#clojure – 2011-02-13

2011-02-13

00:02	_Vi	(defmacro qqq [] '(method-name [this] "qqq")) (reify Qqq (qqq)) ;; NullPointerException How to use macros inside reify/defobject?
00:08	_Vi	In general, how to feed output of my macros to a system macros (without of writing a wrapper).
00:08	_Vi	s/\./?/
00:08	sexpbot	<_Vi> In general, how to feed output of my macros to a system macros (without of writing a wrapper)?
00:12	_Vi	How to make my macros stronger than usual macros and expand before usual macros see it?
00:28	_Vi	(deftype Qqq [var1] ...) ;; How to mention "var1" in macro? It says it not found in the namespace. Also referring it by #' fails.
00:40	jkdufair	how would i evaluate a string representation of a class name to a class
00:42	incandenza	(Class/forName "...") perhaps
00:44	jkdufair	thank you!
00:44	incandenza	np
00:54	alex_boisvert	n00b question: I want call "max" on a list
00:54	alex_boisvert	e.g.
00:54	alex_boisvert	(def xs [ 1 2 3])
00:54	alex_boisvert	(max xs) ; doesn't work, need to splat the list; don't know how ..
00:54	brandnewmath	clj
00:54	gregh	(apply max xs)
00:54	brandnewmath	...doh, sorry
00:55	alex_boisvert	gregh: ah, ok, thanks!
03:59	kumarshantanu	is there a shorter way to transform keys in a map than this? -- (zipmap (map transform-fn (keys m)) (vals m))
04:00	brehaut	(into {} (map (fn [[k v]] [(transform k) v]) m))
04:02	replaca	(into {} (for [[k v] m] [(transform k) v])
04:02	replaca	by a few chars :)
04:04	kumarshantanu	berhaut: replace: which is supposed to be faster?
04:04	replaca	kumarshantanu: dunno. I think they're about the same
04:04	brehaut	((comp (partial into {}) (partial map (juxt (comp inc first) (comp transform-fn second)))) m)
04:05	replaca	brehaut: now you're just being whacky!
04:05	brehaut	church of point free!
04:06	replaca	yeah, in haskell it would be beautiful :)
04:06	brehaut	yeah sadly not so much here
04:07	Scriptor	haskell, in theory at least, curries every function call, so it's natural :)
04:08	brehaut	i think that map is a tiny bit faster than for but the difference is less important than the readability
04:09	brehaut	kumarshantanu: if you really need to know how fast something is
04:09	brehaut	use time and dotimes
04:09	kumarshantanu	brehaut: replaca: i am writing a function to do this, so i guess i will go for performance
04:09	replaca	no - I'd love to see a syntax that combined what was beautiful in clojure with what was beautiful in haskell. Rich made some compelling arguments one night about why he though it wasn't possible
04:09	brehaut	kumarshantanu: that is basicly entirely the wrong answer
04:09	replaca	kumarshantanu: I'm with brehaut on this one :)
04:10	replaca	unless it's in an inner loop, the difference won't matter
04:10	brehaut	kumarshantanu: hard numbers and real stats after profiling, or use the nice code
04:10	kumarshantanu	you guys mean i should prefer readability even if i am wrapping this inside a function?
04:10	replaca	yup
04:10	brehaut	absolutely
04:11	replaca	in 6 months when you look at your code again to debug it, the quickness that you can absorb it with would be most important
04:11	kumarshantanu	hmm
04:11	replaca	if it were a 2x difference, then performance might be the deciding issue
04:12	kumarshantanu	i meant to say -- i am writing a function 'map-keys' that will do just this -- but yeah readability is a bigger gain since the perf difference will be tiny
04:12	replaca	but unless it's in an inner loop, it's unlikely to make more than a couple tenths of a percent difference in your runtime.
04:13	kumarshantanu	i agree
04:13	replaca	I found "for" to be very unreadable when I came to Clojure, but it's long since been second nature
04:14	brehaut	replaca: where did you come from?
04:14	replaca	everywhere :)
04:14	brehaut	haha
04:15	replaca	of course I'd used list comprehension in Python before but something about the difference in the form blocked the mapping in my brain for a couple of months
04:15	brehaut	kumarshantanu: heres a question: why do you think there is no map-keys in the standard lib?
04:15	replaca	map is the same as most every language that has it (esp. CL), so it was easy
04:16	brehaut	replaca: huh thats really interesting
04:17	replaca	yeah, dunno why. It seems so obvious now that the block is broken
04:20	LauJensen	Morning guys
04:20	brehaut	Morning Lau
04:22	Scriptor	morning LauJensen
05:25	_ulises	morning
05:29	_ulises	anybody doing hadoop stuff with clojure? anybody got any recommendations regarding which libs to use, etc.?
05:32	LauJensen	_ulises: I blogged about one lib, 1) http://bestinclass.dk/index.clj/2010/01/hadoop-installation.html 2) http://bestinclass.dk/index.clj/2010/01/hadoop-feeding-reddit-to-hadoop.html
05:33	_ulises	thanks LauJensen :)
05:33	_ulises	I was just trying to run the examples of the clojure-hadoop lib (alex ott's fork) but I get weird errors unfortunately, will read your posts, ta
05:39	cpfr	_ulises, cascalog
05:39	_ulises	cpfr: I did see that one, however I want to do plain hadoop for the moment but thanks anyway
06:09	_ulises	is any of the clojure-hadoop libs on clojars the preferred one? according to LauJensen's post they are broken?
06:10	cpfr	i used stuart's lib
06:25	_ulises	right, I tried one of the forks but it didn't quite work for me; perhaps I should try Stuart's lib then
07:14	xkb	hello
07:14	xkb	Is anyone here using clj-oauth with delicious?
08:16	bulters	g'day all
08:48	_ulises	does anybody know how I can pass -XmxNNN to lein swank?
08:50	_ulises	ah, found it, nm
08:54	Dranik	_ulises, how did you manage that?
08:54	_ulises	Dranik: JVM_OPTS=-Xmx1024M lein swank
08:55	_ulises	from https://github.com/technomancy/leiningen/blob/stable/resources/script-template
08:55	Dranik	thanks
08:56	_ulises	np
09:12	_ulises	hrm, I'm having a hard time making this clojure-hadoop thing work. If I run from the repl (run job) (where job was defined with defjob as per the wordcount examples) the jobs run fine, but the minute I try running a job from the command line with java -cp it all blows up, anybody got experience with this lib and is willing to give me a hand? :)
09:15	raek	is there any documentation for the contract of the .equiv method of clojure.lang.IPersistentCollection?
09:48	khaliG	is there a way to wrap a var on a struct?
09:55	khaliG	dont know if my last message went through but i'm wondering if it's possible to wrap a Var on a struct. Otherwise i'm guessing you'd have to use an atom and access the fields in a sync block thing.
09:57	Cozey	is there something like (get-in ) but for vectors as well?
09:59	opqdonut	get-in works for vectors
09:59	opqdonut	,(get-in [[0 1 2] [3 4 5]] [1 1])
09:59	clojurebot	4
10:03	raek	khaliG: what do you mean by "wrap a Var on a struct"?
10:03	raek	could you give an example on what you want to do?
10:04	khaliG	i mean (ref <a-struct>)
10:04	Chousuke	and?
10:04	Chousuke	that works just fine
10:04	Chousuke	though in most use cases you'll probably want a record instead of a struct
10:05	khaliG	ok
10:06	Chousuke	though I'm suspicious now. are you sure you need refs at all?
10:07	Chousuke	using refs just because you think you need to mutate something is usually wrong :)
10:07	khaliG	it's possible i'm wrong :)
10:07	Chousuke	that is, there might be a solution that doesn't require mutation at all
10:07	Chousuke	and you should prefer those
10:08	Chousuke	The less "mutable" elements your design contains, the easier life will be.
10:08	Chousuke	hmm, fewer*
10:08	khaliG	understood, though i dont know if i could do this without mutation, i'm accumulating some values
10:09	Chousuke	reduce?
10:09	raek	sounds like a job for reduce
10:09	Chousuke	your accumulator does not have to be mutable
10:11	khaliG	yea let me think but my gut feelign is it's not possible to do without mutation here
10:11	Chousuke	describe what you're trying to do and maybe we can help
10:12	khaliG	Ok. i have an exercise model which consists of tables of values for each exercise (sets, reps weight etc), and a workout model which consists of exercises and a few other datums. The data is entered by the user via a Swing UI, and i store the imputs in clojure structs and vectors
10:13	khaliG	could i do away with mutation or do i need to provide more information?
10:13	Chousuke	so you need to update the models?
10:13	khaliG	correct
10:13	Chousuke	right, for that part, you'll need a ref or something
10:14	Chousuke	but that's only for the final storing of the updated value
10:14	Chousuke	most of the related code you can write without mutation
10:14	khaliG	yes i have written it that way :)
10:14	Chousuke	sounds like you're on the right track then
10:15	khaliG	atm i have this call (send data conj model) which would work fine if data was a vector, but its not a struct and that's where i got stuck
10:15	Chousuke	you can use update-in
10:15	khaliG	it worked fine before though as long as my data was in that vector (data)
10:15	khaliG	ooh, let me read about update-in
10:15	Chousuke	(send data update-in [:key] conj whatever)
10:15	khaliG	that sounds perfect!
10:16	Chousuke	I like the chaining aspect of update functions
10:17	khaliG	i was unwittingly seeking somethign like that, now that've mentioned it
10:17	Chousuke	there's also assoc-in
10:17	khaliG	thank you
10:21	bulters	what's the current-easiest-way of doing the whole emacs-clojure-repl dance these days?
10:21	bulters	I keep losing track of which guide to read ;-)
10:22	khaliG	bulters, on which platform?
10:22	bulters	os x
10:23	khaliG	not sure about os x, but linux was painless using the emacs package installer thing. i had problems on windows though
10:24	_ulises	bulters: do you mean installing or running/devving?
10:24	bulters	_ulises: well, already got clojure installed (via leiningen)
10:25	_ulises	I usually add swank-clojure to my :dev-dependencies
10:25	_ulises	and I just discovered a super-neat trick of leiningen, which is to have a checkouts/ dir in your project with symlinks to other projects you're hacking in parallel
10:26	_ulises	leiningen picks those up automatically so you don't need to restart your swank server, etc. etc.
10:26	bulters	And I guess installing the swank-clojure and slime packages might help as well...
10:27	_ulises	yup, that's how I do it. I've tried eclipse but I'm sort of used to using emacs in my daily routine so...
10:27	khaliG	pretty much, and then you start swank in your clojure project, and M-x slime-connect in emacs
10:27	bulters	_ulises: you add them as git (or s/ by your favorite scm) submodules?
10:27	_ulises	bulters: atm I'm issuing lein jar as I'm testing launching my app through java
10:27	_ulises	and that rebuilds the dependencies, etc.
10:29	bulters	cool
10:30	_ulises	if I have an fn [ args ] how can I detect if args is iterable/seqable? say I can either pass it a map or an fn?
10:30	_ulises	there's fn? for that, but for maps?
10:31	bulters	oh this is nice... :D thanks for the quick pointer...
10:31	_ulises	,(doc map?)
10:31	clojurebot	"([x]); Return true if x implements IPersistentMap"
10:31	_ulises	bleh
10:31	_ulises	bulters: sure, np :)
10:41	rlb	I was looking at the tutorial posted here the other day (http://mmcgrana.github.com/2010/07/develop-deploy-clojure-web-applications.html), and for some reason, the POST handler isn't receiving any form arguments. They're {}. Any idea what I might be doing wrong?
11:05	raek	bulters: install clojure-mode, slime, slime-repl in emacs with package.el, :dev-dependencies [[swank-clojure "1.2.1"]] in project.clj, lein deps, lein swank and then M-x slime-connect from emacs
11:06	raek	most importantly: do not use the deprecated swank-clojure _emacs_ package
11:07	khaliG	hm so don't install swank-clojure at all?
11:07	khaliG	i've got 1.1.0 installed
11:07	raek	bulters: using technomancy's clojure-starter-kit gives you package.el with correct settings. see the docs on http://github.com/technomancy/swank-clojure/
11:07	raek	khaliG: the clojure lib or the emacs package?
11:07	khaliG	emacs package
11:07	raek	no.
11:07	khaliG	oops, okay
11:07	raek	it is from pre-leiningen ties
11:07	raek	*times
11:08	raek	use durendal (another project of technomancy's) if you want a quick way of launching the swank server from emacs
11:48	bulters	raek: thanks, I've tried the starter kit; but decided to roll my own... part of the emacs learning process :P
11:51	bulters	durendal looks nice though...
12:27	xkb	Is anyone here using clj-oauth with delicious-api?
12:28	xkb	or anything requiring Authentication headers
12:34	thorwil	i'm trying to follow https://github.com/gcv/appengine-magic#readme. but how do i get into my applications core namespace on the repl?
12:35	raek	thorwil: you mean something like (in-ns 'the-namespace)?
12:36	thorwil	i guess with in-ns, but the right argument to not trigger a no-source eludes me
12:36	raek	(C-c M-p in emacs)
12:36	raek	ah, you need to load it first (require 'the-namespace)
12:36	raek	(C-c C-k in emacs)
12:37	raek	(doto 'the-namespace require in-ns) is a nice combo
12:37	thorwil	ah, not sure what "lein repl" does or doesn't, in that regard
12:37	thorwil	but i was also missing the '
12:37	raek	all it does is to launch clojure with the correct classpath. it does not load any namespaces except clojure.core
12:38	raek	yeah, they are functions, so you have to quote the symbol.
12:38	raek	(unlike the corresponding :require and :use features of 'ns')
12:38	thorwil	i know in principal, but i'm just starting with my first lisp here ;)
12:39	thorwil	thanks!
12:39	raek	np.
12:40	xkb	aargh again wrong signature.. hmm oauth is bleh
12:40	raek	xkb: have you tried asking at the clojure or clojure-web-dev google groups?
12:43	xkb	raek: not yet, will keep on tinkering for about 1 hour. And if that fails, Ill ask :)
12:43	xkb	the fault is prob. in the encoding of the uri/params
12:45	raek	ring has some utility functions for param encoding in uris
12:45	khaliG	aw, slurp/spit wont work with Java Dates? :/
12:46	raek	khaliG: they operate on strings
12:46	khaliG	k
12:46	raek	so you need to do the string <-> date conversion yourself
12:46	khaliG	understood
12:46	khaliG	its the only object remaining which isn't a readable string afaik
12:47	khaliG	(in my code i mean)
12:47	raek	for clojure data structure, you can just use read-string and pr-str
12:48	khaliG	nice
12:48	raek	spit will call str (which corresponds to java's toString method) on its argument, which does not work for all kinds of data
12:49	khaliG	seems Date has a toString method
12:49	khaliG	but i can't see a fromString
12:49	raek	,(str (lazy-seq [1 2 3]))
12:49	clojurebot	"clojure.lang.LazySeq@7861"
12:49	raek	,(pr-str (lazy-seq [1 2 3]))
12:49	clojurebot	"(1 2 3)"
12:50	khaliG	maybe i can use a different time structure, lets see if there are any clojure libs for that
12:50	raek	khaliG: Joda time is a much better lib for working with dates in java. the clojure port is called clj-time
12:50	khaliG	oh nice!
12:52	khaliG	hm perhaps i can just write my dates as longs and then read them back
12:53	khaliG	i'd rather not do any sort of marshalling though
12:53	khaliG	i'll explore jodatime
12:53	khaliG	thanks raek
12:53	raek	yeah, milliseconds since the epoch (in UTC time) as a long is a pretty universal representation
13:35	khaliG	i love how i'll make a change to a running swing program, move to restart it after making a change and realising i just need to recompile the changed method
13:46	pppaul	hey, i'm getting an error with spit
13:46	pppaul	java.lang.Exception: Cannot change an open stream to append mode.'
13:46	pppaul	i'm using conrtib/append-spit
13:53	raek	pppaul: is the file writable? also, you can use spit from clojure core since 1.2: (spit "file.txt" the-string :append true)
13:53	pppaul	oh, thanks
13:53	pppaul	that's much cleaner
13:53	pppaul	spit is making the file
13:54	pppaul	i'll change my code to your suggestion
13:56	pppaul	i don't get the error now
14:53	thorwil	is that normal that the repl in emacs doesn't react anymore after i started a jetty server (via appengine-magic)?
14:56	rlb	It looks like none of the :input parameters from the example are making it to the POST handler. Can I get jetty (or clojure) to be more verbose wrt the actual POST?
14:56	rlb	s/clojure/compojure/
14:56	sexpbot	<rlb> It looks like none of the :input parameters from the example are making it to the POST handler. Can I get jetty (or compojure) to be more verbose wrt the actual POST?
15:06	brehaut	rlb is there a logging middleware you could use?
15:13	bobo	what is a good way to do something that should run every 5sek in clojure? should i use executors and such from java?
15:15	brehaut	(doto (Thread. (fn [] (while true (let [t (calc time now)] (do-action) (Thread/sleep (- 5000 (- now t))))))) .start)
15:15	brehaut	pretty blunt
15:16	brehaut	i guess you could use an agent
15:16	brehaut	instead of an explicit thread
15:17	bobo	Thread feels very blunt, then exexutors feels nicer
15:20	brehaut	(defn tick (agent nil)) (defn act [v] (do-something) (Thread/sleep 5000) (send tick act))
15:20	brehaut	thats with agents and minus the math to make it a bit more precise
15:20	raek	bobo: there is a executor class for scheduling repeating tasks
15:21	raek	http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ScheduledExecutorService.html
15:22	raek	http://download.oracle.com/javase/6/docs/api/java/util/concurrent/Executors.html#newScheduledThreadPool(int)
15:22	raek	bobo: also, cron4j works wonderfully when you need to schedule tasks as you would with unix cron
15:23	rlb	brehaut: don't know -- I was just trying the example posted here the other day. I'm not all that familiar with compojure/hiccup/ring/etc. yet.
15:24	rlb	the POST comes in, but :params is {}.
15:25	raek	thorwil: I don't know exactly how appengine-magic starts the jetty server, but if you start jetty manually, you can give it the :join? false option to not block until the server is shut down
15:27	raek	cron4j example (I just love how simple it is):
15:27	raek	(defonce scheduler (doto (it.sauronsoftware.cron4j.Scheduler.) (.schedule "30 16 * * 1-5" #'my-fn) (.start)))
15:28	raek	this executes my-fn 4:30 PM every monday-friday
15:28	bobo	raek: yeh i know they ar ein java :-) just thought if there was something nice in clojure. but il use the java stuff then
15:28	brehaut	rlb: what middleware do you have running?
15:29	_Vi	Why when I issue "(ns ...)" in REPL I lose access to "doc" function?
15:29	rlb	brehaut: ring.adapter.jetty? Starting it like this: (run-jetty #'main/app {:port 8080})
15:29	brehaut	rlb thats your adapter rather than middleware
15:29	replaca	raek: do you have the leiningen :depends line for cron4j handy?
15:30	brehaut	i dont know of compojure automatically includes ring.middleware.params or similar
15:30	rlb	brehaut: Other than that, just using compojure and hiccup. See here:
15:30	brehaut	hiccup isnt relevant here
15:30	rlb	http://mmcgrana.github.com/2010/07/develop-deploy-clojure-web-applications.html
15:31	raek	bobo: well, I made a library that does some of these stuff (not the Scheduled vareity of executors though) by some pretty redundant functions: https://github.com/raek/lcug-concurrency/blob/master/src/se/raek/lcug/concurrency.clj#L208
15:31	rlb	I adjusted the POST handler like this: (POST "/" x (prn x) ...)
15:31	raek	replaca: I found this: [org.clojars.ghoseb/cron4j "2.2.1"]
15:31	rlb	so I could see x, and I can see that params is {}
15:32	bobo	raek: il take a look!
15:32	raek	iirc, it wasn't in the maven repo, but someone had pushed it to clojars
15:32	rlb	(on stdout)
15:32	rlb	I just wondered if that example might be stale somehow, i.e. the form set up wrong or whatever...
15:32	raek	bobo: basically, all the fns look like this: (defn submit [exe task] (.submit exe task))
15:33	brehaut	rlb im not an expert on compojure sorry
15:33	raek	I'm thinking about generating clojure/autodoc-style docs from javadocs
15:33	raek	so that people don't miss what's directly usable from java...
15:34	raek	bobo: also, did you see my post re executors in clojure?
15:34	brehaut	raek: that would be handy for the not-from-java people like me
15:34	bobo	raek: i dont think i did?
15:34	raek	http://blog.raek.se/2011/01/24/executors-in-clojure/
15:35	rlb	brehaut: np, and thanks.
15:37	brehaut	rlb may i suggest putting together a simple middleware to print out the entire request before it goes into compojure?
15:37	brehaut	there is an example in the tutorial you are working through that shows how to install ring middleware with compojure
15:38	brehaut	your middleware will be approximately (defn log-request [handler] (fn [req] (prn req) (handler req)))
15:53	mreynolds	newb question : I'm doing (doseq (keys map) ...) and I'm getting this error : error: java.lang.IllegalArgumentException: doseq requires a vector for its binding (core.clj:12)
15:53	mreynolds	Do I have to wrap the returned seq in a vector (or convert it?)?
15:54	opqdonut	(doseq [k (keys map)] ...)
15:54	opqdonut	now the variable k will get bound to each key of the map in turn
15:54	mreynolds	duh
15:54	mreynolds	Thanks
15:59	thorwil	raek: seems :join? did the trick. strange how without, some operations work and other just hang there. thanks!
16:00	rlb	brehaut: ok, thanks again.
16:15	rlb	brehaut: post prints as {... "application/x-www-form-urlencoded" ... :body #<Input org.mortbay.jetty.HttpParser$Input@5f4f5a31>}
16:18	brehaut	rlb can you put the ring.middleware.params/wrap-params middleware in before your logging middleware?
16:23	rlb	brehaut: like this? (def app (-> #'handler (wrap-params) (log-request)))
16:23	rlb
16:24	brehaut	swap wrap-params and log-request
16:24	shortlord	are there any simple RPC frameworks for clojure? (I just need something to call clojure functions remotely on client and server)
16:25	brehaut	shortlord: what kind of RPC?
16:25	raek	rlb: the last middleware will be the one that sees the request first and the response last
16:25	raek	moustache reverses this in its syntax
16:26	raek	...since it becomes the outermost wrapping middleware
16:27	brehaut	shortlord: if its not for real work then i have an xml-rpc library that works with ring and provides both sides of the rpc stack, but i dont like xml-rpc and wouldnt recommend it for a real world system
16:27	shortlord	brehaut: I have an application that I need to split into a server and a client that renders the server contents and calls some server functions depending on user input. Nothing fancy, simply calling clojure functions remotely (both client and server are clojure-based) would be enough (similar to java RMI)
16:28	technomancy	shortlord: try clojure.contrib.server-socket/socket-repl
16:28	shortlord	brehaut: priority is not performance, but fast and easy integration into existing non-distributed code
16:28	technomancy	though I guess you would rather have socket-rep
16:28	rlb	brehaut, raek: thanks - that fixed it. I was starting with the first example on that page, and it doesn't use middleware (wrap-params, etc.).
16:29	brehaut	shortlord: github.com/brehaut/necessary-evil
16:29	brehaut	if technomancy's solution doesnt work for you
16:29	brehaut	shortlord: but i wouldnt recommend it
16:30	shortlord	brehaut: ok, thx a lot
16:31	shortlord	I've thought about using a simple remote repl, but it would be quite insecure to pass any kind of string and evaluate it. So I guess I would have to build a custom check that only allows the execution of predefined functions, right? Does something like that already exist?
16:32	brehaut	shortlord: if you use a repl yeah you'd have restrict it somehow. cljail might help there
16:33	brehaut	you need to explicitly expose functions with necessary-evil
16:35	shortlord	brehaut: searching for cljail does not give me any results, do you mean clj-sandbox?
16:35	brehaut	shortlord: honestly im not sure. whatever raynes and amalloy's project is called
16:36	brehaut	https://github.com/Raynes/clojail
16:38	mreynolds	More newbness : What's the idiomatic way to lookup data from nested maps? Like {:a {:b "b" :c "c"}}, where I want to get :c's value.
16:39	brehaut	,(get-in [:a :c] {:a {:b "b" :c "c"}})
16:39	clojurebot	nil
16:39	raek	making a custom interpreter for a limited command set (possibly using the clojure reader) sound much more secure
16:39	shortlord	brehaut: cool, thx a lot for the link
16:40	mreynolds	nice, thanks!
16:40	brehaut	,(get-in {:a {:b "b" :c "c"}} [:a :b])
16:40	clojurebot	"b"
16:40	brehaut	mreynolds: if i got it round the right way :P
16:40	mreynolds	brehaut: No worries, I'm still mapping out functions, so just having the pointer is good enough
16:40	brehaut	mreynolds: its part of a family including assoc-in and update-in
16:41	brehaut	mreynolds: clojuredocs.org/quickref/Clojure%20Core
16:41	mreynolds	brehaut: I'll go check those out. I bought clojure in action and joy of clojure and I've been piece-meal making my way through them.
16:44	mreynolds	brehaut: I sort of wish the clojure docs would have an alternate structure similar to how the code is laid out. I find myself looking at the source often and seeing the functions that are "similar" to that function (as you mentioned, assoc-in and update-in are right next to each other), but aren't in the docs
16:47	brehaut	mreynolds: projects using marginalia have that
16:47	mreynolds	brehaut: Haven't used that yet, I'll go look at it
17:14	mreynolds	Similar question : I'm building a data structure to allow people to specify files to "watch" in special ways. I was building nested data structures ({:stuff {:type "dir", :other-type "otherdir}}) and get-in let me get those nested pieces of data easily. I now want to, basically, walk the data structure, looking at the "dir"s and replace them with actual File objects. I thought about doing this with zippers, but I wanted to ask
17:16	chouser	zippers would work
17:17	chouser	mreynolds: you might also try clojure.walk
17:17	mreynolds	chouser: I'll look at both, thanks for the pointers
17:18	mreynolds	chouser: Walk looks pretty damned perfect
17:18	mreynolds	chouser: Thanks
17:18	chouser	np
18:00	replaca	raek: belated thank you!
18:03	rata_	hi
18:07	aleksander	hi
18:09	michaeljaaka	hi
18:09	michaeljaaka	is there anyone live?
18:10	brehaut	michaeljaaka: probably
18:10	michaeljaaka	:) thanks, I thought that i have something wrong configuration
18:10	michaeljaaka	no welcome message, no activity messages
18:10	michaeljaaka	etc.
18:48	_Vi	Is there somewhere official use case lists for Atoms, Agents and Refs? E.g. a task where only Atom suits (but not Agent or Ref), a task for Agent...
18:50	jacortinas	_Vi: afraid not, but that would be pretty awesome resource
18:52	_Vi	For example logging somewhere from multiple threads. Agents are OK, but atoms and refs are likely not.
19:08	gfrlog	I wonder if agents are implemented with atoms
19:26	_Vi	Why "alter" and "send" do not end with exclamation point, but "swap!" does?
19:27	pdk`	it's just a typical little idiosyncracy i guess
19:27	_Vi	Having trailing "!" makes feeling of some unsafety.
19:28	pdk`	i dunno why there can't just be some sort of update! function that works on refs/atoms/agents all alike
19:28	Chousuke	alter and send are safe in dosync
19:28	pdk`	maybe have a keyword arg for it when you need send-off style behavior or something
19:28	Chousuke	swap! isn't
19:29	_Vi	When I writing my own functions, when should I finish their names with "!"? Is there some convention there?
19:31	pdk`	! implies that the function is destructive or carries side effects beyond returning a value
19:32	pdk`	it's an old convention from scheme where the functions that did destructive stuff with lists had !
19:32	pdk`	and since refs/agents/atoms are the only mutable forms of data you'll be working with often in clojure outside of java interop well
19:33	_Vi	pdk`, For example, should some "printDebugLog" be "printDebugLog!"?
19:33	pdk`	it doesn't seem necessary there
19:33	pdk`	though note that lisp function naming convention would favor print-debug-log over printDebugLog
19:34	Chousuke	well actually
19:34	_Vi	Is the rule like "put ! if it have side effects and it is not obvious"?
19:34	Chousuke	the convention is to use ! if the function is unsafe in dosync and it's not obvious
19:34	pdk`	you'd be fine with that route i think
19:35	pdk`	in scheme ! was basically a warning that the function you were using could modify the list you passed to it in-place without any other advance warning
19:35	Chousuke	eg. spit etc. are unsafe, but it's obvious so there is no bang
19:35	_Vi	(BTW should it be "unsafely-check-some-condition?!" or "unsafely-check-some-condition!?")
19:35	pdk`	and in clojure none of the basic data structures are mutable outside of storing them in refs/agents/atoms
19:36	Chousuke	but swap! has the bang because you might not think that it's unsafe in dosync forms
19:36	Chousuke	_Vi: have two functions? :P
19:36	Chousuke	(predicate? (some-unsafe-stuff!))
19:37	_Vi	Chousuke, Means the "predicate" with side effects.
19:37	Chousuke	predicates shouldn't have side-effects :/
19:37	pdk`	the idea he's getting at is to have a function that does the unsafe stuff and returns some value
19:37	pdk`	then checking that value against a safe predicate
19:38	_Vi	Also: Should I consider the function side effects free if it actually have debug-only side effects (such as printing in some log or incrementing statistics counter)?
19:38	Chousuke	no
19:39	Chousuke	unless you can disable that behaviour in production code
19:39	_Vi	For example, when debugging is switched off (release version) it becomes truly side-effects-free.
19:40	Chousuke	you'll get some funky debug output if you use such functions in transactions though :)
19:40	dnolen	_Vi: ! is really to indicate changing a "place" in a way that that doesn't specify any "time management" strategy. alter doesn't need it, they are inside dosync. agents imply uncoordinated concurrency.
19:41	Chousuke	dosync handles sends specially, which is why send doesn't have the bang
19:43	pdk`	i wouldn't bother if it doesn't change anything that's relevant to an outside caller of the function
19:43	pdk`	if it's closed over some counter that's just there for debugging and doesn't affect the behavior of any functions or modify other outside state then whatever basically
19:46	Chousuke	well, yeah.
19:46	Chousuke	as long as the side-effect is inconsequential to the program it's fine I guess :P
19:47	_Vi	Chousuke, So I can add "invocation counter" statistics without fear being bad guy.
19:47	_Vi	s/fear/fear of/
19:47	sexpbot	<_Vi> Chousuke, So I can add "invocation counter" statistics without fear of being bad guy.
19:48	Chousuke	_Vi: it's just a bit dirty, but I guess you can.
19:48	Chousuke	_Vi: at least use a macro or something you can easily disable :)
19:49	Chousuke	then when you ship a release version, just define the macro to return nil or something :P
19:49	Chousuke	in essence making it a comment
19:55	_Vi	What should I do if I want to have a macro that expands in two (or more) forms? (and I cannot use "(do ...)" because of it is not a code)
19:56	brehaut	_Vi, use do
19:56	_Vi	brehaut, This is not a code. It is either data or some internals of "reify" or "let" or whatever.
19:57	brehaut	then use functions
19:58	_Vi	The only not-so-nice solution I see is to wrap containing for in macros that will handle this duplication.
19:59	johnhunter	hi, I have a noob question
19:59	brehaut	johnhunter: you are welcome to ask it
20:00	johnhunter	thanks, i am writing a swing app, and i want in a text field to let the user write some clojure code - a dsl if you will
20:00	johnhunter	when I get the text, i call (eval text)
20:01	johnhunter	it seems eval runs from the clojure.core namespace, not my app's namespace
20:01	johnhunter	so none of my def'd data values are found
20:01	_Vi	johnhunter, Example:
20:01	_Vi	(eval (read (java.io.PushbackReader. (java.io.StringReader. "(+ 4 5)"))))
20:02	johnhunter	yes, thanks, that is roughly what i am doing, and it works for (+ 4 5)
20:02	brehaut	johnhunter: there is a with-ns function defined somewhere
20:03	johnhunter	oh.. let me look that one up
20:03	brehaut	just cant workout where 'somewhere' is
20:04	johnhunter	http://richhickey.github.com/clojure-contrib/with-ns-api.html
20:04	brehaut	that would be it
20:07	johnhunter	the only thing is eval seems to start from clojure.core, and it knows nothing about with-ns from contrib
20:07	johnhunter	i'm very fuzzy on all this namespace stuff
20:07	brehaut	i would have assumed that (with-ns namespace (eval ...)) would have fixed that?
20:07	brehaut	alternatively
20:08	johnhunter	oh, i think you might be right... i just have to include that contrib in my main app
20:08	johnhunter	i'll try that, thanks
20:08	brehaut	(eval (concat (list with-ns namespace exp)))
20:08	brehaut	wait madenes
20:08	brehaut	(eval (list 'with-ns namespace exp))
20:09	philipo	clojure
20:18	johnhunter	it doesn't seem to resolve with-ns shouldn't i get it by including clojure-contrib in my project.clj like ... :dependencies [[org.clojure/clojure "1.2.0"]
20:18	johnhunter	[org.clojure/clojure-contrib "1.2.0"]]
20:18	brehaut	have you got a use or require in your ns?
20:18	johnhunter	:require
20:20	johnhunter	how do i check if it is in clojure.contrib 1.2?
20:20	brehaut	are you referencing with-ns with the fully qualified project?
20:20	brehaut	it is
20:21	johnhunter	nope, just (with-ns myns.core (eval ....)
20:21	brehaut	there you go then; with a require you need to qualify any functions in that namespace
20:21	brehaut	so if you have bare require, you need clojure.contrib.with-ns/with-ns
20:21	brehaut	if you have an :as require
20:22	johnhunter	ah...
20:22	brehaut	(eg (:require [clojure.contrib.with-ns :as with-ns]))
20:22	brehaut	you do just with-ns/with-ns
20:22	johnhunter	and what if i just want to call (with-ns ... ?
20:22	johnhunter	:use ?
20:22	brehaut	use use
20:23	brehaut	IMO - dunno if its considered idiomatic - you should prefer requires to uses, and if you do decided to use a use, you should qualify all the imports with only
20:23	johnhunter	ok, for some reason this namespace stuff won't stick in my brain
20:23	brehaut	eg (:use [clojure.contrib.with-ns :only [with-ns]])
20:25	brehaut	i generally use aliased requires except for some operators or forms that are cleaner (and clear where they from) when used
20:43	gfrlog	brehaut: now that I've waited a day, do I get to hear what you were thinking of?
20:43	brehaut	declare
20:43	brehaut	perhaps with a with-ns ?
20:43	gfrlog	yes, I think that would do it
20:44	gfrlog	I tried it with a fully qualified symbol but I don't think that works
20:44	brehaut	however, given ive had a day, i think that probably i was wrong given your requirement to declare something in another ns
20:44	gfrlog	wrong how?
20:44	gfrlog	that hiredman wasn't thinking of that?
20:44	brehaut	that it might not work?
20:44	brehaut	both
20:45	gfrlog	I'll see if it works...
20:45	brehaut	hiredman is much better at this than i am
20:45	brehaut	absolutely worth a shot
20:45	gfrlog	do you think either you or him were suggesting that it's better code than my eval version? Or just that eval isn't strictly necessary?
20:46	brehaut	using eval is a fairly good sign somethings been overlooked
20:46	brehaut	its more of an implementation tool than a usage tool
20:46	gfrlog	so you prefer several lines of non-eval code over one line of eval code?
20:46	brehaut	yeah typically
20:47	brehaut	im not convinced you should need to fire up the compiler for small things
20:47	brehaut	those couple of lines could be abstracted to declare-with-ns or soemthing and become a library function
20:47	tomoj	how do you avoid eval?
20:47	gfrlog	that's a good point
20:48	gfrlog	tomoj: apparently by using with-ns and declare
20:48	gfrlog	but actually I'm sure that wildly depends on what you're using it for
20:48	brehaut	tomoj: thats a guess on my part. i think hiredman was sure of a good way to do it though
20:48	gfrlog	,(eval "2893")
20:48	clojurebot	DENIED
20:48	gfrlog	,(Integer. "2893")
20:48	clojurebot	2893
20:49	brehaut	yeah your not going to get to execute arbitrary code in the bots
20:49	gfrlog	(eval '(println "DENIED"))
20:49	gfrlog	,(eval '(println "DENIED"))
20:49	clojurebot	DENIED
20:49	brehaut	haha
20:49	tomoj	there were ways with sexpbot recently
20:50	tomoj	there may still be
20:50	gfrlog	brehaut: I had not thought of what I was doing as "firing up the compiler" until you put it that way
20:51	gfrlog	now I am a better man
20:51	brehaut	bbs coffee
20:52	tomoj	how would either of with-ns or declare help?
20:54	gfrlog	tomoj: that was specific to my case
20:55	gfrlog	for your question, you have to show how you're using eval first
20:55	tomoj	I believe I remeber your case
20:55	gfrlog	okay, well for my case...
20:55	tomoj	and don't see how it would help
20:55	gfrlog	he thought that the specific var whose value I wanted to execute could be created before the library is loaded
20:56	gfrlog	by... (with-ns 'my.namespace (declare go))
20:56	gfrlog	I just tried that on my code and got strange results
20:57	tomoj	I didn't actually remember your case
20:57	gfrlog	so apparently it doesn't do the same thing as ((var-get (find-var 'my.namespace/go)))
20:57	tomoj	since you were talking about eval too I thought you were the one eval'ing gui input
20:57	gfrlog	oh, no
20:57	gfrlog	my case is from yesterday
20:57	gfrlog	I have a program where most of the code is loaded at runtime
20:58	gfrlog	the entry point to that code is where I call (my.namespace/go)
20:58	gfrlog	but the compiler won't let me do that since it doesn't know about the namespace yet
20:58	gfrlog	so I was doing (eval '(my.namespace/go))
20:58	gfrlog	which worked just fine
20:58	gfrlog	but offended everybody's sense of decency
20:58	tomoj	right, I see
20:59	gfrlog	I'm still doing the (find-var) thing
21:04	rata_	gfrlog: I think it's not the compiler that doesn't know about the namespace
21:04	gfrlog	rata_ my being wrong would not surprise me, as the whole issue of the clojure compiler gets me fogged up -- what would you say that it is?
21:05	rata_	the evaluator
21:05	rata_	(if that's the name for what executes your code at runtime)
21:05	gfrlog	hmm
21:06	gfrlog	but my code should work at the time it's evaluated
21:06	rata_	and I thought yesterday hiredman was referring to the (intern ns name) fn
21:06	gfrlog	,(doc intern)
21:06	clojurebot	DENIED
21:06	gfrlog	ew
21:06	rata_	do you get your error when compiling your code?
21:06	gfrlog	"lein compile" you mean?
21:06	rata_	~(doc intern)
21:06	clojurebot	gitdoc is http://github.com/Lau-of-DK/gitdoc/tree/master
21:07	rata_	gfrlog: for example... or (compile ...)
21:07	gfrlog	I'll try lein compile
21:07	rata_	or C-c C-k en slime
21:09	gfrlog	rata_ my religion doesn't permit me to use slime
21:09	rata_	ok np
21:09	gfrlog	rata_: lein compile gives the expected ClassNotFoundException
21:09	rata_	ok, so it's the compiler effectively
21:09	rata_	my fault
21:10	gfrlog	np
21:11	gfrlog	rata_: when I try intern at the repl using symbols, it complains that the not-yet-existing namespace isn't found
21:11	rata_	then intern won't solve the problem either
21:11	gfrlog	I don't see it as a problem. Just a mystery of what hiredman was thinking of.
21:12	rata_	intern is a fn so it won't solve anything at compile-time I think
21:12	gfrlog	var-get and find-var are both fns, I assume, and they sufficed
21:14	rata_	yes, but you use them to not have to evaluate the symbol... you give the symbol quoted
21:15	rata_	(is that proper english?)
21:15	gfrlog	right -- you're hoping to find something that allows the symbol unquoted?
21:15	rata_	yes
21:15	gfrlog	sure looked like english to me
21:15	gfrlog	yeah, I guess a macro could work that out pretty easily. I guess then you're looking for an existing macro in clojure.core or something?
21:18	rata_	when I compile code that mentions a non-existent var or a non-existent namespace, it doesn't give me a ClassNotFoundException
21:19	gfrlog	,(why.wont.this/work?)
21:19	clojurebot	java.lang.ClassNotFoundException: why.wont.this
21:19	gfrlog	like that?
21:20	rata_	hmmm strange I don't get that
21:20	rata_	perhaps an slime thing, but I don't think so
21:22	rata_	aha... I have tried with something like (a/b) but not (a.b/c)
21:22	gfrlog	,(a/b)
21:22	clojurebot	java.lang.Exception: No such namespace: a
21:22	gfrlog	yeah
21:22	gfrlog	I get results based on that too
21:23	rata_	so I think the problem is the namespace, not the var
21:25	gfrlog	,(clojure.core/rata_)
21:25	clojurebot	java.lang.Exception: No such var: clojure.core/rata_
21:25	gfrlog	so you think that would compile?
21:26	gfrlog	(but not eval of course)
21:26	rata_	no, but that gives another error
21:26	rata_	java.lang.Exception
21:26	gfrlog	even at compilation?
21:27	rata_	yes
21:28	rata_	I have just compiled it and gave me that error
21:28	gfrlog	this is an interesting contrast to other dynamic languages
21:28	gfrlog	ruby will let you call whatever made up function you want and doesn't object until it executes
21:29	rata_	perhaps the solution is (refer ...)
21:29	rata_	have you tried that?
21:29	rata_	(refer your.ns)
21:29	gfrlog	,(doc refer)
21:29	clojurebot	"([ns-sym & filters]); refers to all public vars of ns, subject to filters. filters can include at most one each of: :exclude list-of-symbols :only list-of-symbols :rename map-of-fromsymbol-tosymbol ...
21:30	gfrlog	,(refer rata.gfrlog)
21:30	clojurebot	java.lang.ClassNotFoundException: rata.gfrlog
21:30	gfrlog	so I'd probably get that?
21:31	rata_	yes =(
21:31	rata_	,(doc load-string)
21:31	clojurebot	DENIED
21:33	rata_	I'm reading here http://clojure.org/Namespaces
21:33	rata_	,(resolve a.b)
21:33	clojurebot	java.lang.ClassNotFoundException: a.b
21:34	rata_	,(create-ns a.b)
21:34	clojurebot	java.lang.ClassNotFoundException: a.b
21:34	rata_	,(create-ns 'a.b)
21:34	clojurebot	#<Namespace a.b>
21:34	rata_	haaa
21:34	rata_	,(resolve 'a.b)
21:34	clojurebot	java.lang.ClassNotFoundException: a.b
21:34	gfrlog	clojurebot probably resets state every time
21:35	rata_	yes... just checking if the absence of the quote was significant before
21:35	rata_	gfrlog: try (create-ns 'your.ns)
21:36	gfrlog	okay
21:39	gfrlog	rata_: still get the classNotFoundException
21:39	gfrlog	yes, am quoting the ns name in create-ns
21:40	rata_	and you get the exception at the create-ns line or at the other line?
21:40	gfrlog	the other line
21:40	gfrlog	after create-ns
21:43	rata_	mmmm strange... I don't get that
21:43	rata_	(do (create-ns 'b.c) (b.c/a)) works for me
21:43	rata_	*compiles for me
21:43	gfrlog	maybe slime is "ruby mode"
21:44	rata_	hahaha could be
21:44	gfrlog	clojure: everything is dynamic at runtime, unless you do anything the normal way
21:46	rata_	load-string isn't at all normal I think
21:46	gfrlog	nope
21:46	gfrlog	but calling functions using symbols literals is
21:47	rata_	gfrlog: putting (create-ns a.b) (a.b/c) in a file and then executing that from the command line gives me a java.lang.Exception, not the ClassNotFoundException
21:47	rata_	the problem here is load-string
21:47	gfrlog	but the error happens before I ever use load-string
21:49	rata_	what?? then why are you calling something you haven't loaded yet?
21:50	gfrlog	the code doesn't get executed until the lib is loaded
21:50	gfrlog	but the code offends the compiler before the lib is loaded
21:52	gfrlog	(defmacro lenient-compiler [& forms] `(eval (do ~@forms)))
21:52	gfrlog	whoops
21:52	gfrlog	(defmacro lenient-compiler [& forms] `(eval '(do ~@forms)))
21:52	gfrlog	there we go
21:52	rata_	and did you put the create-ns thing before the offending code?
21:52	gfrlog	yes I did
21:52	gfrlog	you can imagine why it wouldn't make a difference:
21:53	gfrlog	the compiler doesn't execute create-ns
21:53	gfrlog	so it doesn't know whether or not it will actually result in the relevant namespace being created
21:53	gfrlog	all it knows is it still hasn't heard of that namespace
21:54	rata_	mmmm but for some reason when I execute (create-ns 'a.b) (a.b/c) it doesn't say anymore ClassNotFound
21:55	gfrlog	what context are you executing them in?
21:55	rata_	did you put it at the beginning of the file, after the ns macro?
21:55	gfrlog	no, just before the relevant statement
21:55	rata_	that's the whole file (create-ns 'a.b) (a.b/c)
21:55	gfrlog	does the second line in isolation still throw an error?
21:55	rata_	vim asdf.clj, put that, then execute
21:55	gfrlog	how do I "execute" it?
21:56	gfrlog	should I still call it asdf.clj if I use a dvorak keyboard?
21:56	rata_	java -cp clojure.jar clojure.main asdf.clj
21:57	rata_	gfrlog: yes, asdf is a beautiful combination of letters =P
21:57	rata_	when I put the second line alone it gives a ClassNotFoundException
21:57	gfrlog	lesse
21:57	gfrlog	lesee
21:57	gfrlog	let's see
21:58	gfrlog	so I get "no such var" -- which is what you get too?
22:00	rata_	yes
22:00	gfrlog	clojure is weird.
22:02	gfrlog	clojurebot: were you developed in a hammock?
22:02	clojurebot	Pardon?
22:10	rata_	gfrlog: well... a little step, but too little I think
22:10	gfrlog	what step?
22:11	rata_	to get a "no such var" instead of a ClassNotFound
22:11	gfrlog	well presumably the "no such var" is a runtime error rather than compile time
22:11	gfrlog	so in my context it wouldn't get thrown, since by runtime the var actually would exist
22:11	rata_	then try it
22:11	gfrlog	well I did and it doesn't compile
22:11	gfrlog	that's the whole weird thing about it
22:12	rata_	=(
22:12	rata_	yes weird
22:12	gfrlog	try executing your file with a (ns) at the top
22:12	gfrlog	for a different ns
22:12	rata_	ok
22:13	rata_	no such var
22:14	gfrlog	then add (load-string "(ns a.b) (defn c [] nil)") on the second line
22:24	rata_	gfrlog: works fine =)
22:24	gfrlog	clojure-version?
22:24	gfrlog	wait that shouldn't matter
22:24	rata_	1.2
22:24	gfrlog	me too
22:25	rata_	but it works without create-ns too
22:25	gfrlog	ah
22:25	gfrlog	so we're all confused now
22:26	gfrlog	I think clojure probably has about 7 different ways it can execute your code
22:27	rata_	no... the thing is when you load-string, the namespace becomes available
22:27	rata_	and the var too
22:27	gfrlog	oooh I know
22:27	gfrlog	put both the load-string and the (a.b/c) in separate functions
22:28	gfrlog	then after they've both been defined, call them in order
22:28	rata_	for example (ns d) (load-string "(ns a.b) (declare c)") (defn e [] (a.b/c)) (load-string "(ns a.b) (defn c [] nil)") (e)
22:28	rata_	works
22:29	gfrlog	what about without the first load-string?
22:30	rata_	it doesn't compile... that load-string is required
22:32	gfrlog	that's strange
22:33	gfrlog	I guess the statements are executed in some sense
22:33	rata_	yeah
22:33	gfrlog	if you delayed execution of the load-string statement until after (defn e...) had been processed, it probably wouldn't work
22:34	gfrlog	anyhow, I gotta drop out for the night
22:34	gfrlog	thx for the sleuthin
22:34	rata_	ok
22:34	rata_	good night
22:53	mreynolds	More newbism : I'm trying to create a configuration file for my app, but I like the idea of having it be code (a la, most of the time it's convention, but if I need to, I can write an anonymous function). I've looked at leiningen's implementation and it seems... hard due to the limitations of load-file. Is there a better/simpler way of doing this? I'm about to start down the road of building a DSL, but that seems complex as wel
22:54	brehaut	the simplest way is just to have a settings namespace
22:55	brehaut	if it doesnt need to be reloaded while the program is running its by far the easiest
22:55	mreynolds	brehaut: It doesn't. Can you give me more details for that? Is that just a matter of me including a namespace that is defined separately?
22:56	brehaut	yeah its just like any other clojure file in your project
22:56	brehaut	i have as myproject.settings
22:56	brehaut	and i def the settings to be clojure structures
22:56	mreynolds	brehaut: Ahh, heh. I've yet to actually use more than one ns (still learning). I'll dork around with that. Thanks!
23:34	chouser	wow, lazy-test's failure reports are so much nicer than clojure.test's.
23:35	chouser	sexpbot: tell stuartsierra