#clojure – 2009-07-09

2009-07-09

01:43	sayyestolife	hm
01:44	sayyestolife	I might have missed something; but wouldn't it be nice of the api doc had some concrete examples?
02:04	arbscht_	sayyestolife: have a look at http://clj-doc.s3.amazonaws.com/tmp/doc-1116/index.html
02:04	arbscht_	oops, I meant http://java.ociweb.com/mark/clojure/article.html
02:05	arbscht_	but yes, it would be nice if the api doc had examples :)
02:07	arbscht_	ah, this has progressed somewhat too: http://en.wikibooks.org/wiki/Clojure_Programming/Examples/API_Examples
02:09	sayyestolife	thanks
03:14	sayyestolife	hmm in python and c++ (and in other languages aswell) you can specify a default value for function parameters; is there a way to do this in clojure too?
03:15	sayyestolife	like "void func(int x=0) { return x; }"
03:16	hoeck	sayyestolife: sometimes I'm using arity overloading to specify default arguments
03:16	arbscht_	not in the params vector, but you can rebind with (let [x (or x 0) ..] ..) in the function body
03:16	hiredman	arity or hash destructuring
03:16	sayyestolife	hmm, no thanks then; that is too much work for something so simple :)
03:17	hiredman	shrug
03:18	hiredman	,((fn this ([a] (this a 1)) ([a b] (+ a b))) 3)
03:18	clojurebot	4
03:19	Riecon	pretty much the same way they do it in java right?
03:22	hiredman	,((fn [{:keys [a] :or {a 1}}] a) {:a 2})
03:22	clojurebot	2
03:22	hiredman	,((fn [{:keys [a] :or {a 1}}] a) {:b 2})
03:22	clojurebot	1
03:23	hiredman	except people don't use much hash destructuring it seems
03:23	hiredman	:(
03:44	Riecon	I donno, I'm a fan :)
03:44	Riecon	although I use it in lets alot
05:46	sayyestolife	hm
05:47	sayyestolife	If I want to pass an argument when I create a java class instance, how do I do that? I tried (new MyClass arg), but it didn't work
05:55	sayyestolife	eh, found the error
05:55	sayyestolife	how does one reload an opened file?
06:04	sayyestolife	ehm
06:04	sayyestolife	isn't is possible to add a directory on the classpath?
06:16	ceninan	sayyestolife: don't know if java supports dir in classpath, but either way a shell script could do it
06:18	Raynes	sayyestolife: java -cp <dir>/
06:20	eevar	someone able to help me speed up http://pastebin.com/d64ca3d98 ?
06:40	sayyestolife	anyone here used clojure-mode in emacs?
06:41	arbscht_	I use it
06:42	sayyestolife	How do I make it start automatically when editing .clj files?
06:44	eevar	(add-to-list 'load-path "/path/to/clojure-mode") (require 'clojure-mode) ;; in your .emacs should do?
06:45	sayyestolife	eevar I still have to do a M-x clojure-mode each time I open a new file
06:46	asbjxrn	(setq auto-mode-alist
06:46	asbjxrn	(cons '("\\.clj$" . clojure-mode)
06:46	asbjxrn	auto-mode-alist))
06:48	sayyestolife	nice, thanks
06:48	sayyestolife	one more thing though; how do I make the connection between emacs and the clojure program?
06:48	sayyestolife	(the interpreter)
06:49	asbjxrn	eevar: Add a type hint for the image var in the render-frame function.
06:49	eevar	you'll need swank-clojure and slime, if I understand your question correctly
06:49	eevar	asbjxrn: how? :)
06:50	ceninan	any reason why "(do (print "Enter something: ") (read-line))" waits for the input before printing?
06:50	sayyestolife	hmm okay, what I meant was that I'd like to be able to run the current buffer inside a clojure repl (and all that good stuff)
06:50	asbjxrn	I changed your paste.
06:50	asbjxrn	(And paste.lisp.org is nicer, I think...)
06:50	asbjxrn	(.setRGB #^BufferedImage image (int x) (int y) (int (+ current-time (* x y)))))))
06:50	eevar	okies, thanks
06:51	eevar	yay, way snappier :)
06:52	asbjxrn	I'm not familiar enough with the reflection warnings to understand why there was no reflection warning, though :-/
06:53	sayyestolife	I guess that I need to set the variable 'inferior-lisp-buffer' or something like that?
06:53	eevar	there was (for me) -- i just had no idea where to add the type hint
06:55	asbjxrn	ceninan: it's buffered. Try: (do (print "someting") (flush) (read-line))
06:55	asbjxrn
06:56	sayyestolife	eevar I'm just trying to use the Clojure -> Eval region command (inside clojure-mode)
06:56	ceninan	asbjxrn: thanks :)
06:56	asbjxrn	sayyestolife: Yes, you need to set that. And then M-x run-lisp
06:59	eevar	sayyestolife: here's my ~/.emacs -- http://pastebin.com/m2e181d8d
06:59	eevar	could probably be better, but C-c C-c does eval a sexp once i've started slime
07:01	asbjxrn	slime is more complex, which is good and bad.
07:02	asbjxrn	More features, and more trouble :)
07:16	Raynes	I use a very small subset of Slime's features.
08:32	Chouser	that's actually a pretty good tag line. "Slime: more features, more trouble"
08:36	asbjxrn	I think slime is great for Common Lisp (Well, I used Lispworks myself, but still) But clojure is not quite a perfect match.
08:42	rhickey	Chouser: :)
08:49	AWizzArd	Is there in contrib (or just somewhere) a text/repl based stepper?
08:50	AWizzArd	I got jswat working, but it shows way too much variables, everything the jvm has on its stack. I can't see the Clojure data in the way I am thinking about it, but instead deeply hidden in some collections of collections of collections of ...
08:55	sddiew	what is the best way to assoc in nested vector? (similar to assoc-in for maps)
08:57	AWizzArd	update-in maybe?
08:57	sddiew	wait, it seems that assoc-in works for vectors as well! (but it's not documented)
08:58	rhickey	AWizzArd: IntelliJ has intelligent Java collection displays, which show e.g. maps as key-> val entries, show collection sizes etc, without showing the internals (by default) This all works for Clojure collections as well
08:58	rhickey	,(doc assoc-in)
08:58	clojurebot	"([m [k & ks] v]); Associates a value in a nested associative structure, where ks is a sequence of keys and v is the new value and returns a new nested structure. If any levels do not exist, hash-maps will be created."
08:59	rhickey	,(associative? [1 2 3])
08:59	clojurebot	true
08:59	sddiew	ok :)
09:00	rhickey	sddiew: some of these things are doc'ed in terms of abstractions (as opposed to enumerating all supported types) specifically so they are still true when extended
09:01	sddiew	perfect, because of that "...hash-maps will be created." I thought it's maps-only
09:02	rhickey	sddiew: right, maps are hardwired as the default constructing type, there has to be one
09:02	sddiew	is there any other (even more concise) way to get value from nested vector? better than eg: (reduce get [[[[:x]]]] [0 0 0 0])
09:03	Chouser	hm, it could use (empty coll) instead.
09:03	sddiew	something like a reverse -> macro that would expand to (((some-vector id) id) id)
09:04	sddiew	I know that I can use (-> some-vector (get id) (get id) ...) but...
09:07	sayyestolife	I'm using ClojureBox, and when I evaluate an expression (with C-x C-e) several times I get the error java.lang.reflect.InvocationTargetException
09:07	rhickey	Chouser: empty the root coll? the problem is the assoc of a new vector will only work for index == count
09:07	rhickey	,(doc get-in)
09:07	clojurebot	"([m ks]); returns the value in a nested associative structure, where ks is a sequence of keys"
09:08	sddiew	oh ;) perfect!
09:08	rhickey	,(get-in [[[42]]] [0 0 0])
09:08	clojurebot	42
09:08	sddiew	that's just great
09:10	rhickey	Chouser: begs the question as to whether index of -1 should mean "at end"
09:10	clojurebot	Who??
09:12	Chouser	rhickey: hm... well, that question has certainly come up before.
09:17	rhickey	it doesn't quite work for this, as ([0 1 2 3] -1) == ([0 1 2 3] 3), but what you want for blinds assoc-at-end is (assoc [0 1 2 3] -1 x) == (assoc [0 1 2 3] 4 x)
09:17	Chouser	I always found that natural and convenient in python and ruby
09:17	Chouser	oh. hm.
09:18	rhickey	maybe we need conj-in?
09:18	Chouser	not interested in -0 ?
09:18	Chouser	:-)
09:18	Chouser	oh, really? for this or something else?
09:18	sddiew	what would be equivalent to delete-in/remove-in for nested associative structures?
09:18	clojurebot	for is not a loop
09:19	rhickey	just tried typing it in, not a concept I desire (-0)
09:19	Chouser	oh
09:19	rhickey	,(doc dissoc-in)
09:19	clojurebot	"clojure.contrib.core/dissoc-in;[[m [k & ks as keys]]]; Dissociates an entry from a nested associative structure returning a new nested structure. keys is a sequence of keys. Any empty maps that result will not be present in the new structure."
09:19	sddiew	wow! amazing :)
09:19	Chouser	yeah, I wouldn't have expected you to like the concept of -0
09:20	sddiew	that's why i couldn't find it (contrib), any chance that it would land in core soon?
09:21	rhickey	sddiew: which?
09:21	sddiew	dissoc-in
09:21	rhickey	that's in core
09:21	sddiew	i mean clojure.core (I know that it's in c.c.core)
09:22	sayyestolife	how can I recompile a file inside SLIME? (atm when I try to compile via C-c C-k it complains about stuff being declared/defined more than once)
09:22	rhickey	that should be moved
09:22	rhickey	patch welcome
09:23	rhickey	issue/patch
09:24	sddiew	hmm so I guess conj-in or similar is welcome as well
09:24	rhickey	conj-in has slightly murky semantics - is it assoc-in except for the last step?
09:25	sddiew	sould insert at the n+1 position (for vectors at least)
09:25	rhickey	conj will mean what it does (per collection type) the issue is the inner steps
09:26	Chouser	would it conj anytime an inner step exceeds the length of the vector at that step?
09:26	rhickey	would prefer not to think about vectors specifically
09:26	Chouser	so an error in those cases
09:26	sddiew	by the way, how to insert element in the middle of a vector? assoc and some subvec (n to the end) merged?
09:28	rhickey	Chouser: I'm trying to think about what conj-in means
09:28	rhickey	I think it's maybe not a valid concept
09:28	sddiew	maybe just get-in and conj on the last element? (if it's a collection)
09:28	rhickey	,(doc update-in)
09:28	clojurebot	"([m [k & ks] f & args]); 'Updates' a value in a nested associative structure, where ks is a sequence of keys and f is a function that will take the old value and any supplied args and return the new value, and returns a new nested structure. If any levels do not exist, hash-maps will be created."
09:29	rhickey	might be enough
09:29	Chouser	if it just conj's as the last step, then (conj-in v [0 0 0] :b) is just (update-in v [0 0] conj :b)
09:29	rhickey	heh
09:31	sddiew	so, speaking REST verbs: GET would be get-in, DELETE is dissoc-in PUT is assoc-in POST is update-in f?
09:31	asbjxrn	sddiew: (let [foo (range 20)] (concat (take 10 foo) ['insertedelement] (nthnext foo 10))) kind of works.
09:32	asbjxrn	Uh, not a vector...
09:32	rhickey	sddiew: that's one way to think about it, I guess, but post really changes something and update-in doesn't
09:32	Chouser	so does that invalidate using (empty root-coll) for assoc-in and update-in?
09:32	sddiew	asbjxrn: yeah (vec ...) would do
09:33	Chouser	or just that it remains less useful on vectors because you have to know the length at steps where you'd want to conj
09:33	rhickey	Chouser: there really isn't any more reason to match the root coll than there is to hardwire a map, and maps are easier to create from scratch using assoc
09:34	Chouser	ok
09:34	rhickey	e.g. if the root is a vector of maps
09:34	Chouser	I don't know that I've ever used the new-collection feature of either fn
09:35	rhickey	I think the most common case is maps of maps of ...
09:36	Chouser	so I've been building up a set of functions for interacting with git and assembla and have most of what I need to automate various patch-wrangling tasks (still missing "attach to ticket")
09:36	Chouser	but then this task of creating a new ticket when committing, all in one step, came up.
09:37	sayyestolife	Can any nice person here please try to tell me what is wrong the following code (it's pretty short): http://pastebin.com/d5aad3b91 ?
09:38	asbjxrn	Works fine for me.
09:38	sddiew	is there any simple way to extend clojure writer to put ',' between elements in a vector? what i'm trying to do is to emit valid JSON array from nested vector with strings, reading that in would be straightforward (commas omitted, null would be symbol bound to nil), is that a good idea?
09:38	Chouser	and I was disappointed to find that I was nowhere close to being able to do it with these functions. This case is just different enough that it misses all the apis I've created, and runs into java api areas where I'm weak. A couple hours of hacking at it and I only had the first of 5 or so steps working.
09:39	sayyestolife	asbjxrn okay, damn it :/, my biggest problem with clojure isn't the coding but to get an actual (usable) environment up and running :(
09:39	danlarkin	sddiew: there is a json library you can use in contrib
09:40	Chouser	so last night I spent a couple hours working on the same task as a bash script, and it's already nearly done. Plus it runs faster (because no jvm startup hit). This all makes me a bit sad.
09:40	sddiew	yes I know, but all i need is nested vector with strings, I guess 'read' would be much simpler here (and faster)
09:40	sddiew	read-string actually (and catching eventual exceptions)
09:41	danlarkin	Chouser: yeah clojure doesn't fit every domain
09:41	danlarkin	nor will it ever, I guess
09:41	asbjxrn	Chouser: I'm a Unix admin. I know how you feel. Really want to use clojure for stuff, but ....
09:44	asbjxrn	The one "scripting" niche I found for it was visualization of various stuff by using jfreechart.
09:46	sddiew	somebody (hmm, me?) should put online applet or java web startable waterfront or similar +clojure/clojure-contrib, would make clojure much more accessible for newbies
09:46	Chouser	I know it's popular to say "use the right tool for the job" and apply that to languages and domains, but I tend to believe that's more an idictment of existing languages than any kind of fundamental property of reality.
09:49	Chouser	a general-purpose language should not be like a hammer or screwdriver, it should be like a stack of iron ingots and a forge.
09:49	mattrepl	with languages, sometimes being the right tool means having the right library
09:49	danlarkin	Chouser: to some extent, I suppose. But even if the JVM start time was a non factor, and even if clojure had easy access to idiomatic shell scripting libraries, writing a shell script would still be a better choice a lot of the time. Sure you can make a "dsl" for what you want to do, but sh is already the dsl
09:50	Chouser	danlarkin: but the sh dsl carries a whole lot of baggage with it. some good, and of course that's why it fit well in this case. but some very bad.
09:51	asbjxrn	But isn't that the whole point of the "right tool for the job" saying?
09:52	Chouser	why should I put up with bad baggage?
09:52	asbjxrn	Because you don't care.
09:52	Chouser	but I do!
09:53	Chouser	this bash code I wrote has the most horrible string manipulation code blocks
09:53	asbjxrn	You shouldn't :)
09:53	danlarkin	Chouser: love it for what it is :)
09:53	mccraig	Chouser: 'cos all baggage is bad baggage
09:54	Chouser	I reject all your assertions!! :-) I want all the good features of all the languages in a single language, and nobody's yet proved to me that it's impossible.
09:54	asbjxrn	scripts very quickly become the wrong tool for the job. But for small jobs..
09:55	Chouser	asbjxrn: that's actually a key point. "small jobs" very frequently don't stay that way, and yet you find yourself saddled with whatever language choice was made initially.
09:55	pjstadig	the more general a language is the less useful
09:55	asbjxrn	Ah, but that just means the job changed...
09:56	mccraig	Chouser: i'm not saying it's impossible, just that languages are like species : constantly evolving and yet never perfectly adapted to an ever changing environment
09:56	pjstadig	if a language does everything, then it really does nothing, and you have to do a lot of work to turn those ingots into something useful
09:56	Chouser	hmph.
09:56	asbjxrn	ps -ef \| awk '/styp\id proc/ {print "kill " $2}' \| sh
09:56	asbjxrn	is a "program"
09:57	danlarkin	in the oh-so-powerful sh dsl :)
09:58	asbjxrn	And when running this I don't care if awk doesn't do closures or referential transparency.
09:58	newbie	hey all, when i execute this for loop in repl i get nil printed as well besides the number (for [y (range 0 100)] (println y ) ) am i doing it wrong or is this the behaviour?
09:59	Chouser	~for
09:59	clojurebot	for is not used enough
09:59	Chouser	wrong!
09:59	Chouser	~for
09:59	clojurebot	for is not a loop
09:59	Chouser	there you go
09:59	Chouser	newbie: 'for' is not meant for side-effects. It's lazy.
10:00	pjstadig	,(for [y (range 1 100)] (println y))
10:00	clojurebot	(nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil)
10:00	asbjxrn	,(doc for)
10:00	clojurebot	"([seq-exprs body-expr]); List comprehension. Takes a vector of one or more binding-form/collection-expr pairs, each followed by zero or more modifiers, and yields a lazy sequence of evaluations of expr. Collections are iterated in a nested fashion, rightmost fastest, and nested coll-exprs can refer to bindings created in prior binding-forms. Supported modifiers are: :let [binding-form expr ...], :while test, :when test.
10:00	Chouser	newbie: so what's going on there is your 'for' is producing a lazy seq of whatever println returns (nil for each number)
10:01	Chouser	...but when the repl prints that seq of nils, it has to realize each value which cause the side-effect of println (actually printing the number) to happen at each step
10:02	Chouser	newbie: so you have to decide if you actually want the side-effect (in which case use 'doseq') or if you want to produce a lazy-seq (use 'for' but get rid of the println)
10:02	mattrepl	newbie: (doseq [x (for [y (range 1 100)] y)] (println x))
10:02	Chouser	huh
10:04	newbie	what i am trying to do is iterate over x and y values ( coordinates ) i tried doseq but when i have for inside a for it only prints nil?
10:05	Chouser	,(for [x (range 3), y (range 3)] [x y])
10:05	clojurebot	([0 0] [0 1] [0 2] [1 0] [1 1] [1 2] [2 0] [2 1] [2 2])
10:07	sddiew_	so, string is not associative, is it a bug in get-in?
10:08	Chouser	,(get-in ["abcde"] [0 3]) ; like this?
10:08	clojurebot	\d
10:09	sddiew_	,(associative? "abcde")
10:09	clojurebot	false
10:09	newbie	one last question how can i call a function using these x y values?
10:09	sddiew_	sure it is ok for ordinary get
10:10	Chouser	,(for [x (range 3), y (range 3)] (+ x y))
10:10	clojurebot	(0 1 2 1 2 3 2 3 4)
10:11	newbie	this maybe a stupid question but how can i call + on x y but not println?
10:12	Chouser	do you mean "why?" because + has no side-effects, but println does.
10:13	asbjxrn	newbie: You can still call println, but println will only return nil, the printing is a side-effect. So collecting the result of a println only gives you nil.
10:15	asbjxrn	you could use println-str instead:
10:15	asbjxrn	,(for [x (range 3) y (range 3)] (println-str x y))
10:15	clojurebot	("0 0\n" "0 1\n" "0 2\n" "1 0\n" "1 1\n" "1 2\n" "2 0\n" "2 1\n" "2 2\n")
10:15	Chousuke	newbie: for is not a looping construct, it's a list comprehension :)
10:15	newbie	ok now i get the nil is the return value of print and numbers are written inside print thats the reason i am seeing nil, am i right?
10:16	asbjxrn	right
10:17	newbie	coming from java i picked for because thats what i am used to but if you were to iterate a bunch of x y coordinated and do some calculation on them which looping construct would you use? is using for in this case a wrong thing to do?
10:18	mblinn	depends on what you're trying to do
10:18	mblinn	there are a lot of higher level functions that help with that sort of thing
10:18	mblinn	map, reduce, etc
10:18	mblinn	so uh, what are you trying to do :-)
10:19	newbie	i will iterate each pixel on a panel and depending on the coordinates paint a dot on its location
10:20	Chousuke	then you need to use doseq or loop
10:22	newbie	thank you all.
10:24	asbjxrn	What is the reasoning for the [{a :a b :b :or {a 1 b 2}}] destructuring? Why isn't the "or hash" {:a 1 :b 2}?
10:25	Chousuke	asbjxrn: the a, b, are the names you bind to, and the :a, :b are the keys you use to look up the names.
10:26	Chousuke	in the :or hash, there's no need for the lookup keys, only the names to bind to.
10:26	asbjxrn	Right. But then I would have thought it would have been {a :a b :b :or [a 1 b 2]}
10:27	Chousuke	I guess it could be {:a 1 :b 2} too, as in, the default map to destructure.
10:29	asbjxrn	Right, that's the way I was thinking. Doesn't really matter since it's a special case anyway, but I found it a bit funny.
10:29	thickey_	isn't it {} instead of [] for lookup reasons when it uses the :or? i.e. it's looking up the value associated with a
10:29	Chousuke	but you could have something like [{a "foo" b 0 :or {a 2 b 3}}] which is a bit clearer that :or {"foo" 2 0 3}
10:31	asbjxrn	Right, that's a good point.
10:34	asbjxrn	thickey_: Ah, maybe the local vars is built up by starting with the "or hash" and assoc'ing the rest of the keys/values? (No, I haven't read the source, and I suspect that local vars may not be stored in a hash like that...)
10:35	asbjxrn	(BTW: What's the right name in this case? "vars" is obviously wrong as it has a special meaning.)
10:35	Chouser	locals
10:36	Chouser	:-)
10:36	Chouser	,(macroexpand '(let [{a :a b :b :or {a 1 b 2}} nil]))
10:36	clojurebot	(let* [map__2197 nil a (clojure.core/get map__2197 :a 1) b (clojure.core/get map__2197 :b 2)])
10:37	sddiew_	,(get-in [:a [:b]] [1 0]) ; works
10:37	clojurebot	:b
10:37	sddiew_	,(dissoc-in [:a [:b]] [1 0]) ; fails, bug?
10:37	clojurebot	java.lang.Exception: Unable to resolve symbol: dissoc-in in this context
10:38	sddiew_	provided that dissoc-in was use-d
10:38	Chousuke	I don't think that's a bug
10:38	Chousuke	vectors don't support dissoc
10:38	asbjxrn	,(macroexpand '(let [{a :a b :b :or {a 1}} {:b 2}]))
10:38	clojurebot	(let* [map__2207 {:b 2} a (clojure.core/get map__2207 :a 1) b (clojure.core/get map__2207 :b)])
10:39	sddiew_	I guess I should use update-in instead but... one level up?
10:41	sddiew_	it's a bit inconsistent with the rest of -in functions that work on associative structures
10:45	sddiew_	is there a better way to 'remove' item from a vector than concat+take/drop or concat+subvec?
10:45	Chouser	maybe (into (subvec ...) (subvec ...))
10:46	sddiew_	which would be fastest? :)
10:46	Chouser	I think the meaning of that is pretty clear, and using into,subvec like that is O(n) where n is the length of the second subvec
10:47	sddiew_	subvec is much faster than take/drop (that work on sequences so O(n)) but how about into vs concat etc.?
10:47	Chouser	if you want a vector in the end, you're not going to do better than O(n) as with the into
10:48	sddiew_	hmm, yes, I want vector, too bad that there is no dissoc for vectors :(
10:48	Chouser	the underlying data structure simply doesn't support that
10:49	sddiew_	hmm is it some kind of trie?
10:49	Chouser	indeed
10:50	sddiew_	ok I guess I have to live with that (much better and more performant for most other problems though)
10:58	rhickey	persistent finger trees would be a welcome contribution
10:59	Chousuke	hm, I vaguely remember seeing someone working on an improved persistent map data structure on github
10:59	Chousuke	I wonder what that was.
11:29	sayyestolife	hm
11:29	sayyestolife	I can do a (require 'myfile) but a (require :reload 'myfile) fails due to (reflect.InvocationTargetException), any ideas?
11:34	drewr	I think I like defnm better than defn-memo
11:38	drewr	good work, btw :-)
11:42	Chouser	defn-memo too wordy?
11:46	drewr	for me, but I like brevity to the extreme
11:50	Chousuke	I'd go with defn-memoize :P
11:50	Chousuke	though memo is fine too
11:51	Chousuke	unnecessary abbreviation is the root of all evil.
11:51	drewr	it's actually unnecessary unabbreviation :-)
11:51	Chousuke	not to mention that defnm is unpronounceable.
11:52	sddiew_	clojure is not arc ;)
11:52	drewr	sddiew_: I like that aspect of arc...
11:52	Chousuke	seriously, though, I wish people didn't always abbreviate things so much
11:52	Chousuke	it just makes stuff unreadable.
11:52	drewr	it's the other way around for me
11:52	clojurebot	for is not a loop
11:53	Chousuke	defnm is so close to defn that it looks like a typo.
11:53	Chouser	I didn't use defn-memoize because memoize is a verb and ends up in the wrong place there
11:53	Chouser	maybe def-memoize-fn :-P
11:53	drewr	Chousuke: defn- is too
11:54	sayyestolife	excuse the language but, holy shit it feels good when you make stuff work by yourself :)
11:54	Chousuke	drewr: yeah, but in that case there's a convention
11:54	Chousuke	drewr: - = private
11:54	sddiew_	hm, maybe the way to go is to create abbreviations, similar to call-with-current-continuation => call/cc
11:54	Chouser	I didn't use defmemo because I didn't want to lose the fn in there
11:54	drewr	Chousuke: I'm trying to shape future conventions :-)
11:54	clojurebot	drewr: the fn created by future (like all fns) doesn't close over dynamicly scoped stuff
11:54	Chouser	hah!
11:54	drewr	clojurebot: shut your hole
11:54	clojurebot	excusez-moi
11:54	Chousuke	clojurebot is chatty today :p
11:55	Chouser	I stuck the dash in there becase the nm together in defnmemo makes my eyes go buggy
11:55	Chouser	all of which matters to me a bit less than the little race condition in my definition
11:56	drewr	you guys put way too much stock into what looks immediately "right"
11:56	drewr	what matters is what you type over and over again
11:57	drewr	(not that defn-memo) will be as popular as defn
11:57	sayyestolife	well, I've heard that you often write code once but look at it a thousand times
11:57	Chouser	but I think that's ok too because even if you're calling defn-memo to redef an existing var, if something calls it in the race state you just get the un-memoized new version, which shouldn't hurt anybody too much
11:57	drewr	that close paren should have been at the end
11:58	drewr	sayyestolife: I've never understood that argument; once you know what stuff means, it makes sense
11:58	Chousuke	drewr: I still don't like looking at alphabet soup
11:58	drewr	unmaintainability comes in when you make fns too big and don't modularize properly
11:59	Chousuke	drewr: having proper names for things helps with being able to discern them quicker amid other code.
11:59	Chouser	I'm glad it's defn not define-function
11:59	drewr	yes
11:59	Chouser	seeing that written out wouldn't help me one whit
12:00	drewr	"defnm" has a distinct flavor to it; I would get used to it
12:00	Chousuke	well, it's something you write very often.
12:00	Chouser	Chousuke: exactly
12:00	Chouser	and read often
12:00	Chouser	and it has a whole lot of character of its own
12:00	drewr	I will concede since I don't then to memoize very often
12:00	Chousuke	defn- is fine because it's basically defn
12:01	Chouser	memoizing a fn is not terribly common, and the word "memo" conveys a whole lot of meaning that "m" doesn't
12:01	drewr	I always do a double-take at defn-
12:01	Chousuke	defnm is also basically defn, but the m is not a convention for "memoize" so it fails
12:02	drewr	wow, s/then/tend/ up there
12:02	Chousuke	and the thing that it's easy to typo defn into defnm
12:02	Chousuke	and then you won't be able to tell whether that's intended or not.
12:02	Chouser	it's a bit unfortunate that (defn- foo ...) and (defn -foo ...) are both valid and mean very different things. ...not that I have any better alternatives to suggest. :-P
12:04	Chousuke	I'm just saying that if you do abbreviations that are not conventions, they must be obvious :)
12:04	Chousuke	m is not.
12:04	drewr	I screw code up no matter what; I prefer brevity so I can screw it up more quickly and be done
12:04	Chousuke	typing a couple fewer characters won't make you code faster.
12:04	drewr	Chousuke: fair point
12:05	Chousuke	no-one codes as fast as they type, anyway
12:05	drewr	the above point
12:05	Chousuke	if they do, something's wrong :)
12:05	drewr	I dunno, with clojure I can bust out a thought pretty quickly
12:05	sddiew_	how about defnemo ;)
12:06	drewr	defnoize
12:06	drewr	has a nice ring to it
12:06	drewr	defn01ze
12:06	sddiew_	:)
12:06	Chousuke	or for the british, defnoise
12:18	guille_	hi
12:18	guille_	what do you use for taking a look to javadocs from clojure-mode?
12:53	sayyestolife	I know that Clojure uses STM (I'm not very familiar with that), but I'm making a server and obviously I'd like to server a lot of people at the same time; should I still use java threads?
12:53	Chousuke	Threads and STM are not mutually exclusive :)
12:54	Chousuke	in fact, without threads the STM would be rather useless.
12:54	rhickey	has anyone tried the ensure branch?
12:54	cemerick	sayyestolife: STM allows you to write programs that have reliable semantics in a multithreaded environment.
12:54	sayyestolife	heh, so threads is the way to go in this case?
12:54	Chousuke	but instead of using threads explicitly you might be able to use agents, too
12:54	sayyestolife	agents you say, I better look that up, thanks :)
13:01	sayyestolife	I might be stupid but I didn't really get http://clojure.org/agents, do any of you have some other resources regarding agents?
13:02	cemerick	rhickey: Since you're not on twitter, FYI: https://twitter.com/headius/status/2552807823
13:03	rhickey	cemerick: I'm on twitter, I just don't follow anyone or say much :)
13:03	rhickey	very interesting though, thanks
13:05	rhickey	must be nice to work at Sun and get the things you need :)
13:09	rhickey	moving it into Java 6 greatly enhances the viability
13:29	drewr	sayyestolife: think of agents as refs that don't get updated immediately
13:30	drewr	and aren't transactional
13:30	sayyestolife	mkay, (another, unrelated question) is there an easy way to have a variable parameter list such as in python where you can retrieve all of the argumentsin a list?
13:31	drewr	yes, that's what [... & args] does when you see it
13:31	drewr	args is a seq of the remaining parameters
13:32	sayyestolife	oh I see
13:32	sayyestolife	thanks
13:33	drewr	,((fn [a b & c] c) :foo :bar :baz :quux)
13:33	clojurebot	(:baz :quux)
13:43	sayyestolife	I might be totally out there but; when I have a list of items I'd like to print, wouldn't a map do the job?
13:43	sayyestolife	I tried with (map #(print (str %)) args) but it didn't print anything at all
13:44	cemerick	rhickey: the notion of it requiring a flag and an rt.jar addition is less than ideal.
13:47	ceninan	sayyestolife: why not use doseq?
13:47	ceninan	,(doseq [x [1 2]] (println x))
13:47	clojurebot	1 2
13:48	sayyestolife	ah thanks
13:52	cemerick	sayyestolife: map is lazy, which is why nothing was printed. see doall
13:52	cemerick	,(doall (map println (range 5)))
13:52	clojurebot	(nil nil nil nil nil)
13:52	clojurebot	0 1 2 3 4
13:52	cemerick	but yes, doseq is more idiomatic
13:55	maacl	I have a recursive call like this inside a traceback-lcs function (traceback-lcs m s1 s2 (- i 1) (- j 1)) (nth s1 (- i 1)). The call generates the return value of the function. If s1 is a string i can just coerce the whole thing into a string and get a sensible return value that way, but the rest of the traceback-lcs function works on all ordered collections. How do I coerce this into returning a collection of the same class as s1?
14:03	Chousuke	maacl: hm, please clarify. instead of one call, you wrote two separate expressions :)
14:03	Chousuke	but maybe something like this
14:05	Chousuke	,(let [f (fn [coll] (into (empty coll) [1 2 3 4]))] [(f {}) (f [])]
14:05	clojurebot	EOF while reading
14:05	Chousuke	oops
14:05	Chousuke	,(let [f (fn [coll] (into (empty coll) [1 2 3 4]))] [(f {}) (f [])])
14:05	clojurebot	java.lang.IllegalArgumentException: Don't know how to create ISeq from: Integer
14:05	Chousuke	hm
14:05	maacl	sorry missed a paren at the end. when coercing to a string it looks like this: (str (traceback-lcs m s1 s2 (- i 1) (- j 1)) (nth s1 (- i 1)))
14:07	Chousuke	hm
14:10	Chousuke	now I'm more confused as to why my example gives that error.
14:11	Chousuke	:o
14:11	Chousuke	,(empty {})
14:11	clojurebot	{}
14:11	Chousuke	,(into (empty {}) [1 2 3 4])
14:12	clojurebot	java.lang.IllegalArgumentException: Don't know how to create ISeq from: Integer
14:12	Chousuke	no wonder. :P
14:12	Chousuke	,(let [f (fn [coll] (into (empty coll) [[1 2] [3 4]]))] [(f {}) (f [])])
14:12	clojurebot	[{3 4, 1 2} [[1 2] [3 4]]]
14:13	Chousuke	anyway, into might do what you want.
14:14	Chousuke	though sadly, it doesn't work for strings
14:15	Chousuke	(doc show)
14:15	clojurebot	"clojure.contrib.repl-utils/show;[[x] [x selector]]; With one arg prints all static and instance members of x or (class x). Each member is listed with a number which can be given as 'selector' to return the member object -- the REPL will print more details for that member. The selector also may be a string or regex, in which case only members whose names match 'selector' as a case-insensitive regex will be printed. Finall
14:15	maacl	thanks - will give it some more thought
14:16	sddiew_	any reason why you use (into (empty {}) ...) and not simply (into {} ...) ?
14:16	Chousuke	sddiew_: well, the actual parameter might not be empty
14:16	Chousuke	,(let [f (fn [coll] (into (empty coll) [[1 2] [3 4]]))] (f {1 2}))
14:16	clojurebot	{3 4, 1 2}
14:16	Chousuke	bad example, though :P
14:17	Chousuke	,(let [f (fn [coll] (into coll [[1 2] [3 4]]))] (f {5 6})); if you remove the empty
14:17	clojurebot	{3 4, 1 2, 5 6}
14:17	sddiew_	actually what's the use of empty? and what is the difference between (empty {}) and eg. (identity {})?
14:17	Chousuke	nothing
14:18	Chousuke	,(empty {1 2}); this case differs however
14:18	clojurebot	{}
14:18	sddiew_	ah ok, in case you want to make empty collection of some type of non-empty one
14:18	Chousuke	useful for polymorphism
14:18	sddiew_	sure sure, I guess I need some sleep ;)
14:46	sayyestolife	I have a function where I call print; this function gets called several times inside a loop, but it isn't until the last call in the loop that everything gets printed. How come?
14:47	kotarak	sayyestolife: try to call (flush) in the loop.
14:47	sayyestolife	mkay
14:48	sayyestolife	that fixed it, thanks.
15:11	guille_	does exist a function to convert a symbol to a string?
15:11	kotarak	(doc name)
15:11	clojurebot	"([x]); Returns the name String of a symbol or keyword."
15:11	kotarak	(doc namespace)
15:11	clojurebot	"([x]); Returns the namespace String of a symbol or keyword, or nil if not present."
15:12	guille_	thanks
16:24	j-dot	anyone know what would have changed between 1.0 and now regarding the way Clojure is loaded?
16:24	j-dot	I'm trying to write an Ant task in Clojure using gen-class and a simple build file works fine with 1.0, but not with HEAD
16:25	lisppaste8	j-dot pasted "Ant task written in Clojure" at http://paste.lisp.org/display/83318
16:25	j-dot	that paste is a stripped down task the exhibits the behavior
16:26	kotarak	Which is?
16:26	j-dot	with 1.0, "Ah-ha" is echoed as expected
16:27	j-dot	with HEAD, I get the exception I'm annotating on that paste now
16:27	lisppaste8	j-dot annotated #83318 "Exception with HEAD" at http://paste.lisp.org/display/83318#1
16:28	j-dot	mainly, this: "java.lang.IllegalStateException: Var clojure.core/refer is unbound."
16:28	j-dot	that gets thrown when clojure.zip goes to refer to clojure
16:30	lisppaste8	j-dot annotated #83318 "Example build file for testing the task" at http://paste.lisp.org/display/83318#2
16:31	kotarak	oerk... ugly... but sorry: no clue here.
16:31	j-dot	eh, no worries ... thanks anyway. Maybe I'll send it off to the list
16:33	Chouser	know how to use git bisect? :-)
16:34	j-dot	nope, but I don't expect I'll find a much better time to learn
16:38	Chousuke	it's pretty easy.
16:38	j-dot	ahh, git bisect looks very cool. Thanks, Chouser!
17:07	texodus	Is there any way to add java annotations to clojure proxy functions?
17:11	hiredman	nope
17:17	texodus	tragic
17:19	lisppaste8	guille_ pasted "Trying to emulate normal recursion (without success)" at http://paste.lisp.org/display/83321
17:19	guille_	would you take a look to the paste above about how would i change it to use recur? (from PAIP)
17:20	guille_	i've changed the function name by recur, but it seems that you can only call recur from the bottom
17:21	Chousuke	recur only works for tail recursion
17:21	opqdonut	yeh
17:21	Chousuke	if you don't have tail recursion, you can't get the optimisation anyway and need to use regular recursion :)
17:24	guille_	i see. thanks
17:24	Chousuke	but it does look like you could do that without recursion.
17:24	Chousuke	hmm
17:27	Chousuke	but before I go and do that, you should rename variable-p to "variable?".
17:28	guille_	is it not recommended to use -p for booleans?
17:29	hiredman	use ?
17:32	Chousuke	guille_: Clojure follows the Scheme convention that predicates end with ?
17:35	Chousuke	hmm, it looks like your pattern matching algorithm might need to be "truly" recursive after all.
17:36	kotarak	does a zipper help in this case?
17:40	guille_	it's supposed to match more than one word (up to the next word from the placeholder), so actually the "zipper" is the function itself
18:00	Chousuke	guille_: you want something like this? http://gist.github.com/144035
18:01	Chousuke	it's not iterative, but I don't think you can avoid keeping a stack in any case.
18:08	guille_	Chousuke: yes, concise code yours :)
18:08	Chousuke	github screwed up the indentation though
18:08	Chousuke	but the source is my emacs. it's using tabs again
18:08	Chousuke	for whatever reason.
18:09	Chousuke	I'm sure I disabled tabs.
18:12	Chousuke	I even have "(setq indent-tabs-mode nil); Aquamacs is idiotic" at the top of my init.el but it seems to have no effect :-(
18:23	guille_	i switched two days ago from aquamacs to cocoa emacs (in macports "emacs-app-devel") because some problems in latex-mode and I don't regret it. Also sometimes aquamacs decided to close erc buffers when killing the contiguous...
18:27	Chousuke	I might do that too. Though does it have similar support for trickery with the alt key as aquamacs does?
18:28	Chousuke	I need alt-2 to output @ because I have a finnish keyboard layout and no altgr (this being a mac) :/
18:29	guille_	i use in .emacs: (setq mac-command-modifier 'meta) (setq mac-option-modifier nil) so you have meta in command and alt free
18:31	Chousuke	hmm.
19:23	grrrt	I would like to define an event "stream" as a lazy seq. The elements of the seq would be "change" events from, say, a ref (using add-watch to see changes) or a Swing widget (using a ChangeListener or ActionListener for instance). The seq would be blocking, i.e. if you iterate over it, it would wait until new events are available.
19:24	grrrt	is that a dumb idea?
19:27	ceninan	funny, I had a similiar idea earlier today when playing around with DSLs
19:27	clojurebot	The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' (I found it!) but 'That's funny ...' -- Asimov
19:28	Chousuke	Doesn't java provide a BlockingQueue or something?
19:28	ceninan	far too inexperienced to know if it's a good idea though :/
19:28	grrrt	Chousuke: it does. But I'd like to avoid writing java :)
19:28	grrrt	unless it's the best way to do it ofcourse
19:29	Chousuke	grrrt: you'd be writing Clojure :p
19:29	Chousuke	just using a java library.
19:29	Chousuke	seqs are persistent, too. do you want to hold onto the events?
19:29	grrrt	hm
19:29	grrrt	perhaps not...
19:29	Chousuke	though only persistent as long as you hold onto the head.
19:29	grrrt	ah that's good
19:29	grrrt	I'm not sure yet, still experimenting...
19:30	grrrt	I'm inspired by a paper about FrTime, about a FRP gui library in scheme
19:30	Chousuke	should others be able to "consume" the events?
19:31	Chousuke	or just see a list of them
19:31	Chousuke	in the latter case, a seq of events them could be useful.
19:31	grrrt	I was thinking, you could have a function that iterates over a seq, consuming events as they appear
19:32	Chousuke	if you consume them, then it's better to have a BlockingQueue I think
19:32	grrrt	Still not sure if that's the way to go, but I'm trying to find alternatives to the classic event callback mechanism
19:32	grrrt	yeah that sounds sensible
19:32	Chousuke	you can also try using agents.
19:32	ceninan	just a quick newb-question here; could you do what grrrt wants, but somehow "kill" a queue?
19:33	Chousuke	agents queue the actions sent to them automatically.
19:33	grrrt	I'm actually using that already
19:33	grrrt	I have an 'in-ui' macro that calls Swing's invokeLater
19:33	ceninan	(ie. no more events are accepted)
19:34	grrrt	an agent + queue combination sends the result of whatever's called in the ui-thread to the caller of in-ui
19:35	grrrt	hm. food for thought, thanks Chousuke
20:36	grrrt	I often find myself wanting a 'let-default' function, e.g. in situations like this: (let [v (if nil? val) "some default" val])
20:36	grrrt	is there a better way to do this?
20:37	arbscht_	try (let [v (or val "default")] ..)
20:38	grrrt	that'd work in this case, but I wonder if there's a more general way of doing it (i.e. with predicates other than nil?)
20:39	grrrt	(let [s (if sequential? arg) arg [arg]) is another one
20:39	grrrt	- except I'm missing a few () there
20:41	arbscht_	I can't think of a better way to express that
20:41	arbscht_	it seems clear enough as it is
20:41	grrrt	glad I'm not the only one :)
20:42	grrrt	ok fair enough
21:07	rhickey	(or val default) is the right idiom for nil/non
21:08	grrrt	rhickey: thanks.
21:15	JAS415	is there a way to tell (in java) if a class is a subclass of another class
21:16	grrrt	instanceof would do it
21:16	grrrt	("hello world" instanceof String) == true
21:17	JAS415	what if I have something like 'clojure.lang.LazilyPersistentVector' and 'clojure.lang.IPersistentVector'?
21:18	grrrt	,(doc isa?)
21:18	clojurebot	"([child parent] [h child parent]); Returns true if (= child parent), or child is directly or indirectly derived from parent, either via a Java type inheritance relationship or a relationship established via derive. h must be a hierarchy obtained from make-hierarchy, if not supplied defaults to the global hierarchy"
21:18	JAS415	and i want to dispatch depending on whether a metadata tag is a subclass of 'clojure.lang.IPersistentVector'
21:18	JAS415	oo cool
21:18	JAS415	that would do it
21:24	ataggart	so, I need to modify the last segment in a variable-length list of values. e.g., '("a" "b" ) --> '("foo" "baz"). Is there a better way than something like (cons new-val (drop 1 (reverse orig-list)))
21:24	ataggart	oops
21:24	ataggart	that example should be ("a" "b" "c") --> ("a" "b" "d")
21:26	grrrt	ataggart: instead of using drop/reverse you could use the butlast function
21:27	ataggart	yeah I looked at that but couldn't figure out how to append the new value to the end of it
21:28	ataggart	and my example solution should actually be (reverse (cons new-val (drop 1 (reverse orig-list))))
21:29	ataggart	which just looks bad to me
21:29	grrrt	,(concat (butlast ["a" "b" "c"]) ["d"])
21:29	clojurebot	("a" "b" "d")
21:29	grrrt	that's one option - don't know if that's the best
21:30	ataggart	ah yes that would do it.
21:31	ataggart	it has to bet better than a double reverse
21:31	ataggart	thanks!
22:29	JAS415	is there a way to update metadata?
22:29	JAS415	(and preserve what is already there)
22:33	JAS415	,(def alter-meta!)
22:33	clojurebot	DENIED
22:33	JAS415	,(doc alter-meta!)
22:33	clojurebot	"([iref f & args]); Atomically sets the metadata for a namespace/var/ref/agent/atom to be: (apply f its-current-meta args) f must be free of side-effects"
22:52	JAS415	why would this work at the repl but not in a source file?
22:52	JAS415	(let [inlining-arity (rule-set (fn [x] (> x 1)))
22:52	JAS415	set-symbol-inline-arity (fn [& symbols]
22:52	JAS415	(map (fn [x] (println x) (alter-meta! x #(assoc %1 :inline-arities inlining-arity))) symbols))]
22:52	JAS415	(set-symbol-inline-arity #'+ #'* #'- #'/ #'< #'<= #'> #'>= #'==))
22:52	JAS415	(source file at toplevel)