	fsodomka	http://github.com/fsodomka/clojure/commits/testclojure
10:26	fsodomka	once in a while, we can just merge branches to get tests in
10:26	Chouser	that merge can be done via a patch
10:28	fsodomka	yeah, that would work too
10:29	rhickey	fsodomka: we're still working on a pull mechanism for contributions, but I'm not opposed for bigger things as they are pulled into clojure, like the test lib itself. I don't want it to be harder for people once their stuff gets included. OTOH, as Chouser says, if once in a while you run git format-patch it should reconcile when you resync
10:38	fsodomka	rhickey: the most important thing for me, was to be able to do check-ins. Now since I know that every check-in doesn't have to be a patch, I can work with it. I will contribute a bigger patch once in a while :-)
10:41	Chousuke	fsodomka: there's no need to squash every commit into one if you use format-patch, though.
10:42	Chousuke	fsodomka: a good way to do it is to clean up the history and commit messages, but keep every logical change as a separate commit, then dump them with git-format
10:43	Chousuke	er, format-patch :P
10:45	stuartsierra	Has anyone made progress on Clojure + OSGi?
10:46	fsodomka	Chousuke: how or what tools do you use to do this clean up? (I am new to git) Or what git functions do this clean up?
10:47	Chousuke	well, assuming you have all your commits in a separate branch, you can do an interactive rebase for example
10:47	Chousuke	it allows you to delete, reorder and squash together commits.
10:47	Chousuke	you can think of each git commit as a single patch. it's pretty much how it works.
10:48	Chousuke	for example, if you are on master, do git checkout -b my-changes; then do a few commits, and try git rebase --interactive master
10:49	Chousuke	though, as rebase rewrites history, you should not use it on branches that you have shared with others.
10:50	Chousuke	it's a good way to get rid of all those "oops" and "typo" commits that happen during development, though :)
10:50	Chouser	I wouldn't personally worry too much about cleaning up the history, esp. in test directories.
10:51	rhickey	stuartsierra: I've made a bunch of changes that should help things there, but still need someone to define what exactly that means and what the expectations are
10:51	Chousuke	Well, I have perfectionist tendencies :P
10:52	Chousuke	if all your mistakes are local, there's no harm in cleaning up before sending a patch out
10:52	Chouser	But don't squash commits together too aggressively. If you submit a big patch with lots of commits in it, and all the commits are good but there's questions on one of them, it's relatively easy to create a new patch with that one commit left out.
10:52	drewr	Chouser: +1
10:53	drewr	small commits, isolated concerns
10:53	Chouser	that way most of a batch of changes could get merged in without being held up by a queation about one of them.
10:53	Chousuke	I'm not advocating big commits. I'm against big commits. :P
10:53	stuartsierra	rhickey: thanks. I'm just thinking about modularity & dependency management in general, and OSGi seems to be the Java standard.
10:53	Chousuke	I just don't like seeing "oops" in the logs. :)
10:53	Chousuke	it makes bisecting less effective, too :/
10:53	Chouser	Chousuke: yeah, didn't mean to suggest otherwise. Just pointing out the one part of "clean history" that I think is most important.
10:54	Chousuke	small commits are also easier to revert. :)
10:55	rhickey	stuartsierra: there are 2 or 3 aspects I think - one is whether or not independently loaded Clojure code with imports of classes know only in their 'module' can work, That should be much better. The other is can modules have largely independent Clojure namespaces etc. This will require getting rid of the central ns repository. Third is exposing Clojure itself as some sort of modular 'service'
10:56	rhickey	dependency part a whole other can of worms, at least as far as incorporating Clojure ns deps
10:57	rhickey	still have yet to have anyone describe adequately what it means to 'get Clojure running under OSGi'
10:59	fsodomka	thanks for the help with git - I will read up on it and play with it a little :-)
10:59	stuartsierra	I think, ideally, one would want to be able to distribute Clojure libraries as OSGi bundles, with declared dependencies.
11:00	Chousuke	fsodomka: http://www-cs-students.stanford.edu/~blynn/gitmagic/ is a nice tutorial
11:03	stuartsierra	What I want is CPAN-style discovery with OSGi-style dependency management.
11:05	cemerick	osgi is a big, hairy pill to swallow just to get dependency mgmt (IMO of course)
11:05	stuartsierra	cemerick: agreed, but what else is there for Java libs?
11:06	cemerick	maven, ivy, jigsaw (forthcoming)
11:06	cemerick	there's other less well-known ones shrug
11:07	stuartsierra	But don't maven/ivy/etc handle only half the problem, finding & downloading dependencies?
11:07	stuartsierra	They don't do nested ClassLoaders.
11:08	cemerick	right, no, they don't do that
11:08	cemerick	jigsaw does, but it's vaporware at the moment
11:08	stuartsierra	ah, ok
11:09	cemerick	course, when JDK 7 hits, we'll have to see if it's going to play java.util.logging to osgi's log4j
11:10	stuartsierra	Hmm, yes.
11:11	cemerick	I'm infinitely distrustful of anything that claims to do anything like CPAN. There's lots of them, but none of them work half as well as the original (partially due to code-rot, partially due to other platforms not being like perl, partially due to bad impls).
11:12	stuartsierra	Yes, Rubygems, Python eggs, and Maven are all inferior to CPAN.
11:12	stuartsierra	I'm trying to figure out why.
11:13	cemerick	do let me know when you've got it :-)
11:13	cemerick	I generally just throw my hands up in frustration and go do something else productive. I can't stand to deal with stuff like that.
11:13	stuartsierra	Well, I'm supposed to talk about it for Philly Lambda on Tuesday. :)
11:13	cemerick	ah-ha. good motivation!
11:13	stuartsierra	yep
11:14	cemerick	Case in point, I've got a pylons app that I'd like to migrate to a different server. Unfortunately, all of its dependencies came out of the cheese shop (via easy_install/paste/et al), and it's apparently old enough that various versions of libs it requires are now gone from the cheese shop.
11:15	cemerick	old enough == 2 years :-/
11:15	stuartsierra	Yes, I've had the same problem with Ruby.
11:16	cemerick	on the other hand, a colleague of mine had a 5-year-old perl script that used some CPAN modules, and he got the thing running in about 4 minutes.
11:17	cemerick	I wonder if it's just a matter of stack complexity. A perl script is a far cry from a pylons/django/rails app, never mind a J2EE or Swing contraption.
11:17	cemerick	...and I don't see a lot of big, frameworky perl apps floating around
11:18	Fossi	if you come up with something useful, the world's gonna kiss your butt
11:18	stuartsierra	Perl certainly leans more toward small, independent modules rather than large frameworks.
11:18	Fossi	package management systems tend to be a bigger pita than the problem they are trying to solve
11:19	cemerick	stuartsierra: I wonder if there's any visualizations of the dependency networks of CPAN vs. the ruby/cheese shop/maven equivalents
11:19	Fossi	actually, the osgi stuff in eclipse is pretty nifty
11:20	cemerick	Fossi: yeah, and the netbeans module system does well, too (I forget its name). Focus certainly seems to help.
11:20	drewr	solves a direct problem in an ant-friendly way
11:20	Fossi	well, ant itself is a pita :)
11:20	Fossi	but i guess nothing that a little lancet wouldn't fix
11:20	cemerick	We used ivy for about 18 months, specifically because of its ant friendliness. Using it to track internally-produced dependencies ended up being too onerous, though.
11:20	Fossi	didn't get around to actually try it out
11:21	Fossi	but ifs in xml make me sick
11:21	drewr	cemerick: really? I just have my own repository and structure things the way it makes sense
11:22	drewr	really simple and without the complexity of maven
11:22	stuartsierra	Some info on CPAN dependencies: http://ali.as/top100/
11:22	cemerick	yeah, I totally agree. But for tracking dependencies between internal projects, it's way overkill
11:22	cemerick	vs. git submodules, say
11:23	drewr	cemerick: perhaps, but for the "please find and download these jars and put them in lib/" it's awesome
11:23	cemerick	yes, definitely
11:23	drewr	i have an allergic reaction to putting jars in VCS though :-)
11:24	cemerick	we've found that git submodule do the same job for us in a more straightforward way.
11:24	Fossi	then again, it would help if people released their jars with proper meta-data :D
11:24	cemerick	I did too, but we just create functionally-related dependency repos that hold only jars, etc.
11:24	drewr	i suppose if I had a jar-only repo submodules would work ok
11:24	drewr	ah, yes ;-)
11:24	cemerick	e.g. a UI dependency repo, a jdbc one, a couchdb one, etc
11:24	drewr	i do that for things like internal db auth info etc.
11:29	Fossi	is there a good style for (cond (some-test? some-param) some-param (some-other-test? some-other-param) some-other-param)?
11:30	drewr	Fossi: condp could probably help there
11:31	drewr	it gives you more of a switch-style cond
11:32	drewr	e.g. http://paste.lisp.org/display/80007,1/raw
11:33	Fossi	i don't even understand what the api wants to tell me :)
11:33	drewr	you give it the test you want to perform on the var, then the var, then the possible result->action combinations
11:34	drewr	,(condp class 10 String :string Integer :integer :else :foo)
11:34	clojurebot	java.lang.IllegalArgumentException: Wrong number of args passed to: core$class
11:34	Fossi	yeah, but if i get it right the test must be the same then
11:35	drewr	,(condp class 10 String :string Integer :integer :foo)
11:35	clojurebot	java.lang.IllegalArgumentException: Wrong number of args passed to: core$class
11:35	stuartsierra	drewr: you want "instance?"
11:35	drewr	,(condp instance? 10 String :string Integer :integer :foo)
11:35	clojurebot	:integer
11:35	drewr	stuartsierra: thanks :-)
11:35	drewr	forgot it was a comparison not a predicate
11:37	Fossi	so at least if test is the same, that'll work
11:38	Fossi	a kind of cond-let would be nice though
11:38	Fossi	ah, seems like contrib has one
11:39	drewr	if the tests are unique then cond probably makes most sense, or a map with dispatch fns
11:47	hiredman	or multimethods
11:47	hiredman	clojurebot: multimethods?
11:47	clojurebot	multimethods is what separates the boys from the men.
11:47	hiredman	clojurebot: multimethods is also <reply>multimethods are awesome!
11:47	clojurebot	'Sea, mhuise.
11:48	Chouser	also awesome: promises
11:50	Fossi	hmmm. i wonder how a multimethod could work out
11:50	hiredman	actually most likely pretty badly if you want cond-let
11:51	Fossi	problem is i have a string and want to check whether i know a tag that's similar
11:52	drewr	Fossi: paste an example of what you have and we'll try and clean it up
11:52	drewr	lisppaste8: url
11:52	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
11:52	hiredman	what is a tag? a keyword?
11:53	lisppaste8	FossiFoo pasted "untitled" at http://paste.lisp.org/display/83752
11:53	Fossi	nice pastebin
11:53	hiredman	if you turn your string into a keyword you can construct a hierarchy which multimethods can use for dispath
11:54	hiredman	oh
11:54	drewr	what does group-articles-by-tags return? articles?
11:54	Fossi	the tag is some other string i have stored previously
11:55	Fossi	well, the group-article-by-tags isn't really relevant, as i just want the tags. just didn't refactor yet
11:55	hiredman	seems fine
11:56	Fossi	if the (.toLowerCase tag-guess) is more expensive, i'd like to let it somehow
11:58	hiredman	I doubt it's very expensive
11:59	hiredman	just some subtraction
11:59	hiredman	,(int \A)
11:59	clojurebot	65
11:59	hiredman	addition
11:59	hiredman	cough
11:59	Fossi	no, it's not, but if i place another more expensive operation there
11:59	Fossi	like a fuzzy word-search or such
11:59	hiredman	,(char (+ 30 (int \A)))
11:59	clojurebot	\_
11:59	hiredman	:/
12:00	Fossi	i guess map and dispatch functions would be best
12:16	technomancy	would love to get feedback: http://github.com/technomancy/swank-clojure/tree/master
12:18	Jomyoot	IS there magick with Emacs to make Clojure coding faster?
12:19	Chouser	yes, but you have to feed it your soul first
12:19	technomancy	faster than what? =)
12:19	replaca	Jomyoot: clojure-mode, of course, slime, and paredit are my magic pieces
12:19	technomancy	yes, paredit is indispensable
12:20	replaca	paredit converts parens from enemies to friends :-)
12:21	Jomyoot	How about Textmate?
12:21	Jomyoot	Anytihng special for clojure?
12:22	technomancy	there's support, but last I heard it's fairly primitive
12:23	danlarkin	Jomyoot: it's nowhere near emacs for editing clojure code
12:23	Jomyoot	how about la clojure?
12:25	replaca	Jomyoot: don't know anything about la clojure
12:25	Jomyoot	gotta see demo for paredit
12:26	technomancy	slowly
12:29	replaca	Jomyoot: good thing to do is load it up, grab the cheat sheet and just play in an empty buffer. Then just start using it while writing code. At first it will be a little awkward, but pretty soon you'll get it in your muscle memory and not know how you did lisp without it.
12:29	cemerick	Jomyoot: enclojure provides maybe 60% of what you'd get in emacs w.r.t. editing s-expressions, with the additional upside that you won't go stark raving mad over time, and you'll spend time doing work instead of tweaking emacs. :-P
12:29	technomancy	re: paredit: http://p.hagelb.org/paredit-outline.html
12:32	Raynes	Looks like the AjClojure guy is looking for a new name. He said so on Twitter. Twitter don't lie.
12:32	Chouser	heh
12:32	Chouser	well, it's a good sign anyway
12:32	Jomyoot	awesome
12:33	cemerick	actually, a couple of clojure wrappers around NetBeans APIs would make it possible to put together every emacs-y things within that environment.....
12:33	technomancy	feedback welcome on that outline btw; I'm going to turn it into a screencast soon
12:35	Raynes	"AjClojure is a reimplementation of Clojure ideas using C# I should change the project name, AjSharpure?"
12:37	cemerick	ugh, that's so tortured.
12:41	hiredman	clojurebot: rhickey is also <reply>"The guy is totally awesome." -- Daniel Weinreb
12:41	clojurebot	In Ordnung
12:41	cemerick	hiredman: where'd that quote come from?
12:42	hiredman	http://stuartsierra.com/2009/02/22/its-about-the-libraries#comment-42489'
12:42	hiredman	er
12:42	hiredman	extra ' on the end there
12:42	technomancy	he's an author of the CL spec, right?
12:42	hiredman	one of them
12:43	hiredman	"Clojure is the future of Lisp" in there as well
12:43	drewr	he wrote LOOP for crying out loud!
12:43	cemerick	wow, that's a helluva endorsement.
12:44	hiredman	he did sort of qualify it with "in a production environment"
12:44	hiredman	but that ain't much of a qualifier
12:44	technomancy	hiredman: especially coming from someone who likes CL over scheme
12:49	technomancy	clojurebot: multiple inheritance is http://www.piratejesus.com/nerdcore/nerdcore017.gif
12:49	clojurebot	Alles klar
12:50	stuartsierra	He might have been referring to Scheme's use as an academic, teaching language.
12:53	cemerick	yeah, scheme still has an upper hand in that department, IMO.
12:53	Chouser	but it's so mutable!
12:54	cemerick	that's just an implementation detail
12:54	cemerick	I think PLT cons cells are immutable now
12:54	Chouser	maybe we need a teaching-clojure that keeps all the immutable goodness, but ditches all the JVM libraries in favor of cleanliness.
12:56	cemerick	hrm. Sounds like scheme. :-P
12:56	Chouser	hm
12:57	Chouser	scheme doesn't do mutable locals?
12:57	technomancy	Chouser: just don't teach people how to use any construct involving a dot, and you'll be in good shape
12:57	Chouser	setf or whatever its called?
12:57	technomancy	no need to change the language. =)
12:57	Chouser	technomancy: could be. I'm likely to have a chance to teach a kid programming and am trying to decide if clojure's a good fit or not.
12:58	technomancy	cool!
13:00	hiredman	I think a cool intro to programing class would be something like "learn lua by writing a lisp interpreter"
13:01	hiredman	where lua is lua, python, ruby, javascript, or something else
13:02	drewr	heh
13:03	hiredman	so you have a very directed course, and learn about the internals of a programing language
13:04	hiredman	you'd start by writing everything up in the host language, and has you get towards the end of the course you start replace bits and pieces in the implemented language
13:09	hiredman	homework "now that we have macros, replace special forms x y and z with macros
13:09	danlarkin	hard class if you're not used to FP!
13:09	hiredman	I don't think so
13:10	hiredman	I think it would be a great freshmen cs class
13:11	Chouser	many freshmen cs students at my school were still struggling a bit with simple loops half-way through the semester. a macro might be a lot to ask.
13:12	cemerick	we've all had our heads screwed up by typical CS stuff, when FP really isn't that hard
13:12	cemerick	...says the guy who has a particularly screwed-up head
13:13	cemerick	loops are hard -- or, really, mutability is hard.
13:13	hiredman	Chouser: someone somewhere will always stuggle, best to set the bar high so everyone can struggle together :P
13:13	Chousuke	There certainly exist people who really seem to be unable to learn programming.
13:14	Chousuke	I don't know if it
13:14	Chousuke	it's because of the imperativity or not, but hm
13:15	danlarkin	I don't remember where I heard this, but supposedly programming 101 professors fully expect 50% of their students to not grasp the material
13:15	replaca	after reading through the source of enlive, Christophe has me using -> all over the place. Dunno if it's a good idea or not.
13:15	technomancy	danlarkin: that was probably a lot worse back when programming was seen as a way to get rich
13:15	Chousuke	replaca: heh
13:16	Chousuke	I like ->, but it's certainly easy to abuse.
13:16	replaca	yeah, I haven't really figured out "best practice" yet. I'll keep using it til I decide where the limit is :-)
13:17	ataggart	My intro CS course used a pseudocode language the whole semester. I got a D. The second semester was in java; I got an A. Not sure what to make of that.
13:17	replaca	it does have a nice "pipeline-y" feel
13:17	hiredman	eww
13:17	hiredman	pseudocode
13:17	danlarkin	technomancy: heh, probably. From my experience pretty true, too. Lots of confusion about where to put semicolons versus squiggly brackets. C++ isn't the greatest intro language, granted, but still
13:18	technomancy	unless you count languages that are bad on purpose
13:18	danlarkin	brainf**k :)
13:18	replaca	ataggart: that's like trying to teach kids numerical analysis before 2 + 2 = 4. Noble, but flawed
13:18	hiredman	macros are actually pretty simple from the perspective of the implementing language
13:18	Chousuke	technomancy: is Visual Basic bad on purpose? :P
13:18	ataggart	lol
13:19	hiredman	thats why I am saying you start with something like lua
13:19	technomancy	Chousuke: teaching VB to beginners might be better than C++ because they'll realize how horrible it is sooner.
13:19	hiredman	function some-name (args) do-stuff-here end
13:19	technomancy	with C++ they'll just keep banging their heads against the wall thinking, "maybe I'm just not smart enough yet!"
13:19	hiredman	dirt simple readable syntax
13:20	Chousuke	hiredman: macros are very simple in principle. just a function of data structures to another data structure. I guess it's the details of effectively producing data structures that are also code that trip people up.
13:20	hiredman	Chousuke: it's not liked they'd have to write complicated macros, just replace a few previously (and careful selected for this purpose) "builtins" with macros
13:21	danlarkin	I think it's the runtime vs readtime that is tough
13:21	Chousuke	hiredman: like the common misconception that ` is somehow a special macro thing.
13:21	Chousuke	hiredman: or the hygiene issues when generating code. (which are actually completely separate from macros, as a concept)
13:22	hiredman	Chousuke: all of which would be skipped over
13:22	hiredman	which will make a horrible lisp interpreter, but this is a freshmen cs class
13:22	Chousuke	but then you would not be able to write very useful macros :/
13:24	hiredman	php.lisp is about 390 lines of php
13:26	hiredman	doesn't seem unreasonable for a quarter's worth of work
13:27	Chousuke	I saw a C lisp implementation somewhere once that was a single file and about a couple hundred lines of code.
13:28	Chousuke	it didn't have garbage collection though :)
13:28	hiredman	:\|
13:28	hiredman	you could always throw in boehm
13:28	Chousuke	heh.
13:28	technomancy	mine's 754 LOC
13:28	technomancy	(of Ruby though, major cheating)
13:30	hiredman	php.lisp uses php arrays as lists, which is sort of cheating I guess
13:30	Chousuke	(loop [] (print (eval (read))) (recur)); Cheating? Never.
13:30	Chousuke	not very useful though :(
13:31	technomancy	hiredman: I tried that in mine; it took me weeks to back myself out of that mistake
13:31	hiredman	the cool thing about implementing a programing language as the class goal, is there are all sorts of doodads you can fiddle and adjust and add in and take out
13:32	Chousuke	as a final assignment you could require them to write some simple program using their interpreter :P
13:32	hiredman	if, god forbid, the class is burning through the material, just throw in type-checking
13:33	hiredman	Chousuke: yeah, have them solve euler problems using it :P
13:59	rhickey_	http://clojure-log.n01se.net/ down since 7/11?
14:00	rhickey_	er, not down, but not logging?
14:01	cemerick	yeah, hopefully there's data somewhere. I was unceremoniously lost my connection yesterday in the middle of the binding discussion.
14:02	rhickey_	cemerick: yes, we lost you - you were saying?
14:02	cemerick	oh, I don't remember what my next step was
14:03	rhickey_	well you should now have everything you need for a neat with-binding solution
14:03	cemerick	yeah, that'll certainly work.
14:03	rhickey_	I got the batch-editibility fully going in the persistent vector last night and this morning - the perf is within 20% of ArrayList
14:04	Chouser	I've got the logs, but they're in the wrong format. I hope to get the site up this weekend.
14:04	cemerick	I thought about it for most of the night, and it seems like the general solution (short of copying bindings on the propagation of every value) is to add some functional demarcation to my cells impl. Right now, it's very open-ended, in that a particular "dataflow" can be added to at any time. Very flexible, but can lead to really large transactions (with-binding or not).
14:07	rhickey_	I'm still on the fence about read access to the mutable colls, e.g. there's nth! but not seq
14:07	cemerick	e.g. over here (/me waves his hands to the left) you've got a nest of cells that are UI-related, and over there you've got N other nests, each related to particular functional domains. When a value needs to be propagated from one nest to another, that should probably be a send to a "gateway" agent, which allows for some reasonable decoupling.
14:07	rhickey_	cemerick: sounds like a good idea
14:09	rhickey_	what's with all the "Whoa! I was listening to Sunn O))) and Rich Hickey started talking in the background and the music became creepier than before!" tweets?
14:10	cemerick	rhickey_: looks like they're all spammer accounts.
14:10	cemerick	pretty odd confluence, certainly
14:10	cemerick	odd bot behaviour
14:13	cemerick	rhickey: with-binding will solve direct future, pmap calls, etc., but it won't help with delays, etc., right? That'd require two calls -- one to capture the current bindings, and another inside the delay to apply them...I think.
14:14	cemerick	ach
14:15	cemerick	heh, my proggit submission re: Weinreb's comment got buried, not surprisingly
14:29	tashafa	hello.clj
14:29	Raynes	(println "What's up?")
14:30	tashafa	help... can some please explain how preduce works
14:31	Hun	,(doc preduce)
14:31	clojurebot	"clojure.contrib.datalog.util/preduce;[[f data]]; Similar to merge-with, but the contents of each key are merged in parallel using f. f - a function of 2 arguments. data - a collection of hashes."
14:31	tashafa	especially the (f base an-element-from the collection)
14:32	hiredman	~def preduce
14:36	tashafa	ah... it was the fact that it uses a reduce without an inital value in the source of preduce that was tripping me up
14:46	sh10151	if: Clojure installation step failed: git clone git://github.com/kevinoneill/clojure.git
14:46	sh10151	is this a temporary situation or is my code out of date?
14:46	sh10151	from clojure-install in clojure-mode
14:47	sh10151	the git error is "no matching repositories found"
14:48	hiredman	uh
14:48	hiredman	clojure moved to git, so there is an official github repo
14:48	hiredman	clojurebot: clojure?
14:48	clojurebot	clojure is far closer to perfection then python
14:49	hiredman	clojurebot: github
14:49	clojurebot	http://github.com/richhickey/clojure/tree/master
14:52	Chousuke	then :P
14:53	Chouser	hehe
14:57	hiredman	:/
14:57	hiredman	clojurebot: literal [?] clojure
14:57	clojurebot	11
14:57	hiredman	clojurebot: literal [1] clojure
14:57	clojurebot	cheating
14:58	hiredman	clojurebot: literal [7] forget
14:58	clojurebot	nothing defined
15:01	sh10151	hiredman: so clojure-mode needs an update?
15:01	hiredman	sh10151: dunno
15:01	sh10151	huh
15:02	sh10151	this was easy three months ago :-D
15:02	hiredman	where are you getting clojure-mode from?
15:02	sh10151	git://github.com/jochu/clojure-mode.git
15:02	hiredman	http://github.com/technomancy/clojure-mode/ seems to be the place
15:03	sh10151	i'm out of it for a while
15:03	sh10151	and everyone gets delusions of grandeur
15:03	Chousuke	jochu's is the original but techno's is more up to date.
15:04	sh10151	what do you use?
15:04	sh10151	i understand emacs is an acquired taste
15:04	hiredman	vim
15:04	sh10151	ah
15:04	sh10151	I think that's not popular at work either
15:04	Chousuke	vim is an acquired taste as well :P
15:04	cschreiner	bbbut I use emacs, and I love it
15:04	hiredman	I am not opposed to emacs per-se
15:04	sh10151	IDEA and Eclipse seem to be the systems of choice
15:04	hiredman	I just cannot be bothered
15:05	rsynnott	sh10151: for clojure?
15:05	Chousuke	I like both so I use viper with emacs.
15:08	sh10151	I'm trying to get my notebook set up with Clojure for a little presentation I'm doing
15:08	sh10151	"Clojure as an Interactive Java Shell"
15:29	ti381	IDEA and Emacs make me chuckle for clojure work
15:31	tashafa	~def memoize
15:32	tashafa	how do you print the source of a fn from the repl again?
15:34	Chouser	(source memoize) -- that's clojure.contrib.repl-utils/source
15:35	tashafa	ah
15:35	tashafa	thanks Chouser
15:46	sh10151	this clojure-mode clojure-install is giving me all kinds of trouble
15:47	sh10151	i think i will just do it all manually
15:49	ksclarke	hmm, I have clojure-contrib in my classpath but when I try to use mmap I get: "Unable to resolve symbol: mmap in this context (NO_SOURCE_FILE:6)"
15:49	ksclarke	I'm a complete newbie so I know I must be missing something obvious
15:49	ksclarke	the require for mmap worked fine
15:50	stuartsierra	"require" only loads the library. If you want to access it without a namespace, load it with "use".
15:51	ksclarke	ah thanks!
16:05	rzoom	anyone have any advice on passing an array of java strings to a java method?
16:06	rzoom	how would I construct a Java array of Java strings?
16:06	rzoom	(to-array ["abc" "def"])
16:06	Chouser	,(into-array ["abc" "def"])
16:06	clojurebot	#<String[] [Ljava.lang.String;@1673ef7>
16:06	Chouser	what are you starting with on the Clojure side? a seq of strings?
16:07	hiredman	,(.toArray ["a" "b"])
16:07	clojurebot	#<Object[] [Ljava.lang.Object;@11e356b>
16:07	hiredman	:(
16:07	rzoom	thanks!
16:08	rzoom	to-array wasn't quite working
16:08	Chouser	rzoom: right. to-array returns a Java array of Objects
16:09	Chouser	hm. I mean a Java array-of-Objects
16:09	rzoom	ahh.
16:09	rzoom	well, i just added create-ssl-server to contrib server-socket
16:10	Chouser	nice!
16:10	rzoom	will have to send it to the maintainer
16:10	Chouser	yep. You've seen http://clojure.org/patches ?
16:10	rzoom	i have now. reading ;)
16:25	hiredman	~works on my machine
16:25	clojurebot	http://haacked.com/images/haacked_com/WindowsLiveWriter/IConfigMapPathIsInaccessibleDueToItsProt_1446B/works-on-my-machine-starburst.png
16:31	rzoom	ok, showing my Java ignorance: is ant multithreaded?
16:32	rzoom	oh, i see that it can be.
16:40	stuartsierra	typically it isn't
16:41	rzoom	yeah, looks like the <parallel> tag is needed
17:41	rhickey	ok, if you want to play around with batch editing of vectors, the code is in the chunks branch: http://github.com/richhickey/clojure/commits/chunks
17:42	rhickey	lisppaste8: url
17:42	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
17:42	lisppaste8	rhickey pasted "batch editing of vectors" at http://paste.lisp.org/display/83767
17:47	mebaran151	is it possible to change the size of the agent thread pool?
17:47	hiredman	there are two agent threadpools
17:47	rhickey	mebaran151: the send-off pool grows as needed
17:52	mebaran151	alright thanks
17:58	Chouser	rhickey: looks pretty clean considuring the mutability
17:59	rhickey	Chouser: the idea is, write it the correct way, if it becomes your bottleneck, add mutable, !, !, !, immutable
18:00	rhickey	some open questions are - right now I disallow normal nth/get etc on the mutable version, must use nth!/get! etc
18:00	rhickey	although normal count works, hrm
18:01	rhickey	I don't want these things to be very useful if 'leaked'
18:07	Chouser	right
18:08	Chouser	I think that's valuable property
18:08	rhickey	I wonder how much pressure there will be for seq
18:08	rhickey	I imagine these used mostly for building/creating, but people might hang on to them for an extended time
18:09	hiredman	might be useful to have scoped mutability
18:09	rhickey	you could in fact use one as the value of an agent, simply (immutable @agt) whenever you want to read, as send ensures serial access
18:10	Chouser	gotta go. I'll try to work on irc log later
18:10	rhickey	Chouser: thanks
20:29	Chouser	oh, I just got what you were saying -- leave it mutable and each time you need to read use (immutable @agt)
20:31	rhickey	right
20:31	rhickey	not quite sure that will work, since there is not threading control at all
20:32	rhickey	in fact, will not work
20:35	Chouser	oh, because a flying read might break while the agent it updating the value?
20:35	rhickey	immutable copy must be given by same thread as mutation
20:37	Chouser	must be same thread, or just serialized with mutation?
20:37	rhickey	serialized, but not really a good story
20:37	Chouser	yeah
20:38	Chouser	thin plot, no character development.
20:38	rhickey	unhappy ending
20:40	Chouser	and agents were the best shot at leaving mutables hanging out in public -- sharing them other ways just gets worse
20:41	rhickey	there might be some variation of that idea though
20:42	rhickey	not too important
20:42	rhickey	the primary use is birth/batch
20:43	Chouser	are you worried about abuse? I'm not really, esp. if nth and seq fail.
20:44	Chouser	I'm sure you've thought of this, but it's easier to add capability than to take it away. So if seq and nth fail for now, and people have valid use cases for them, it'll be easy enough later to allow them to work.
23:36	duck1123	How do I specify code to be run as a destructor when using gen-class
23:36	Chouser	does java even support that?
23:37	duck1123	destructors? I thought they did...
23:37	Chouser	I seem to recall something called "finallize" but that it wasn't very reliable.
23:38	duck1123	hmm... it appears you're right
23:39	duck1123	I'm trying to open a connection to a xmpp server when my http server starts, and I want to make sure things are cleaned up when it shuts down
23:41	duck1123	unfortunately, compojure's defservice returns immediately. otherwise I would use the with-connection macro I wrote
23:42	Chouser	hm. maybe compojure has some kind of shut-down hook?