#clojure – 2010-02-20

2010-02-20

03:21	LauJensen	Morning team
03:41	wooby	hi LauJensen
04:08	Hali_303	why is this false? (contains? [:p] :p)
04:12	Hali_303	never mind, I should read the docs instead :D
06:56	raek	,(contains? [:p] :p)
06:56	clojurebot	false
06:56	Chousuke	clojurebot: contains?
06:56	clojurebot	contains? is for checking whether a collection has a value for a given key. If you want to find out whether a value exists in a Collection (in linear time!), use the java method .contains
06:57	raek	Hali_303: contains? only works for maps and sets...
06:57	Chousuke	no, it works for vectors too
06:57	Chousuke	(doc contains?)
06:57	clojurebot	"([coll key]); Returns true if key is present in the given collection, otherwise returns false. Note that for numerically indexed collections like vectors and Java arrays, this tests if the numeric key is within the range of indexes. 'contains?' operates constant or logarithmic time; it will not perform a linear search for a value. See also 'some'."
06:57	Chousuke	,(contains? '[a b c] 2)
06:57	clojurebot	true
06:57	kotarak	raek: no linear search, for vectors it tests whether the index is contained
06:57	raek	ah, yes...
06:57	Hali_303	thanks guys! i'm still learning clojure :)
06:58	raek	of course, the indices are the keys of the vector
06:58	Hali_303	what are you using for web development? does anyone use compojure for some real production apps?
07:07	raek	I'm using compojure, but not for a "production" project... :)
07:08	raek	at most, about 20 persons will use it
07:11	Hali_303	raek: are there some example projects on the web using compojure? I'd be interested how to do authentication and validation
07:27	raek	Hali_303: no, I'm sorry. I've only used compojure for two weeks
07:27	Hali_303	raek: no problem, I'll keep searching
07:28	raek	authentication sounds like something that should be fairly easy to be done in middleware
08:20	avarus	hi
11:49	rrc7cz-hm	how might you go about converting "a__b__c" = 1, "d" = 2 into {:a {:b {:c 1}} :d 2}?
11:49	rrc7cz-hm	where some delimiter signals a nesting level
11:54	kotarak	,(apply merge (for [[k v] (partition 2 ["a_b_c" 1 "d" 2])] (let [ks (.split k "_")] (assoc-in {} ks v))))
11:54	clojurebot	{"d" 2, "a" {"b" {"c" 1}}}
11:54	kotarak	,(apply merge (for [[k v] (partition 2 ["a_b_c" 1 "d" 2])] (let [ks (map keyword (.split k "_"))] (assoc-in {} ks v))))
11:54	clojurebot	{:d 2, :a {:b {:c 1}}}
11:56	rrc7cz-hm	wow
11:56	kotarak	rrc7cz-hm: has some gotchas though.
11:57	kotarak	,(apply merge (for [[k v] (partition 2 ["a_b_c" 1 "d" 2 "a" :boooo])] (let [ks (map keyword (.split k "_"))] (assoc-in {} ks v))))
11:57	clojurebot	{:d 2, :a :boooo}
11:58	rrc7cz-hm	kotarak: unfortunately I'll be iterating over a seq of key-val pairs which could appear in any order. I guess the last one would override all previous then
11:59	kotarak	rrc7cz-hm: yes, you have to merge the different levels.
11:59	kotarak	rrc7cz-hm: that makes things more complicated.
12:00	rrc7cz-hm	kotarak: thanks for the start though; this is a good base to build on
12:02	kotarak	,(reduce (fn [m [k v]] (let [ks (map keyword (.split k "_"))] (assoc-in m ks v))) {} (partition 2 ["a_b_c" 1 "d" 2 "a_f" 3]))
12:02	clojurebot	{:d 2, :a {:f 3, :b {:c 1}}}
12:03	kotarak	rrc7cz-hm: maybe this (^^^^) is more what you need?
12:04	rrc7cz-hm	kotarak: that's exactly it
12:04	rrc7cz-hm	basically I have nested maps that I convert to flat maps with __ deliminating levels. this is so I can put the map in an html form
12:05	kotarak	rrc7cz-hm: I hope you don't trust this data when you get it back...
12:05	rrc7cz-hm	so there are inputs like <input type="text" name="a_f_s" value="1" />
12:05	rrc7cz-hm	kotarak: what do you mean?
12:06	kotarak	rrc7cz-hm: Naa. It's ok. My fear was you want to carry state with that.
12:06	kotarak	rrc7cz-hm: in a hidden field or so.
12:06	rrc7cz-hm	kotarak: it's for selecting product options, which can get quite complex. Right now I have the nested maps converted to the flat one just fine
12:07	rrc7cz-hm	kotarak: I'm trying to now convert it back for comparison
12:07	kotarak	rrc7cz-hm: that's a nice application actually. :)
12:07	rrc7cz-hm	kotarak: I will then walk the various product configurations (nested maps) and try to find the best match from what I got from the UI
12:08	rrc7cz-hm	kotarak: yeah, it's the only way I've been able to think of for handling arbitrarily complex product customizations
13:14	hamza	does future objects use a thread pool or each one fires up a new thread?
13:16	{newbie}	future object have to me "executed" by an external source
13:16	{newbie}	like and Executor
13:16	{newbie}	s/and/an
13:18	hamza	kk thanks.
14:02	jlilly	is there a shortcut for (def myvar (inc myvar)) ?
14:03	AWizzArd	No, because this should not be done within programs. Clojure is dynamic - this is only allowed for administration purposes.
14:03	jlilly	trying to preserve state for the length of a loop
14:04	jlilly	ie: determining an outcome based on a nested if statement.
14:04	AWizzArd	In a loop you can have your own flags/counters
14:04	AWizzArd	You can modify them with recur
14:04	Chousuke	defs anywhere but on the top level usually means you have non-idiomatic code
14:04	Chousuke	and that you need to restructure it.
14:04	Chousuke	but how, is difficult to tell until I can see the code in question :)
14:05	kotarak	,(loop [x 1] (if (= x 5) :done (recur (inc x)))
14:05	clojurebot	EOF while reading
14:05	kotarak	,(loop [x 1] (if (= x 5) :done (recur (inc x))))
14:05	clojurebot	:done
14:05	jlilly	http://pastie.org/834439
14:07	Chousuke	hmm
14:08	jlilly	so my first inclination is to make it (def robot1-wins (inc robot1-wins))
14:08	jlilly	but I understand that's a bad idea.
14:09	jlilly	perhaps I really want to pull out the "who won" if block into a function
14:13	Chousuke	hmm
14:17	mattrepl	are protocols and datatypes expected to change much now?
14:18	Chousuke	jlilly: http://gist.github.com/309849
14:20	Chousuke	jlilly: rather than explicit loops, generating a sequence of the stuff you want to process is often easier :)
14:20	Chousuke	jlilly: in the gist, I generate an infinite sequence of battle results and then take 50 of them
14:21	Chousuke	jlilly: next, it's reduced to a triple containing r1-wins, r2-wins and ties
14:23	Chousuke	jlilly: the (or winner :neither) thing in condp is just there in case winner is nil (which won't be the case here, but I put it there regardless)
14:26	Chousuke	mattrepl: I think they're pretty close to their final form, but since they're not in a release yet, they might change.
14:26	mattrepl	Chousuke: thanks
14:28	maravillas	how might i destructure a list of arguments to pass to a java constructor? that is, something along the lines of (apply new JCheckBox args), if "new" were a function, but...
14:28	Chousuke	maravillas: you can't do that
14:29	Chousuke	maravillas: but you can do (let [[a b c] args] (JCheckBox. a b c)) :)
14:29	maravillas	ah, darn. ii wanted to be able to handle multiple constructor overloads with one statement
14:30	Chousuke	That's unfortunately not possible. :)
14:30	maravillas	oh well. thanks :)
16:16	{newbie}	has anyone here used clojure for numerical algorithms?
16:47	ugglan	gnight
17:09	jlilly	Chousuke: thanks for that gist. Makes things much nicer. :)
17:54	{newbie}	hi! was the 1.1.x brach of clojure contrib already release?
17:54	{newbie}	ed*
18:02	Chousuke	{newbie}: yes. though I'm not sure where to download it :P
18:03	{newbie}	from github?
18:03	AWizzArd	You can download Clojure from http://build.clojure.org/ too.
18:07	{newbie}	AWizzArd: are these versions compiled against each other?
18:07	AWizzArd	Yes.
18:08	{newbie}	nice! thanks
18:16	jcromartie	o hai
18:16	jcromartie	Is there a more idiomatic way to do this: (assoc response :body (json-str (:body response))) ?
18:16	jcromartie	basically to alter a hash
19:01	dermatthias	.
19:04	tomoj	hmm, it seems like amap for dot products on float arrays is slower than map on lazy seqs
19:12	chouser	whoa
19:14	AWizzArd	That would be surprising.
19:22	tomoj	I probably screwed up, then
20:58	hamza	gents, can someone tell me why this does not work, http://paste.lisp.org/display/95334 ?
21:01	somnium	hamza: I think the namespace created by 'create-ns is completely empty (ie lacking clojure.core)
21:03	hamza	any way to import definitions from clojure.core?
21:03	somnium	,(doc refer)
21:03	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 For each public interned var in the namespace named by the symbol, adds a mapping from the name of the var to the var to the current namespace. Throws an exception if name is already mapped to something else in the current name
21:04	scgilardi	but you'll have to fully qualify it: (clojure.core/refer 'clojure.core)
21:05	hamza	thanks alot that solved it..
21:20	zab	Hi. I'm trying to upload a very simple Clojure app to App Engine. Once uploaded, I keep getting this stack trace: http://pastebin.com/dabf3cd9
21:20	zab	points to clojure.lang.DynamicClassLoader?
21:20	zab	Seems like GAE's sandbox doesn't like it? java.security.AccessControlException
21:26	somnium	zab: I think compojure.http.multipart disagrees with AE's security policy
21:26	zab	somnium: Yeah I've already commented it out of Compojure sources, and recompiled
21:29	somnium	or you can do (:use [compojure.http :exclude [multipart]]), still getting the error after excluding?
21:32	zab	hmm I deleted src/compojure/http/multipart.clj, commented it out, recompiled and deployed. Same exception raised.
21:32	zab	stack trace also shows it rising from clojure and not compojure though?
21:33	somnium	there might be others, are you doing (:use compojure) in the ns?
21:33	zab	yeah
21:33	zab	(:use compojure.http compojure.html)
21:35	zab	oh, no longer getting that exception. Now getting java.lang.NoClassDefFoundError for my servlet class.
21:41	somnium	zab: dunno, last time I used it with sdk 1.3 this stub was working: http://paste.pocoo.org/show/180670/
22:25	slyphon	is it possible to deref inside a destructuring ?
22:25	slyphon	oh, hrm, that probably doesn't make sense
22:31	tomoj	you can deref to get the thing you're destructuring..
22:32	slyphon	i'm destructuring a nested hash-map like structure
22:32	tomoj	the leaves are refs?
22:32	slyphon	yeah
22:32	slyphon	well, one of the branches is a ref
22:32	tomoj	don't think you can do that, then
22:33	slyphon	i may be overdoing it with the refs
22:33	slyphon	yeah
22:33	slyphon	it probably is more sensible to do it inside a let in a dosync
22:40	slyphon	can you mix the :keys form with the symbol/keyword forms? like (let [{:keys [a b c] foo :foo} thing] ...)
22:41	slyphon	hrm
22:42	slyphon	oh, duh
22:44	zab	oh man, I tried everything to get a Compojure app running on GAE. This was with the latest 1.3.1 GAE SDK. Nothing worked.
22:44	zab	Then I downgraded the SDK to 1.2.1 (the last one that I could find), and now everything is working.
22:49	zab	Okay I retract everything I said. 1.3.1 is now working. Problem was I was not copying across lib/appengine-tools-api.jar
22:49	zab	Seems it's necessary for it to work in deployment, but not for the dev server.
23:13	Crowbar7	Evening
23:47	sdm	Hi, I'm just starting to learn clojure ... is it possible to do a loop or dotimes inside of a doto?
23:48	sdm	(doto (String.) (dotimes [i 10] (.concat i))) => #<CompilerException java.lang.IllegalArgumentException: dotimes requires a vector for its binding (REPL:1)>
23:48	sdm	am I doing something crazy?
23:49	somnium	,(macroexpand-1 '(doto (String.) (dotimes [i 10] ...)))
23:49	clojurebot	java.lang.RuntimeException: java.lang.IllegalArgumentException: dotimes requires a vector for its binding
23:50	somnium	sdm, hmm, not sure why he choked
23:50	hamza	you can't, it will mess dotimes
23:51	hamza	(clojure.core/let [G__27 (String.)] (dotimes G__27 [i 10] ...) G__27)
23:52	sdm	Okay... so doto and dotimes (or loop) collide the binds?
23:54	hamza	when in a doto block every function used will be supplied x in its first argument, so not just dotimes it may mess a bunch of things.
23:56	sdm	ahh I see, I thought doto did something only functions starting with . (like (.concat ...) that makes sense
23:56	sdm	thank you!
23:56	hamza	np
23:57	Crowbar7	So, I'm quite new to Clojure and was wondering a couple of things. I'm building a really fairly crappy IRC bot that makes a thread whenever a trigger is caught. writing an re-find for everyone one in a cond seems a little lengthy. Would it be possible to just have the keywords checked in a map then using the functions names tied to the keyword to spawn the thread? Or am I doing this whole thing absolutly horrible?
23:58	Crowbar7	The reason for threading is proof of concept / fun and because I hate it when http scraping bots hang because they are still collecting data ro something and I can't query them.