#clojure – 2009-06-27

2009-06-27

00:34	_hrrld`	I tried to post my first message to the google group today (about 4 hours ago) and it doesn't seem to have appeared. Is there often a delay?
00:34	_hrrld`	Or perhaps was I blocked as spam?
00:34	samjr	Anyone using JavaFX with clojure yet?
00:35	codyK	long delays arent unusual
00:35	_hrrld`	codyK: Thanks, good to hear.
00:37	Chouser	_hrrld`: your first post is held until rhickey approves it manually
00:38	_hrrld`	Oh. I hope he likes it. ;)
00:38	codyK	single moderator? sounds like a lot of work . . .
00:38	duck1123	_hrrld`: aside from determining if it's spam, he doesn't really judge
00:40	Chouser	codyK: only for first post per user. no manual intervention after that.
00:40	Chouser	rhickey has described it as "works well"
00:41	_hrrld`	Thanks for the insight.\
00:43	duck1123	the clojure list is busy enough. We don't need the spam.
00:45	codyK	2,000 messages is more than I'd want to look at, but if it works well for him, that's cool
01:07	jjttjj	hmm anyone happen to know why every time I use (flush) it screws up my REPL and doesn't work
01:09	slashus2	jjttjj: What screws up again it?
01:11	jjttjj	whenever I use flush followed by read-line, the REPL just keeps giving me blank prompts no matter what I put in
01:12	jjttjj	like it just doesn't respond to my input
01:12	jjttjj	and I'm copying the ported PCL word for word
01:12	slashus2	Seems to work for me.
01:12	jjttjj	hmmm
01:13	jjttjj	well, on a related note, if the slime REPL just keeps taking input without giving the "user>" prompt, is there a way to break out of that without restarting slime?
01:14	slashus2	I don't use slime. Maybe your problem is with slime and not clojure with the flush.
01:14	jjttjj	hmm maybe, i'll check it out
01:19	jjttjj	ok yep it's slime
01:19	jjttjj	thanks
08:28	blbrown_win2	anyone here. I want to be able to launch a cloure environment from clojure in a thread. I guess this should be easy to do? and the other thread won't share any of the same namespaces?
09:18	yangsx	Can anyone help me understand this: (my-fun (first aseq)) gives me correct result, but (map my-fun aseq) gives NullPointerException: clojure.lang.LazySeq.sval(LazySeq.java:47)
09:54	rhickey	yangsx: could you paste a reproducing snippet?
10:14	yangsx	rhickey: thanks, just found my error: it's because my misunderstanding of if-let
10:14	rhickey	yangsx: ok
10:21	yangsx	I still often assume CL's rule that empty sequence is nil/false and thought if-let will choose the other branch. That's a problem for me moving from CL to Clojure.
10:25	Jetien	hi, i couldn't find in the api how to convert a string to an int
10:25	Chousuke	Use java for that.
10:26	Chousuke	,(Integer/parseInt "10")
10:26	clojurebot	10
10:26	Jetien	thanks
10:27	Chousuke	the core lib avoids duplicating java functionality :)
10:28	Chousuke	Because of that, it helps to know the java standard library.
10:29	Chousuke	fortunately, it's quite well documented. :P
10:29	Jetien	mh i understand
10:29	Jetien	but what does (num) do then?
10:30	Chousuke	,(doc num)
10:30	clojurebot	"([x]); Coerce to Number"
10:30	Chousuke	hmm.
10:30	Jetien	yes i know, but what does this mean?
10:30	Chousuke	,(class (num 4))
10:30	clojurebot	java.lang.Integer
10:30	Chousuke	,(class (num "3"))
10:30	clojurebot	java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Number
10:30	Jetien	that's what i tried
10:30	Chousuke	it's a cast, not a conversion.
10:31	Jetien	ah, okay
10:36	lisppaste8	danlei pasted "ansi2html" at http://paste.lisp.org/display/82611
10:36	danlei	hm, can someone tell me, why this won't work?
10:39	danlei	ansi-code-to-tag does its job, but ansi-to-html won't close all open tags, if the 0 ansi-code is in the string
10:39	danlei	in the /same/ sting. it works, if the enclosing tag is in another invocation of a-t-h
10:42	danlei	(the messed up character in the paste is a literal escape)
11:44	jackdempsey	has anyone written up a little something on metadata? it seems so simple....you have a symbol foo, and to get its meta data you can call (meta foo) or ^foo
11:44	jackdempsey	but then when i get into looking at things like #^ i seem to trip myself up
11:44	jackdempsey	like there's metadata for objects and metadata for the compiler
11:45	jackdempsey	oops, heh, "objects"
11:46	duck1123	jackdempsey: chances are, you might be wanting with-meta if you want to attach metadata to your values
11:46	jackdempsey	i would expect after #^String foo that ^foo would show {:tag String} but it seems i'm definitely wrong there
11:46	jackdempsey	duck1123: yep, read over that last night and that seems to be where i trip up
11:46	jackdempsey	attaching metadata to values vs vars maybe?
11:47	jackdempsey	i think i also need to review symbols, vars, values, and variables.....maybe sure i get all of it
11:48	rhickey	http://groups.google.com/group/clojure/msg/919455504c57659e
11:48	duck1123	it always bothered my that with-meta put the metadata at the end
11:49	jackdempsey	thanks rhickey that looks great, appreciate it
11:51	danlucraft	is there a fn to find the type of a struct?
11:53	duck1123	danlucraft: they're all structs, but the type of struct is not recorded
11:53	jackdempsey	hmm interesting
11:54	duck1123	I ran into that issue myself
11:54	duck1123	I wanted to multimethod on struct type
11:54	danlucraft	duck1123: ah, ok. thanks.
11:54	jackdempsey	can we set! things with the bot here?
11:55	jackdempsey	,(set! warn-on-reflection true)
11:55	clojurebot	java.lang.IllegalStateException: Can't change/establish root binding of: warn-on-reflection with set
11:55	jackdempsey	k
11:55	danlei	what would be idiomatic clojure for something like this: (loop for (a b) on '(a 1 b 2 c 3) by #'cddr collect a collect (* b 2))? that is, processing every other element in a sequence, and returning it afterwards
11:55	kotarak	danlucraft: the usual approach is a type tag on the map itself or in the meta data.
11:55	jackdempsey	the #^ example in that email was interesting....that a reflection warning is shown when just (.length (identity foo))
11:55	jackdempsey	but not when (.length #^String (identity foo))
11:56	kotarak	danlei: (map processor (take-nth 2 stuff))?
11:56	danlei	kotarak: I'll try. the expression i showed would return (a 2 b 4 ...
11:56	danlucraft	kotarak: well, I don't think metadata would make sense because I want them to be practically different objects
11:57	danlucraft	so I'll use a :type key I suppose
11:57	duck1123	,(binding [warn-on-reflection true] (.length (identity "foo")))
11:57	clojurebot	3
11:57	kotarak	,(mapcat (fn [[a b]] [a (* b 2)]) (partition 2 (list :a 1 :b 2 :c 3)))
11:57	clojurebot	(:a 2 :b 4 :c 6)
11:58	danlei	kotarak: thanks
11:58	kotarak	,(let [l (list :a 1 :b 2 :c 3)] (interleave (take-nth 2 l) (map #(* % 2) (take-nth 2 (rest l)))))
11:58	clojurebot	(:a 2 :b 4 :c 6)
11:58	kotarak	danlei: dunno which is better
11:58	fffej	is anyone looking at the ICFP contest in Clojure? I'm making slow (but steady!) progress here and wondered if anyone wanted to pool efforts!
11:59	danlei	hm, liked the first one better somehow :) ty
11:59	danlei	(partition was what I should have known ...)
12:19	jackdempsey	duck1123: thanks....why doesn't that warning surface
12:19	jackdempsey	when not passing in #^String
12:19	jackdempsey	(not even sure what that warning really means, but googling :-) )
12:25	Chouser	fffej: is it right now??
12:25	fffej	it's happening now yeah
12:26	fffej	I have some truly terrible Clojure code that implements the VM that it requires
12:26	Chouser	hmph. Well, I guess not. I was hoping to have a little time for the contest, but I don't think it'll happen this weekend.
12:33	danlei	is there a way to use partition like this: (partition 2 '[a 1 b 2 c]) -> ((a 1) (b 2) (c nil)) ?
12:35	danlei	otherwise, I'll just check, if the sequence's length is un-even, and append nil
12:35	Chousuke	danlei: not yet :)
12:35	danlei	Chousuke: ok, ty
12:36	Chousuke	danlei: partition will get padding in 1.1 though. there's an open bug on it.
12:36	danlei	Chousuke: very nice
12:37	Chousuke	but, grumble at google groups
12:37	Chousuke	it swallowed my reply :(
12:38	Chouser	partition with padding is in git master
12:38	Chouser	(partition 2 2 [nil] '[a 1 b 2 c])
12:45	Chousuke	okay, what the hell
12:46	Chousuke	I'm not seeing my posts on the group :(
13:34	lisppaste8	danlei annotated #82611 "ansi2html" at http://paste.lisp.org/display/82611#1
13:35	danlei	anything unindiomatic in there?
13:36	danlei	especially, is an atom the way to go for closing-tags?
13:40	danlei	well, if nobody critisises
13:41	danlei	it's either perfect, or such a mess, that no one even tries to comment on it :)
13:48	Chousuke	m
13:48	Chousuke	hm
13:48	Chousuke	I'm pretty sure you could do away with the atoms
13:48	Chousuke	-s
13:52	danlei	how exactly? i tried with vars and set! but that gave me an error
13:54	danlei	like: can't change the root binding
13:55	Chousuke	well, I'm thinking of doing a reduce with an accumulator for the closing tags.
13:56	Chousuke	but I can't quite figure out how to modify the code to do that.
13:56	danlei	hm ... sounds nifty
14:07	Lau_of_DK	Good evening gentlemen
14:18	krumholt	Hello, can someone make a simple example of the difference between alter and commute?
14:20	Lau_of_DK	The difference is that multiple commutes to guarantee that they're executed in the sequence that they were evaluated, alter however protects the order
14:20	Lau_of_DK	s/to/dont
14:33	Chousuke	danlei: do you have a test string I could use with that thing=
14:43	krumholt	thanks
14:45	danlei	Chousuke: sure, for example: (ansi-to-html "[1m[5mfoo[10mbar[0mbaz[37mqux") => "<b><blink>foobar</blink></b></font>baz<font color=white>qux" after that, (a-t-h "0mquux") => "</font>quux"
14:46	danlei	that is, in emacs, C-q ESC [ <code> m for the ansi-codes
14:52	danlei	hm ... that first </font> shouldn't be there, actually
14:54	danlei	ah, was left from a previous test.
14:56	Chousuke	okay
14:56	Chousuke	my version appears to work
14:57	danlei	just annotate my version, if you will
14:57	lisppaste8	Chousuke annotated #82611 "stateless" at http://paste.lisp.org/display/82611#2
14:57	Chousuke	it's not that much more readable but...
15:01	Chousuke	ansi-code-to-tag actually has a misleading name now. it returns a [text-accumulator closing-tags] pair
15:01	danlei	i see. takes a litte for me to grasp it, but It's an educating read
15:03	danlei	It'll take me some time, to get used to write in that style.
15:04	Chousuke	the reduce returns a pair of [text-chunks leftover-closing-tags] which are concatenated and then stringified
15:06	danlei	I see, and it's something I can learn from. If you saw that code in the wild, which version would be easier for you to read? Where do you see the advantages?
15:06	Chousuke	well, my version is a pure function
15:07	Chousuke	it won't have any mishaps with state like your atom-version did when you pasted your examples :)
15:07	Chousuke	otherwise, neither of them are particularly simple :P
15:07	danlei	well, the thing is: I want the function to keep state
15:07	danlei	because it is feed with strings from a socket
15:08	danlei	*fed
15:08	Chousuke	well, in that case you can remove the (str* ...) part from the ansi-to-html function
15:08	Chousuke	in which case it'll return a [text, closing-tags] accumulator which you can use as a starting value for another reduce
15:09	danlei	so you'd close over such a text, closing-tags pair?
15:10	danlei	I'll spend some time with your code to fully grasp it, it really is a good example for me
15:23	lisppaste8	Chousuke annotated #82611 "chopped up a bit" at http://paste.lisp.org/display/82611#3
15:23	Chousuke	danlei: ^^
15:24	danlei	Chousuke: :) was just hacking up on it :)
15:24	Chousuke	actually hm, chunk-string should have the two-argument version arglist reversed so it can be used with reduce
15:25	danlei	what I'm trying to do is have make-ansi-to-html-converter, letting it return a closure which keeps the context and can be fed with strings
15:25	Chousuke	then you could do (reduce chunk-string [[] '()] ["foo" "morefoo" "evenmorefoo"])
15:26	Chousuke	but that'll still break if the strings are broken in a way that the regexp fails :/
15:27	Chousuke	but that was a problem with the original too :)
15:27	danlei	yes, it is
15:27	danlei	it's used in a mud client, btw
15:27	danlei	but, as of now, it's still pretty basic
15:28	Chousuke	it sounds like you ought to ensure that the full string is received before converting it to html
15:28	danlei	hm ...
15:29	Chousuke	or at least that it doesn't contain broken ansi sequences
15:29	Chousuke	that method will likely be simpler than hacking ansi-to-html to support broken sequences :)
15:29	danlei	yes, I do see the problem, but how should I know, when the string is "finished"?
15:30	Chousuke	that I suppose is a protocol problem :P
15:30	danlei	:)
15:31	danlei	anyway, I thank you for the time you spend doing your solution, it really is appreciated
15:31	Chousuke	no problem. it was fun anyway :)
15:31	Chousuke	finding functional solutions to stateful problems is always fun
15:31	danlei	I'll spend some more time with it, and later I'll decide, which version to include. somehow I like the idea of having a converter-maker :)
15:32	Chousuke	You should try to avoid state. your program is basically the definition of a function :)
15:32	danlei	about the protocol: at least, in most MUDs ansi-sequences are left to the magicians, so, if it fails, I'll know whom to blame :D
15:32	Chousuke	it gets input, processes it, and produces output
15:32	Chousuke	no need for state.
15:33	danlei	well, the state is there, but it's kept on the stack, isn't it?
15:33	Chousuke	well, it's "state", but it's not mutable :)
15:34	danlei	yes
15:34	danlei	one question, that also is important for me: which version will I be able to understand better, say, after two years
15:34	Chousuke	since you'll be doing IO you will have some mutable state too but you should isolate that from the actual processing logic
15:34	danlei	which is no criticism, but just a practical consideration
15:35	Chousuke	Heh, well, I'd bet on the functional version.
15:35	danlei	:)
15:35	Chousuke	mutable state always complicates things
15:35	Chousuke	you actually need to care about how a function affects it, instead of what its inputs and outputs are.
15:35	danlei	are you sure about the "always"?
15:35	Chousuke	yes. :)
15:36	Chousuke	sometimes you can't avoid it though :/
15:36	danlei	hm, I'm not. but I'm willing to change my opinion over time. In general, I am with you, but always is pretty often, innit? =)
15:36	Chousuke	well, yeah
15:37	danlei	at the moment, I'm taking it as a lesson. You provided another view at the problem, which I just solved, as I would have solved it in CL.
15:38	danlei	(more or less)
15:38	Chousuke	well, you basically used a mutable stack. I replaced it with an accumulator parameter
15:38	danlei	yes
15:39	Chousuke	though since you're doing parsing, you might want to take a look at fnparse
15:40	Chousuke	it's a third party library for writing functional parsers.
15:40	danlei	that's what I meant. Your version's state is encapsulated in the function itself, as the arguments of sucessive calls. In my version, state is kept at another place.
15:40	danlei	fnparse?
15:40	danlei	I'll check up on it
15:40	danlei	ty
15:41	Chousuke	danlei: the problem with your version is that there's no referential transparency. a previous call to your function may affect the following ones; something that you want to avoid
15:42	Chousuke	if you call your function twice with the same arguments, the results might not be the same.
15:42	danlei	in general, yes. if I make a make-converter, returning functions which close over the state, I have the re-invocability, and the encapsulation. I guess that would be a nice solution
15:43	Chousuke	it's not very idiomatic for clojure though :/
15:43	danlei	hm
15:43	danlei	why exactly?
15:43	Chousuke	well, your functions still encapsulate mutable state.
15:44	danlei	yes, but in a more encapsulated, "tidier" manner, I'd say
15:44	Chousuke	if you call make-converter, feed it a string, and then the same string again, the output may still differ, right?
15:44	danlei	like a little chunk of mess :)
15:44	danlei	yes, it's not a pure function, I agree
15:44	Chousuke	danlei: it's a lot like OOP :)
15:44	danlei	it's OOPs twin :)
15:45	danlei	whether the evil, or the good one :)
15:45	Chousuke	anyway, my general advice is to avoid any mutable state until you truly need it.
15:46	Chousuke	you simply won't need to care at all about what a function does if it's pure :)
15:46	duck1123	which one has the mustache? That's how you can tell
15:46	Chousuke	which is not the case if you encapsulate mutable state
15:47	danlei	you see, I do agree with you
15:47	danlei	I'm just not sure, if the generality of the statement applies
15:47	danlei	but who am I. we can discuss that again, when I'm more familiar with that style,
15:48	Chousuke	heh
15:48	danlei	until then, I'll have a bias toward things I do already understand well ;)
15:48	Chousuke	have you read http://clojure.org/state ?
15:48	danlei	yes, but it's been a while and I'll re-read it
15:48	danlei	but, for example:
15:49	danlei	if mutable state was generally wrong, why would rich allow it?
15:49	danlei	there seem to be situations, where it's just te better solution, don't you agree?
15:49	Chousuke	I'm sure you'll grow to appreciate functional style a great deal if you stick with Clojure. :)
15:49	danlei	(don't wanne be heretic)
15:49	Chousuke	danlei: well, yes. some things are inherently stateful
15:50	Chousuke	your ansicode->html transformer however, is inherently a functional problem.
15:50	danlei	point taken
15:51	danlei	for the most part, I already stick with functional solutions
15:52	Chousuke	the stateful part of your problem is the network IO, I suppose.
15:52	danlei	I guess it's been the problem at hand, which made me use a known solution ... habits :)
15:52	clojurebot	People have a problem and think "Hey! I'll use a regular expression!". Now they have two problems....
15:52	danlei	clojurebot: botsnack
15:52	clojurebot	thanks; that was delicious. (nom nom nom)
15:52	Chousuke	but if you isolate the transformation from the IO, I think you will have a much more robust program :)
15:52	duck1123	I don't have much experience with them, but would this be a good job for monads?
15:52	Chousuke	possibly.
15:53	Chousuke	I'm still not comfortable with monads though :/
15:53	danlei	are monads idiomatic style in clojure?
15:53	duck1123	I wish Programming Clojure had covered monads. Here's hoping for the next book
15:53	Chousuke	danlei: well, yes.
15:53	Chousuke	danlei: monads are purely functional after all
15:53	Lau_of_DK	clojurebot: seen eyeris?
15:53	clojurebot	eyeris was last seen quiting IRC, 1242 minutes ago
15:55	danlei	I think I haven't even understood the basic principles of them. I know there used to keep side-effects and functional code separate.
15:55	danlei	but /how/, I don't know
15:55	Chousuke	danlei: though you don't have to use them -- unlike haskell -- because Clojure is impure, and you can separate stateful logic from functional logic simply with discipline
15:55	duck1123	there was a good series on monads in clojure, but my head started spinning halfway through
15:56	danlei	at the google group?
15:57	duck1123	I think it was this one: http://onclojure.com/2009/03/05/a-monad-tutorial-for-clojure-programmers-part-1/
15:57	duck1123	perhaps I should try reading it again.
15:57	danlei	http://tinyurl.com/cfr9le
15:57	danlei	yes, just found it
15:58	danlei	thanks
15:58	danlei	going to be a tough read, I guess :)
15:58	danlei	I'll give it a try
16:01	danlei	(and have a look at that fnparse thing)
16:02	Chousuke	using the state monad you could rewrite the transformation functions so that the state (the accumulator) is encapsulated away, but still functional
16:03	Chousuke	that is, without resorting to atoms or other mutable state trickery :)
16:12	danlei	there is to much knowledge missing, right now. I'll have to read up on it ... But one further question: If you're so convinced of /pure/ functional code, what exactly keeps you using clojure, and not some language like haskell? (I, for one, have dabbled a little with it, but found it somehow ... just to "strict" for my taste. A subjective statement, I know ...)
16:14	danlei	(atm common lisp and clojure are the languages I prefer, and then there's a huge gap ...)
16:30	duck1123	personally, I don't like languages where indentation is significant
16:30	duck1123	that was what turned me off to python as well
16:30	danlei	hm .. I think that's optional in haskell
16:32	duck1123	I've only read a little bit into Haskell. Seems like a decent language, but I'm happy with Clojure for the time being
16:32	fffej	it's funny how indentation isn't significant in Lisp, but everyone does it the same way anyway
16:32	danlei	you mean: emacs does it the same anyway =)
16:32	kencausey	yes, no more consistent than in most other languages
16:32	duck1123	right, I do whatever emacs does for me
16:33	Chousuke	fffej: indentation is very significant in lisp for readability though.
16:33	fffej	exactly my point
16:34	fffej	(if indentation turns you off Python, it could turn you off lisp too)
16:34	Chousuke	I have noticed that instead of looking at the parentheses I get all the needed information from the indentation :P
16:34	Chousuke	the parentheses kind of disappear
16:34	eevar	wonder if i'm not missing out on something tho. there has to be a reason for why people use (oca/s)ml and haskell
16:34	danlei	I agree, lisp in general is great. But now, that there's clojure I find myself missing each others features in both of them :)
16:36	eevar	there are too many languages out there, and not enough time :/
16:36	duck1123	I like that (in clojure-mode at least) I have control over the "shape" of my code by deciding where i put the newlines
16:36	kencausey	sexps to the rescue
16:38	danlei	apropos features in cl/clojure ... is something like cl's debugger planned for clojure? that's one of the things I miss. (yes, know about the possibility to attach debuggers, but it's just not the same)
16:38	Chousuke	hmm :/
16:39	Chouser	danlei: I don't think rhickey plans to create such a thing, but it seems likely you could.
16:39	Chouser	use the JVM debugger api (whatever that is) and just do it.
16:39	danlei	Chouser: I fear, I don't have the skills to tackle such a thing
16:40	duck1123	I've been wanting to try out cljdb, but I couldn't figure out how to get it working with maven
16:40	danlei	that'd be a fairly advanced project, I guess
16:40	danlei	not one of the things I can hack up in a few weeks
16:41	danlei	(one of the major problems my not really knowing java)
16:42	danlei	but in general, yes, I'd be willing to offer my work/time for such a project (with someones more knowledgeable by my side)
16:43	fffej	putting type hints in programs in annoying - would (in theory) it be possible to annotate functions with metadata about types (in Clojure core) and use type inference to insert the necessary casts automatically? It seems like it should from my basic understanding, but before I go off to read more about Hindley–Milner inference, I wondered if there were any holes in that plan?
16:45	danlei	would some of you guys be interested in such a project? (cl-like debugger for clojure)
16:47	Chouser	danlei: I must admit I've never used a cl-like debugger, so I only have a vague sense of what that means.
16:48	danlei	Chouser: well, you can select stack frames, see local vars, evaluate expressions within a stack-frame, and so on. everything built into the language itself. (you'd just have to fire up clisp or something and have a look)
16:48	Chouser	fffej: one issue to keep in mind is the dynamic nature of clojure programs. just because (defn foo [] 5) alreays returns an Integer right now does not mean it will throughout the life of the program.
16:48	fffej	chouser: thanks, that was the dose of reality I needed :)
16:48	danlei	and, of course, the error messages are a lot more telling than some java-related messages I get sometimes in clojure
16:49	danlei	but I'm not sure how to do that, without the condition system
16:49	danlei	you're offered different restarts (restartable conditions), which you can choose
16:49	Chouser	fffej: you're alreays (???) welcome.
16:54	danlei	in general, the debugger is a kind of global handler, which opens up, if a sent (error-)condition is not bound to a restart, or some other code which handles it. so in the debugger, you become somewhat a "human" handler, which can decide, what to do. you always can set up a handler in code, which knows, how to decide and restart the code further down the calls (where the restarts are set up for it)
16:55	danlei	if a condition is not handled in the code (via handler-bind for example), you'll have to do it "by hand", in the debugger
16:57	danlei	so the condition system, on top of which de debugger is the "last resort" is kind of a superset of java
16:57	danlei	*java's exceptions
16:57	danlei	(as far as I can tell)
17:01	danlei	. o O (now I've made them all fall asleep :)
17:02	Chouser	I wonder if the java debugger api (I say that as if I knew it existed) allows you to catch an exception at it's moment of creation such that it could be continued right there.
17:02	Chouser	I wouldn't be surprised if the answer was "no", in which case the project may be doomed already. :-)
17:02	danlei	unfortunately, I have no idea (my java knowledge is very basic)
17:04	danlei	but, as I said, my offer stands: if someone wants to tackle it, I'll be glad to help (don't know how much that's worth though :) )
17:04	kotarak	Maybe one can modify throw (the Clojure one) to drop into a debugger.
17:07	danlei	the basic principle (don't think I formulated it well) are: a function which does something generally knows, how to back up in case of an error. let's say a read error: read another file, try reading same file again, enter values manually. then, further up the calls, it's known /how/ to handle best, which of the offered restarts would be best. the handler now chooses a restart, which fits. if there is no handler, which chooses in the
17:07	danlei	code, you'll drop into the debugger, and choose yourself. (think, that is a better explanation than the one above)
17:08	danlei	so there are three parts: the condition, the restart, and the handler
17:11	Chouser	danlei: much of that (not including the interactive debugger part) has been implemented in contrib.error-kit
17:11	duck1123	wasn't there a contrib library that was working towards something like this?
17:11	danlei	Chouser: thanks for the pointer
17:11	Chouser	...though I'm not sure I endorse it anymore.
17:13	Chouser	it's explicitly an attempt to provide (some of) the features of the CL conditions system, but I think in the process I brought over unnecessary baggage (esp. object-system related cruft).
17:13	danlei	(now I've collected pretty much stuff, that I'll have to have a look at today :)
17:14	danlei	well that's another discussion: If one /wants/ a cl-like condition-system and debugger
17:15	danlei	I, for one, find it pretty useful
17:17	danlei	but then, one can't have the cake and eat it too. there is a kinda long list of things, I would love to have in CL from clojure, and vice-versa. (keyword arguments in clojure, more general sequence abstractions in CL for example)
17:18	danlei	everything is somehow a compromise ...
17:18	duck1123	doesn't defk try to do the keyword argument thing?
17:19	danlei	for inclusion in core?
17:19	danlei	that'd be very nice to have IMHO
17:19	duck1123	IIRC, c.c.def/defk
17:20	duck1123	haven't gotten around to using it yet, but I have a few functions where it might fit
17:20	danlei	you're not alone ;)
17:20	kotarak	defnk.
17:21	kotarak	(defnk foo [a b c :x default-for-x :y default-for-y] ...) (foo some-a a-b another-c :y 5)
17:23	danlei	I'd love to see something like this in core ... Things like :from-end-t, :key, etc. are a nice thing to have, imho. you get used to it ;)
17:23	duck1123	I wonder though if using defnk might be overkill for what i needed
17:23	danlei	like ... garbage collection is overkill for most c-programmers? ;)
17:24	kotarak	duck1123: multi-arity also helps sometimes: (defn foo ([x] (foo x some-default-y)) ([x y] ...))
17:24	danlei	things like that shouldn't be done by hand everytime, I think
17:25	danlei	it's just sad, that many (if not all) of the discussion at c.l.l are rants, rants and ... more rants
17:25	duck1123	I did some pseudo-keyword arguments for my fork of clj-record
17:25	danlei	when both languages are actually so nice ...
17:26	kotarak	danlei: instead of wasting time with c.l.l one should program in CL or Clojure. That is a much better of the time...
17:27	danlei	well, I do, with my mud-client, for example (which is not that much, but some friends do actually use it) as far as c.l.l. goes: you really can learn an awful lot over there, but signal/noise is not that high, unfortunately
17:28	duck1123	Has anyone else found that since learning clojure they can't read a java book without mentally converting the code samples to clojure?
17:28	danlei	and the threads about clojure were especially disgusting, IMHO
17:30	dmiles_afk	danlei: i am working ona secondlife client that uses Clojure
17:30	duck1123	dmiles_afk: will it support opensim?
17:30	dmiles_afk	i presently test on OpenSim about 60% of the time
17:31	dmiles_afk	since there are little nits between them
17:31	danlei	dmiles_afk: very nice, atm, I've enough work with the text thingy (and learn a lot, for example the discussion with chosuke)
17:32	dmiles_afk	its funny.. i've one arround text and network things like openmemtavere.. it's funny the text one isnt much easier ;P
17:32	duck1123	dmiles_afk: do you have a public repository anywhere?
17:32	danlei	:)
17:33	dmiles_afk	duck1123: http://code.google.com/p/opensim4opencog/
17:33	duck1123	thanks
17:33	dmiles_afk	the clojure stuff: http://code.google.com/p/opensim4opencog/source/browse/trunk/bin/cogbot.lisp
17:34	dmiles_afk	setj = set, progn = block. i am trying to make the code feel more common lispy.. so been trying to avoid name conflicts
17:35	kotarak	danlei: the function or the macro version?
17:36	danlei	anyway, thanks for the discussions, guys. learned a little today. afk
17:36	duck1123	so do you CL'ers find much use for I think it was called PROGV?
17:36	danlei	kotarak: macro, quick and dirty
17:36	duck1123	there was a post on the things this guy didn't like about clojure, and the missing progv was one of them
17:37	danlei	duck1123: for interpreters, I think. haven't actually used it, besides for educational purposes.
17:37	duck1123	The only way I could think to do it in clojure was to use eval
17:37	dmiles_afk	i use ikvmc.exe to compile clojure.dll .. but for everyday testing i use DotLisp.dll (clojure's predicessor)
17:37	kotarak	duck1123: If it's the Var/pushThreadBindings thing: yes, I needed that already several times.
17:38	dmiles_afk	clojure on .NET i am hoping will be able to call events code
17:38	dmiles_afk	events are methodlists that you call one method.. but it fires to several methods
17:41	dmiles_afk	what .NET has on the JVM is the ValueTypes which is the deatch of many JVM languages
17:41	dmiles_afk	yet however everythiong .NET i've used is still much slower than JVM based things :)
17:42	dmiles_afk	thats not just mono.. its even win64.NET vs Sun
17:43	dmiles_afk	but i am not trying to bash one or the otehr.. its just JVMs only 7 valuetypes makes things harder in the long run
18:22	jackdempsey	just a general comment, but damn, there really are some practical features in closure
18:22	jackdempsey	can tell it wasn't designed by committee in an ivory tower.
18:24	cgrand	quidnunc: haven't had time to check text-node before, it was plain broken. sorry :-(
18:25	cgrand	quidnunc: (select (html-resource (java.io.StringReader. "<html><b>hello<abbr>wrld")) [:abbr :> text-node]) works now
18:31	quidnunc	cgrand: Thanks
18:34	quidnunc	I feel a little less stupid for not being able to get it working
18:37	durka42	is there like a map difference function?
18:38	durka42	as in, take this map and remove the key/value pairs where the keys are in this other map
18:38	durka42	that was not very articulate
18:38	durka42	(map-difference {:a 1 :b 2 :c 3} {:a 42 :c 1}) => {:b 2}
18:39	durka42	hmm, in writing out that example i realized this isn't the function i'm looking for...
18:40	duck11231	move along
18:40	opqdonut	:P
18:44	Chousuke	,(reduce dissoc {:a 1 :b 2 :c 3} (keys {:a 3 :c 2})); anyway :)
18:44	clojurebot	{:b 2}
19:12	jackdempsey	hmm
19:13	jackdempsey	is there another more union related way ? set algebra? cant' think of the words atm
19:14	Chouser	relational
19:14	jackdempsey	haha, whew, yes
19:14	Chouser	:-)
19:15	Chouser	jackdempsey: for differences?
19:15	jackdempsey	yep
19:16	jackdempsey	the dissoc felt more like take this map and remove the elements with these keys
19:16	Chouser	there's clojure.set/difference, but that operates on sets
19:16	jackdempsey	gotcha yeah, makes sense there
19:17	Chouser	I think dissoc is exactly how you get a map with something removed. shrug
19:17	jackdempsey	i'm so used to thinking "hash" and with the function "map", thinking of maps always gets a bit backwards in my head
19:17	jackdempsey	yep, no that makes sense, with difference for sets
19:53	bpattison	I want to "update" a value of a give key in a struct-map, is there a function that will allow me to do and return an updated copy of the original or do I need to reset all the values from the original?
19:54	drewr	,(doc update-in)
19:54	clojurebot	"([m [k & ks] f & args]); 'Updates' a value in a nested associative structure, where ks is a sequence of keys and f is a function that will take the old value and any supplied args and return the new value, and returns a new nested structure. If any levels do not exist, hash-maps will be created."
19:55	bpattison	drewr: excellent -- thanks
19:56	drewr	,(update-in {:foo {:bar {:baz 1}}} [:foo :bar :baz] inc)
19:56	clojurebot	{:foo {:bar {:baz 2}}}
19:57	drewr	,(update-in {} [:foo :bar :baz] #(or % (inc %)))
19:57	clojurebot	java.lang.NullPointerException
19:57	duck1123	assoc should also work if the value is at the top
19:58	Chousuke	hmm
19:58	bpattison	yeah, its just a simple struct-map
19:58	Chousuke	,(update-in {} [:foo :bar] (fn [] 1))
19:58	clojurebot	java.lang.IllegalArgumentException: Wrong number of args passed to: sandbox$eval--4429$fn
19:58	Chousuke	,(update-in {} [:foo :bar] (fn [_] 1))
19:58	clojurebot	{:foo {:bar 1}}
19:59	Chousuke	ah, right, you should've used and, not or :)
20:01	bpattison	I guess I was looking for something like (setter gc :x (inc x 1)) where gc is a struct-map
20:02	Chousuke	that's not really a "setter"
20:02	Chousuke	since it doesn't modify anything :)
20:02	bpattison	sure -- but something that acts like a setter
20:02	Chousuke	well, update-in works
20:03	Chousuke	or just assoc
20:03	bpattison	okay, I'll give those a try
20:04	bpattison	yep, assoc works perfectly
20:04	Chousuke	structmaps are just normal maps that you can generate optimised getters for
20:04	Chousuke	there's usually no reason to use them at all.
20:04	Chousuke	still for some reason, they're popular
20:05	Chousuke	I guess the structmap base key definition has documentation value, but... :)
20:06	bpattison	well that's why I used it -- the "struct" has meaning
20:07	bpattison	plus, doesn't it provide a defined hash structure that get's defaulted if key values aren't initialized?
20:07	Chousuke	it's no different from a map
20:07	Chousuke	(:foo {})
20:07	Chousuke	,(:foo {})
20:07	clojurebot	nil
20:07	Chousuke	same happens with a struct map
20:08	Chousuke	I suppose the other nice thing about struct maps is that you can create them with (struct foo some vals here)
20:10	Chousuke	but that may actually be less readable than explicitly specifying the keys
20:10	Chousuke	though it saves a bit of typing
20:38	Mark_Addleman	hi, i've got a question about walking parallel lists using for... suppose i've got two lists, a and b. a=[1 2 3] and b=[a b c]. i want to walk them in parallel (not nested) using a list comprehension. something like (for [x a, y b] (x y)) -> (1 a 2 b 3 c)
20:39	Mark_Addleman	i don't know how to construct the binding to do anything other than nesting. i thought about a function to interpose elements of a with b, but i couldn't find a core/contrib function to do that
20:39	Chousuke	interleave
20:39	durka42	,(map list [1 2 3] '[a b c])
20:39	clojurebot	((1 a) (2 b) (3 c))
20:39	Chousuke	for can't do parallel walking
20:39	Chousuke	(doc interleave)
20:39	clojurebot	"([& colls]); Returns a lazy seq of the first item in each coll, then the second etc."
20:40	Mark_Addleman	ah, that's perfect. thanks!
20:57	durka42	,(with-out-str (.write out 65) (.write out 0) (.write out 66))
20:57	clojurebot	"A
20:57	durka42	^ is this a bug?
21:01	kyle_burton	question re: serializatino of object graphs with both clojure and java data types in them - I'm sure there is logic behind it, does anyone know the ratinoale for keywords (:foo) not being serializable?
21:02	Chouser	durka42: I think that's an encoding thing
21:03	Chouser	character encoding
21:03	durka42	but why did it never print the closing quote?
21:06	Chouser	durka42: I'm not sure yet, but the \0 code must be telling it somehow that the " should not be printed. The final \n as well, in my tests.
21:07	Chouser	no, I'm wrong.
21:07	Chouser	,"a\000bcdefghijkl"
21:07	clojurebot	"a
21:48	dreish	That prints as "a^@b" in my Aquamacs.
21:49	Chouser	dreish: that sounds better than what I see
21:49	dreish	What are you using to run your repl?
21:50	dreish	I've got Aquamacs, a fairly recent 1.1.0 alpha, and Java 1.6.
21:51	Chouser	ah, rlwrap changes things
21:51	dreish	And I'm using Inferior Lisp.
21:52	durka42	grumble grumble
21:53	durka42	why doesn't dataoutputstream use overloading
21:54	Chouser	just java on a linux command-line...
21:55	Chouser	(print "a\000bcdef\000ghi") ==> abcdefghinil
21:55	Chouser	oh, the nil is the return value
21:55	Chouser	so the nil chars are just ignored
21:55	dreish	Well, they're non-printing.
21:55	Chouser	indeed
21:55	dreish	Same with any other language.
21:56	Chouser	(prn "a\000bcdefghij") ==> "abcdefghij"
21:56	durka42	i guess somewhere between sockets, nailgun, vim and vimclojure somebody stops on nulls
21:57	dreish	perl -e 'print "a\x00b\n"' => ab
21:58	Chouser	adding rlwrap causes it to stop after at the null char
22:06	Chouser	it would be nice if null string printed an escaped form, line \newline does
22:07	dreish	Same with the various other non-printing chars, like 1, 2, etc.
22:08	Chouser	yeah. there are a few, but more would be better
22:08	dreish	,(char 2)
22:08	clojurebot	\
22:08	Chouser	,(pr-str (char 12))
22:08	clojurebot	"\\formfeed"
22:10	Chouser	"\f"
22:10	Chouser	,"\f"
22:10	clojurebot	"\f"
22:10	Chouser	,(nth "\f" 0)
22:10	clojurebot	\formfeed
22:48	Mark_Addleman	hi, i've got a question using destructuring in a for macro. (for [[a b c] [1 2 3]] nil) -> "java.lang.UnsupportedOperationException: nth not supported on this type: Integer"
22:48	Mark_Addleman	i'm trying to get a binding of 1->a, 2->b, 3->c. it seems to work in let, but not for
22:49	Chouser	right, because for destructures each item in the seq
22:49	Chouser	not the whole seq
22:50	Chouser	,(for [[a b c] [[1 2 3] [4 5 6]]] b)
22:50	clojurebot	(2 5)
22:50	Mark_Addleman	i'm struggling to understand what that means... does that imply (for [[a b c] [[1 2 3]...) ?
22:50	Mark_Addleman	ah, i think i got it
22:57	Mark_Addleman	ok, this is coming to me slowly (sometimes agonizingly!). i have two lists: a list of database tables and another,parallel list, of primary keys. i want to walk the lists in parallel so i get a pairing of table & primary key. how can i do this?
22:58	Mark_Addleman	,(for [[t pkey] [[:t1-table :t2-table] [:t1-pkey :t2-pkey]]] [t pkey])
22:58	clojurebot	([:t1-table :t2-table] [:t1-pkey :t2-pkey])
22:58	Mark_Addleman	i want ([:t1-table :t1-pkey] [:t2-table :t2-pkey])
23:04	Chouser	'for' can't do it by itself
23:06	Mark_Addleman	i'm not wedded to for :) is there a parallel list walking function in the core library or in contrib? I couldn't find one. i found "walk" but that doesn't seem to do what i want either
23:06	Chouser	map
23:06	Chouser	,(for [[a b] (map vector [1 2 3 4] [5 6 7 8])] {:a a, :b b})
23:06	clojurebot	({:a 1, :b 5} {:a 2, :b 6} {:a 3, :b 7} {:a 4, :b 8})
23:08	Chouser	,(map + [1 2 3 4] [5 6 7 8])
23:08	clojurebot	(6 8 10 12)
23:09	Mark_Addleman	ok. i get it. it would have taken me a long time to come up with that on my own. thanks
23:10	Mark_Addleman	i'm at the neophyte stage: i understand the little bits but not how to put them together in interesting ways yet
23:10	Mark_Addleman	anyway, thanks for the pointer
23:10	Chouser	not a problem
23:10	Chouser	it's fun stage but won't last long. :-)
23:13	Mark_Addleman	i hope not! right now, i'm pushing myself through the frustration. the examples on the forum as well as this channel have been enormously helpful
23:38	agc	hello