#clojure – 2008-09-24

2008-09-24

00:48	arohner	can you create a macro that takes a variable number of arguments?
00:48	arohner	I'm trying to use the same syntax as defn, but it's not quite working out
00:49	lisppaste8	arohner pasted "macro" at http://paste.lisp.org/display/67353
01:07	arohner	nm, got it working
10:47	Chouser	anyone want to help me churn out another few hundred lines of tedious JavaScript?
10:47	tomhickey	Chouser: how tedious?
10:48	Chouser	I'm walking through clojure/lang/*.java and translating to JS.
10:50	Chouser	Not all of it will have to be done: nothing from Compiler.java, for example.
10:50	tomhickey	Chouser: i would need to take some time to review what you've done so far, but i'm interested in getting involved with the clojurescript work
10:50	Chouser	clj.js is the file I'm populating now. I think nearly everything else is done.
10:51	blackdog	is that up to date on contrib Chouser ?
10:51	Chouser	I already did the fun part, writing Clojure code that translates ClojureScript to JavaScript.
10:52	Chouser	blackdog: yep, close enough. I'm working on PersistentHashMap now, and none of that is checked in.
10:53	blackdog	i'll have a look too, it would be nice for me to be able to do all my stuff in clojure, basically servlets right now, but adding a clojure client would be cool
10:54	Chouser	I'm not sure how big this "runtime" piece will be in the end -- that is, how much JS you'll have to load into your page for ClojureScript to work.
10:55	Chouser	I also don't know how fast we may be able to make it.
10:55	Chouser	either of those could make using it a "deal breaker" in a lot of cases, I'm afraid. We'll just have to see how it goes.
10:57	Chouser	blackdog, tomhickey: thanks for even considering helping. :-)
10:58	Chouser	I'm also completely open to critique of my approach. Anything you can think of to make the JS smaller, faster, or easier to write would be great.
10:59	Chouser	For now I'm mainly working on getting something working correctly, and trying to mimic the layout of the .java closely enough that patches there can be pretty easily ported over to the Js.
10:59	blackdog	i think an important thing if possible is how well the integration with standard js libs is, well like jquery for example
11:00	blackdog	not just doing a clojure port, but making sure those popular frameworks can be dealt with
11:00	blackdog	dojo, ext etc
11:00	blackdog	and also debugging, but i guess that is really tricky
11:00	Chouser	one of the benefits of JS over Java is that it's already dynamic. This allows more seamless integration between the two.
11:01	Chouser	For example, if you make a cljs function named foo in a namespace my.ns, you can call it from JavaScript just by saying: my.ns.foo( a, b, c )
11:02	Chouser	interop the other way looks just like in clojure: (.getElementsByTagName document "script")
11:02	blackdog	ok, and calling into a js namespace is ?
11:04	blackdog	ok so call into jquery would be (.css JQuery "div" "bakground-color" "#0") for example
11:05	blackdog	so the top level global is the object
11:05	Chouser	hm, good question. We may need a bit more tweaking there -- I think we'd want it to be (JQuery/css ...) and I don't think that works right now.
11:06	blackdog	i'm not sure if that's a static or not
11:06	blackdog	i think in practive JQuery("#id") actually adds to the object itself
11:07	Chouser	It looks like your example works as-is. We should have to ability to make other forms work as needed.
11:07	blackdog	but the good thing is it's all so dynamic it can be dealt with
11:08	Chouser	Right, and rhickey supports this effort, so if we need to get patches into Clojure, that's definitely an option.
11:09	blackdog	i have to say i think this is a very important effort, i was drawn to the haxe programmign language originally because it supports multiple "platform" options
11:09	blackdog	js is one of those
11:09	blackdog	but it's server side story is weak
11:09	blackdog	this is coming from the other direction
11:09	Chouser	yep, I found exactly the same thing with haxe.
11:10	Chouser	It would be interesting to add a Flash target to clojure as well.
11:11	blackdog	if you used haxe, i tried to implement a jquery lib on top of it, hxServlet
11:11	blackdog	oops wrong lib, hxScriptlet
11:12	blackdog	so i can see the benefits of targetting js
11:12	blackdog	esp with these massive speed increases
11:12	baetis-fly	hi folks. new to closure here, hope this isn't too silly: is there something similar to common lisps subst that i can do on a seq or should i just write my own. and if i find myself writing my own does that mean i'm doing something fundamentally flawed :)
11:13	baetis-fly	subst in common lisp replaces the nth value with something else.
11:13	Chouser	baetis-fly: clojure vectors support that directly.
11:13	Chouser	baetis-fly: do you specifically want something that works on any kind of seq?
11:14	Chouser	blackdog: yeah, the JS speed increases we're seeing make something like this less ... ridiculous. :-)
11:14	baetis-fly	Chouser: well, i was kind of under the impression that i should try to make everything work ok seq, but i guess using a vector would solve all my problems.
11:14	blackdog	:) did you see squirrelfish are posting 2 * v8 now too
11:14	blackdog	it's already in their trunnk apparently
11:14	blackdog	amazing
11:15	baetis-fly	Chouser: i'll just try to get my function to work on a vector as a starting point and maybe revisit it with seq later. Many thanks.
11:17	Chouser	blackdog: no, I hadn't seen that. Well, I don't care whether squirrelfish, V8, or tracemonkey wins, as long as they keep egging each other on.
11:18	blackdog	yep all to the common good
11:19	Chouser	baetis-fly: PersistentVector's internal design is specifically made to make setting a particular index fast. You could write something that works on any given lazy seq, but there's no way it could be as efficient.
11:19	blackdog	http://webkit.org/blog/214/introducing-squirrelfish-extreme/
11:21	Chouser	I hope writing the persistent collections in JS is the right choice. I made a brief attempt at writing them in Clojure, but it didn't look like it was going to work very well.
11:22	Chouser	But if that could be made to work, cranking out a new target (Flash, C#, Java source code, etc.) would be smaller task.
11:22	blackdog	well it fits more clojure's model right now, which may help the port
11:23	Chouser	hm, scratch Java source from that list -- Java's already got the collections. ;-)
11:23	blackdog	like haxe has a common set of haxe libs which are #if according to platform
11:23	blackdog	and makes a port easier
11:26	blackdog	probably the base ds need to be native for performance though, maybe get better optimisation
11:27	blackdog	it was interesting that your closure test was a lot slower than the prototype test
11:27	Chouser	yes, I was surprised at how different.
11:27	blackdog	and it seems that webkit is using the same optimisation technique as v8 too, creating background classes
11:28	Chouser	Now that I'm further into the project, I'm much less worried about the lack of protection.
11:29	Chouser	People just aren't going to use this code from JS -- they'll use cljs, and that won't expose the dangerous parts in any natural way
11:30	baetis-fly	http://paste.lisp.org/display/67372
11:31	baetis-fly	is that remotely correct for a shuffle in clojure? I realize it doesn't return the vector (getting there :)
11:32	Chouser	baetis-fly: (doc rand-int)
11:34	Chouser	I think there have been discussions of other shuffle algorithms on the google group, but for this algorithm your implementation's not bad I think.
11:35	baetis-fly	yeah, it was just an excercise. i don't actually need to shuffle anything.
11:35	lisppaste8	ozzilee pasted "Java Shuffle" at http://paste.lisp.org/display/67373
11:35	ozzilee	There's another way :-)
11:37	baetis-fly	ozzilee: bah, that's cheating ;)
11:37	blackdog	ozzilee, that was my approach too :)
11:38	Chouser	baetis-fly: you might use (doseq n (range (count v)) ...) instead of loop/recur
11:39	Chouser	hm, scratch that -- you'd have to use reduce or something to pass along your incrementally modified vector.
11:39	baetis-fly	the java version is faster :(
11:39	baetis-fly	as in ozzilee's version.
11:40	Chouser	baetis-fly: http://groups.google.com/group/clojure/browse_thread/thread/180842eb58c58370
11:41	baetis-fly	Chouser: oh great. thanks for that. Note to self: search the google group.
11:56	Chouser	rhickey: good morning!
12:02	rhickey	hey - broadcasting live from the JVM languages summit!
12:02	blackdog	oh nice
12:02	blackdog	where?
12:04	rhickey	Sun Santa Clara
12:04	blackdog	nah, the live feed :)
12:04	blackdog	don't see it
12:04	blackdog	on the summit page
12:04	rhickey	this is it
12:05	blackdog	you!
12:05	blackdog	ok
12:05	blackdog	gotcha
12:11	fyuryu	it seems the summit will be recorded by InfoQ
13:09	Chouser	clj.js is already up past 1200 lines, and it's got a ways to go. :-/
13:12	shoover	Chouser: Yeah, that may be a bummer, but keep your eye on the prize... once it's done you're writing Clojure!
13:13	Chouser	heh, yeah.
13:13	Chouser	Hopefully this will all compress down to some sane size.
13:25	baetis-fly	ok, another questions. I can call (seq (myfunc (range 10)) just fine, but if i make my func call (seq result) i get a class cast exception on Range. What's the difference?
13:26	baetis-fly	where my func converts it's argument to a vector at the start, but wants to return it as a seq.
13:26	baetis-fly	i can paste if it's not clear.
13:27	Chouser	baetis-fly: I think you'll have to paste. Sounds like it should work.
13:29	baetis-fly	http://paste.lisp.org/display/67381
13:31	baetis-fly	same problem if i (seq (loop
13:35	fyuryu	baetis-fly: i think you're hiding seq
13:35	fyuryu	your parameter is named seq
13:35	baetis-fly	ug, of course.
13:36	baetis-fly	fyuryu: that was it. many thanks.
13:36	fyuryu	baetis-fly: np
13:38	Chouser	fyuryu: good catch. I was stumped.
13:40	achim_p_	hey
13:40	achim_p_	Chouser: i just discovered your zip-filter.xml lib. very nice!
13:40	achim_p_	i was just about to get started on something similar when i found it. saved me a lot of time, thank you!
13:41	achim_p_	(half-finished rewrites of stuff i didn't know already existed - i'm rather good at these ;)
13:45	Chouser	achim_p_: glad you like it.
13:45	Chouser	as far as I know, it's not gotten a whole lot of abuse yet, so I'd be interested to know how it works out for you.
14:01	achim_p_	Chouser: doing very basic stuff (for now): extracting dependency information from maven metadata (e.g. getting every dependency with runtime scope from a file like http://repo1.maven.org/maven2/maven/maven/1.1/maven-1.1.pom). so there's not much to report, but i'll let you know if i run into troubles
14:02	achim_p_	i like the way the query expressions seem to resemble xpath
14:03	Chouser	that was a specific goal.
14:03	Chouser	I like xpath. :-)
14:04	Chouser	the other main goal, though, is to allow you to drop in custom filter expressions, which isn't natural in any xpath API I've seen.
14:34	achim_p_	Chouser: yes, i've seen it's possible, but haven't used it yet. it's a nice feature
14:35	achim_p_	btw, speaking of reimplementing already existing things: i'm (ab)using maven repos. metadata to implement some kind of "add-classpath" replacement for jars on the net, with local caching and automatic dependency resolution.
14:35	achim_p_	you could start your code with e.g. "(deps/depend :maven [["org.apache.velocity" "velocity" "1.6"]])" and the specified jars plus dependencies would be downloaded into a local directory (in case they weren't in there already) and added to the cp. has this or sth similar been done? would this be useful to anybody?
14:40	achim_p_	PLT does vaguely similar things with planet
14:41	Chouser	I think people have discussed similar schemes in general, but I've not heard of anyone working on an implementation.
14:47	ozzilee	achim_p_: That would be killer. Even without the automatic downloading, some kind of local shared repository of jars would be great.
14:49	achim_p_	ok, i'll tinker on then ...
16:00	Chouser	gah. Anyone know of some good fast hashCode code for JS?
16:20	baetis-fly	\quit
16:43	Chouser	ns :use ?
16:44	drewr	No, the function use.
16:44	drewr	I would say USE, but rhickey doesn't like that. :-)
16:44	Chouser	what are you trying to do?
16:44	drewr	If I say (use 'dbauth), I get all the symbols in the dbauth namespace grandfathered into my current one.
16:45	Chouser	yes
16:45	drewr	But then if I say (require 'dbauth), it doesn't get the dbauth ns.
16:46	drewr	Sorry, if I do (use 'dbauth :require), it doesn't mimic (require 'dbauth).
16:46	Chouser	ah
16:47	Chouser	what would you want it to do?
16:47	drewr	Something different than just (use 'dbauth) :-)
16:47	Chouser	Use "use" when you might otherwise do both "require" and "refer"
16:48	drewr	Hm, OK.
16:50	Chouser	If you really want to use "use" but don't want it to bring in any symbols, you could say (use '[dbauth :only []])
16:51	drewr	I was just trying to migrate to use usage.
16:51	drewr	If I still need require, I can use it too.
16:53	Chouser	I think ns is recommeneded now above both use and require. (ns my-ns (:require dbauth))
16:54	drewr	Oh.
17:49	aperotte	hello everyone
17:53	drewr	aperotte: Hi.
17:53	aperotte	hi drewr
17:53	aperotte	I'm new to clojure
17:54	aperotte	but very excited about it
17:54	aperotte	how are you?
17:57	drewr	Doing fine, thanks.
17:57	drewr	We're all excited about Clojure!
18:02	aperotte	Since I'm relatively new to thinking about building things using functional programming and concurrency, I wanted to ask for a more well informed opinion
18:04	aperotte	In general, I was curious about whether clojure would be a good choice for machine learning sorts of problems
18:05	aperotte	things that you would usually write to include lots of elements, each of which change with time
18:11	fyuryu`	aperotte: that kind of problems often involve lots of number crunching
18:13	fyuryu`	aperotte: so it's probable that you'll have to write some java
18:14	fyuryu`	because Clojure uses boxed numbers, which are slow
18:14	aperotte	oh ok
18:14	blackdog	you can type hint numbers
18:14	blackdog	and they can be very fast
18:14	fyuryu`	but if you're prototyping clojure is perfect
18:14	fyuryu`	you can optimize better
18:15	fyuryu`	s/better/later
18:15	blackdog	http://clojure.org/java_interop
18:15	blackdog	have a look at java primitives
18:16	blackdog	close to the bottom
18:16	fyuryu`	blackdog: yeah that too
18:16	aperotte	yup, I'm there
18:16	aperotte	oh ok ... that's fantastic
18:17	fyuryu`	blackdog: but it's mostly for arrays, right?
18:17	blackdog	not sure haven't used it
18:18	fyuryu`	blackdog: because most of the good stuff comes via seqs
18:19	aperotte	are the java primitives mutable?
18:19	aperotte	and would I need to use mutation to get decent performance?
18:20	blackdog	you can use set! if you have a thread local variable
18:20	blackdog	i think
18:20	blackdog	Chouser would have the definitive answer
18:20	aperotte	ok
18:20	fyuryu`	aperotte: primitives are not mutable, but you're probably asking for something else
18:21	fyuryu`	java objects are (if they have mutable members)
18:21	aperotte	I mean if I make an array of java primitive floats, can I then assign to one of the members
18:22	fyuryu`	aperotte: yes
18:24	aperotte	thanks fyuryu` and blackdog
18:24	blackdog	yw
20:20	wmorgan	http://paste.lisp.org/display/67399 <-- I'm struggling with nested macro-quotes. Any ideas?
20:51	shoover	wmorgan: what if you replace the nested backquote with (list default x#)
20:53	wmorgan	won't work because then x# doesn't get gensym'd at all
20:56	Chouser	you can't use the x# syntax in nested backticks -- they only resolve to the same symbol within the same level of backtick
20:57	Chouser	oh, you figured that out already. :-)
20:58	wmorgan	yeah, and I added an annotation with one solution that I don't really like
21:02	shoover	given the limitation, maybe you just need to make your own (let [x (gensym)] ...)
21:07	shoover	does this do what you want? http://paste.lisp.org/display/67399#2
21:08	wmorgan	shoover: that's exactly right, thanks
21:12	shoover	no problem