#clojure – 2010-08-07

2010-08-07

03:14	neotyk	,(doseq [{a :a b :b :or {:a 1 :b 2}} #{{:a 3} {:b 4}}] (println a " " b))
03:14	clojurebot	nil 4 3 nil
03:14	neotyk	how do I get 1 4 3 2?
03:20	hiredman	you don't use keywords in the :or
03:20	hiredman	,(doseq [{a :a b :b :or {a 1 b 2}} #{{:a 3} {:b 4}}] (println a " " b))
03:20	clojurebot	1 4 3 2
03:33	neotyk	hiredman: thank you
05:56	tomoj	any good blog articles about zippers?
07:34	defn	(doc dorun)
07:34	clojurebot	"([coll] [n coll]); When lazy sequences are produced via functions that have side effects, any effects other than those needed to produce the first element in the seq do not occur until the seq is consumed. dorun can be used to force any effects. Walks through the successive nexts of the seq, does not retain the head and returns nil."
10:17	Bahman	Hi all!
10:25	raek	good morning, Bahman (SGT)
10:26	Bahman	Hi there raek!
10:26	Bahman	What's SGT?
10:26	raek	standard greeting time
10:26	raek	user joins => morning, user about to leave => night
10:26	Bahman	:-)
10:26	Bahman	In fact, I'm joining at evening after work.
10:26	Bahman	:-D
10:27	raek	yes, local time and greeting time can be very different :-)
10:29	Bahman	LOL Subtle explanation!
10:42	gfrlog	why can't I "use" a namespace created in the repl?
10:45	rhudson	I think the general answer is that use & require are designed for use in programs that are in multiple source files
10:45	gfrlog	okay
10:45	gfrlog	so for things loaded dynamically, "require" is implied, and "use" is done with "refer"?
10:46	rhudson	If use mean 'use is more or less 'require plus 'refer, yes
10:47	gfrlog	and a vanilla 'require does nothing but load a source file
10:47	gfrlog	okay
10:48	rhudson	Well, 'require also allows you to define an alias in the same step.
10:48	gfrlog	yeah
10:48	gfrlog	hmm
10:48	rhudson	If you say (require 'clojure.xml), you have to call clojure.xml/parse
10:48	gfrlog	right
10:48	rhudson	but (require '[clojure.xml :as xml]) lets you call 'xml/parse
10:48	gfrlog	yes
10:49	gfrlog	so if I wanted to dynamically load source strings that thought they were files and wanted to "require/use" each other....
10:49	gfrlog	I'd have to create my own 'ns macro?
10:49	gfrlog	to translate stuff to refer?
10:50	rhudson	If I follow what you're trying to do, yes
10:50	rhudson	"each other" -- you can't have circular dependencies
10:51	gfrlog	right
10:51	raek	there is also 'alias for doing the :as part...
10:51	rhudson	right
10:51	gfrlog	you can't have circular dependencies in a traditional project structure either, right?
10:51	rhudson	right
10:51	gfrlog	okay
10:53	gfrlog	thanks
10:53	rhudson	you're welcome
10:54	raek	splitting up multimethod implementations into multiple files is a situation that can be tricky
10:54	gfrlog	is it possible to interrupt a repl computation without closing the repl?
10:54	gfrlog	Ctrl+C always closes my repl
10:55	raek	I often end up making a foo.bar root namespace, a foo.bar.common ns with the defmulti and some foo.bar.impl-x/y/z with the implementations
10:56	raek	one approach could be to do the long computation in a future
10:57	raek	(future (long-computation-is-looong))
10:57	raek	and if you want to abort it, just do a (future-cancel *1)
11:06	gfrlog	interesting
11:08	raek	I guess it depends on what kind of time-consuming evals you do
11:09	gfrlog	man I'm having trouble with http.agent; I want it to try to connect to a port with nothing listening on it and return false or nil or something, but it just hangs on forever, even when I set both timeout values
11:10	raek	printing infinite seqs and circular structures can be limited by rebinding print-length and print-level
11:10	gfrlog	is that a buggy library? I've had trouble with it before
11:11	raek	I know there is a http://github.com/technomancy/clojure-http-client library that seems to be popular
11:11	raek	contrib is not a official clojure library, just a collection of interesting things
11:11	gfrlog	right
11:12	gfrlog	it's nice to have good things in it though
11:12	gfrlog	rather than as separate projects
11:13	pdk	if it's a collection of interesting things then you have leeway to be fairly fast and loose with what you choose to include for users' convenience :p
11:15	raek	gfrlog: could your problem have something to do with exceptions in the agent?
11:16	gfrlog	I did get a connection time out error in the agent itself
11:16	gfrlog	but the contrib functions are responding strangely
11:16	gfrlog	like done? returns false
11:16	gfrlog	and the exception didn't come until 5 times longer than my timeouts specified
11:17	gfrlog	and error? throws the exception that the agent is holding
11:23	rhudson	Looks like you need to use 'agent-error (in clojure.core) to check for exceptions
11:24	gfrlog	yeah :( that doesn't solve the issue of not being able to control the timeout though
11:57	edbond	is there noop in enlive? I need to remove div#flash only if context map has :error key.
11:57	edbond	tried [:#flash] (if (context :error) nil) but it removed in either case.
11:59	edbond	end up with: [:#flash] (if-not (context :error) nil identity)
12:04	gfrlog	does clojure do any kind of uber-compiling that isn't available for dynamically loaded code? or are all methods of code-loading equivalent?
12:04	gfrlog	(assuming parse-time is negligible)
12:22	jlf`	technomancy: ping
12:23	gfrlog	how do I change the some-value type variables that some libs use for configuration?
12:23	gfrlog	I thought they were vars, which I thought meant using set!
12:23	gfrlog	but clearly I have no idea what's going on
12:25	gfrlog	perhaps 'binding?
12:25	rhudson	or 'with-bindings
12:27	gfrlog	I guess 'let could also work
12:28	raek	let will not work in that case
12:29	raek	(def x 1) (def f [] x) (let [x 2] (f)) ; will return 1
12:29	raek	replace let with binding and it will return 2
12:30	raek	variables are always lexically scoped
12:30	raek	but their values can be dynamically rebound
12:37	gfrlog	I see
12:37	gfrlog	thanks
12:47	daaku	is there a way to find out if there are updates available for a project's dependencies via lein?
14:05	jstirrell`	I'm kinda new at this whole linux thing... what's the easiest way to run a clojure function with cron?
14:09	jstirrell`	would something like "/1 * * * ~/cljproject/lein repl && (namespace/function params)" work?
14:10	raek	you cannot pass input to the repl that way
14:11	raek	you could use the more manual java -cp <jars> clojure.main -e '(namespace/function) (System/exit 0)'
14:11	dnolen	jstirrell: if you want a repl that supports eval from the command line you might wanna take a look at cake, you can do, cake eval "( ... )"
14:11	raek	maybe cljr or cake can run a file as a script without having to specify the classpath manually
14:12	jstirrell`	ok sweet thanks
14:13	raek	you can try to run the command in the terminal so see that everything works before writing it to the crontab
14:13	raek	(edit your crontab with "crontab -e")
14:14	jstirrell`	k
14:14	raek	"~/cljproject/lein" will probably fail, unless you happen to have the lein executable in that directory
14:14	raek	also, "(namespace/function params)" will fail, since it's not a shell command, but clojure code
14:15	jstirrell`	yeah that didn't seem right based on the cron examples I was looking at
14:15	raek	it might be easier to put it into a shell script, where you could set up the working directory etc
14:58	_na_ka_na_	hey guys the clojure compiler can't resolve circular dependencies - how the java compiler does ?
15:00	rhudson	Dunno, but you can use 'declare for forward references
15:02	_na_ka_na_	declaring is not working
15:02	Chousuke	don't do circular dependencies
15:02	_na_ka_na_	maybe I should declare and then require
15:02	rhudson	What are you trying to do?
15:02	raek	_na_ka_na_: dependencies between namespaces or vars?
15:02	raek	declare is only ofr vars
15:04	_na_ka_na_	I have (ns b (:require c)) (defn fn-b [] 2) and (ns c (:require b)) (defn fn-c [] (b/fn-b))
15:04	_na_ka_na_	trying to compile as .. java -cp lib\clojure-1.1.0.jar;src;classes clojure.main -e "(compile 'b)" .. fails
15:04	rhudson	You can't have circular dependencies between namespaces
15:05	_na_ka_na_	but if I have 2 useful namespaces and each wants to use other's fn then ?
15:06	rhudson	Then you need to refactor somehow
15:07	_na_ka_na_	is that because of some design principle/reason or just a limitation ?
15:08	rhudson	Not sure. But you can't really do that in Java either
15:08	_na_ka_na_	I just tried that and it worked
15:08	_na_ka_na_	in Java
15:08	clojurebot	hmm… sounds like your out of heap space
15:10	_na_ka_na_	suppose you have a string ns with a super useful fn str and a math ns with a super useful fn + ... now can't it be possible that they need each other ?
15:11	raek	if the functions are that tightly dependent on each other. maybe they should be in the same namespace?
15:11	rhudson	Sure. Development can go like that. I've done it.
15:12	rhudson	One thing to consider is taking something in the circle and putting it in a separate ns
15:16	rhudson	Say function f is in ns a (because other things in a use it), a requires ns b, and you need to call f from somewhere in b. You can't have b require a. But you can put f in ns c, and have a and b both require c.
15:20	_na_ka_na_	Hmm I get that, but are circular dependencies bad ? Java takes care of them.
15:21	rhudson	I know in Java I've had situations where A and B seem to be fine in a circle, ... until I do a clean build.
15:23	rhudson	I don't know what the technical issues and/or design rationales were in Clojure, but I do think having an acyclic dependency graph between ns's makes it easier to think about the structure of a project.
15:25	rhudson	You can have mutual dependencies (e.g. mutually recursive functions) in a single ns, but then the dependencies are explicit, using 'declare or whatever.
15:27	_na_ka_na_	ok, guess I haven't come across some of the evils of circular deps yet
15:27	_na_ka_na_	rhudson: thanks for taking time to answer
15:28	rhudson	sure
15:28	raek	I'm about to write a patch for clojure issue #404, which branch should I base it on? clojure/master?
15:29	raek	(that is, http://github.com/clojure/clojure, branch master)
15:32	raek	hrm, the 1.2.x branch seems to be more recently updated, I'm using that instead
15:36	edbond	can't get ring wrap-file to work? Any ideas?
15:54	mattikus	is emacs still the best editor/ide for clojure?
15:54	mattikus	with criterion for best being generally most accepted and widely used?
15:55	tomoj	no
15:55	tomoj	there was an anti-emacs revolt
15:55	mattikus	orly?
15:55	qbg	tomoj: When was this?
15:55	tomoj	I think most of the revolutionaries said that if you are already familiar with emacs, it's the best
15:56	tomoj	but that we should not recommend emacs to new clojure users who aren't already familiar with it
15:56	tomoj	and should try to avoid giving the impression that to really use clojure, you have to use emacs
15:56	tomoj	but a majority of clojure users still use emacs, I think?
15:57	tomoj	http://briancarper.net/blog/534/emacs-isnt-for-everyone
15:57	tomoj	that revolutionary is actually an emacs user
15:57	raek	even though emacs possibly is the most used now, but I don't see any reason why vim, eclipse, intellij or netbeans shouldn
15:57	raek	't be used
15:58	mattikus	i'm a vim guy, but i currently use emacs for my very infrequent clojure stuff
15:59	raek	I happen to like emacs, so that's why I use it. I use eclipse and vi frequently too, but I haven't done any clojure developing in those yet
16:00	qbg	CCW works, and is somewhat simple, but I feel Emacs is simpler
16:00	qbg	Maybe because I've used SLIME for so long
16:00	qbg	And my process isn't very advanced
16:01	raek	also, the project management and package management is done by tools outside the IDE (lein, cljr, cake) anyway, so I guess the issue's most about how you prefer to edit text
16:02	mattikus	right
16:02	mattikus	are people focusing on lein?
16:02	qbg	lein is the current de facto standard
16:02	edbond	what for used clone-for in enlive?
16:02	raek	leiningen is great for projects (basically, when you have more than one source file)
16:03	raek	cljr is great for when what you do is not a project
16:03	raek	I've heard rumors that they might merge some day
16:04	mattikus	i havent heard of cljr
16:04	raek	cljr keeps a central repository of installed packages, leiningen keeps dependencies on a per project basis
16:04	raek	which allows different projects to use different versions, etc
16:05	raek	with cljr you don't need a project directory structure with a project.clj to start working
16:05	raek	it makes clojure work more like python and ruby
16:06	raek	if you want to use compojure, you just run "cljr install compojure"
16:06	raek	you can also search for packages
16:07	raek	then, you can easily start a repl with "cljr repl/swingrepl/swank", in any directory
16:07	raek	and all the currently installed packages will be on the classpath
16:17	mattikus	anyone have experience clojure programming with viper mode?
16:24	raek	when running "ant test" on clojure 1.2.x adn master branches, a test in test_pretty.clj fails sporadically
17:04	dsantiago	I'm trying to import a Java class that is called Compiler (in its own library), and when I put that in an import statement, Clojure complains that "Compiler already refers to: class clojure.lang.Compiler." refer-clojure doesn't seem to let me fix this, is there something I can do about this?
17:07	qbg	Don't import it?
17:07	raek	(ns-unmap 'user 'Compiler) worked for me, but I don't know anything about the cause of the problem
17:07	dsantiago	Hm.
17:09	dsantiago	I guess I'll just not import it. It has a really long full name, though.
17:09	daaku	anyone know how to use setup/teardown in lazytest? i've got a Fixture with my setup/teardown functions with reify -- but i'm can't seem to figure out how to use it. i'd like for it to run for top level it/given calls inside a describe
17:09	raek	as you said, (:refer-clojure :exclude [Compiler]) doesn't seem to respect the user's wish
17:50	daaku	is there a form of into-array where i can specify what to cast the objects into? (i have a number of different objects which implement an interface, and the java counterpart needs an array of objects that implement the interface)
17:54	qbg	,(class (into-array Comparable [1 2 3]))
17:54	clojurebot	[Ljava.lang.Comparable;
17:54	qbg	That seems to work
17:56	daaku	qbg: oh, cool. didn't realize that worked
18:41	raek	just sent in my first patch!
18:41	raek	now I will get some sleep
19:13	kencausey	jweiss: Did you resolve http://paste.lisp.org/display/94280 ? I'm seeing that now
19:14	kencausey	oops, my fault, bad project.clj
19:24	vIkSiT	hi all
19:25	vIkSiT	anyone else face this problem with lein 1.2.0 and slime 20100404 : make client process failed: Connection refused, :name, SLIME Lisp, :buffer, nil, :host, 127.0.0.1, :service, 4005 ?
19:25	vIkSiT	(this is with a lein swank inside the project dir)
19:36	kencausey	vIkSiT: You've confirmed there is actually something listening on 4005?
19:36	vIkSiT	kencausey, indeed. I actually swapped out 1.2.0-beta1 from project.clj to master-SNAPSHOT - and it seems to run fine
19:37	kencausey	I'm having problems getting this to work, but I've complicated it perhaps by running under cygwin. Slime won't install from elpa
19:37	vIkSiT	so I'm guessing there's some incompat b/w my setup and 1.2.0
19:37	vIkSiT	sigh
19:37	kencausey	I'm too newbie to be much help I'm afraid
19:40	jarodluebbert	can someone tell me what this does to a function argument? [#^String arg]
19:40	gfrlog	that's a type hint
19:40	jarodluebbert	so it doesn't actually modify the argument?
19:40	gfrlog	it just tells the compiler what sort of argument you're expecting
19:40	gfrlog	for optimization
19:40	gfrlog	I don't think it has any functional effect
19:41	gfrlog	if I'm wrong about that, hopefully somebody else will jump in
19:41	jarodluebbert	hmm, thanks
19:41	gfrlog	np
19:43	jarodluebbert	I want to write a function that lists all files in a certain directory like (my-func "."). I'm using (File. dir) in the function but it's throwing an exception
19:43	jarodluebbert	sorry, this might be easier: http://gist.github.com/513330
19:56	lozh	what are you importing as ds?
19:56	lozh	ah, duck streams...
19:57	jarodluebbert	yeah, it's not the (File. dir) part that's throwing the exception, it's because there are directorys in the tree and duck-streams is trying to read the directory in as a file I think
19:57	jarodluebbert	so I need to recursively do this to read in all files in all sub-directories
20:26	lozh	That's right - not sure how read-lines copes with binary files, either
21:08	vIkSiT	hmm
21:08	vIkSiT	in a function like this : http://paste.lisp.org/display/113305
21:08	vIkSiT	only my last map statement gets executed.
21:08	vIkSiT	any ideas on why?
21:11	rhudson	'get-and-inseert-data is a function with side effects, I presume?
21:16	rhudson	One likely issue is that 'map is a lazy function -- certainly in the first two maps, there's nothing to consume the sequence, so the sequence never gets generated.
21:17	wtetzner_	if you want the side effects executed, wrap your call to map with (dorun ...)
21:24	vIkSiT	oh right
21:24	vIkSiT	rhudson, wtetzner_ - thanks for the suggestions, I think the dorun would work. and yes, get-... is a fn with side effects
21:24	vIkSiT	btw
21:25	vIkSiT	does anyone know how to stop/break a slime execution?
21:26	wtetzner_	try ^C
21:26	vIkSiT	no luck
21:37	vIkSiT	hmm, so assuming I've got a -main function for a program, and I'd like to populate some global variables I represented by +myvar+ ..
21:37	vIkSiT	would a let be the right way to do this?