#clojure – 2008-07-02

2008-07-02

01:27	Lau_of_DK	How do I compile my .clj file into a singla .jar file?
01:27	Lau_of_DK	(replace \a \e)
01:29	Lau_of_DK	How do I compile my .clj file into a singlr .jar file?
01:30	Lau_of_DK	(replace \r \e)
01:44	Lau_of_DK	k, nobody knows... When we refer to Trees, are we generally talking about hash-maps?
02:44	perspectivet	quick newbie question
02:45	perspectivet	how do I replicate c-style "while( x() ) { y(); }?
02:46	Lau_of_DK	Check the loop / recur documentation
02:47	Lau_of_DK	(loop [x y z] ( x() y() (recur (new x) (new y) (new z))
02:49	cgrand	perspectivet: can you give more details on what you try to achieve? In FP most functions take arguments and those which don't are constant.
02:51	perspectivet	I'm tranlating the following swt snippet into clojure
02:51	perspectivet	;; Display display = new Display ();
02:51	perspectivet	;; Shell shell = new Shell (display);
02:51	perspectivet	;; Text text = new Text (shell, 0);
02:51	perspectivet	;; text.setText ("ASDF");
02:51	perspectivet	;; text.setSize (64, 32);
02:51	perspectivet	;; text.selectAll ();
02:51	perspectivet	;; shell.pack ();
02:51	perspectivet	;; shell.open ();
02:51	perspectivet	;; while (!shell.isDisposed()) {
02:51	perspectivet	;; if (!display.readAndDispatch ()) display.sleep ();
02:51	perspectivet	;; }
02:51	perspectivet	;; display.dispose ();
02:52	cgrand	ok, I'm reading it (next time use http://paste.lisp.org/new/clojure for pasting code)
02:52	perspectivet	sorry
02:53	perspectivet	will do
02:54	lisppaste8	perspectivet pasted "swt snippet tranlation" at http://paste.lisp.org/display/63147
02:54	perspectivet	that's things so far
02:55	cgrand	ok: java interop so FP rules don't apply there :-) In that case loop/recur is the simplest way to go
02:56	perspectivet	cgrand: yeah, I figured. I'm coming over from the haskell world as far as recent fp experience goes and I couldn't find an api for any of the approaches I would use there.
02:58	lisppaste8	cgrand annotated #63147 with "added translation for the while" at http://paste.lisp.org/display/63147#1
03:01	cgrand	perspectivet: so as you can see my answer to your original question is (loop [] (when (x) (y) (recur)))
03:08	jgrant	cgrand : do you know of a way to create a jar of a clojure script/s ?
03:14	Lau_of_DK	Quoting cgrand
03:15	Lau_of_DK	for the jar file structure: copy clojure.jar and
03:15	Lau_of_DK	open it, name you main file "user.clj" and put it in the directory where boot.clj is. Edit
03:15	Lau_of_DK	the manifest file to point to clojure.lang.Script instead of clojure.lang.Repl as the main
03:15	Lau_of_DK	entry point for the jar.
03:15	Lau_of_DK	if you havce to load other files from
03:15	Lau_of_DK	user.clj, use (. clojure.lang.RT loadResourceScript "xxx.clj")
03:16	jgrant	thx
03:16	perspectivet	on a related note, is there a way to standard way to ship compiled clojure files?
03:17	perspectivet	btw: thx cgrand
03:17	jgrant	yea where are the compiled class files that clojure generates ?
03:18	jgrant	(seems like that would be a much 'saner' approach)
03:21	Lau_of_DK	I dont know - I would like to know,Im missing (save-lisp-and-die)
03:22	jgrant	now if only sbcl was as stable as the jvm ;)
03:23	perspectivet	is there an emacs mode with automatic-paste-lisp-org-paste or somesuch?
03:53	cgrand	jgrant: compiled class are never written to disk (except for genclass) and even if they were, they wouldn't be usable as-is because there's some close cooperation (can't give more details: I'm not Rich) between the class loader and the class to close over the environment
03:56	hoeck	mhh, would it be possible to save an image of the jvm?
04:12	Lau_of_DK	Theoretically at least, it should be possible
04:22	cgrand	hoeck: volunteering to test how http://cryopid.berlios.de/ interacts with the JVM? ;-)
04:25	Lau_of_DK	cgrand, that looks sweet, but its not fully ready yet, would you mind finishing it, so we can toy with it tonight?
07:56	cemerick	Am I right in thinking that it's totally OK to throw an UnsupportedOpEx from ISeq.cons?
08:14	rhickey	what seq doesn't support cons?
08:22	rhickey	cemerick: deriving from clojure.lang.ASeq will give you cons and much more for free
08:25	cemerick	rhickey: A half-hour ago, I hadn't noticed ASeq :-)
08:26	cemerick	but, FWIW, it doesn't make sense to cons onto this particular seq (a resultset of sorts -- not from a SQL query, but similar in concept)
08:27	rhickey	yeah, someday there will be JavaDoc... until then, everyone should be aware there are abstract helper bases for most of the persistent data structures
08:28	rhickey	cemerick: the sensibility seems, to me, to be in the eyes of the conser, not the consee
08:29	cemerick	rhickey: True enough. That's sometimes hard to see when one is playing both sides of the fence.
08:29	rhickey	:)
08:48	cemerick	This might be unreasonable given the current impl, but would be nice in some circumstances to have full destructuring available in def.
08:48	cemerick	s/would/it would
08:48	rhickey	in order to def more than one thing at a time?
08:57	cemerick	rhickey: Yeah, I have a couple of situations where I'm doing stuff like (let [{foo :foo bar :bar baz :baz} (getEnvironmentInfo)] (def foo foo) (def bar bar) (def baz baz)). I fooled around with a couple of macros, but anything short of reimplementing destructuring in them would lead to a crippled result (I think :-) ).
08:58	cemerick	It's an infrequent pattern, of course, so it may not be worth thinking about too much.
09:01	rhickey	destructuring is available a la carte:
09:01	rhickey	user=> (destructure '[[a b] x])
09:01	rhickey	[vec__2149 x a (clojure/nth vec__2149 0 nil) b (clojure/nth vec__2149 1 nil)]
09:01	rhickey	user=> (destructure '[{:keys [a b]} x])
09:01	rhickey	[map__2150 x a (clojure/get map__2150 :a) b (clojure/get map__2150 :b)]
09:06	cemerick	Very nice.
09:06	cemerick	That's not in the docs anywhere, though -- I guess only defns that have docstrings make it in.
09:07	scgilardi	The ns-utils lib has a "vars" command that displays all the vars defined in a namespace. (vars clojure) is good to peruse from time to time.
09:09	rhickey	not doc'ed because I don't want to guarantee its interface yet, but it's stable, and obviously used often by Clojure
09:09	cemerick	rhickey: Sure, wasn't saying it should be doc'ed. Just happy I didn't pass over it.
09:09	rhickey	you could easily write a destructuring-def with it
09:10	rhickey	one trick about it is that it will return its argument if no destructuring was needed
09:11	cemerick	I might get around to it. The stuff that uses let for destructuring is put to bed at the moment.
09:12	cemerick	scgilardi: BTW, thanks very much for the lib tweaks (and pred as well...no need to keep carrying around our own similar utils anymore).
09:13	scgilardi	you're quite welcome. I'm glad you're finding them useful.
09:13	blackdog	scgilardi, where is this library?
09:14	blackdog	i don't see one by you in the Files section
09:14	scgilardi	http://clojure-contrib.svn.sourceforge.net/viewvc/clojure-contrib/
09:14	blackdog	ah, didn't know about that
09:14	blackdog	thx
09:15	cemerick	Yeah, it took me a minute to look in svn, too. :-)
09:15	scgilardi	clojure contrib has some cool stuff in it from a few folks :)
09:15	blackdog	neat, i thought everything of use was on the google group
09:16	rhickey	I'm hoping to fold some of the great stuff from contribs into Clojure soon after ECOOP next week
09:16	scgilardi	very cool. have a great trip. are you presenting anything?
09:18	rhickey	Yes, I'm presenting twice, once to the European Lisp Workshop on the Lisp nature of Clojure, and once at the Dynamic Languages Symposium on Clojure generally
09:19	rhickey	towards the end of incorporating contribs, I have been looking at adopting Sun's contributor agreement for Clojure: http://www.sun.com/software/opensource/contributor_agreement.jsp - any thoughts
09:19	rhickey	?
09:19	scgilardi	nice (re: presentations). I'll check out the website to see if they make videos or transcripts available.
09:24	rhickey	the main purpose of the SCA for Clojure would be to prevent it from becoming license-bound, i.e. everyone contributed under license X, preventing the project from moving to license Y, or X + Y. I like it because contributors give up none of their own rights
09:26	scgilardi	yes, it does seem like a light touch with the main goal of sharing the copyright on contributions. Sounds good to me.
09:54	Chouser	The SCA looks pretty good. I can't seem to find much meaningful critisizm of it, which is impressive for the kind of role it plays.
09:56	rhickey	It originally got bashed for not having the "Any contribution we
09:56	rhickey	make available under any license will also be made available under a suitable FSF (Free Software Foundation) or OSI (Open Source Initiative) approved license." language
10:01	Chouser	yep, I saw that, and it's a good clause to include.
11:10	cemerick	ffailla: Any news vis a vis Shoal on ikvm?
11:31	Lau_of_DK	Anybody up for tag-teaming on a quick 'n' dirty Clojure-IRC client ?
11:34	Chouser	ajax?
11:35	Lau_of_DK	swing?
11:36	Chouser	ncurses?
11:36	Lau_of_DK	Why not swing?
11:36	Chouser	:-) I guess my answer is "not really".
11:36	Lau_of_DK	oh
11:37	Lau_of_DK	Would have been fun to tag-team with the infamous CHOW-zarrrrrrr
11:37	Lau_of_DK	But I'll let you go
11:37	Chouser	heh.
11:37	Chouser	what do you mean by "tag-team" specifically?
11:38	Lau_of_DK	I'll fill you in a little later, dinners served. But I was thinking that we divide the tasks, quickly get something working, if somethings too difficult or not done well enough, clap each others hands and switchs jobs :)
11:40	Chouser	hm, interesting.
11:43	cemerick	sounds like the start of a clojurebot :-)
11:45	Chouser	hm, now that might be interesting.
11:58	cemerick	Am I right in thinking that currently the most idiomatic way of yielding a seq without an item is to filter?
12:11	Chouser	I guess it depends on how you know which item you don't want.
12:17	Chouser	(filter (complement #{:c}) [:a :b :c :d :e]) ==> (:a :b :d :e)
12:17	Chouser	(filter #(not= % :c) [:a :b :c :d :e])
12:18	Chouser	(for [i [:a :b :c :d :e] :when (not= i :c)] i)
12:19	Chouser	(disj (set [:a :b :c :d :e]) :c) ==> #{:b :d :e :a}
13:46	rhickey	(set/difference #{:a :b :c :d :e} #{:c})
13:50	Chouser	(reduce #(if (= %2 :c) %1 (conj %1 %2)) [] [:a :b :c :d :e])
13:52	Chouser	cemerick: so, do you have the value of the thing you want to remove, as all these examples assume? Or do you have its index?
13:53	cemerick	Chouser: sorry, disappeared for a bit. Yeah, I always have the thing I want to remove. I guess I'm thinking that a complement to conj would be handy.
13:54	rhickey	unj?
13:54	Chouser	ha!
13:54	rhickey	lists -> pop, set -> disj, map-> dissoc
13:55	rhickey	but remove from middle of list is not opposite of conj
13:55	Chouser	you might have duplicates in your seq, though, so you might want to be able to take from either end. like unj-early
13:55	Chouser	and unj-late
13:55	cemerick	True, true. Just talking into the wind, as usual. :-)
13:55	Chouser	cemerick: would your seq be better as a set?
13:56	cemerick	Unfortunately not.
13:56	Lau_of_DK	rhickey: Im considering doing a simple IRC client (swing) in Clojure - Have you got any insights to share _before_ I lay the foundation ?
13:57	cemerick	I already have a remove-one function that uses lazy cat to avoid consing up the rest of a seq after an item's been removed.
13:57	Lau_of_DK	Oh.
13:57	Lau_of_DK	:)
13:58	cemerick	I'm just always looking for the cleaner, more applicable solution. :-)
13:58	Lau_of_DK	Could you then tell me if there's any networking helpers thought into clojure, or if its going to be pure java interop ?
13:58	Chouser	cemerick: the file and for examples above are fully lazy
13:58	Chouser	er, "filter" and "for"
14:02	rhickey	Lau_of_DK: I would just grab a Java IRC lib and use it
14:03	Lau_of_DK	Okay
14:03	Lau_of_DK	I'll look into those - Have you checked out MigLayout rhickey ?
14:03	rhickey	no
14:04	Lau_of_DK	Its works very well with Clojure for making Swing applications, you can set up "complicated" GUIs with event handlers and everything in very few lines of code
14:04	pjb3	So as it turns out, there is an even better solution to Concurrency than Immutability, and that is to have no shared state
14:05	pjb3	This seem to me to be very common in J2EE web applications
14:05	Chouser	pjb3: with a relation database as the only shared data?
14:05	Chouser	relational
14:05	pjb3	You have Servlets, JSPs, access to a database via JDBC, and frameworks built on top of those
14:05	pjb3	Chouser: yeah, and the only shared data is in the database
14:06	pjb3	I bring this up to discuss the whole "State, you're doing it wrong thing"
14:06	pjb3	and I think a valid response to that is
14:06	pjb3	"No I'm not, I'm not sharing any data across threads"
14:07	pjb3	In other words, whether it be a J2EE app, or Ruby on Rails, or whatever, if you are building a web app that talks to a database, concurrency really isn't an issue, is it?
14:07	rhickey	Not doing state at all is perfectly fine - the tools are for when you need state
14:08	pjb3	rhickey: Sure, and the only reason I bring all this up
14:08	rhickey	pjb3: it is for the guys writing the appserver you're running on, or the database
14:08	pjb3	is that what I am finding, the more I work with Clojure
14:09	pjb3	the more I like it
14:09	pjb3	but it is for all sorts of other, non-concurrency related things
14:09	rhickey	I think one of the saddest things I see is when people pull data from a db and stick it in a mutable object
14:09	pjb3	and all these things should be mind-blowing to J2EE web app developers
14:10	pjb3	rhickey: so that's pretty common in web apps, what's sad about it
14:11	rhickey	why mutable? blows the functional/relational model
14:11	pjb3	not sure what you mean by functional/relational model
14:12	Chouser	I suspect that as web apps take more advantage of ajax and especially comet-like stuff, databases become less sufficient as the only state.
14:12	rhickey	the pervasive caching says that's already the case
14:13	rhickey	pjb3: you just touted the db as the only state, with a mutable object you've now got your state back
14:13	Chouser	imagine a chat server -- with polling, a db might be okay, but with comet you'd like to send a message across to another session. Suddenly you've got in-memory multithreaded state.
14:13	rhickey	db has state != app is single threaded
14:14	Chouser	rhickey: yes. did I imply otherwise?
14:14	rhickey	apps may need to leverage multiple cores to speed up any calculation
14:14	rhickey	Chouser: sorry, that was for pjb3
14:15	Chouser	ok
14:16	pjb3	rhickey: The mutable object is essentially a read-only copy, if you want the changes to persist, you call methods on the object to modify the data, and eventually the object generates a SQL update statement to put the new state of object into the db
14:16	Chouser	I hope to do some tests and performance tuning on the lazy xml stuff tonight. It seems to me that it ought to be nearly as fast worst case as xml.clj, and if you have multicores or can take advantage of laziness, significantly faster.
14:16	Chouser	rhickey: you can't just start the nick and press <tab>? what client?
14:17	rhickey	Chouser: thanks!
14:17	Chouser	:-) np.
14:17	pjb3	and AFACT, that's really no different that querying for data, storing it in an immutable map, creating a new, slightly different immutable map based on that, and then generating a SQL update to store that
14:17	rhickey	pjb3: it's way different
14:18	Chouser	surely if the mutable object is only within a single thread, it's only slightly different?
14:19	rhickey	It's way different because in one case you can add another thread without a rewrite, reuse the same logic in other MT apps, test without mocks and setup etc etc
14:20	rhickey	Chouser: the lazy xml is really neat, but the enqueue and esp. exceptions for flow control really bother me - is there no other way?
14:22	Chouser	I don't think there's any way around enqueue (or some other acts-like-mutable thread-local binding) without bringing in an new xml parser API (such as a pull parser). Even the existing xml.clj has a pile of thread-local bindings.
14:23	rhickey	Clojure was born in part due to the extreme pain I saw endured over and over when code that would 'only run with one thread' had MT added
14:23	Chouser	The exception is a little messy, but it's not really for flow control. It's only used to kill off an abandoned parser thread. Perhaps I could kill the thread some other way? Again, bringing in a pull parser would solve this.
14:23	pjb3	rhickey: web apps are MT, they just don't share state between threads
14:24	rhickey	maybe not today, but that is, IMO, a false presumption moving forward
14:26	rhickey	pjb3: and the easiest way not to share state is to not have it, e.g. use immutable data structures
14:29	rhickey	Chouser: I've been thinking a lot about seqs on stateful things, this queue thing is just another variant of the auto-closing stream requests
14:29	rhickey	same problem - dangling non-memory resource
14:34	drewr	Chouser: Is that double LET in your CASE macro a common idiom?
14:34	drewr	(With the GENSYM..)
14:35	Chouser	rhickey: that's a good point. your weak-ref solution might be the key.
14:35	Chouser	drewr: dunno.
14:36	rhickey	Chouser: I did a lot of testing and was frustrated by the unpredictability of weak-ref reclamation
14:37	Chouser	drewr: probably not uncommon though in a macro. the outer let is just for while the macro's expanding. The inner let is in the expanded code.
14:37	rhickey	sometimes threads came right back, other times they stayed around indefinitely
14:38	Chouser	rhickey: yeah, I was surprised to see at least one of those threads hang out for a few minutes with everything in the JVM idle.
14:38	Chouser	but that's the flip side of the ethereal GC you like so much, isn't it?
14:39	rhickey	Chouser: not really, we're trying to tie something non-memory to memory
14:40	rhickey	Chouser: and I think the problem is when it gets moved to another generation - real ephemeral memory doesn't get there
14:40	drewr	Chouser: Just seem strange to do in two LETs what I would think you wouldn't need to do at all. val already has a binding from the enclosing scope.
14:41	rhickey	Chouser: my latest thinking is possibly to have LazySeq implement Closeable, and lazy-cons take an optional third on-eos expression
14:41	Chouser	drewr: the inner let is common. I could have done without the outer let and just used val# if I hadn't done two separate `() exprs
14:44	Chouser	Hm, apparently doto in boot.clj uses the same idiom for essentially the same reason.
14:46	rhickey	Chouser: sure, nothing wrong with that - ` and blah# are convenience features with limits
14:48	Chouser	so what would call LazySeq's close method? Does Java do that automatically?
14:49	rhickey	Chouser: no, you'd use the with-open idiom
14:49	rhickey	plus auto-close on eos
14:50	rhickey	There isn't a way to let someone off the hook from knowing they're holding a resource
14:51	rhickey	could use dynamic var to free from manual registration: (closing-all ...)
14:52	Chouser	but you certainly don't want to have to use with-close on all seqs just in case they might have some special resource that needs closing.
14:52	rhickey	where resources would register with auto-close
14:53	rhickey	Chouser: no, but there's no free lunch either
14:53	Chouser	but you're so close with weakrefs! :-)
14:53	rhickey	finalization is a bad hook
14:54	Chouser	just as laziness can be passed up through a series of wrapped seqs, so would the need to use with-close.
14:55	rhickey	Chouser: I understand, but in the end what you are asking for is the messy stateful world to be as elegant as the beautiful lazy functional world, and it simply can't
14:57	pjb3	Are there docs on how to use clojure from within a java app?
14:57	Chouser	yeah, I guess the reason it hurts so much in my case is that the XML parser really doesn't need to be stateful, so I was nearly able to abstract away the statefulness. ...but not quite.
14:58	Chouser	or rather encapsulate it fully. but not quite...
15:00	rhickey	Chouser: the queue problem has a different formulation, where consuming from the queue fires off a one-shot agent request to put more in, but doesn't help your event-driven parser problem
15:02	Chouser	you're saying seque has the thread resource issue regardless of how the queue is filled? of course you're right.
15:04	pjb3	If I want to use clojure from within a servlet, what do I need to initialize Clojure?
15:04	pjb3	If I pass a String to clojure.lang.Compiler.eval, it throws a Null Pointer Exception
15:05	Chouser	eval wants a datastructure, not a string.
15:05	Chouser	but that's not the right direction anyway
15:05	Chouser	hang on, looking for a link...
15:05	rhickey	Chouser: no, the opposite, I think my original seque can be done with no hanging thread by sending after each take, rather than dedicating a filler...
15:05	pjb3	Chouser: thanks
15:06	rhickey	Chouser: but an event-driven SAX parser requires a dedicated thread and state
15:06	Chouser	pjb3: http://clojure-log.n01se.net/date/2008-06-28.html#10:44b
15:08	Chouser	rhickey: ah! yes of course! seque could send-off to get n ahead, and then send-off again once per consumer request.
15:08	rhickey	right
15:08	rhickey	each send would fill as much as possible then quit
15:09	Chouser	yeah, which would completely solve the resource issues with all seque's except for mine. :-)
15:09	rhickey	sorry :(
15:09	Chouser	stupid sax
15:11	Chouser	well, parallel.clj requires an external jar. I guess lazy-xml could require http://www.extreme.indiana.edu/xgws/xsoap/xpp/mxp1/index.html
15:11	rhickey	can you pause the sax parser in a handler?
15:12	Chouser	yes. I do that now by calling enqueque, which blocks.
15:12	rhickey	no, I mean tell the sax thingy to pause, and call resumeParse later
15:14	Chouser	I don't think so. I think the problem is that the sax parser's own state is just on the stack, and it sits there calling down into the handlers.
15:14	Chouser	it doesn't have a way to bundle it's state to resume later. Let me check the API again.
15:15	rhickey	ok. but even a pull parser will put you in the auto-close camp
15:17	Chouser	well, I guess I'll have a file or network reader at the bottom that might need to be closed, but I don't think the pull parser would add requirements above that.
15:17	rhickey	right
15:19	Chouser	but that's fine. the user of my parser api will give me the reader and will be responsible for closing it, just like they are now with xml.clj.
15:20	Chouser	each call to "rest" on my parser seq translates to a call to .next on the pull parser
15:20	rhickey	no doubt, a pull parser is a better fit
15:23	Chouser	I guess I could provide a clumsy solution with the built-in sax parser, but provide an identical api to allow switching to a pull parser.
15:23	Chouser	the former would have to do enqueue and all the rest, the latter could use whatever seque you settle on.
16:44	cemerick	pjb3: you were asking about an error starting the REPL in enclojure earlier...
16:44	cemerick	pjb3: There's a couple of patches on the enclojure google group that fix that (at least for me)
16:46	pjb3	cemerick: ok, I'll take a look at that, thanks
17:49	abrooks	rhickey: Chouser told me I should be participating in the above discussion.
17:50	abrooks	rhickey: I was going to bring up a related topic the other day when I was mentioning remote concurrency.
17:52	abrooks	I've been thinking about some sort of proxying object (or perhaps other mechanism -- a proxying object was a convenient way to think about this) which would allow lazy high-latency objects to work ahead a bit in a separate thread.
17:53	abrooks	The proxying object would be application and object type specific to suit different performance / overhead tradeoffs.
17:56	abrooks	The parser is a good example (I've not read all of the above yet...) but I've been picturing this sort of mechanism applying to any case where a lazy object incurrs high in-line latency penalties such as stream / file or remote object access.
17:57	abrooks	It would be nice to be able to take an object and tell it (not sure how -- special method?) to use function X to determine how far ahead to work. The default function would simply never work ahead.
17:59	abrooks	My appologies if the above is completely unclear -- my blood sugar crashed about 15 minutes ago and my head is spinning. Now I get to try to drive home through the rain like this... :)
17:59	abrooks	rhickey: I'll drop in here later to clarify and talk more about this.
18:05	pjb3	If I type gen-and-save-class at the REPL, I get an exception, unable to resolve symbol
18:10	rhickey	abrooks: have a look through yesterday's log - we were talking about seques, also: http://groups.google.com/group/clojure/browse_frm/thread/e7f4de566eddb6ea#
19:01	lisppaste8	pjb3 pasted "HelloWorldServlet" at http://paste.lisp.org/display/63177
19:02	pjb3	The above pastie generates the HelloWorldServlet class file, but when I run it in an app server, it doesn't appear that those methods get called
19:02	rhickey	pjb3: nice aquamacs screencast - thanks!
19:02	pjb3	oh, thanks, no problem
19:03	pjb3	init-void, that should override the public void init() method, right?
19:03	rhickey	yes
19:04	pjb3	hmmm...doesn't seem to work
19:04	rhickey	no errors loading servlet?
19:04	pjb3	no errors
19:05	pjb3	I can see the log message from the app server that it is initializing my HelloWorldServlet
19:05	rhickey	com.paulbarry.HelloWorldServlet.clj is in classes/com/paulbarry/ next to the .class file?
19:05	pjb3	oh, no it isn't
19:07	pjb3	unable to resolve gen-and-save-class
19:07	pjb3	that's progress
19:07	pjb3	I suppose I just need to make sure that gets loaded in HelloWorldServlet.clj
19:07	rhickey	you probably want the gen-and-save-class in a different file or in a comment, you don't want to run that when the servlet runs
19:07	pjb3	yeah, good point
19:08	rhickey	that's a one-time thing
19:09	jgrant	rhickey: rich, is there anything equivalent to sbcl's save-lisp-and-die function ?
19:09	jgrant	or some way to package everything up in a jar ?
19:09	rhickey	not if that does what I think it does
19:10	rhickey	Clojure does no ahead-of-time compilation at this point
19:10	rhickey	and serializing the state of Java is not going to happen
19:11	jgrant	yea i can see why
19:11	jgrant	serializing state is less important to me personally, i'm trying to figure out a way to package a clojure app as a jar
19:12	rhickey	other than jar?
19:12	jgrant	no
19:13	rhickey	with the .cljs and clojure.jar - user.clj should autoload, I guess what's missing is main?
19:13	jgrant	was just about to say that
19:34	jgrant	is it possible to read user.clj from another jar (say user.jar) instead of from the file system ?
19:35	rhickey	have you tried putting user.clj next to boot.clj in clojure.jar?
19:36	rhickey	user.clj will be found on the classpath
19:37	jgrant	that's what i gathered from read loadResourceScript
19:38	jgrant	Why would java -cp user.jar -jar clojure.jar not work ?
19:40	rhickey	http://forum.java.sun.com/thread.jspa?threadID=657160&messageID=3882114
19:47	jgrant	thx but using the -jar switch disables -cp (uggh)
19:47	jgrant	this works ...
19:47	jgrant	java -cp user.jar:clojure.jar clojure.lang.Script
19:49	jgrant	what's the idiomatic equivalent of common lisp's "collect" ?
19:51	rhickey	collect is a loop keyword - no loop in Clojure. you can reduce to build up results
20:05	jgrant	cool - this seems to do the trick ...
20:05	jgrant	(reduce (fn [x y] (conj x y)) '(0) '(1 2 3 4 5) )
20:06	jgrant	(i guess that's one possible definition of collect for clojure)
20:26	jgrant	is there an equivalent of the mod operator in clojure ?
20:26	pjb3	jgrant: you know you can write that as (reduce #(conj %1 %2) '(0) '(1 2 3 4 5) )
20:27	pjb3	(rem 5 2 )
20:27	jgrant	thx
20:27	jgrant	and yea
20:43	jgrant	rhickey : only one problem with this --> java -cp ../user.jar:../clojure.jar clojure.lang.Script -- hello
20:43	jgrant	command-line-args is nil
20:53	slava	rhickey: do you have a way of wrapping an Iterator in a seq?
20:55	rhickey	slava: yes, that happens automatically, iterators, enumerations, Iterables, strings, arrays and all Clojure collections support seq
20:57	Chouser	rhickey: you're not working on seque, right? I thought I might try to implement your ideas from today.
20:58	rhickey	go for it
20:58	slava	rhickey: sorry, i wasn't clear
20:58	slava	rhickey: i meant where in the source is it implemented (if it is, which it is)
20:59	meredydd	rhickey: If you wanted to make something that supported the (seq) operation, would the simplest thing just be to derive Iterator?
20:59	rhickey	slava: clojure.lang.RT.seq()
20:59	slava	cool thanks
20:59	rhickey	meredydd: the simplest way is to use lazy-cons
21:00	rhickey	meredydd: if you need a class, deriving from clojure.lang.ASeq is the best route
21:00	meredydd	rhickey: Ah, yes...but I'd like it to behave as something else until (seq) gets called on it
21:00	slava	a cool project for an aspiring hacker would be a clojure-like language that compiles natively using llvm.
21:01	meredydd	ASeq sounds promising. Thanks!
21:02	rhickey	slava: are there many libs for llvm?
21:03	slava	llvm is a codegen library
21:04	rhickey	slava: right, so you'd have next-to-nothing to build on?
21:05	slava	well, if all the libraries written in C count as "next-to-nothing", yes :)
21:09	rhickey	slava: it seems tediously low-level
21:10	slava	some people are interested in compiler implementation
21:12	slava	hotspot is not the last word in compilers, though
21:13	jgrant	right but the jvm was really designed/implemented in the beginning by people like Steele, Gabriel, Gosling etc.
21:13	rhickey	no, but it begs the question as to whether people should be working on per-language compilers or hotspots
21:14	jgrant	the highest volume sites on the web run on vms not in native code
21:14	slava	jgrant: the jvm compiles to native code so that's a moot point
21:14	jgrant	18:12 <slava> jgrant: the jvm compiles to native code so that's a moot point
21:14	slava	a better argument is that the highest volume sites on on languages with gc, which makes perfect sense to me
21:15	slava	nobody wants to manage memory mnually when they really want to be working on their web site
21:15	jgrant	yea yea everything 'compiles' to native code
21:15	slava	jgrant: not interpreters :)
21:15	rhickey	much more leverage from building a hotspot than an optimizing compiler for language X
21:15	jgrant	technically even interpreters do
21:15	slava	hotspot is an optimizing compiler for jvm bytecode
21:15	jgrant	just a matter of word games
21:15	slava	jgrant: not really
21:16	slava	there is a distinction between interpreting a sequence of instructions and generating code which performs the same operations
21:16	jgrant	translation/compilation aside interpreters/compilers still need to run some machine code
21:16	jgrant	yes yes
21:17	slava	a compiled program runs machine code generated by the compiler, an interpretd program runs the machine code of the interpreter itself
21:19	jgrant	either way the result is still machine code
21:19	jgrant	is it not ?
21:20	slava	of course in the end the cpu is running machine code, but the distinction between compilers and interpeters is a useful one anyway
21:20	jgrant	i for one would love it if my cpu understood english
21:20	rhickey	jgrant: no, the distinction matters - is the CPU executing the user's code or the interpreter writer's code
21:20	jgrant	yes it's useful no doubt
21:21	jgrant	the interpreters code is still modified by the script being interpreted to a large degree and influences the actual machine code being executed
21:21	jgrant	anyway
21:22	rhickey	jgrant: you're never going to satisfy compiler writers with that interpretation :)
21:23	jgrant	rhickey: you are right ! and I'm going to give up I swear :)
21:30	slava	personally i'm just interested in implementation and design of compilers
21:30	slava	if i wasn't, i'd be using hotspot, llvm, or compiling to c
21:31	rhickey	slava: fair enough
21:34	jgrant	slava : cool, i personally favor vms just because of the space i find myself working in mostly these days, i'm completely biased
22:30	Chouser	I am not truly interested in the implementation or design of compilers, so I'm happy to have rhickey. I just want to us a good language.
22:31	Chouser	s/to us/to use/
22:46	Chouser	rhickey: if the LBQ id not limited, the producer would now always do all the work to the end of the seq, even if the consumer loses all reference to it.
22:46	Chouser	vs. your latest seque that might notice vie the weakreference that it can give up before the end even with an unlimited LBQ.
23:04	rhickey	Chouser: if the LBQ is not limited, it will be because there aren't memory issues with fully loading it
23:04	Chouser	true, but if production is CPU intensive it can hog that resource.
23:05	Chouser	but I guess if that's a problem, you should limit your queue.
23:05	rhickey	just another reason to limit the LBQ - unlimited is ppretty risky
23:05	Chouser	good point
23:05	rhickey	right you are :)
23:06	Chouser	maybe unlimited shouldn't be the default
23:07	rhickey	I kept taking it out of mine...
23:09	rhickey	forget now why I put it back, I think it was just the 'I know this will fit, but not exactly how big it is' scenario
23:09	rhickey	gotta run
23:09	Chouser	if your producer is, say, network bound and you intend to end up with it all cached in a seq anyway...
23:09	Chouser	ok, see ya
23:24	Chouser	does anyone know if bopping in and out of try blocks is expensive?
23:27	Chouser	as in, is it much worse to put the try block inside a loop rather than outside?