#clojure – 2008-09-08

2008-09-08

10:42	Chouser	what percentage of a struct-map has to be nil before it's less efficient than a sparse hash map (roughly speaking, on average).
10:43	rhickey	Chouser: less efficient in what way?
10:44	Chouser	I was thinking space.
10:44	Chouser	memory
10:45	Chouser	Relative lookup performance between the two would be roughly the same regardless the size, wouldn't it?
10:45	rhickey	yes
10:46	rhickey	not a percentage thing, really. absolute sizes matter
10:47	Chouser	oh, ok.
10:47	Chouser	In this particular case I've got a total of about 6 or 7 keys, but for any one instance I'd expect about half of them to be nil
10:48	rhickey	would the keys be in the hash-map or not?
10:48	rhickey	key set to nil value and no key are different
10:48	Chouser	oh, right, in the hash-map they'd be half empty. In the struct-map they'd be half nil.
10:49	Chouser	In this case I don't need to differentiate.
10:50	rhickey	struct-map is likely to be smaller, but you'd have to look at the implementation or measure to know
10:51	Chouser	is there an easy to way to ask a collection for its size in bytes?
10:51	Chouser	probably a Java question, I guess.
10:51	rhickey	no
10:51	rhickey	but another key question is - how many instances of the same struct?
10:52	Chouser	one per XML node. So... shrug
10:52	Chouser	likely hundreds. Maybe thousands.
10:53	rhickey	then the shared keys will win
10:54	Chouser	ok, thanks.
10:54	rhickey	no substitute for profilng - speaking of which, I wonder if cemerick had any luck with profilers?
10:56	cemerick	rhickey: yourkit and good ol' hprof work fine; netbeans chokes when attempting to profile our largest project that has some clojure in it, although it does fine on a toy project that uses clojure (and on our largest project from before we started using clojure).
10:57	cemerick	obviously, I'd like to use NB exclusively, but I've not been able to come up with a simple way to replicate the problem so as to report a bug
10:58	rhickey	cemerick: by 'work fine' do you mean you can collective meaningful data on Clojure fn calls etc, not just Clojure's Java runtime?
10:59	cemerick	rhickey: well, clojure fns and such appear on their own as distinct call sites, if that's what you're getting at.
10:59	rhickey	yes, that, getting number of calls, time spent in, time spent in children etc
11:00	cemerick	yeah, the clojure fns are identified nicely, as far as I've seen. Obviously, the names aren't as spiffy (my-fn is labelled myfn_1234 or whatever), but it's definitely usable.
11:01	rhickey	cool
11:01	cemerick	Yourkit is very nice, although being able to use NB would be great.
11:01	rhickey	agreed
11:02	rhickey	I guess VisualVM is in same boat as NB
11:02	cemerick	How to isolate its problem is entirely unclear to me...
11:03	cemerick	Hrm, hadn't come across VisualVM before, thanks.
11:03	cemerick	But yeah, being on NB, I would expect it to have the same hang-ups.
11:17	blackdog	rhickey, http://lambda-the-ultimate.org/node/2978
11:17	rhickey	blackdog: saw that, thanks
11:17	blackdog	k
11:18	rhickey	no controversy, so everyone must agree :)
11:18	blackdog	:) waiting for the fireworks
11:20	Chouser	LtU is a bit slanted toward static typing, isn't it? Gives them more problems to solve and might make Clojure too boring to cause controversy.
11:20	cemerick	"...its target focus is concurrency..." Funny, as we've not really touched the concurrency stuff at all.
11:21	cemerick	LtU has been pretty balanced over the years, IMO.
11:21	Chouser	ok. I read it, but must admit to understanding a pretty small fraction of the issues that are brought up.
11:27	rhickey	Chouser: yes, LtU has lots of category theory etc, Lisp is very old school for them, although they did cover PLT Scheme's move to immutable cons cells: http://lambda-the-ultimate.org/node/2631 :)
11:29	rhickey	cemerick: yeah, FP is good for concurrency but not only that. Few people understand how their mutable state effects everything
11:31	Chouser	"Let's make a programming language!" on LtU -- haha! so doomed!
11:31	rhickey	I'm happy for the coverage and the nice writeup
11:31	cemerick	While concurrency safety is a Good Thing, it might be worthwhile to ensure that clojure isn't pigeonholed as "only" being useful for concurrent programming. Of course, that sort of PR and expectations management is only important if a broader audience for clojure is desired.
11:33	rhickey	cemerick: it's pretty easy to show someone how mutable objects make concurrency hard, much more subtle to have them understand the complexity issues of state raised by 'Out of the Tar Pit'.
11:33	rhickey	a broader audience for Clojure is desired :)
11:34	cemerick	rhickey: I wouldn't deign to assume something like that, especially since Clojure's interoperability with Java could enable it to fly under the radar in perpetuity. :-)
11:34	Chouser	That's a demure Rich Hickey form of Torvald's goal of taking over the world.
11:35	rhickey	Clojure will always be for discriminating tastes, but I'd like to saturate that market
11:36	Chouser	Ruby was relatively unknown until Rails. I think it's just a matter of time until there are one or two analogous "killer apps" for Clojure to catch people's attention.
11:39	cemerick	I'm deeply pessimistic about the ability of a non-curly-brace language becoming widespread anytime soon (outside of those with "discriminating tastes" , perhaps ;-))
11:39	pjstadig	clojure's way of dealing with concurrency is what caught my attention
11:39	rhickey	Clojure has curly braces!
11:40	cemerick	:-P
11:40	pjstadig	don't know if that will translate into a "killer app", but with multi-core procs and the complete inability of most other languages to deal with concurrency, it might
11:41	Chouser	I'm here (originally) because of Java libs + macros.
11:41	rhickey	Chouser: so how have you found the functional programming side?
11:41	Chouser	oh, and dynamic types too, I guess.
11:41	pjstadig	yeah (in my short time getting acquainted with clojure) there are lots of selling points to clojure
11:42	Chouser	rhickey: yummy.
11:42	rhickey	That's what I hope for Clojure, but it's hard to sell - FP will make your code better, easier to understand, easier to test, easier to change
11:43	rhickey	as FP langs go Clojure is IMO the most approachable
11:43	pjstadig	i don't know ML or Haskell, but i've tried to get acquainted
11:43	pjstadig	and Clojure is more approachable IMO
11:43	rhickey	but I don't think people are looking for FP, just suffering from OO mess...
11:44	Chouser	I think I cut the necessary immutable programming neural pathways in Scala (solving projecteuler problems), but had to use mutable structures pretty often for performance.
11:44	pjstadig	the blip vids are great though
11:45	pjstadig	someone passed them along to my Ruby Users Group
11:46	Chouser	And Scala's static typing annoyed me deeply as soon as I tried to do anything real. In Clojure, the types stay out of your way and there's really deep and rich support for immutable programming (collections, library of functions, idioms, etc.
11:46	Chouser	)
11:46	rhickey	Chouser: they're working on it:http://www.codecommit.com/blog/scala/more-persistent-vectors-performance-analysis :)
11:46	cemerick	yeah, I came by way of Scala too
11:48	Chouser	I got to Scala by way of Rhino. :-)
11:50	rhickey	Chouser: so with ClojureScript you'll get back to Rhino?
11:51	Chouser	heh. no.
11:52	Chouser	I was in Rhino because of Yegge (of course) -- a year or so ago, I agreed with nearly everything he said. But that was before I realized he's not promoting JavaScript, but rather his own new language based vaguely on JavaScript and built on top of Rhino.
11:55	Chouser	although I suppose testing ClojureScript by running the results on Rhino might be handy.
11:56	blackdog	what is clojurescript a clj to js translator then? does code exist?
12:12	Chouser	yes, that's what it would be. There is some very preliminary code, but I don't think anyone's actively advancing it.
12:13	blackdog	is that in contrib ?
12:13	Chouser	blackdog: no. Let me see if I can find a link.
12:17	Chouser	blackdog: http://groups.google.com/group/clojure/msg/73fdae1e56ffae71
12:17	blackdog	thanks
12:19	pjstadig	dumb question
12:19	pjstadig	what is the best way to exit the REPL
12:19	pjstadig	(quit) (exit) don't seem to work
12:19	pjstadig	^C?
12:19	Chouser	^D
12:20	pjstadig	thanks
12:20	Chouser	Or (System/exit 0)
12:21	pjstadig	you mean (. System exit 0)?
12:21	pjstadig	(System/exit 0)
12:21	pjstadig	java.lang.Exception: No such namespace: System
12:21	Chouser	cgrand: hi! Any recent changes to your Javascript HTML templating stuff?
12:22	Chouser	pjstadig: Yeah, if you've got an older Clojure. In oldest to newest:
12:22	Chouser	(. System exit 0) (.exit System 0) (System/exit 0)
12:22	pjstadig	oh ok
12:23	pjstadig	i've got the download snapshot
12:23	pjstadig	from june i think
12:23	Chouser	sorry, I rapidly lose track of which changes were made how recently.
13:50	albino	Has clojure chosen a convention for word separation in variable names? camelCase or under_scores ?
13:51	rhickey	dashes-please
13:51	albino	oh duh, lisp
13:52	albino	next newbie question, how do I do else if
13:52	Chouser	(if <test> <then-clause> <else-clause>)
13:53	albino	I'm lookinng for something like (if <test> <body> elif <test> <body> else <body>)
13:54	rhickey	albino: cond
13:55	albino	rhickey: thanks
14:02	rhickey	http://www.reddit.com/r/programming/comments/7031x/maybe_building_a_new_language_on_a_homemade_vm/
14:09	Chouser	your willingness to read and respond to reddit comments demonstrates impressive patience.
14:10	rhickey	Chouser: it's interesting to see the level of animosity towards the JVM
14:14	pjstadig	well there's that, and people also seem to be missing the thrust of the argument
14:14	rhickey	pjstadig: yes, that's frustrating
14:14	pjstadig	which is not necessarily that the JVM is The Way (TM), just that it may be smarter to not start from scratch
14:21	Chouser	does anyone agree with zzzeek's comment that many Java libraries are sub-par in some way compared to libraries for other languages?
14:22	Chouser	I guess poor API doesn't bother me much since slapping a pretty Clojure API on top usually requires only a little code.
14:22	Chouser	But having had fairly little experience with Java, I don't know if I should be worried about buggy or poorly-performing libs.
14:23	blackdog	certainly clojure gets round all my issues with the java infrastructure(barring egregious memory use)
14:24	rhickey	Chouser: any such blanket comment is suspect, I doubt all Java libs are bad nor all Python libs good
14:24	blackdog	i think it's the extra scaffolding required of java that people hate, and that disappears with clojure
14:25	blackdog	i.e. it's not really the libraries
14:25	rhickey	also he did some EJB, which is particularly painful, and SOAP
14:25	Chouser	I know from experience that not all Python libs are good, but those that are bundled with Python are generally sufficient and generally very trustworthy.
14:26	rhickey	I did some playing (in Clojure) with JMS and OpenMQ and it was awesome, easy, fun and vert fast, with pro level docs from Sun
14:26	Chouser	If SAX weren't standard, available in most platforms, and just as bad in all of them, then the nastyness of SAX in Java would worry me more.
14:27	rhickey	What's the Python alternative to JMS?
14:27	blackdog	you can use the stomp protocol from various clients inc python
14:27	blackdog	apachemq supports it
14:28	rhickey	blackdog: yeah, apache activemq is Java/JMS
14:30	blackdog	if you mean a python like implementation of a jms server then i don't know
14:34	blackdog	actually maybe twisted python has some protcol
14:34	Chouser	avoid twisted.
14:34	Chouser	twisted is actually what I was specifically thinking of when I said "not all Python libs are good" :-)
14:34	blackdog	:) i use it for a chat server
14:38	rhickey	I don't wan't to beat up on Python, just to highlight JMS and Servlets say, as great examples of Java APIs that are simple, general, and most important support many implementations: JMS has OpenMQ/ActiveMQ/JORAM, servlets: Tomcat/Jetty/Glassfish/Resin, all free, + many commercial
14:38	rhickey	These are not toys
14:41	blackdog	i think for anyone considering clojure for commercial work
14:41	blackdog	the jvm is a terrific choice
14:41	blackdog	it's an easy sell to customers
14:41	blackdog	for academic work etc, purity maybe not
14:42	rhickey	blackdog: what do you mean by purity?
14:43	blackdog	well people on that thread seemed a bit academic to me, there was a particualr quote
14:43	blackdog	which made me say purity there
14:45	blackdog	for example, people talking about the abstraction is java underneath
14:46	blackdog	and then talk of assembler being the ultimate abstraction
14:46	blackdog	etc
14:52	Chouser	the i86 instruction set doesn't support TCO either, does it?
14:53	rhickey	Chouser: everything is manual at that level.
14:54	rhickey	turtles all the way down matters when you are writing the whole stack. But Clojure isn't writing its own GC, so the fact that the JVM guys use Java/C/ASM doesn't matter to me
14:55	Chouser	I'm probably betraying vast ignorance here, but if you were to emit i86 asm, you could use the processor's own call stack but then you wouldn't get TCO.
14:56	blackdog	or me, that was my point, the other stuff is academic argument while we get to write code now
14:59	rhickey	Chouser: you would be defining your own calling convention and could easily (manually) do TCO, just clear stack before jumping
15:01	Chouser	ah, you can't jump into a Java function? you must call?
15:03	rhickey	Chouser: yeah, that's all abstracted away, the instructions are high-level, like invokeVirtual
15:03	rhickey	you can't fudge the stack at all
15:03	Chouser	there's goto, but only within a function?
15:04	rhickey	Chouser: right
15:04	pjstadig	is there a preference between 'clj' and 'clojure' when naming libraries, executables, etc.?
15:04	pjstadig	clojure-extra vs. clj-extra
15:05	rhickey	pjstadig: unless you are planning a contribution to Clojure, you should avoid using it to avoid conflict with the base libs
15:06	pjstadig	i mean just a project name
15:06	pjstadig	on github you see projects like clojure-mcp, clj-cont, etc.
15:08	rhickey	I guess clj- is like the J all java libs prepend, but you should avoid Clojure, reserved for the language itself.
15:09	pjstadig	yeah or i was thinking maybe clj- is the equivalent of cl- for common lisp
15:09	pjstadig	just curious
15:09	rhickey	also now there is a package/namespace unification, so com.pjstadig.libname
15:10	pjstadig	oh
15:10	pjstadig	cool
15:10	abrooks	rhickey: Is that documented on the main website or only in the Google Group? :)
15:11	rhickey	abrooks: it's been evolving on the group and here, but I hope to cut a release now that it has settled down, with docs on the web
15:12	abrooks	rhickey: Cool. BTW, I just noticed the "Recent Changes" link on the website. Good idea. Is there an RSS feed for website changes?
15:13	abrooks	Oh, I see that the RSS feed for the changes page is the website changes.
15:13	StartsWithK_	rhickey: is there maven repository or something similar with clojure.jar from current trunk?
15:14	rhickey	StartsWithK_: not from me, but probably
15:15	abrooks	Sorry, should have looked first. Maybe that could be a discrete link (currently it's only provided via the linkrel).
15:15	abrooks	(changes RSS--^)
15:18	rhickey	abrooks: I don't know, this just falls out of the Wiki software, maybe tomhickey knows...
15:18	rhickey	abrooks: in any case, between releases the changes are mostly doc bug-fixes, not tracking SVN
15:18	albino	(doseq i "hello" (if (= i "h") (println "match"))) Why doesn't that print match?
15:19	Chouser	albino: a string is a sequence of characters
15:19	Chouser	but "h" is a string
15:19	Chouser	try \h instead
15:19	albino	ahh, characters are different from strings, thanks
15:20	Chouser	Yep. (class "hi") ==> java.lang.String
15:20	Chouser	(class \h) ==> java.lang.Character
15:21	leafw	is there any reason why the following fails: (pop (seq (double-array 10)))
15:22	leafw	java.lang.ClassCastException: clojure.lang.ArraySeq$ArraySeq_double cannot be cast to clojure.lang.IPersistentStack
15:23	abrooks	rhickey: Oh, I know. I'm interested in generally tracking website changes too. Had I been subscribed to the recent changes feed I would have seen that the link to the recent changes page was added on 8/9. Hm. That's a little chicken-and-eggy isn't it...
15:23	Chouser	leafw: any reason not to use "rest" instead of "pop"?
15:23	leafw	no reason. Just testing
15:24	leafw	I would like to understand how is pop different than rest.
15:24	leafw	peek also fails in the same situaton.
15:25	Chouser	sure. peek and pop operate on IPersistentStack
15:25	leafw	that is evident from the cast error.
15:25	Chouser	ArraySeq extends ASeq, but not IPersistentStack
15:25	leafw	but what do you mean?
15:26	leafw	perhaps my question ought to be reformulated: why should there be different treatment of sequences?
15:26	Chouser	yeah, that's a deep enough "why" that I don't think I can help you. :-)
15:27	Chouser	With persistent collections, is there ever any different between peek/pop and first/rest?
15:27	leafw	if by persistent you mean immutable, no, they both return a new collection anyway.
15:28	Chouser	And yet rhickey implemented IPersistentStack, so I must be missing something.
15:28	Chouser	oh, wait, I figured this out once...
15:29	Chouser	(pop [1 2 3]) ==> [1 2] (rest [1 2 3]) ==> (2 3)
15:30	Chouser	not the same
15:30	leafw	hum
15:31	leafw	weird. So vectors are treated differently.
15:31	Chouser	so peek/pop don't operate on seqs in general, but on specific data structures that support it.
15:31	Chouser	...while all collections support first/rest
15:31	leafw	yeah, like a java.lang.Vector (or whatever it is that Cloujure uses in replacement)
15:32	leafw	so vectors are more like linked lists then
15:32	leafw	like cons cells chained.
15:32	Chouser	vectors support peek/pop in the opposite direction as first/rest. lists support them in the same direction. maps and ArraySeqs don't support them at all.
15:33	leafw	ArraySeq is new to me.
15:34	leafw	thanks Chouser, you did cast some light.
15:34	Chouser	there's actually lots of little seq classes to implement seqs around various underlying data structures.
15:37	rhickey	Chouser: all coolections support seq, which in turn supports first/rest
15:38	rhickey	leafw: no, vectors are most like arrays/arraylists, not chained, fast indexed access
15:38	rhickey	peek/pop work on the same end as conj
15:38	rhickey	first/rest always at front
15:38	rhickey	conj on lists is at front, on vectors at end
15:38	Chouser	well... first/rest (the clojure functions) call seq on their arg, right?
15:39	rhickey	right, but the collection only need implement seq
15:39	Chouser	ok
15:39	rhickey	first/rest are provided by the seq, while peek/pop are provided by the collection
15:40	rhickey	peek/pop return the same type of collection, first/rest always return seqs
15:40	rhickey	so, many differences
15:40	albino	If you wanted to the equivalent of a = b = 0 from a C like language. I tried this, but it doesn't seem to work (def a (def b 0))
15:41	rhickey	albino: def returns the var, not the value
15:42	rhickey	at top level (def b 0) (def a b)
15:42	rhickey	in a fn (let [b 0 a b] ...)
15:43	albino	rhickey: thanks
15:46	albino	is there a nice way to read from stdin, or do I just follow the same way that java would?
15:49	Chouser	you might look at slurp
15:49	Chouser	oh, nm.
15:49	Chouser	you want line-at-a-time, the whole stdin to EOF, or what?
15:50	albino	yes, read one line at a time from stdin
15:50	albino	In python I would say for line in sys.stdin: print line
15:51	albino	I'm looking for the equivalent
15:51	kotarak	Maybe line-seq, but you need a BufferedReader
15:52	albino	kotarak: that should work, thanks
15:52	kotarak	That leads me to another question: If I use line-seq with split-with. Are the lines read into memory? Or is this done only, when a access the two seq I get back?
15:53	rhickey	kotarak: enough is read to find the split point
15:54	kotarak	rhickey: Hmm.. Ok. Thanks.
15:54	Chouser	(require '[clojure.contrib.duck-streams :as ds])
15:55	Chouser	(doseq line (line-seq (ds/reader System/in)) (println line))
15:56	Chouser	yeah, it causes a bunch of Java io pain to evaporate.
16:00	Chouser	well, I finally checked in clojure.contrib.lazy-xml
16:01	Chouser	please hold your applause until the end of the show. ;-)
16:01	abrooks	Chouser: Cool. Has it changed significantly since X months ago?
16:01	Chouser	abrooks: it works now, but otherwise no.
16:02	Chouser	It'll use a pull parser if it's in the classpath, otherwise it does some ugly threading and weakreference stuff to tame the built-in SAX parser (or any SAX parser you hand it).
16:03	abrooks	Oh the original parser was greedy, right?
16:03	Chouser	Either way, the API is the same and you end up with a clojure.xml compatible tree of hashes and lazy-seqs.
16:03	Chouser	abrooks: yep
16:03	abrooks	This one is sort of lazy it sounds.
16:04	Chouser	the only other API difference (so far) is that emit doesn't add extra newlines unless you ask it to.
16:05	abrooks	Chouser: Is with_pull.clj the lazy pull parser?
16:05	abrooks	Oh, no. It's just a wrapper.
16:05	Chouser	I want to add more complete namespace support and maybe a more compact data structure (as has been discussed), but I wanted to make sure I got at least this much out there.
16:06	Chouser	yeah, I didn't write my own parser.
16:06	abrooks	Chouser: By compact you mean terser for readability concerns that you and I've discussed or something else?
16:07	Chouser	a single vector (or lazy-cons) per element instead of a hash and a vector.
16:08	Chouser	It would also help with readability, but I now think that's secondary -- providing converters that may or may not be triggered automatically may be sufficient.
16:11	meredydd	Ooh, wow. defonce is in SVN? Lovely.
16:15	meredydd	What's the current status of SQL in clojure? Is contrib's sql module the latest word, or is something else being mooted/cooked up elsewhere?
16:18	rhickey	meredydd: what do you want that jdbc doesn't do?
16:18	meredydd	Well, pool connections
16:19	meredydd	But, generally speaking, I'm looking for a Clojure-idiomatic way of doing things
16:19	rhickey	resultset-seq
16:19	meredydd	If there's nothing already out there, then I'll get on with writing my own wrappers
16:19	meredydd	Where does that live?
16:20	rhickey	boot.clj
16:21	meredydd	Excellent. Thank-you.
16:23	rhickey	meredydd: http://commons.apache.org/dbcp/
16:31	meredydd	Gah. Dodgy wireless routers suck.
16:31	meredydd	rhickey: Did you say anything else since you recommended dbcp?
16:31	rhickey	nope
16:32	rhickey	not a recommendation, just a pointer. I presume you're not in Tomcat or another app server with connection pooling
16:32	blackdog	another good one is http://proxool.sourceforge.net/
16:33	meredydd	Right now, I'm in Compojure
16:35	meredydd	(Aiee. It's an Apache Commons project, all right. The basic version of the setup involves factory methods, registration, and all sorts of dependency injection - and the "easier way" is 28 lines of extremely verbose XML.
16:36	blackdog	try proxool, it's transparent
16:37	Chouser	meredydd: that's your proof that it's not a toy
16:37	blackdog	a special jdbc:proxool url with yout db of choice
16:37	meredydd	Chouser: Really don't get me started.
16:37	meredydd	One of the nastier experiences of the last two months was starting a new project, and moving from Apache XML-RPC v2 to v3.
16:39	blackdog	http://proxool.sourceforge.net/quickStart.html
16:40	meredydd	Thank-you, blackdog.
16:46	wwmorgan	rhickey: the print method in clojure.lang.RT ought to check whether its argument is a Pattern and emit such forms like #"foo"
16:57	albino	How do I invoke a some clojure code outside of the repl? I was hoping to do java -cp /path/to/clojure.jar /path/to/code.clj
16:58	Chouser	close. Just add clojure.lang.Repl between .jar and .clj
16:58	Chouser	or clojure.lang.Script if you don't want to drop to a Repl when the .clj is done.
16:59	albino	Chouser: thanks
16:59	Chouser	http://en.wikibooks.org/wiki/Clojure_Programming#Installation_from_Source
17:00	Chouser	are you on a unix?
17:01	albino	gentoo linux
17:01	Chouser	rhickey: someone wrote a defmulti version of print, didn't they? Is that planned for inclujion?
17:01	abrooks	Chouser: If only we knew some Gentoo devs who could get Clojure into portage....
17:02	albino	has someone already packaged it?
17:02	Chouser	albino: in that case you may be interested in http://en.wikibooks.org/wiki/Clojure_Programming#Shebang_Scripting_in_Clojure as well
17:02	albino	Chouser: thank you
17:02	albino	I'll be using that for sure
17:02	abrooks	albino: Oh, it wouldn't be hard. I think I even started an ebuild at some point.
17:03	abrooks	I think I'd block it on having a better shell wrapper. The current one is... not so good.
17:03	Chouser	abrooks: you don't like rlwrap?
17:04	abrooks	Chouser: Oh, rlwrap is okay. I still want a context sensative REPL but that's neither here nor there.
17:04	albino	abrooks: you a gentoo dev?
17:05	abrooks	albino: No. I've been dangerously close at times. I work for a company that use Gentoo as a meta distribution (and also have been using Gentoo since who-knows-when).
17:06	albino	abrooks: nice
17:06	albino	In that case I volunteer abrooks before myself for packaging clojure
17:06	albino	that was easy enough
17:06	abrooks	I hang out with a number of Gentoo/ex-Gentoo devs on- and off-line.
17:07	Chouser	mostly ex- now
17:07	pjstadig	what about debian?
17:08	abrooks	I'll wait for the next release since that seems imminent.
17:08	pjstadig	anyone have enough experience to build a .deb?
17:08	abrooks	Chouser: I think it's still more current than ex- but I could be wrong.
17:09	albino	I'm sure if I took some time I could build a deb, these days I'm supposed to be getting good at rpms
17:11	albino	abrooks: cause they're brain dead, or what?
17:11	abrooks	I suppose one can be "good at potato sack racing"...
17:12	abrooks	albino: :)
17:29	albino	If anyone wants to make fun of some clojure code I wrote, I'm looking for feedback http://paste.lisp.org/display/66505
17:33	meredydd	Okay...
17:33	meredydd	Your big issue here is that you keep wanting to use mutable variables.
17:34	albino	meredydd: teach me
17:34	meredydd	What you wrote is more or less a Clojure transliteration of what you'd do in a (pardon me) 'normal' programming language.
17:35	meredydd	A good start would be to completely eliminate all (def)s from that code.
17:35	albino	how would I fit immutability in with solving this problem?
17:35	meredydd	They (re)define global variables
17:35	meredydd	In my experience, there are two uses of this kind of thing.
17:35	albino	but making them local, still isn't the right way, right?
17:36	meredydd	One, you do right at the top, there - you use a def to assign a name (stdin) to the result of a big hairy expression
17:36	meredydd	There's no need to define a global variable to do that - you can just use (let). So:
17:37	meredydd	(let [stdin (...big long hairy expression here)]
17:37	meredydd	...carry on and work with stdin here... )
17:37	albino	the gain being that I'm not defining another global variable?
17:38	Chouser	that's not the moste terrible use of def, though. The ones inside doseq is much worse.
17:38	meredydd	the gain being that you're recognising that 'stdin' is an immutable name for something, and that it's locally scoped. (let) has those characteristics.
17:39	Chouser	sorry for the snipe -- gotta go. :-/
17:39	meredydd	cya, Chouser
17:40	meredydd	Now, as Chouser says, the real issue is that you're using (def) to create a variable whose value changes
17:41	meredydd	which is something that's deliberately ugly in clojure, because it's so un-clojure-ish.
17:41	meredydd	albino: Still with me?
17:42	albino	meredydd: yes
17:43	meredydd	Okay. In the functional world, we think of recursive solutions as much as possible, rather than iteratively changing things.
17:43	meredydd	Let's start with a much more simple example - the classic factorial one.
17:44	meredydd	(1! = 1, 2! = 2 * 1, 3! = 3 * 2 * 1, 4! = 4 * 3 * 2 * 1, ...)
17:44	meredydd	Now, if you were doing that in Java, you might do something like:
17:44	meredydd	void fact(int n) {
17:44	meredydd	int val=1;
17:45	meredydd	for(; n>=1; n--) { val = val * n; }
17:45	meredydd	}
17:45	meredydd	Yes?
17:45	albino	yes
17:46	meredydd	Now, in Clojure, we would do something more like:
17:46	meredydd	(defn fact [n]
17:47	meredydd	(if (= n 1)
17:47	meredydd	1
17:47	meredydd	(* n (fact (dec n)))))
17:48	meredydd	Do you understand how that works?
17:56	albino	yeah, uses recursion
17:58	meredydd	right
17:58	meredydd	The point is that, instead of changing the value of 'n'
17:58	meredydd	what you do is go into a new frame, with 'n' having a different value.
17:59	meredydd	Now, in practice you'll use a bit of a cheat to account for the fact that you can't have an infinite number of stack frames
18:00	albino	are frames cheaper in functional languages and that's why that approach is chosen more often?
18:01	meredydd	Not so much. It's actually a conceptual choice - when writing large programs, it very quickly gets a hell of a lot easier to use functional techniques than standard mutable state
18:01	meredydd	(let alone if you're doing something like multithreading)
18:01	meredydd	so, the fact that functional runtimes often use tricks to keep stack frame usage low is a consequence of that philosophical approach
18:02	meredydd	Clojure has (recur), which is a special form.
18:04	meredydd	oh, blast.
18:04	meredydd	I'm sorry - I have to go now.
18:04	albino	np
18:04	albino	thanks for the info
18:04	albino	much appreciated
18:04	meredydd	Try looking for an "introduction to functional programming" article
18:05	rhickey	albino: here are some more tips:
18:05	rhickey	split your function into 2 - one that calculates a result and another that prints it. Combining the two will always make a mess
18:06	rhickey	give the value-calculating function a good name so we know what you are trying to do
18:07	albino	okay, that's easy enough
18:07	albino	didn't figure it was worth it for such a short problem
18:07	rhickey	make sure both functions take args (i.e. don't hardwire your global name)
18:08	rhickey	albino: functions will make it easier to do the right thing, but not longer in the end
18:09	wwmorgan	albino: if you had a function that took a string and produced a sequence of nesting levels for each character in the string, ie "(((a)))" yielded (1 2 3 3 2 1 0), then your problem becomes easy: for each line, paren-count is the last element in that sequence, and paren-depth is the max element
18:09	wwmorgan	*eg
18:16	wwmorgan	rhickey: the print method in clojure.lang.RT ought to check whether its argument is a Pattern and emit such forms like #"foo"
18:22	fyuryu	if anybody is interested in a processing wrapper, here's one: http://bit.ly/3ZT3ZG
18:24	fyuryu	I wanted to push it to github but git+ssh+windows apparently don't get get along
18:42	meredydd	fyuryu: I think the best thing might be to post a link to the Google Group
18:45	fyuryu	meredydd: yeah, I'm doing it now