#clojure – 2009-08-13

2009-08-13

00:40	mebaran151	probably better than transcripts would be an introduction to modern Clojure for Schemers
00:42	Chouser	a transcript is more editable than a video presentation -- might be a decent place to start.
01:18	unlink2	Is #(Integer/valueOf %) the standard way to parse integers in clojure?
01:27	andyfingerhut	I don't know of any other way off hand, but I certainly don't know much of what is in all the Clojure libraries yet. It works. Go for it! :-)
01:31	hiredman	~everyone
01:31	clojurebot	Huh?
02:32	wavister	i'm trying to figure out how to create a collection A that contains a collection B that contains A. any advice? i can do it easily with mutable collections, but that's not ideal
02:33	wavister	something like (let [x [y] y [x]] x)
02:38	frodef	completely unrelated, but (let [x [y]] ..) shows an unfortunate aspect of the [] syntax, imho.. the square brackets are (too) overloaded.
02:38	andyfingerhut	I don't think that cycles are possible with immutable data structures like that.
02:39	wavister	not possible? ack... seems not very declarative of clojure
02:39	andyfingerhut	What leads you to want such a cycle?
02:39	andyfingerhut	Not saying you shouldn't. Just curious.
02:39	wavister	networks that connect both forward and backward
02:40	andyfingerhut	So like x and y are nodes in a graph, with lists of adjacent nodes for each one?
02:40	wavister	yeah
02:41	andyfingerhut	Seems like it should be possible to do that. Thinking...
02:41	andyfingerhut	Are the nodes just symbols, or some arbitrary data structures?
02:41	wavister	the goal is to avoid creating a top-down map. nodes shouldn't be able to access more than what's next to them
02:42	wavister	a node could have other properties, but mostly it's just a collection of it's adjacent nodes. potentially empty
02:42	andyfingerhut	I mean, I've done simple graphs in C/C++ where they could be represented as a vector of nodes, and each node had a vector of nodes adjacent to it, where each nodes was simply an integer
02:44	andyfingerhut	So a graph with 3 nodes 1, 2, 3, with edges between 1<->2 and 1<->3 would be represented by a vector [nil [2 3] [1] [1]]
02:44	andyfingerhut	(nil for the non-existent node 0)
02:44	andyfingerhut	That would represent the edges.
02:44	andyfingerhut	Other info about nodes or edges would need to be represented elsewhere.
02:44	wavister	yeah, it's the vector of nodes i'm trying to avoid. it's weird, i know. and there might be another way to do what i'm trying to do
02:45	wavister	the algorithm should have a node object, and have no access to the rest of the graph except through its neighbors
02:45	andyfingerhut	You're trying to avoid the vector in order to make it easy to arbitrarily add new nodes, without having to assign them a numerical index, or something like that?
02:46	wavister	yeah other nodes could be on other computers possibly
02:47	andyfingerhut	It seems to me like you need some kind of "indirection" to represent this, not via pointers, since you can't have them, but via something like some kind of identifiers for node names.
02:47	andyfingerhut	Then lists of edges are lists of node names.
02:47	andyfingerhut	You'd still need to look up those identifiers in some way, in order to traverse the graph.
02:47	andyfingerhut	i.e. get the edges for the next node in some walk
02:48	andyfingerhut	That doesn't have to be a vector. It could be a hash, if the node is stored on the local computer. But what would you do if it was stored on another computer? Send it some request over a network and ask for info about that node? Then you definitely need some kind of identifier, I think.
02:49	wavister	yeah, there could be a map that takes nodes as keys and has as values collections of other keys
02:49	andyfingerhut	And a way to know who to ask for info about that node in the graph.
02:50	wavister	yeah there would be a function for getting that other node from wherever it was instead of a reference, so they'd all have to be functions i suppose even if they just always return the same reference
02:50	wavister	okay i guess that's how i'll do it
02:52	wavister	thanks :)
02:52	andyfingerhut	np
02:53	wavister	oh crap, but the node still has to reference the map of nodes to nodes, which references said node. looks like it has to be mutable
02:54	andyfingerhut	The map of nodes to information about the nodes can be "well known", i.e. like a global thing.
02:54	andyfingerhut	Is there some kind of security or information hiding you're trying to enforce inside of your program?
02:56	andyfingerhut	Or you need multiple threads to make updated versions of this graph, and you want it to be possible to parallelize such updates?
02:56	wavister	well not really, to be truthful i'm mostly just playing around with concepts at this point. but i'm hoping it will evolve into something more serious
02:56	wavister	yeah it's the latter
02:57	andyfingerhut	I don't know if this will work, but you could try representing nodes as Clojure Refs pointing to information about the nodes.
02:57	andyfingerhut	Then part of that information could be a vector of other Refs for nodes that are adjacent.
02:58	wavister	i think that might be the way to go
03:01	andyfingerhut	I'd hack up a quick little toy program first to see if that basic idea works at all, or if there is something broken about the idea.
03:03	wavister	doing so :)
03:07	wavister	'(let [x (ref []) y (ref [])] (dosync (commute x conj y) (commute y conj x)) x)
03:08	wavister	,(let [x (ref []) y (ref [])] (dosync (commute x conj y) (commute y conj x)) x)
03:08	clojurebot	#<Ref@917cb0: [#<Ref@1913751: [#<Ref@917cb0: [#<Ref@1913751: [#<Ref@917cb0: [#<Ref@1913751: [#<Ref@917cb0: [#<Ref@1913751: [#<Ref@917cb0: [#<Ref@1913751: [#<Ref@917cb0: [#<Ref@1913751: [#<Ref@917cb0: [#<Ref@1913751: [#<Ref@917cb0: [#]>]>]>]>]>]>]>]>]>]>]>]>]>]>]>
03:08	wavister	looks good
03:08	andyfingerhut	We have different esthetics, then :)
03:09	wavister	heh. it should look like you're in one of those bathrooms with big mirrors on both walls...
03:09	andyfingerhut	I know what you mean. It ought to work.
03:10	andyfingerhut	You'll just want to make your own custom printing functions for debugging :)P
03:10	wavister	lol definitely
03:38	lloy0076	I'm trying to find an idiot's guide to installing the clojure-contrib and seem to see that there's a repository at sourceforge under SVN, one at github and then another group on google code...
03:39	lloy0076	It's possible I'm not looking in the right place for it - I've been staring at the wiki and www.clojure.org and various links and seem to have gotten a .jar from sourceforge...and that has download a heap of stuff in a trunk directory...
03:39	lloy0076	oops, it's not a .jar sorry (forgot to delete)
03:39	hiredman	lloy0076: sourceforge is old
03:39	hiredman	clojurebot: clojure contrib?
03:39	clojurebot	clojure is the brand
03:39	hiredman	clojurebot: contrib?
03:39	clojurebot	contrib is http://github.com/richhickey/clojure-contrib/tree/master
03:39	lloy0076	Whatever I got, seems to have built.
03:40	lloy0076	Ok, so I should figure out how to download it from github and build it from there?
03:40	hiredman	you don't want it from sourceforge
03:40	hiredman	sourceforge will be maybe six months out of date
03:40	andyfingerhut	Two most recommended ways would be: get latest clojure and clojure-contrib, both from github, or (2) get 1.0.0 version of Clojure from wherever, and 1.0-compatible version of clojure-contrib from github.
03:41	andyfingerhut	The latest stuff seems to work fine, and is probably easier to figure out how to get.
03:41	lloy0076	Ok, thanks. I believe I can figure that out - I got a tad confused between the s'forge and github one :)
03:46	lloy0076	@andyfingerhut and @hiredman (and @clojurebot) - thanks - problem fixed!
03:53	angerman_	how is the anatomy of those (with-xxx construct?
03:53	hiredman	eh?
03:54	hiredman	like with-open?
03:54	angerman_	(def xxx) (defn with-xxx [val & body] (binding xxx val body)) ?
03:54	andyfingerhut	you mean, how are they implemented?
03:54	angerman_	yes, like that
03:55	andyfingerhut	You can do (use 'clojure.contrib.repl-utils), then (source with-open)
03:55	andyfingerhut	at the REPL
03:55	andyfingerhut	Great learning tool.
03:55	hiredman	with-open is basically a let wrapping a try/finally
03:55	angerman_	I have a session object and I'm getting kinda confused with (let [session (get-session)] (to-session session key val) (from-session session key)))
03:56	hiredman	,(macroexpand '(with-open [a foo] stuf))
03:56	clojurebot	(let* [a foo] (try (clojure.core/with-open [] stuf) (finally (. a clojure.core/close))))
03:57	angerman_	so I'm wondering if I could simplyfy it by having a globaly bound one.
05:13	mikem`_	hi, newbie here. I have a string which I split with clojure.contrib.str-utils2/split, and I would like to assign the results to a map. starting with (split "First Last" #" ") I'd like to end up with {:first "First", :last "Last}.
05:15	clojure	using (source) with vimclojure repl, syntax hi-lighting, is fun ;p
05:17	andyfingerhut	You mean you want the keywords to always match the words split out of the string? That wasn't clear from your example.
05:17	mikem`_	andyfingerhut: yeah, ambiguous. let's try "Bob Smith" -> {:first "Bob", :last "Smith"}
05:18	mikem`_	the keys are predetermined and constant, I'm just filling in the map from a string
05:19	andyfingerhut	Getting there. Just having trouble with my home REPL to test out the return value of split
05:19	andyfingerhut	Don't recall it off top of my head.
05:19	mikem`_	andyfingerhut: apparently the return value of split is clojure.lang.ArraySeq which cannot be cast to clojure.lang.IPersistentStack (ie: pop won't work on it)
05:20	talios	you could (seq (split ...)) thou?
05:20	talios	I think
05:20	andyfingerhut	Try something like (let [[first last] (split ...)] {:first first :last last})
05:21	andyfingerhut	Not sure if you've seen destructuring before, but the extra [] around first last mean to treat the (split ...) return value as a sequence, and take the first element and bind it to first, and the second and bind it to last.
05:22	arbscht	,(doc zipmap)
05:22	clojurebot	"([keys vals]); Returns a map with the keys mapped to the corresponding vals."
05:22	andyfingerhut	Using the names first, last might lead to confusion in larger examples, given that those are also the names of commonly used functions (at least first is)
05:22	arbscht	,(zipmap [:first :last] ["Bob" "Smith"])
05:22	clojurebot	{:last "Smith", :first "Bob"}
05:23	mikem`_	andyfingerhut: ok, cool, that works :)
05:24	mikem`_	arbscht: thanks for that :)
05:25	mikem`_	ok, this works. but let's say I wanted to process each of "Bob" and "Smith" by passing it to some arbitrary function. how do I get it out of an ArraySeq?
05:26	andyfingerhut	The let form I showed is one way.
05:26	talios	,(doc seq)
05:26	clojurebot	"([coll]); Returns a seq on the collection. If the collection is empty, returns nil. (seq nil) returns nil. seq also works on Strings, native Java arrays (of reference types) and any objects that implement Iterable."
05:26	mikem`_	hm, I guess functions first will get me the first
05:26	andyfingerhut	Another is to do something like (let [a (split ...)] expression using (a 0) to get first element of a, and (a 1) to get second )
05:27	andyfingerhut	Hmm. Actually that is only if the return value of (split ...) is a vector, I think.
05:27	talios	,(seq (split "hello world"))
05:27	clojurebot	java.lang.Exception: Unable to resolve symbol: split in this context
05:27	talios	doh
05:28	andyfingerhut	(nth 0 a) will work for more kinds of things.
05:33	mikem`_	talios: can clojurebot pull in methods from clojure.contrib?
05:33	mikem`_	,(seq (clojure.contrib.str-utils2/split "hello world"))
05:33	clojurebot	java.lang.ClassNotFoundException: clojure.contrib.str-utils2
05:33	talios	I guess not :(
05:33	mikem`_	,(seq ('clojure.contrib.str-utils2/split "hello world"))
05:33	clojurebot	nil
05:34	andyfingerhut	,(use 'clojure.contrib.str-utils2)
05:34	clojurebot	java.io.FileNotFoundException: Could not locate clojure/contrib/str_utils2__init.class or clojure/contrib/str_utils2.clj on classpath:
05:34	talios	I can't remember who runs clojurebot either
05:34	mikem`_	,('clojure.contrib.str-utils2/split "hello world")
05:34	clojurebot	nil
05:34	mikem`_	,('clojure.contrib.str-utils2/split "hello world" #" ")
05:34	clojurebot	#" "
05:35	tomoj	what do symbols do as functions?
05:36	mikem`_	,(clojure.contrib.str-utils2/split "hello world" #" ")
05:36	clojurebot	java.lang.ClassNotFoundException: clojure.contrib.str-utils2
05:36	talios	,(use 'clojure.contrib.str-utils)
05:36	clojurebot	nil
05:36	talios	,(re-split #" " "Hello World")
05:36	clojurebot	("Hello" "World")
05:36	talios	regex win :)
05:37	tomoj	oh, just like keywords
05:38	talios	a symbol is a function that takes a map as an arg
05:38	talios	and a map is a function that takes a symbol
05:38	talios	kinda weird, but neat :)
05:38	tomoj	yeah, I knew keywords did that
05:38	tomoj	didn't know symbols did too
05:38	tomoj	also didn't know they took two args
05:39	tomoj	,('foo {} 3)
05:39	clojurebot	3
05:40	andyfingerhut	I wonder what kinds of resource limits are on clojurebot, if any? Not that I want to crash it or make this channel unusable, mind you, just curious :)
05:41	talios	forkbomb!
05:41	tomoj	(require '[clojure.contrib.str-utils2 :as s2])
05:41	tomoj	,(require '[clojure.contrib.str-utils2 :as s2])
05:41	clojurebot	java.io.FileNotFoundException: Could not locate clojure/contrib/str_utils2__init.class or clojure/contrib/str_utils2.clj on classpath:
05:41	andyfingerhut	I did that once, on a shared server at my college. The sysadmin kicked me off that system for months.
05:41	tomoj	it's in a sandbox
05:41	tomoj	dunno what all it does
05:43	arbscht	clojurebot is hiredman's creature
05:43	arbscht	clojurebot: clojurebot
05:43	clojurebot	clojurebot is like life: you make trade-offs
05:43	tomoj	10 second timeout looks like
05:44	tomoj	'Thread. is in a commented-out blacklist, but not the uncommented blacklist on github
05:47	tomoj	"Naked Singularity" wtf?
05:47	tomoj	clojurebot works with black holes?
05:49	andyfingerhut	Are you looking at clojurebot's list of patterns and canned replies?
05:49	tomoj	nope
05:50	tomoj	hiredman.horizon
05:50	tomoj	git b75cdb8b61e0fd4e83934e29d5ddaf78296ba7a7
05:51	tomoj	tomoj: git b75cdb8b61e0fd4e83934e29d5ddaf78296ba7a7
05:51	tomoj	:(
06:11	ole3	hi, how do i cast an Intger to an int?
06:11	cark	,(int 3)
06:11	clojurebot	3
06:11	opqdonut	:t fromIntegral
06:11	opqdonut	woops, thought i was in #haskell
06:11	opqdonut	sorry
06:11	opqdonut	i'll get my coat
06:11	tomoj	hmm
06:12	tomoj	isn't an Integer already an int?
06:12	tomoj	,(class 3)
06:12	clojurebot	java.lang.Integer
06:12	cark	Integer is the boxed int
06:12	opqdonut	,(class (int 1))
06:12	clojurebot	java.lang.Integer
06:12	tomoj	it gets boxed when you ask for its class?
06:12	opqdonut	yeah, probably
06:12	cark	yes
06:12	andyfingerhut	It gets boxed on every fn call.
06:12	andyfingerhut	so I've heard, anyway.
06:13	opqdonut	yeah, we need primitive type annotations
06:13	tomoj	well, anyway, there's no reason to cast, right?
06:13	opqdonut	well performance
06:13	opqdonut	(loop [i (int 0)] ...)
06:13	andyfingerhut	The primitive type annotations work fine within a loop/recur, inside of one function, but yeah, it would be nice if they could work across function boundaries, too.
06:14	cark	tht would be a gret performance boost
06:14	cark	+a +a
06:16	ole3	thank you
06:20	tomoj	opqdonut: I don't get it
06:20	tomoj	oh, yes I do
06:20	opqdonut	:D
06:21	andyfingerhut	Is it still funny if you have to explain it to someone?
06:27	Chousuke	I think Rich is planning on allowing longs and doubles as function parameters (and probably as return values too)
07:12	ChrisPS	Whenever I do something in the repl and get an error message (inside emacs), I am always returned something like: java.lang.ClassCastException: java.lang.Integer (NO_SOURCE_FILE:0)
07:13	ChrisPS	this NO_SOURCE_FILE, I would love to have that work
07:13	ChrisPS	can someone point a flashlight in front of my face?
07:15	cark	of you program in files and then load them, you should get a line number
07:16	cark	of/if
07:16	tomoj	ChrisPS: C-c C-k
07:16	ChrisPS	tomoj: what?
07:16	ChrisPS	compile?
07:18	tomoj	yep
07:18	tomoj	unfortunately it can only compile the entire file
07:18	tomoj	so.. everything has to work
07:19	ChrisPS	cark: that is the odd thing
07:22	ChrisPS	my compile is working just fine
07:25	tomoj	after C-c C-k you still get NO_SOURCE_FILE ?
07:29	ChrisPS	tomoj: right!
07:30	ChrisPS	mind you, I am a java noob
07:32	ChrisPS	so I might have some problems wrt source-file ref. etc.
07:32	ChrisPS	but everything else is working just fine (except for word-completion, but I think this is related...)?
07:33	ChrisPS	that's my analysis anyway
07:45	tomoj	oh hmm
07:45	tomoj	I just got NO_SOURCE_FILE too
07:45	ChrisPS	hehe, see
07:47	tomoj	oh wait
07:47	tomoj	nvm
07:47	tomoj	I don't get NO_SOURCE_FILE
07:47	tomoj	it depends on where the error is
07:48	tomoj	if the error is in the line you type into emacs, then you'll get NO_SOURCE_FILE
07:48	tomoj	if the error occurs inside a compiled function, you should see the filename and line number
07:48	ChrisPS	I have yet to see this, but ok for now
07:49	tomoj	do like (defn foo [] (map 1))
07:49	ChrisPS	usually when things blowup because of an exception or something, it responds with a NO_SOURCE_FILE:0
07:49	tomoj	when you C-c C-k, you should get a big stacktrace
07:49	tomoj	well, compile, then call (foo)
07:50	tomoj	somewhere down on the stacktrace you should see your filename
07:50	ChrisPS	user=> (foo)
07:50	ChrisPS	java.lang.IllegalArgumentException: Wrong number of args passed to: core$map (NO_SOURCE_FILE:0)
07:50	ChrisPS	user=>
07:50	ChrisPS	:-)
07:50	tomoj	uhh
07:50	tomoj	something's wrong with your slime setup
07:51	ChrisPS	I guess :-/
07:51	tomoj	you should get restarts with a full backtrace
07:51	ChrisPS	I always thought something was missing, since I did not see the Smalltalk effect
07:51	tomoj	what is "the smalltalk effect" ?
07:52	opqdonut	ChrisPS: use stacktrace
07:52	opqdonut	clojure.contrib.stacktrace
07:52	ChrisPS	the: instaneosly everything now, effect
07:52	opqdonut	see the docs
07:52	ChrisPS	opqdonut: ok
07:52	tomoj	but... it should do that by default
07:52	tomoj	ChrisPS: you did clojure-install?
07:53	ChrisPS	tomoj: not recently
07:53	tomoj	maybe you need to update clojure-mode?
07:53	ChrisPS	what is the easiest path
07:54	tomoj	I did emacs-starter-kit, install clojure-mode from elpa, then M-x clojure-install
07:54	tomoj	(well.. but then I deleted elpa clojure-mode since the clojure-test-mode from elpa still uses clojure.contrib.test-is)
07:54	ChrisPS	I've spent so much time reconfiguring emacs, that yeah, perhaps something got lost on the way
07:55	ChrisPS	regarding the stacktrace thing, when I (use it), I get a ClassNotFoundException etc...
07:55	ChrisPS	java.lang.ClassNotFoundException: clojure.contrib.stacktrace (NO_SOURCE_FILE:78)
07:55	ChrisPS	but what is this? a NUMBER??
07:55	tomoj	you have to require it
07:55	ChrisPS	ok
07:56	ChrisPS	(require 'clojure.contrib.stacktrace)
07:57	tomoj	that's funny, I don't see a clojure.contrib.stacktrace
08:01	ChrisPS	neither do I
08:02	tomoj	I'd just try starting with a fresh clojure-mode
08:02	ChrisPS	I think so too
08:02	Chousuke	hm
08:02	Chousuke	I don't see .stacktrace either.
08:03	Chousuke	... I'm sure it was there. :P
08:03	ChrisPS	mkaay
08:04	Chousuke	heh.
08:05	Chousuke	I see a clojure.stacktrace
08:05	Chousuke	:P
08:06	Chousuke	apparently it was moved over when .test was, too
08:10	cark	I'm trying to use memcached with clojure, it's a problem that the data structures are not serializable
08:11	cark	so in the meantime i'm printing these to a string and reading these from the string returned by memcached
08:11	cark	but it's slower
08:11	cark	so that defeats the purpose =/
08:12	cark	i understand the problem about serialization, how to serialize an infinite sequence ...
08:12	cark	but still that does not help =(
08:13	Fossi	i thought the persistent datascructures implement serializable
08:13	cark	i could not serialize (range 1 100)
08:14	Fossi	tried (vec (range 1 100))?
08:14	cark	but i'm a total noob when it's about java serialization
08:14	cark	yes that works
08:14	Fossi	i think you have to realize lazy things (naturally)
08:14	tomoj	(range 1 100) is a lazy seq
08:14	tomoj	which has the problem you just mentions
08:14	cark	right, but then i don't have a "universal" memcached serialization
08:15	Fossi	well, maybe only convert to string (or other token) if it's lazy
08:15	Fossi	then again, almost everything tends to be lazy :D
08:15	cark	if i need to walk the data structures i'll be as slow as the printer
08:16	tomoj	I don't get it, what's the problem with realizing before serializing?
08:16	Fossi	i'm having a similar inherent problem with exception handling
08:16	cark	you mean with lazy sequences ?
08:18	Fossi	cark: seen http://groups.google.com/group/clojure/browse_thread/thread/e704414cf36ef2aa?pli=1 ?
08:19	Fossi	rich suggests print/read too
08:19	cark	mhhh let me read that =)
08:19	tomoj	I don't think it's gonna help much
08:19	tomoj	most of the solutions involve serializing to some string form
08:19	Fossi	and and there is rarely anything else you can do
08:20	tomoj	what's missing serialization that needs it?
08:20	tomoj	ohh.. PersistentHashMap is, but Keyword isn't
08:21	Fossi	tomoj: well imho it's just the tradeoff of realizing your whole deep datastructure, against serializing to string
08:21	Fossi	a combination would be nifty (but impossible?)
08:21	tomoj	you have to realize the whole structure to serialize to string anyway, right?
08:21	cark	looks like i'm stuck with printing/reding
08:22	Fossi	well, you could try to keep lazy seqs and delay realizing them to read time
08:22	cark	there is still the problem with keywords ...
08:22	tomoj	huh?
08:23	cark	keywords are not serializable either
08:23	tomoj	how can you write a lazy seq to a string without realizing the whole thing?
08:23	Fossi	with exceptions a similar problem is to check for exceptions during realization, but also being able to stream the datastructure from jetty or such
08:24	Fossi	tomoj: don't know, just a thought. kinda keeping the function call around
08:24	Fossi	so serializing "(range 1 100)" instead of "1 2 3 4 ..."
08:25	Fossi	anyway, it has lot's of weird implications and prolly won't make sense in 99.9% of all cases
08:25	tomoj	yeah, guess that would work if it was pure
08:26	Fossi	would make one hell of a serializing framework thought if it would work
08:26	Fossi	i don't have a good solution for the exception problem yet
08:27	Fossi	it would be so nice if the exception handling would be "carried over"
08:27	cark	Fossi : you couldn't do it without language support
08:27	Fossi	but it's also really weird
08:27	tomoj	what exactly are you trying to do?
08:28	cark	yeah some kind of super-dynamic vars, these would be carried by the environement of the lazy closures
08:28	Fossi	tomoj: the use-case i had was in composure: i want to wrap every function i call in try/catch to not throw an exception at the user
08:28	Fossi	but i also might want to lazily stream things
08:29	tomoj	guess I don't know enough to understand why that's a problem
08:29	tomoj	oh, yeah, I see
08:29	cark	that wouldn't work as you might send the first part of your page, then get the error while realizing the sequence deep in your tree
08:29	Fossi	cdomposure doesn't let me set an exception handler for realization time
08:30	Fossi	so it realizes a function and one of my inner functions bails
08:30	tomoj	you _could_ do it in each part of the lazy seq, right?
08:30	tomoj	but I imagine that would be slow
08:30	Fossi	tomoj: yes, that would make quite some places to add try catch as well
08:31	Fossi	cark: exactly
08:32	Fossi	anywaz, it's more off an enhancement to composure really in this case
08:32	Fossi	but it felt weird when i discovered it
08:33	Fossi	and it's not really obvious that try catch doesn't work for lazy seqs
08:33	Fossi	especially since you (unknowingly) create/use them all the time
08:33	tomoj	so maybe compojure can try/catch while it's consuming?
08:33	Fossi	tomoj: yes, that's what i meant above
08:33	Fossi	and let me provide a handler
08:34	tomoj	I've been thinking about compojure lately
08:34	tomoj	it's very unopinionated
08:34	cark	i wouldn't say that
08:35	cark	it tries very hard to avoid state
08:35	cark	bit too much in my opinion
08:35	tomoj	well, that's part of the clojure territory I think
08:35	tomoj	I mean compared to, say, rails
08:35	tomoj	there are no opinions about how to structure your app really
08:35	cark	true
08:35	tomoj	which gives me the problem of designing such a structure :/
08:35	Fossi	yeah
08:36	Fossi	there are several aproaches as well
08:36	tomoj	I think my experience with rails is probably limiting my imagination
08:36	Chousuke	on the other hand, if you come up with a good design, you can make a framework on top of compojure that supports that design
08:36	Fossi	but actually i like compojure for not imposing a structure on me
08:36	tomoj	yeah, it's nice
08:37	Fossi	and i think the state handling is kinda ok as well
08:37	tomoj	guess compojure is sort of the equivalent of rack
08:37	Fossi	the request usage is a like awkward, but then again, that's more or less the only place one of our whole projects has a state
08:38	Fossi	can't do much else for the user session
08:38	eevar2	tomoj: neh. compojure is built on top of ring, which afaik is the equivalent to rack
08:38	Fossi	compojure is very cl-who'ish
08:38	tomoj	ok, so maybe compojure is half-way between rack and rails :)
08:38	Fossi	and it kinda just works ;)
08:39	tomoj	but I think in terms of like defcontroller, defaction, render, bindings over render for view variables, helper functions etc
08:39	tomoj	I think these concepts from rails are probably limiting me
08:39	Fossi	i dislike defserver etc for making me restart jetty :(
08:39	tomoj	wonder if I can find some apps written in compojure on github...
08:40	eevar2	i've rewritten all my compojure apps a gazillion times w/o coming up with a design i'm happy with
08:40	Fossi	especially because i have to restart slime then because my layout is too dumb
08:40	eevar2	s/all/both ;)
08:42	tomoj	Fossi: hum?
08:42	tomoj	you mean layout like html layout?
08:42	tomoj	I found I could just recompile my handlers without even restarting jetty and changes would happen
08:42	tomoj	but I just did a trivial hello world
08:43	Fossi	no, my clojure file
08:43	Fossi	if you defserver, the old server variable is gone
08:43	Fossi	but you need it to stop the jetty
08:43	cark	use multiple file, one that initialize your server, and another one for routes/implementation
08:43	tomoj	ah, I see
08:43	Fossi	but using def*, you need to recompile to get the changes
08:44	tomoj	what do you think about autoloading files like rails does?
08:44	Fossi	so if you forget to stop the jetty before compiling, you have to restart slime. at least that's the easiest way to get rid of the process i've found so far
08:44	cark	i just handed out a fairly large compojure application to a customer, and only seldom had to restart the whole thing during developement
08:44	Fossi	tomoj: well, you can recompile almost everything
08:44	Fossi	just not the defs
08:45	tomoj	def..whats?
08:45	Fossi	route being the most common case
08:45	Fossi	defserver, defaction, defroutes etc
08:45	tomoj	ah
08:45	tomoj	do they generate anonymous functions or what?
08:46	Fossi	no, they call def, creating a var
08:47	Fossi	well, they also create a heap of anonymous functions, but that's not the problem
08:47	tomoj	but if the var has the same name, wouldn't the def just overwrite the old value?
08:47	tomoj	just like recompiling defn does?
08:49	Fossi	for defserver, you loose the reference to the server then, but it still runs
08:49	tomoj	yeah that one makes sense to me
08:49	Fossi	for defroutes there was similar problem. let me look
08:49	tomoj	actually...
08:49	tomoj	I did it with defroutes and had no problem
08:50	tomoj	at least I thought I did
08:50	Fossi	yeah, ok, that problem is more on our side of the code
08:50	Fossi	we have two defroutes, one using the other
08:50	tomoj	ah I see
08:50	Fossi	and the secondary doesn't get reread
08:51	Fossi	and the primary is in the same file as the defserver call ;)
08:51	Fossi	so it prolly would work, if i didn't use C-c C-k
08:51	Fossi	and compiled everything needed seperately
09:58	Fossi	it's really funny: i just realized that most of the code i've recently written in javascript is functional
09:58	Fossi	and i document or mark the few occasions of global state explicitly
09:59	Fossi	makes me wonder how much of that habit will carry over to java
10:27	ole3	hello, is it possible to do bitwise or in clojure?
10:28	cark	,(doc bit-or)
10:28	clojurebot	"([x y]); Bitwise or"
10:28	ole3	thank you
10:30	ole3	hm, bitwise or of n arguments where n is greater 2?
10:31	ole3	ah... (reduce bit-or args)
10:31	cark	,(reduce bit-or 0 [1 3 7]) ?
10:31	clojurebot	7
10:32	ole3	:)
10:32	cark	i was too slow i guess =)
11:02	Chousuke	heh, I forgot Clojure pattern literals don't need to escape \
11:03	Chousuke	Got a bit confusing when the pattern that I copied verbatim from LispReader source wasn't matching my floats :P
12:21	cemerick	~max
12:21	clojurebot	max people is 164
13:08	m3lling	Anyone here a fan of StackOverFlow.com?
13:08	m3lling	I'm trying to get people to gather small Clojure examples into a question that I asked.
13:08	m3lling	http://stackoverflow.com/questions/1261557/whats-the-most-useful-thing-youve-done-in-less-than-50-lines-of-clojure
13:09	m3lling	Put a 250 point bounty on it.
13:13	technomancy	m3llingl: personally I'm still trying to get over the idea of using a web application built in ASP.NET. apart from that it seems decent. =)
13:18	cark	technomancy : there might be more of these than you might think
13:18	cark	lots of intranets i guess
13:19	technomancy	cark: well specifically for a web app targeted towards programmers. I'm sure there's plenty of news sites etc. that use it.
13:19	cark	well .net programmers are programmers too
13:20	cark	and i woud say they have much merit =)
13:20	technomancy	cark: Stack Overflow is the first community I've seen that has much overlap between Windows devs and the rest of the world.
13:22	cark	true
13:22	cark	same goes for java
13:22	cark	it really on it's own planet
13:22	cemerick	it's a huge improvement for people that generally don't have a high-quality community (e.g. asking Java questions in Java-focussed forums is really painful)
13:25	cark	but is really stackoverflow ASP.net ? or just .net somehow connected to the web ?
13:27	cark	ok yes it is
13:36	jweiss_	how come when i call load-file, a java class i refer to in that file (inside a defn) is being instantiated, its static initializer fails because it's being called too early, i want it to wait until i actually call the function
13:38	cark	maybe you have some code calling that function in your file ?
13:38	cark	try adding a print statement and see how it goes
13:38	jweiss_	cark: no, i don't call the function anywhere
13:39	cark	would you care showing the code of this function ?
13:39	jweiss_	cark ok
13:40	jweiss_	cark, what paste website do you guys use
13:41	cark	clojurebot: paster?
13:41	clojurebot	Gabh mo leithscéal?
13:41	cark	clojurebot: paste?
13:41	clojurebot	lisppaste8, url
13:41	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
13:41	technomancy	you know what I could really use? an introduction to the quirks of the JVM that isn't written for a Java programmer.
13:42	lisppaste8	jweiss_ pasted "untitled" at http://paste.lisp.org/display/85329
13:42	technomancy	I have no idea how properties files are used, and I keep running into problems from multiple classloaders that confuse me.
13:42	technomancy	anyone know of an article like that?
13:42	jweiss_	cark ^^
13:43	jweiss_	oh um i think i get it, it's because i used def
13:43	jweiss_	i thought if i used it inside a function it wouldn't get called until runtime?
13:43	jweiss_	how do i create a reference to this java object that i can refer to throughout this file?
13:44	jweiss_	(at runtime)
13:45	cark	right
13:45	cark	you don't use def inside a function
13:45	jweiss_	cark: what is the right way
13:45	cark	use let
13:45	jweiss_	cark, but i want to be able to refer to this instance in other functions
13:45	cark	(let [test-script TestScript.)] ..use it here)
13:46	jweiss_	let is local
13:46	cark	allright
13:46	cark	put a (def test-script (atom (TestScript.))) outside the function then
13:46	cark	but you said you don't want it to be instanciated early
13:46	jweiss_	cark, but i don't want it to run at load time
13:47	jweiss_	right
13:47	cark	so you (def test-script (atom nil))
13:47	cark	then when you want to instanciate it (reset! test-script TestScript.)
13:47	cark	but
13:47	cark	that's the wrong way to go about doing this kind of stuff
13:48	cark	not very idomatic
13:48	cark	not very functional
13:48	jweiss_	cark: yeah, i am looking for the idiomatic way
13:48	jweiss_	i know its not functional, but i'm stuck with this java class
13:48	jweiss_	that has methods i need to call
13:48	cark	i don't quite know about selenium
13:48	cark	but usually you want to have a clojure function that will return a result
13:49	cark	so you can create your java objects in a let
13:49	cark	and pass these along
13:49	jweiss_	i don't want to create a new instance in every function call
13:50	cark	well at some point you have a top-level state object, with all the state of your program
13:50	jweiss_	yeah, that's this testscript object
13:50	cark	you can pass the script object already created to all your functions
13:50	jweiss_	using the atom, reset! stuff you mean?
13:50	jweiss_	oh i see
13:50	Chousuke	use refs for state
13:51	cark	well if it's a top level object, it's ok to use the atom stuff
13:51	Chousuke	refs are designed so that the value they reference varies over time, with well-defined semantics for how the reference changes.
13:52	Chousuke	atoms can change at any time, without any coordination
13:52	jweiss_	Chousuke: i'm just looking to set this once, and never change it
13:52	jweiss_	but i don't want to set it at load time, rather at run time
13:52	cark	Chousuke : you don't want to manipulate a java object in a dosync
13:53	Chouser	jweiss_: sounds like a good job for an atom
13:53	Chousuke	an atom might be okay. or a function that returns a singleton.
13:53	Chousuke	ie. inits on first call, returns the object on subsequent calls.
13:53	jweiss_	Chouser: ok, i'll give that a shot. Chousuke: how do you return a singleton in clojure
13:53	jweiss_	Chousuke: oh i see
13:54	Chousuke	I think you would usually use a local atom for that though :P
13:54	cark	global state is evil !
13:54	Chousuke	but at least it would be local, so no evil user could go and change it.
13:54	Chouser	yeah, that's even better. close over an atom with a singleton-access fn
13:55	Chousuke	cark: global coordinated references to immutable values are not :)
13:55	Chousuke	oh, the language has become sentient!
13:55	Chouser	(let [thing (atom nil)] (defn get-thing [] ...))
13:55	clojure	(fear)
13:56	Chouser	maybe it's just recursion. clojure has joined #clojure has joined ##clojure...
13:57	cark	Chousuke : agreed, though it's best to have as little of that as possible
13:57	jweiss_	ok so i changed it to an atom that i reset! in my function. still get java.lang.ExceptionInInitializerError (console.clj:0)
13:57	jweiss_	when i load it in the repl
13:58	cark	show us the new code =P
13:58	cark	probably a little oversight
13:58	lisppaste8	jweiss_ pasted "untitled" at http://paste.lisp.org/display/85330
13:59	jweiss	how do i get it to colorize properly
13:59	cark	well i'm positive that this is not run on load =/
14:00	jweiss	cark: remember, it's the static initializer that's being run
14:00	jweiss	so maybe it runs on import?
14:00	stuartsierra	The compiler might run the static class initializer when the class is first referenced.
14:00	jweiss	i thought that only ran when you create an instance of the class... but maybe it's even earlier, when the class is loaded?
14:01	jweiss	i guess i should look this up
14:01	cark	maybe some magic hapenning in the imported name spaces
14:01	jweiss	yep, "you can also write static initializer blocks to initialize static variables when the class is loaded."
14:02	jweiss	well, i am gonna have to do some work to move that code out of the java class's initializer block
14:02	jweiss	and into somewhere where it runs later
14:17	technomancy	OK, I'm pretty stumped about this. I'm trying to set some properties for the jets3t library. Dropping a jets3t.properties file in the classpath seems to have no effect according to System/getProperty.
14:17	technomancy	first of all, is that a good way to check for properties?
14:18	technomancy	I mean, are library-specific properties going to be present as system properties, or will they be loaded elsewhere?
14:19	lrenn	technomancy: just dropping the properties files won't add them to the System properties.
14:19	brool	I think you need to load them explicitly, don't you?
14:20	lrenn	http://java.sun.com/j2se/1.4.2/docs/api/java/util/Properties.html
14:20	brool	http://www.factorypattern.com/how-to-readwrite-java-properties-files/
14:22	technomancy	lrenn: right, but the jets3t library should be loading them
14:22	technomancy	sorry, should have mentioned that
14:22	technomancy	http://jets3t.s3.amazonaws.com/toolkit/configuration.html doesn't say where the file goes, but in the root of a dir on the classpath is pretty standard
14:22	technomancy	right?
14:25	lrenn	technomancy: right. But I don't think checking System/getProperty is a test to see if they got loaded.
14:25	technomancy	OK, I'm just not sure what the conventions are here. I guess jets3t should expose its own Properties object somehow?
14:26	stuartsierra	technomancy: yes
14:26	jweiss	can we use the .. macro to call java like this: testscript.getTasks.createUser("blah") - where the last call has args?
14:27	stuartsierra	jweiss: yes: (.. testscript getTasks (createUser "blah"))
14:28	jweiss	stuartsierra: thanks
14:30	Chouser	or (-> testscript .getTasks (.createUser "blah"))
14:31	lrenn	technomancy: https://jets3t.dev.java.net/source/browse/jets3t/src/org/jets3t/service/Jets3tProperties.java?rev=1.18&view=markup
14:32	technomancy	lrenn: right; I can construct my own jets3t properties object by passing in a filename
14:33	technomancy	but if I don't know what filename it's going to use by default, that's not going to help
14:33	technomancy	I need a way to grab the properties object that's currently in use.
14:33	lrenn	technomancy: http://jets3t.s3.amazonaws.com/api/org/jets3t/service/Jets3tProperties.html
14:34	lrenn	technomancy: You already know the filename it's going to use by default.
14:36	technomancy	lrenn: ah... I see. it wasn't working with "/jets3t.properties", but removing the initial slash fixed it.
14:36	technomancy	go figure
14:39	Anniepoo	has anybody written a little swing GUI repl you can embed in a clojure app for debugging?
14:39	technomancy	now to throw hadoop into the mix and watch it all explode. =\
14:46	stuartsierra	technomancy: but it will explode in parallel!
14:46	Chouser	Anniepoo: I have one in my "textjure" project.
14:46	jweiss	anyone know an existing fn to convert camel case to lisp case?
14:46	Chouser	In fact, that's about all it is so far. Though not designed to be embedded in another app, I wouldn't expect it to be too difficult.
14:46	technomancy	stuartsierra: I can now have twenty cores all ignoring my properties file at once! can't say that's not progress.
14:47	stuartsierra	oh yeah
14:47	technomancy	stuartsierra: do you use s3 with hadoop at all?
14:48	stuartsierra	A little, mostly just copying stuff between S3 and HDFS.
14:48	technomancy	yeah, I'm distcping stuff over to S3 and getting lots of BS "Response '/packed' - Unexpected response code 404, expected 200" warnings without any actual errors.
14:48	technomancy	crazy stuff. =\
14:49	stuartsierra	Yeah, it'll do that, but distcp retries on error.
14:49	technomancy	it's causing the mappers to fail for me.
14:49	technomancy	so I'm trying to increase the retry limit
14:50	technomancy	oh! I think I got it. I need to export HADOOP_CLASSPATH to a dir that has the jets3t.properties file in it
14:50	b4taylor	I think I've asked a few times but a better solution was always found so I never needed it, but can I give a type hint saying that something is an arry of doubles or something?
14:50	b4taylor	I just get back a 2d array of Objects.
14:50	technomancy	putting it in conf/ alone doesn't cut it
14:50	stuartsierra	technomancy: yes
14:50	b4taylor	Which may not be a problem, but I'd rather see Double[][] from my (into-array-2d foo)
14:51	stuartsierra	Also, the Hadoop JARs include a copy of JetS3t, which may have its own properties file.
14:52	lrenn	technomancy: are you doing this from the repl/slime with your clojure-project?
14:52	technomancy	lrenn: no, hadoop must be run from the shell
14:52	technomancy	it's very tedious
14:53	stuartsierra	You can run it via the API, but it's not well-documented. I've never figured it out.
14:54	technomancy	stuartsierra: we've got that working, but it's so different from distributed mode that it's nearly useless for debugging real issues
14:54	technomancy	I mean, if you've already got your code factored out sanely
14:55	technomancy	write as much as you can in regular clojure interactive slime style, and then go to slow batch processing for figuring out all the crazy hadoop quirks
14:56	stuartsierra	Right, that's what I tried to implement in my clojure-hadoop library.
14:56	technomancy	the problem with Clojure/FP is that the interesting problems get solved so easily that you end up spending all your time on the boring infrastructure BS like this.
14:56	Chousuke	heheh
14:56	stuartsierra	I think that's true of programming in general.
14:56	clojurebot	that is not what I wanted
14:57	technomancy	stuartsierra: it's just more noticeable when your language is more streamlined
14:58	stuartsierra	yes
14:58	jweiss	what is the significance of # in task#, in this line: (let [task# (apply instantiate-task ant-project ~(name ant-name) props#)]
14:58	jweiss	is it just part of the name?
14:58	stuartsierra	I'm suffering through WSDL right now.
14:59	technomancy	stuartsierra: my condolances
14:59	Chousuke	I wonder if it'll be a problem for my reader that it might consume more from a stream that it needs to read a single object :/
15:00	technomancy	Chousuke: that's why you need a PushbackReader IIRC
15:00	technomancy	in the current implementation
15:00	Chousuke	technomancy: yeah, but my current reader design doesn't work with anything stateful.
15:00	Chousuke	it just wants a seq of lines.
15:00	technomancy	gotcha
15:02	Chousuke	it shouldn't be too difficult to "push back" any leftover stuff after a read has been completed though.
15:03	Chousuke	but then it would complicate the line numbering ;/
15:05	Anniepoo	What's not to like about a language you already like, when you're stuck in a long debug cycle, and you realize instead of wishing for a debugger you could HAVE one.
15:06	Chousuke	I suppose the reader could claim ownership of the stream and then any operations on the reader input the user might want to do should be on the (immutable) reader data structure.
15:06	Anniepoo	11:35 I start writing one - 11:40 I realize undoubtedly one exists and ask, 11:47 Chouser suggests where to get one, 11:53I notice his message, but mine's done already
15:16	b4taylor	Do you know a sane way to get a 2d array of doubles?
15:16	b4taylor	argh
15:16	b4taylor	Chousuke: Do you know a sane way to get a 2d array of doubles.
15:19	Chousuke	I avoid arrays in Clojure code to the best of my ability :P
15:19	b4taylor	Unfortunately I'm interfacing to a matrix library :p
15:19	b4taylor	I suppose I could just write a pure clojure library.
15:20	b4taylor	I doubt it would be slower, and I just need the basic operations. I don't need solving or anything.
15:20	stuartsierra	,(make-array Double/TYPE 3 5)
15:20	clojurebot	#<double[][] [[D@1d433c1>
15:20	b4taylor	Ahha.
15:21	b4taylor	Then I just have to copy the data over.
15:21	b4taylor	stuartsierra: I'll play with this. Thanks.
15:21	stuartsierra	np
15:23	b4taylor	Also, I suppose I should ask for a good lisp macro how-to before I ask for a clojure one.
15:25	lrenn	jweiss: it generates a unique symbol.
15:25	jweiss	lrenn: thanks
15:28	lrenn	http://clojure.org/macros is pretty sparse.
15:36	jweiss	can someone tell me whats wrong w this macro (trying to defn a function that is just a wrapper for a java method, using memfn):
15:36	jweiss	(defmacro define-task [task-name]
15:36	jweiss	`(def ~task-name (memfn (.. @testscript getTasks ~task-name))))
15:36	jweiss	i get java.lang.IllegalArgumentException: Malformed member expression (repl-1:15)
15:38	stuartsierra	memfn only works on isolated symbols
15:38	andyfingerhut	If you want lots of examples and discussion of macros, book length, then Paul Graham's On Lisp is a Common Lisp specific book on them, but a lot of them translate well to Clojure. http://www.paulgraham.com/onlisp.html Probably more than you want right now, though :)
15:39	cemerick	isn't memfn long deprecated at this point (by #()?)
15:39	jweiss	cemerick: it's still in the Programming Clojure book
15:39	cemerick	ah
15:39	stuartsierra	,(defmacro define-task [name] `(defn ~name [script#] (.. script# getTasks ~name)))
15:39	clojurebot	DENIED
15:40	jweiss	stuartsierra: thanks
15:40	Chousuke	it's not deprecated I guess but I don't think anyone uses it :P
16:20	jweiss	if i have a vector of args i want to pass to a java method, how do i unpack the vector to call the method
16:22	hiredman	jweiss: easiest way is to wrap the java method call in a function and use apply
16:23	hiredman	,(let [f (fn [s p r] (.replaceAll s p r))] (apply f "foo" ["o" "a"]))
16:23	clojurebot	"faa"
16:23	jweiss	hiredman, maybe i should go up one level. i'm trying to write a macro that just creates function wrappers for all the member methods on a class
16:24	hiredman	:(
16:24	hiredman	jweiss: I would just write function wrappers as needed
16:24	jweiss	i'm having trouble dealing with methods with args tho
16:24	jweiss	hiredman, i can't it has to be dynamic :)
16:24	hiredman	why?
16:25	jweiss	because my prog won't know beforehand what all the methods on this class are, it will just know at runtime
16:25	hiredman	what does that have to do with any thing?
16:26	jweiss	how can i write a wrapper for a method before i even know what class i'm going to be using
16:27	jweiss	oh, i think what you're asking is why wouldn't i just use the java method directly
16:27	jweiss	i just want a cleaner syntax
16:27	jweiss	because i want other people to be able to use this
16:30	cemerick	jweiss: about the only difference you'll see is the lack of a period before method names
16:30	cemerick	,(.size [])
16:30	clojurebot	0
16:30	cemerick	-> (size [])?
16:31	cemerick	it's too bad proxy doesn't allow one to put docstrings in their usual spot
16:32	jweiss	cemerick: yeah sorta, i was actually using (.. @myobjatom (method args)) -> (method args)
16:32	jweiss	or actually
16:33	cemerick	(.method @youratom args) is more idiomatic
16:33	jweiss	(.. @myobjatom getTasks (method args))
16:33	hiredman	and -> is kind of prefered over ..
16:33	hiredman	(-> myobjatom deref getTasks (.method args))
16:34	cemerick	well, I'd keep the @, but sure :-P
16:34	jweiss	k
16:34	cemerick	jweiss: the java interop syntax is virtually transparent -- enjoy it :-)
16:35	hiredman	I can tell which functions I created though messing around at the repl and which I just sort of typed out by the use of →
16:35	jweiss	cemerick: hopefully my other team members won't be thoroughly confused. clojure is completely foreign to them
16:35	hiredman	the repl functions always have a bit long → call
16:35	jweiss	then again, so is most programming, so what is the diff right
16:36	jweiss	eventually i'm going to make a UI, but was hoping for a repl to be usable enough
16:36	cemerick	indeed -- shock them with concision
16:42	jweiss	there isn't any way to really build javadoc into classes so it's available at runtime, is there.
16:42	jweiss	that sucks
16:52	cemerick	That will change eventually. We'll need that capability before we can release the next version of our main product.
16:54	Chouser	Java's going to compile javadoc right into the classfiles?
16:59	jweiss	i can't believe they didn't allow for annotations to hold javadoc
16:59	cemerick	Chouser: wha?
17:00	cemerick	oh, hah, I didn't read jweiss' comment properly
17:00	cemerick	I thought he was talking about generating javadoc from clojure code (e.g. gen-class, newnew)
17:01	cemerick	not sure how I misunderstood that :-/
17:01	cemerick	misread*
17:01	Chouser	ah
17:02	Chouser	does that mean generating a sort of stubbed out .java?
17:03	cemerick	Yeah, almost certainly. We dove into that a little bit some months ago, if you'll recall.
17:03	Chouser	hm, I don't. I maybe be blocking the memories.
17:03	cemerick	I did some spelunking into javadoc, and it's a super-gnarly javac sidecar that is entirely unextensible.
17:04	cemerick	I thought that's where gen-interface originally came from, but maybe I'm inventing whole cloth over here.
17:08	cemerick	hrm, what is #_ used for? It's defined in LispReader, but unused in core.
17:10	Chouser	It comments out an expression.
17:10	hiredman	,(do 1 #_2)
17:10	clojurebot	1
17:10	Chouser	,[1 2 #_ (oh no goin crazy here) 3]
17:10	clojurebot	[1 2 3]
17:12	cemerick	yeah, I figured that from the LR impl. I just can't think of any reason to use it...
17:12	cemerick	just inline comments, where (comment ...) is too much?
17:13	cemerick	oh, I see, it doesn't evaluate to nil
17:19	Chouser	exactly.
17:23	cemerick	annotations will be the death of us all
17:24	Chouser	I don't even know what they are.
17:24	Chouser	As far as I'm concerned, if Clojure doesn't support it, it doesn't exist. :-D
17:25	cemerick	it's only a matter of time before clojure supports them. The whole Java multiverse is tilting in their direction.
17:25	Chouser	yes, this does present logical paradoxes when I try to write new features for clojure.
17:35	mebaran151	I never really got their point, but probably clojure could quarantine annotations with the rest of its Java compromise
17:36	mebaran151	I also was wondering whether or not, based on Clojure's compilation model, anonymous fn's were ever garbage collected
17:36	mebaran151	if each fn gets it's own class, it would seem that using lots of clojures would rapidly fill up the permgen
17:37	Chousuke	lots of clojures? :P
17:37	technomancy	mebaran151: iirc that was a problem a while ago, but it's been addressed
17:37	cemerick	as code transformation mechanisms, they're simply nutty; for controlling code generation and runtime configuration in one spot, they're better than the alternative (e.g. like wedging stuff into a superclass or put into an XML file or whatever)
17:38	cemerick	mebaran151: an anonymous fn still has just one class.
17:38	cark	mebaran151 : closures are really like a class
17:38	cark	so the environement is an instance of that class
17:38	cark	and instances can be garbage collected
17:40	cemerick	,(doseq [x (range 2)] (println (class #(list))))
17:40	clojurebot	sandbox$eval__2445$fn__2447 sandbox$eval__2445$fn__2447
17:41	mebaran151	no I see
17:42	mebaran151	cemerick, but if you just had a large application with lots of anonymous functions, it seems like wedging them into the superclass would be preferable, though I guess at any given time you might want to run that code path
17:43	cemerick	mebaran151: are you referring back to annotations?
17:46	mebaran151	nah, I'm being unclear
17:47	mebaran151	in a really large app, it seems like clojure might force you to suffer from class bloat
17:47	mebaran151	'though I guess each class is small enough individually
17:47	cark	well we don't see these classes
17:47	mebaran151	that it's not like in some Java servlet apps I've seen
17:47	cark	you mean for the user ?
17:47	cemerick	well, I think class GC is off by default in most VMs, though there's an option
17:48	cemerick	Unless you're actually defining new fns regularly, I don't think there'd be enough class definition to cause a problem.
17:50	hiredman	the class gc can also be an issue for java, I've seen reports of redeployments on tomcat eventually filling the permgen space
17:50	cark	but the fix technmancy refered to should shield us from that , isn't it so ?
17:51	cark	my understanding was that everything was in it's own class loader
17:51	mebaran151	hiredman, that's what I was referencing: I've had to redeploy on Jetty
17:51	mebaran151	and if you have many many classes, I've noticed weird GC behavior on this one app I put up
17:52	hiredman	cark: I dunno if it is complete fix
17:52	hiredman	it might fix some clojure specific issue
17:52	cark	well every eval (and so the compiled code) should be garbage collected
17:53	cark	but i don't know how that applies to loaded code
17:53	cark	is there a class loader per defn ?
17:53	cark	or per anonymous function even
17:57	cemerick	I wonder if it'd be worthwhile to define a binary serialization mechanism, so that arbitrary Serializable object could be dropped in in-line
17:58	hiredman	it would be pretty easy with #=
18:00	cemerick	ugh, doesn't seem like a good move -- one would have to encode the binary serializations. I was thinking of going the other way, emitting binary for clojure data structures, with java-serialized graphs in-line.
18:01	cemerick	readable clojure is nice, but big (esp. strings and such)
18:01	hiredman	cemerick: you could do that
18:01	hiredman	just wrap the binary in #=(read-binary-chunk ...)
18:01	Chousuke	you need to base64-encode it too :/
18:02	cemerick	yeah, that's what makes any use of #= sorta pointless
18:02	hiredman	I guess
18:03	cemerick	It'd be pretty easy to emit the core data structures via DataOutputStream, etc.
18:05	Chousuke	hmm
18:05	Chousuke	how do you serialise infinite seqs though? :P
18:06	cark	serialize the underlying lambda !
18:06	Chousuke	hm, I guess it's not so difficult. you'd just have to serialise whatever produces the next value.
18:06	Chousuke	(in addition to the values so far, of course)
18:07	cemerick	not even that, I think. Just some marker to start a map, read pairs until you hit a terminating marker, etc. Recurse, and done.
18:13	hiredman	I thought the marker to start a map was {
18:14	cemerick	ah, I had thought that DataOutputStream packed bits. So yeah, standard delimiters would work fine.
18:41	cemerick	heh, java regex Patterns are serializable, but not interned. I didn't expect that...
18:42	cemerick	actually, I didn't expect that they wouldn't override equals and hashcode based on the pattern string. That's more like it. :-)
19:55	arrayman	I've looked all over, but can't seem to find the right syntax for an array argument in gen-class
19:58	_mst	I've done something like this before: (defn -read-char<>-int-int [this cbuf off len] 456)
19:58	_mst	but I haven't tried it recently :)
20:01	arrayman	@_mst Thanks; does that automatically get added to the .class as an instance method because of its name, or do I have to mark it as such?
20:03	_mst	I think it's just based of the name, yep. In that case I was overriding this method of StringReader: "int read(char[] cbuf, int off, int len)"
20:03	_mst	the full example's here if you want to try it: http://dishevelled.net/Tricky-uses-of-Clojure-gen-class-and-AOT-compilation.html
20:05	arrayman	I remember reading that article, but was under the impression that I had to give the method that special name _and_ tag it inside the gen-class invocation. Thanks for setting me straight.
20:07	arrayman	@_mst I notice that -read-char<>-int-int matches the argument signature (char array and two ints), but how does the return type get specified?
20:10	_mst	it doesn't in that example, but I'm not sure you'd need to
20:10	clojurebot	that is not what I wanted
20:10	_mst	does java actually let you dispatch on return type too?
20:14	arrayman	@_mst I don't believe it does, so maybe I'm fretting about nothing.
20:15	arrayman	@_mst Does the same naming apply to static methods?
20:16	_mst	I've never done much with static methods and gen-class, sorry. But can you really override static methods anyway?
20:16	arrayman	@_mst I'm creating a brand new class, not overriding
20:17	_mst	ah I see
20:17	arrayman	@_mst ...and I've been able to define other static methods on it -- but haven't been able to specify an array type at all.
20:50	mrsolo	http://4.bp.blogspot.com/_syI_yyzTPG8/SnDhboxfNZI/AAAAAAAAATk/4cyx7jJ4XLc/s1600-h/chart1_jruby.5.png
20:50	mrsolo	ack!
20:50	mrsolo	and i though jruby is slowest of them all...
20:56	cemerick	mrsolo: that's why libraries are so important. e.g. who cares that the sort fn uses java.util.Arrays/sort?
20:57	cemerick	mrsolo: where'd that graphic come from?
20:57	mrsolo	http://berlinbrowndev.blogspot.com/2009/07/jvm-notebook-basic-clojure-java-and-jvm.html
20:57	mrsolo	i haven't went through the details
20:58	mrsolo	but this is the first benchmark that shows jruby is faster than clojure
20:58	mrsolo	usually it is another way around..
20:58	cark	he's filtering twice
20:59	cemerick	shrug both JRuby and clojure should (and do, at least in clojure's case) use Java's sorting routines
21:01	mrsolo	should but this is intentional
21:01	mrsolo	guess he is trying to determine the overhead of various jvm langauges.
21:01	cemerick	yeah, I suppose it's an interesting exercise.
21:02	cemerick	quicksort certainly benefits from the use of a mutable data structure. :-P
21:03	cark	the java example doesn't really mutate stuff
21:09	cemerick	cark: LinkedLists are most certainly mutable.
21:10	cark	right, but they are only used like our own mutables
21:14	cemerick	hardly -- the clojure code is doing two filters on each pass, vs just accumulating results.
21:15	cark	yes yes
21:15	cark	i mean the linked lists while being mutable are used in a way that won't interfere with the outside of the function
21:16	cark	in the same way we're supposed to use the new mutable data structures in clojure
21:17	cark	but yes i wouldn't do the quicksort in clojure that way, not for speed ... though the ruby version is not any better
21:19	mrsolo	ya jruby version is pretty crappy
21:19	mrsolo	still faster
23:08	avital	hi. is there an equivalent to filter for hashmaps?
23:08	Raynes	Filter works for maps.
23:09	avital	i'm looking at the source code and it seems that pred only gets one argument. i want to filter based on the keys, not the values.
23:12	hiredman	avital: the seq of a map is a seq of [key value] pairs
23:12	avital	ah nice ok cool
23:12	hiredman	,(seq {:a 1 :b 2})
23:12	clojurebot	([:a 1] [:b 2])
23:13	hiredman	,(filter #(= 1 (val %)) {:a 1 :b 1 :c 3})
23:13	clojurebot	([:a 1] [:b 1])
23:13	hiredman	,(into {} (filter #(= 1 (val %)) {:a 1 :b 1 :c 3}))
23:13	clojurebot	{:b 1, :a 1}
23:13	avital	wow what wow wow
23:13	avital	what is #(
23:13	avital	and what is val
23:13	avital	and %
23:13	avital	WOW
23:14	avital	is #( a really quick way to define a fn
23:14	avital	where % is its arg?!
23:14	hiredman	yes
23:14	avital	INCREDIBLE
23:14	hiredman	but it is not equiv to (fn [] )
23:14	hiredman	with #() there is no implicit do
23:14	hiredman	well
23:14	avital	hmmm not sure what that entails
23:14	hiredman	more that that
23:14	hiredman	#(foo 1) => (fn [] (foo 1))
23:15	hiredman	#(1) => (fn [] (1)) => an Exception
23:15	avital	ah i see
23:15	avital	so wait what is val?
23:15	hiredman	,(doc val)
23:15	clojurebot	"([e]); Returns the value in the map entry."
23:15	hiredman	,(class [1 2])
23:15	clojurebot	clojure.lang.LazilyPersistentVector
23:15	hiredman	grrr
23:16	hiredman	,(val [1 2])
23:16	clojurebot	java.lang.ClassCastException
23:16	hiredman	bah
23:16	hiredman	,(class (first {:a 1}))
23:16	clojurebot	clojure.lang.MapEntry
23:17	avital	thanks this is great
23:56	Chouser	any suggestions on an easy way to un-chunk a seq?
23:56	Chouser	, (chunked-seq? (seq [1 2 3]))
23:56	clojurebot	true
23:57	Chouser	,(chunked-seq? (seq (map first (take-while identity (iterate next [1 2 3])))))
23:57	clojurebot	false
23:57	Chouser	surely there's something better than that.