#clojure – 2008-10-07

2008-10-07

03:07	cccc	can i raise errors/exceptiosn deliberately in clojure?
03:07	cccc	like if i define factorial and someone passes -1 can i have it raised a "factorial not defined for negative numbers"-error then or i should just return nil?
03:26	hoeck	cccc: just like in java, only with parens :) : (throw (Exception. "exception message"))
03:55	Lau_of_DK	Gents - Good morning - Can somehere show me how to apply zip/edit ? I'm not getting the [loc f & args] syntax
04:13	hoeck	Lau_of_DK: good morning, maybe: (apply zip/edit loc f arglist)?
04:22	Lau_of_DK	Its not quite working out for me
04:22	Lau_of_DK	Altering a single node in an xml tree is proving pretty difficult
04:24	hoeck	I'm don't like xml, i try to ignore it where i can
04:25	hoeck	I'm / I
04:25	Lau_of_DK	oh... I think its quite handy
06:00	Lau_of_DK	user=> (apply (fn [x] (str x)) "clj")
06:00	Lau_of_DK	java.lang.IllegalArgumentException: Wrong number of args passed to: fn
06:00	Lau_of_DK	What wrong with this ?
06:09	Vanessa	i want to be able to: cons (val, result-of-function) to ((hello 10) transfer 20))
06:09	Vanessa	how do i cons a list and have it eval a function inside he list?
06:09	Vanessa	like if i quite it just conses the quoted expression instead of the result of it
06:10	Vanessa	like hello anywhere there?
06:14	Lau_of_DK	You mean something like this:
06:14	Lau_of_DK	(def fib-seq
06:14	Lau_of_DK	(concat
06:14	Lau_of_DK	[0 1]
06:14	Lau_of_DK	((fn rfib [a b]
06:14	Lau_of_DK	(lazy-cons (+ a b) (rfib b (+ a b)))) 0 1)))
06:14	Lau_of_DK	?
06:14	H4ns	Lau_of_DK: apply expects an argument list to apply to a function, not a single argument
06:14	H4ns	lisppaste8: url
06:14	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
06:15	H4ns	please use that for pasting code that is longer than one line.
06:15	Lau_of_DK	H4ns, I will submit to your will
06:17	Vanessa	(cons '(1 (* 2 1)) '((3 4) (5 6))) ->
06:17	Vanessa	((1 (* 2 1)) (3 4) (5 6))
06:17	Vanessa	but i want (* 2 1) to be evaluated
06:17	Vanessa	-> ((1 2) (3 4) (5 6))
06:17	H4ns	Vanessa: you are quoting '(1 (* 2 1)), so nothing in it is evaluated
06:18	H4ns	Vanessa: (cons (list 1 (* 2 3)) ()) => ((1 6))
06:22	lisppaste8	vanessa pasted "wordcounting" at http://paste.lisp.org/display/68095
06:22	Vanessa	^^
06:22	Lau_of_DK	Whats a kiteboard?
06:23	Vanessa	wait i changed
06:23	Vanessa	lau: something you danes are quite good
06:23	Vanessa	i changed a little wait
06:24	Vanessa	^^
06:25	Lau_of_DK	You changed?
06:25	lisppaste8	vanessa pasted "wordc" at http://paste.lisp.org/display/68096
06:27	Vanessa	(cons (list 1 2) '()) doesnt work, that seems to be the problem
06:27	Vanessa	why not?
06:27	Vanessa	(cons 1 '()) enither
06:28	Vanessa	works in other lisps
06:28	Lau_of_DK	Would (cons 1 (list nil)) work for you ?
06:28	Vanessa	nil
06:28	Vanessa	yes
06:30	Lau_of_DK	user=> (zip/edit (first (xml-> xml-data :l1 :l2)) (fn [x] (parse-str x)) (list "<test>new val</test>"))
06:31	Lau_of_DK	Can somebody fill me into, as to why this complains of bad number of args for fn
06:40	Lau_of_DK	rhickey, you wrote this stuff initially, how do I change the content of 1 node in an XML tree, and still keep the rest of the tree?
06:40	hoeck	Lau_of_DK: cause zip/edit expects a function that takes 2 args, but your fn takes only one arg
06:41	Lau_of_DK	How would you set it up ?
06:41	leafw	Lau_of_DK: (fn [x y] ( .... ))
06:42	hoeck	Lau_of_DK: mind pasting a small example with xml testdata?
06:42	Lau_of_DK	sure
06:45	lisppaste8	Lau_of_DK pasted "XML Edit" at http://paste.lisp.org/display/68097
06:45	Lau_of_DK	This hopefully gives you an idea of what Im going for
06:50	Vanessa	how can i set clojure-mode to just load the file into the interpreter in the other window, not start the interpreter in the currecnt window?
07:00	Lau_of_DK	hoeck , you got the idea? :)
07:06	hoeck	yeah, just give me a second
07:10	Lau_of_DK	sure :)
07:18	Vanessa	if i ahve a (apply list is-a-hash-map) and want to sort the result(looking like (["hello" 1] ["transfer" 12]) ) on the second key(the ints), how do i do that?
07:25	rhickey	Vanessa: (sort #(compare (val %1) (val %2)) {"hello" 1 "atransfer" 12})
07:26	rhickey	you don;t need the apply list
07:27	Vanessa	ok but ^^ is not working
07:28	rhickey	do you have the latest Clojure?
07:28	rhickey	svn 1053
07:28	Vanessa	: Unable to resolve symbol: compare in this context
07:28	Vanessa	nah from june
07:28	rhickey	ah
07:29	Vanessa	i download the new one
07:29	Vanessa	now
07:40	Vanessa	shouldnt running clojure.jar from the win com prompt start the repl?
07:40	Vanessa	when i do nothign happens
07:40	Vanessa	java clojure...
07:41	Vanessa	exception blarf
07:41	Vanessa	should i be able just unzip and then do java clojure.jar in the directory?
07:41	H4ns	java -cp clojure.jar clojure.lang.Repl
07:42	rhickey	or java -jar clojure.jar
07:42	rhickey	Vanessa: by latest I meant the latest from svn
07:43	rhickey	might work with sept release
08:05	Vanessa	how do i sort in descending order so i dont have to reverse
08:05	Vanessa	ah change 1 and 2
08:05	Vanessa	what si it that it does really?
08:06	Vanessa	(sort #(compare (val %2) (val %1)) tuples))
08:06	Vanessa	% is usually mod but not here right
08:07	drewr	#() is alternate reader syntax for an anonymous fn.
08:07	drewr	% is bound to the arg, if there is only one.
08:07	drewr	%1, %2, etc. are bound to the args for more than one.
08:08	parth_m	Venessa: http://en.wikibooks.org/wiki/Clojure_Programming#Anonymous_Functions
08:08	abrooks	%& is the "rest" argument. I learned about that recently.
08:14	drewr	Cool, didn't know that.
08:17	Chouser	Lau_of_DK: after "changing" a zip node, use zip/root on the result to get the whole tree including any changes.
08:36	Vanessa	how can i sum over this? (("account" 21) ("BUSINESS" 22) ("email" 23) ("money" 27))
08:37	Vanessa	(reduce + #( something?
08:37	Vanessa	iw ant to some the ints obv...
08:37	rhickey	if it was still in a map you could just (reduce + (vals amap))
08:39	lisppaste8	hoeck annotated #68097 with "xml edit" at http://paste.lisp.org/display/68097#1
08:40	hoeck	Lau_of_DK: you're right, using xml this way is really handy
08:42	hoeck	btw, chouser: you rock! for doing this xml stuff and gen-interface! thanks!
08:45	gnuvince	Vanessa: how about (reduce + (map #(nth % 1) coll))?
08:49	Chouser	hoeck: heh, thanks.
08:52	lisppaste8	glarf pasted "spamfilter" at http://paste.lisp.org/display/68099
08:52	glarf	i posted my spamfilter ^^
08:53	glarf	comments on style and stuff is appreciated
08:53	glarf	my first lispprogram that actually doesns omething useful :)
08:54	glarf	it is a spamfilter that takes a file with spamemails, good emails and then an email to test and then accuracy(how many of the most common words found to compare)
09:26	Chouser	glarf: rather than [w (hd words) wr (tl words)], you could say [[w & wr] words] -- shorter, and doesn't need the non-standard hd and tl
09:36	glarf	cool haskell-like patternmathcin, very nice
09:36	glarf	how do i force float-division?
09:37	Chouser	I don't know enough haskell to say, but I think it's a somewhat simpler mechanism -- "destructuring"
09:37	glarf	do i have to convert one of the dividors to float or do * 1.0 ?
09:37	Chouser	yeah, wrap (float) around the whole thing or a divisor
09:37	glarf	ok just (float var)
09:44	Chouser	I think count-all-words could be just (map #(count-word % lst) set)
09:48	glarf	correct, vn
09:49	danlarkin	haskell-like?! more like prolog-like
10:07	Chouser	glarf: and I think count-words could be: (reduce (fn [occ w] (if (> (count w) 4) (assoc occ w 1) (merge-with + occ {w 1}))) {} (split file " "))
10:10	glarf	is there a way to shorten the massive error-messages?
10:11	glarf	liek normally the first sentence says something useful, then there is 30 rows of stuff that doesnt tell me anything
10:11	Chouser	at the repl they're only one line
10:12	Chouser	when generated from code in a file, those other error lines are often helpful for figuring out what lines of code are involved.
10:14	glarf	chouser: count-words, hmm it doesnt give any errors and it the program works however the result is not the same, 0.71 in one case, 0.52 in the other, i will look into it
10:16	glarf2	or merge-with will add values for keys that are equal?
10:23	glarf2	for some reason your functiond eosnt ignore the short words
10:23	glarf2	(> (count w) 4)
10:25	Chouser	merge-with uses the given function to merge vals when keys are the same. The function I gave was +
10:26	glarf2	ah now isee the error
10:28	Chouser	note there are no longer any uses of first/rest, so no need to use your aliases.
10:33	glarf2	im switching toa cond within the reduce
10:33	glarf2	how do i do with else.
10:33	glarf2	when the word is shorter than 4 chars i dont want to do anything
10:34	Chouser	:else occ
10:35	glarf2	yes
10:36	lisppaste8	glarf pasted "count-words" at http://paste.lisp.org/display/68103
10:37	glarf2	still a little bit shorter
10:38	Chouser	ah, I see what I misunderstood about your algorithm.
10:41	lisppaste8	Chouser annotated #68103 with "filter instead of cond" at http://paste.lisp.org/display/68103#1
10:49	blackdog`	with svn should i not be able to say (supers {}) as map implemetns java.util.Map now?
10:51	glarf2	chouser: isnt that inefficient though, it goes over the list once to filter and another to reduce right?
10:51	wwmorgan_	blackdog: try (supers (class {}))
10:51	blackdog`	ah
10:51	blackdog`	thanks
10:57	Chouser	glarf2: O(n) either way, and since filter is lazy, each word is getting the size check then the reduce step before the next word is taken.
10:58	Chouser	I bet it's comparable, but feel free to run some time tests and see which is better.
10:59	glarf2	ok thanks is there something i have to think about or when combining map filter and reduce i can count on it being the same as doing it all within a for-loop in an imperative language
10:59	glarf2	anyway 2*O(n) is still slower than O(n) right?
11:00	glarf2	but as you said now they re both O(n)
11:02	gnuvince	If it's lazy, it should be pretty much the same performance.
11:02	Chouser	in yours, each word is looked up in occ before either assoc or size test. In mine each gets a size check, only long words go to merge-with. I'm not sure that's 2*the work.
11:04	Chouser	you'd really have to run some test to see which is faster, as there are several differences. Creating a little hash-map for merge-with might be more expensive in mine than the extra word lookup in yours, for example.
11:04	Chouser	I'd be surprised is the difference was much either direction.
11:06	glarf2	i was thinking in un-lazy reduce/filter/map iterating twice over the list
11:06	scottj	What's the recommended way to get an integer from a float?
11:07	wwmorgan_	scottj: rounding or truncating?
11:07	scottj	wwmorgan_: truncating
11:07	wwmorgan_	(int x)
11:08	scottj	oh, missed that in the docs. I was searching for integer
11:10	glarf2	is there a time-function?
11:10	glarf2	or how do you profile?
11:10	glarf2	with your watch? :)
11:10	Chouser	(doc time)
11:13	glarf2	ok that retuend instantly
11:13	glarf2	which shoudlt happen
11:13	glarf2	�m testing ona huge file
11:13	glarf2	took 20 seconds before
11:13	glarf2	took 0.03 msec with time...
11:14	Chouser	got the right answer?
11:14	glarf2	no, no answer
11:14	wwmorgan_	glarf2: your function is probably lazy. Wrap it in a doall
11:14	glarf2	"Elapsed time: 0.028774 msecs"
11:14	glarf2	user.run__2537@15c30f6
11:14	glarf2	(time run)
11:14	glarf2	run = (defn run [] (classify f1 f2 f3 50))
11:14	Chouser	try (time (run))
11:14	glarf2	ah ofc
11:28	glarf2	chouser: the one using cond is slightly faster
11:28	glarf2	13sec vs 14 sec
11:28	Chouser	ok
11:41	danlarkin	is java 1.5 the same as "Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.x)
11:41	danlarkin	why did they change the naming scheme :'(
11:45	Chouser	I think it is the same, and I have no idea. I think someplaces it's also called 5.0
11:48	scottj	I'm not seeing in the docs how to find the length/size of a collection. ?
11:48	Chouser	(doc count)
11:49	scottj	In this case rick is wrong. There are too many good words :)
11:49	Chouser	:-)
11:52	rhickey	size is relative, and may have units, length implies distance, not a good fit for non-sequences
11:53	rhickey	count is about number, and also is a verb
11:54	Chouser	rhickey: I can't find anywhere that ever inits the vector held inside LazilyPersistentVector. vestigal feature?
11:54	Chouser	oh, scratch that, I see it.
11:54	lisppaste8	rgr annotated #68103 with "ignore this" at http://paste.lisp.org/display/68103#2
11:55	glarf2	i never feel like i need macros, are they overhyped? when using imperative languages i miss higher order functions, but never macros
11:55	glarf2	reddit: http://items.sjbach.com/16/some-notes-about-clojure
11:56	Chouser	in my experience, one very rarely needs to write macros in any language that has them.
11:56	Chouser	I frequently want them in languages that don't (JavaScript!) but if they exist, someone probably already wrote the macro I want.
11:58	rhickey	they are quite important to keeping the size of Clojure's core down
12:00	scottj	What is the common functional way of doing two for loops, one inside the other?
12:00	Chouser	(for [a [1 2] b [3 4]] (list a b))
12:00	Chouser	returns: ((1 3) (1 4) (2 3) (2 4))
12:00	cemerick	Macros can be indispensable in a domain-specific setting.
12:15	Chouser	right -- when you need them, there's no substitute.
12:53	scottj	Anyone else running ubuntu? Is the blue text near the bottom of http://clojure.org/reader hard for you to read? I'm wondering if it's just something on my computer setup or if the style for the examples in the docs might be hard for lots of linux users
12:54	scottj	It is much easier to read on my Windows computer..
12:54	Chouser	scottj: ubuntu here -- the only blue text I see is the code snippet. looks ok to me.
12:56	blackdog`	how's clojurescript going Chouser?
12:57	blackdog`	still have steam? :)
12:57	Kerris2	hello, I need help with using the Repl with JLine
12:58	Kerris2	I've copied the contents of the jline folder into the clojure folder, but
12:58	Kerris2	java -cp jline-0.9.94.jar:clojure.jar jline.ConsoleRunner clojure.lang.Repl doesn't work :\|
12:58	Chouser	blackdog`: a bit -- as of last night, trying to fill in some missing pieces in PersistentList and LazilyPersistentVector
12:59	blackdog`	are you going to implement dosync and STM?
12:59	scottj	Chouser: does it look like http://www.mediafire.com/?zimewyqynny for you?
13:00	Kerris2	maybe it'll work if I add both to the classpath
13:00	Kerris2	got to go now
13:02	Chouser	scottj: mine looks a little darker to me.
13:45	blackdog`	would it be possible to add a print method to see an array of java strings? rather than this [Ljava.lang.String;@1465ca2 ?
13:45	kotarak	Try (seq array-here). Help me with the inspector.
13:45	kotarak	Helped...
13:46	blackdog`	yea, i'm doing it by converting to a vec right now, but at the repl it would be a bit nicer
13:47	blackdog`	i was thinking giving the print multi methods now it could be quite easy to do
13:49	Chouser	(defmethod print-method (Class/forName "[Ljava.lang.String;") [a w] (.write w (str "[" (apply str (interpose " " a)) "]")))
13:49	blackdog`	:) thought so
13:50	Chouser	I guess that's not really right.
13:50	blackdog`	works for ,e
13:50	blackdog`	me
13:50	blackdog`	very neat
13:51	Chouser	maybe:
13:51	Chouser	(defmethod print-method (Class/forName "[Ljava.lang.String;") [a w] (.write w (str "(into-array" (apply str (map #(str " \"" % \") a)) ")")))
13:51	kotarak	The right is probably to check for .isArray in the :default implementation. At least are Arrays handled like this eg. in nth.
13:51	blackdog`	first one was better :P
13:52	Chouser	kotarak: yeah, this one's pretty specific.
13:52	blackdog`	good enough!
14:13	glarfani	hi i started with the (considering my lisp-noobness) ambitious project of creating an object-system for clojure.
14:13	Chouser	yikes
14:13	glarfani	im not sure about gensyms
14:14	glarfani	symbol# right?
14:14	hoeck	glarfani: or (gensym)
14:16	H4nsX	is there a way to query a form for its class? the compiler seems to know anyway when it finds out the methods that can be called in a dot expression. is that information available to clojure programs, too?
14:16	kotarak	(class ...) maybe?
14:17	H4nsX	kotarak: that will give me the class of a value. i need to compile-time class so that my macro can introspect into it.
14:17	H4nsX	s/to/the/
14:17	rhickey	H4ns: (resolve 'java.util.HashMap)
14:18	H4nsX	rhickey: ah, cool. trying that, thanks!
14:19	eyeris	Could someone point me to the documentation for how to invoke clojure as a compiler?
14:19	eyeris	I can only seem to find the `java -cp clojure.jar clojure.lang.Repl`
14:19	kotarak	There is no .clj to bytecode-in-file compiler at the moment.
14:20	eyeris	Is there a "just compile and run this .clj" invocation?
14:20	eyeris	non-interactive
14:20	Chouser	clojure.lang.Script
14:20	kotarak	clojure.lang.Script
14:20	eyeris	Is there an echo in here? :)
14:21	kotarak	... echo in here? ... in here? ... here? ;)
14:21	danlarkin	wow the clojure REPL is forming a habit... I'm trying to tab-complete in my emails...
14:22	kotarak	With certain editors this might work...
14:22	H4nsX	rhickey: no, that don't work - i am propably mislead anyway. i wrongly assumed that the method lookup would happen at compile time, whereas it is propably clear that it happens at run time.
14:23	Chouser	H4nsX: if the object type is known at compile time, it is resolved then.
14:23	Chouser	if not, it's "reflection" and can be flagged with warn-on-reflection
14:23	H4nsX	Chouser: ah, ok. thanks. i'll play some more.
14:23	rhickey	H4nsX: I'm not sure what you are trying to do, but Clojure tries to avoid runtime lookup
14:25	rhickey	If you are trying to write a macro, resolve will give you the class, your macro may need to do some reflection if you are trying to auto-build wrappers, but the code it emits can avoid reflection
14:25	H4nsX	rhickey: i would like to have a more pleasant syntax for getters and setters and am thinking about i could implement that. something in the lines of (getp object :fieldName) and (setp object :fieldName value)
14:26	rhickey	you should look at bean
14:26	H4nsX	ok, will read up on resolve and bean, thanks!
14:26	rhickey	you could make a lazy version of bean
14:27	rhickey	(bean (java.util.Date.))
14:27	H4nsX	uh, that is cute.
14:28	H4nsX	maybe i can just use that for starters and make it lazy once i feel it hurting me.
14:28	H4nsX	(but my plan is to stay scalable to multiple cores, so it may never hurt me)
14:29	eyeris	Is there a repository of example code I can browse through?
14:30	rhickey	eyeris: there's the wiki, also: http://blog.thinkrelevance.com/2008/9/16/pcl-clojure
14:30	rhickey	and http://writingcoding.blogspot.com/2008/06/clojure-series-table-of-contents.html
14:31	rhickey	and clojure-contrib
14:31	rhickey	and boot.clj
14:31	eyeris	Thanks
14:31	hoeck	and boot.clj
14:31	hoeck	oops
14:31	shoover	There's a nice chunk of practical clojure in http://github.com/jochu/swank-clojure/tree/master
14:40	gnuvince	Chouser: just a followup on yesterday, the problem was definitely with my network, so fetching pages in my Clojure script is now much faster
14:40	Chouser	gnuvince: ok, good to know.
14:44	glarfani	cant i create a hash-map with a gensym-key or use gensyms outside macros?
14:45	cemerick	glarfani: (gensym) works fine outside of macros
14:45	Hun	what's a use for a hashmap with a gensym-key?
14:46	rhickey	glarfani: sure: (hash-map (gensym) 1 (gensym) 2)
14:50	lisppaste8	rhickey pasted "reader object literals" at http://paste.lisp.org/display/68112
14:50	rhickey	someone was musing about defining print-method for arrays, without read support it's not that useful
14:50	rhickey	also, for AOT compilation I'll need readable representation of more objects
14:51	Chouser	hey, my string printer kinda worked -- printed (into-array ...)
14:51	Chouser	but yours is, of course, better. :-)
14:51	rhickey	the paste is what I'm thinking about, would allow print-methods to target this generic constructor form
14:52	Chouser	would print now differentiate between hash-map and sorted-map (for example)?
14:52	rhickey	#<classname ctor args ...>
14:52	rhickey	Chouser: there might still be special handling for those
14:53	rhickey	these would be striclty literals - no evaluated args
14:53	rhickey	strictly
14:55	Chouser	looks pretty good to me. JavaScript knows how to "print" lots of things that the JVM doesn't, and I could drop those into this syntax pretty easily.
14:55	Chouser	I think.
14:56	rhickey	#[...] would get evaluation support, like the built-in collections
14:56	rhickey	making it easier to call Java variadics
15:00	chmu	hi, is it possible to add metadata to structs? (with-meta (create-struct :x :y) { :mymeta 123 }) doesn't work (IncompatibleClassChangeError)
15:00	Chouser	is there something that prevents Java variadics from being supported directly?
15:02	Chouser	chmu: you can put metadata on a struct map
15:02	Chouser	(defstruct coord :x :y) (with-meta (struct coord 1 2) {:mymeta 123})
15:03	chmu	Chouser: I would like to add metadata to the "type" and not to the instance.
15:04	chmu	Chouser: Specifically I would like to add "type information" to members
15:05	rhickey	Chouser: the problem with supporting variadics directly is you can't tell, when being passed an array arg, if that is intended to be the entire set of variadics or simply first of one - in Java you use type casts to help the compiler
15:06	Chouser	rhickey: oh, type casts on the calling side? bleh.
15:06	rhickey	right, bleh
15:06	rhickey	chmu: right now those struct basis objects are opaque
15:07	Chouser	that's interesting, though, because I think I'm supporting them fine in JavaScript.
15:07	chmu	rhickey: Ok, maybe I should define my own "struct" then?
15:09	rhickey	chmu: you could always stick the basis object inside something else which held your extra data, then define a constructor fn that encapsulated that
15:10	glarfani	i want to make a function assoc! that : (assoc! some_map "hello" 12) -> (def some_map (assoc some_map "hello" 12)). but when i do as that i am returned a new map even if deffing to the variable passed
15:10	glarfani	do i need to use a macro or this is clojure immutabilti?
15:10	chmu	rhickey: ok, thanks
15:10	chmu	rhickey: I also tried to associate metadata with the symbol but ran into a problem with macros and metadata
15:10	chmu	rhickey: (defmacro create-bla [name val] `(def #^{:Some :MetaData} ~name ~val))
15:11	chmu	Metadata can only be applied to IObjs
15:11	rhickey	chmu: you have to understand the macro output will not be re-read, what you are trying to emit there is reader syntax for metadata - you could instead (with-meta...) the name symbol itself
15:12	rhickey	see defn in boot.clj
15:13	chmu	rhickey: Alright, so its not possible to "escape" the metadata construct?
15:14	rhickey	chmu: once your are defining the macro reading is over, but code is data and you can produce a form with metadata certainly
15:14	rhickey	glarfani: I'm not sure anyone will help you do that - what you are trying to do is very much not in the spirit of Clojure
15:15	chmu	rhickey: thnx
15:16	gnuvince	rhickey: does Clojure allow the creation of reader macros?
15:17	rhickey	gnuvince: not so far, and not likely until I figure out how to make them interoperate. Unlike regular macros there are no namespaces to prevent clashes between two sets of reader macros
15:17	gnuvince	ok
15:18	rhickey	of course I could have used up all the good characters by then :)
15:18	glarfani	rhickey: lol ok but im playing with clojure to learn more than anything else. learn about lisp, macros, language design etc.
15:18	Chouser	glarfani: you could write a function that does something like that on a ref
15:19	Chouser	but just because you can doesn't mean you should.
15:19	rhickey	glarfani: you'll learn the most by trying to avoid doing that :)
15:25	Chouser	rhickey: would you prefer posts with patches to have "PATCH" in the subject or something? Or would that just be ..um... bait.
15:43	Chouser	rhickey: there are a few things that could be Reversible that aren't (ArraySeq, StringSeq, Range, maybe others).
15:43	Chouser	Is that on purpose or just because rseq's not likely to be needed on those.
16:01	gnuvince	rhickey: do you think it would be do-able/reasonable to auto-escape backslashes in regex literals? Being able to write #"\d" instead of #"\\d"
16:03	Chouser	gnuvince: this has been discussed at length, but the interested parties gave up before reaching a conclusion.
16:03	Chouser	(myself included)
16:04	Chouser	we should give it a good think and come up with a real solution.
16:04	abrooks	gnuvince: Unfortunately, the regex literals are parsed as Java strings. Departing from that MAY be the right thing but it's not a minor departure.
16:05	gnuvince	I admit that I haven't looked at the source code before suggesting this (not that it would help much, I don't know Java.)
16:05	Chouser	I really want to do better. Clojure controls the reader, so we should make regex less painful. But there are edge cases that need to be thought out.
16:06	Chouser	http://groups.google.com/group/clojure/browse_thread/thread/81b361a4e82602b7/0313c224a480a161
16:06	abrooks	Chouser: Right but there's the concern that a regex literal would look different from a string literal that is turned into a regex (or if they looked the same, they'd act differently). That would be yucky.
16:06	gnuvince	I'll read that tonight.
16:09	Chouser	heh. yeah. good luck. :-)
16:10	Chouser	seriously though, I suspect there's a nice clean solution in there, but we can't just suspect or suppose, we need to provide sufficient evidence.
16:10	Chouser	...and do it soon enough that rhickey will consider including what's bound to be a breaking change to the reader.
16:10	gnuvince	Indeed
16:11	Chouser	abrooks: hm, interesting, though it might be hard to get rich to give up more reader chars for regex. :-)
16:11	gnuvince	I don't dislike syntax when it helps, but gratitious additions are just bloat.
16:11	cemerick	I'd think that regex literals could be interpreted as "raw" strings, a la python...
16:11	abrooks	Would it be bad to have three regex syntaxes? I think Rich might balk.
16:11	gnuvince	cemerick: that would prevent somebody from using hex or octal literals
16:12	gnuvince	(though they could use (re-pattern "\xc3")...)
16:12	cemerick	gnuvince: yeah, that's quite the edge case compared to forcing everyone to type \\d
16:12	gnuvince	cemerick: I agree
16:12	Chouser	Java regex knows how to parse hex literals to mean matching only that char
16:12	Chouser	also octal literals.
16:13	Chouser	so passing those "raw" into the Java Pattern should Just Work.
16:13	Chouser	I think almost everything works out like this, but someone needs to do the grunt work to demonstrate there aren't nasty corner cases lurking.
16:15	abrooks	Chouser: You're right. Pattern still knows all of the escapes that you'd want to do as string escapes.
16:18	abrooks	Chouser: Currently Pattern.pattern() returns a string identical to the input: (. #"\\\\dfoo" (pattern))
16:20	abrooks	Chouser: I'm really torn here. The Java situation is really horrible. Needing to think about more than one escaping level at a time is painful and prone to error. Being out of parity with the printable string form would be bad as well.
16:21	Chouser	I'm not torn at all. I don't care what .pattern returns, as long as clojure prints the same thing it reads.
16:22	Chouser	In my opinion, the current syntax is not good at all. To match a double quote (single char) you currently have to write #"\\\""
16:22	Chouser	unacceptible.
16:23	Chouser	but we want to get it right once, and clearly #""" isn't going to work, so we have to work out the details
16:24	Chouser	hm, you strike that -- you can also say #"\""
16:25	abrooks	Chouser: ... right. :)
16:25	Chouser	...which just proves Java Pattern is actually helping us out here -- we can pass in \" as raw and Pattern will do the right thing for us.
16:26	abrooks	As long as a Clojure regex can display the string in the same form as a literal regex or a regex created from a string so user input regexes are the same as user displayed regexes are the same as progammer visible regexes, I'm cool.
16:28	Chouser	whee: (prn-str (str \\))
16:29	abrooks	Ack.
16:29	gnuvince	ouch
16:31	ozzilee	Chouser: Why isn't #""" clearly going to work?
16:33	ozzilee	Nevermind, I was thinking of something else.
16:33	abrooks	ozzilee: Which quote terminates the regex? Consider that #"" " foo" and #""" foo" are the same.
16:33	ozzilee	abrooks: Well, I was thinking of """This is a raw string"""
16:33	abrooks	Ah, heh. Gotcha.
16:35	duck1123	does anyone know why I'm getting the message "java.lang.Exception: Unable to resolve symbol: progn in this context (NO_SOURCE_FILE:1)" when I try to open slime?
16:36	Hun	old slime i guess
16:36	duck1123	I also see this: (progn (load "/usr/share/common-lisp/source/slime/swank-loader.lisp" :verbose t) (funcall (read-from-string "swank-loader:init")) (funcall (read-from-string "swank:start-server") "/tmp/slime.31791" :coding-system "iso-latin-1-unix")) which I think is the problem
16:36	Hun	progn is common lisp
16:36	danlarkin	as for raw strings, I like the way python does it... prefixing the string literal with a lowercase R
16:36	Hun	you need a head cvs to use it in clojure
16:37	danlarkin	so r"raw string", r'raw string', r'''raw string''' and r"""raw string""" are all the same, raw strings
16:37	ozzilee	#"""<([A-Z][A-Z0-9])\b[^>]>(.*?)</\1>""" looks ok to me.
16:38	duck1123	I'm running a version from git from 2008-10-04
16:38	Chouser	huh. "\\" works, (= (str \\) "\\") is true, but #"\\" breaks
16:39	Hun	duck1123: of slime and swank_clojure
16:39	wwmorgan_	Chouser: I think because \ is not a valid java regex
16:40	duck1123	Hun: the swank_clojure should've been from the same day
16:40	Chouser	ok, I think this may not be too bad.
16:40	Hun	then it might be your slime. it tries to load the common lisp sources in clojure (which obviously fails)
16:40	Chouser	(defn prptn [p w] (.write w "#\"") (.write w (.replace (.pattern p) "\"" "\\\"")) (.write w "\"\n"))
16:41	Chouser	That prints a Pattern using the proposed new syntax, just like abrooks wants.
16:41	Chouser	" and \ must be (and when printed, are) escaped with a \
16:42	abrooks	Chouser: Great -- but (.pattern #"foo") should return the right thing by default, IMO.
16:42	Chouser	everything else is raw and literal, and I think you can match anything.
16:42	Chouser	abrooks: can't, that's Java's method
16:42	abrooks	Is there a Pattern interface?
16:42	Chouser	but (prn #"foo") can be made to use the implementation of prptn.
16:45	abrooks	Chouser: Would it be reasonable for an arity-1 prptn just return the apropriate string instead of write()ing?
16:46	Chouser	replace "defn prptn" with "defmethod print-method java.util.regex.Pattern" to plug it in (and throughly confuse yourself as you now have a non-standard prn)
16:50	abrooks	By appropriate string, I mean the form that you'd use in the literal format, not the What Would Java Do string.
16:51	Chouser	abrooks: it would just be confusing, because the printer of the repl will stick a bunch of backslashes in there so it can be read by the current reader.
16:53	abrooks	Chouser: I'm now confused. I was assuming you were talking about the future modified reader which didn't require slashing everything to death.
16:54	Chouser	prptn writes out a string that a proposed future reader could just read.
16:54	Chouser	defining it today as a print-method allows you to use today's prn to print out these future reader strings.
16:55	Chouser	I thought you were asking for a prptn-1 that takes a single arg and returns a string -- this would not be useful today for the reason I gave.
16:57	abrooks	Chouser: I was asking for that but I wanted it for the future usefulness. Also for other things (str "My pattern -->" (prptn #"foo") "<--")
16:57	abrooks	prptn is probably not a useful name in that case.
16:58	Chouser	prptn is not meant to be a name that would ever be using in the proposed future clojure.
16:58	abrooks	Perhaps would be a separate function which would do what I want.
16:58	abrooks	Chouser: Ah. AH HA!
16:58	Chouser	you could use (prn "My pattern -->" #"foo" "<--")
16:59	abrooks	Chouser: Only if I wanted to prn it. If I wanted to do something else with it (such as stick it in XHTML or a database do other processing) I'd want a string.
17:00	Chouser	gah, well, then you'd probably get what .pattern produces. Why would you do that?
17:00	Chouser	no, if you want to represent code as data in a string, use prn
17:01	Chouser	or prn-str or whatever.
17:01	Chouser	(str [1 2]) ==> "<vector: - 2 items>"
17:12	persi	I it possible to compile and load .java files into closure?
17:12	persi	clojure/closure
17:12	Hun	you can just import classes
17:13	persi	does that work for iterative development?
17:13	persi	i.e. can I reimport?
17:13	Hun	haven't tried, but i think so
17:14	persi	thanks. will try.
17:14	Chouser	I don't think so -- once a class is loaded, I think it's done.
17:15	Chouser	which is part of why gen-class works the way it does, allowing you to swap in new method implementations even though Java doesn't let you actually change the class.
17:16	persi	darn.
17:16	persi	so not really any help for developing java code.
17:16	persi	really was hoping for a repl around my java library development.
17:16	Hun	bean shell?
17:18	persi	bean?
17:18	persi	i'm a lisper, not a java person.
17:18	Hun	ah, ok :)
17:18	persi	need to develop some java and just wished for iterative development.
17:18	persi	thought clojure could help.
17:19	Chouser	persi: it's a JVM restriction, I think.
17:19	Chouser	Maybe you could something with creating new classloaders on the fly or something, but that's all over my head.
17:20	persi	Chouser: yea, figured that much. just going to go back to the stoneages of compile run rinse-repeat.
17:24	kotarak	persi: as long as you handle your object from clojure, you could do (YourClass-possible-method your-obj with some args). When you are satisfied, create a corresponding gen-class and its available from Java.
17:30	persi	katarak: But i'm developing a .java and using javac to make a .class. Can I do what your saying with this?
17:30	persi	kotarak: But i'm developing a .java and using javac to make a .class. Can I do what your saying with this?
17:31	kotarak	Probably not. But why do you need Clojure then? My idea was: create a Java class via gen-class. If you have a new method, but are not sure, test from the clojure side as described. Then finally add the definition of the method to gen-class call and it is available.
17:56	scottj	Is there a function I'm missing that's like (first-that pred coll) and returns the first value in coll that satisfies the predicate?
17:58	Chouser	(doc some)
18:00	wwmorgan_	some is slightly different: it returns the first true value of (map pred coll)
18:01	wwmorgan_	scottj: I think the best you can do is (first (filter pred coll))
18:02	duck1123	we need a clojure bot in here like what fsbot does in #emacs
18:02	Chouser	wwmorgan_: ah, good point.
18:03	scottj	I think first-that could be written as a macro by wrapping the predicate in an if that returns the arg if true
18:04	Chouser	wouldn't need a macro, just wwmorgan_'s code
18:04	wwmorgan_	yeah, laziness saves the day there, you fall out at the first true result
18:04	Chouser	yup
18:04	scottj	wwmorgan_: even if your collection is not lazy?
18:05	wwmorgan_	scottj: right, because filter is lazy
18:05	scottj	oh cool
18:11	duck1123	is there an easy way to add a folder to the classpath within clojure?
18:11	Chouser	(doc add-classpath)
18:13	duck1123	thanks, I must have missed that one
18:13	Chouser	np
18:14	scottj	Chouser: after running that should (. System (getProperty "java.class.path")) return anything different?
18:14	Chouser	scottj: not sure -- I wouldn't be surprised if it didn't. I think it changes the classpath of some other classloader.
18:16	scottj	ok, I don't think it changes
18:17	duck1123	I'm not seeing it change
18:18	Chouser	but does it work?
18:18	Chouser	as in, can you load the class you want?
18:53	scottj	From a basic clojure setup what has to be done to use psummary and inspect-table? I tried the following but it gives a class not found exception I think on ParallelArray (I'm not sure if slime modifies the error messages)
18:53	scottj	(ns foo (:require [clojure.parallel :as par]) (:use clojure.inspector)
20:32	rntz	is there some sort of searchable documentation for clojure? (like hoogle for haskell)
20:45	rhickey	rntz: there's (find-doc "regex string"), also http://clojure.googlegroups.com/web/manual.pdf
21:09	rntz	rhickey: thank you