#clojure – 2010-08-01

2010-08-01

00:04	defn	apparently i still suck at using zip-filter.xml/xml->
00:05	defn	(def rss (zip/xml-zip (xml/parse ("url string))))
00:07	defn	bah maybe i got it...
00:09	rhudson	defn: I'd be interested in seeing your solution. I haven't played with zippers much, and zip-filter not at all
00:13	technomancy	defn: rudel is great if you're just sharing a buffer or two
00:14	technomancy	defn: but usually when pairing you want to share the whole frame; tmux is way better for that
01:17	technomancy	http://www.everytopicintheuniverseexceptchickens.com/
01:17	technomancy	good night, Internet.
01:18	lancepantz_	good night
02:21	notsonerdysunny	can I findout the version of clojure.jar from the repl?
02:21	brehaut	,clojure-version
02:21	clojurebot	{:interim true, :major 1, :minor 2, :incremental 0, :qualifier "master"}
02:26	notsonerdysunny	thanks brehaut
02:26	brehaut	no worries
02:36	mister_m	what exactly is the emacs starter kit?
02:37	mister_m	and does anyone know if I can run the clojure repl as an inferior emacs process?
02:37	brehaut	mister_m: its a set of .emacs stuff that gives you a well rounded initial set up with (i believe) a focus towards dynamic languages
02:38	notsonerdysunny	is the function "source" new in 1.2 or was it always there?
02:38	brehaut	been there since at least 1.1
02:38	notsonerdysunny	hmm
02:40	brehaut	at least, i recall using it prior to last week
02:40	brehaut	and i only upgraded to 1.2 last week
02:40	brehaut	http://clojuredocs.org/v/2445 tells me it was added in 1.0
02:42	brehaut	though it might have migrated from contrib?
02:58	defn	mister_m: as far as an inferior process, you mean slime?
02:58	defn	mister_m: this might be helpful to you:
02:59	defn	http://gist.github.com/407543
03:02	mister_m	defn, with any luck I can get that working
03:02	flintf	mister_m swank_clojure is available as an emacs package, very easy to get started with
03:04	flintf	you just need to install ELPA then, the relevent packages in EMACS
03:09	defn	that's my recommendation
03:09	defn	"but don't take /my word for it/." -Levar Burton
03:12	mister_m	I'm new to emacs, but I'll see if I can't work it out
05:16	Bahman	Hi all!
05:27	defn	hey Bahman
05:27	edbond	how force / to remove double, not ratio?
07:55	kiemdoder	has clojure/contrib/repl_utils.clj been dropped in 1.2?
07:55	kiemdoder	or moved rather
08:38	raek	http://github.com/clojure/clojure-contrib/blob/master/src/main/clojure/clojure/contrib/repl_utils.clj
08:38	raek	seems to be there
09:04	Bahman	Hi all!
09:43	Bjering	Two questions, #1: this gives me null-pointer-exception, why? #2 : am I using refs all wrong, how should I think about this problem?
09:43	Bjering	https://gist.github.com/1d2bde05e5a923154661
09:46	pastorn	hello
09:46	pastorn	ok, so i'm messing in scheme, but this should apply here as well ;)
09:46	pastorn	i have
09:46	pastorn	(define xs (+ 10 5 1)) but i want with nifty usage of cdr and apply calculate (- 10 5 1)
09:46	pastorn	is this possible?
09:49	pastorn	silly me... it had to be (define xs '(+ 10 5 1))
09:53	fyuryu	pastorn: (eval (cons '- (next '(+ 10 5 1))))
09:54	fyuryu	pastorn: or better (apply - (next '(+ 10 5 1)))
09:54	pastorn	is next something clojure-specific?
09:54	pastorn	oh, it's cdr
09:54	fyuryu	yes
09:54	fyuryu	I think it's cdr in scheme
09:55	Bjering	fyuryu: Do you have any clue what is wrong with my paste above?
09:56	pastorn	Can you run clojure code on android devices?
10:01	defn	http://www.mail-archive.com/clojure@googlegroups.com/msg07499.html
10:01	raek	car=first, cdr=rest/next
10:02	defn	raek: is that accurate to say cdr works like both rest and next?
10:02	raek	next always return nil if there are no more elements
10:02	raek	well, clojure has a distinction that neither CL or Scheme have
10:02	defn	pastorn: http://riddell.us/ClojureAndAndroidWithEmacsOnUbuntu.html
10:03	pastorn	defn: emacs? who uses that?
10:03	defn	people who write code
10:04	pastorn	bah...
10:04	pastorn	vi vi vi - the editor of the beast
10:04	defn	save your editor wars for another day, friend
10:04	pastorn	haha
10:04	defn	goal: to write code that works
10:04	mfex	Bjering, alter and commute follow the pattern (alter ref fn & args), so write (alter users conj {new-map})
10:05	raek	can't find the article about clojure editor usages
10:05	raek	I saw a piechart on that once
10:05	defn	it was from rubylearning
10:05	defn	but it doesn't matter
10:06	defn	it's quite fragmented. people use what they use. it doesn't matter.
10:06	defn	(although personally i dont think vim has anything comparable to slime)
10:06	defn	((nor does any other editor for that matter))
10:06	raek	ah, here it is: http://muckandbrass.com/web/display/~cemerick/2010/06/07/Results+from+the+State+of+Clojure%2C+Summer+2010+Survey
10:06	pastorn	defn: slime? you have a link?
10:07	raek	http://muckandbrass.com/web/download/temp/chart2996995522313431103.png
10:07	defn	http://common-lisp.net/project/slime/
10:07	raek	pastorn: http://github.com/technomancy/swank-clojure
10:07	raek	slime is an emacs thing that lets you connect to a swank server
10:07	raek	swank-clojure is a swank server for clojure
10:08	pastorn	cool stuff :)
10:08	defn	it's more than that really raek
10:08	raek	so, swank is the part that is clojure-specific
10:08	raek	ok, but simplified
10:08	defn	yeah fair enough
10:08	Bjering	mfex: Thank you! as to my #2, is it good style? Or should I use 3 different refs inside users instead?
10:09	raek	anyway, the clojure-specifics are documented at technomancy's swank-clojure
10:09	defn	well, some of them
10:09	defn	there are plenty of things undocumented in swank-clojure that slime does by virtue of the bridge that swank clojure creates
10:09	defn	like M-. for instance
10:09	raek	and C-M-x I guess
10:10	defn	C-x C-e
10:10	defn	etc.
10:10	raek	but with C-x C-e, you have to put the point at the end of the form to eval, right?
10:11	mfex	Bjering, for #2 I have no ideas or experience
10:11	defn	yeah but that's still part of slime more than it is a swank-clojure feature
10:11	defn	that's just a fancy slime eval
10:11	raek	hrm, ok. I remembered seeing C-x C-e in the readme but not C-M-x
10:13	defn	yeah i dont know all the features tbqh
10:13	defn	i just think it's worth mentioning that slime does a lot of automatic stuff by virtue of the bridge
10:13	sid3k	anyone knows what "no message" error is/
10:13	defn	that is not explicitly stated in the bridge (swank-clojure) documentation
10:14	Bjering	Rephrased question, what is the preferable way todo this, A or B? https://gist.github.com/7f8962c6e77d8784b296
10:14	defn	B
10:15	sid3k	http://paste.lisp.org/display/113042
10:15	sid3k	this example raises "no message" exception, I couldn't understand the reason
10:16	Bjering	defn: Thank you, may I further ask why? :)
10:17	defn	Bjering: i dont have a very good reason
10:17	raek	Bjering: unless the parts change independently and very often, I would say B
10:17	defn	:D
10:18	defn	Bjering: yeah, B just looks like it will be more performant
10:18	defn	no need for the triple ref
10:18	defn	also you might consider making :next-id an atom
10:18	raek	in the first case, would have to "asseble" a map with the three associations if you would need it as a single value
10:19	raek	a rule of thumb might be don't put in more refs than you need
10:22	defn	Bjering: you raise an interesting question though, but like most things, it requires you explain exactly what you're trying to do
10:22	raek	if a transaction restart and you use atoms for next-id, you might get "gaps" in the numbering
10:22	kiemdoder	reak: thanks for the reply about clojure-contrib. I'm trying clojure for the first time and is working through some example and did not realise that clojure-contrib is actualy a separate project.
10:23	raek	if that is acceptable, then using atoms won't make transactions restart because two of them wanted a new id at the same time
10:23	Bjering	defn: A typical data-table with auto-increment IDs and index on both names and id, in RAM, transactional.
10:25	defn	Bjering: would an atom for next-id be out of the question?
10:25	kiemdoder	oops raek, got you name wrong :-0
10:25	defn	Bjering: how will you be accessing the data? like could you give an example of your total structure?
10:27	defn	Bjering: your version A looks better in the create-user code, but B looks better in the ref creation code
10:27	defn	and vice versa
10:27	Bjering	not out of the question, but strictly sequential (without gaps) is kind of nice when debugging I guess. Performance isn't critical for this particular scenario (but nice to learn you reasoning nevertheless), what I care about is correctness, readability, "conceptual clarity" and learning to be idiomatic in clojure.
10:28	defn	if we're talking conceptual clarity then i greatly prefer A after looking at it for a bit longer
10:28	Bjering	So, A until profiler says otherwise?
10:28	defn	im not the end-all be-all of clojure idioms here, so take my advice with a grain of salt
10:29	defn	but A just seems a lot more clear to me
10:29	defn	I like the @(users :next-id)
10:30	raek	hrm, when looking closer to that case, I'm starting to lean towards A, too
10:30	defn	yeah :\
10:31	defn	it's a weird case -- i disagree with the multiple refs to represent what are essentially values in a hashmap
10:31	raek	an insert operation would alter next-id and commute-in the new row
10:31	defn	but there is no doubt that the dosync...alter feels more clojurish
10:32	raek	anyway, don't use a ref for every field for every row in the table :)
10:33	defn	it would seem that there will be more contention with A
10:33	raek	I started to make a db layer in one of my projects: http://github.com/raek/konserver/blob/master/src/konserver/db.clj
10:33	defn	does that seem like a fair guess?
10:33	raek	that file only contains the functional part, though
10:34	raek	outside it, I used one ref for each table, and one ref for each auto-increment counter (for those tables that needed it)
10:36	Bjering	Usage is a very benchmark/prototype chat-like server. I am evaluating using Clojure for a 2d Strategy MMO-server (not twitch-based). Want to see how much complexety I get rid of comparted to a C++ boost::asio solution, and how much users per shard I give up.
10:36	Bjering	very simple I meant to write...
10:37	raek	one very great thing you get with clojure: being able to do snapshots of the world, while it's still living
10:37	raek	you won't have to pause the game 1h every day to store the state to disk
10:37	Bjering	yes, many things are awesome, I just want to learn the price of awesome before I embark 100% :)
10:37	raek	sure
10:38	raek	I have a friend who's considering implementing a Ultime Online server in clojure
10:39	raek	those problems he experienced with a C# based implementation is what clojure was made to solve
10:39	defn	no way
10:39	Bjering	raek: Has he settled on a network-lib? I am going to try this with Netty, from browsing the net alone it seems the best.
10:39	defn	ultima online?
10:39	defn	that takes me back
10:39	defn	wayyyyy back
10:39	raek	he is serp_, btw
10:40	defn	i wasted like 3 of my most formative years learning german on Ultima Online
10:40	defn	by playing a euroshard
10:40	raek	Bjering: you might be interested in aleph
10:41	raek	hrm, is Netty a http server or a general server?
10:41	defn	there's a ring adapter for netty
10:41	raek	or simply a asynchronous-anything lib?
10:41	Bjering	I wasnt planning on using http, I need push, I'll be using google protobufs over binary sockets I think. My client will be Flash.
10:42	raek	ok, aleph is a http server
10:44	raek	Bjering: I don't think he has settled with any lib yet
10:45	Bjering	But I run ahead of myself, for this test, I will use simple strings and it is just a chat :) To learn what #users I can reach with that, and how it hits the wall. My C++ impl was CPU bound and that scares me a little. But it was also getting complex so I might have done something seriosly wrong in it.
10:46	Bjering	And as you understand of my earlier questions, learning clojure along the way :)
10:47	raek	I hope I haven't confused you too much... :)
10:48	defn	for a chat impl I choose B
10:48	defn	..maybe.. lol
10:50	Bjering	Haha, I'll write the whole thing and put the source somewhere and then post the question again. Seems there is more to learn here.
10:51	Bjering	I'll start with A though, it read easier to me. Thanks for the input.
10:52	defn	Bjering: would you mind if i wrote a post about your example?
10:52	defn	id like to work on it later today and do some timing
10:53	Bjering	Not at all, especially if you post to me here if you learn anything interesting :)
11:07	pdk	,(defmulti populate [chain content] (if (zero? 0) ::zero :: one))
11:07	clojurebot	Invalid token: ::
11:07	pdk	,(defmulti populate [chain content] (if (zero? 0) ::zero ::one))
11:07	clojurebot	java.lang.Exception: The syntax for defmulti has changed. Example: (defmulti name dispatch-fn :default dispatch-value)
11:08	defn	Bjering: ill look at it later and ping you when i come to a thoughtful position :)
11:08	defn	ciao all
11:08	pdk	ok so what's wrong with this defmulti code here
11:09	Bjering	defn: Great, I'll shift to a more Sunday-appropriate problem of trying to get Starcraft 2 to play without burning up my GPU now.
11:09	defn	Bjering: haha! im in the process of downloading
11:09	defn	maybe when i wake up it will be finished
11:09	defn	"5 hours remaining"
11:09	defn	anyway, night all
11:09	pdk	,(defmulti populate (fn [chain content] (if (zero? 0) ::zero ::one)))
11:09	clojurebot	DENIED
11:20	slyrus	grumble grumble
11:20	slyrus	java.lang.OutOfMemoryError: PermGen space (smiles2.clj:9)
11:20	slyrus	again :(
11:34	Lajla	Clojure doesn't support using the continuation passing style, does it?
11:35	qbg	You could do it, if you really wanted to
11:37	Zeiris	Is learning Clojure likely to get me a job? :)
11:40	Chousuke	Zeiris: If you learn it well enough, it might.
11:43	sid3k	I don't get the function named "reduce", is there any easy tutorial or sth. explaining it?
11:44	qbg	(reduce + [1 2 3]) == (+ (+ 1 2) 3)
11:44	Chousuke	well, it reduces a collection of values into a single scalar value
11:46	Chousuke	there's not really much to explain. you have a collection of values of type A, a function that takes two values of type A and returns a value of type A. then you apply the function to your initial value and the first item in the collection, then again to the result of that and the second item in the collection, et cetera until you run out of values in the collection
11:46	sid3k	thanks, I guess I need to learn how problems can be solved using this function
11:47	qbg	reduce is essentially an accumulator
11:47	Chousuke	though clojure being dynamic "type A" here means "whatever works" :P
11:47	qbg	You can alternatively see it a state machine
11:48	qbg	Where the fn takes in the old state and the input and returns the new state
11:48	qbg	And the function returns the final state
11:48	sid3k	I've coded a little thing: (reduce #(str %1 %2) [\h \e \l \l \o])
11:49	Chousuke	sid3k: str already takes two arguments so the anonymous function is not necessary.
11:49	qbg	,(reduce #(str %1 %2) [])
11:49	clojurebot	java.lang.IllegalArgumentException: Wrong number of args (0) passed to: sandbox$eval501067$fn
11:50	qbg	,(reduce str [])
11:50	clojurebot	""
11:50	qbg	,(reduce #(str %1 %2) "" [])
11:50	clojurebot	""
11:50	sid3k	Chousuke: sure, I'm trying to find a killer usage example
11:51	qbg	,(reduce + (range 10))
11:51	clojurebot	45
11:51	Chousuke	sid3k: reduce is quite situational, so it's hard to think up examples that don't seem trivial
11:52	sid3k	,(apply + (range 10))
11:52	clojurebot	45
11:52	sid3k	when should we use reduce? is there any killer usage example?
11:52	qbg	(reduce conj () [1 2 3 4])
11:52	qbg	,(reduce conj () [1 2 3 4])
11:52	clojurebot	(4 3 2 1)
11:52	Chousuke	sid3k: but whenever you have a collection of values and you need to produce a single value (or a bunch of stats, for example) out of them, consider reduce
11:53	sid3k	all right
11:54	sid3k	tyvm
11:55	mfex	sid3k, what is called reduce is called fold in other functional programming languages, the first reference on the wikipedia page has a lot of examples
11:57	sid3k	mfex: you are right, thanks
11:59	raek	,(reduce (fn [freqs elem] (assoc freqs elem (inc (get freqs elem 0)))) {} [:a :a :b :c :a :b])
11:59	clojurebot	{:c 1, :b 2, :a 3}
12:00	raek	,(reduce (fn [freqs elem] (merge-with + freqs {elem 1})) {} [:a :a :b :c :a :b])
12:00	clojurebot	{:c 1, :b 2, :a 3}
12:00	sid3k	it's a very complicated example for a newbie like me :)
12:02	raek	the idea here was to count how many times each thing occurs in the vector
12:02	raek	from the beginning, there are no counts at all
12:02	raek	hence the empty map
12:02	raek	after the first element, the partial result is {:a 1}
12:03	raek	after the second, it has seen :a once more, so then it's {:a 2}
12:03	pdk	,(doc rest)
12:03	clojurebot	"([coll]); Returns a possibly empty seq of the items after the first. Calls seq on its argument."
12:03	pdk	,(doc drop)
12:03	clojurebot	"([n coll]); Returns a lazy sequence of all but the first n items in coll."
12:04	pdk	,(cons 1 '())
12:04	clojurebot	(1)
12:04	pdk	,(cons 1 nil)
12:04	clojurebot	(1)
12:06	sid3k	raek: thanks, I should check out docs of some functions in the example
12:06	sid3k	here is the example I've written using reduce:
12:06	sid3k	(defn factorial [number] (reduce * (reverse (range 1 (inc number)))))
12:06	pdk	(doc trampoline)
12:06	clojurebot	"([f] [f & args]); trampoline can be used to convert algorithms requiring mutual recursion without stack consumption. Calls f with supplied args, if any. If f returns a fn, calls that fn with no arguments, and continues to repeat, until the return value is not a fn, then returns that non-fn value. Note that if you want to return a fn as a final value, you must wrap it in some data structure and unpack it after trampoline r
12:06	qbg	sid3k: Why reverse it?
12:07	raek	sid3k: well, there you have your killer usage example :)
12:07	sid3k	qbg: I dunno what I thought
12:07	sid3k	raek: thanks :)
12:07	raek	reduce separates the iteration from what to do each step
12:08	sid3k	just like map and filter functions
12:08	raek	exactly :)
12:08	sid3k	tyvm
12:16	diracdelta	Hi, I've looked into clojure before, but the top google hit when I try to find information on they syntax of macros is the clojure macro page, which has a short example but no explanation of the syntax. Is the reference the source code, or is there a book which does a good job?
12:17	raek	some of it (mainly "syntax-quote", `) is documented on clojure.org/reader
12:17	qbg	There is the defmacro docstring
12:17	qbg	,(doc defmacro)
12:17	clojurebot	"([name doc-string? attr-map? [params] body] [name doc-string? attr-map? ([params] body) + attr-map?]); Like defn, but the resulting function name is declared as a macro and will be used as a macro by the compiler when it is called."
12:18	raek	but macros don't have to use syntax-quote
12:18	qbg	But that may not be too helpful
12:18	raek	macros are simply functions that get code as arguments and return code
12:19	raek	the syntax of macros themselves are the same as ordinary functions
12:19	raek	you can try the macro as if it was a function by using macroexpand-1
12:19	Chousuke	syntax-quote is just a convenient way to construct lists and vectors containing symbols, which is what most clojure code is.
12:20	diracdelta	Looking at /reader now, I think that is what I was looking for, thank you :)
12:20	raek	,(macroexpand-1 '(when some-cond do-foo do-bar))
12:20	clojurebot	(if some-cond (do do-foo do-bar))
12:20	Chousuke	,(@#'when 'some-cond '(doo foo bar)) you can also do this :P
12:20	clojurebot	java.lang.IllegalArgumentException: Wrong number of args (2) passed to: core$when
12:20	Chousuke	hmm
12:20	Chousuke	oh, right, they take the implicit args.
12:21	Chousuke	that used to work :P
12:22	raek	as Chousuke said, syntax-quote is not restricted to macros
12:23	Chousuke	,`(like this)
12:23	clojurebot	(sandbox/like sandbox/this)
12:24	raek	,(let [x 1, y 2, z [3 4 5]] `(~x ~y ~z ~@z))
12:24	clojurebot	(1 2 [3 4 5] 3 4 5)
13:06	slyrus	any idea why I can't seem to map name onto a record that implements clojure.lang.Named?
13:06	slyrus	http://gist.github.com/503538
13:14	raek	for some reason, it looks like it tries to call clojure.core/name on a map
13:14	raek	,(name {:a 1, :b 2)}
13:14	clojurebot	Unmatched delimiter: )
13:14	raek	,(name {:a 1, :b 2})
13:14	clojurebot	java.lang.ClassCastException: clojure.lang.PersistentArrayMap cannot be cast to clojure.lang.Named
13:14	raek	slyrus: do you have a protocol method called name?
13:24	slyrus	no, but I have clojure.lang.Named (getName [atm] _name))
13:24	slyrus	and a _name field
13:25	slyrus	I can understand why this might not work, but then why would (map name (first q)) work?
13:29	slyrus	oh, never mind...
13:30	slyrus	one of the elements was a vector containing a map, not an Atom.
13:30	slyrus	it would be nice if the slime debugger allowed me to inspect the stack
13:31	pdk	(doc every)
13:31	clojurebot	excusez-moi
13:31	pdk	you get the hell over here clojurebot
13:32	pdk	(doc every?)
13:32	clojurebot	"([pred coll]); Returns true if (pred x) is logical true for every x in coll, else false."
13:44	raek	slyrus: I've heard about a "debug-repl" project
13:48	sid3k	is "coll" a lisp/clojure/java term or a general computing term?
13:48	sid3k	I don't know what it means exactly but as I understand colls are a kind of sequences
13:49	raek	it's short for "collection" which is a very general term
13:49	raek	a collection is a collection of things, that's pretty much it
13:49	raek	in clojure, you can do seq on collections to get a sequence of its elements
13:50	raek	java has a java.util.Collection interface too: http://download-llnw.oracle.com/javase/6/docs/api/java/util/Collection.html
13:51	raek	most clojure functions that take a "coll" argument does (seq coll) and operate on that sequence
13:51	sid3k	raek: tyvm
13:53	LauJensen	Good morning gents (UGT)
13:53	raek	good morning! (UGT)
13:55	raek	I guess one could define "coll" as anything implementing Seqable, or anything else the seq function knows how to turn into a sequence (e.g. java.util.Collection and java arrays)
13:56	rhudson	and strings, which are then treated as char seqs
14:01	pdk	sid3d when you read the arglists for functions and stuff coll is short for collection
14:02	sid3k	another thing I don't get is the "lazy" term, I'm reading ociweb's great guide and I couldn't understand the lazy sequences part
14:02	pdk	basically anything that contains multiple items in it like a map, sequence whatever so they can be treated alike most of the time
14:02	pdk	hm where is the ociweb guide
14:02	sid3k	here: http://java.ociweb.com/mark/clojure/article.html
14:03	pdk	the idea with lazy evaluation is to let you do things like generate an infinite sequence of items in a finite amount of space in a way that's still idiomatic for the language
14:03	pdk	so if i had a function that gave me an infinite sequence of (0 1 2 3 ...)
14:04	pdk	plain jane non-lazy version would try to generate and return this whole sequence at once and obv would crash and burn
14:04	raek	you could wrap reading from a file in a lazy sequence
14:04	pdk	lazy version instead would give me an object that contains code to generate the next item in the sequence up to as many as i ask for
14:05	raek	then only as much as the list that was traversed will be read from the file
14:05	pdk	so in effect it'd pass me an object i can use as if it's an actual infinite sequence in the code
14:05	raek	http://gist.github.com/480608
14:05	pdk	and internally it doesn't generate any part of the sequence until you actually ask for a certain part
14:05	pdk	say the 1000th item
14:05	raek	I made that example for playing with when the lazy sequences are realized
14:05	Scriptor	sid3k: for example, haskell uses lazy evaluation to implement fibonacci
14:06	sid3k	thanks for great explonations and the example guys, I get it too
14:06	pdk	it won't have that 1000th item generated anywhere in advance and instead waits until i ask for it to generate it
14:06	raek	(also, lazy sequences are thread safe and each "cons cell" is only realized once)
14:07	pdk	and can continue to go along this way infinitely all within a finite amount of space because generation of items in the sequence is deferred until you ask for them
14:07	pdk	obv you'll still get stuck if you do something dumb like try to ask for every item in an infinite lazy sequence
14:07	sid3k	the dialog example seems very interesting, I'm trying it now
14:08	pdk	practical clojure just gives few 1 line examples that demonstrate the difference between eager vs lazy evaluation with their own version of range
14:08	raek	try, for example, doing (take 3 ...) of the sequence
14:08	raek	and the n doing it again on the same sequence
14:09	pdk	yeah if you want an item out of a lazy sequence you can pull it out with the same old functions as if it's any other type of sequence
14:09	pdk	though if the sequence is infinite and you try to get the whole of it by accident you can guess what happens
14:09	pdk	and instead of storing all the items of the sequence in advance you could ask for in advance it waits until you ask for a specific item to generate the sequence up to the point you want
14:10	pdk	then it throws away the stuff it had to generate in order to get up to the point you asked for
14:11	sid3k	wov, it's a really cool feature, as I see from the example
14:11	pdk	one book that would be helpful in learning how things are when you have lazy evaluation available vs when you don't would be purely functional data structures
14:12	raek	it lets you model many things as sequences, which traditionally would be imperative calls (like input from a file/socket/dialog)
14:12	pdk	all the code examples in the book are standard ml/haskell instead of lisp but it talks at length about the difference and shows you how it can affect things like runtime analysis on your code
14:13	pdk	aside from teaching you about those fancy pants data structures you didnt learn in cs 201 :p
14:15	pdk	for example they show you lots of variations on tree structures with properties that are useful in a functional environment
14:15	mister_m	hey I'm trying to follow this guide, http://wiki.unto.net/setting-up-clojure-and-slime , to get clojure set up with slime, and swank in emacs. but when I get to the end and try to M-x slime in emacs it just says [no match]
14:15	sid3k	pdk: I'm a physics student in Turkey, but I'm planning to watch MIT lectures, they would be helpful to get these stuff
14:15	pdk	shows you stuff like how the code for a red black tree looks in a functional vs traditional imperative environment and how the functional version is more concise and simpler to understand
14:16	raek	mister_m: the most simple way of starting swank is by strarting it outside emacs
14:16	sid3k	mister_m: try slime-connect after starting swank clojure
14:16	Scriptor	mister_m: try http://data-sorcery.org/2009/12/20/getting-started/
14:16	pdk	chris okasaki's phd thesis on functional data structures is basically the precursor to his book about them and the thesis is easy to find online
14:16	Scriptor	it's a more filled-out tutorial, so hopefully you'll be able to find any mistakes
14:17	Scriptor	pdk: how much better is the book than the thesis?
14:17	raek	"Previous versions of Swank Clojure bundled an Elisp library called swank-clojure.el that provided ways to launch your swank server from within your Emacs process. While swank-clojure is still distributed with the project, it's a much more error-prone way of doing things than the method outlined above." (technomancy's notes on: http://github.com/technomancy/swank-clojure)
14:18	pdk	i have the book on hand, i'll try to find the thesis real quick
14:18	Scriptor	I have a PDF of the thesis, so I'm just wondering if maybe I should invest in the book
14:18	pdk	i think it was around $30 on amazon and around 200 pages though the writing is pretty dense
14:19	sid3k	tyvm pdk, btw, do you guys blog? if yes, let me start to follow them
14:19	pdk	what do you mean by guy's blog
14:19	pdk	someone named guy or blogs from various people
14:20	Scriptor	pdk: no possessive in guy, just asking if you guys have a blog
14:20	pdk	oh i read "know" into there somehow haha
14:20	pdk	so at first glance "do you know guys blog?"
14:20	sid3k	pdk: sorry for my poor english, I mean, do you blog? (blog as a verb)
14:21	pdk	nah it was correct but i read it wrong the first time over
14:21	sid3k	:)
14:21	pdk	blog as a verb is proper form
14:21	pdk	i just read an extra word in there that wasnt there and misunderstood the first time around
14:21	sid3k	so, do you blog?
14:22	pdk	i wouldnt have enough to say if i did :p
14:22	pdk	i could swear i found a comparison of the thesis and book a while ago
14:23	Scriptor	sid3k: I just found this: http://twitter.com/planetclojure, you could give it a shot
14:23	sid3k	great, thanks
14:25	sid3k	pdk: tumblr makes blogging very easy to start, I think you should let people to follow you
14:25	sid3k	twitter counts btw
14:27	Scriptor	posterous is nice too
14:32	pdk	heh
14:35	pdk	also i managed to pull up the okasaki thesis now
14:41	pdk	im thumbing through to see what's in the book thats different from the thesis though right off the bat not counting the indices the book is about 50pg longer
14:43	pdk	hm there are two extra chapters that explain persistence and show a few common structures like red black trees done functionally
14:45	rubydiamond	Does anybody use irc bouncer like znc
14:49	bgs100	rubydiamond, I do
14:49	rubydiamond	bgs100: I have started using it recently.. znc
14:49	rubydiamond	I have 200GB slice..
14:49	bgs100	?
14:49	rubydiamond	in two days .. it says it has done 4GB of transfer
14:50	rubydiamond	bgs100: so is this 4GB because of znc /
14:50	rubydiamond	bgs100: ?
14:51	bgs100	rubydiamond, I dunno.
14:51	bgs100	I don't really know much about ZNC; I just have an account on a certain server.
14:52	bgs100	Ask on #znc ?
14:52	rubydiamond	bgs100: which server?
14:52	rubydiamond	are there any free providers?
15:23	mister_m	what do I do if something already exists when installing things with ELPA, but is not listed as installed
15:24	mister_m	can I force it to overwrite whatever file it's talking about
15:56	BobFunk	hey
15:56	BobFunk	trying to make a boring task interesting by learning clojure along the way, and am trying to do some log parsing with clojure
15:57	BobFunk	but am runing into out of memory problems
15:57	BobFunk	while doing quite basic stuff
15:58	BobFunk	just doing a count of the lines uses up my 3 gigs of memory it seems
15:58	BobFunk	doing it like this: http://gist.github.com/503695
15:58	BobFunk	guess there must be some better way of working with textfiles than this
15:59	raek	try (count (read-lines logfile))
15:59	raek	when you bind the head of the sequence to a variable
15:59	raek	the JVM cannot garbage collect any parts of it
16:00	raek	thus, the whole file will be in memory
16:01	BobFunk	ok - makes sense
16:02	Derander	BobFunk: there is no escaping the nesting ;-)
16:03	BobFunk	hehe
16:04	BobFunk	hmm, doesn't seem to help though
16:04	BobFunk	trying just: (count (read-lines "path-to-my-log-file.log"))
16:04	BobFunk	but memory use still just groving and groving with no result coming
16:05	BobFunk	ahh - result came now
16:05	BobFunk	and guess the gc might just not have kicked in - gonna try with a lower memory limit on the jvm
16:13	raek	you can still do a .readLine on the reader manually and cound the number of times it returns non-nil
16:18	mister_m	any clojure reading recommendations for someone new to the language?
16:18	mister_m	preferably the free kind of reading
16:20	qbg	Blogs are free
16:20	qbg	You could go to a library and try to get Programming Clojure
16:21	raek	there is some free pieces of The Joy of Clojure: http://manning.com/fogus/
16:21	raek	http://planet.clojure.in/ http://disclojure.org/
16:22	raek	also, some screencasts: http://clojure.blip.tv/
16:22	raek	there are other video series around too
16:23	qbg	Some material relating to Scheme might be good also depending on new you are to FP
16:24	tomoj	anyone know why some planet clojure feed items have their links fucked up?
16:24	tomoj	I wonder if it's planet clojure's fault or the feed author's faults?
16:40	LauJensen	Does anyone have an example of how Rings current session middleware is supposed to be used for memory storage?
16:41	dsop	y
16:42	LauJensen	mister_m: my blog on www.bestinclass.dk has quite a few articles that are new-comer friendly
16:42	LauJensen	(and also a couple that arent)
16:44	Bjering	Using counter-clockwise I have a problem adding the netty.jar, I have drag-dropt it into the IDE, copied it, and then added it to my build path (it is now among my referenced libraries). Yet when I import it I get ClassNotFoundException, the code used to work in Enclojure. Any hints as what I do wrong?
16:45	LauJensen	Bjering: Yea, from your description it sounds like you're not using Emacs
16:45	tomoj	(defn an-aleph-handler [ch r] (enqueue-and-close ch (a-ring-handler r))) sort of defeats the purpose, doesn't it?
16:49	fielcabral	#jering maybe you need to restart the repl to get the new class path? or maybe the (import ...) is mistyped? or the class path you changed is just for compilation and is not for Running
16:51	Bjering	fielcabral: Restarting the repl helped so that I could load it (ie it works) editor still highligt as error, restarting Eclipse now to see if that fixes that thing.
16:53	Bjering	fielcabral: Nope, editor still show it as error even though it works now when loaded into the repl. As if the editor-code checking my syntax pre-evaluation isnt using the new build path.
16:55	fielcabral	Bjering sorry I'm not very familiar with counter-clockwise though I love eclipse. I would hunt for a dialog specific to counter clockwise that lets you change a classpath.
17:03	Bjering	fielcabral: Found this http://groups.google.com/group/clojuredev-users/browse_thread/thread/53716a0cb2d5e694# and that did it, that is, closing the REPL as you said and then also project->clean
17:03	Bjering	thank you
17:04	fielcabral	welcome
17:04	fielcabral	Bjering i gotta try counter clockwise again one of these days
17:07	Bjering	I like it, but what do I know :) my problem is I am not only new to Clojure, I am new to Eclipse as well :) And haven't really programmed anything serious in a Java environment since 2002 or so... But I think I'll be ok, the namespace browser and the outline seems very nice.
17:11	fielcabral	Bjering yes I agree with you about the NS browser and outline. I'm hoping the eclipse debugger will let you step through code, set breakpoints, etc..
17:18	raek	which editor had that paredit-like thingy? ccw?
17:18	qbg	Yes
17:22	JoeyA	Quick question: I'm not familiar with Clojure (I've only done a little Scheme, which is different), but does Clojure predominantly use single application or multiple application?
17:22	JoeyA	In other words, if you apply an argument to, say, addition, does it yield a function which adds 3 (single applicative)?
17:22	JoeyA	Or do you have to apply all arguments up front? (or use a lambda or #(+ 3 %))
17:23	tomoj	are you asking if you can do ((+ 1) 2) to get 3?
17:23	JoeyA	yes
17:24	tomoj	no, you can't
17:24	tomoj	((partial + 1) 2) works
17:24	JoeyA	is partial a special operator that only works in that context?
17:24	tomoj	partial is just a function
17:24	JoeyA	oh
17:25	raek	it does something like (defn partial [f val] (fn [& args] (apply f (cons val args))))
17:25	raek	,(source partial)
17:25	clojurebot	java.lang.Exception: Unable to resolve symbol: source in this context
17:25	raek	~partial
17:26	clojurebot	It's greek to me.
17:26	tomoj	([f arg1] (fn [& args] (apply f arg1 args)))
17:26	raek	(source partial)
17:26	raek	hrm, yeah
17:27	JoeyA	Can you do this to create a partially applied function? #(function_of_5_args 1 2 %1 %2 5)
17:27	tomoj	sure
17:27	raek	yes, that will yield a 2-arg functoin
17:27	JoeyA	cool
17:29	JoeyA	I've been thinking about how to implement a sort of drag-and-drop programming facility for an application.
17:29	tomoj	so do we end up having to reimplement ring stuff for aleph?
17:30	JoeyA	One cool idea I'm thinking of applying to the project is that when you have a spot to drag a function, and you drag a function with too many arguments, it lets you go ahead and bind some of the parameters (rather than yell at the user for doing something wrong)
17:30	JoeyA	I'm not sure that idea would work so well in single-applicative style.
17:31	JoeyA	Anyway, thanks.
17:43	technomancy	JoeyA: single applicative functions like you're describing don't seem to be compatible with variable argument lists
17:44	technomancy	I think the term is currying
17:46	Derander	technomancy: 'tis indeed
17:46	Derander	uncurried functions, currying, etc.
17:46	Derander	s/un//
17:46	sexpbot	curried fctions, currying, etc.
17:47	technomancy	sexpbot: I didn't see a g there...
17:49	JoeyA	right
18:17	pdk	[17:27] <JoeyA> Can you do this to create a partially applied function? #(function_of_5_args 1 2 %1 %2 5) <- yes, you can also curry the function with (partial function 1 2 3 ...) if you know you want the first X arguments predefined and the rest after those left to be filled in as the function is called
18:18	pdk	e.g. (partial * 2) would basically be equivalent to #(* 2 %1) though the curried version with partial would let me tack on as many extra arguments as * can take
18:31	tomoj	it's #(apply * 2 %&)
18:32	pdk	OR THAT
18:33	JoeyA	Thanks
18:33	tomoj	-> ((partial * 1))
18:33	sexpbot	=> 1
18:33	tomoj	never thought about that
18:58	pdk	(doc ->)
18:58	clojurebot	"([x] [x form] [x form & more]); Threads the expr through the forms. Inserts x as the second item in the first form, making a list of it if it is not a list already. If there are more forms, inserts the first form as the second item in second form, etc."
19:09	lancepantz_	github should map anchor tags to line numbers
19:10	lancepantz_	i should be able to do http://github.com/nablaone/slime/blob/master/slime.el#2214
19:10	lancepantz_	and that go to 2214
19:11	tomoj	http://github.com/nablaone/slime/blob/master/slime.el#L2214
19:11	lancepantz_	nice!
19:11	lancepantz_	you always come through for me tomoj :)
19:11	tomoj	you can click on the line numbers to get those links
19:11	lancepantz_	i see
19:27	pdk	(doc read-lines)
19:27	clojurebot	"clojure.contrib.duck-streams/read-lines;[[f]]; Like clojure.core/line-seq but opens f with reader. Automatically closes the reader AFTER YOU CONSUME THE ENTIRE SEQUENCE."
19:27	pdk	(doc line-seq)
19:27	clojurebot	"([rdr]); Returns the lines of text from rdr as a lazy sequence of strings. rdr must implement java.io.BufferedReader."
19:28	wwmorgan	what's the preferred way to submit patches?
19:29	kencausey	http://www.assembla.com/wiki/show/clojure
20:47	lancepantz_	,(let [x (filter odd? [2 4])] (when (first x) x))
20:47	clojurebot	nil
20:48	lancepantz_	^ is there a cleaner way to do that?
20:48	lancepantz_	making a filtered seq return nil if it's empty
20:48	wwmorgan	,(seq (filter odd? [2 4]))
20:48	clojurebot	nil
20:50	lancepantz_	wwmorgan: ty
20:53	pdk	(doc when)
20:53	clojurebot	"([test & body]); Evaluates test. If logical true, evaluates body in an implicit do."
21:09	rhudson	don't we all
23:33	Bahman	Hi all!
23:55	gstamp	,(clojure.stacktrace/root-cause (Exception.))
23:55	clojurebot	#<Exception java.lang.Exception>