#clojure – 2008-10-06

2008-10-06

01:23	sawjig	does gensyms protect from all potential evil of macros?
01:23	sawjig	like shadowing other variables and such?
01:24	sawjig	also, where can i find the source code for "builtin" macros like when and when-not?
01:25	blackdog	boot.clj for your second question
01:28	sawjig	ty
01:57	sawjig	is the use of backquoe discouraged in clojure? i see in boot hickey uses (list form) a lot, not graham-style macros
02:29	Lau_of_DK	Morning gents
02:29	Lau_of_DK	Can somebody direct me to the simplest approach to making an executable .jar file with Clojure code in it?
02:59	yangsx	H4ns: can you send manual.pdf to me? I'm unable to download any files from the clojure group :)
03:24	Lau_of_DK	blackdog down, you in ?
03:25	sawjig	is there no string-libraries in clojure?
03:26	sawjig	if wanting to work with strings, what is the best way?
03:27	sawjig	and how do i set default indent to 4 chars?
03:28	Lau_of_DK	Cant you use Javas stringmanipulation routines?
03:37	sawjig	how can i do multiple-value-bind?
03:38	Lau_of_DK	can you give an example of what youre trying to accomplish? mvb doesn't ring any bells with me
03:45	sawjig	user=> (def spam #{:egg 12, :ham 4}) #'user/spam user=> spam
03:45	sawjig	#{4 :egg 12 :ham}
03:45	sawjig	user=>
03:45	sawjig	when i do (get spam egg) i get an error
03:46	sawjig	(get spam :eqq) returns :egg not the value
03:52	sawjig	noone used Maps?
03:54	Lau_of_DK	user=> (def spam (hash-map :egg 12 :ham 4))
03:54	Lau_of_DK	#'user/spam
03:54	Lau_of_DK	user=> (get spam :egg)
03:54	Lau_of_DK	12
03:54	Lau_of_DK	#{} gives you a HashSET and not a map
04:00	Lau_of_DK	You can check your constructs with (class spam), which would tell you its a persistantHashSet
04:22	sawjig	http://hpaste.org/10933
04:22	Lau_of_DK	Has anybody here got an idea of how to implement a ListSelectionEvent ?
04:23	sawjig	why is splitall not splitting more than once? try (splitall "hellola" \l)
04:26	Lau_of_DK	I think you need to place (recur) within a loop or for statement
04:29	Lau_of_DK	(nevermind about the listener)
04:46	sawjig	http://hpaste.org/10934
04:46	sawjig	still not working
04:57	sawjig	i thought clojure supported polymorphism, why not + for cons?
05:00	sawjig	i am trying to add some stuff in boot.clj, do i ahve to recompile it then? because after i have done so i cant use it in the repl
05:01	sawjig	or i ahve to add it in some other file too?
05:37	leafw	sawjig: use user.clj
05:53	sawjig	leafw: where is user.clj? cant find it in src and not src/jvm
06:21	leafw	sawjig: you create it. And put it in whatever you want. Place it in the instantiation directory.
06:22	leafw	s/it in /in it/
06:22	Lau_of_DK	Can someone here point me to some info that will let me create an executable .jar file with clojure code in it ?
06:31	Lau_of_DK	Can someone here point me to some info that will let me create an executable .jar file with clojure code in it ?
06:33	sawjig	is the instantiation dir /src or just /clojure?. clojure.jar is in /clojure but boot is in /src
06:36	sawjig	dont i have to point something to this file? or is user.clj looked for by the interpreter automatically?
06:36	sawjig	ah wow it worked
06:37	sawjig	i put it in /clojure
06:38	hoeck	sawjig: it must be somewhere in the classpath
06:40	leafw	Lau_of_DK: user jar cf MyThing.jar my_script.clj MyMainClass.java , where the main class launches an interpreter that reads the clojure scripts included in it.
07:32	Lau_of_DK	Im not getting the .jar setup, rhickey, is there a place where I can put my main .clj in clojure.jar to make that file executable so that it fires up my program ?
07:43	sawjig	http://hpaste.org/10941
07:44	sawjig	how do i do if i want python-like ifs?
07:44	sawjig	like if his is true do that and have several ina row
07:44	sawjig	when doesnt help here, i dont want to nest
07:46	rhickey	sawjig: are your tests exclusive, or do you want them all to run?
07:46	sawjig	i want all to run
07:46	rhickey	and if they pass you want a side-effect?
07:48	Lau_of_DK	rhickey, did you catch my question about .jar?
07:48	rhickey	Lau_of_DK: user.clj will be loaded by default
07:49	sawjig	user.clj is very nice, i like how to open and hackable clojure is.
07:49	sawjig	rhickey: yes i want a sideeffect then
07:49	sawjig	i mean i could to this, but not in a clean way
07:50	sawjig	if could nest a hwole bunch of ifs i guess
07:50	sawjig	but thats not very clean
07:51	rhickey	sawjig: http://groups.google.com/group/clojure/msg/f7a1b33e2886008c
07:55	sawjig	thanks rick
07:57	sawjig	could you perhaps have a quick look at http://hpaste.org/10943 and tell me why splitAll doesnt work?
07:59	rhickey	what is it supposed to do?
07:59	rhickey	at first glance I can say if you are using reverse you are probably not leveraging Clojure's data structures
08:02	rhickey	there's only one call to reverse in boot.clj and it's not to fix up a recursive return value
08:03	rhickey	also please paste for this channel here:
08:03	rhickey	lisppaste8: url
08:03	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
08:12	lisppaste8	qwer pasted "tiest" at http://paste.lisp.org/display/68037
08:12	sawjig	^^
08:32	lisppaste8	hoeck annotated #68037 with "split" at http://paste.lisp.org/display/68037#1
08:42	Lau_of_DK	rhickey, practically speaking, how do I add my user.clj to the clojure.jar file ?
08:56	Lau_of_DK	isnt there a flat-map or flatten function in clojure ?
08:58	sawjig	isnt (defn f [& x]...) meaning optional params?
08:58	sawjig	or it is multiple?
08:59	cemerick	Lau_of_DK: try mapcat
08:59	Lau_of_DK	cemerick , thanks
08:59	cemerick	sawjig: there are no optional params, & x indicates rest parameters, and the name that the rest of the parameters are bound to within the fn
09:00	Lau_of_DK	cemerick , mapcat did the exact trick, thanks alot
09:00	cemerick	Lau_of_DK: np
09:36	rhickey	ok - maps are now Maps
09:37	drewr	Awesome!
09:37	drewr	That's going to greatly simplify some serialization code I've written.
09:38	rhickey	it was a pretty extensive change, so let me know if you encounter any glitches
09:38	drewr	Will do.
09:41	sawjig	can i raise an error somehow? define my own?
09:41	drewr	sawjig: (throw (Exception. "msg"))
09:41	drewr	You can subclass java.lang.Exception too, of course.
09:53	Chouser	clojurescript/avoid-java-in-boot.patch is now updated to work with the latest clojure svn
09:54	rhickey	Chouser: ok - that was fast!
09:54	Chouser	:-) git auto-merges pretty well.
10:06	sawjig	what is the point with conj? isnt it just (conj b a) instead of (cons ab) ?
10:07	sawjig	can i cons to the end of a list somehow?
10:07	Chouser	conj is polymorphic -- when used on a vector, it adds on the end.
10:07	Chouser	when used on a list, it's just like cons
10:08	Chouser	you can also use conj on sets and hashes
10:09	Chouser	http://clojure.org/data_structures click on "Collections" in the table of contents
10:09	sawjig	ok cool
10:09	sawjig	hickey said before he only used reverse once in the implementation of clojure. but i find myself needing to reverse a lot when using recursion
10:09	sawjig	is that bad technique then or is there some way to cons to the end?
10:10	rhickey	sawjig: if you use vectors your data will be in the right order
10:10	Chouser	if you're using lists and reverse a lot, there's a good chance you can use vectors and not need to reverse -- will be faster and less code
10:19	sawjig	well im working on lists and strings and need to return the same type that was passed...
10:21	Chouser	I hardly ever use lists in clojure. are you sure you need to?
10:21	Chouser	even so, you could build a vector while recursing and convert to a list (or seq) before returning it.
10:42	sawjig	does that create the same performance-penalty?
10:42	sawjig	as reversing
10:44	lisppaste8	sawjig pasted "reversing" at http://paste.lisp.org/display/68046
10:45	sawjig	some examples ^^ using reverse
10:46	drewr	What's tl?
10:46	cemerick	sawjig: no -- creating a seq from a vector is essentially free, whereas reversing a list is O(n)
10:48	sawjig	tl=tail=first,hd=head=rest
10:48	sawjig	cemerick: ok thanks ill use that instead then
10:49	drewr	sawjig: Yeah, but what is the symbol "tl" in your code mean?
10:49	drewr	Did you redefine rest?
10:50	sawjig	it means rest
10:50	sawjig	i defined it in user.clj
10:50	sawjig	because i hate writing long names...
10:50	sawjig	(defn tl [xs] (rest xs))
10:50	drewr	OK.
10:50	drewr	I would use idiomatic Clojure instead though.
10:51	sawjig	yes renamed it, rest is still there. i know some might hate that but i like them to have equal length(liens up nicely) and be short sinc eu use them so much
10:51	H4ns	very hard to get code reviewed which uses a different vocabulary.
10:51	Chouser	I pretty rarely use first or rest, either. Between destructuring and high-order functions, I rarely need to type out "first" and "rest"
10:51	sawjig	yes true
10:52	sawjig	ok illkeep thta in mind, im a lisp-noob so i prob write some primitive and dumb stuff
10:52	H4ns	sawjig: first off, do not redefine the vocabulary. get an autocompleting editor if you hate typing things too often
10:53	drewr	sawjig: Read boot.clj.
10:53	Chouser	sawjig: no worries -- people around here are generally quite willing to help if you're willing to learn.
10:53	H4ns	sawjig: second: don't try to optimize until you know what you need to optimize
10:53	cemerick	sawjig: it's just a matter of learning the idioms -- not really a question of dumb or primitive
10:55	abrooks_	Hrm. 63 of the files in Subversion have *nix (LF) style EOL, 52 have DOS (CRLF) style EOL. I noticed this while looking at the recent rev 1052 diff which spans a lot of files.
10:56	abrooks_	We should probably set svn:eol-style native on all the source files.
10:57	Chouser	sawjig: drop-last is already in boot.clj -- doesn't it complain when you try to def it?
10:58	Chouser	anyway, you might want to look it up in boot.clj; it doesn't use reverse
11:03	sawjig	drop-last isnt in boot clj but i have clojure_20080612, has it been added lately? i downloaded some time ago but havent played with it until now
11:04	sawjig	H4ns, i can add auto-completing in emacs right?
11:05	H4ns	sawjig: yes - M-/ completes something that you typed, considering all currently loaded buffers. that is enough for me, but you can allso set up explicit completion dictionaries. never did that.
11:13	Chouser	sawjig: latest release is 20080916 or you can use svn
11:17	tom`	hi all, I'm trying to get clojure working with slime, but I keep getting NoClassDefFoundError
11:18	drewr	tom`: While doing what?
11:18	tom`	swank-clojure-jar-path is set to the location of clojure.jar
11:18	tom`	starting slime (M-x slime)
11:18	H4ns	lisppaste8: url
11:18	lisppaste8	To use the lisppaste bot, visit http://paste.lisp.org/new/clojure and enter your paste.
11:18	tom`	I can paste-bin the inferior lisp output if it'llhelp
11:19	drewr	tom`: If you start slime with M-- M-x slime, can you choose clojure as your dialect?
11:19	lisppaste8	H4ns pasted "Clojure related section from my .emacs" at http://paste.lisp.org/display/68049
11:20	sawjig	howdo i turn [(\h \e \l \l) (\o \space \t \h \e \r \e)] back into a string?
11:20	lisppaste8	tom pasted "problem starting slime, inferior-lisp output" at http://paste.lisp.org/display/68050
11:20	H4ns	tom`: that, with path strings tweaked to suit, works for me on windows, macos, freebsd
11:20	lisppaste8	drewr pasted "My SLIME config" at http://paste.lisp.org/display/68051
11:20	Chouser	sawjig: (map str thing)
11:20	H4ns	tom`: with swank-clojure from git, cvs slime and svn clojure
11:21	tom`	H4ns: I'm using all those, clojure starts fine when I run it from shell
11:21	tom`	I'm on Ubuntu if that makes any difference
11:21	Chouser	sawjig: oh, or maybe (map #(apply str %) thing)
11:22	H4ns	tom`: from looking at the error message, i'd say the path to your clojure.jar is not correct
11:22	tom`	drewr: Yes, it's the only option right now
11:22	H4ns	tom`: i'm using swank-clojure-binary because i have some additional classpath settings to make and want to use the same settings on the shell and with slime.
11:22	tom`	H4ns: I've verified that is correct (and fully expanded using expand-file-name)
11:23	tom`	will try swank-clojure-binary
11:24	drewr	tom`: I use a custom version of http://github.com/jochu/clojure-extra/tree/master/sh-script/clojure.
11:25	sawjig	in cl i cn do (reduce '* '(1 2 3)) -> 6, can i do something like that in clojure instead of suing (fn[...)
11:25	tom`	I've just set it to a sh script containing "java -cp clojure.jar clojure.lang.Repl src/clj/clojure/boot.clj" which is the line I use to boot it from the command line
11:25	drewr	sawjig: user> (reduce * [1 2 3])
11:25	drewr	6
11:25	sawjig	ok but on a list?
11:25	drewr	user> (reduce * '(1 2 3))
11:25	drewr	6
11:26	sawjig	hey wtf i thought i tried that lol
11:26	drewr	Clojure's a lisp-1, so you don't have to quote the function.
11:26	tom`	ok, I set swank-clojure-binary to that script but I still get the exact same error which seems a bit odd. Do I have to do anything specialto make it use swank-clojure-binary
11:27	drewr	tom`: OK, that's fine. Do you change to the clojure directory before that command?
11:27	tom`	drewr: good point, that'll be it won't it. Let me just go fix that
11:28	drewr	cd /path/to/clojure && exec java -cp ...
11:29	H4ns	i'd rather use an absolute path for the jar and let clojure start in whatever directory i'm currently set to in emacs.
11:29	sawjig	drewr: is there scanl (=scanleft = reduce and return all the intermediate values)
11:30	drewr	H4ns: I would too.
11:31	drewr	sawjig: Like Haskell's? http://www.zvon.org/other/haskell/Outputprelude/scanl_f.html
11:31	sawjig	yes like haskells
11:32	sawjig	i wrote it,poste d before, just wondering if it wad there already, scan/dorun does soemthing else
11:32	drewr	I'm no functional prog expert. How is scanl different from map?
11:33	tom`	I switched to using the clojure startup script from the coljure-extra git
11:34	tom`	I can now run it using ~/clojure/clojure from any directory and it works fine
11:34	tom`	but I still get the same error in slime :(
11:34	drewr	C-h v swank-clojure-binary
11:35	H4ns	tom`: are you sure that your script is executed when you start slime in emacs? did you restart emacs?
11:35	sawjig	(drewr: scanl is reduce and all the intermediate values
11:35	sawjig	so (scanl + 0 '(1 2 3 4)) -> (1 3 6 10) or (0 1 3 6 10)
11:36	drewr	Ooh, this is cool: http://www.haskell.org/hoogle/?hoogle=scanl.
11:36	tom`	H4ns: will try retstarting emacs now, I was just shutting down slime then reloading
11:36	drewr	We need a Cloogle!!
11:36	tom`	back in sec (accessing irc via emacs)
11:36	sawjig	how do i convert from vector to list?
11:37	drewr	sawjig: (apply list [1 2 3])
11:38	H4ns	tom`: works now?
11:38	tom`	yep, restarting emacs did it
11:38	tom`	thanks for the help
11:38	H4ns	tom`: good. i spent the last 10 days wrestling with these kinds of issues, so i can feel the pain :)
11:38	tom`	bloody computers :p
11:39	drewr	Burn the lot of 'em!
11:40	tom`	how have you guys found the slime support in Clojure? I'm looking into it as a possible alternative to CL for a new project and slime is one of the most important factors (it's going to involve lots of exploratory programming)
11:41	H4ns	tom`: it works, but it is not as mature as cl support. i find it not so useful to explore whatever the platform provides, but that may not be an issue for you
11:41	H4ns	tom`: a real down side is the lack of support for 1, 2, *3
11:42	blackdog	new versions of clojure do havethat
11:42	blackdog	*1 etc
11:42	H4ns	blackdog: it is slime that does not have it, i think.
11:42	blackdog	ah ok
11:43	tom`	thanks, I'll carry on trying it out
11:44	H4ns	i'm not sure if M-. is supposed to work. i'm not at the point where i would miss it, but soon will be
11:44	tom`	I do like the look of Coljure, my biggest complaint about CL is that it's not enough of a functional style language
11:45	sawjig	how do i convert [ 1 2 3] to (1 2 3) and (\h \e \ l \l \o) to "hello" ?
11:47	blackdog	(apply str `(\h \e))
11:49	drewr	tom`: I think if you don't have much history with CL, then going with Clojure is a no-brainer.
11:50	drewr	If I was really productive in CL it would have been a much harder switch for me.
11:50	drewr	I'm your typical Lisper that ends up reaching for Python when he needs to get things done, but with Clojure I find I don't have to do that.
11:50	sawjig	how do i backquote on windows?
11:51	alec	tom`: Clojure and SLIME have worked well for me coming from a CL environment. It's not perfect, but it's good enough, and the swank-clojure maintainer is extremely responsive and helpful.
11:51	drewr	sawjig: What do you mean? Entering the backquote character?
11:52	sawjig	yes
11:52	sawjig	`
11:52	sawjig	ah
11:52	drewr	What's wrong with Windows?
11:52	sawjig	its not linux?
11:53	drewr	(That was a very contextual question. :-))
11:53	sawjig	so how do i convert from vector to list?
11:53	sawjig	(apply list...) doesnt work since list well lists things
11:53	danlarkin	sawjig: I think drewr means that backquoting on windows is the same as backquoting anywhere else
11:54	sawjig	well i found out how
11:54	drewr	sawjig: I don't know what you mean. (apply list [1 2 3 4]) => (1 2 3 4)
11:54	tom`	are there any good printable docs? All I can see right now is the wiki
11:55	drewr	tom`: There's a PDF in the Google Group.
11:56	tom`	thanks, didn't even know Google Groups had a file section
12:07	tom`	When I get an error in the slime repl it doesn't let me go into debug or even tell me which file the error is in, am I doing something wrong?
12:13	drewr	Yeah, since SLIME uses the clojure.lang.Repl, I think it can't figure out where the code occurred.
12:13	drewr	s/code/error/
12:16	tom`	doesn't that get really impossible? Not having a debugger is one thing, I can live with that, but not even knowing which file the error is in...
12:16	sawjig	why does rest [1 2 3] return the list (2 3) and no the vector [2 3] ?
12:17	drewr	sawjig: It's not a list. It's a vector that implements ISeq.
12:17	drewr	The seq abstraction is the key to much of Clojure.
12:18	drewr	tom`: Yes, it can get frustrating. That's one of the biggest shortcomings of Clojure right now.
12:18	sawjig	conj on a vector is O(1) right?
12:18	drewr	tom`: Although, Java people seem to do just fine with their tricks. I don't share their background.
12:21	tom`	that is a bit of a pity, I assume that it's quite hard to get that functionality working otherwise it would have already been done
12:21	tom`	that will probably be the clincher though, I think I'd go mad trying to cope with it
12:22	cemerick	while clojure error reporting isn't the greatest, I've never seen a situation where the stack trace doesn't pass through the offending code's file/line number
12:23	sawjig	(conj (rest [1 2 3]) 4) -> (4 2 3)
12:23	tom`	cemerick: I'm not getting a stack trace, is it just because I've got something set up wrong then?
12:24	drewr	tom`: No, that's not normal. I've found that some errors with swank have stopped producing stack traces. I think it's a bug.
12:24	drewr	Maybe not with clojure.
12:24	cemerick	tom`: I don't use emacs, but perhaps it's dropping clojure.lang.Repl's stdout/stderr on the floor?
12:25	sawjig	let [[h t] (split s delim)], is that patternmatching osmehow?
12:25	tom`	ok, that's not so bad then, any idea what I might be able to do to fix it?
12:25	cemerick	sawjig: yes, that's destructuring
12:25	cemerick	tom`: not a clue, sorry :-) I know there's some emacs users floating around, though.
12:26	tom`	I'll try the mailing list
12:30	sawjig	how can i get the typeof something?
12:30	rhickey	sawjig: (class x)
12:30	sawjig	lets say i have a function that takes a string lsit or vector and i want to return the same type that was passed so drop-last "hello" returns "hell" and not (\h \e \l \l)
12:32	sawjig	(apply (class "hello") '(\h \e)) results ina ne rror though
12:32	Chouser	sawjig: (\h \e) is probably a seq on a String. If you use the java methods of String, you'll get Strings back instead of seqs
12:33	rhickey	for types other than string, (into (empty x) (map f x))
12:33	Chouser	but if you don't want to do that, you can use (apply str '(\h \e))
12:33	rhickey	for string, you'll have to apply str to the result
12:34	Chouser	(class "hello") returns java.lang.String, which is not callable, so that's why it doesn't work with apply.
12:34	cemerick	rhickey: interface injection would eliminate that divide, yes?
12:35	rhickey	cemerick: maybe
12:36	rhickey	the problem is strings are not a persistent data structure - they are immutable but not persistent
12:36	rhickey	apply str uses a StringBuilder internally and is fast and efficient
12:37	rhickey	but treating strings like IPersistentCollections would have to full copy on write
12:38	cemerick	I've been working on digesting some of the "results" from the JVM summit of late.... :-)
12:39	lisppaste8	sawjig annotated #68046 with "scanl apply class" at http://paste.lisp.org/display/68046#1
12:40	sawjig	^^ (apply (class x) y) doesnt work though if y is a vector and x is a list
12:41	rhickey	sawjig: classes are not functions
12:42	sawjig	so how could i do what want without cheecking a whole lot of cases?
12:48	lisppaste8	Chouser annotated #68046 with "scanl via reduce?" at http://paste.lisp.org/display/68046#2
12:48	sawjig	and can i define + for strings?
12:51	sawjig	cool but now it still returns a list
12:52	sawjig	class clojure.lang.APersistentVector$Seq
12:52	Chouser	it returns a seq on a vector
12:52	Chouser	right
12:52	Chouser	how is that bad?
12:52	sawjig	actually but i cant conj to the end of it
12:53	sawjig	(conk (1 2 3) 4) -> (4 1 2 3) instead of (1 2 3 4)
12:53	sawjig	conj ^^
12:53	Chouser	right, you'd need a vector to conj on the end. Simplest is to wrap in vec: (vec (scanl ...))
12:54	Chouser	that's not the fastest, though, since it's building up a vector internally. You'd just have to rewrite it so it doesn't have the extra leading value (which I skipped using "rest")
12:54	sawjig	but why cant i have it return a vectoe if pass a vector?
12:55	Chouser	you can
12:55	sawjig	and i cant do (apply (class x) y) so i have t check if class x = someclass apply someclass y
12:55	Chouser	why do you keep trying to call a class?
12:56	Chouser	What do you expect it do to? Do you want (into (empty x) y) or something?
13:00	sawjig	if i do (scanl + 0 [1 2 3]) i want [1 3 6] back if i do (scanl + 0 '(1 2 3)) i want (1 3 6)
13:01	sawjig	ah yes into works
13:02	sawjig	oh well if i conjs to a list it get sreversed so it doesnt worka y way
13:03	Chouser	of course conjing onto a list reverses it, that's the direction that lists grow. If you didn't want it reversed, wouldn't you use a vector?
13:03	kotarak	Hmmm... What is the Sequential interface for?
13:03	Chouser	conjing onto a set puts things in random order. These are the features of the data strctures you're using.
13:05	sawjig	yes i know, im just thinking about a way to get what i want
13:05	Chouser	kotarak: http://clojure.googlegroups.com/web/chart.png
13:06	Chouser	kotarak: I think it just indicates if a collection is going to retain its order (like a vector) vs. not (like a set)
13:07	lisppaste8	rhickey annotated #68046 with "lazy scanl" at http://paste.lisp.org/display/68046#3
13:08	kotarak	Chouser: well, yes. I know this chart. But what is Sequential for? It's empty. I would expect seq() there (which is my understanding of "seq"uential). And an ISeq is not Sequential? I suspect a deep misunderstanding of ISeq on my side.... :(
13:10	Chouser	kotarak: well, there are things for which seq work that are not themselves sequential (like sets and maps)
13:10	rhickey	kotarak: it is a marker interface, all implementors indicate they are essentially sequential - i.e. lists, vectors, seqs
13:10	Chouser	But I am surprised ISeq is not Sequential, nor is IndexedSeq
13:11	rhickey	Chouser: they could be, all implementations of them are
13:11	Chouser	oh, IndexedSeq is just an interface, I see.
13:13	kotarak	Ok. A set is not Sequential, but a seq of a set is. When all seqs are Sequential, why is then ISeq not?
13:14	Chouser	kotarak: as rhickey just said, it could be -- all the classes that actually implement ISeq also implement Sequential.
13:14	kotarak	Just asking, because it caught be surprise.
13:14	rhickey	kotarak: that shouldn't matter, since you can only ask a concrete thing if it is sequential and they all are
13:14	rhickey	so would only be a convenience thing for implementors of ISeq - it has been requested
13:14	Chouser	hm, there are a lot of nested classes missing from that chart.
13:14	kotarak	I implemented a class with ISeq and it blew up with nth.
13:15	rhickey	there you go :)
13:15	rhickey	I'll fix, just a sec
13:15	kotarak	rhickey: :) geeshh... you are support in its essence. :)
13:17	rhickey	kotarak: it's up - rev 1053
13:17	kotarak	rhickey: cool, thanks. :)
13:17	rhickey	np
13:18	kotarak	Are there any plans to migrate other functions as nth, get, etc. to multimethods like pr?
13:19	rhickey	kotarak: probably not, for perf reasons since they are so primitive
13:19	rhickey	also I don't want the semantics to spiral out of control
13:20	rhickey	people have gotten some really bad habits from monkey patching in other languages I think
13:20	kotarak	ok. Would have been nice. (Did a test balloon with nth and it seemed to work fine, but performance should of course not be sacrifised....)
13:21	rhickey	Nice Clojure compliment from Cliff Click: http://groups.google.com/group/clojure/msg/241b23524bd585a1
13:22	Chouser	updated http://clojure.googlegroups.com/web/chart.png
13:27	kotarak	Oh. Btw, may I vote for gen-class to require the namespace, not the file directly?
13:36	scgilardi	regarding the idiom "(into (empty x) (map f x))", it works nicely in a lot of cases. One thing to watch out for is when it's applied to a list, the results are in reverse order from the original.
13:38	Chouser	sure, but if you peek and pop, you'll get things in the same order as you put them in, whether it's a list or vector.
13:38	pjb3	makes sense, assuming it is just conjing each item in the seq into the empty list
13:39	scgilardi	If it were abstracted into a function, perhaps subclases of Sequential could use a vector internally and then either return it or convert it to the input type as appropriate.
13:40	Chouser	but into also works on sets, sorted maps, hash maps ... I think you have to pick if you want polymorphism or not.
13:40	Chouser	If not, say (into [] ...) and get it in the order you want.
13:41	scgilardi	right, this came up in trying to write a polymorphic version. Whenever order doesn't matter (hash) or enforced by the data structure (sorted) or if it's a vector, the answer is unsurprising.
13:42	rhickey	scgilardi: I think no one should be surprised at things getting added to the front of a list - remember into works with a populated target as well
13:45	rhickey	so if I poured some more things into a large list I wouldn't expect them to be appended, with all the copying that would entail
13:45	scgilardi	right, I'm not criticizing into, just noting that when I first saw "(into (empty x) (map f x))" returns its result in the same type of container that it was give, I took it to mean that if "f" were "identity", I would get a result "=" to what was passed. That's almost always true, but not for list. Hence the "something to watch out for".
13:46	rhickey	scgilardi: I think it might be interesting to have ctor, like empty, that would return a corresponding contructing fn
13:46	rhickey	constructing
13:47	rhickey	(apply (ctor x) (map f x))
13:47	rhickey	or something
13:47	scgilardi	ah neat, yes that looks like it would work nicely.
13:48	rhickey	((ctor x) (map f x)) ?
13:49	scgilardi	right, that would be better I think. ctor takes seq and makes a collection from it.
13:49	Lau_of_DK	Evening gents
13:49	scgilardi	Heya, Lau
13:49	rhickey	scgilardi: might make a nice multimethod
13:50	cemerick	FWIW, 'ctor' isn't exactly common verbiage (though I love the idea)
13:50	rhickey	name suggestions welcome
13:50	Chouser	"new"
13:50	scgilardi	hehe
13:51	rhickey	Chouser: but it returns a fn
13:51	Chouser	ah, good point.
13:52	rhickey	the problem with polymorphic new is it has to be reflection based
13:52	cemerick	init?
13:52	Chouser	foo.constructor returns a function that creates a new instance of foo's class. In JavaScript.
13:53	scgilardi	yes, "constructor" does have a strong prcedent for this role
13:54	scgilardi	(ctor is short for constructor in C++ circles)
13:54	rhickey	where I used to hang out, apprently :)
13:54	rhickey	apparently
13:54	cemerick	scgilardi: yeah, I discovered that not too long ago (not ever having been in the C++ pool)
13:55	scgilardi	rhickey: do you recall who wrote the "javadoc" function that (I think) I saw posted here?
13:55	rhickey	cgrand
13:55	cemerick	Given the necessary presence of the constructor notion in Java, I'd say that using "constructor" would be overloading the term too much.
13:55	scgilardi	cgrand: thanks for that. I think it's great. Please consider making it a contrib.
13:56	scgilardi	"factory" is possible.
13:57	cemerick	yeah, factory is good
13:58	scgilardi	gotta run. thanks
13:58	rhickey	but what if the default _did_ call the constructor (had to force myself to type that out) reflectively
13:59	cemerick	constructor isa factory?
13:59	Chouser	in Javaland, a factory is a static or instance method, completely different from a constructor, right?
14:00	cemerick	Chouser: virtually always static
14:00	cemerick	A constructor is really just a special method on an instance
14:01	dudleyf	ctor isn't just a C++ term
14:01	scgilardi	Chouser: right, and we're talking about a function here that given an exemplar, returns a new one of those. Hmmm, it's an empty-clone.
14:02	scgilardi	(ctor x args) could create the object and then call its constructor with the args
14:02	rhickey	scgilardi: not really, empty is that, this is a fn that makes an instance given stuff
14:03	scgilardi	(right
14:03	scgilardi	so it's a lot like "new", but takes an object instead of a class
14:03	drewr	Chouser: Thanks for the class diagram!
14:03	rhickey	I think it could take a class as well
14:03	Chouser	and returns a function instead of an object
14:04	scgilardi	right, ok.
14:04	Chouser	drewr: :-) sure
14:04	scgilardi	what does javascript call that? they do new by cloning something that exists, don't they?
14:05	dudleyf	scgilardi: I wish
14:05	rhickey	the more primary notion takes a class, as you could build the other from (ctor (class x))
14:06	Chouser	function Foo(){}; foo = new Foo(); foo.constructor == Foo
14:06	scgilardi	but there's a name for this kind of non-class-based object orientation... it escapes me at the moment.
14:06	dudleyf	prototype-based
14:06	Chouser	scgilardi: prototypes, but that's not what this is.
14:06	scgilardi	ok
14:07	scgilardi	thanks for the word. it doesn't have to drive me crazy not knowing it now.
14:08	Chouser	that has to do with inheritence, where instead of pointing to a parent class, your derived class points to a prototype -- an instance of the parent.
14:10	blackdog	"make" ?
14:11	scgilardi	I think if this new thing takes arguments and calls constructors, ctor or factory work. (ctor (class x)) looks a lot like "new (class x) [args]". As a special form, new could be overloaded to do this. any merit?
14:12	Chouser	if it's returning a function, "maker" would be more accurate than "make", while if it's actually calling the constructor perhaps "new" could work.
14:12	Chouser	...although my earlier mention of "new" was definitely meant as a joke!
14:12	rhickey	new has to map to actual constructors, and isn't extensible, this is a pseudo ctor - create something from a collection of other things, subject to interpretation as a multimethod
14:13	rhickey	I don't want people to start doing a lot of reflective construction
14:14	scgilardi	wouldn't the target class still need a constructor that accepts "a collection of other things" (in this case) or "other things" in general?
14:14	scgilardi	in C++ a copy constructor that accepts seq (in this case)
14:14	rhickey	scgilardi: all of the Collection classes already do, but if a multimethod you could do whatever you want
14:15	Chouser	you could insert a 1-second delay to discourage its over-use
14:15	scgilardi	:)
14:15	rhickey	reflection already does that, no?
14:15	Chouser	reflection + multimethod gets you close
14:16	rhickey	the point of using a multimethod is you could make it fast
14:16	rhickey	predefine for all collections and you might not need any others
14:16	rhickey	string version could use a StringBuilder internally
15:11	lisppaste8	gnuvince pasted "Slow string accumulation" at http://paste.lisp.org/display/68062
15:13	rhickey	gnuvince: see slurp in boot.clj
15:18	gnuvince	rhickey: (let [u (new URL "http://www.yahoo.com")] (slurp (. u openStream)))?
15:20	gnuvince	No, that doesn't work.
15:21	Chouser	gnuvince: I think he meant you can look at how it builds a string faster.
15:21	rhickey	gnuvince: I meant look at the source for slurp, slurp doesn't read from urls
15:21	gnuvince	OK.
15:25	Chouser	gnuvince: (apply str (line-seq (ds/reader (.openStream (URL. "http://www.yahoo.com")))))
15:26	Chouser	I got the ds namespace like this: (ns user (:require [clojure.contrib.duck-streams :as ds]))
15:27	Chouser	oh, you can actually drop the .openStream bit -- ds/reader will do that for you
15:30	gnuvince	I must be doing something wrong somewhere, because it takes 8 seconds to fetch 3 comics while my original Python program fetches 20 in 3 seconds
15:31	Chouser	huh, you can leave out the URL ctor as well: (apply str (line-seq (ds/reader "http://www.google.com")))
15:32	rhickey	don't you want a with-open in there?
15:32	Chouser	oh, I suppose I do.
15:33	Chouser	(with-open r (ds/reader "http://www.google.com") (apply str (line-seq r)))
15:34	Chouser	gnuvince: your python wasn't going in parallel or anything, right? :-)
15:34	gnuvince	Chouser: it was.
15:34	Chouser	oh, and your clojure is too?
15:34	gnuvince	Chouser: I'm trying to at least.
15:34	gnuvince	Can't say I'm succeeding
15:36	Chouser	gnuvince: you could stick some println's in, like before and after each page is fetched -- ought to be able to see whats in parallel, and perhaps where the delays are.
15:36	rhickey	get the with-opens in there or your connections aren't getting closed
15:39	gnuvince	rhickey: I did.
15:39	gnuvince	Followed the code of slurp almost verbatim.
15:40	rhickey	you aren't doing Chouser's line-seq stuff?
15:40	rhickey	apply str wraps all the stringbuilder junk
15:41	gnuvince	No, I don't have the contrib directory.
15:42	Chouser	Unless you know otherwise, I'd be suspicious of startup time -- some people have reported as much as 4 or 6 seconds in some configurations.
15:42	rhickey	everything except ds/reader is default Clojure, just put your reader there
15:43	gnuvince	Chouser: doing my testing in the REPL
15:46	gnuvince	Do you guys want to see the whole thing? I could be way off.
15:50	Chouser	gnuvince: feel free to paste it.
15:51	lisppaste8	gnuvince pasted "Comic fetcher" at http://paste.lisp.org/display/68064
15:56	gnuvince	How does that look?
15:57	scottj	Is clojure-contrib included in clojure or do you have to download it separately from its SF page?
15:57	abrooks	scottj: http://sf.net/projects/clojure-contrib
15:58	abrooks	(It's separate.)
16:00	wwmorgan	gnuvince: you might get better performance if you use the byte array input stream read methods instead of the single byte method
16:01	duck1123_	if I have a clojure script in a file that I execute using the shebang trick, does that compile it every time, or is something cached?
16:01	Chouser	you want send-off instead of send, since fetch-comic can block.
16:01	duck1123_	and if the former, can it be compiled for later use?
16:01	Chouser	duck1123_: compiled every time. There's currently no way to "cache" compiled clojure code.
16:02	scottj	abrooks: thanks. There are no installation instructions right?
16:02	Chouser	scottj: just unpack it somewhere and add clojure-contrib/src to your java classpath.
16:02	gnuvince	Chouser: is an agent the correct type of reference to use?
16:03	abrooks	scottj: Not that I'm aware of just use ant/mvn the same way you build Clojure and do what Chouser said.
16:03	abrooks	^of^of --
16:03	Chouser	you don't have to build clojure-contrib at all, afaik.
16:04	abrooks	Chouser: Really? Hm. I did.
16:04	abrooks	I guess you wouldn't have to. I build a jar and point my classpath to that.
16:05	abrooks	Much better to point to the live files though...
16:06	jao	has clojure an equivalent to scheme's letrec or cl's labels?
16:09	Chouser	jao: you can put a name a fn so: (fn foo [] ... (foo ...))
16:09	Chouser	hopefully the clojure makes sense even if my english didn't.
16:10	jao	Chouser, mutually recursive ones?
16:10	Chouser	gnuvince: yeah, I think an agent is fine
16:10	gnuvince	OK
16:10	Chouser	jao: no, that name is only good inside the fn
16:10	gnuvince	And I think the reason it is slow is that www.comics.com seems to load really slowly on this machine.
16:11	Chouser	for mutual recursion, I think you may need (def foo) (defn bar [] ...) (defn foo [] ...)
16:11	gnuvince	On another machine (with a different ISP), the entire source loads instantly
16:11	jao	Chouser, i see. thanks.
16:12	Chouser	gnuvince: using send instead of send-off means you were using a pool of threads sized based on your number of CPUs.
16:12	gnuvince	and with send-off?
16:14	kotarak	jao: but mutual recursion is not a good idea in Clojure due to the limitations of the JVM concerning TCO.
16:16	jao	kotarak, which is a pity :)
16:16	Chouser	send-off gets threads from a pool that grows as needed.
16:16	kotarak	jao: according to Rich a lot of people complained at the JVM Summit. Maybe there will be some change soon. :)
16:17	Chouser	kotarak: good point, although using lazy-cons or something similar can still require the (def foo) but not threaten the stack.
16:17	kotarak	Chouser: yep. have to work more with lazy-cons, me thinks...
16:20	Chouser	gnuvince: so you're happy with your code's performance now?
16:20	jao	(although i think mutual recursion would be useful even without TCO in some cases; after all, CL doesn't ensure TCO and has labels.)
16:23	gnuvince	Chouser: I'll try the code on my machine at home and see if it's indeed something with my workplace's network that's causing the delay.
16:28	Chouser	gnuvince: I don't think that's parallel. You're sending fetch-comic to the same agent, so it'll do them in series.
16:29	Chouser	you'd need a new agent for each fetch-comic, and probably a ref to help you coordinate the results.
16:29	gnuvince	agents to send-off x fetching threads and use commute to accumulate them into a vector?
16:30	Chouser	yeah, I think that would do it.
16:30	gnuvince	OK.
16:30	gnuvince	I'll look into it.
16:30	Chouser	(doseq c coll (send-off (agent nil) (collect-comic c))) or something
16:31	Chouser	where collect-comic would call fetch-comic and do the dosync commute stuff.
16:31	gnuvince	Is this channel logged on ircbrowser.net or something?
16:31	Chouser	http://clojure-log.n01se.net/
16:32	gnuvince	Good
16:32	gnuvince	thanks
16:32	gnuvince	In case I need to review this conversation.
16:33	wwmorgan	chouser: does (collect-comic c) belong in its own S-expression there?
16:35	wwmorgan	or would (doseq c coll (send-off (agent nil) collect-comic c)) make more sense?
16:35	Chouser	wwmorgan: nope, you're right.
16:36	Chouser	or perhaps (send-off (agent c) collect-comic)
16:49	scottj	gnuvince: I would be interested in seeing your finished code.
18:03	danlarkin	So in boot.clj (http://clojure.svn.sourceforge.net/viewvc/clojure/trunk/src/clj/clojure/boot.clj?revision=1052&view=markup) on line 1267 the filter function is defined. Why won't that blow the stack, since it will recurse without using recur
18:05	rhickey	danlarkin: that call is in a lazy-cons, which suspends the expression until needed
18:06	danlarkin	but when I evaluate it with a huge list doesn't it have to keep all that stack info around?
18:07	rhickey	danlarkin: there's no stack info, filter returns without that second call happening. Later, if someone calls rest, that call will be made, retuning another lazy cons. They don't build up on the stack, there is no recursion
18:16	danlarkin	ah ha, I think I understand. (rest (filter ...)) is a clojure.lang.LazyCons datastructure, it doesn't just call up the (cons..)
18:49	alec	I'm trying to get Lucene working from Clojure. There's a class Field.Index under org.apache.lucene.document, but when I (import '(org.apache.lucene.document Field.Index)), I get a class not found error. Fiddling with it a bit doesn't help me load the class, and I'm guessing it's the '.' in there. Any suggestions?
18:50	rhickey	Field$Index
18:50	alec	thanks, that worked!
18:51	alec	I don't see that on the Java interop page; is there somewhere else I should have looked?
18:52	rhickey	no, it's just a Java thing, that's the real JVM name for a nested class
19:49	lisppaste8	johnwayner pasted "gen-class with main issue" at http://paste.lisp.org/display/68077
19:51	johnwayner	I'm trying to figure out how to define a main for a gen-class, but I can't seem to get it to work.
19:51	johnwayner	I've tried looking through the gen-class function, but I can't quite figure out what the problem is.
19:53	johnwayner	Also, I was wondering if there's a reason gen-and-save-class doesn't create the directory structure. It seems simple enough which is why I think there must be a more compelling reason. (.. file getParentFile mkdirs)
19:53	johnwayner
19:53	Chouser	johnwayner: try (defn Test-main ...)
19:54	johnwayner	I tried that... But I'll try agin
19:54	Chouser	hm, not sure...
19:54	johnwayner	yeah, same result
19:57	Chouser	works for me
19:57	Chouser	no, something's screwy. hang on
20:04	Chouser	ok, I'm seeing your error.
20:04	Chouser	I don't think I've ever used :main correctly.
20:05	johnwayner	there's not much on the web that I could find
20:05	johnwayner	what do you see?
20:06	Chouser	exactly what you posted.
20:06	johnwayner	Ohhhhh
20:07	johnwayner	I thought you meant that you saw what I was doing wrong :)
20:07	Chouser	also I put (prn :loaded) in the .clj, and I'm not seeing that, so I don't think it's finding the .clj file correctly.
20:07	Chouser	ah, sorry. :-/
20:08	johnwayner	what do you mean by finding the .clj file? When does it do that? Does the class file need to find the clj?
20:09	johnwayner	If so, I've completely got the purpose of gen-class all wrong :)
20:10	Chouser	gen-class generates a little stub .class -- the implementation of each generated method just turns around and calls the clojure function in the .clj file.
20:10	Chouser	this allows you to swap out implementations at runtime, just like regular clojure functions.
20:10	johnwayner	hmmm....
20:13	johnwayner	jeez... it says that right there in the first paragraph of the doc string.
20:14	johnwayner	I've copied my Test.clj to the .class location but I'm getting the same result still.
20:14	johnwayner	I'm assuming that's what you did in the first place :)
20:15	Chouser	ok, :main is broken. But not broken enough to be causing your problems.
20:16	johnwayner	ha
20:16	Chouser	I honestly didn't know what it was for, so thanks for your example. :-)
20:17	Chouser	ok, so until gen-class is fixed, the name of the fn should be just "main"
20:17	Chouser	strike that
20:17	Chouser	gah, I'm confusing myself.
20:19	johnwayner	Thanks for your help. I've got to run for a while, but I'll check back later. Please just respond here if you come up with anything.
20:19	Chouser	"Test-main" is right, it's the error messages that are wrong.
20:19	Chouser	johnwayner: ok, np.
20:20	johnwayner	oh...I should try that now that I know that the clj is needed...
20:20	johnwayner	hey hey
20:21	johnwayner	airty issue...but it found the fn
20:21	Chouser	oh!
20:21	Chouser	well, you're ahead of me then.
20:21	johnwayner	got it
20:21	johnwayner	changed it to no args
20:22	johnwayner	I'll annotate.
20:22	lisppaste8	johnwayner annotated #68077 with "fixed." at http://paste.lisp.org/display/68077#1
20:23	Chouser	great, thanks.
20:23	johnwayner	thank you!
20:23	johnwayner	I was in left field with my thinking about all this.
20:23	johnwayner	Ok... gotta run.