#clojure – 2011-04-10

2011-04-10

00:11	danbell	I'm having trouble getting an example app to run through Tomcat;
00:12	danbell	since clojure compiles straight to bytecode, it's hard to make sense of the stacktrace
00:12	danbell	any general tips?
00:12	mec	would (eval `(~x ~@args)) be particularly slower than (apply x args)
00:14	livingston	mec: i dont' know about in clojure but there are other considerations such as lexical scope when using eval in commonlisp
00:14	livingston	is there a good reason not to use apply?
00:14	mec	x could be a macro
00:15	mec	well seems to be about 21 times slower
00:15	livingston	is it a function some is passing you? just make them pass you a function version or something.
00:16	amalloy	i've actually found a good (i think) reason to use that eval form, but in general it's a terrible idea
00:16	livingston	there's an expression "eval is evil" it isn't and the basis for the expression is bad, but in general it's best to avoid it.
00:16	livingston	same for macros, if there a reason to use them fine, but if a function fits, use that.
00:17	livingston	sure there can be plenty of good reasons. lazy is a bad one though ;)
00:17	amalloy	danbell: (1) look for entries in the stacktrace that contain myproj.myns. most of the interesting ones will look like that. (2) as with any java stacktrace, the "root cause" exception is often most related to your code. look for "caused by": the last instance of that is the root cause
00:18	danbell	amalloy, as usual, is ridiculously helpful
00:18	amalloy	there's also clj-stacktrace, which purports to make stack traces more readable
00:30	amalloy	mec: out of curiosity, what are the circumstances that make you want to use eval like that?
00:30	mec	playing around with findfn
00:30	amalloy	haha, that explains why you saw that eval form, i guess
00:30	livingston	I just tried to comment something out in java with a semicolon. it compiled I thought i was good then got really confused. (you can put as many extra semicolons in between statements as you want)
00:32	amalloy	while (x < 10);
00:32	amalloy	x++;
00:33	amalloy	the semicolon of doom
00:33	livingston	ok maybe not there. but that's your fault for not using squigglies
00:34	amalloy	livingston: well, that's not "in between statements", so your claim is still true
00:34	livingston	that's why sexpressions and prefix notation win again ;)
00:34	livingston	I guess that's true too
00:34	mec	,(apply #'and [1 2])
00:34	clojurebot	true
00:34	mec	why does that return true
00:35	amalloy	$source and
00:35	sexpbot	and is http://is.gd/pY0AD3
00:36	amalloy	&(#'and)
00:36	sexpbot	java.lang.IllegalArgumentException: Wrong number of args (0) passed to: core$and
00:36	livingston	lol
00:36	mec	weird
00:37	amalloy	mec: it's calling the function behind the and macro, with 1 as &env, 2 as &form, and no "actual" args
00:37	amalloy	&(#'and 1 2 3)
00:37	sexpbot	⟹ 3
00:37	amalloy	&(#'and false false 3)
00:37	sexpbot	⟹ 3
00:38	mec	crazy
00:39	livingston	,(macroexpand '(apply #'and [1 2]))
00:39	clojurebot	(apply (var and) [1 2])
00:39	mec	,(apply #'and nil nil [true true false])
00:39	clojurebot	(clojure.core/let [and__3468__auto__ true] (if and__3468__auto__ (clojure.core/and true false) and__3468__auto__))
00:40	mec	ok so i guess i'll stick with eval
00:40	amalloy	mec: you definitely won't get what you want by applying a macro
00:40	livingston	you're quoting a macro
00:41	amalloy	i guess that's not true. you might want crazy, unpredictable results
00:41	mec	i enjoy living on the edge
00:42	pdk	if you want crazy unpredictable results
00:42	pdk	try some c++ multithreading libraries
00:43	livingston	I have enough fun with java and it's dumb libraries, I don't need to go back to freeing memory too, thanks.
00:44	mec	i suppose it makes sense that the only way to expand a macro at runtime is with eval
00:45	livingston	macros are processed at read time. it doesn't know what to do if you try to fn'call one.
00:47	amalloy	livingston: otoh, they are just functions underneath, which is why ##(#'and nil nil x y) is the same as ##(macroexpand '(and x y))
00:47	sexpbot	((var and) nil nil x y) java.lang.Exception: Unable to resolve symbol: x in this context
00:47	sexpbot	(macroexpand (quote (and x y))) ⟹ (let* [and__3468__auto__ x] (if and__3468__auto__ (clojure.core/and y) and__3468__auto__))
00:48	amalloy	&(#'and nil nil 'x 'y)
00:48	sexpbot	⟹ (clojure.core/let [and__3468__auto__ x] (if and__3468__auto__ (clojure.core/and y) and__3468__auto__))
00:49	livingston	how do I ask an object what interfaces it implements?
00:50	livingston	amalloy: sure it's a function, but it's a function that returns code
00:50	amalloy	&(supers (class []))
00:50	sexpbot	⟹ #{java.util.List clojure.lang.AFn java.lang.Object java.io.Serializable java.lang.Runnable java.util.Collection clojure.lang.APersistentVector clojure.lang.Seqable clojure.lang.Indexed clojure.lang.Reversible clojure.lang.Sequential clojure.lang.IPersistentStack cloj... http://gist.github.com/912053
00:51	livingston	er, sexpressions really that are then stitched into the code
00:51	amalloy	or if you want to test implementation of a particular interface, ##(instance? Runnable [])
00:51	sexpbot	⟹ true
00:52	livingston	that got me what I needed. I need to see what interfaces where available on a clj object so that I knew what were my options to tell stupid-java to cast it to
00:52	livingston	thanks
00:52	ssideris	amalloy: wait, why is [] Runnable???
00:52	amalloy	ssideris: because it's a function
00:53	mec	,([1 2[ 0)
00:53	amalloy	&([1] 0)
00:53	clojurebot	Unmatched delimiter: )
00:53	sexpbot	⟹ 1
00:53	mec	doh
00:53	amalloy	haha clojurebot looks like he's laughing at you
00:53	ssideris	amalloy: thanks, didn't know that!
00:53	livingston	,(
00:53	clojurebot	EOF while reading
00:54	livingston	I was hoping to get him to frown
00:54	amalloy	&([1 2[ 0)
00:54	sexpbot	java.lang.IllegalArgumentException: Wrong number of args (0) passed to: PersistentVector
00:54	amalloy	heh
00:54	mec	lolwut
00:54	amalloy	sexpbot tries to clean up unbalanced expressions
00:54	amalloy	looks like the one he cleaned up caused some problems
00:55	amalloy	&(let [x 1) (inc x)
00:55	sexpbot	⟹ 2 ; Adjusted to (let [x 1] (inc x))
00:56	ssideris	so basically nth is only necessary for lazy sequences like ##(nth (range 10) 2)
00:56	sexpbot	⟹ 2
00:57	amalloy	ssideris: or for lists, or for cons chains, or for j.u.Lists, or...really anything but vectors
00:57	ssideris	ok
01:15	livingston	how can people program without repl? change, compile, run, damn, GOTO 10 ... this takes forever
01:23	mec	i dont know how i ever programed without doc and source
01:24	livingston	mec: show is the biggie for me in the repl
01:25	livingston	programming in java is for the birds though - of all things it just yelled at me for giving it too much type information. gah.
01:25	amalloy	haha clarify plz livingston?
01:26	livingston	amalloy: I had declared a variable and set it's value in one one line. then I copied it later (accidentally keeping the type declaration for the variable - which stayed the same) and it refused to compile it
01:27	amalloy	yeah, it's annoying to declare a variable exactly once, when you'd like to copy the assignment line or something. to be fair though, it's not objecting to too-much-type-info
01:28	livingston	I passed a clj list out to my java program and tried to call println on it but all I get is: clojure.lang.LazySeq@4e63d25f how do I print the list trivially in java
01:28	livingston	I know I know, but it looks like that. I mean c'mon if you are going to make me spoon feed you types at least cut me some slack
01:29	amalloy	livingston: try new j.u.LinkedList(theLazySeq).toString() maybe?
01:29	amalloy	i mean, even in clojure it's not "trivial" to print a lazy seq: ##(str (range 3))
01:29	sexpbot	⟹ "clojure.lang.LazySeq@7480"
01:29	livingston	how does the repl do it?
01:30	amalloy	&(pr (range 3))
01:30	sexpbot	⟹ (0 1 2)nil
01:31	livingston	,(str (seq (range 3)))
01:31	clojurebot	"(0 1 2)"
01:31	livingston	&(str (seq (range 3)))
01:31	sexpbot	⟹ "(0 1 2)"
01:32	livingston	?
01:32	amalloy	? ? ???
01:35	livingston	yep I cast it to ISeq and called .seq() on it and out it comes. Still doesn't seem elegant though.
01:37	mec	omg I think I finally understand monads. Now I must take the required sojourn into the forest to compose my own "what is a monad" tutorial
01:38	amalloy	congratulations, you now have permission to join the super-secret #clojure-awesome room
02:14	livingston	well good night and thanks everyone
02:48	Havvy	In Swank/Slime, how do you get it to tell you the line number the error was found on?
02:57	amalloy	Havvy: if it knows the line number, it tells you
02:59	zakwilson	Doing CPU-intensive things in Clojure on my laptop for long periods of time very reliably overheats my laptop unless I manually max-out the fan speed.
03:01	shachaf	function clj() { fanspeed max; clojure "$@"; fanspeed auto; }
03:01	Havvy	I haven't found the line number being shown yet in swank...usually shows it when there is no swank, but then I get classpath errors galore. :/
03:01	amalloy	zakwilson: are you objecting that, when you ask clojure to use your cpu, it uses your cpu?
03:02	shachaf	Clearly Clojure isn't CPU-efficient, which means the CPU heats up more than it does with other languages.
03:02	amalloy	Havvy: when there are exceptions during macroexpansion, iirc swank can't tell what line they're on
03:02	amalloy	or, at any rate, C-c C-k can't; if you eval just a single form instead of the whole file, that sometimes helps
03:02	zakwilson	Well... no, but I don't think I've seen as much heat generated maxing out the CPU with other languages. This may be because I spend a lot more time maxing out the CPU with Clojure.
03:03	Havvy	I'd love stacktraces to remove all of the invokes though. Pure noise to me...
03:03	zakwilson	I AM complaining that my laptop doesn't ever set the fan to full-speed automatically, but any more on that would be off-topic.
03:04	Havvy	Anyways, is there a recursive version of map and apply so that when it finds a collection, is goes into the collection and does its operation on that?
03:04	amalloy	Havvy: clojure.walk/{pre,post}walk are probably what you want
03:04	amalloy	or clojure.walk/walk if you need more fine-tuned operation
03:07	Havvy	Thanks.
03:23	seancorfield	map vs pmap question...
03:24	seancorfield	with map, operations only use 100% CPU on my quad core (therefore only one CPU) as i'd expect
03:24	seancorfield	with pmap, operations use 400% CPU (all four cores) as expected
03:24	seancorfield	however, pmap often takes LONGER to complete an operation than map
03:25	seancorfield	is the overhead on doing parallel operations really that high?
03:25	amalloy	seancorfield: split your task into fewer subtasks, each of which is larger
03:25	amalloy	(yes)
03:25	seancorfield	my test case was a slow function that did 1,000,000 operations internally
03:25	seancorfield	and map that over 100 elements
03:26	seancorfield	map took about 15 seconds every time
03:26	seancorfield	pmap took 5 seconds the first time but then longer and longer on each subsequent time
03:26	amalloy	eyebrow
03:26	seancorfield	so i assume i need more heap...
03:26	seancorfield	but, seriously, that was not what i expected :)
03:27	amalloy	what do you mean, "every time"? every 1M operations, or every 1M100 operationpartitions?
03:28	seancorfield	(dotimes [_ 10] (map expensive (repeat 100 1)))
03:28	seancorfield	that took 15 x 10 seconds
03:28	seancorfield	(map expensive (repeat 100 1)) takes 15 seconds
03:28	amalloy	okay
03:28	seancorfield	(pmap expensive (repeat 100 1)) takes 5 seconds on a clean jvm repl
03:29	seancorfield	but takes 10 seconds the second time, then 15 seconds, then 20 seconds
03:29	seancorfield	so (dotimes [_ 10] (pmap expensive (repeat 100 1))) takes a looooong time
03:29	seancorfield	instead of just 50 seconds
03:29	amalloy	seancorfield: are you sure you're actually forcing all the results?
03:29	amalloy	try (comp doall pmap)
03:30	seancorfield	yeah, i'm actually doing a (reduce + ... ) on it, sorry
03:30	seancorfield	but (reduce + (map expensive (repeat 100 1))) was very consistent at around 15 seconds
03:30	amalloy	hm. "shouldn't" be any memory left over afaict
03:30	seancorfield	when i did it with pmap, it would always take about 5 seconds the first time
03:31	amalloy	$source pmap
03:31	sexpbot	pmap is http://is.gd/mVHNdG
03:31	seancorfield	and then longer and longer on subsequent times
03:32	seancorfield	anyways, i was mostly just curious how many people were using pmap and what they were seeing
03:32	amalloy	seancorfield: i used it once, last fall, when i was working on some computationally-intensive stuff
03:32	amalloy	slowed me down when i used it naively, gave a moderate speedup when i used it sensibly
03:33	seancorfield	so maybe my problem is memory usage?
03:33	amalloy	maybe, but i can't see why the first run would be any different speed-wise
03:34	amalloy	or memory-wise
03:35	seancorfield	i'll dig some more another day...
03:35	seancorfield	i wanted to use it as an example in a presentation but i can't get it to behave reliably :(
03:37	amalloy	while nobody's looking try (def pmap (constantly the-value-you-expect))
03:37	amalloy	ought to be fast enough
03:38	seancorfield	here's my test code:
03:38	seancorfield	(defn expensive[n] (reduce + (repeat 1000000 n)))
03:38	seancorfield	(time (reduce + (map expensive (repeat 100 1))))
03:38	seancorfield	(time (reduce + (pmap expensive (repeat 100 1))))
03:39	seancorfield	and that gives expected results
03:39	seancorfield	but if you add dotimes around the reduce, the pmap slows down on subsequent evaluations
03:40	seancorfield	as written:
03:40	seancorfield	"Elapsed time: 25416.303 msecs"
03:40	seancorfield	"Elapsed time: 7165.128 msecs"
03:41	seancorfield	now change it to:
03:41	seancorfield	(defn expensive[n] (reduce + (repeat 1000000 n)))
03:41	seancorfield	(time (dotimes [_ 2] (reduce + (map expensive (repeat 100 1)))))
03:41	seancorfield	(time (dotimes [_ 2] (reduce + (pmap expensive (repeat 100 1)))))
03:42	seancorfield	and you get:
03:42	seancorfield	"Elapsed time: 49866.352 msecs"
03:42	seancorfield	"Elapsed time: 40540.13 msecs"
03:42	seancorfield	the map behavior is consistent: 2 x 25s is about 50s
03:42	seancorfield	but pmap goes from 7s to 40s... which means the second run takes 33s???
03:43	amalloy	seancorfield: or, if you're using the same repl still, both of those two are slower
03:44	seancorfield	well, yes... but really? why would pmap slow down when run multiple times?
03:44	seancorfield	each run was on a new repl... i'm running it with 4x now... just to see...
03:44	amalloy	i'd probably say ask on the mailing list. my best guess is that Thread objects are expensive?
03:45	seancorfield	lol... i will ask on the mailing list :)
03:45	seancorfield	but if thread objs are expensive, why is the single run so fast?
03:45	seancorfield	ok, 4x shows map at "Elapsed time: 97701.973 msecs"
03:45	seancorfield	which is exactly what is expected
03:46	seancorfield	still waiting for pmap run to finish :)
03:53	amalloy	$source future
03:53	sexpbot	future is http://is.gd/9xaEGV
03:54	amalloy	i wonder if the future objects somehow aren't being marked as "done"
03:57	amalloy	seancorfield: my aging 2-core machine does not thank me for pasting your code
03:58	seancorfield	lol sorry :)
03:59	markoman	i need some design tips and advices for my forms app. particularly when im making questions types for forms, im not sure how should I code it in clojure
04:02	markoman	each question type has few different views they need to produce: creation of question, preview (html text mode), search view, report view (plain text mode), etc
04:03	amalloy	seancorfield: fwiw i see similar behavior, on 1.2.0
04:04	markoman	I could have question types core for generic behavior and using components, but where should I put each qtype, separate file each of them? own directory?
04:05	markoman	should I use clos/oo with this or just pure functions, maybe macros
04:06	markoman	I need to have flexible system, so that new question types are easily to be added later
04:07	no_mind	how do I fix error in line no. 0 "Exception in thread "main" java.lang.ClassCastException: clojure.lang.LazySeq cannot be cast to java.lang.String (webserver.clj:0)
04:07	no_mind	"
04:09	amalloy	seancorfield: maybe the Thread objects just take some extra time to be GCd? if i do something else for ~5min between runs, the time goes down instead of up
04:12	Havvy	,(.split "This is a test message FOR sure!" " ")
04:12	clojurebot	#<String[] [Ljava.lang.String;@82190a>
04:13	Havvy	How can I get it to show the actual string?
04:13	Havvy	Err, array of strings...
04:14	amalloy	&(seq (.split "This is a test message FOR sure!" " "))
04:14	sexpbot	⟹ ("This" "is" "a" "test" "message" "FOR" "sure!")
04:14	Havvy	Ah. That seems a bit annoying.
04:15	markoman	if I create a qtypes directory and put each qtype there in separate file, and say I have a set of questions on form each having type declared then on different parts of the application I should be able to call qtypes/single-select/generate-search-view-mode or something like that
04:16	amalloy	Havvy: feel free to change the source code of java.lang.String.toString
04:16	amalloy	er, String[].toString
04:16	Havvy	Erm, that sounds like a scary prospect.
04:16	Havvy	Creating a wrapper function is easier.
04:16	amalloy	indeed, i would characterize it as not possible
04:19	amalloy	also, seq is already a wrapper function
04:19	amalloy	and if you want clojure-friendly structures, use clojure functions instead of String.split
04:19	Havvy	Is there a clojure function that acts as String.split?
04:19	amalloy	&(doc clojure.string/split)
04:19	sexpbot	⟹ "([s re] [s re limit]); Splits string on a regular expression. Optional argument limit is the maximum number of splits. Not lazy. Returns vector of the splits."
04:20	Havvy	Excellent.
04:20	amalloy	see also ##(doc re-seq)
04:20	sexpbot	⟹ "([re s]); Returns a lazy sequence of successive matches of pattern in string, using java.util.regex.Matcher.find(), each such match processed with re-groups."
04:25	Havvy	I feel both newbish and noobish. :(
04:28	amalloy	re-seq is pretty sweet
04:29	amalloy	if you have a reason to use regexes, anyway
04:30	markoman	im not sure if this makes any sense, but somethin glike this im thinking at the moment: (defn form-question-get [type mode & args] (call mode args (load "qtypes/{type}")))
04:31	Havvy	It is prettys sweet, and the example on cojuredocs even does what I want. :P
04:31	markoman	or actually load should be called before calling mode but anyway
04:37	markoman	or maybe I can (use 'forms.qtypes.{type}) is it bad practice to call (use) with same type over and over again? and when next type is called, it has similar function names than other types... maybe there is a name collision
04:38	seancorfield	amalloy: thanx for trying that code... the 5 min away time is very interesting
04:38	seancorfield	that suggests i just need more heap (and let java GC things in between)
04:38	amalloy	seancorfield: i think it may have been an illusion. just tried it after like 20 minutes and it took longer ;P
04:39	seancorfield	hahaha... ok... so it _is_ broken then? :)
04:39	amalloy	probably
04:39	amalloy	who knows
04:39	seancorfield	btw, where in the world are you to be online at this time?
04:39	markoman	my next try would be something like this: (defn form-question-get [type mode & args] (use 'forms.qtypes/{type}) (mode args))
04:39	amalloy	san francisco, and stupid
04:39	seancorfield	oh, you're that local to me?
04:40	amalloy	you were at the clojure meetup, right?
04:40	seancorfield	i'm in castro valley
04:40	seancorfield	yeah
04:40	seancorfield	well, not at the april 7th one
04:40	seancorfield	i was at the CI Summit at linkedin
04:40	amalloy	i was at the last two
04:40	seancorfield	but yeah i've been at some of the bay area clojure meetups
04:41	seancorfield	bummed i missed clojureconj last year... but i _will_ be at it this year come hell or high water!
04:41	amalloy	yeah, same
04:42	seancorfield	i was in england for the march one
04:42	amalloy	at the time i was just picking up clojure, seemed a little too hardcore for me to go to the conj
04:42	seancorfield	i was in albuquerque :(
04:42	seancorfield	i had a cat show in ABQ then Adobe MAX in LA
04:43	seancorfield	this year i'm doing scala days, strange loop and clojure conj
04:43	amalloy	oh, i was trying to figure out where in england albequerque is
04:43	seancorfield	:D
04:43	seancorfield	i was speaking at a conference in scotland
04:43	amalloy	that's not in england either
04:43	seancorfield	dallas, then scotland... home for a bit... then speaking in minneapolis...
04:44	seancorfield	i'll be bloody glad when my "conference season" is over!
04:44	amalloy	fortunately nobody thinks i'm interesting enough to hear me talk
04:45	seancorfield	i enjoy attending conferences more than speaking at them
04:46	Havvy	amalloy: That is not true. I would love to see a talk by you.
04:46	amalloy	Havvy: alas, i spend more time helping out in irc than doing actual things
04:47	Havvy	Alas, I know the feeling all too well.
04:48	Havvy	Perchance, do you know how to get parenthesis to colorize in a default Clojurebox setup?
04:48	amalloy	clojurebox is...what, emacs?
04:48	Havvy	23.1 of emacs, but yeah, emacs.
04:48	amalloy	$google emacs rainbow paren
04:48	sexpbot	First out of 181 results is: clojure - How do I get "rainbow parentheses" in emacs? - Stack ...
04:48	sexpbot	http://stackoverflow.com/questions/2413047/how-do-i-get-rainbow-parentheses-in-emacs
04:50	amalloy	anyway seancorfield, thanks for the reminder re time. unlike today, i have to be awake tomorrow morning
04:50	Havvy	Night amalloy, and once again, thanks for the help.
04:50	amalloy	ta-ta Havvy
04:50	seancorfield	me too... gotta get up early and do litter boxes :(
05:47	Totramon	I'm having a problem with a "Too many arguments to def" exception when 40-something iterations into a loop
05:51	Totramon	I wonder what could break after so many iterations?
05:52	Totramon	and with such an exception msg
05:52	angerman	Totramon: what does your code look like?
05:55	Totramon	well, I'm implementing a genetic algorithm so it's a lot of code
05:55	jwr7	Is there a way to tell Clojure that I'm trying to aget something from a Java array of Strings (built using into-array? (and avoid reflection)
05:55	angerman	Totramon: what's the code arround the error?
05:56	Totramon	but well the outer loop is a loop - do - print - recur
05:56	jwr7	Basically, clojure complains about (aget arr i)
05:56	Totramon	I do not know what triggers it - the exception comes from repl
05:57	Totramon	the most recent item on stack trace is clojure.lang.Compiler$DefExpr$Parser.parse (Compiler.java:415)
05:57	angerman	Totramon: don't look at the most recent, scan the stacktrace for parts that contain your file.
05:58	Totramon	there's nothing related to my code in it
05:58	Totramon	hm, could there be a time limit to execution?
05:58	angerman	without you setting it? not that I know of.
06:01	Totramon	this is the output from the exception: http://pastie.org/1778250
06:03	angerman	that's all?
06:03	angerman	wow.
06:03	Totramon	yes
06:03	Totramon	I'm using eclipse and counterclockwise btw if that's of any relevance
06:03	angerman	then this must be an issue with a def definition.
06:04	angerman	at some point you give (def ) more then 2 arguments.
06:04	angerman	maybe somewhere there is an (apply def )? or some other function composition.
06:05	angerman	Not that I'd understand why one would do that but, it could be a possibility.
06:05	Totramon	I don't think I use an explicit def anywhere
06:05	angerman	well, without code and how you invoke it, I'm lost here.
06:06	Totramon	ok. this really starts to look like a timelimit issue, because it fails exactly after 60 seconds every time
06:06	Totramon	let's see...
06:06	angerman	I really don't think that the base repl inferes any timeout. Maybe it's counterclockwise or eclipse.
06:08	Totramon	ok I need to see if I can find such a setting somewhere
06:09	angerman	(or run it from command line ...)
06:09	angerman	or try something like (Thread/sleep 80*1000)
06:09	angerman	I still doubt it though.
06:13	Totramon	sleeping for 80 seconds didn't cause an exception
06:13	Totramon	although, it didn't return a nil, either
06:39	Totramon	oh, but of course... the stack trace was for a random exception
06:40	Totramon	when the execution failed it didn't except at all
06:41	Totramon	so actually the only error I get is "Expression failed <however I called it>"
06:42	Totramon	found a relevant post now, too. thanks for help anyway
06:43	Totramon	ccw does have an evaluation timeout of 1 minute
06:44	Totramon	think I need to switch away from the RC version for now
07:21	cods	Is there a shortcut for (map (fn [o] (.myMethod o)) seq) ? I tried (map .myMethod seq) which is rejected.
07:22	cods	well, I could do (map #(.myMethod %) seq)
07:22	cods	which is short enough for me
08:22	fliebel	Where does the ants demo by Rich live? I believe someone updated it a bit?
08:24	fliebel	Ah, maybe this one?
08:24	fliebel	https://github.com/krukow/ants-demo
10:14	mec	how might i write a macro to turn (f a b) into (f 'a 'b)
10:16	Vinzent	something like `(quote ~arg) ?
10:17	TimMc	mec: (some-macro f a b) -> (f 'a 'b) is what you want?
10:18	mec	yes
10:18	TimMc	I'm not sure why you wouldn't just write (apply f '(a b))
10:18	mec	hmm indeed
10:19	mec	$findfn '[x 5] 'x 5
10:19	sexpbot	[clojure.core/let clojure.core/loop clojure.core/when-let clojure.core/if-let]
10:19	mec	basically I dont want to have to do that
10:22	TimMc	but... (defmacro foo [f-expr & arg-syms] `(apply ~f-expr '(~@arg-syms)))
10:33	mec	well so much for that, doing it kills the ability to process regular functions
10:40	mec	Is there a better way to do (juxt last butlast) that wont run the seq twice
10:45	TimMc	mec: Are you talking about lazy seqs, or about just needing to potentially walk through the whole thing?
10:46	mec	just walking it twice
10:46	TimMc	k
10:46	mec	right now i've just got #((juxt peek pop) (vec %))
10:46	TimMc	nod
11:12	mec	is there a version of keep that only keeps truthy values?
11:14	fliebel	mec: Isn't that what keep does?
11:14	mec	keeps false values also
11:14	TimMc	mec: filter identity :-P
11:15	TimMc	just filter might be what you want
11:16	TimMc	I guess the question is whether you want to keep the inputs or the outputs of your predicate.
11:16	mec	i guess i can just adjust the predicate to not return false
11:22	TimMc	$findfn identity '(nil false 1 true) '(1 true)
11:22	sexpbot	[clojure.core/filter]
11:23	mec	,(str (doall (range 10)))
11:23	clojurebot	"clojure.lang.LazySeq@9ebadac6"
11:27	fliebel	&(str (seq (range 10)))
11:27	sexpbot	⟹ "(0 1 2 3 4 5 6 7 8 9)"
11:49	fliebel	I need to merge multiple maps into one, but not just accumulate keys and the last wins, but more like git-style.
11:52	fliebel	So say I have the original map, one map that has :x removed and one that has :y incremented. Now I want the result to be a map without :x and with the incremented :y.
11:52	TimMc	fliebel: The value are all numbers that are manipulated with addition?
11:53	fliebel	TimMc: No.
11:54	TimMc	How will you know that y was incremented as opposed to scaled?
11:54	fliebel	TimMc: I just care about changed, if both maps had :y changed, last-wins is okay.
11:54	fliebel	-ish
11:55	fliebel	I can think of something with clojure.set for changes, but I struggle with the deletions.
11:57	TimMc	(difference (set (keys a)) (set (keys b)))
12:00	fliebel	well… okay… hmmm… so that is one difference on the values for the changes and a revered one on the keys for the removals. And then stitch it back together.
12:00	fliebel	*reversed
12:06	TimMc	fliebel: select-keys is your friend here
12:07	fliebel	TimMc: dissoc rather, I'd say. What comes out of the first diff can be conj'd into the original, and what comes of the second diff can be dissoc'd from that.
12:07	TimMc	Hmm, that works too.
12:17	fliebel	weee! user=> (octopus {:a 1 :b 2 :c 3 :d 4} {:a 2 :b 2 :d 4} {:a 1 :b 2 :c 3 :d 3}) {:a 2, :b 2, :d 3}
12:18	fliebel	TimMc: ^
12:19	shachaf	fliebel: Instead of finding it mildly annoying, find it deeply infuriating. Then you'll care enough to fix it.
12:20	shachaf	That's what I do, anyway.
12:21	TimMc	fliebel: nice
12:37	xkb	hi
12:37	xkb	I'm trying to fix this macro: https://gist.github.com/912494
12:37	xkb	where func should be the literal name of a function
12:38	xkb	I tried slicing and slice-unquote, but I think I'm missing something as I keep getting error messages
12:38	xkb	even on expand, esp. when I give something like Library/addArtist (a Java static method) as input parameter
12:38	xkb	any idea what I'm doing wrong?
12:39	Chousuke	xkb: you want (~func ~@args), most likely
12:40	xkb	so without apply?
12:40	Chousuke	(apply func ~args) expands to something like (apply func (arg1 arg2 arg3))
12:40	xkb	and that's what I want
12:40	Chousuke	no you don't :)
12:40	xkb	apply func to the arguments
12:40	Chousuke	you don't want to call the first arg as a function
12:40	Chousuke	with my form, you'll get (func arg1 arg2 arg3)
12:41	xkb	that's equal to (apply func (list arg1 arg2 arg3)) right?
12:41	__name__	Since when does Clojure have ~?
12:41	Chousuke	yes?
12:41	Chousuke	__name__: ~ is unquote
12:41	__name__	Ah.
12:43	Chousuke	xkb: note that (apply func (list arg1 arg2 arg3)) is not the same as (apply func (arg1 arg2 arg3)) :)
12:43	xkb	args is a list, due to & right?
12:43	xkb	so args actually is (list ....)? Or is that a wrong assumption?
12:44	Chousuke	hm
12:45	xkb	I think I'm missing something, can't really point out what though
12:45	Chousuke	,((fn [& args] `[args ~args ~@args]) 'some 'args 'here)
12:45	clojurebot	[sandbox/args (some args here) some args here]
12:46	Chousuke	that's what gets used as the code
12:47	xkb	so I want the second, ~args I presume
12:47	xkb	as is in my code now
12:47	Chousuke	no
12:47	xkb	or without apply, the third
12:48	Chousuke	because then your code will end up being (apply func (arg1 arg2 ...))
12:48	Chousuke	and (arg1 arg2 ...) is a function call form
12:48	xkb	ahh yes
12:48	xkb	hmm 2 bad :) I had hoped to abuse the () form to append one extra argument
12:49	Chousuke	you can also do (apply func ~(cons `list args))
12:49	Chousuke	or (apply func ~(vec args))
12:49	xkb	ah yes
12:50	xkb	just delay the splice
12:52	xkb	anyway, this leads to the second problem.. if I try to expand the now changed macro, I get the error that the var func is not there..
12:52	xkb	called like this: (macroexpand-1 (with-error-handling (fn [a b] (Library/addArtist a b)) "OK" "FAIL" "Murk" (get-session)))
12:52	xkb	ah.. that anonymous
12:53	xkb	that's even
12:55	fliebel	Is there any way to kill a loop in lein without killing lein?
12:55	Chousuke	xkb: you need to unquote the func too.
12:55	xkb	Chousuke: thanks for the help!
13:02	xkb	oh, one more question. I expected a macroexpand on the with-error-handling macro to show the expanded macro, including the let. Instead it just shows the result of the computation, i.e. "OK". Why is that?
13:12	Chousuke	xkb: did you remember to quote the form that you macroexpand?
13:12	Chousuke	,(macroexpand-1 '(fn [] test))
13:12	clojurebot	(fn* ([] test))
13:14	xkb	ah I forgot the quote
13:14	xkb	thanks again
13:31	mec	fliebel: what did you end up using to merge your maps?
13:54	markoman	how can I do this kind of operation on clojure: (use 'lib.sublib."file")
13:55	markoman	the last part of the use is changing so practically if I have a library path on string format, how can I "use" it?
13:57	markoman	i could perhaps provide last part in format (use 'lib.sublib.:my-file) too
14:06	fliebel	markoman: Maybe (use ['lib (symbol "sublib")])
14:06	fliebel	oh, wait, load-ile probably.
14:06	fliebel	*load-file
14:07	markoman	there might be several loads for same file, does that matter?
14:08	fliebel	markoman: Multiple invocations of load-file will not return the previous result.
14:09	fliebel	Maybe you could memoize it :)
14:10	markoman	ha, ive seen that word, memoize but dare not to find out, what it means
14:10	fliebel	markoman: It is really simple, it just stores arguments in a map, and when you run a function with the same argument, it looks up the return in that map rather than running the function again.
14:11	markoman	hmh, so far sounds like it could fit in this case
14:12	fliebel	markoman: Note that load-file doe not refer the loaded code, so it is not like use.
14:12	markoman	I try to design my library so, that naming convention on sublib files refer to symbols, so i dont need to create extra maps on app
14:13	markoman	see, I have this kind of situation: (defn form-question-type [type callee & args] (use '(str "magicforms.qtypes." type)) (callee args))
14:14	fliebel	markoman: w-wait, what am I conspiring in now? That sound quite bad, using use in a fn.
14:14	markoman	yes!
14:15	markoman	im experimenting it on repl and so far no idea, what I should do with it
14:15	fliebel	So you want to require stuff as you need it?
14:15	markoman	exactly, and I may need it zero, one or n times
14:16	fliebel	how much of these are there? Is it worth the trouble lazy-loading them?
14:16	fliebel	You could also look into delay.
14:17	fliebel	(def t (delay (require the.type))) @t @t will require it once.
14:18	markoman	im not sure about worth, but qtypes, its increasing library and files. all files has same functions like: create, list, show, etc
14:18	fliebel	ah, as long as you use require instead of use, that is not a problem/
14:19	fliebel	then you write qtype/create
14:20	fliebel	You can even alias these: (require '[blah.qtypes [foo :as f]]) (f/create)
14:51	markoman	fliebel: my connection broke, so did conversation in the middle...
14:54	raek	markoman: speaking of lazy code loading: http://groups.google.com/group/clojure-dev/browse_thread/thread/025821cbbfa47226#
15:03	markoman	raek: how does that affect to use, require?
15:04	raek	I merely know that this exists, nothing more... :)
15:05	raek	it struck me as a potential solution to "So you want to require stuff as you need it?"
15:07	raek	markoman: so, why do you need to dynamically load code?
15:07	markoman	hmh... you are right, im not sure how i could use it here at the moment, but I can see possibility. only thing is, that i dont want to do duplicate work for mapping things
15:07	markoman	let me try to explain that
15:08	raek	...or why is does not a :require in the ns do the trick in your case?
15:08	markoman	(defn form-question-type [type callee & args] (require '(str "magicforms.qtypes." type)) (callee args))
15:09	markoman	it probably does, i was using use as a first sketch, but guessed it may cause name pollution or other problems
15:10	markoman	i dont know exact difference between use and require. but i have a library or question types I want to load "dynamically". 0, 1 or n times depending how many questions are that type
15:10	markoman	or = of
15:11	raek	I think there are simpler ways of representing the question types than namespaces
15:12	choffstein	Hey all. I have a quick question. I keep getting an arity error, but I can't figure out why.
15:12	choffstein	I've used let to define a function (e.g. (let [f (fn [a b c] ...)])). When I try to pass it three arguments, though, I am told I am only passing it two ... which is horrendously frustrating.
15:13	raek	markoman: this cannot work, since before a function is compiled, all vars it uses (e.g. fns in other namespaces) must be loaded
15:13	markoman	i was thinking clos / oo approach too, but here the main criteria is, that librarry is evolving and growing, and each question type has functions lie: create-get, list-get, show-get, validate-get, search-get and so on
15:13	choffstein	Any ideas why this may be happening?
15:13	raek	well, technincally, the vars need to exist
15:14	raek	choffstein: I don't see anything strange in that snippet there
15:14	trptcolin	choffstein: what raek said. what's the caller look like?
15:15	raek	markoman: is there any reason you can't store everything in ordinary clojure data structures?
15:15	markoman	raek, but if there are no vars, just function on each qtype file?
15:15	raek	vars in namespaces is what "names" functions...
15:16	raek	when you have (defn foo [] (bar)), bar is a reference to the bar var, not the function it holds
15:16	choffstein	trptcolin: like (f 1 2 3)
15:16	markoman	raek, probably not :) this is just the way, I have made it on other language, but they werent compile languages, python and php namely so I could just load what I needed
15:16	choffstein	trptcolin: I'll gist it
15:16	raek	yeah, in python, a module is basically just an object with attribues
15:16	raek	in clojure, that is not exactly the case
15:17	raek	so clojure is more "compily" in this aspect...
15:17	trptcolin	choffstein: cool
15:18	markoman	i see. but i still would like to have all types easy and separate, so I can add, modify them later if needed. think of adding new type by defining mandatory functions
15:18	raek	I would recomment having a global var holding some data structure that contains that stuff
15:19	choffstein	trptcolin: https://gist.github.com/912628
15:19	choffstein	trptcolin: first-date, (get (:data file-data) first-date), and initial-index-value all evaluate correctly.
15:19	trptcolin	:) haha, "..." indeed
15:19	markoman	im afraid it can get complicated... well maybe not a problem. but I can have dozens of question types, simple and custom qtypes. and each of them needs to have same functionality that the form building function can call
15:20	raek	you could have a map like {:foo {:create (fn ...), :list (fn ...), :show (fn ...), :validate (fn ...), :search (fn ...)}, :bar ...}
15:20	choffstein	And the error is: Wrong number of args (2) passed to: core$construct-index-by-pct$shares-on-date
15:20	devn	clojure project! https://github.com/codahale/metrics
15:20	devn	scala -> clojure
15:20	choffstein	trptcolin: actually, hold on. the whole file is up on github. let me find it.
15:20	raek	remember that it is possible to store functions in data structures too :)
15:21	choffstein	trptcolin: https://github.com/newfoundresearch/construct-index/blob/master/src/construct_index/core.clj -- in construct-index-by-pct
15:21	raek	markoman: I don't know much about the design problems you're facing, but I can tell you this: representing domain data as vars in a namespace will just make it even more complicated
15:21	choffstein	trptcolin: don't be too harsh on the code -- it is my first run through on it. just getting it to work before refactoring
15:21	markoman	yeah, I saw that once on some code :) I guess that could work. and you think putting it on separate files is not good? say other developers want to add new type, they could just put new file on system and thats it?
15:22	trptcolin	i won't be :) i'm just thinking it'd be easier to debug with functions split out to remove dependencies
15:23	choffstein	trptcolin: I was trying to keep them in the let because they relied on the values above -- and the inner functions are different within construct-index-by-pct and construct-index-by-shares
15:23	raek	markoman: perhaps you can have an namespace that acts as an api with functions for adding qusetion types?
15:23	raek	markoman: I have a feeling that what you do is similar to how 'derive' works in clojure
15:24	raek	it allows libraries to add stuff to a global hierarchy
15:24	markoman	probably, i need to check google
15:26	raek	it could be as easy as having (def types {}) (defn register-type [name stuff] (alter-var-root #'types assoc name stuff))
15:27	raek	or if things change at runtime: (def types (atom {})) (defn register-type [name stuff] (swap! types assoc name stuff))
15:27	trptcolin	choffstein: i wonder about this line: "(reduce #(+ %1 (Double/parseDouble %1)) 0 data-row)"
15:27	trptcolin	,(reduce #(+ %1 %1) 0 [1 2 3 4 5])
15:27	clojurebot	java.lang.IllegalArgumentException: Wrong number of args (2) passed to: sandbox$eval5396$fn
15:28	trptcolin	you probably want a %2 in there somewhere
15:28	choffstein	ahhhh, yes
15:29	choffstein	you, sir, are a genius!
15:29	trptcolin	it'd be nice for that error message to give some clue that the fn in question is anonymous under the fn it gives...
15:30	trptcolin	but yeah, generally if you can find a way to break that up it'll be easier to verify all your behavior is what you intend :)
15:30	raek	markoman: if you have something like that, other namespaces can add types. splitting code into managable chunks is always a good idea...
15:31	markoman	i dont think I let types change at runtime, when new types comes in, I need to deploy anyway. its just for code management
15:32	trptcolin	devn: that looks pretty tasty
15:32	markoman	I can think now for using global map as you suggested, maybe combines to that each namespace adds new section on map, or the other register type way...
15:36	markoman	oraek: but you still mean I need to register all question types on same types map?
15:37	raek	markoman: well, you could have multiple maps. but the point is that the number of vars holding maps should not vary with the number of namespaces that needs to add information
15:38	raek	maybe it helps to think of vars in namespaces to be static
15:40	markoman	ok, well now, because I need to add all qtypes on map and they all are in qtypes directory, is there a way to read directory and simply add all that is found by their file / namespace name?
15:41	raek	also, will the namespaces only contian data (and no code)?
15:41	raek	if so, it might simply be better to load data from some files
15:41	markoman	so I could escape from duplicate writing because all qtype filenames are already qtypes
15:42	markoman	well because data structure can hold functions, it would be only data :)
15:44	raek	its probably possible to scan a directory on the CLASSPATH for .clj files and load them
15:44	raek	but as a start, it is probably easier to just list them in the :require form in some namespace
15:45	markoman	ok and sorry, I have no good example to show, because its all immature for now, maybe I try with these tips and get back with questions
15:46	raek	I think it's easiest to start with functions that use the data first, and build a question module system on top of that later
15:57	markoman	raek: btw why you use alter-var-root and not just (types assoc name stuff) ?
15:59	mreynolds	newb question : I'm trying to run a multi-module program I've written. I can get the main method up, but I'm confused about why sometimes I get CNFE for some classes, but not others. Am I supposed to be using gen-class?
16:00	raek	markoman: 'types' contains a map, and calling it as a function won't do what you think
16:01	raek	(m key) (m key default) are the same as (get m key) and (get m key default)
16:01	mreynolds	A better way of saying this is, what "I need to use methods from other modules" keyword am I supposed to use when I'm writing an all-clojure program? I've been using a mix of "use" (for utility methods) and require for modules
16:02	trptcolin	mreynolds: use and require are generally for vars - if you're using defrecord/deftype you'll need import as well
16:02	raek	mreynolds: are we talking about methods and classes (java land) or functions and namespaces (clojure land)?
16:03	mreynolds	trptcolin: Thanks, that's what I just realized wasn't working. I need import because it's creating real Java classes?
16:03	trptcolin	yep
16:03	mreynolds	raek: functions, sorry. Java trained brain. This is all clojure code (which sometimes uses java), but the problem so far is all in my clojure only code.
16:04	raek	mreynolds: you should not get CNFE for clojure-only stuff
16:05	raek	import is only for shortening the name of java classes (and is not used for namespaces)
16:05	mreynolds	raek: Hmm
16:05	raek	so, I assume you files looks something like this:
16:06	raek	in file src/a/foo.clj: (ns a.foo) (defn hello ...)
16:06	mreynolds	So, here's the setup. I have a defrecord (ns com.example.x.y.z) (defrecord Location [a b c]). Then I have (ns com.example.d.e.f (:import com.examples.x.y.z Location))
16:07	raek	in file src/a/bar.clj: (ns a.bar (:use [a.foo :only [hello]])) (def blah [] (hello))
16:07	mreynolds	I'm double-checking for typos, but the import seems to be not working
16:07	raek	ah, I see
16:07	trptcolin	(:import [com.examples.x.y.z Location])
16:07	trptcolin	(needs the vector)
16:07	raek	you need to both require the namespace that defines the record and then import the class
16:07	mreynolds	trptcolin: That's it. Thanks. I need to create a cheat sheet for that.
16:07	mreynolds	import doesn't do both, eh?
16:07	mreynolds	Weird
16:08	mreynolds	Or, weird to my yet-to-be-trained-brain
16:08	raek	sorry for misleading you. you can indeed get CNFE this way...
16:08	raek	this is a known problem
16:08	mreynolds	raek: no worries
16:08	trptcolin	yeah, records are a bit fussy wrt nses...
16:08	mreynolds	raek: I've dealt with Java for so long, this actually seems happy and warm and soft
16:09	mreynolds	I think I get the underlying issue, mainly that records are official objects, get created as such, and this need to be imported
16:09	mreynolds	Rather than "used"
16:09	raek	I common workaround for this is to let the user use a constructor function, instead of the record class constructor
16:10	mreynolds	raek: Yeah, I read that in the Joy of Clojure (I think), and plan to switch to that now
16:10	raek	http://dev.clojure.org/display/design/defrecord+improvements
16:11	mreynolds	raek: Thanks!
16:12	raek	(import only affects how symbols are resolved the namespace, and doesn't do any loading)
16:13	raek	*in the
16:14	mreynolds	Right, basically via java lookup, directly in the NS, or via a lookup? This is one the murkier parts of clojure that my brain has trouble with, but I think I have it down enough to get a working app up
16:15	mreynolds	import :: java, use :: directly in ns, require :: referenced via keyword
16:15	mreynolds	?
16:18	raek	(import 'javax.swing.JFrame) only causes JFrame symbols to resolve into javax.swing.JFrame in the current namespace
16:18	raek	require and use on the namespace foo.bar causes the file foo/bar.clj to be evaluated if it hasn't been already
16:19	mreynolds	raek: Tangential question - Why use 'javax.swing.JFrame vs (javax.swing JFrame)?
16:19	mreynolds	ah, good to know about evaluation
16:19	mreynolds	I have read this stuff, but it's not sticking immediately, sorry for the newb questions
16:19	trptcolin	those are equivalent, but you might want (javax.swing JFrame Icon Action)
16:19	raek	'(javax.swing JFrame) is easy to change into '(javax.swing JFrame JLabel) :)
16:20	trptcolin	word
16:20	trptcolin	mreynolds: you probably just covered everything, but i have a blog that goes into some detail about these: http://blog.8thlight.com/articles/2010/12/6/clojure-libs-and-namespaces-require-use-import-and-ns
16:20	raek	use, but not require, will cause all the vars in that namespace to be available without a complete namespace prefix
16:20	mreynolds	trptcolin: I'll go read that
16:23	mreynolds	Oh, one other rub. I'm doing the "Load a script" incantation from ( http://clojure.org/repl_and_main ), is there a way to have main start a repl after executing my script? I tried "-r" but that just starts a repl, without loading my script?
16:24	mreynolds	I thought about just using a script with a hardcoded -e that loads my program, but haven't figured out if that would work yet
16:25	choffstein	Can I check if a Java Date is in a collection using contains?
16:25	choffstein	It doesn't seem to be working for me and I can't figure out why
16:25	trptcolin	what kind of collection? :)
16:25	raek	clojure is not really made for scripting, so something like 1) start a repl 2) require start namespace 3) invoke (start.namespace/-main) is probably the easiest
16:26	choffstein	list
16:26	raek	choffstein: 'contains?' should be read 'has-key?'
16:26	trptcolin	contains? may not work as you expect for things other than sets & maps
16:26	clojurebot	Titim gan éirí ort.
16:26	choffstein	ahhhh
16:26	choffstein	well, that explains it then!
16:27	choffstein	is there a way to check if a list contains an element?
16:27	raek	to do a linear seatch for the element, use (some #{elemenent} coll)
16:27	raek	but if you search for elements in the collection often, you might want to consider to use a set as the datastructure
16:28	raek	since those are specialized in checking membership
16:28	choffstein	raek: yeah, a set would be much better
16:48	markoman	so i got this far: (:search (qtypes :single-select) "args1") it returns the function, but how do I actually execute it?
16:48	brehaut	((:foo {:foo inc}) 1)
16:48	brehaut	,((:foo {:foo inc}) 1)
16:48	clojurebot	2
16:49	markoman	cool, thanks
17:17	markoman	(defn element ([name] (element name nil)) ([name value] (element name value nil)) ([name value id] (element name value id nil)) ([name value id options] ,,, ))
17:17	markoman	is there some smarter way to do this, because I see its going to repeat again and again for different elements
17:28	seancorfield	markoman: maybe use named arguments with defaults instead?
17:29	Derander	is there a way to pass -Xms and -Xmx args through lein swank to increase heap size?
17:29	markoman	this is the way i though it is done in clojure :)
17:32	seancorfield	(defn element [name & { :keys [value id options] :or {value nil id nil options nil}}] (println name value id options))
17:32	seancorfield	(element "n" :value "v" :id "i" :options "o")
17:32	seancorfield	(element "n")
17:32	seancorfield	(element "n" :id "i")
17:33	raek	markoman: it is the only way to do it if you want it to only allow the arities you specify
17:33	seancorfield	pity you can't have a [name value id options] :or [nil nil nil nil] sort of destructuring...
17:34	raek	someone should make a macro for this...
17:34	markoman	i think I once saw related macro...
17:37	raek	(defn-default element [name ? value nil, id nil, options nil] ..) -> (defn element ([name] (element name nil nil nil)) ([name value] (element name value nil nil)) ...)
17:51	markoman	clojure.contrib.def/defnk could work?
17:53	seancorfield	defnk would provide syntactic sugar vs what i was suggesting, yes
17:58	markoman	alright, its time to sleep. thanks sean and raek for your insights
17:58	seancorfield	here's a version with optional positional args:
17:58	seancorfield	(defn element [name & xs] (let [args (args-to-map [:value :id :options] xs [nil nil nil])] (println name (:value args) (:id args) (:options args))))
17:58	seancorfield	(defn args-to-map [ names values defaults ] (apply hash-map (apply concat (map list names (make-default values defaults)))))
17:59	seancorfield	(defn make-default [values defaults] (if values (cons (first values) (make-default (next values) (next defaults))) defaults))
17:59	seancorfield	i'm sure there's much cleaner versions of those two helper functions
17:59	markoman	so its much talked about syntactic sugar, but what is syntactic salt then?
17:59	seancorfield	but a little macro magic could make it much cleaner
18:02	markoman	i see, i need to copy that for tomorrow and see how things work
18:46	mec	does destructuring change the collection type?
18:47	brehaut	mec: if you use a vector to destructure a vector and use a remainder form, then you get the remainder as a seq if thats what you mean
18:47	brehaut	mec: otherwise you get the elements as they are in the collection
18:48	mec	ah, so i shouldnt destructure a queue
18:48	brehaut	mec and the collection itself doesnt change due to the destructuring
18:48	brehaut	mec: it depends/
18:49	brehaut	mec: in particular it depends on what sort of queue you are using
18:49	mec	PersistentQueue
18:49	brehaut	mec then i cant see it being a problem
18:50	brehaut	mec: unless you want to just treat the remainder as a queue
18:50	mec	if I do (let [[x & rqueue] queue] ...) if it changes rqueue from a PersistentQueue then i wont be able to keep using it
18:50	brehaut	rqueue is never a persistentqueue
18:51	brehaut	,(destructure '[[x & r] [1 2 3]])
18:51	clojurebot	[vec__5404 [1 2 3] x (clojure.core/nth vec__5404 0 nil) r (clojure.core/nthnext vec__5404 1)]
18:51	brehaut	mec: you can see that r is bound to the result of nthnext
18:52	mec	ah ok
19:24	mec	how might I conj 2 items onto a collection so that if either is nil that one wont be added
19:25	mec	(into coll (filter identity [x y])) i guess but i just hate filter identity for some reason
19:32	mreynolds	I have a "plugin" framework I'm trying to build, where I have an agent keeping track of the functions that I want to "plugin". I have an event and I want to have all the plugin functions run, passing in this event. I'm missing something obvious because -> isn't doing what I expect (-> event (registered-plugins)) where (registered-plugins [] @agent-name)
19:37	mec	registered-plugins is a vector of agents?
19:37	mreynolds	mec: Set, actually
19:37	mreynolds	mec: Er, it's a set, held by an agent
19:38	mreynolds	mec: Er, wow, sorry. Vector held by an agent.
19:38	mec	(-> event (registered-plugins)) is just (registered-plugins event) but if registered-plugins is an agent you would need (@registered-plugins event)
19:39	mreynolds	I'm trying map, and everything seems to be running... it's just not executing those functions. I have a sneaking suspicion it's being lazy
19:39	mreynolds	mec: oh, neat
19:39	mreynolds	mec: Lemme try that
19:41	mreynolds	mec: I must be doing something dumb because that seems to be treating event as an index into the vector
19:41	mreynolds	mec: the contents of the vector are functions, if that helps
19:42	mec	oh and you want to run each function with event as arg?
19:42	mreynolds	yeah, sorry
19:42	mreynolds	mec: Brain is getting a bit worn
19:43	mec	((apply juxt @registered-plugins) event)
19:43	mreynolds	mec: It feels like a pretty simple problem, but I have too many levels of indirection I'm not familiar with yet.
19:43	mreynolds	I'll try that
19:45	brehaut	mec: perhap you would prefer (remove nil? col) ?
19:47	brehaut	mreynolds: (map #(%1 event) @plugins-agent) ?
19:47	mec	brehaut: I thought about that one, but that juxt just looks beautiful
19:49	brehaut	mec: im not sold on it for this usage
19:49	mreynolds	mec: That worked
19:49	mec	he mentioned map being lazy so it saves an extra (doall)
19:49	mreynolds	brehaut: Almost worked, but didn't print... I think it's a lazy issue between the two styles?
19:50	mec	mreynolds: for the map you gotta wrap it in a (doall (map ..)) for side effects
19:50	mreynolds	mec: Yup
19:50	mreynolds	thanks
19:50	mreynolds	Is there an easy way to tell that a chain is lazy and won't be called?
19:50	mreynolds	I mean, normally, that's awesome
19:51	mreynolds	For debugging purposes, with println, it's not so awesome
19:51	brehaut	mreynolds: know what your data is?
19:52	mreynolds	brehaut: Yes, events coming in from a client. Normally, each function would be called an will act upon that event, possibly returning other events to be sent back to the client. Not in this case, though.
19:52	mreynolds	Did I answer your question?
19:52	brehaut	mreynolds: nope; i mean that you need to know what your data is to know when it needs to be realized etc
19:53	mreynolds	brehaut: Sorry, not sure what "realized" means in that sense
19:53	brehaut	mreynolds: a lazy computation is only evaluated when it is realized
19:53	brehaut	realization is the process of taking that thunk and replacing it with the computed result
19:53	mec	pretty much if you use any of the core collection functions, its going to be lazy
19:53	mreynolds	brehaut: Gotcha. I think I need a way to force that for debugging purposes and I'm not sure how to do that yet.
19:54	brehaut	mec not true, only the sequence functions
19:54	brehaut	mreynolds: dorun is the answer
19:54	brehaut	mreynolds: you shouldnt be putting side effecting code into a sequence anyway
19:56	brehaut	(apply the same caveats you would to any other blanket statement to that one too)
19:56	mreynolds	brehaut: Right, I'm pretty sure I'm not thinking about this correctly yet. I have a stream of client data and I want to segregate the areas of concern and allow different modules to respond to different client requests
19:56	mreynolds	I figured building a "hub" to distribute the events to incoming modules would allow them to process the event and respond, if needed. I like that it's lazy in that case.
19:56	brehaut	mreynolds: first question then: do you care about the result of the pluggin?
19:57	mreynolds	brehaut: At this point, I don't
19:57	mreynolds	brehaut: I'm having a hard time thinking of a case where I would
19:57	brehaut	then go with no until you discover a case
19:57	mec	(doseq [f @registered-plugins] (f event))
19:57	brehaut	i would suggest using a doseq
19:57	brehaut	just like that :)
19:57	mreynolds	alright, I'lll try that :)
19:57	mec	lol
19:58	brehaut	simply because its explicit that it side effecting
19:58	mreynolds	I was avoiding it because of the "side-effects" in the docs, but that's actually exactly what I want
19:58	mreynolds	heh
19:58	mreynolds	Thanks for helping me think about that differently, guys
19:58	mreynolds	I'll go re-work a bit
19:58	brehaut	no worries
19:58	brehaut	mreynolds: side effects are fine if the program is clear about their scope and effect
19:59	mreynolds	brehaut: Yeah, that's the part I need to figure out next. I'm trying to figure out my audience so I can try and determine how much I should/shouldn't manage for them from a data and session standpoint
19:59	brehaut	mreynolds: im curious about why you have a non-pure plugin system though; what are youy building?
19:59	mreynolds	brehaut: It's a toy minecraft server, mostly so I can learn clojure more fully
20:00	brehaut	mreynolds: what are the plugins responsible for?
20:00	mreynolds	brehaut: At work, I'll be using clojure and ring to build simple REST servers so others can use them as prototypes.
20:01	brehaut	mreynolds: that should be really straight forward (ring + rest)
20:01	mreynolds	brehaut: Plugins are responsible for various tasks like : returning portions of the world when clients enter an area, managing inventory, * etc
20:01	mreynolds	brehaut: Yeah, actually way easier than this problem I have at home
20:01	brehaut	yes
20:01	brehaut	if you are doing simple json stuff its almost just falls out by itself
20:02	mreynolds	brehaut: Yeah, I will be. But I also know, eventually, I'll have to show some java interop stuff with existing badly written code, so I figured I'd stretch myself a bit and try building something larger
20:02	mreynolds	brehaut: I'm, effectively, leading several teams out of J2EE/RMI driven architecture and into something else. They'll all be using Java due to comfort with the language.
20:03	mreynolds	brehaut: Part of the reason for the plugin bit is I may try and build them a sandbox framework to deploy java code into and it would probably look similar
20:03	mreynolds	brehaut: Yeah, the existing mess is ... messy
20:03	brehaut	mreynolds: why did you chooses an agent for your plugins ?
20:03	brehaut	rather than say an atom
20:04	mreynolds	brehaut: No particular reason. I liked the async portion of agents for management of the plugins.
20:05	mreynolds	brehaut: I'm still learning which ones are best. My goal is to not allow the plugins to interrupt each in a big way, when possible.
20:05	brehaut	they one interrupt each other in either case
20:05	mreynolds	Eventually I plan to externalize the events to allow for choosing between in-process and out-of-process messsaging
20:06	brehaut	err they wont
20:06	mreynolds	brehaut: It's more about behaving really poorly (blowing the stack, heap, etc). The examples I have are simple now, but have similar constraints
20:06	mreynolds	brehaut: For the home server, the world can be mismanaged and eat a ton of memory, etc
20:07	mreynolds	brehaut: But you're right, from a processing standpoint, it won't matter
20:07	mreynolds	My primary concern, at work, will be programmers making bad engineering decisions and needing to contain those
20:09	brehaut	mreynolds: i prefer education to api constraints to solve that problem ;)
20:10	mreynolds	brehaut: That's step 2. First step is proving that they're making bad decisions without allowing them to sink the app :)
20:10	mreynolds	I'm new and I don't have a ton of buy-in for the style I'm proposing
20:11	mreynolds	I could override and be a dick about it, but I'm trying to give people a chance to try things out under less pressure, but remove the immediate risk they have
20:11	brehaut	mreynolds: in my opinion you dont want to straightjacket them
20:11	brehaut	let them make their own mistakes and learn from it
20:11	mreynolds	brehaut: In the long run, sure. In the short term, the company doesn't have the ability to absorb too many big mistakes, I think :/
20:12	mreynolds	brehaut: They are good people, mostly smart, but have been doing the same thing for 10 years and haven't upgraded skills in that timeframe
20:13	mreynolds	brehaut: There's a pretty large set of basic skills that they haven't picked up over the years. Even reading JCIP is a good start.
20:13	mreynolds	Anyway, not to rant too much about work :) I appreciate the help.
20:15	crowbar	Is there a special command for starting cake? If I initiate it in teh project root it just says jvm is taking a long time
20:16	znutar_	is using java IO classes the idiomatic way to read things from stdin?
20:16	brehaut	znutar_: yes; clojure.java.io provides utilities to do so
20:17	brehaut	znutar_: see also http://clojuredocs.org/quickref/Clojure%20Core
20:18	mec	znutar_: on the off chance that you're using emacs, reading from slime is buggy
20:25	crowbar	Is it possible to install clojureql with lein? I'm running into issues where i'm missing an artifact. org.apache.maven:super-pom.jar?
20:26	brehaut	crowbar: i have in the past
20:27	brehaut	crowbar: http://clojars.org/clojureql
20:27	crowbar	I tried that. Looks like I might have a different problem though.
20:28	brehaut	running the latest lein?
20:29	crowbar	Leiningen 1.5.0 on Java 1.6.0_24 Java HotSpot(TM) 64-Bit Server VM
20:30	brehaut	im out of ideas then sorry
20:30	crowbar	thanks for the help. do I need a clojars plugin? I've ready so many blogs and tutorials trying to learn compojure this weekend everything bled together.
20:31	brehaut	nope clojars should just work via maven plumbing
20:31	brehaut	crowbar: did you post about this on HN today?
20:31	crowbar	maybe :)
20:31	crowbar	small world.
20:31	brehaut	not really :P
20:32	brehaut	http://news.ycombinator.com/item?id=2430037 im presuming?
20:32	brehaut	i didnt know what you meant by over-hyped development style
20:32	crowbar	heh. yep. I've pretty much had a horrible time at every step in the process.
20:33	brehaut	i found that quite surprising; i have had basicly no trouble getting runnign with ring etc
20:33	crowbar	ring actually was easy.
20:33	brehaut	thats part of the magic of it :)
20:33	brehaut	ive not really used compojure myself
20:34	brehaut	so i dont know if thats been the source of your issues
20:35	crowbar	swank has been terrible. half the tutorials for it wanted me to run it in emacs, the other half say lein is what I should use. all the ring stuff is pretty straight forward. But then compojure stuff is spread over so many versions that it doesn't really help. I'm spoiled by the django tutorial.
20:35	brehaut	crowbar may i suggest hopping on #clojureql - you might get help with the specifics there if its not a lein issue
20:35	brehaut	crowbar: ok i have completely avoided swank
20:36	brehaut	crowbar: but from what i understand you should ignore every tutorial in the wild and follow the instructions in the README.
20:36	brehaut	crowbar: the django tutorial is pretty good
20:37	crowbar	I think I'm having just a general lein issue.
20:37	brehaut	crowbar: on the other hand, even from day one django was an order of magnitude and some larger than compojure. you really can learn a lot of how compojure works just by reading the source (theres about 200 lines)
20:37	znutar_	brehaut: mec: thanks!
20:40	znutar_	Is the super-pom.jar message something that pops up whenever lein can't satisfy deps? I got that earlier when I installed lein as root using macports and things were failing due to permissions issues
20:41	dnolen	crowbar: personally I prefer plain ring w/ moustache for routing. hiccup for simple templating things, enlive for more serious templating. that said there's nothing like Django yet, but Django has it's own pluses and minuses.
20:43	brehaut	enlive is a reason to persevere with clojure for web all by itself
20:48	Raynes	brehaut: Man, I'm writing some straight HTML for the first time in forever. :o
20:48	brehaut	Raynes: i do that all the time :P my latest blog post is 4500 words all manually marked up :P
20:49	Raynes	My blog posts are usually only slightly marked up.
20:49	brehaut	i often use markdown, but this one has diagrams
20:49	brehaut	and i did them with html and css
21:13	jweiss	is there really no way to conditionally add a key to a map literal? something like { :a :b :c :d (if blah (:d :e))} (i know that's not it, but just to give the idea of what i want)
21:14	jweiss	syntax quote and unquote splicing almost works
21:14	jweiss	but it doesn't
21:14	jweiss	,`{~@[:a b:]}
21:14	clojurebot	Invalid token: b:
21:14	jweiss	,`{~@[:a :b]}
21:14	clojurebot	1
21:17	mec	wow apparently lazy-seq binds recur :x
21:17	dnolen	jweiss: don't think that's possible, but I also don't see much benefit.
21:17	dnolen	mec: ?
21:17	mec	,(lazy-seq (recur))
21:18	clojurebot	Execution Timed Out
21:18	dnolen	,(recur)
21:18	clojurebot	Execution Timed Out
21:18	dnolen	mec: nothing to do w/ lazy-seq
21:19	mec	in my code i've got (fn blah [x] (lazy-seq ... (recur y))) and it says recur expects no args
21:23	gtrak	there might be a loop in the ...?
21:23	gtrak	.(recor)
21:24	gtrak	.(recur)
21:26	dnolen	mec: recur on lazy-seq doesn't make sense. lazy-seq computations are more general than recur.
21:27	dnolen	(fn blah [x] (lazy-seq ... (blah y)))
21:27	dnolen	mec: ^ is what you want.
21:30	mec	i have to do some extra computation inbetween the lazy-seq bindings
21:31	dnolen	mec: ? and what stops you from doing that?
21:37	mec	thats what the recur was for
21:38	mec	hang on i'll gist this
21:39	dnolen	mec: you can't use recur inside lazy-seq, there's no place to recur to.
21:40	mec	https://gist.github.com/912946
21:41	brehaut	mec: yikes!
21:42	mec	lol, i think i can just nuke the lazyness anyway since almost all of the calculation is done by the time the seq is created
21:43	brehaut	mec :when (identiy new-pos) is the same as :when new-post
21:44	mec	ah right, just blindly changed that from (filter identity)
21:44	brehaut	mec: well also new-pos is always truthy i think; only nil and false are falsy
21:44	mec	it could be nil if x or y are <= 0
21:45	brehaut	,(boolean [])
21:45	clojurebot	true
21:45	dnolen	mec: your code works fine for me.
21:45	mec	ya i added the loop, before it was just the fn
21:46	brehaut	,(boolean [(when (pos? -1) [1]) (when (pos? -1) [-1])])
21:46	clojurebot	true
21:46	brehaut	((juxt identity boolean) [(when (pos? -1) [1]) (when (pos? -1) [-1])])
21:46	brehaut	,((juxt identity boolean) [(when (pos? -1) [1]) (when (pos? -1) [-1])])
21:46	clojurebot	[[nil nil] true]
21:46	mec	dont forget the for pulls the vector apart
21:47	brehaut	ah true
21:57	mec	i feel this is overly complicated in general
22:07	devn	g'day all
22:18	crowbar	ARRRggg. Just realized the issue was that I have to disable ipv6 for java to reach the network.
22:18	crowbar	because I removed openjdk and install sun jdk by recommendation of some stupid blog that openjdk breaks clojure.
22:18	crowbar	Anyway, lein and clojars was not the issue.
22:23	amalloy	mec: you definitely can't recur across the boundary of a lazy-seq. it doesn't make sense
22:24	amalloy	the good news is, there's not really any reason to want to do so
22:24	mec	i know, i just forgot to add in a loop
22:26	amalloy	mec: incidentally, it looks like the pattern you're using in routes* is the same as the one i built a little abstraction for at https://github.com/amalloy/amalloy-utils/blob/master/src/amalloy/utils/seq.clj#L32
22:26	amalloy	i wonder whether having a loop/recur inside a lazy-loop/lazy-recur makes things less readable
22:27	mec	its that or get rid of the lazy and loop, but have to carry around a results vector
22:28	amalloy	mec: not really. you could drop the inner loop entirely
22:29	amalloy	(if (= 0 x y) (cons result-level (routes* queue-left)) (routes* (into queue-left ...)))
22:30	amalloy	since the loop target of your recur is at exactly the same place as the lazy-seq recur target; just don't cons anything if you want to keep going without adding a new result
22:33	mec	oh? i can do this immediatly in my code?
22:34	amalloy	indeed, the snippet i pasted should "just work"
22:34	mec	wow, so the lazy-seq just keeps calling that until it gets a value? no chance of a stack overflow?
22:34	amalloy	mec: that's the magic of lazy seqs
22:35	amalloy	it's effectively using the caller's stack frame as a trampoline
22:35	mec	huh never knew that, i thought it always had to return a value
22:36	amalloy	&((fn make-zero [x] (if (zero? x) [0] (make-zero (dec x)))) 10000)
22:36	sexpbot	java.lang.StackOverflowError
22:36	amalloy	hm
22:36	amalloy	hah forgot lazy-seq: ##((fn make-zero [x] (lazy-seq (if (zero? x) [0] (make-zero (dec x))))) 10000)
22:36	sexpbot	⟹ (0)
22:36	amalloy	an apt demonstration of the fact that it works, i guess
22:36	mec	very true
22:37	mec	so how does this work?
22:37	amalloy	mec: same way any lazy-seq works. it wraps up the body of the lazy-seq macro in a thunk, and returns that thunk immediately
22:37	amalloy	the caller sees it, notes that it's a lazy-seq, and asks it to force itself
22:38	amalloy	a thunk is immediately returned, which is forced...
22:38	amalloy	glossing over details there, but that's the general flow
22:43	mec	theres actually a couple places I can apply that little bit of knowledge to
22:46	mec	they did the exact same thing in Joy of Clojure ;p i wonder if they didnt know about it or just tired to keep things simple
22:47	amalloy	mec: loop/recur is surely faster. avoids creating and destroying stack frames
22:48	mec	ah i see
22:51	mec	looks like they are near identical in speed
22:53	zakwilson	I'm profiling some code I wrote with Yourkit and it seems to be spending most of its time doing swank.util.io/read-chars, but that makes no sense (it doesn't do anything with swank; swank just happens to be connected while I'm profiling it). Before I build a new jar without swank, is there a known issue?
22:54	mec	it could just be blocking on read and since its always sitting there just seems to take the most time
22:54	mec	but that is just completely a guess
22:59	zakwilson	Doesn't seem to do that if I profile it at idle, and the CPU-intensive stuff I'm profiling doesn't call anything from swank.
23:05	mec	amalloy: its weird but even when a lot of computation happens in the loop, the version without it is equal or faster
23:07	amalloy	mec: have you tried it using my lazy-loop? i'm interested to see if other people think it makes things more readable or less
23:08	zakwilson	At idle, it spends all its time doing java.lang.Thread.sleep(), which is expected.
23:09	mec	amalloy: thats instead of using route* right?
23:09	amalloy	yeah
23:09	mec	ok let me try it
23:17	mec	amalloy: i like it
23:17	amalloy	cool, thanks
23:18	mec	deffinitly beats having to put the args at the ass end of the fn
23:22	amalloy	mec: yeah, that readability improvement was a big motivator
23:24	mec	any other lazy tricks you'd like to share? :D
23:25	amalloy	mec: nah, lazy-loop is a pretty recent development for me. feel free to steal whatever you want from amalloy-utils though
23:58	mec	in emacs is there a way to auto indent 2 spaces anything with the form (fn [] instead of indenting to the leveling of the [