#clojure – 2009-07-14

2009-07-14

00:47	yangsx	durka42: yes, that's my last-resort
03:10	Lau_of_DK	Good morning gents
04:55	svqyqb	http://tinyurl.com/nkypfa
04:56	jdz	,'(x ^ 2)
04:56	clojurebot	(x (clojure.core/meta 2))
04:57	jdz	this looks quite wrong to me
04:57	kotarak	Why?
04:57	jdz	oh, nvm
04:58	kotarak	^foo is syntactic sugar for (clojure.core/meta foo)
04:58	jdz	ye, i just checked the reader doc
08:05	mattrepl	anyone know if fixtures in clojure.test are supposed to work? 'run-tests doesn't seem to kick them off - i'll spend some time finding the problem but first wanted to verify it's not just me
08:06	mattrepl	in this specific case, I have a :once fixture... code here: http://github.com/mattrepl/clojure-cassandra/blob/c0b8acda065b312882a73755834c378f6aa0b2c4/src/cassandra/test.clj
08:40	Chouser	mattrepl: you're binding 'f' in the inner doseq.
08:40	Chouser	mattrepl: that shadows the 'f' arg, so you don't call what you want to call at (f)
08:42	mattrepl	Chouser: (f) is in outside the scope of that doseq though, no?
08:42	Chouser	oh
08:42	Chouser	yes. hm.
08:43	mattrepl	the problem I'm seeing is that init-db isn't invoked at all, so when the tests are run there is no database available
08:50	Chouser	mattrepl: you see your fixture if you eval ^(the-ns 'cassandra.test) ?
08:52	mattrepl	yup
08:55	mattrepl	though appreciated, don't worry about spending too much time on that specific case - just wanted to see if anyone else had issues with fixtures =)
08:56	Chouser	I've never heard of them before
08:56	Chouser	but it looks like if test-ns-hook is provided, the fixtures aren't called
09:00	mattrepl	ah, wondered about that. thought I tried it but guess the recompiled version with it commented out wasn't being picked up. easy to work around it, might submit a patch if the innards don't require too much modification
09:02	mattrepl	Chouser: it ok if I submit a ticket?
09:04	Chouser	heh. good question.
09:04	Chouser	that's not contrib anymore so I suppose we need rhickey approval for that?
09:05	mattrepl	it'll either be a quick fix, or a bigger reworking. but I think having fixtures and defined order of tests don't need to be mutually exclusive. though, it's not that hard to manually use the fixture by calling it in 'test-ns-hook
09:06	Chouser	my opinion is that a ticket is warranted -- it could be closed either with a fix to the code or to the docs, I suppose.
09:07	Chouser	rhickey: fixtures are a clojure.test feature
09:07	mattrepl	for clojure.test, fixtures aren't called if test-ns-hook is being used
09:07	mattrepl	test-ns-hook allows one to specify which tests get called (and their order)
09:08	Chouser	yeah, I hadn't heard of fixtures before. but they're in clojure now! :-)
09:09	Chouser	it's just a bit of combinatorial complexity. the test-ns-hook feature doesn't compose with the fixtures feature.
09:09	Chousuke	you suppose test-ns-hook could be replaced or augmented with a higher-level macro or something?
09:09	mattrepl	if you group tests under one big test (e.g., test-addition, test-multiplication are individual tests that could be called from a higher-level test, test-arithmetic) then to prevent the lower-level tests from being called directly the user needs to supply a test-ns-hook function that specifies which test to call
09:09	Chouser	test-ns-hook lets you control which tests in your ns get run and in which order
09:10	Chousuke	like (namespace-test-order [testfn1 testfn2 ...])
09:10	Chouser	but fixtures run something before and/or after each test
09:11	mattrepl	or before/after all tests
09:11	Chouser	right. the latter case would be easier to fix to work with test-ns-hook
09:12	Chousuke	while test-ns-hook could be the low-level "plumbing"... you could have ns-test-order generate (once-fixture (fn [] (each-fixture testfn1) (each-fixture testfn1) ...)))
09:12	Chousuke	and set it as the hook
09:12	Chouser	mmmmm... complexity. :-)
09:12	Chousuke	not really.
09:12	Chouser	anyway, the question at hand is: does something need to be fixed.
09:12	Chouser	"how?" can be answered later
09:13	Chouser	and I think at the very least the lack of support for the two features together should be documented.
09:13	mattrepl	I agree with you that at least documentation should be amended
09:13	rhickey	seems like something to discuss on the group. Too difficult to make decisions here not involving all interested parties
09:13	Chousuke	I don't think there's anything wrong with test-ns-hook; you could very well use it to set up a custom hook that ignores fixtures for a certain test.
09:14	Chouser	mattrepl: there you go -- you have recieved permission to bring it up on the group. :-)
09:15	mattrepl	heh, alright. Will fire a note off shortly
09:15	mattrepl	thanks for taking a look
09:16	Chouser	sure. thanks for pointing out a part of clojure proper that I didn't know existed! :-}
09:24	AWizzArd	rhickey: do you still have enough time to work "full time" on Clojure?
09:41	rhickey	AWizzArd: not a matter of time, but of money
10:42	rhickey	Has anyone tried the ensure branch?
10:43	rhickey	maybe I'll just have to merge it with master :)
10:43	drewr	I haven't yet.
10:43	Chouser	I don't even have any code that uses ensure
10:44	rhickey	Chouser: hopefully that code will be unaffected, but all STM code runs through new logic
10:44	Chouser	ah. well, not even very many transactions...
11:11	rys	Not having to sleep would be pretty excellent
11:13	rsynnott	rys: as long as employers weren't let in on the secret, yes
11:16	rys	Heh
11:16	rys	Being asked to work more hours on PHP projects would have to be close to the bottom of the programming ladder, yes
12:06	cemerick	wasn't there a function that returned the namespaced symbol for a var? It's easy enough to poke at the public fields of Var and Namespace, but I could have sworn that there was a fn for this. var-sym?
12:15	lisppaste8	cemerick pasted "Stuff like this makes me think I'm just doing it wrong..." at http://paste.lisp.org/display/83579
12:20	rhickey	cemerick: I don't think there is a fn for that
12:22	cemerick	rhickey: watching myself jump through hoops makes me think that wanting that symbol is indicative of a more fundamental design flaw (on my part)
12:23	rhickey	could be
12:23	rhickey	vars aren't necessarily interned
12:24	rhickey	or there hasn't been much demand. Vars used to keep their syms ns-qualified
12:25	rhickey	ggroups seems to have stopped updating membership counts
12:26	rhickey	2212 vs 2028
12:30	cemerick	I need to track whether certain functions have been applied to certain objects, so I've been keeping a map of fns -> sets of objs around. That gets a little tiring when debugging, so I figured I'd keep a map of symbols of fns -> sets of objs. Seems simple enough, but I feel like I'm going to get burned.
12:44	rgr	quit
12:57	AWizzArd	rhickey: and I was already wondering why nothing happens anymore
12:57	AWizzArd	typically the user count went up a little every few days
12:59	cemerick	is user count really a concern in general?
12:59	rhickey	its still going up, they must not be running the map-reduce job that updates the front page stats
13:53	Chouser	cemerick: seems like I've written a function like that before.
13:55	Chouser	Hm. I want 'promise', but we're on 1.0.0 and it would be tough getting our build system to use git instead of fetching a .zip
14:01	technomancy	so is it true that keywords can't have metadata?
14:02	Chouser	,(instance? clojure.lang.IMeta :foo)
14:02	clojurebot	false
14:02	technomancy	=(
14:02	technomancy	I guess I can use symbols for this
14:02	Chouser	there's only one keyword object for each keyword
14:03	Chouser	so you wouldn't be able to have two :foo's with different metadata
14:03	technomancy	right, that makes sense
14:03	technomancy	but that would be true for symbols too, right?
14:03	Chouser	nope, lots of symbols that look the same.
14:03	Chouser	,(identical? 'a 'a)
14:03	clojurebot	false
14:04	technomancy	wouldja look at that
14:09	Chouser	,(binding [print-meta true] (prn '{:a #^a foo, :b #^b foo}))
14:09	clojurebot	{:a #^a foo, :b #^b foo}
14:10	Chouser	,(binding [print-meta true] (prn '#{#^a foo, #^b foo}))
14:10	clojurebot	#{#^a foo}
14:18	Anniepoo	anybody know where to tell La Clojure/IntelliJ innerds where clojure is? Have a working project, made a new one, and askign for a repl does java.lang.NoClassDefFoundError: clojure/lang/Repl
14:20	Anniepoo	strange part is, I can compile and run
14:22	Anniepoo	(fwiw, this is a bug in La Clojure)
15:07	Lau_of_DK	Where do I go to read about these upcoming modifications to the STM ?
15:08	Chouser	which ones?
15:09	hiredman	I've heard of exposure of some already existing nobs, but not modifications
15:09	Lau_of_DK	Chouser: Ensure branch, etc
15:09	Chouser	oh! I've not seen anything detailed about the ensure branch. I guess there was a g.group thread that may have had the gist of it.
15:11	Chouser	Lau_of_DK: http://groups.google.com/group/clojure/browse_thread/thread/f7b4365b1c71b665
15:11	hiredman	I seem to recall that currently ensure just does a dummy write or something, so I imagine the ensure branch is about actually implementing ensure as its own code path
15:11	Lau_of_DK	Thanks
15:34	rzoom	after reading that thread about ensure, it is amazing that clojure does all of that "under-the-hood". wow.
15:39	rhickey	hiredman: ensure never did a dummy write, but took a similar write lock, now takes shared read locks. Thus, ensure now sits squarely between reads and writes, imposing no conflict with reads but holding up writes. It should be avoided unless you have a genuine write-skew situation, rare in practice
15:39	rhickey	http://en.wikipedia.org/wiki/Snapshot_isolation
15:39	hiredman	I see
15:40	rhickey	the benefit is now multiple overlapping ensures all succeed
15:40	rhickey	before they took turns
15:40	hiredman	ah
15:41	rhickey	vs dummy writes, which will (still) take turns
15:46	Chouser	sigh
15:47	rhickey	I'm closer to adding map! or mapv all the time - would it help?
15:47	Chouser	yup
15:48	Chouser	(map deref (doall (map make-promise-fn input-seq)))
15:49	Chouser	if input-seq were longer, I suppose inserting a seque might make sense as well.
15:49	Chouser	hm
15:49	Chouser	actually...
15:49	rhickey	(mapv (comp deref make-promise-fn) input-seq))?
15:50	Chouser	well, I want the make-promise-fn calls to run on ahead
15:51	rhickey	I was ignoring that bit
15:51	Chouser	oh
15:51	Chouser	well then, yes
15:51	Chouser	:-)
15:51	rhickey	what about mapv as the 'imperative' map
15:51	rhickey	would return a vector
15:52	rhickey	non-lazy
15:52	Chouser	essentially like (vec (map func coll)), but implemented more efficiently?
15:52	rhickey	right
15:53	Chouser	works find for me. I find myself wanting (vec (for ...)) approximately as often
15:53	rhickey	and (vec (filter .. etc
15:53	Chouser	actually -- I dunno.
15:53	Chouser	yeah
15:54	Chouser	maybe better to have vec standing out there, telling everying you're going non-lazy here
15:54	Chouser	in this case it was just a silly slip do you dorun instead of doall -- I use both infrequently and get them confused.
15:54	Chouser	should have just used vec
15:55	rhickey	vec is the advice I give these days
15:55	Chouser	s/should have/could have/
15:55	Knekk	(vec forces evaluation?
15:55	rhickey	Knekk: has to
15:55	Chouser	only didn't becuase it seemed silly to go do a vec in the middle of (map ... (map ...))
15:56	Knekk	rhickey: It's not documented, for those of us who don't yet start thinking about how data is implemented in clojure
15:57	rhickey	Knekk: only lazy things are documented as such, everything else is not lazy
15:58	rhickey	#!(map ...)
15:59	rhickey	#!(for...) #!(filter ..)
15:59	Chouser	is that vec or doall ?
15:59	rhickey	vec
15:59	Chouser	ok
16:00	rhickey	one problem is it no longer returns a seq
16:00	clojurebot	People have a problem and think "Hey! I'll use a regular expression!". Now they have two problems....
16:00	rhickey	clojurebot, the life of the party!
16:01	hiredman	~rhickey
16:01	clojurebot	he works hard so you don't have to
16:03	Lau_of_DK	hehe, fun
16:09	Chouser	huh, this works: (def #^Integer nums {:a 5})
16:10	Chouser	as in, this then requires no runtime reflection: (.shortValue (nums :a))
16:13	hiredman	Huh
16:14	Chouser	of course if you use (get nums :a) you lose it
16:14	hiredman	weird
16:14	hiredman	I don't understand that
16:14	technomancy	that's wild
16:15	hiredman	it seems like that should make type hinting the return values of functions possible
16:15	Chouser	it does
16:16	hiredman	(defn #^{:tag Integer} foo [a b] (+ a b))
16:16	Chouser	the :tag metadata on a var means either that var holds a value of that type or holds a function that returns that type
16:17	hiredman	no kidding
16:17	hiredman	of this I was not aware
16:17	Chouser	your foo example works fine
16:18	hiredman	I, of course, was jsut playing with it in a repl
16:18	Chouser	or just (defn #^Integer foo [a b] (+ a b))
16:18	hiredman	I started looking at rewriting LispReader in clojure
16:19	Chouser	ah! what do you think?
16:19	hiredman	read() is very imperative
16:19	hiredman	and many things are private or package scoped
16:20	ozzilee	Mind-bender: If Foo is a gen-class class, and it uses bar.clj, can functions in bar.clj call methods from Foo's superclass?
16:21	ozzilee	Wait, I'm doing something terribly wrong.
16:23	ozzilee	Ok, Foo inherits from javax.servlet.http.HttpServlet. It's compiled into a .war file. I want to call Foo's inherit getServletContext method. It's not a static method. How can I get at the Foo instance?
16:23	hiredman	I wanted to start by just implementin LispReader/read and still calling stuff in LispReader and slowing swap stuff out
16:25	replaca__	rhickey: are you hanging out in these parts?
16:25	Chouser	Anyway, there's currently no way to hint (defn nums {:a 1}) so that you can do (.count nums) and (.shortValue (nums :a)) without runtime reflection
16:26	Chouser	hiredman: ah. yeah, you might have to go whole-hog
16:26	hiredman	:(
16:26	hiredman	anyway, I am going to continue to meditate on it
16:30	ozzilee	This is insane. Surely someone has gotten Compojure to serve resources out of a .war file?
16:31	Chouser	ozzilee: you want to call an inherited method of a gen-class class?
16:31	Chouser	ozzilee: see :exposes-methods in (doc gen-class)
16:32	Chouser	I didn't say that right. See that doc anyway. :-)
16:34	ozzilee	Chouser: I don't know if that helps me. I need to call an instance method, but I don't see a way to get hold of the instance.
16:35	Chouser	you're in a gen-class namespace?
16:35	Chouser	that is, where is the code that's trying to make the call?
16:35	ozzilee	Chouser: In a file :use'd into a gen-class namespace.
16:36	ozzilee	In the namespace I'd be able to do it. I think I need to get the instance through some other means though.
16:36	Chouser	who is calling your :use'd code?
16:38	ozzilee	Hrm. Me, directly, on the repl, without the class ever being instantiated. I was thinking it was a static method, it's not. Can't be done this way.
16:40	ozzilee	I have some initialization code I need to run when the webapp is deployed, I was going to just run it with a repl with the .war file, but it doesn't work because I can't get at resources without a servletconfig. I'll have make a separate initialization tool.
16:40	ozzilee	Or make the initialization code callable through the webapp.
19:15	hamza`	are there any side effects to creating a structure called a line and use a varible name line to refer to the line structure?
19:15	ataggart	the variable name wilol shadow the struct so you won't be able to call (struct line)
19:15	ataggart	but other than that I don't htink so
19:16	Raynes	That's odd. Why would he ever need to?
19:17	hamza	sorry i got disconnected can you write what you said again..
19:18	Raynes	[18:14] <ataggart> the variable name wilol shadow the struct so you won't be able to call (struct line)
19:18	Raynes	[18:14] <ataggart> but other than that I don't htink so
19:18	ataggart	typos and all :)
19:18	Raynes	ataggart: :p I only copy things, I don't fix them. :)
19:19	hamza	thank you.
19:21	hiredman	“which makes sense since 5 could be anything”
19:27	Raynes	"I tried Clojure now, "Hello, World" takes over 1 second to start and run for me. Is it supposed to be like that, or am I doing something wrong?"
19:27	Raynes	What is wrong with people? :\|
19:28	Chousuke	:P
19:28	Raynes	They always seem to forget that Clojure is running on the JVM.
19:28	Chousuke	well, it is a real problem.
19:28	Raynes	Indeed, but still.
19:28	ataggart	there are no solutions, only trade-offs
21:20	cp2	ffsdafsdfds231233346123123332131234444
21:20	cp2	oops
22:02	cark	hello
23:21	grrrt	If I were to package a project and put it online somewhere, what's the best way to deal with dependencies?
23:21	grrrt	I currently have clojure, clojure.contrib, jLine and a jar for Swank/Clojure support in my lib dir
23:22	grrrt	but including them in the project might not be such a good idea
23:22	grrrt	- this is for development only, a finished product would be self-contained
23:30	technomancy	grrrt: if your project doesn't have any non-development dependencies outside clojure or contrib, just offering it as a jar is reasonable
23:30	technomancy	grrrt: is it an application, or a library?
23:31	grrrt	it wil be a library
23:31	grrrt	it's about the packaging of the source code
23:31	grrrt	in a repository somewhere
23:31	technomancy	in that case it would be most useful for others using it as a dependency to make it a maven project
23:31	technomancy	since that's the only system that supports real dependencies
23:31	grrrt	yeah I know...
23:31	grrrt	so clojure's in maven now
23:32	grrrt	but what about clojure.contrib?
23:32	technomancy	it's not in the central repos, but there are 3rd-party repos that have it
23:32	grrrt	ah that's good to know. I'll search the google group for info
23:32	technomancy	actually... you might be able to use corkscrew for this
23:32	clojurebot	corkscrew is a proof-of-concept build system and dependency manager (http://github.com/technomancy/corkscrew)
23:33	grrrt	hmm
23:33	grrrt	interesting!
23:33	technomancy	just put a project.clj file in your project root that mentions the contrib dependency, then run "corkscrew install"
23:33	technomancy	then your ~/.m2/repository directory should be good to go; you can rsync it to an HTTP server somewhere and anyone can use it as a dependency
23:33	grrrt	I'll look into that, thanks
23:34	technomancy	I would like to get corkscrew to a point where it works with zero maven knowledge, but at this point the abstraction will probably leak out a bit
23:34	ddonnell	how do I build clojure-contrib?
23:34	technomancy	grrrt: I'm about to head off, but you should be able to catch me here later this week if you have questions.
23:34	grrrt	thanks!
23:35	grrrt	I'll look at corkscrew
23:35	grrrt	and try to get my library sources presentable :)
23:35	technomancy	well that's the hard part. =)
23:35	technomancy	what's the library?
23:35	grrrt	hm
23:36	grrrt	I had to think about that for a second :)
23:36	grrrt	there are three parts: a system to create Swing widgets in a very simple declarative fashion
23:36	technomancy	actually just putting your library in a public git repo and keeping all the source under src/ is enough for it to work as a dependency using corkscrew, but since there are only about five corkscrew users in the world (including you) that's not so great. =)
23:36	grrrt	a system to make Swing's listener and event system behave better / easier with clojure
23:37	grrrt	and, the main dish: a dataflow approach to getting values and events from one place to another
23:37	technomancy	cool
23:37	grrrt	well I have to make it work first :)
23:37	grrrt	still a proof of concept. but I might be onto something
23:37	technomancy	at least half of all clojure projects in existence are proofs of concepts.
23:37	grrrt	haha
23:37	grrrt	true
23:38	grrrt	the idea of my approach is that you create signals from some source (a swing widget, a ref, ...)
23:38	grrrt	to some target
23:38	grrrt	the system defines operations on signal flows, such as filter, map, merge and split
23:39	grrrt	at least in theory it does :)