#clojure – 2009-11-11

2009-11-11

00:01	timothypratley	what's a usage for (ints ...)?
00:03	timothypratley	,(ints (make-array Object 1))
00:03	clojurebot	java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [I
00:03	timothypratley	Is that intended? I can't think of a scenario where "ints" would do anything useful, but it must exit for a reason :)
00:05	technomancy	it's not useful for pure-clojure; it's intended for java interop
00:05	timothypratley	I just need something for a test I'm writing, any ideas?
00:06	timothypratley	(otherwise I'll just leave it out)
00:07	_ato	timothypratley: ints is usually used for type-hinting
00:09	timothypratley	_ato: ints type hint is different from ints function
00:10	timothypratley	,(doc ints)
00:10	clojurebot	"([xs]); Casts to int[]"
00:10	_ato	ala (defn foo [int-array] (let [local-array (ints int-array)] ...))
00:11	_ato	similar to how you'd do the same thing with int, to perevent boxing
00:11	_ato	at least that's what I always assumed it was for
00:13	_ato	don't think you can test that, as there's no way to know whether it got unboxed ;)
00:14	timothypratley	hmmm ok good :)
00:14	timothypratley	thanks
00:15	timothypratley	,(ints (int-array 1))
00:15	clojurebot	#<int[] [I@9f017d>
00:15	timothypratley	I wonder if that's a false sense of security
00:45	codyK	anyone using maven together with swank-clojure-project?
00:46	codyK	I'm a little confused about how swank-clojure-binary should be getting set, since maven seems to keep jars in a single repo rather than in the individual project directories
00:52	codyK	hrrm, looks like perhaps doing mvn clojure:swank on commandline and then connecting to it from emacs is the way to go
01:44	twbray	Watching thousands of lines of +PrintGCDetails output... what fun
04:07	michaeljaaka	Hi!
04:16	michaeljaaka	Is there any live?
04:17	michaeljaaka	Just curious
04:19	Chousuke	I guess it's silent time right now :P
04:30	somnium	question for silent time: why is eval frowned upon?
04:31	somnium	~eval
04:31	clojurebot	eval is evil
04:31	michaeljaaka	eval
04:31	michaeljaaka	~do
04:31	clojurebot	Titim gan éirí ort.
04:31	michaeljaaka	hmmm bot could be an intteractvie help
04:32	somnium	he speaks irish when you confuse him
04:32	michaeljaaka	instead of looking into doc I would type here a function name and get an answer
04:32	somnium	he does that already
04:32	michaeljaaka	how?
04:32	somnium	,(doc eval)
04:32	clojurebot	DENIED
04:32	somnium	he really doesn't like eval I guess
04:32	michaeljaaka	.(doc do)
04:33	michaeljaaka	.(doc ->)
04:33	michaeljaaka	hmmm
04:33	michaeljaaka	doc ->
04:33	somnium	I have a list of expressions like '(+ foo bar baz), and foo bar baz gets looked up in the database and replaced, and I call map eval
04:33	michaeljaaka	doc do
04:33	somnium	it works like a charm but eval makes me feel dirty
04:33	somnium	(doc do)
04:33	clojurebot	Titim gan éirí ort.
04:33	somnium	,(doc do)
04:33	clojurebot	I don't understand.
04:33	somnium	,(doc ->)
04:33	clojurebot	"([x form] [x form & more]); Threads the expr through the forms. Inserts x as the second item in the first form, making a list of it if it is not a list already. If there are more forms, inserts the first form as the second item in second form, etc."
04:34	michaeljaaka	doc let
04:39	raek	why use eval when one have macros?
04:40	raek	anyway, I haven't used eval this far...
04:40	raek	but it is there, which means you are free to use it
04:41	somnium	its in a layout like: {:title "foo" 1 id-1 2 id 2 :func '(+ (- foo bar baz))}
04:41	raek	why not #(+ (- foo bar bax)) ?
04:41	raek	where is the code created?
04:41	somnium	because foo bar baz don't exist
04:42	somnium	they have to be resolved at runtime
04:42	somnium	its similar to a macro, but the information isn't available at compile time
04:42	raek	ah, then perhaps eval is best the way
04:42	somnium	its quite convenient in any case
04:43	raek	my personal opinion is that you should use it
04:43	raek	as long as you control the code generation
04:47	raek	but this is just my opinion, more experienced people might have different ones
05:13	piccolino	Any feedback on my little CSV library would be helpful. http://github.com/davidsantiago/clojure-csv
05:14	Maddas	raek: Why would macros change anything about the need for eval?
05:14	Maddas	Oh, sorry, this was addressed just afterwards.
05:23	raek	piccolino: sounds like a useful lib
05:24	piccolino	my first real clojure code.
05:27	raek	looks good :)
05:27	piccolino	Thanks.
05:28	raek	however, it's good to have doc and author metadata in (ns ...)
05:28	piccolino	For all the functions?
05:28	raek	like the various clojure.contrib libs have
05:29	raek	no, a general description of the whole file
05:29	raek	like:
05:29	hiredman	clojurebot: web dev?
05:29	clojurebot	web dev is the worst dev
05:29	piccolino	Oh yeah, OK.
05:29	piccolino	I'll look at how to do that.
05:29	raek	otherwise, it's well documented
05:31	raek	(ns
05:31	raek	#^{:author "Stephen C. Gilardi",
05:31	raek	:doc "def.clj provides variants of def that make including doc strings and
05:31	raek	making private definitions more succinct."}
05:31	raek	clojure.contrib.def)
05:31	raek	like that ^
05:32	raek	clojure.contrib uses that alot
05:32	raek	maybe you should add the csv code there...
05:33	piccolino	To clojure-contrib?
05:33	raek	simple data formats are good candidates for clojure-contrib. imho
05:33	raek	yes
05:33	piccolino	Hm, well, glad to do that, if they'll have it.
05:34	raek	one of the things I love about clojure is how easy it is to parse data in a lazy way
05:35	piccolino	Yeah, I originally wrote it not lazy, without even thinking about it.
05:35	piccolino	And then changing it to be lazy was pretty easy, very little change.
05:37	raek	how does the output look like? seqs of seqs of strings?
05:37	piccolino	The output of a CSV parse is a sequence of vectors of strings.
05:38	piccolino	Each vector of strings is a row.
05:45	raek	I really like that clojure libs tend to be build to emmit data in simple data structures
05:46	piccolino	Yeah, you should see somnium's MongoDB library.
05:46	piccolino	It's fantastic. Just turns clojure data structures in MongoDB documents and vice versa.
05:48	piccolino	Goodnight.
05:48	somnium	glad you like it, but that's more thanks to mongodb's data format than my efforts
05:48	piccolino	And thanks for your help.
05:48	piccolino	somnium, that's true, but we were praising clojure here.
05:48	piccolino	You couldn't do the same thing with Scala or Java.
05:49	somnium	true, the scala mongo code I've seen doesn't look pleasant
05:49	somnium	but that might be scala's fault
05:49	somnium	clojurebot: tell me about scala
05:49	clojurebot	Scala often gets in the way when trying to write neat code -- seen in #scala
05:50	piccolino	I thought it was just the static typing. You can't really take some data struture you made and use in your code, and have it automatically be turned into mongo stuff. Very easily.
05:52	somnium	I started on scala once or twice, but it always gave me a headache. (I just wanted to try out Lift, really)
05:52	piccolino	Yeah, I found Scala just before Clojure.
05:52	piccolino	Didn't really feel like it was saving me much time and effort over Java after a while.
05:53	somnium	clojurebot: tell me about scala
05:53	clojurebot	{((x: Any, y: Any) => (f: Function2[Any, Any, Any]) => f(x, y))(1, 2)((x: Any, y: Any) => x)}
05:53	somnium	^ my head hurts
05:53	piccolino	Love that type inference.
05:53	piccolino	That was what killed me. I sure had to type out a lot of types for a language that had type inference.
07:28	AWizzArd	~max people
07:28	clojurebot	max people is 197
08:09	raek	(into {} (map fn-making-pairs coll))
08:09	raek	is this ideomatic?
08:11	somnium	fn-making-pairs is returning vectors?
08:12	raek	yes
08:13	raek	a sequence of vectors of size 2
08:15	somnium	then it works fine with fn-making-pairs
08:16	somnium	as I'm sure you're aware
08:16	raek	there's also: (merge (map fn-making-maps coll))
08:16	somnium	that would create a vector though
08:16	raek	if fn-making-maps returns {<key> <value>}
08:17	somnium	ah, yes, didn't notice you changed the name
08:17	raek	somnium: which?
08:17	raek	ok
08:18	raek	so, are both equally good?
08:18	somnium	I think it depends more on the function
08:18	somnium	I mean, if you have this function, and you want to make it into a vector or a map, what you showed was fine
08:19	chouser	raek: I think into is preferred
08:19	raek	also, the function would only return a signle key-value pair
08:19	somnium	raek: I would go with chouser on this one
08:20	chouser	at least right now on HEAD, into uses transients and so is likely faster
08:20	raek	ok, thanks!
08:20	raek	maybe merge is better when merging maps with more associations
08:21	raek	then I'll continue to use into...
08:23	chouser	right, if you already have fn-making-maps and esp. if it can return larger maps then clearly you need to use merge
08:23	chouser	well, (apply merge (map ...)) right? But without those constraints I think 'into' is more common.
08:34	raek	chouser: ah, yes. forgot apply
08:36	chouser	'merge' could use transients
08:42	somnium	(reduce conj {} ...) seems to be very slightly faster than (reduce into {} ...)
08:43	somnium	(2/10s of a second per 1,000,000 on my old laptop), I guess into is firing up a new loop on every iteration?
08:52	chouser	somnium: for a large number of small maps, conj appears to be faster. For a small number of large maps, into seems faster.
08:53	chouser	either could overtake the other as the functions mature.
08:56	somnium	chouser: good to know, thanks
08:56	chouser	sigh http://golang.org/
08:56	somnium	I saw that
08:57	somnium	I thought, that could make a great platform for clojure :)
08:57	somnium	if only it could link to C libs
08:57	somnium	(I'm not sure that it can't, but it wasn't mentioned anywhere)
08:58	blackdog`	why the sigh chouser? another missed opportunity, or ...
08:59	chouser	it comes bundled with libs. like a "simple regex lib" that understands . but not (?>X)
09:00	blackdog`	it's still experimental i guess,
09:00	blackdog`	they do mention regex needs more advanced functioality
09:00	cemerick	I don't quite grok its raison d'être
09:01	chouser	well, that's more a datapoint suggesting the state of the useful libraries.
09:02	somnium	it seems kind of like D with message passing (though D can link to C AFAIK)
09:02	chouser	languages already demand so much of their users: leran the primitives, learn the semantics, learn the data types, learn the APIs, learn the configuration and deployment environments, and so on.
09:02	cemerick	yeah, I was going to say, they're a little nuts when they say that "No major systems language has emerged in over a decade". D is quite a big leap forward, and has some degree of momentum.
09:03	cemerick	plus the C linkage, as somnium said
09:03	chouser	it seems to me that new languages should strive to reduce that set while making their differences as clear and beneficial as positive.
09:05	chouser	instead we get this kind of thing -- learn all the above, plus our own new syntax, plus you'll have to re-write regex and xml parsers and parser generators and just everything from scratch.
09:05	fogus_	The approach to language design is typically, look at the big pile of paradigms, pick a few, tweak a few things here and there. Tada... ne language
09:06	fogus_	rhickey: yep
09:06	chouser	good guess!
09:06	chouser	they asked me why I sighed.
09:06	rhickey	Google is sure squatting on some terms with Closure and Go
09:07	cemerick	the FAQ makes it sound like they'd like to stop writing C at google. I'll bet they have far different requirements in that context than any of us do.
09:07	chouser	yeah, you'd think they'd know more about SEO
09:07	AWizzArd	what is it about this Go thing?
09:07	cemerick	chouser: don't worry, they'll make sure the results are How They Should Be.
09:07	chouser	cemerick: heh
09:07	fogus_	They know all about SEO... my guess is that golang will be the #1 hit for "Go" any day now
09:08	chouser	oh, how nice! the standard lib inluces a PNG image decoder
09:08	fogus_	cemerick: beat me to it ;)
09:08	cemerick	chouser: is that a big deal?
09:09	chouser	cemerick: it's goofy. I guess if you have to build all your libraries from scratch, you have to start somewhere. Maybe png image decoders (but apparently not jpeg?) is where you start. shrug
09:11	chouser	"goroutines"
09:11	cemerick	all those billions in advertising funny-money will pay for a lot of go coding monkeys in some random google playground. I'll bet libraries won't be a problem soon enough.
09:12	chouser	cemerick: could be, and would still be unfortunate.
09:12	cemerick	I agree.
09:12	cemerick	This is the sort of thing that happens when an organization simply has too much money.
09:12	chouser	cemerick: if that happens, I'll probably have to learn it eventually, though I've managed to avoid learning PHP so far.
09:12	Chousuke_	Go actually didn't seem too bad.
09:13	chouser	that won't last though -- the shop I work for has a lot of PHP. ...it's just a matter of time now...
09:13	cemerick	chouser: well, you're a PL masochist, AFAICT :-)
09:14	gbt	at least you're not being pushed onto cobol sob
09:14	chouser	gbt: good point
09:16	chouser	suddenly a day of writing unit tests in clojure doesn't look so bad. Thanks, Google!
09:16	gbt	well at least my misfortune wasn't met with snickers ;)
09:17	Chousuke	At least Go has the right idea about interfaces.
09:17	Chousuke	It'll be interesting to see if anyone actually starts using it.
09:20	fogus_	The best part so far appears to be the .go file extension. That looks pretty cool.
09:20	chouser	the fact that "why does go not have macros" isn't even on the list is telling.
09:21	somnium	I wonder if this is that language yegge was blogging about
09:21	chouser	nah, yegge was talking about his own version of javascript
09:28	ordnungs`	hi all
09:28	chouser	ordnungs`: hello
09:34	ordnungswidrig	just another day, just another programming language is born
09:37	rhickey	new language, new backend for cinc
09:43	ordnungswidrig	cinc?
09:44	chouser	ordnungswidrig: http://blog.n01se.net/?p=41
09:47	adityo	hello folks
09:47	jabley	ordnungswidrig: turtles
09:47	chouser	heh
09:47	adityo	,(import '(java.util UUID))
09:47	clojurebot	java.util.UUID
09:47	adityo	,(. UUID randomUUID)
09:47	clojurebot	#<UUID ab96c396-0685-4cc5-9a2c-161b42cb2f29>
09:48	adityo	but when i do the same thing inside a ns and file, i am getting an error
09:48	chouser	that format sure is tenacious
09:49	chouser	adityo: what error?
09:51	adityo	chouser: java.lang.IllegalArgumentException: Don't know how to create ISeq from: Symbol
09:51	chouser	adityo: from the 'import' line, right? are you doing it inside an 'ns' block?
09:53	adityo	chouser: sorry my bad, got the issue, my function didnt have the args []
09:53	chouser	np.
09:53	gbt	I'm waiting for the day when I don't feel stupid :)
09:53	chouser	,(UUID/randomUUID)
09:53	clojurebot	#<UUID 1e245222-746c-4ae1-889a-8ea118f68c86>
09:54	chouser	btw, that ^^^ is the preferred form for static method calls these days.
09:55	adityo	yes i changed it to that form
09:56	chouser	oh dear http://en.wikipedia.org/wiki/Go!_(programming_language)
10:00	ordnungswidrig	As long as they dont call is gojure....
10:00	chouser	heh
10:01	ordnungswidrig	is cinc a current project or will is be addressed "later", say after clojure 2.0 or like that?
10:02	chouser	ordnungswidrig: much of the work rhickey has been doing lately (reify, deftype, protocols) will directly support cinc
10:02	chouser	he's also mentioned though that he wants at least more release before those go into the master branch.
10:03	ordnungswidrig	sounds reasonable
10:05	AWizzArd	I think when the changes of New go into Master it is maybe time for a new release, such as 1.1 or something like that?
10:06	cemerick	I confess I don't see an obvious use case for protocols in my work, although it's entirely possible I'm not grokking them fully.
10:06	chouser	AWizzArd: I think 1.1 is going to happen before the 'new' branch merge.
10:07	somnium	is a 1.1 rc close? (only issues I've had have been naming, c.c.test-is -> c.test, -> c.c.walk c.walk)
10:09	ordnungswidrig	how can I macroexpand in the repl?
10:09	rhickey	cemerick: do you use interfaces?
10:10	chouser	,(macroexpand-1 '(dosync a b))
10:10	clojurebot	(clojure.core/sync nil a b)
10:10	somnium	ordnungswidrig: are you using slime?
10:10	ordnungswidrig	chouser: Doh! I missed the '
10:10	ordnungswidrig	somnium: yes
10:11	cemerick	rhickey: certainly. But then, I'm happy enough to use deftype or reify as necessary. I'm rarely consuming others' libraries, so I don't often need to 'inject' interface impls for a given type.
10:12	somnium	ordnungswidrig: C-c C-m macroexpands the expression at point into a new buffer
10:12	rhickey	cemerick: really? - you never wished, say, String, could play along with an API you built without putting in an if(x instanceof String) ... ?
10:12	chouser	'defprotocol' can't be used to define a host interface, right? The only time I've bothered to define interfaces, they need to be consumable by Java.
10:12	chouser	oh, except for finger trees. that will use protocols
10:13	rhickey	chouser: no, defprotocol will be completely dynamic
10:13	ordnungswidrig	somnium: oh, nice. Didn't know this would work in the repl, too.
10:14	rhickey	In any OO shop I've been in, our own libraries and apps had become large enough that saying 'just derive from MyInterface' was no longer workable
10:15	cemerick	rhickey: I'm sure it happens occasionally, but I can't say it's frequent enough to become irritating. I might have simply internalized the pain, tho. :-)
10:15	Chousuke	rhickey: Could there be a way to generate a Java interface from a protocol though?
10:15	cemerick	The functional footprint of our Java codebase is rapidly shrinking relative to our clojure codebase. That makes things easier :-)
10:15	rhickey	Chousuke: quite possibly
10:16	rhickey	cemerick: are you using multimethods?
10:16	cemerick	rhickey: yes, but often not dispatching on a single arg's type :-)
10:17	rhickey	hmpf
10:20	cemerick	I wouldn't fret about it -- if it makes it easier to build and maintain the core data structures, that well worth the price of admission for me.
10:21	chouser	how many requests have been made to backport bug fixes or features to Clojure 1.0?
10:21	Chousuke	I suppose protocols will still break a dependency on Java. It should help porting eg. contrib to other Clojure hosts if libraries in contrib defined protocols and then used those instead of direct JVM calls.
10:21	rhickey	cemerick: I predict deftype+ defprotocol will be huge
10:21	cemerick	I'm sure. Part of my issue is that I'm so married to interfaces mentally, that I'm sure I'm not seeing the big picture.
10:22	rhickey	they are just more powerful interfaces
10:22	rhickey	don' t require derivation
10:22	rhickey	dynamic
10:22	rhickey	can be applied to existing classes
10:22	rhickey	can be partially inplemented
10:23	rhickey	can mixin implementations mechanically
10:23	cemerick	The a-ha moment is surely just around the bend for me.
10:23	rhickey	reified
10:23	rhickey	looks like I can do pre and post conditions at the protocol level too
10:23	chouser	I see one patch and recall zero other requests in the last 6 months. I guess I'm not shocked, but a bit surprised.
10:24	rhickey	chouser: yeah, seems like as always, some people use download, others master/trunk
10:24	rhickey	of course, if there were more releases with bigger/breaking changes there might be more interest in bugfixes on a release branch
10:24	ol3	how do i define a 'private' value (e.g. like defn-)
10:24	cemerick	too much fantastic stuff keeps going into HEAD
10:25	cemerick	that's the sort of dynamic that makes the python moratorium seem like absolute lunacy to me.
10:25	chouser	apparently 1.0 is good enough without fixes for anyone that doesn't want HEAD
10:26	chouser	ol3: there's stuff in clojure.contrib.def or you can just (def #^{:private true} foo)
10:26	ol3	chouser: thank you
10:27	chouser	rhickey: pre/post for any method?
10:27	rhickey	so, we need names for the protocol predicate equivalents instanceof and isAssignableFrom
10:27	rhickey	chouser: yeah
10:28	chouser	oh, and in defprotocol rather than in implement? very nice.
10:28	rhickey	I went with extend for (extend atype aprotocol ...)
10:28	rhickey	so maybe (extends? aprotocol atype)
10:28	rhickey	and (implements? aprotocol aninstance)
10:29	chouser	I like 'extends?' -- points to types not instance for me.
10:30	rhickey	satisfies? an option instead of implements?
10:30	rhickey	for instance case
10:30	AWizzArd	hmm
10:30	chouser	'isa?' retains a moment of doubt for me, while 'instance?' is clear.
10:31	defn`	Am I being stupid? (defn myfunction [n] (reduce + (range 1 n)))
10:31	opqdonut	isa? pci? usb?
10:31	opqdonut	:)
10:31	defn`	oh god -- it's too early
10:31	defn`	nvm
10:33	rhickey	so, for instances: satisfies?, implements? something-else?
10:34	chouser	"implements" in Java is about classes on both sides
10:34	fogus_	rhickey: typeof? ?
10:35	chouser	it's too bad "instance" is inaccurate
10:35	esj	quacks_like?
10:35	chouser	heh
10:35	somnium	handles? ?
10:36	mtm_	follows? (as in follows the protocol)
10:37	chouser	(def a-foo (Foo)) (type a-foo) ==> ::Foo
10:37	djork	hmm, my boss is on the phone with assembla for some kind of pitch
10:37	defn`	Hmmm, how to calculate the number of divisors...
10:37	defn`	The efficient way, that is..
10:38	chouser	the instance case will mean the same as #(extends? %1 (type %2)) right?
10:39	Chousuke	how about "understands?"
10:40	ordnungswidrig	defn`: efficient would be using prime factors.
10:40	ordnungswidrig	Chousuke: adheres?
10:41	chouser	"provides?"
10:41	rhickey	chouser: it's slightly trickier than that, because sometimes a type is a Class, and thus a path to supers, and someting a keyword :my.ns/MyType, and not. extends? answers the question, "has someone said (extends MyType AProtcol ...)?", not, "does an instance of MyType satisfy the protocol?" (since they could due to class-based implementation)
10:42	rhickey	getting an answer to the second question requires an instance right now
10:47	chouser	that is certianly trickier.
10:49	rhickey	the instance one is more important
10:50	rhickey	compare instance? usage with .isAssignableFrom (never wrapped)
10:51	chouser	(instance? X a) implies (.x-method a) will work. (satisfies? ::X a) will imply (x-fn a) will work?
10:52	rhickey	chouser: where X is a protocol?, yes
10:53	chouser	oh, we don't use keywords for naming protocols? (skimming the Protocols page again...)
10:54	rhickey	subject to dynamic redefs - I've made it tolerant so that if you originally defprotocol P with foo and bar methods, extend some types to implement it, then redef P with baz, those impls will still work for foo and ba, but fail for baz calls, until you re-extend
10:54	chouser	ah, I see.
10:54	rhickey	protocols get top-level var names, so just Protocol
10:55	rhickey	detypes get keyword names, since var name is factory fn
10:55	rhickey	deftypes
10:55	chouser	but the dynamic redef issue there is separate from your earlier statement about trickiness that I'm still trying to grok.
10:56	rhickey	given some keyword ::MyType, there isn't a path to the implementing class, and thus its supers
10:58	chouser	(satisfies? Number 5) will be false because Number is a class not a protocol?
10:58	rhickey	so if you said (deftype Type [a b c] [Interface] ...) (extend Protocol Interface) then (extends? Protocol ::Type) -> false
10:59	rhickey	satisfies?/extends?/implements? etc are only about protocols as first arg, not intertwined with type system
10:59	chouser	so my example is either false or it throws something?
11:00	rhickey	oops, sorry (extend Interface Protocol ...) above
11:00	rhickey	chouser: throws something
11:00	rhickey	or nil
11:01	rhickey	I really want a separate set of predicates, and to encourage the use of protocols, it can completely isolate you from the host class system
11:02	chouser	that'll be important, so I'm on board. Just have to cut these new neural pathways...
11:03	rhickey	I guess satisfies? is better than implements?
11:05	rhickey	follows?, supports?, conforms?, complies?, heeds?, obeys?, observes?
11:06	fogus_	panders? caters? fits-the-bill?
11:06	rhickey	pander? hah
11:07	defn`	accommodates? harmonizes? integrates? suits?
11:08	fogus_	(head explodes)
11:08	Maddas	tries-really-hard?
11:08	chouser	fogus_: Mine's already in shambles, trying to pick up the pieces.
11:09	fogus_	,(head explodes)
11:09	clojurebot	java.lang.Exception: Unable to resolve symbol: head in this context
11:09	fogus_	:p
11:09	the-kenny	,(explode :head)
11:09	clojurebot	java.lang.Exception: Unable to resolve symbol: explode in this context
11:09	the-kenny	:(
11:11	mtm	ixnay on 'observes?' Sounds too much like an event watcher
11:11	osaunders	Is there such a thing as a lisp where code is written as a tree instead of lists?
11:11	chouser	,(isa? ::head ::exploded)
11:11	clojurebot	true
11:12	chouser	osaunders: lists are used to build trees
11:12	Chousuke	osaunders: there's misc which uses maps
11:12	ordnungswidrig	hmmm, can I determine the arity of a function at runtime?
11:12	chouser	osaunders: you can think of each list as a node, each element can be a symbol (leaf) or another list (child tree)
11:13	fogus_	richhickey: IMHO satisfies? is the most self-evident (so far)
11:13	fogus_	whoops, this is not github
11:14	osaunders	chouser: There's a difference though. Tree nodes may contain other tree nodes but that's not the same as child nodes.
11:15	Chousuke	but a tree which has a tree as a node is is in effect a bigger tree :P
11:15	osaunders	The difference is nested lists are a fixed structure but a tree makes up something more akin to a graph.
11:15	AWizzArd	I am not a native speaker, but maybe complies? is also ok?
11:16	ordnungswidrig	AWizzArd: "complies to", it is?
11:16	AWizzArd	genügt?
11:16	AWizzArd	for example
11:17	osaunders	Anyway I think I got my answer: no.
11:17	Chousuke	AWizzArd: you conform to a protocol, but comply with standards :)
11:17	ordnungswidrig	Chousuke: the point goes to you.
11:18	ordnungswidrig	complies-with? would by, um, long
11:21	fogus_	,(:arglists (meta (var +)))
11:21	clojurebot	([] [x] [x y] [x y & more])
11:21	fogus_	ordnungswidrig: ^^^
11:22	ordnungswidrig	fogus_: thanks, that is what I was looking for
11:23	chouser	,(:arglists (meta (var defmulti))) ; beware
11:23	clojurebot	([name docstring? attr-map? dispatch-fn & options])
11:24	Chousuke	ordnungswidrig: you can't trust arglists :)
11:25	Chousuke	(alter-meta! #'+ assoc :arglists '(chousuke was here))
11:25	Chousuke	,(alter-meta! #'+ assoc :arglists '(chousuke was here))
11:25	clojurebot	{:ns #<Namespace clojure.core>, :name +, :file "clojure/core.clj", :line 654, :arglists (chousuke was here), :inline-arities #{2}, :inline #<core$fn__4440 clojure.core$fn__4440@b374f9>, :doc "Returns the sum of nums. (+) returns 0."}
11:25	Chousuke	(doc +)
11:25	clojurebot	"(chousuke was here); Returns the sum of nums. (+) returns 0."
11:26	ordnungswidrig	Chousuke: I trust them on the repl for debugging. I don't expect them to be manipulated.
11:26	ordnungswidrig	:-)
11:26	Chousuke	ordnungswidrig: some Clojure arglists are, though.
11:26	Chousuke	like defmulti's
11:27	ordnungswidrig	Chousuke: I mangle with some higher order functions and I got lost on what the arity of some composition of them was.
11:27	ordnungswidrig	Chousuke: so this helps me to check that I think correctly
11:27	Chousuke	also anonymous functions don't have the metadata.
11:27	Chousuke	anyway
11:27	ordnungswidrig	Chousuke: hmm
11:27	Chousuke	chouser: didn't you have some code that uses reflection to figure out the arity?
11:27	ordnungswidrig	Chousuke: I see
11:28	chouser	yeah, I didn't write it, but I've posted it
11:28	ordnungswidrig	chouser: say, I "found" it?
11:28	Chousuke	is there some factoid for it?
11:30	ordnungswidrig	Is a (defn foo [r] ((comp a b) r)) equivalent to (def foo (comp a b)) ?
11:31	chouser	clojurebot: count arities?
11:31	clojurebot	Huh?
11:31	Chousuke	ordnungswidrig: yes and no.
11:31	ordnungswidrig	Chousuke: besides docs, meta information and such
11:31	chouser	clojurebot: count arities is<reply>To count arities see http://groups.google.com/group/clojure/msg/fb9930ba2a25d2dd
11:31	Chousuke	ordnungswidrig: then yes
11:31	chouser	clojurebot: count arities?
11:32	chouser	did I kill him?
11:32	Chousuke	except the latter will also accept more than one argument if the composition supports it.
11:32	Chousuke	clojurebot: ping
11:32	Chousuke	hm.
11:32	chouser	ordnungswidrig: anyway, there's a link to another approach to getting the arities of a fn.
11:33	clojurebot	Titim gan éirí ort.
11:33	clojurebot	PONG!
11:33	Chousuke	It's alive!
11:33	fogus_	ordnungswidrig: Even with reflection you're still bound by implementation details.
11:33	chouser	clojurebot: count arities?
11:33	clojurebot	No entiendo
11:34	Chousuke	I think you needed to add some spaces between the is and the <reply>
11:34	Chousuke	:P
11:34	chouser	ah
11:34	ordnungswidrig	fogus_: I know, I just wanted to make sure a higher-order-function-result would accept the number of arguments I tought.
11:34	chouser	clojurebot: count arities is http://groups.google.com/group/clojure/msg/fb9930ba2a25d2dd
11:34	clojurebot	Roger.
11:47	blackdog`	chouser: where is the source of clojurebot?
11:48	chouser	clojurebot: where are you?
11:48	clojurebot	http://github.com/hiredman/clojurebot/tree/master
11:48	blackdog`	ha :) fantastic
12:02	maacl	java.util.concurrent Executors expects a Runnable How do I pass it a Clojure function that takes a parameter? it works fine passing a function name but if I pass it a function including a param like (foo "bar") it breaks.
12:04	chouser	try #(foo "bar")
12:07	maacl	chouser: thanks :-)
13:49	cemerick	anyone care to share experiences with swarmiji?
13:50	rhickey	what to call the protocol implementation method map? these can be obtained explicitly, and can be used as mixins. Basically a map of :methodname -> fn
13:51	cemerick	It looks like a really pleasant alternative to JMS + couch (our current setup) w.r.t. the programming model, but (unless I'm missing something) a lot of the coordination lands on you, rather than the messaging container.
13:54	chouser	"method map" isn't too overloaded
13:55	technomancy	swarmiji struck me as pretty simplistic. you could probably build your own implementation in the time it would take to adapt your app to it.
13:56	technomancy	it's up to you to ensure that jobs actually finish, etc.
13:56	cemerick	yeah, that was my point w.r.t. coordination
13:56	cemerick	glad I'm not totally off the mark
13:56	dysinger	swarmiji just like ruby nanite is fire and forget
13:57	dysinger	doesn't provide for tracking work
13:57	technomancy	also the coding style drove me nuts when I was reading through it, but I'm really OCD about that kind of thing.
13:57	cemerick	I'm not particularly looking to migrate at all -- just making sure I'm not missing opportunities. JMS works like a champ, but isn't super-friendly on the clojure side of things
13:57	rhickey	chouser: needs to connect to things like (find-protocol-method-map p x)
13:58	dysinger	cemerick: I am working on this problem actively for our needs.
13:59	cemerick	dysinger: I'm particularly interested in hornetq, and its claims of providing a pure REST api shortly. That would make for a pretty easy way to switch between in-house deployments and something like SQS.
13:59	dysinger	I think we'll see more and more distributed compute tools around clojure shortly
13:59	cemerick	I know rhickey has thought some about abstract queue interfaces, but he's busy :-)
13:59	dysinger	I got managed jvms w/ erlang messaging going last night.
13:59	dysinger	but that's not my focus - just playing around.
13:59	rhickey	jinterface?
14:00	dysinger	y
14:01	dysinger	erlang starts jvm and monitors it / restarts it if needed. jvm uses erlang messaging via jinterface. jvm clients use jinterface to talk to distributed erlang managed jvms.
14:01	dysinger	service is .... repl !
14:01	rhickey	I always wanted to fiddle with that
14:01	dysinger	I love that you don't have to classify services - the service is repl.
14:07	cemerick	jinterface is tantalizing, but I've no interest in getting into erlang at all (hands are plenty full otherwise). It's a thought for the future though, esp. since we're using couch anyway.
14:55	rhickey	protocols are up! http://github.com/richhickey/clojure/commit/766b248f7d097c2c62e809ef6de2e6afd3850fc9
14:55	rhickey	feedback welcome
14:58	chouser	whee!
15:00	headius	dysinger: SuperTaz on #jruby wants to talk about your job req
15:14	tomoj	is contains? O(log_32 n) for sets?
15:15	Chousuke	hm.
15:15	Chousuke	(doc contains?)
15:15	clojurebot	"([coll key]); Returns true if key is present in the given collection, otherwise returns false. Note that for numerically indexed collections like vectors and Java arrays, this tests if the numeric key is within the range of indexes. 'contains?' operates constant or logarithmic time; it will not perform a linear search for a value. See also 'some'."
15:15	Chousuke	so, probably :P
15:16	chouser	tomoj: log32 for hash-sets, log2 for sorted sets. I think.
15:17	ordnungswidrig	why doesnt this work: (#({:a %}) :foo) whereas ((fn [x] { :a x }) :foo) does?
15:17	chouser	#(x) is (fn [] (x)) not (fn [] x)
15:18	ordnungswidrig	chouser: uh
15:18	chouser	not enough? :-)
15:18	ordnungswidrig	chouser: ah
15:18	the-kenny	What's the purpose of defprotocol? I see all these nice commits, but there are no use-cases and such things... That's what I'm missing
15:18	ordnungswidrig	chouser: how would I then generate a map?
15:19	Chousuke	the-kenny: They're for interfaces.
15:19	chouser	ordnungswidrig: #(hash-map :a %) or (fn [x] {:a x})
15:19	Chousuke	the-kenny: only, they're more powerful than java interfaces :)
15:19	ordnungswidrig	chouser: I see
15:20	Chousuke	the-kenny: but I think having a "native" construct for specifying interfaces is valuable. Reduces dependency on java.
15:20	Chousuke	I mean, even if defprotocol had no other use.
15:20	Chousuke	which it likely does :P
15:21	ordnungswidrig	Chousuke: does have or does not?!
15:21	Chousuke	does have
15:22	ordnungswidrig	Chousuke: for example?
15:23	chouser	ordnungswidrig: you've seen the assembla page?
15:24	ordnungswidrig	chouser: nope
15:25	chouser	ordnungswidrig: http://www.assembla.com/wiki/show/clojure/Protocols
15:26	ordnungswidrig	chouser: fun stuff
15:30	chouser	rhickey: does reify not accept a list of interfaces?
15:31	chouser	oh, nm, arg order changed
15:32	rhickey	sorry about that, yes, since no longer 'new', name can go first
15:33	chouser	yep, np.
15:33	chouser	thanks for the comment in Compiler.java. :-)
15:35	hiredman	"just realized that the current system I have is fatally flawed"
15:35	hiredman	poor fnparse :(
15:36	rhickey	reify docs here: http://www.assembla.com/wiki/show/clojure/Datatypes
15:45	chouser	could reify be faster than the old newnew?
15:47	chouser	it appears to be.
15:49	ordnungswidrig	is there a idiom for (if (fn? a) (a) a)
15:50	hiredman	trampoline
15:50	hiredman	maybe?
15:51	ordnungswidrig	a is either a function or a value
15:51	hiredman	,(trampoline (fn [] :a))
15:51	clojurebot	:a
15:51	hiredman	,(trampoline :a)
15:51	clojurebot	java.lang.IllegalArgumentException: Wrong number of args passed to keyword: :a
15:51	hiredman	:(
15:51	hiredman	,(trampoline identity (fn [] :a))
15:51	clojurebot	:a
15:51	hiredman	,(trampoline identity :a)
15:51	clojurebot	:a
15:51	hiredman	:D
15:52	tomoj	,(trampoline identity (fn [] (fn [] :b)))
15:52	clojurebot	:b
15:52	hiredman	yeah, well, …
15:52	ordnungswidrig	hiredman: now with (fn [x] :b)
15:53	ordnungswidrig	hiredman: doesnt look more idiomatic then (if (fn? a) (a) a) to me
15:53	tomoj	(if (fn? a) (a) a) seems perfectly fine to me
15:53	tomoj	couldn't imagine a clearer way to write it
15:53	ordnungswidrig	tomoj: so im my case it'd be (fn [a x] (if (fn? a) (a x) a))
15:53	ordnungswidrig	tomoj: looks good
15:54	tomoj	except, hmm
15:54	tomoj	,(fn? :a)
15:54	clojurebot	false
15:54	tomoj	,(fn? {})
15:54	clojurebot	false
15:55	tomoj	dunno if you want those
15:55	ordnungswidrig	,(ifn? {})
15:55	clojurebot	true
15:55	ordnungswidrig	,(ifn? :a)
15:55	clojurebot	true
15:55	tomoj	aha
15:55	ordnungswidrig	tomoj: but sure :-)
15:55	tomoj	guess fn? is better anyway, otherwise you wont be able to pass keywords, maps, etc as values
15:57	ordnungswidrig	tomoj: oh. I didn't think of this. This explains a weird error I'm chasing for days... doh
15:58	hiredman	http://gwolf.org/blog/piespy-modelling-irc-interactions <-- I smell a new clojurebot feature
15:58	tomoj	if I use nailgun can I use clojure as a scripting language? like, executable .clj files? that sounds nice..
15:58	ordnungswidrig	tomoj: btw, you're from austin?
15:58	tomoj	ordnungswidrig: yup
15:59	hiredman	#! is setup as a comment just for that purpose
15:59	ordnungswidrig	tomoj: how is car2go going? I'm from Ulm and I worked as a contractor for Daimler/TSS in Ulm who built the um fine peace of software for that :)
16:00	tomoj	ordnungswidrig: never heard of it till now
16:00	tomoj	but hmm.. I don't have a car, and I've always wanted a smart car
16:01	ordnungswidrig	tomoj: oh man, they failed on marketing this one
16:01	ordnungswidrig	tomoj: you don't want a smart :) At last not the ones they provide in Ulm. But the concept is great!
16:02	tomoj	trying to discover whether there are any locations near campus, and failing
16:03	ordnungswidrig	tomoj: unless you are a registered driver they do not provide many information. Usability could be done better on the website.
16:04	ordnungswidrig	tomoj: there is no map on the website?
16:05	tomoj	couldn't find one, anyway
16:05	tomoj	maybe I'm just dumb
16:05	tomoj	oh, now I found it :)
16:05	ordnungswidrig	tomoj: then you're smarter than me!
16:06	chouser	ah, nm -- I was misreading my notes. reify is the same speed as old new new
16:06	tomoj	looks like they're all downtown, far enough away that I'd have to ride the bus to get to them :(
16:08	ordnungswidrig	tomoj: in ulm the area is ok. in fact ulm is like twin town, neu-ulm on the other side of the river. and at first neu-ulm was out of area.
16:51	hiredman	clojurebot: latex \sum_{n=1}^\infty 2^{-n}
16:57	cemerick	hiredman: that's sick :-D
16:58	mikehogye	is there a way to get clojure.main to run a script from a file that is not on the classpath?
16:58	mikehogye	"java -cp clojure.jar -h" indicates that "path" can be a file or resource
16:58	rhickey	so, who's tried protocols?
16:59	chouser	rhickey: started. got distracted. :-/
16:59	mikehogye	but I keep getting "Could not locate blah__init.class or blah.clj on classpath"
16:59	rhickey	I'm finding their dynamic nature to be a lot of fun
17:00	cemerick	I'm always ~5 days behind :-P
17:01	rhickey	when backed with :on interface, speed as good as using the interface directly, so not really a tradeoff to write to protocols
17:01	mikehogye	hmm ... apparently I'm doing something else dumb -- a simple test case works fine
17:01	rhickey	and their dynamic lookup much much faster than multimethods
17:02	cemerick	rhickey: I actually just thought of a use case, so maybe I'll be of some use after all.
17:02	rhickey	cemerick: cool
17:03	cemerick	rhickey: BTW, are you planning on having good and proper name support in deftype, etc., by the time new is merged into master?
17:03	rhickey	cemerick: good and proper?
17:03	cemerick	dashed-name, etc
17:04	rhickey	I've been thinking about that, I'd hare for people to be marrying the munging algorithm on the Java side, but there might not be a Java side...
17:04	Chousuke	hiredman: what's with the near-illegible colour though? :/
17:04	rhickey	I'd hate for
17:04	cemerick	it's obviously window-dressing, but it's just odd to see camelCased keywords
17:05	hiredman	Chousuke: it's fixed
17:05	hiredman	that was just the color in the example I was following
17:05	cemerick	rhickey: I'd say, if you're using non-Java names, that a decision you need to live with the consequences of
17:05	cemerick	nothing stopping people from using Java names if interop is a priority for them.
17:06	rhickey	cemerick: but then I need to document and fix the munging scheme
17:06	rhickey	so far there are no human consumers of the munging, so it can be quite verbose and ugly
17:06	cemerick	rhickey: well, that's a cost that only you can evaluate at this point. I don't know that you need to make it pretty, though.
17:07	cemerick	e.g. if you're putting dashed-names etc. in your deftype slots, I wouldn't expect them to be usable from Java at all anyway
17:07	rhickey	what if it was limited to dash-becomes_underscore?
17:07	mikehogye	never mind; found my problem
17:08	cemerick	as opposed to supporting all of the naming possibilities like embedded:colons, etc?
17:08	rhickey	yeah
17:09	cemerick	I think that's a fine compromise. Long term, though, I'd assume you'd like to keep allowable names, etc., totally independent of host restrictions. i.e. if you need to have a host-friendly name, stick to underscores, or target one host explicitly.
17:10	Chousuke	maybe an option somewhere to specify a "host name"? :/
17:10	rhickey	what's the url syntax for line#s in github source view?
17:10	chouser	you can click on a line
17:10	chouser	I think it's #L012
17:10	rhickey	http://github.com/richhickey/clojure/blob/master/src/jvm/clojure/lang/Compiler.java#L2487
17:11	cemerick	I'm guessing the biggest difficulty will be encountered by anyone creating macros and such on top of deftype/defclass.
17:11	cemerick	rhickey: oh, see, I think that's totally sane as-is
17:11	Chousuke	I suppose it would complicate things much if the thing has two names, one on the clojure side and another on the host side.
17:12	_ato	think most people are used to that munging from stack traces
17:12	cemerick	i.e. no need to clean it up AFAIC
17:13	cemerick	Chousuke: I think something like that will be necessary eventually. Who knows what'll happen when the objc host backend is built? :-P
17:15	drewr	you can click on the line number in the margin too
17:19	_ato	http://kenai.com/projects/jruby/pages/CompilerNameMangling
17:19	_ato	thye have less cases though
17:22	raek	so, if I want to try protocols, where should I begin?
17:22	raek	or rather, what kind of stuff can I use it for?
17:37	headius	rhickey: it would be nice if we could start to agree on mangling conventions
17:37	headius	I've brought this up with scala guys, but they apparently don't have any standard even now
17:38	hoeck1	raek: I would start with reading http://www.assembla.com/wiki/show/clojure/Protocols
17:39	hoeck1	raek: in fact, I did, but its too late here right now, so I'm going to try them out tomorrow
17:45	tomoj	what is this ":on barMethod" thing?
17:45	tomoj	seems unexplained
17:46	hiredman	uh
17:46	hiredman	its :on AnInterface isn't it?
17:46	hiredman	you can implement a protocol on an interface
17:46	hiredman	well
17:46	hiredman	define, not implement
17:47	krumholt_	I read the article about protocols . can someone explain to me in 1 or 2 sentences what kind of problem protocols address?
17:47	tomoj	there is also a ":on barMethod" in the example
17:48	chouser	rhickey: deftype implements a interface but not a protocol, right?
17:49	hiredman	krumholt_: you can name a set of opertions on some thing
17:49	hiredman	a protocol for dealing with something
17:49	_ato	krumholt_: basically it's like multimethods dispatched on type, but multiple methods can be grouped together under the one name and it's performs much faster
17:50	Chousuke	krumholt_: consider the Clojure Seq abstraction.
17:50	krumholt_	so it's a nicer way to express common multimethod usecase
17:50	Chousuke	krumholt_: As far as I understand this stuff, that will become a protocol
17:50	_ato	krumholt_: sort of like a more dynamic version of javas interfaces
17:51	krumholt_	ok thanks everyone. i think i get the idea
17:51	hiredman	well, a protocol is a set of ops, and a multimethod is a single op
17:52	Chousuke	just to add to the mix, the design document also mentions multiprotocols :P
17:53	hiredman	I'm not too clear on extending protocols
17:53	_ato	tomoj: maybe :on barMethod lets you alias a java interface method to a clojure function name or something
17:54	hiredman	but I guess you just make a new protocol with the same set of ops?
17:54	chouser	_ato: I think that's right
17:56	_ato	"By default, methods of the protocol map to methods of the same name in the interface. A different mapping can be provided on a per-method basis using :on inside the signature."
17:56	_ato	^ from the defprotocol docstring
17:56	hiredman	hmmm
18:01	drewr	are there any pastes with a good protocol eg?
18:05	chouser	no return types on protocol methods?
18:06	chouser	no protocols on protocols?
18:07	chouser	I must not be thinking about this correctly.
18:07	chouser	oh -- no types on any of the args?
18:08	_ato	chouser: what would a protocol on a protocol do?
18:09	chouser	well -- maybe "on" is the wrong word. If something is a Car it will provide all the methods that a Vehicle does, plus some Car-specific ones.
18:10	the-kenny	hm... I think clojure-mode ignores (setq indent-tab-mode nil), strange.
18:10	chouser	So am I not supposed to capture that when I defprotocol, but just hope/assume that anything extending Car will also extend Vehicle?
18:11	Chousuke	chouser: I don't think you're supposed to have protocols for Cars and Vehicles :/
18:11	Chousuke	I mean, they should be split so that you could implement both with no overlap.
18:12	chouser	where does the "start" method go? One or the other? both?
18:12	chouser	bah. gotta go.
18:13	hiredman	if there is any question, it goes on the more specific
18:13	hiredman	or Vehicles->StartableVehicles->Cars
18:14	Chousuke	Movingthings - Motorised things - Wheely things
18:14	_ato	yeah, it's not inheritance
18:15	_ato	it's a "protocol"
18:15	_ato	eg you could start things that aren't vehicles
18:15	technomancy	the-kenny: it's not that clojure-mode ignores it; it's just that it becomes buffer-local when you set it
18:15	_mst	I remember looking at how Compojure implemented multiple backends for sessions (file, memory, database, ...) and thinking it could use something a bit like this
18:16	technomancy	the-kenny: (set-default 'indent-tabs-mode nil)
18:16	_mst	not really inheritence, just a way of expressing the required interface in code and making it possible/easy to provide custom implementations
18:16	the-kenny	technomancy: Oh, ok. I wasn't aware of that.
18:17	_ato	if I'm "getting it" right the idea is composition is better than extension
18:17	hiredman	well, you can implement protocols on interfaces which are heritable
18:17	_ato	hiredman: right, but I think that's only to support java interop
18:18	_ato	you're not supposed to use that to "get" inheritance
18:18	hiredman	interface inheritence is ok, implementation inheritence is bad
18:18	the-kenny	technomancy: hm.. that doesn't work.
18:19	technomancy	it might only take effect for new buffers?
18:19	the-kenny	I just restarted emacs
18:20	_ato	I think the key is to think of it more like duck-typing... who cares whether something is a car or a vehicle as long as it's "startable"
18:20	hiredman	if you look at the java side of clojure the tree is deep interfaces, shallow implementation sharing
18:21	hiredman	so you have a long chain of interfaces, and at the end maybe one abstract class with some common code and then a single concrete class
18:22	_ato	"#
18:22	_ato	*
18:23	_ato	# While avoiding some of the drawbacks implementing an interface creates an instanceof type relationship and hierarchy"
18:23	hiredman	shrug
18:24	_ato	I dunno maybe we just wait for Rich to give a talk on it and clear up what is good and proper :p
18:24	hiredman	I am not using clojure's code base as argument from authority, but as an example of what I think works well
18:25	hiredman	_ato: the fact remains, interfaces are heritable, and you can implement protocols :on interfaces
18:25	hiredman	bah
18:25	hiredman	s/implement/define/
18:27	_ato	yeah, I'm not necessarily disagreeing with you, just that's my interpretation of why Rich has apparently made protocols themselves not heritable
18:28	hiredman	~latex sum \limits_{k=1}^N k^2
18:28	hiredman	:(
18:29	hiredman	~latex \sum \limits_{k=1}^N k^2
18:30	the-kenny	Google Charts can do LaTeX? Wow
18:30	hiredman	_ato: I think inheritence matters less in clojure because clojure is dynamic and has first class functions
18:31	hiredman	so using inheritence for types is nixed, and you can mix in implementations via functions
18:32	krumholt_	when do i need :use and :import in the ns macro? is it correct that use is for clojure code and import for java code?
18:32	hiredman	yes
18:32	krumholt_	ok thanks
18:33	hiredman	http://github.com/hiredman/clojurebot/blob/master/hiredman/clojurebot/latex.clj#L1
18:34	qed	Could someone step me through something?
18:34	qed	I know that lazy-cons isn't the way to do this anymore, but:
18:34	qed	(def triangles (lazy-cons 0 (map + triangles (iterate inc 1))))
18:36	hiredman	I, uh, well using lazy-cons there would be silly even if it still existed
18:36	hiredman	you may as well (def triangles (cons (map + triangles (iterate inc 1))))
18:36	hiredman	er
18:37	hiredman	(def triangles (cons 0 (map + triangles (iterate inc 1))))
18:37	qed	that's chouser's code
18:37	hiredman	:(
18:37	qed	hiredman: could you explain to me how you might write that with lazy-cat?
18:37	qed	or a completely different problem, i just dont see how it works
18:38	hiredman	lazy-cat?
18:38	qed	nod
18:38	hiredman	(lazy-cat [0] (map ...))
18:39	hiredman	lazy-cat just concats sequences
18:39	qed	ps your code didn't work
18:39	_ato	(lazy-cat xs ys zs) === (concat (lazy-seq xs) (lazy-seq ys) (lazy-seq zs))
18:39	hiredman	so you give it sequences
18:39	qed	hiredman: but you can use it to create an infinite seq right?
18:39	hiredman	no
18:39	_ato	qed: maybe you want lazy-seq
18:39	hiredman	not lazy-cat
18:39	hiredman	qed: what do you mean didn't work?
18:40	qed	(def triangles (cons (map + triangles (iterate inc 1)))) blows up
18:40	hiredman	qed: please notice the correction I pasted right after
18:40	qed	oh d'oh, sorry
18:41	_ato	hiredman: that doesn't work either as triangles is unbound in the right-hand side
18:41	_ato	that's probably why chouser used lazy-cons
18:41	qed	lazy-seq is the new lazy-cons, right?
18:41	hiredman	no
18:42	qed	where did lazy-cons go?
18:42	_ato	(def triangles (lazy-seq (cons 0 (map + triangles (iterate inc 1)))))
18:42	_ato	http://clojure.org/lazy
18:42	qed	thanks _ato
18:43	_mst	also worth noting that that version necessarily hangs on to the head of the seq...
18:44	qed	(next triangles)
18:44	qed	oops
18:44	technomancy	nil
18:45	qed	technomancy: :)
18:45	qed	_ato: could you step me through what's happening in your function?
18:46	hiredman	(it's not a function)
18:46	qed	im aware, but surely you understand what im sasking
18:46	qed	asking*
18:46	somnium	is there any need to use lazy-seq with map?
18:46	_ato	qed: lazy-seq is a macro that doesn't execute it's body until first/rest is called on it
18:47	_ato	somnium: in this case yes, because triangles (as the map argument) doesn't exist yet
18:48	_ato	,(do (lazy-seq (println "hi")) nil)
18:48	clojurebot	nil
18:48	_ato	,(do (first (lazy-seq (println "hi"))) nil)
18:48	clojurebot	hi
18:49	hiredman	without looking at the code, I think you should collapse it into a call to interate
18:49	hiredman	iterate
18:49	hiredman	(iterate some-function 0) can surely get you the same result
18:50	_mst	maybe (iterate some-function [0 1]) since you need to track two pieces of state
18:50	hiredman	_mst: are you sure?
18:51	_mst	nope :)
18:51	hiredman	there are two sequences in the map, sure
18:51	_mst	but I have it in my head you need to track a running integer (from 1) and the last triangle number you saw
18:52	_mst	first attempt: (map first (iterate (fn [[t i]] [(+ t i) (inc i)]) [0 1]))
18:52	_ato	,(take 10 (map #(/ (* % (inc %)) 2) (iterate inc 0)))
18:52	clojurebot	(0 1 3 6 10 15 21 28 36 45)
18:52	_mst	tricky :)
18:53	qed	nice :)
18:53	_ato	http://en.wikipedia.org/wiki/Triangular_number :-P
18:53	hiredman	(list (- (* n n) (* m m)) (* 2 m n) (+ (* n n) (* m m))
18:53	hiredman	I just don't remember what m and n are supposed to be
18:54	somnium	that one is pleasingly symmetrical somehow
18:54	hiredman	clojurebot: latex \frac{-1\pm\sqrt{8x+1}}{2}
18:57	hiredman	http://en.wikipedia.org/wiki/Pythagorean_triple
18:58	hiredman	it occurs to me I might confused as to which euler this is
19:01	qed	#12
19:02	qed	1 + 2 + 3 + 4 = 10, 10 is div by 1 2 5 and 10
19:03	qed	which triangle number has 500 divisors
19:03	qed	err > 500 div
19:04	qed	I started with (defn gen-tri-num [n] (reduce + (range 1 (+ n 1))))
19:05	qed	then i was going to calc the number of divisors for each tri-num i generated
19:05	qed	that's where i got stuck -- not sure the best way to do that
19:07	hiredman	http://gist.github.com/232449 one of the more amusing bits from my eulering
19:07	hiredman	I don't recall what made me call it totally useless
19:09	qed	maybe that it's incredibly useful?
19:10	hiredman	reverse psychology?
19:10	tomoj	I never got that one
19:11	tomoj	took way too long
19:11	qed	reverse psychology is even less rigorous than forward psychology
19:12	hiredman	clojurebot: reverse psychology is even less rigorous than forward psychology
19:12	clojurebot	In Ordnung
19:12	qed	:)
19:12	qed	clojurebot: reverse psychology
19:12	clojurebot	reverse psychology is even less rigorous than forward psychology
19:23	tomoj	damn your divisor function is SO much faster than mine
19:26	qed	ugh i just signed an NDA
19:26	qed	i kick myself everytime i do that
20:36	hiredman	clojurebot: hydra?
20:36	clojurebot	Excuse me?
20:41	penthief	I've just done clojure-install from emacs, and it worked, but after restarting I get 'symbol's value as variable is void "package-activated-list"' when I type M-x slime
21:24	chouser	rhickey: so I'm trying to redo finger trees with protocols
21:25	chouser	I implement a lot of clojure interfaces
21:25	chouser	does that mean (until clojure's interfaces are themselves protocols) that I need to create one protocol per interface
21:30	chouser	and instead of a reify on a couple interfaces, I need to extend a huge list of uninheriting protocols.
21:32	hiredman	I gtalk's sms gateway and appengine's xmpp support could get me a repl of sorts on my phone
21:33	hiredman	I think
21:33	tomoj	good luck typing sexp's on your phone
21:33	hiredman	:P
21:34	hiredman	I'm trying to think of something I can do with that
21:35	tomoj	hmm.. if you take paredit and navigation operations and separate them from self-insert stuff, I wonder how many operations you wind up with
21:37	rhickey	chouser: can you give me an example?
21:38	rhickey	I think while Clojure's abstractions are interfaces you can just implement them (in e.g. deftypes)
21:38	rhickey	if you introduce your own abstractions, you can do so with protocols
21:39	rhickey	no need to wrap Clojure's interfaces with protocols before Clojure does
21:39	rhickey	but what do you mean by uninheriting?
21:40	hiredman	protocols don't inherit
21:40	hiredman	I think, is what he means
21:45	djork	what is ->> and why is penumbra using it ?
21:45	hiredman	->> is newish
21:45	djork	hmm
21:45	djork	ok
21:45	hiredman	like -> but the other side
21:45	djork	like, the last few weeks?
21:45	hiredman	,(doc ->>)
21:45	clojurebot	"([x form] [x form & more]); Threads the expr through the forms. Inserts x as the last item in the first form, making a list of it if it is not a list already. If there are more forms, inserts the first form as the last item in second form, etc."
21:46	hiredman	djork: more like months I think
22:02	chouser	Ok, so I can use deftype to implement existing interfaces, and then extend it with my own protocols
22:02	dreish	Is there any good documentation for ns yet?
22:03	djork	hmm, I want to believe in penumbra :)
22:03	hiredman	(doc ns) seems to have all the bits
22:03	clojurebot	"([name & references]); Sets ns to the namespace named by name (unevaluated), creating it if needed. references can be zero or more of: (:refer-clojure ...) (:require ...) (:use ...) (:import ...) (:load ...) (:gen-class) with the syntax of refer-clojure/require/use/import/load/gen-class respectively, except the arguments are unevaluated and need not be quoted. (:gen-class ...), when supplied, defaults to :name correspo
22:03	dreish	Seriously? That's not even close to complete.
22:04	hiredman	dreish: what do you mean?
22:04	tomoj	hehe
22:04	hiredman	(doc use)
22:04	tomoj	all the bits are there, they're just scattered about and difficult (for me) to understand
22:04	clojurebot	"([& args]); Like 'require, but also refers to each lib's namespace using clojure.core/refer. Use :use in the ns macro in preference to calling this directly. 'use accepts additional options in libspecs: :exclude, :only, :rename. The arguments and semantics for :exclude, :only, and :rename are the same as those documented for clojure.core/refer."
22:04	djork	seems clear to me
22:04	tomoj	would be nice to have some examples of all the different ways to use all the subforms
22:04	dreish	What tomoj said. Which I guess isn't the same as being undocumented.
22:05	tomoj	someone had suggested before setting up examples of all the core functions
22:05	tomoj	wonder if anything came of that
22:05	dreish	I find myself using ns mainly by guess-and-fix because the docs are just a tangle of spaghetti.
22:05	djork	I think the docs just need a bit more hyperlinking.
22:05	tomoj	yes, guess-and-fix indeed :)
22:06	djork	I actually found it pretty helpful to just sit down and read the docs from the beginning. It's better than most languages.
22:07	dreish	Yeah, I generally don't work that way once I'm past the basics.
22:07	djork	maybe it's time for clojure.contrib.examples :)
22:07	djork	or cheat
22:08	dreish	Or just a thorough, third-party reference to the language.
22:08	djork	http://cheat.errtheblog.com/
22:08	djork	dreish: have you tried this yet? http://jnb.ociweb.com/jnb/jnbMar2009.html
22:08	djork	it's very good
22:09	dreish	djork: Thanks for the reminder. I've seen that, but forgot about it.
22:09	djork	how about cheat sheets for different areas of clojure
22:09	dreish	I vaguely remember some inaccuracies, I think, but that could have been a long time ago, or a different document.
22:10	dreish	Doesn't seem to cover ns, though.
22:11	dreish	What I'm wondering, specifically, is whether there's a way to include several libs at the top dot level without saying :use over and over.
22:12	dreish	I.e., to replace (:use [util]) (:use [server-lib]) (:use [clojure.contrib.def]), which seems pretty gross to me.
22:12	djork	what would you want to shorten, for example...
22:12	tomoj	(:use util server-lib clojure.contrib.def) doesn't work?
22:12	dreish	I don't think so. I thought it complained about no such thing as util.server-lib.
22:12	tomoj	single-segment names are bad, I think
22:13	dreish	Thanks, mom.
22:13	dreish	:-P
22:13	djork	single-segment names aren't just bad... they don't work in some cases (I believe)
22:14	nforrest	I've read that in clojure, list element access is O(n) and prepending to a list is O(1). I understand how that works (it's a linked list). However, I've also heard that vector element access is O(1) and appending to a vector is also O(1). What sort of data structure allows you to achieve that kind of performance?
22:14	djork	dresh, consult (doc require)
22:14	djork	it's big
22:14	dreish	I'm not into languages that tell me to sit up straight. Clojure hasn't seemed much like that to me so far.
22:14	tomoj	I'm imagining a webapp that automatically indexes all the interns in clojure.* and clojure.contrib.* and lets people submit examples, maybe with vote up/down
22:15	djork	nice idea
22:15	tomoj	why are single-segment names bad, again? I forget
22:16	arohner_	nforrest: it's not technically O(1), it's O(log sub 32)
22:16	tomoj	man "clojure" is so difficult to make punny names with :(
22:16	nforrest	Oh, I see.
22:16	tomoj	log_32 is practically constant, though
22:16	nforrest	That seems much more possible.
22:16	nforrest	Thanks.
22:16	arohner_	there are some blog posts somewhere about the clojure datastructures
22:17	dreish	tomoj: Apparently (:use util server-lib clojure.contrib.def) does work. I must have had an extra pair of something when I tried that. Thanks.
22:17	djork	what, clojure makes for awesome puns :)
22:17	tomoj	and then you can do like
22:17	djork	my toy mud is called "dunjeon"
22:17	tomoj	(:use [util :only (foo)] server-lib ...)
22:17	tomoj	hmm, yeah, hadn't thought about that kind of pun yet
22:18	tomoj	need to find a phonetic dictionary to search through for zh and soft g
22:18	djork	yeah just throw some j replacements in there and you're done
22:19	tomoj	:)
22:23	qed	what is a 'coll' in clojure?
22:23	qed	like any form of a list? can a seq be a coll?
22:24	qed	is a seq a coll?
22:24	tomoj	I think 'coll' means any x for which (sequential? x) is true
22:25	rhickey_	,(coll? (seq [1 2 3]))
22:25	clojurebot	true
22:25	qed	thanks rich, tomoj
22:25	tomoj	oh, hmm
22:26	tomoj	count's parameter is called "coll" in the docs but it works on non-persistent collections too
22:26	qed	rhickey_: is that the same rationale behind forcing the programmer to create (seq "abcd") before cons'ing on it?
22:26	qed	onto*
22:26	qed	like (cons 1 (seq "abcd"))
22:26	tomoj	oh, {} is not sequential
22:26	tomoj	but it is a coll
22:27	tomoj	what's the interface for seqables?
22:27	tomoj	and, is there a predicate for that?
22:27	rhickey_	Seqable
22:28	tomoj	I always thought sequential? checked for seqability
22:39	djork	maybe this falls under "premature optimization" but I am wondering about the performance implications of frequently calling conj or assoc on large vectors or maps
22:40	chouser	djork: it is premature. when you find you need it, look at transients
22:40	djork	those are new, aren't they?
22:41	chouser	newish
22:49	djork	wow the JVM exhibits a really wild range of performance
22:49	djork	79 ms, 30 ms, 2.6 ms
22:49	djork	not a cached lazy seq or anything
22:50	djork	starting from scratch with a ref of a vec of 100K strings
22:50	chouser	deftype can't implement a protocol, right?
22:54	rhickey_	chouser: nope
22:55	rhickey_	I've thought about supporting extends there, since why should interfaces get preference?
22:56	rhickey_	but it could get confusing, the difference between Java-like methods and real fns
22:56	chouser	so confused already
22:56	rhickey_	oh no!
22:56	chouser	I'm starting from http://tinyurl.com/ylx4j3k/finger_tree.clj#LID18
22:56	rhickey_	what's confusing?
22:56	chouser	a pile of interfaces
22:57	chouser	that starting point uses interfaces in a couple different ways, and I think converting to protocol/deftype is forcing me to tease apart the reasons.
22:59	chouser	Some of those interfaces, like IDigit mearly aggregate other interfaces. No way to do that with protocols, right?
22:59	djork	wow, clojure is a better Java :)
22:59	rhickey_	not so far, but doing that doesn't really save you much in the implementing
22:59	chouser	right
22:59	chouser	just a few words.
23:00	chouser	take none of this as criticism -- I don't understand well enough to complain yet.
23:00	rhickey_	and you can put multiple protocols in a single extend
23:00	chouser	:-)
23:00	chouser	right
23:00	chouser	ok, setting that aside.
23:02	chouser	IDoubleSeq does that but also adds a couple methods. So I should replace that with a defprotocol that leaves out the interfaces and just defines the two methods.
23:02	rhickey_	right, the real reason for aggregating protocols is to combine multiple dependent contracts, but that has some implementation issues
23:02	rhickey_	yes, best to think of the Clojure interfaces as interop, and your new abstractions with protocols
23:03	chouser	ok, so I think I'm ok on through IDeepTree. That extends IPersistentCollection for interop and defines three methods that are just accessors to data fields.
23:03	rhickey_	it will be really nice when you can interop with the Clojure abstractions through protocols
23:04	chouser	yes!
23:04	chouser	but I should understand this anyway.
23:04	chouser	I might have to explain it to someone.
23:04	chouser	in Chapter 10.
23:04	chouser	ok, because there are new data items, that will call for deftype
23:06	chouser	I can use deftype's IPersistentMap auto-impl to access them, so I don't need hand-written accessor methods for IDeepTree
23:06	rhickey_	right, most of your factory fns on newnew can become deftypes with factory fns
23:07	chouser	But I need to support IPersistentCollection, and since that's an interface not a protocol, those methods have to be defined inside the deftype
23:08	rhickey_	right, but some of your new stuff can share impls, like measureFns/More/Pop betwen empty/single
23:08	rhickey_	mixins are really easy with protocols
23:08	rhickey_	and clean, no incidental hierarchy
23:09	chouser	just merge maps as needed, right?
23:09	rhickey_	yeah
23:09	rhickey_	extend is an ordinary fn
23:09	rhickey_	and the method maps just kw->fn
23:10	chouser	ok, but I'll have some DeepTree methods that must be in deftype (for IPersistentCollection) and others in extend for my own protocol stuff.
23:10	rhickey_	you can reuse an impl wholesale, just (extend type proto map)
23:10	rhickey_	yes, having methods not 'in' will be commonplace with protocols
23:11	rhickey_	but at least will be sets, vs independent multimethods
23:12	chouser	it just seems odd that some methods must be in deftype while others can't be.
23:12	rhickey_	in a pure Clojure design the deftypes might have no methods at all
23:12	chouser	right, that makes sense to me.
23:12	hiredman	excellent
23:12	rhickey_	so, the methods there are just interop
23:12	chouser	I guess it's the interop nature that's forcing some of the methods into deftype.
23:13	rhickey_	one problem is the use of the word method, since they are methods in very different senses, and the Java ones are not first-class
23:13	chouser	the methods in extend will be able to use the deftype :kw accessors, and call the deftype methods
23:13	rhickey_	maybe we should use another term for protocol fns
23:14	rhickey_	chouser: kw accessors yes, methods will need (.foo x)
23:14	hiredman	operations
23:14	rhickey_	although that's the case inside deftype too, no real class scope for methods
23:14	rhickey_	hiredman: maybe
23:15	chouser	the methods in deftype will be able to call any protocol methods via the defprotocol-created functions
23:15	chouser	and of course access their own fields.
23:15	rhickey_	chouser: sure
23:15	chouser	ok.
23:15	chouser	thanks for walking me through that. I think I'm back on top of it again.
23:15	rhickey_	but the point of making (:kw x) as fast as dot was so that protocol methods are not at a disadvantage
23:16	rhickey_	chouser: cool
23:16	chouser	it reminds me so much of math -- makes sense until you try to do the homework.
23:17	rhickey_	hah
23:17	chouser	once you can do it on your own then you know you've got.
23:17	chouser	got it.
23:17	rhickey_	well, converting something is hard too, since you've already got one mental model
23:18	rhickey_	on a green field design deftype + protocols should be sweet
23:18	chouser	and the interop here is perhaps deeper than will be common
23:19	chouser	will I have a problem getting the default IPersistentMap methods in my deftype that also implements custom IPersistentCollection methods?
23:19	rhickey_	it will be straightforward to make protocols that correspond to (and are :on) the existing interfaces
23:19	rhickey_	chouser: yes
23:20	rhickey_	there isn't a way to pick and choose bits of the impl, as it can be difficult to determine what will work together
23:20	rhickey_	so, either I do it or you do
23:20	rhickey_	but not some of each
23:21	rhickey_	but you've already done it
23:21	rhickey_	just add some dots
23:23	rhickey_	gotta crash - good luck!
23:23	chouser	so my deftype for IDeepTree needs to include accessor methods
23:23	chouser	like I have now
23:24	rhickey_	if you don't take the IPersistentMap impl, you'll still get keyword accessors
23:24	chouser	well, I
23:25	chouser	well, I'll let you sleep. I probably won't get that far tonight anyway.
23:25	chouser	thanks again.
23:25	rhickey_	tomorrow then...
23:26	tomoj	this deftype/protocol stuff is still a total mystery to me
23:26	hiredman	so :on is something of a red herring
23:28	chouser	well, it allows you to bridge existing interfaces into the defprotocol/extend system
23:28	chouser	but yeah, I guess it's an interop feature on an other native construct.
23:28	hiredman	sure, but it sounds like the idea is that for existing interfaces you will just use deftype directly
23:31	chouser	oh, I see what you're saying
23:32	chouser	instead of putting some methods into the deftype I ought to be able to make a bridge protocol for IPersistentCollection and implement them with 'extend' like all my other methods.
23:33	chouser	except
23:33	chouser	no, that should be right.
23:40	chouser	except not in this case, because the whole point is to let people do (count my-finger-tree), but 'count' is not yet a protocol method -- it wants to call .count on an actual IPersistentCollection object, so having my own kind of thing that uses defprotocol/extend won't help.
23:40	chouser	it needs to be an actual intance of a Java class that extends IPersistentCollection, so I need to have those methods in the deftype.
23:47	hiredman	I haven't looked at my reader in a few weeks, maybe I should update it
23:53	tomoj	what's a good way to make your code configurable?
23:53	tomoj	without making people need to wrap everything in a binding
23:54	hiredman	pass an argument
23:54	tomoj	ah, yes
23:54	tomoj	hmm
23:55	tomoj	I guess that would mean I'd have to wrap all my tests inside a macro or something
23:55	hiredman	usually the first thing I do with a binding heavy api is start wrapping stuff in (defn foo [some-resource args] (binding [resource some-resource] ...))
23:55	tomoj	or pass the same parameter over and over again
23:56	tomoj	I'm working on htmlunit tests with clojure.test and want to set a global root-url