#clojure – 2010-10-24

2010-10-24

01:03	defn	oh my god. so much email to catch up on post-conj
02:01	wooby	defn: sup!
04:51	_ulises	morning
05:50	_ulises	how can I reset an ns so that I don't get illegal bindings?
06:54	raek	_ulises: either (in-ns 'some-other-ns) (remove-ns 'the-ns) or (ns-unmap 'the-ns 'conflicting-var)
07:54	_ulises	raek: thanks
08:10	ulises	why am I getting 'unmatched delimiter )' here: http://paste.lisp.org/display/115855
08:10	ulises	:(
08:14	MayDaniel	ulises: The metadata needs to come before the namespace.
09:07	raek	_ulises: also, it is possible to do it like this: lastfm-clj.core
09:07	raek	eh
09:07	raek	(ns lastfm-clj.core "Core functions for lastfm-clj" {:author "Ulises Cervino Beresi"} ...)
09:41	bytesource	Hi all! I am currently reading the chapter on HBase of 'Clojure in Action'. I downloaded HBase but have no idea of how to install it on Linux. I couldn't find a simple manual either on the web. Does anybody know how to do the install? I am using Leiningen and Emacs.
09:46	kumarshantanu	ubuntu has apt-get for HBase/Hadoop?
09:48	tomoj	no
10:02	ulises	MayDaniel: thanks
10:32	Sweetshark	How do I access the static "class" member of a class object, i.e. what I write "Object.class" in Java returning the type?
10:33	_ulises-	I believe it's class
10:33	_ulises-	,(class "foo")
10:33	clojurebot	java.lang.String
10:33	tomoj	,String
10:33	clojurebot	java.lang.String
10:33	_ulises-	oh, wait
10:33	_ulises-	(,String/class)
10:33	_ulises-	,(String/class)
10:33	clojurebot	java.lang.NoSuchFieldException: class
10:34	_ulises-	,String/class
10:34	clojurebot	java.lang.Exception: Unable to find static field: class in class java.lang.String
10:34	_ulises-	hrm
10:34	tomoj	,(class String)
10:34	clojurebot	java.lang.Class
10:34	kumarshantanu	,(String/getClass)
10:34	clojurebot	java.lang.NoSuchFieldException: getClass
10:35	tomoj	Sweetshark: (just write "Object")
10:35	kumarshantanu	,(.getClass "Whatever")
10:35	clojurebot	java.lang.String
10:37	Sweetshark	tomoj: actually (class String) looks like what I want ...
10:41	Sweetshark	meh, not quite ... but (Class/forName "java.lang.String") should do for now ...
10:43	_ulises-	Sweetshark: what are you trying to do anyway?
10:44	Sweetshark	_ulises-: http://api.openoffice.org/docs/java/ref/com/sun/star/uno/UnoRuntime.html#queryInterface%28java.lang.Class,%20java.lang.Object%29
10:44	tomoj	Sweetshark: what?
10:44	tomoj	,(= (Class/forName "java.lang.String") String)
10:44	clojurebot	true
10:44	tomoj	just write "String"...
10:45	_ulises-	right
10:48	rdeshpande	anyone else having issues getting labrepl to 'lein deps'?
10:50	Sweetshark	tomoj _ulises-: well it parses of the repl, thanks so far ...
10:52	_ulises-	rdeshpande: I've cloned a fresh labrepl and doing lein deps as we speak
10:52	_ulises-	so far, no issues
10:57	_ulises-	rdeshpande: right, lein deps has finished without issues, what issues are you encoutering? what arch? which version of labrepl? etc.
11:03	defn	hey all
11:06	_ulises-	hey defn
11:08	rdeshpande	_ulises-: im seeing this http://pastie.org/1245060 - but where is 1.2.0beta1 coming from? i dont' see 'beta1' anywhere grepped in the repo. shouldn't it just be getting 1.2?
11:09	raek	http://build.clojure.org/releases/org/clojure/clojure/ it exists here
11:09	_ulises-	this is what I have on my project.clj: http://pastie.org/1245065
11:09	_ulises-	see if there's anything different with yours?
11:10	maravillas	perhaps it's a transitive dependency
11:12	rdeshpande	_ulises-: nope, same exact ting
11:12	maravillas	is your labrepl up to date?
11:12	rdeshpande	yep
11:12	rdeshpande	just cloned
11:12	_ulises-	rdeshpande: tried pulling from ... oh
11:13	_ulises-	I can also see you're on OS X, like me :/
11:13	maravillas	hm, i just grabbed its deps and got 1.2, not beta1
11:13	maravillas	oh, nevermind
11:13	_ulises-	same for me
11:13	maravillas	it's a dev-dep
11:13	rdeshpande	could it be something in my home dir?
11:13	maravillas	either autodoc or swank-clojure must depend on it
11:14	maravillas	regardless, though, i was able to grab it
11:14	rdeshpande	hmm
11:14	rdeshpande	very odd
11:15	maravillas	hm, nope
11:15	maravillas	well, that's beside the point anyway
11:15	maravillas	actually, i bet i had mine cached locally
11:18	_ulises-	rdeshpande: I suppose that telling you to start afresh is pointless?
11:19	rdeshpande	not sure how much fresh it could be :/
11:19	rdeshpande	*how much more
11:19	_ulises-	did you just do a clone?
11:19	_ulises-	I did mine when you asked the question actually
11:20	defn	Can someone refresh my memory on :use in the (ns) macro
11:20	defn	specifically how to use :as with :use
11:20	maravillas	_ulises-: the latest isn't working for me either, after i deleted the cached copy in ~/.m2
11:21	defn	(:use clojure.contrib [io :as foo])
11:21	_ulises-	maravillas: oh :(
11:22	_ulises-	what about leiningen? do you have the latest version?
11:22	maravillas	i don't understand why, unfortunately, since beta1 is still available on the build site
11:27	maravillas	rdeshpande: as a workaround, you could try downloading clojure-1.2.0-beta1.jar, .jar.sha1, .pom, and .sha1 from http://build.clojure.org/releases/org/clojure/clojure/1.2.0-beta1 and putting them in ~/.m2/repository/org/clojure/clojure/1.2.0-beta1
11:27	maravillas	it's not the right answer...someone else might have more insight
11:32	wooby	defn: http://gist.github.com/284277
11:32	KLll	guys
11:33	KLll	I have a vector
11:33	KLll	(def some-vec [1 2 3])
11:33	KLll	what's the best way to modify it
11:33	defn	wooby: !!
11:33	_ulises	KLll: you don't?
11:33	KLll	(def some-vec (assoc some-vec 2 3))
11:33	KLll	or what?
11:33	defn	wooby: you sir, are a saint
11:34	_ulises	why do you need to modify it?
11:34	KLll	I want to add to it
11:34	KLll	or change it
11:34	KLll	for instance I have a vector of maps or listeneres to events
11:35	_ulises	assoc is possibly what you want
11:35	wooby	KLll: in clojure the modification of things by re-deffing them is discouraged, there are special types for handing variables that can change over time. atom is probably the one you should check out
11:35	KLll	adding a listener requires changing a map, then associng that map into the vector, then I have to rebind the vector
11:35	_ulises	keep in mind that if you do (assoc [] 1 1) you'll get out of bounds exceptions
11:35	_ulises	also what wooby said
11:35	wooby	(def my-vec (atom [1 2 3]))
11:36	wooby	KLll: http://clojure.org/atoms
11:37	wooby	i now giggle every time i see fib used as an example anywhere
11:38	maravillas	it's now possible to reference fib ironically
11:39	KLll	the thing is
11:39	kumarshantanu	is it possible to access clojure.repl/source in code? (instead of REPL)
11:39	KLll	in nearly every program I have some state
11:39	kumarshantanu	,(source source)
11:39	clojurebot	java.lang.Exception: Unable to resolve symbol: source in this context
11:39	KLll	that changes
11:39	KLll	so the atoms are the way to do it?
11:39	kumarshantanu	,(clojure.repl/source source)
11:40	clojurebot	Source not found
11:40	raek	keyword args question: if I do a (foo :a 1 :b 2) call, I want to get 'options' bound to {:a 1, :b 2}. is (defn foo [& {:as options}] ...) the correct way to do that?
11:40	wooby	kumarshantanu: (use 'clojure.contrib.repl-utils) (source atom)
11:41	raek	or, I guess my question is "when does function arguments automagically become maps="
11:41	wooby	KLll: not always - there are also refs and agents
11:41	KLll	how do you decide between using an atom and using a ref
11:42	raek	KLll: refs are for when you might need to coordinade changes of multiple refs
11:42	raek	with atoms, you can't do that
11:42	KLll	I see that
11:43	raek	so, if you have something internally that only you use, (like a counter or something) you could use an atom
11:43	raek	but when others need to use it too, it might be better to use refs to be on the safe side
11:44	wooby	good screencasts that cover the use cases for refs/atoms/agents: http://www.pluralsight-training.net/microsoft/olt/course/toc.aspx?n=clojure-concurrency-tutorial
11:44	bmh	does clojure have a function like Haskell's zip or zipWith? (map over two collections simultaneously)
11:45	opqdonut	,(map + [1 2 3] [4 5 6])
11:45	clojurebot	(5 7 9)
11:45	bmh	oh. That's convenient.
11:45	opqdonut	,(map vector [1 2 3] [4 5 6])
11:45	clojurebot	([1 4] [2 5] [3 6])
11:46	wooby	bmh: there's also zipmap
11:46	opqdonut	which is mostly unrelated
11:46	wooby	does the haskell thingy not return a map?
11:46	bmh	it doesn't
11:47	wooby	ah
11:47	raek	zip returns tuples
11:47	bmh	The type of zip is: [a] -> [b] -> [(a,b)]
11:47	wooby	ignore me :)
11:47	opqdonut	haskell's zip does what map vector does
11:47	opqdonut	zipWith does what clojure's map does
11:48	bmh	sometimes I think programming in clojure would be easier if I didn't know scheme/haskell
11:48	bmh	I'd have read the manual.
11:54	KLll	hi
11:56	KLll	sup
11:56	TheAnimal4	Yo yo yo KLll
12:01	defn	wooby: fib is important to programming
12:01	defn	factorial is also really important to what we do everyday.
12:02	defn	thinking out loud: im not sure what i'd do if i didnt have factorial, probably just code hello world over and over
12:03	rdeshpande	bmh: what is your impression so far coming from haskell?
12:04	bmh	rdeshpande: from scheme might be a little more fair. I really dig the loop-recur construct
12:04	bmh	multimethods are wonderful
12:07	defn	i like functions :D
12:07	_ulises	I recently found a use for protocols ... go figure :D
12:07	defn	im making a conscious effort post-conj to use some more protocols in my code
12:07	_ulises	well, more like I just came across a case where I thought "thank god for protocols"
12:08	defn	chouser's finger tree code makes some nice use of protocols
12:09	jarpiain	Ok, my port of the clojure compiler into clojure seems now capable of compiling itself. Time to release :)
12:09	jarpiain	http://github.com/jarpiain/cljc
12:09	bmh	rdeshpande: I think the interop is my favorite feature. At the absolute worst, it makes clojure as good as java.
12:09	bmh	Praise be to Technomancy for giving us Lein.
12:09	defn	don't forget the cake :)
12:10	gfrlog	clojure is not as good as java at worst
12:11	gfrlog	it lacks most of the static benefits
12:11	defn	if i wanted to use statics i wouldnt be using clojure in the first place
12:11	opqdonut	why not
12:12	defn	i want a dynamic language.
12:12	gfrlog	my point was that if I'm going to resort to using clojure by just calling java, I'll get a lot more benefit out of using java as java
12:12	opqdonut	clojure could be a great dynamic language with optional static features
12:12	opqdonut	common lisp is quite good at being both static and dynamic
12:12	defn	gfrlog: it depends.
12:12	bmh	I want a type system ;-)
12:13	gfrlog	defn: what do you mean?
12:13	bmh	It's absurd that the jvm doesn't support tco
12:13	gfrlog	bmh: it makes sense to me, assuming they designed it for java
12:13	defn	gfrlog: it depends on what you care about. if you're only concerned with the benefits of statics then okay, but who the heck cares about just one thing?
12:14	defn	i want an expressive language. i want maintainable code.
12:14	bmh	gfrlog: Not in the slightest. Java is an OO language. You program in an OO language by calling methods.
12:14	gfrlog	defn: nobody of course, but static benefits are huge
12:14	gfrlog	defn: I'm assuming a hypothetic world (i.e., "at worst") where the best use you can make of clojure is to pretend it's java using the interop
12:14	bmh	gfrlog: If you don't have tail-calls, eventually your method calls smash the stack. Therefore, you can't write OO java!
12:14	KLll	I find my code less maintainable in clojure
12:15	defn	gfrlog: yeah, in the real world things are a bit different ;)
12:15	gfrlog	bmh: clearly you can -- you use for loops instead of recursive algs
12:15	gfrlog	defn: they are. I spend too much time on theory sometimes.
12:15	KLll	any recursion can be changed into iteration
12:15	somnium	bmh: have you read GVR's manifesto against tail calls and fp in general?
12:15	kumarshantanu	any CCW user here?
12:16	bmh	somnium: I did. I don't think much of him.
12:16	bmh	somnium: Have you read Xavier Leroy's rants about kernel threads in Ocaml?
12:16	defn	who is GVR
12:16	defn	oh... nvm
12:16	bmh	Guido
12:16	defn	guido
12:16	defn	if you have a link ill entertain it :)
12:16	somnium	bmh: I have not. I just wanted to mention my amazement that a language designer would be openly hostile to such fundamentally useful features
12:17	bmh	somnium: I think Guido is a turd.
12:17	defn	somnium: the human condition sucks
12:17	defn	you make a decision so you have to hate all other decisions or something
12:17	defn	it's ludicrous
12:18	gfrlog	sunk cost fallacy
12:18	gfrlog	or something similar
12:18	_ulises	perhaps larry wall is the king of inflammatory remarks
12:18	bmh	Xavier is a bit of a different story. Fire up your favorite GNU/Linux distro and type 'man pthread'
12:18	defn	perhaps larry wall is the worst speaker i've ever seen
12:18	bmh	"linuxthreads-0.10 by Xavier Leroy", it makes his opposition to kernel threads seem slightly less insane
12:18	gfrlog	$ man pthread
12:18	bmh	defn: I agree entirely.
12:18	gfrlog	No manual entry for pthread
12:18	bmh	pthreads, sorry
12:18	defn	bmh, did we meet yesterday?
12:19	gfrlog	much better
12:19	bmh	defn: We didn't.
12:19	defn	heh sorry -- im trying to do post-conj association
12:19	defn	so many twitter handles and nicks and names in my head atm
12:19	bmh	I last saw Larry Wall speak in... 2007?
12:19	gfrlog	I was that guy sitting in one of the chairs
12:19	defn	gfrlog: omg. same.
12:20	gfrlog	defn: damn, we should've talked
12:20	defn	i know. next time you're at a conference talk to the guy in the chair, that'll be me.
12:20	gfrlog	okay
12:20	defn	unless he's not, in which case: keep trying.
12:20	gfrlog	two or three tries max I'm sure
12:21	defn	the sarcasm is palpable
12:21	gfrlog	and sticky
12:21	defn	indeed. investigates the palp closely
12:22	defn	as in palpus
12:22	bmh	Does clojure have a function like "conj-with" for shoving things into a map? (i.e. If a key already exists, then use some function to combine the values)
12:22	_ulises	bmh: merge-with
12:22	_ulises	,(doc merge-with)
12:22	clojurebot	"([f & maps]); Returns a map that consists of the rest of the maps conj-ed onto the first. If a key occurs in more than one map, the mapping(s) from the latter (left-to-right) will be combined with t...
12:23	defn	will be combined with the mapping in the result by calling (f val-in-result val-in-latter).
12:24	KLll	Hi
12:24	TheAnimal4	Greetings KLll
12:24	KLll	my greeter bot :P
12:24	defn	epic.
12:24	defn	Hi
12:24	TheAnimal4	Greetings defn
12:24	KLll	:P
12:24	gfrlog	clojurebot: hey
12:24	clojurebot	hey is for horses
12:25	bmh	_ulises: sure, but merge with noms a pile of maps, oh, I guess it'll work
12:25	KLll	hello
12:25	TheAnimal4	Greetings KLll
12:25	KLll	sup
12:25	TheAnimal4	Yo yo yo KLll
12:25	_ulises	bmh: you can always use {} as one of the maps
12:25	_ulises	bmh: I suppose you could also use reduce?
12:26	defn	heh -- any new language, if it wants to be successful, needs to have a separate channel for the inevitable irc bot experimentation that will occur
12:26	_ulises	I'm not familiar with conj-with unfortunately
12:26	KLll	next up: let's plug it into Warhammer item database so it will quote stats into the channel :P
12:26	bmh	KLll: why don't you write a bot that finds arbitrage opportunities in Warhammer? ;-)
12:26	KLll	maybe I should look into some textual analysis
12:27	defn	linkparser maybe?
12:27	KLll	so it picks out buzzwords out of random chat
12:27	KLll	then repeats statements about that buzzword from weeks ago
12:27	defn	"web 2.0", "agile", etc.
12:27	KLll	that would troll many people
12:28	defn	set up some future/promise or agent type thing that, when someone responds, tells them in no uncertain terms they have been trolled
12:28	KLll	hahahah
12:29	defn	there's this hillarious library for clojure that generates business BS, like "synergizing business ROI with gold futures"
12:29	defn	err for ruby, it's called "faker"
12:30	KLll	something like that
12:30	KLll	I recall a channel where they had a bot named
12:30	KLll	gothgirl19
12:30	KLll	or something like that
12:31	KLll	it regurtiated back statements converted into questions
12:31	defn	heh yes ive seen that trolling mechanism in action -- i used to know someone who did a similar thing with a bot named "cutie5484"
12:31	KLll	when they looks at chat logs there were a surprising amount of people trying to pick up the bot and talking to the bot for hours
12:32	kumarshantanu	is it possible to get the name of a function as string? map? --> "map?"
12:32	defn	sure
12:33	gfrlog	um
12:33	gfrlog	really?
12:33	kumarshantanu	defn: how?
12:33	gfrlog	is it in the metadata?
12:33	somnium	kumarshantanu: from the runtime representation?
12:33	defn	there are a few ways
12:33	defn	,(str (:name (meta #'and)))
12:33	clojurebot	"and"
12:34	kumarshantanu	,(str (:name (meta map?)))
12:34	clojurebot	""
12:34	KLll	why the #'?
12:34	defn	interesting...
12:34	KLll	isn't ' enough??
12:35	gfrlog	'(let [my-fun vector?] (str (:name (meta #'my-fun))))
12:35	KLll	,(str (:name (meta 'map?)))
12:35	clojurebot	""
12:35	gfrlog	,(let [my-fun vector?] (str (:name (meta #'my-fun))))
12:35	clojurebot	java.lang.Exception: Unable to resolve var: my-fun in this context
12:35	gfrlog	I suck at commas
12:35	defn	,(meta 'map?)
12:35	clojurebot	nil
12:35	defn	,(meta #'map)
12:35	clojurebot	{:ns #<Namespace clojure.core>, :name map, :file "clojure/core.clj", :line 2079, :arglists ([f coll] [f c1 c2] [f c1 c2 c3] [f c1 c2 c3 & colls]), :added "1.0", :doc "Returns a lazy sequence consisti...
12:35	gfrlog	,(let [my-fun vector?] (str (:name (meta my-fun))))
12:35	KLll	,(str (:name (meta #'map?)))
12:35	clojurebot	""
12:35	clojurebot	"map?"
12:35	defn	there ya go :)
12:35	KLll	,(meta 'map)
12:35	clojurebot	nil
12:35	defn	there's another way too but im failing to remember it
12:36	KLll	seriously, what's the difference between ' and #'
12:36	raek	,(class 'conj)
12:36	clojurebot	clojure.lang.Symbol
12:36	raek	,(class #'conj)
12:36	defn	quote, var quote
12:36	clojurebot	clojure.lang.Var
12:37	kumarshantanu	how do I #" inside a macro?
12:37	defn	KLll: #' is var quote, ' is quote
12:37	somnium	ah, map? is defined with `def', not `defn', so I guess the metadata doesn't get attached to the function object?
12:37	raek	the metadata usually go on the var object rather than the fn object
12:37	KLll	could be
12:38	raek	but since 1.2, fns can have metadata too
12:38	defn	,(meta #'map?)
12:38	clojurebot	{:ns #<Namespace clojure.core>, :name map?, :file "clojure/core.clj", :line 149, :arglists ([x]), :doc "Return true if x implements IPersistentMap", :added "1.0"}
12:38	somnium	I think defn commutes the metadata now
12:38	somnium	,(meta map?)
12:38	clojurebot	{:line 153}
12:38	defn	gotta var quote
12:38	kumarshantanu	defn: how can i var-quote inside a macro?
12:39	defn	kumarshantanu: i have code somewhere, one sec
12:39	kumarshantanu	#'~fn-name
12:39	wooby	jarpiain: re: compiler, neat!
12:39	somnium	defn: if you don't know the name it's hard to var-quote :P
12:39	KLll	does clojure have date stuff, or do I have to use java.util.Date?
12:39	defn	;)
12:39	raek	kumarshantanu: it is not known at macro expansion time what var the symbol fn-name will refer to
12:39	defn	somnium: oh right
12:40	raek	KLll: clj-time is a neat lib (a wrapper for Joda time)
12:40	raek	javas date classes are a mess
12:40	defn	no doubt
12:41	KLll	not really once you use GregorianCalendar :P
12:41	raek	joda time makes the dates immutable, so they work pretty well with clojure
12:41	KLll	I really like the mutators on GregorianCalendar
12:41	KLll	they are really neat
12:42	defn	im outta here, folks
12:42	raek	kumarshantanu: if you have the symbol foo and want "foo", you can simply use the function 'name'
12:42	raek	,(name 'foo)
12:42	clojurebot	"foo"
12:43	kumarshantanu	raek: I am passing a function to a macro, and want to find out the name inside that macro
12:44	defn	kumarshantanu: where does the function come from
12:44	defn	what if you get an anonymous function?
12:44	raek	kumarshantanu: the fn object itself does not know wich names are bound to it
12:44	kumarshantanu	actually I am trying to diagnose some defects -- so the macro asserts few values and then (should) tell which function failed -- so I need the name
12:45	raek	a macro could of course look at the unevaluated argument and if it is a symbol, treat that as the name for it
12:45	somnium	,(meta (resolve 'map?))
12:45	clojurebot	{:ns #<Namespace clojure.core>, :name map?, :file "clojure/core.clj", :line 149, :arglists ([x]), :doc "Return true if x implements IPersistentMap", :added "1.0"}
12:45	KLll	(re-find #"time" "don't have time")
12:45	KLll	,(re-find #"time" "don't have time")
12:45	clojurebot	"time"
12:46	raek	kumarshantanu: you could store the unevaluated argument. in that case, you get the code for the expression that failed
12:46	somnium	,(let [fname 'map?] `(prn ~(meta (resolve fname))))
12:46	clojurebot	(clojure.core/prn {:ns #<Namespace clojure.core>, :name map?, :file "clojure/core.clj", :line 149, :arglists ([x]), :doc "Return true if x implements IPersistentMap", :added "1.0"})
12:46	somnium	kumarshantanu: perhaps that will work?
12:47	kumarshantanu	AH! got it -- (:name (meta (resolve (quote ~f?))))
12:48	kumarshantanu	f? is the function name the macro accepts
12:50	kumarshantanu	somnium: raek: thanks
12:50	KLll	!time
12:50	somnium	kumarshantanu: cheers
12:50	KLll	!time
12:53	KLll	!time
12:53	Upper	I need a help here pleaseI can't find the error - http://pastebin.com/JvZgH1E7
12:54	Upper	was created a loop/when to print a different message in each iteration
12:55	KLll	so if I do (defn fun1 ....)
12:55	KLll	then make some vector [fun1]
12:55	KLll	and then re-def it (defn fun1 something else ...)
12:55	KLll	the vector now holds the old one ?
12:56	KLll	!time
12:56	TheAnimal4	Time is java.util.GregorianCalendar[time=1287939389109,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Europe/Prague",offset=3600000,dstSavings=3600000,useDaylight=true,transitions=141,lastRule=java.util.SimpleTimeZone[id=Europe/Prague,offset=3600000,dstSavings=3600000,useDaylight=true,startYear=0,startMode=2,startMonth=2,startDay=-1,startDayOfWeek=1,startTime=3600000,startTimeMode=2,endMo
12:56	raek	Upper: you don't have any call to recur
12:56	KLll	oops :P
12:57	raek	Upper: see http://clojure.org/special_forms#Special%20Forms--%28recur%20exprs*%29
12:58	Upper	hm right
13:01	raek	Upper: the basic code building block of a functional programming language is an expression, not a statement
13:01	raek	(+ 2 i) means take i and add two and return that. it does not change i
13:14	kumarshantanu	is it a bug that pos? throws exception on nil?
13:15	kumarshantanu	,(pos? nil) ; expected false, right?
13:15	clojurebot	java.lang.NullPointerException
13:15	gfrlog	,(pos? "haha I'm a string")
13:15	clojurebot	java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Number
13:15	gfrlog	,(num nil)
13:16	clojurebot	nil
13:39	riddochc	Anybody got suggestions for decent reading material to understand Java IO, nio, netty, etc. from a Clojure context? Got a little project I'm playing with, and aleph seems nicely suited to it, but I'm running up against a pretty steep learning curve here.
13:41	riddochc	I suspect non-Clojure contexts would do, too, since I'm familiar enough with the Clojure side of things to be able to translate it... but I'm not very familiar with the Java APIs, and they seem tremendously more complicated than I would've expected.
13:47	rhudson	riddochc, I suspect you'd do well to start with the netty documentation.
13:47	rhudson	I don't think you really have to understand the details of nio (thankfully!) to grok netty
13:48	rhudson	All you really need to know about nio to start with is that the asynch stuff is based on the OS select
13:49	riddochc	rhudson: Hm. I'll try reading it again, then.
13:49	riddochc	rhudson: Is it just me, or does everything seem to assume that a protocol will be layered on top of HTTP?
13:50	rhudson	Seems the way of the world these days...
13:50	rhudson	The advantage is that the server only needs to open ports 80 & 443
14:00	KirinDave	Hey
14:00	gfrlog	hi
14:00	KirinDave	Earlier someone had been linking some new screencasts to all different parts of clojure
14:00	KirinDave	Like several on vars, several on refs, etc
14:00	KirinDave	Does anyone still have that link? I lostit
14:01	maravillas	the full disclojure screencasts?
14:01	raek	this one? http://www.pluralsight-training.net/microsoft/olt/course/toc.aspx?n=clojure-concurrency-tutorial
14:01	maravillas	http://vimeo.com/channels/fulldisclojure
14:01	KirinDave	raek: Those, idneed.
14:01	KirinDave	Thanks
14:01	raek	KirinDave: this is a goldmine: http://alexott.net/en/clojure/video.html
14:02	KirinDave	Dang
14:02	KirinDave	That's solid.
14:03	TakeV	What is exactly meant by "synchronous" and "unsynchronous" when talking about the difference between refs and atoms? And coordinated for that matter.
14:04	gfrlog	I can explain it after this chess game
14:05	TakeV	Sure. :)
14:05	KirinDave	So my webmachine->clojure port is in basic working order.
14:05	KirinDave	It doesn't handle everything and the tests aren't there, but I'm considering open sourcing it.
14:05	gfrlog	crap I lost
14:05	KirinDave	I'm not sure if I should do so today or tomorrow.
14:06	KirinDave	Like today is the tail-end of the conj, so...
14:06	gfrlog	TakeV: refs and atoms are both synchronous, so I think that issue should only come up when comparing either to agents
14:06	gfrlog	does that sound right?
14:06	KirinDave	gfrlog: Yeah
14:07	TakeV	gfrlog: I'm not sure what that term means, though. Likewise when discussing if they are coordinated or not.
14:07	gfrlog	TakeV: okay, so a for the synchronous ones (refs/atoms)
14:07	KirinDave	TakeV: Where did you see this?
14:08	gfrlog	they are evaluated in the current running thread, so your code doesn't proceed until the expession is finished evaluating
14:08	gfrlog	in contrast, when you send a function to an agent, the (send) call returns immediately, and the function gets evaled later on some other thread
14:09	gfrlog	so that's the sync/async distinction -- did it make sense?
14:09	TakeV	It does. Sounds somewhat like how locking works.
14:09	gfrlog	I think the explainer part of my brain is a bit muddled
14:09	KirinDave	TakeV: While it might involve locks, that's not what's going on
14:10	KirinDave	TakeV: Agents receive work queues.
14:10	KirinDave	TakeV: Atoms and refs do not.
14:10	KirinDave	TakeV: Agents work in the threadpool, atoms and refs do not
14:10	gfrlog	the fns sent to atoms and refs get evaled immediately while your thread execution waits
14:11	TakeV	What about coordination?
14:11	gfrlog	only refs are coordinated
14:11	TakeV	What does it mean?
14:11	gfrlog	what it means is that you can update several at once, and the whole action is atomic, like a database transaction
14:11	KirinDave	If you make a transaction over multiple refs, they all get updated or do not
14:12	gfrlog	and no other thread can see them in some intermediate state
14:12	TakeV	Thank you for the explanations. :)
14:12	gfrlog	no probalo
14:14	gfrlog	,(deref (ref 10))
14:14	clojurebot	10
14:15	gfrlog	,(detain (tain 10))
14:15	clojurebot	java.lang.Exception: Unable to resolve symbol: detain in this context
14:49	polypus	~ping
14:49	clojurebot	PONG!
14:49	Upper	what the difference between (juxt) and (do) ? with both I can execute two operations
14:49	gfrlog	woah
14:50	Upper	i dont know juxt exectly
14:50	gfrlog	juxt combines some functions into a new function
14:50	gfrlog	,(juxt first last)
14:50	clojurebot	#<core$juxt$fn__3661 clojure.core$juxt$fn__3661@11a74ef>
14:50	gfrlog	so that returns a new function
14:50	gfrlog	(let [f (juxt first last)] (f [6 7 8 9 10]))
14:51	Upper	hmm i got
14:51	gfrlog	,(let [f (juxt first last)] (f [6 7 8 9 10]))
14:51	clojurebot	[6 10]
14:51	Upper	cool
14:51	gfrlog	the new function calls both of the functions supplied to it and returns a vector of the results
14:51	raek	Upper: do is useful when you need to do side-effects
14:51	gfrlog	,(do (+ 3 4))
14:51	clojurebot	7
14:52	gfrlog	hmm
14:52	raek	(defn trace [x] (do (println "value: " x) x))
14:53	raek	Upper: you can then wrap that trace function around an expression to make clojure print it when it is evaluated
14:53	rhudson	,(let [f (first second last)] (f [1 2 3 4 5]))
14:53	clojurebot	java.lang.IllegalArgumentException: Wrong number of args (2) passed to: core$first
14:53	Upper	interesting
14:54	rhudson	,(let [f (juxt first second last)] (f [1 2 3 4 5]))
14:54	clojurebot	[1 2 5]
14:54	raek	Upper: however, function bodies alreade has an "implicit do", so you don't need to write the do in that case
14:56	Upper	usually I use do like a "then" of a cond, If I just open two parenthesis the second turn an else
14:57	Upper	I understood
14:58	raek	ah, ok... sorry for over-explaining... :)
14:58	serabe	hi
15:01	raek	anyone happen to know if a java.net.Socket is completely closed when both its InputStream and OutputStream are closed? or do I have to close the Socket object too?
15:02	somnium	raek: you might need an AbstractSocketCloserFactoryFactory to really be safe
15:03	raek	:P
15:04	raek	man... factory-factories... do they really exist?
15:05	raek	no wait. don't tell me. I don't wanna know...
15:05	dakrone	raek: http://ws.apache.org/xmlrpc/apidocs/org/apache/xmlrpc/server/RequestProcessorFactoryFactory.html
15:05	somnium	http://www.docjar.org/docs/api/org/outerj/pollo/xmleditor/FactoryFactory.html
15:05	firepoet	Ouch
15:14	rata_	hi
15:15	Upper	can i break a code in clojure? I need to stop because it is returning two values.
15:16	drewr	Upper: (throw (Exception.))
15:18	Upper	:) works
15:19	rata_	Upper, for debugging?
15:28	Upper	no. to final use
15:28	Upper	lazy to find a good solution
15:30	gfrlog	creating an infinite seq of primes elegantly is surprisingly tricky
15:31	rata_	gfrlog, why?
15:32	gfrlog	rata_: particularly if by "elegantly" we mean something you can create with (iterate), such that it doesn't require much memory and doesn't compute in large chunks, and is efficient (i.e., doesn't use division)
15:35	gfrlog	it took me several tries over the course of the conj
15:35	Upper	, (doc yield)
15:35	clojurebot	Excuse me?
15:35	gfrlog	clojurebot: are your responses hard-coded?
15:35	clojurebot	It's greek to me.
15:35	Upper	lol
15:35	gfrlog	clojurebot: you mean coded in greek?
15:36	clojurebot	excusez-moi
15:48	technomancy	icey: I think I missed you at the conj; bummer.
15:48	technomancy	how goes the plugin task?
15:54	polypus	anybody here done server push (comet, websockets, etc) from clojure?
15:58	Upper	are the something wrong here? (dotimes [n 100] (test 0 1 n))
15:58	Upper	it returns "nil" executing 1 time only
15:58	Upper	neither call my function
15:58	jackdempsey	technomancy: fwiw that deps issue didn't matter. (use 'compojure) is no longer valid i guess since 0.4 or something. thx for the help
15:59	qbg	Upper: Are you sure your function isn't being called?
16:00	Upper	i guess, my function always return a message with println
16:00	technomancy	jackdempsey: good to know.
16:01	Upper	exist other ways to make a loop?
16:01	qbg	Upper: Post the code that isn't working
16:02	qbg	Including the definition of test
16:02	qbg	Do you get an error when loading your code? test is also the name of a function in clojure.core
16:06	Upper	qbg: see http://pastebin.com/g2HkDdP4 - and I do (loopTest 100)
16:09	qbg	It looks like quadradoPerfeito is broken
16:12	qbg	When I run your code it is throwing the exception that you throw, so that is why it is only being run once
16:13	Upper	ah maybe
16:13	qbg	Also, the cond has two :else conditions statements
16:13	qbg	*conditions
16:13	qbg	And the return value of the cond form isn't even used!
16:14	qbg	If the first :else case of the cond is ever invoked, you will get a NullPointerException because you have an extra set of parens
16:15	qbg	That first :else condition also does some math, but then throws away the value
16:16	qbg	The code is also not formatted idiomatically
16:17	Upper	tks, i will try to fix it
16:29	jjido	What are the dates of the Clojure conj? Is it finished?
16:30	FFUser	yep
16:30	jjido	was it good?
16:31	qbg	There are reports that it was very good
16:32	nickik	form what I read on twitter it was fantastic
16:32	nickik	im really waiting for the videos
16:32	jjido	nickik: thanks
16:33	qbg	Does anyone know of a syntax-rules implementation for Clojure?
16:37	rata_	I don't understand why when I compile a file for the first time in swank, it goes smoothly, but when I compile it for the second time the test (is (expression? p)) fails, but nothing has changed
16:41	gfrlog	clojure conj featured muffins
16:46	technomancy	ivey: I must have missed running into you at the conj; how goes?
16:46	ivey	technomancy: nah i wasn't there, sadly.
16:47	ivey	it's going well.
16:47	ivey	how was it?
16:52	amalloy	afternoon, jackdempsey
16:56	FFUser	ok I have a problem here
16:56	FFUser	let's say you have a fn
16:56	FFUser	and you have this: (dotimes [num (count some-list)]
16:56	FFUser	(let [elem (some-list num)]
16:57	ivey	technomancy: i spent the conj fighting with google reader XML. working on a tool to fetch my starred items and send them to readitlater, but reader API is undocumented.
16:57	FFUser	(if (= (:name elem) the-search-string) elem nill)
16:58	FFUser	the problem here is of course that this doesn't make the function return the right element
16:58	FFUser	but just the result of the last if
16:58	FFUser	in other words how do I jump out of the loop and return the result
16:58	raek	I think you are reimplementing 'some'... :)
16:59	raek	or a more specialized variant of it
16:59	FFUser	doesn't some just return true/false?
16:59	MayDaniel	,(some #{3} [1 2 3])
16:59	clojurebot	3
16:59	rata_	,(doc some)
16:59	clojurebot	"([pred coll]); Returns the first logical true value of (pred x) for any x in coll, else nil. One common idiom is to use a set as pred, for example this will return :fred if :fred is in the sequence,...
16:59	qbg	,(some #(= (:name %) "foo") [{:name "bar"} {:name "foo"}])
16:59	clojurebot	true
16:59	FFUser	see? true / false
17:00	qbg	,(some #(if (= (:name %) "foo") %) [{:name "bar"} {:name "foo"}])
17:00	clojurebot	{:name "foo"}
17:00	FFUser	oh ok
17:00	FFUser	still in general
17:00	rata_	is it possible that (class obj) returns x and (instance? x obj) return false?
17:00	FFUser	how do you deal with loops and lack of return / break statement?
17:00	amalloy	FFUser: can you make a gist or something? i can't quite follow what you're trying to ask
17:01	amalloy	FFUser: nm, i see it was answered already; i was stuck in some scrollback :P
17:01	qbg	FFUser: loop/recur would be primitives to use
17:01	raek	FFUser: loops return, unless you do a recur
17:01	FFUser	ok
17:02	FFUser	so basically if I want to end loop prematurely I can't use stuff like doseq and dotimes
17:02	qbg	Most functions that you would want are just a composition of some pre-existing ones though.
17:02	qbg	FFUser: Don't try to think in terms of loops
17:02	raek	FFUser: also, there is rarely any need to iterate over the indicies of the items and then get the item of that index
17:02	FFUser	ok but I need that
17:02	mrBliss	when you do (first (something-lazy ...)) it also ends prematurely
17:03	FFUser	I can find if item is in the coll (some) but I also need the index
17:03	FFUser	because I want to swap it
17:03	qbg	,(first (filter #(= (:name %) "foo") [{:name "bar"} {:name "foo"}]))
17:03	clojurebot	{:name "foo"}
17:03	rata_	FFUser, you need the function indexed and some
17:04	raek	FFUser: you happen to have the book "Programming Clojure"? it has an exmaple of just that
17:04	FFUser	I have a vector of maps and I want to update the map with :name = parameter
17:04	FFUser	basically replace it with a new map
17:05	raek	FFUser: ah, that chapter is available for free: http://media.pragprog.com/titles/shcloj/flow.pdf
17:05	qbg	FFUser: only the first one with (= :name parameter) or all of them?
17:06	FFUser	first one will suffice
17:06	raek	FFUser: 2.6 "Where's My for Loop", page 7
17:06	raek	or 72, if you follow the books own page numbering
17:06	FFUser	I have Clojure in Action
17:07	rata_	FFUser, (for [m maps] (assoc m :name parameter))
17:07	raek	(defn indexed [coll] (map vector (iterate inc 0) coll))
17:07	amalloy	or (map #(assoc % :name param) maps)
17:08	rata_	for is lazy, so it doesn't matter whether you want the first one or everyone... it will do you just the work you need
17:08	rata_	(map also)
17:09	qbg	(defn foo [pred f coll] (map #(if (pred %) (f %) %) coll))
17:09	rata_	is it possible that (class obj) returns x and (instance? x obj) return false?
17:09	qbg	Where pred is a predicate function for updating, and f is the update function (applies to all matches)
17:10	qbg	rata_: Do you have a case where that happens?
17:10	FFUser	:)
17:10	FFUser	I think I like the solution where you append indexes :)
17:10	FFUser	I better not time this solution though
17:10	FFUser	so many allocations it will make your head spin :D
17:14	amalloy	rata_: no, that should be impossible
17:14	qbg	(defn foo [x] (instance? (class x) x)) will throw a NullPointerException if you pass in nil though
17:15	rata_	qbg, yes, but it's difficult to make a gist of that
17:16	qbg	Due you use classloaders?
17:16	rata_	the most weird thing about it is that when I compile it for the first time it works perfectly
17:18	rata_	I really don't get it... it seems to be a problem with swank
17:18	rata_	maybe I use (ns ... (:use ...)) too much
17:21	rata_	if I compile the file twice, the (instance? x obj) doesn't work anymore
17:21	rata_	`_´
17:21	qbg	What is x?
17:22	qbg	I suspect either x or obj are being redefined and the other isn't
17:23	Nafai	Are there any tools that use nREPL yet? It's an interesting looking project.
17:23	rata_	x is Agent where Agent is (defrecord Agent [...])
17:24	qbg	Reevaluating defrecord will replace the old class with the new one
17:24	qbg	(IIRC)
17:25	amalloy	qbg: that's correct
17:25	qbg	If obj isn't being redefined, that could be it
17:26	Sweetshark	Hi all, I want to call stuff in a clojure jar from Java. I created a jar in netbeans with enclojure and it compiles just fine. I added the jar file to the project where I want to use it from. I see the symbols and everything compiles fine. However, when I run it, the call fails. With a Java jar file it works fine the way I did it. Any hints?
17:28	qbg	Sweetshark: Are you using a class generated in Clojure from Java, or are going through clojure.lang.RT to invoke a function?
17:30	rata_	qbg, and is there any way to make defrecord not to generate a new class when it already exists one?
17:31	Sweetshark	qbg: I tried both (I am now using RT). Right now I have a Java class in the clojure jar but it does not even get enter that (plain Java) method. Hang on, I have a suspicion ...
17:33	qbg	If you are going through RT, make sure the namespace has been required
17:33	Sweetshark	... puff there goes my suspicion: no, that was not the problem ...
17:34	Sweetshark	qbg: How? Do you have a link?
17:34	qbg	I've only done this once, but I just invoked require from clojure.core
17:34	qbg	(probably a better way)
17:36	rata_	is there any way to make defrecord not to generate a new class when it already exists one?
17:36	Sweetshark	well, I now have a plain java wrapper class in the clojure jar an call that ... should at least that always work?
17:37	FFUser	can someone tell me if I'm using clojurebox, where do I have to put my Irc.clj with namespace spur.irc to get it to load in repl with require spur.irc
17:37	amalloy	rata_: i don't think so. you could probably wrap the defrecord in a (when) of some kind that checks whether the class already exists?
17:38	amalloy	but then if you changed the field list, that would prevent it from getting updated on your next compile
17:44	amalloy	hey Raynes, wb. did you end up having pants leftover after the flight? :)
17:44	rata_	amalloy, I prefer that it doesn't get updated than this annoying problem with its redefinition
17:44	Raynes	amalloy: I kept them all, actually.
17:45	amalloy	well done. i left you a present on sexpbot
17:45	Raynes	I'm sick as hell at the moment.
17:45	Raynes	I'll probably get to that tomorrow if I feel like it.
17:45	Raynes	Thanks. <3
17:45	amalloy	aww
17:47	rata_	I'm looking now for a function that check if a class is defined... I don't like try and catch :P
17:52	qbg	rata_: Reflection?
17:52	rdeshpande	howdy all
17:54	rata_	qbg, do you know of a way to do it?
17:54	mister_roboto	rata_: what do you mean "defined"? if it's available on the classpath to be loaded?
17:54	rata_	I was hoping java.lang.Class/forName could help, but it throws ClassNotFound
17:54	jackdempsey	amalloy: hey there, just got internet back
17:54	jackdempsey	how's it goin
17:54	rata_	mister_roboto, if it's in the environment
17:55	mister_roboto	rata_: the JVM can't possibly tell you about classes that are not on the classpath since it doesn't magically know about them. The "environment" is the classpath
17:56	Sweetshark	qbg: got a bit further, however now i get an "Var clojure.core/refer is unbound" error. Any idea on how to fix that?
17:56	mister_roboto	rata_: i guess you could go around and open every jar you can find at the OS level and see if it contains the class :)
17:56	amalloy	jackdempsey: nothing special. i've been here since june, and this is the first time it's rained. need to buy an umbrella, i guess :P
17:56	rata_	mister_roboto, after you do a (defrecord x ...), x is in the environment
17:57	jackdempsey	amalloy: wow ok. i was going to say, is it like this? feels like a light storm
17:57	mister_roboto	rata_: ah, ok. i thought you meant regular java classes from outside your program
17:57	rata_	mister_roboto, no
17:58	rata_	mister_roboto, that'd require some magic
17:58	mister_roboto	rata_: exactly :) aren't there namespace functions to search for such bindings? (clojure newbie here)
17:59	rata_	mister_roboto, I hope so, but I don't know either
18:00	mister_roboto	rata_: does this help? http://stackoverflow.com/questions/2012651/clojure-namespace-method-to-see-defined-objects
18:03	rata_	mister_roboto, no, that's only useful for vars, not for classes
18:03	rata_	(i.e., records)
18:05	amalloy	rata_: you could check for the instance of the var you don't want redefined
18:05	amalloy	presumably if you don't want the class redefined it's because you have a var that's an instance of the old class already
18:07	rata_	amalloy, I don't even understand why the var doesn't get updated when I compile it for the second time
18:08	rata_	maybe :import should go before :use
18:10	rata_	no, putting :import before :use doesn't help either
18:12	rata_	:reload-all goes after :use? :import? :require?
18:15	Raynes	(:use my.stuff :reload-all)
18:20	rata_	yes, it seems to work now with (:use ... :reload-all) :) the only negative side-effect it's that now takes ~20 secs to run the tests, because it has to recompile everything
18:23	FFUser	time
18:23	TheAnimal	FFUser: 25.10.2010 12:24:00 +0200
18:24	FFUser	debugging clojure is challenging
18:31	zakwilson	I'm trying to upload files with compojure/ring. I'm not sure how to access the uploaded file (it appears to be a string containing the filename)
18:33	FFUser	can someone give me some pointers
18:33	FFUser	http://pastebin.com/YMSy62sZ
18:34	FFUser	I find myself losing track of what's a data structure and what's a function
18:34	FFUser	since it's all same nameing convention
18:34	rata_	FFUser, are you using emacs?
18:35	FFUser	yep
18:35	rata_	in which function do you have the problem?
18:36	FFUser	just general readability problem
18:36	FFUser	the code works fine
18:36	nickik	format your code write for one
18:37	FFUser	with java I usually keep things organised by splitting into classes
18:37	FFUser	and by limiting the number of public methods
18:38	FFUser	which limits the amount of way the classes can interact with each other
18:38	rata_	in clojure you have namespace and private and public functions
18:38	FFUser	loose coupling
18:39	FFUser	in OOP you want the classes loosely coupled and I have to somehow make my clojure programs do the same
18:40	rata_	yes, in dynamic languages you have loosely coupled objects by default (IIRC)
18:40	FFUser	not really
18:40	FFUser	it's a design thing
18:40	nickik	in clojure everything is loosly coupeld because every function (should) be indipendend
18:40	FFUser	one that my coworkers fail badly
18:40	amalloy	FFUser: not an answer to your actual question, but i notice you do the following a lot: (first (filter #(= (:name %)) coll))
18:40	FFUser	that's not what loose coupling is
18:40	rata_	FFUser, why?
18:41	rata_	FFUser, what's loose coupling for you?
18:41	amalloy	this can be replaced with (some (comp #{target} :name))
18:41	amalloy	(where target is the name you're looking for)
18:42	FFUser	in OOP it is when classes (larger unit of functionality than function) have limited number of
18:42	nickik	@amalloy wanted to say that to
18:42	nickik	*too
18:42	FFUser	exposed methods through which other classes can influence them
18:42	FFUser	in clojure every function can pretty much call any other function usually
18:42	rata_	FFUser, that's not true if you use namespaces and private functions
18:43	nickik	define data and some functions on those data then put that stuff in a namespace and define some of the functions privat and some public
18:43	FFUser	thanks ammaloy
18:43	rata_	also, you definition of loose coupling resembles more the one of encapsulation
18:43	nickik	true
18:43	FFUser	they are related concepts
18:45	nickik	just think of it like this in FP a Class is a namespace. Then you can define private and public functions with defn or defn-. Its the same as in java just without protected.
18:46	rata_	FFUser, they don't seem to be related: http://en.wikipedia.org/wiki/Loose_coupling
18:47	FFUser	nickik: in that case I'd easily split my code into 4 namespaces with 3 functions each
18:47	rata_	loose coupling is the use of interfaces in Java
18:47	nickik	i agree that the are related if you encapsulate a object the write way its easy to have loose coupling
18:47	FFUser	if you asked me to craft classes out of it
18:48	FFUser	yes that's what I meant
18:49	rata_	FFUser, then do that if you want your code more organized
18:49	FFUser	seems like it
18:49	FFUser	I was also looking for some kind of coding convention
18:49	FFUser	like in C++ you have hungarian notation
18:50	mister_roboto	FFUser: Hungarian notation is for encoding types in the name. functions are just functions though
18:50	nickik	@FFUser that seams to be alot. namespaces a usually a little bigger for conventions you can look at http://www.assembla.com/wiki/show/clojure/Clojure_Library_Coding_Standards
18:50	zakwilson	Loose coupling means that if A doesn't need to know about B, it doesn't. How you communicate that in your code is up to you, though namespaces do provide a mechanism to make it easy.
18:51	FFUser	mister roboto: clojure doesn't have types but it has vars that are bound to data, vars bound to FNs and vars bound to mutables (atoms, refs)
18:52	zakwilson	Clojure has types. They're attached to the data, not the variable.
18:52	mister_roboto	zakwilson: loose coupling means something a bit stronger than that. it means that if A uses B, it doesn't depend on how B is implemented. i think that falls out of FP automatically if your function is referentially transparent
18:52	FFUser	it was my idea to make different name prefixes for these 3 kinds
18:53	nickik	i would do that look into :"Follow clojure.core's example for idiomatic names like pred and coll" in the document i linked
18:54	nickik	in general: functions should read like verbs and data should read like nouns
18:54	FFUser	yeah I use same thing in java
18:55	FFUser	sometimes these names can be hard to craft though
18:55	rata_	mister_roboto, that isn't it... it that if A uses B, probably you mean that A uses an interface that have the methods you need
18:55	mister_roboto	FFUser: why would you need a special idiom for mutable var names when you already have to use a special form to access them? doesn't that tell you everything?
18:55	FFUser	making function name verb-like but not too vague often results in extremely long names :D
18:56	FFUser	it tells me everything when reading correct code
18:56	mister_roboto	rata_: the only reason interfaces enable loose coupling is BECAUSE they make it impossible to depend on the implementation
18:56	FFUser	the problem is forgetting to use the special form
18:56	FFUser	the compiler won't warn me
18:57	mister_roboto	rata_: the only visibility you have to the "used" class is the "protocol"
18:57	rata_	yes, that is
18:58	rata_	OOP is about procedural abstraction
18:58	mister_roboto	rata_: oops is about many things. encapsulation, data hiding, inheritance, locality of data and methods which operate on the data, etc
18:59	mister_roboto	s/oops/OOP/
18:59	sexpbot	<mister_roboto> rata_: OOP is about many things. encapsulation, data hiding, inheritance, locality of data and methods which operate on the data, etc
18:59	rata_	I think a good read about that is http://www.dcc.uchile.cl/~etanter/ooplai/adt-oo.html
19:00	rata_	I don't think encapsulation, data hiding, inheritance and locality of data are much related to OOP in general... they are related to some kinds of OOP implementations
19:01	mister_roboto	rata_: http://en.wikipedia.org/wiki/Object-oriented_programming like I said, OOP is about many things. sure you can leave out the bits you don't want to talk about but they are still part of OOP
19:01	rata_	FFUser, I think you'll enjoy this article (by Stuart Halloway): http://www.nofluffjuststuff.com/blog/stuart_halloway/2009/08/rifle_oriented_programming_with_clojure
19:02	nickik	the three thinks alan kay said are the base of OO are: Encapsulation, Subtype polymorphism, Object inheritance
19:04	FFUser	too bad people I work with only use Encapsulation and even that one badly
19:04	rata_	nickik, then every language that's based on delegation instead of inheritance isn't object-oriented?
19:04	rata_	I don't think so
19:05	nickik	no, I'm just pointing out what the original definition is. Today everthing is diffrent.
19:06	nickik	FP isn't the same as it was 40-50 ago.
19:06	FFUser	imagine a bunch of void return methods on a single class named "processSomething" with no arguments, which load stuff from DB and then mutate half a dozen huge java beans, some dealing with state (data) storage and some dealing with UI state
19:06	rata_	nickik, thus I think the core of OOP is message passing and procedural abstraction
19:06	mister_roboto	rata_: i think the key thing is that some features of traditional OOP, like reuse through inheritance only, is bad. so delegation is preferred. however, even a modern OOP like java and .NET has inheritance.
19:07	rata_	FFUser, that's gonna be difficult to test for sure
19:07	FFUser	I am tasked with adding functionality to such existing projects
19:07	nickik	thats the problem with descutions like this everybody means something else when he sais OO or FP
19:07	FFUser	I have absolutely no idea which beans any of these functions affects under which conditions
19:08	rata_	mister_roboto, that's not modern OOP... also inheritance and classes is just one way to implement OOP
19:08	mister_roboto	FFUser: you mean like adding new functionality without changing the existing code? that kind of code isn't testable
19:09	FFUser	adding new business logic into existing UI
19:09	FFUser	well JSFs
19:09	FFUser	and I don't understand the business logic already implemented, it's domain specific and you need experts to make specifications
19:09	mister_roboto	rata_: what is a modern OOPL that you are talking about then that doesn't have inheritance, for example?
19:10	FFUser	anyway, clojure is like my vacation from work
19:10	FFUser	and work is my nightmare
19:10	mister_roboto	FFUser: that's a bad spot to be in, but all too common. can you modify the existing code to start injecting dependencies?
19:10	rata_	JavaScript doesn't use inheritance... Scala uses inheritance and is more modern than Java or C#
19:10	FFUser	don't have enough hours allocated to refactor code
19:11	mister_roboto	rata_: javascript uses prototype based inheritance
19:11	FFUser	bonus points: people who did this call me an academic when I talk about OOP. Needless to say, none of them have an actual degree in CS
19:12	rata_	mister_roboto, that's not inheritance, that's delegation
19:13	rata_	this is an interesting topic, but I'm going now to eat something... see you later guys :)
19:13	mister_roboto	rata_: prototype inheritance is still reuse by depending on implementation of the prototype
19:14	mister_roboto	rata_: i suggest reading about javascript and inheritance
19:14	nickik	@FFUser i'm doing boring database IO with ASP classic thats no fun either
19:15	rata_	one has to be cautious when reading about those topics... there's a lot of people (even academics) out there that mix up ADTs and objects
19:15	mister_roboto	FFUser: i know exactly the kind of code you're dealing with. if you can't refactor, at least try to write some good tests before modifying it
19:15	mister_roboto	FFUser: although it's damn hard to even test such code
19:16	mister_roboto	FFUser: everything is a giant integration test - can't tease apart the components in a big ball of mud
19:16	rata_	if they confuse ADTs and objects, to mix up inheritance and delegation would be even easier
19:17	FFUser	I'm not optimistic about the future of dealing with other developers
19:17	nickik	so good night i have to get up early to do some more boring stuff at work :)
19:18	FFUser	in my coutry about 10% of developers have BS in CS, 45% have associate's degree(I think that's what it's called) in CS and 45% have high school education
19:21	mister_roboto	rata_: http://www.cs.rit.edu/~atk/JavaScript/manuals/jsobj/ javascript prototype inheritance is true inheritance. you aren't holding onto a prototype handle and delegating to it, unless you also count c++ vtables as holding on to ancestor references and doing delegation
19:21	FFUser	time
19:21	TheAnimal	FFUser: 25.10.2010 01:22:18 +0200
19:28	mister_roboto	FFUser: and in every other country, more and more development is outsourced to countries with lots of degreed programmers who, unfortunately, just started programming professionally on the program you're giving them :)
19:31	FFUser	It's terrible here. And the CS faculty had 180 spots, 360 applicants and you needed to be a mixed C grade/D grade student to get in.
19:31	FFUser	a lot of them drop out and work as programmers
19:32	FFUser	now imagine dropouts who had high school math graded C work as programmers
19:33	FFUser	anyway, enough griping about the state od development around here
19:33	FFUser	good night
20:03	yayitswei	Is there a way to splice a list into arguments (what the splat operator in Ruby does) without using a macro? I'm trying to turn a list into arguments for recur.
20:04	amalloy	apply
20:05	amalloy	though i'm not sure that works for recur. recur is probably a special form
20:05	amalloy	,(doc recur)
20:05	clojurebot	Gabh mo leithscéal?
20:05	yayitswei	it is a special form
20:05	yayitswei	so I don't think I can use apply
20:05	amalloy	no, you can't
20:06	jackdempsey	is it a variable list? can't destructure it
20:06	amalloy	i think the usual way to do this would be destructuring
20:07	amalloy	,(loop [[a b] (range)] (if (= 10 a) b (recur (map + [a b]))))
20:08	clojurebot	Execution Timed Out
20:08	amalloy	er, that's not what i meant
20:08	amalloy	,(loop [[a b] (range)] (if (= 10 a) b (recur (map inc [a b]))))
20:08	clojurebot	11
20:10	amalloy	yayitswei: does that help?
20:10	yayitswei	amalloy: still reading it :)
20:13	yayitswei	amalloy: what's the (range) for?
20:13	amalloy	just a convenient initial value for the loop
20:13	amalloy	sets a=0, b=1
20:14	yayitswei	oh i see
20:15	yayitswei	so the recursive function should take one argument, a list, instead of arbitrarily many
20:16	amalloy	right
20:16	amalloy	and then pull apart the list however you want
20:17	yayitswei	amalloy: got it-- thanks!
20:17	amalloy	or, have your arbitrarily-many function public, internally implemented as a loop around a list
20:17	yayitswei	if I really wanted to make it a
20:17	yayitswei	oh yeah that's what i was just going to ask
20:23	rata_	mister_roboto, I think that link shows how to simulate inheritance in javascript
20:23	rata_	many features of class-based languages, such as inheritance, can be simulated in a delegation-based language
20:24	rata_	http://en.wikipedia.org/wiki/Prototype-based_programming
20:24	mister_roboto	rata_: no, it shows how inheritance DOES work in Javascript. it's just showing how to you structure that sort of inheritance hierarchy, comparing Java to Javascript, where the first is class-based inheritance and the second is prototype-based inheritance
20:24	mister_roboto	rata_: that's just how it works. look up constructors and prototypes in javascript. that's what they are for
20:25	rata_	mister_roboto, look at the prototype-based programming article in wikipedia
20:26	mister_roboto	reading
20:28	mister_roboto	rata_: ok, so i'll buy that it's an ambiguity :) it's not like typical delegation where you are explicitly delegating calls to some delegate, however. you only reference the prototype in javascript typically to set up the prototyype chain so this inheritance of behavior happens automatically when you construct an object
20:29	mister_roboto	rata_: the rest of the time you just use the instance directly. if you still want to call that delegation, it seems to me that it's j ust a non-useful blurring of concepts
20:31	rata_	mister_roboto, that's why I said that use of prototypes is an emulation of inheritance :)
20:31	rata_	also the OOPLAI book (a work in progress yet) explains the differences between class-based and prototype-based languages very well IMHO http://www.dcc.uchile.cl/~etanter/ooplai/
20:32	rata_	do you have read PLAI?
20:32	mister_roboto	rata_: ok ok, i see your point. if the language is hiding the "delegation" from you when you are accessing an instance behavior, it seems to me no different than c++ hiding it by internally accessing the vtable
20:32	mister_roboto	rata_: i mean insofar as discussing whether a language has "inheritance" proper
20:33	mister_roboto	rata_: it's just an implementation detail. to call it "emulated" doesn't enhance understanding of what it is or does
20:34	mister_roboto	rata_: what does inheritance mean if not having behavior and properties automatically propagate through the chain of dependent objects?
20:34	rata_	it's not hiding the delegation at all... it's just using it to implement inheritance-like constructs
20:35	mister_roboto	rata_: when i call jsobject.someproperty, i don't know if it's a local or coming from the prototype
20:35	mister_roboto	rata_: that's not hiding it?
20:35	rata_	that's not hiding it... that's how delegation works
20:36	rata_	inheritance definition depends on classes
20:36	mister_roboto	or setting up the prototype chain
20:36	mister_roboto	my example... is that not hiding the delegation?
20:36	rata_	yes, that's not hiding the delegation
20:37	mister_roboto	rata_: ok, then i guess we cannot agree on that point
20:38	rata_	if object jsobject doesn't know how to interpret the message 'someproperty', then it's going to delegate that message to other object
20:38	rata_	we can't agree on that point
20:38	mister_roboto	rata_: just like the c++ object delegates via the vtable. it's a language implementation detail of how to locate hte property
20:38	mister_roboto	i totally agree with what you just said
20:39	rata_	the important difference between them is that delegation occurs between objects and inheritance happens between classes
20:39	rata_	the vtable is an implementation detail
20:47	mister_roboto	this is actually kind of interesting because earlier you were claiming that inheritance isn't part of OOP but you seem to be saying that class-based OOP is actually the only way to do inheritance
20:50	rata_	yes, I was saying inheritance isn't part of OOP, but part of class-based OOP
20:52	amalloy	ummmm, no offense guys, but could you take this discussion to #oop or something? i don't want to miss any clojure-related messages in the flood
20:52	mister_roboto	sorry amalloy, you're right
20:52	rata_	sorry amalloy
20:53	ymasory	why is there no "lein run"? what am i missing?
20:53	mister_roboto	my final statement is only that i think it is pointless to draw a line between "true" and "emulated" inheritance. i will shut up now
20:54	amalloy	ymasory: how does lein know what function you want to run? or do you want it to start up a repl and then eval everything in your project, maybe?
20:55	rata_	just-in-time for the clojure-related question :)
20:55	ymasory	amalloy: not sure if there's a dedicated start point in clojure. sbt runs the first main function it can find with the matching signature
20:56	ymasory	it seems like a pretty slow procedure to say lein repl and then type out a start point
20:57	amalloy	ymasory: you can specify the main function in project.clj, and then when you java -jar the result of lein jar, it should call that function
20:57	ymasory	thanks
20:57	raek	there is some feature to set the starting namespace. I do not know if that also automatically requires that namespace
20:59	Adamant	clojurebot: do you have a neural net processah lahk Ahnold?
20:59	clojurebot	Huh?
20:59	mister_roboto	amalloy: how does that work? does it put that function inside a main()?
21:00	amalloy	mister_roboto: every clojure function turns into a java class. i imagine it renames the main class's function main, and it certainly puts an entry in the jar manifest
21:00	raek	if you add :main your-namespace-here, the repl will start in that namespace
21:01	raek	ah, and there's also :repl-init-script
21:02	amalloy	raek: cool. does that affect swank too?
21:03	raek	no idea :)
21:03	mister_roboto	if I had to decide between using lein or cake, is there any clear advantages to choosing one? i haven't used them, only did some reading and they seem to do the same thing
21:05	rata_	raek, where do you put that ":main your-ns"?
21:05	amalloy	mister_roboto: one nice feature of cake is that it will keep jvms running in the background to speed up launch time of all cake tasks
21:05	amalloy	otoh, if you're strapped for RAM, it's probably inconvenient to keep killing those
21:06	raek	ymasory: one common way seems to be to only have function and constant definitions at the top level of the source files. (i.e., when you load a file, the application doesn't start.) then, you provide a -main function to start your application.
21:06	raek	rata_: in your project.clj file
21:07	raek	but still, when launcing the repl you have to type stuff
21:07	mister_roboto	amalloy: so if you're not tight on RAM then cake has the lead :)
21:07	rata_	raek, in (ns ...)?
21:08	amalloy	that's been my experience. but lein is a little older and more stable/tested. they also have incompatible plugin architectures, so if someone's written a lein plugin you really want...
21:08	amalloy	but for the most part they're compatible so it should be easy to switch if that happens
21:08	raek	rata_: I'm sorry... what in (ns ...)?
21:08	amalloy	rata_: no, in the project.clj file at the top level of your lein/cake project
21:09	rata_	raek, that ":main your-ns"
21:09	rata_	ah ok
21:09	rata_	sorry
21:09	rata_	read only the first msg
21:11	raek	ok, I can confirm that setting the main namespace will cause that namespace to be loaded when you start the repl
21:12	raek	so, you could see the main namespace as a startup script, if you want to
21:34	mister_roboto	how do i make an entity bean using cake? (kidding!) is it a fairly typical thing to use any old editor (emacs or whatever) to create the code and then use lein/cake to package it for release?
21:34	hiredman	yes
21:36	amalloy	mister_roboto: yep, pretty normal. CCW users might have their own thing, but a lot of us use emacs/cake
21:37	mister_roboto	amalloy: so far i only used CCW to build fairly small programs that i just ran at the repl by typing it in. i really need to go to the next step of having a full automated build process and i cake seems to be a very good choice
21:38	amalloy	it certainly is a good choice. but laurent might have something that integrates better with eclipse, i don't know
21:39	mister_roboto	amalloy: when i use CCW, i tpically just execute the clj file and leave the resulting repl running. then i've been copy/pasting new code down into the repl rather than killing it and re-running the script file(s). this sounds clumsier than emacs with its repl integration (Swank?) but i haven't tried that approach
21:41	hiredman	thats fine for dev
21:41	hiredman	but when you deploy you build a jar
21:52	mister_roboto	hiredman: right. i've been doing java development for too many years now :)
21:53	mister_roboto	hiredman: maven and ant before that. need something for clojure now and i guess it's gonna be cake
21:59	amalloy	mister_roboto: cake and lein are both built on top of maven
22:00	amalloy	eg, lein/cake pom creates a pom.xml file you can manage with maven if you prefer
22:01	mister_roboto	amalloy: that's good in that i'll understand what's going on underneath and i can point it to our in-house artifactory repo for the dependencies. however, i think all the management looks like it will be best done via project.clj
22:11	ymasory	why can't clojure put in the "recur" bit by itself? at least in some simple cases?
22:16	somnium	ymasory: there are a few threads on the mailing list about it. the principle reason seems to be that since it would only be possible in some cases, better to make it explicit everywhere.
22:17	somnium	ymasory: plus you can always use scheme :P
22:19	ymasory	gotcha. thanks. seemed a little funny in the simple cases
22:22	ymasory	can i get the previous line back in the repl?
22:28	mister_roboto	install rlwrap like here: http://programmingzen.com/2010/07/13/how-to-setup-clojure-from-scratch/ or use "cake repl" like here: http://github.com/ninjudd/cake
22:29	mister_roboto	ymasory: maybe there's an easier way but rlwrap worked well for me. a standalone repl is annoying without history
22:33	ymasory	no kidding, thanks
22:35	ymasory	while i'm at it. why doesn't clojure allow forward-references to functions? other lisps do
22:38	mister_roboto	ymasory: you mean like this or something else? http://en.wikibooks.org/wiki/Clojure_Programming/Concepts#Mutual_Recursion
22:40	somnium	ymasory: you can use declare for forward declarations
22:41	ymasory	somnium: do other lisps require forward declarations?
22:41	somnium	ymasory: I don't think so
22:42	somnium	I don't know how CL does it, but I do think R6RS scheme really got that part right (scoping of top levels)
22:42	somnium	still, adding (declare ...) isn't so painful
22:45	ymasory	painless as C :)
22:49	somnium	ymasory: aw, surely Clojure isn't in the same league as C in terms of inflicting pain on programmers :)
23:36	ymasory	what does the & mean in function signatures?
23:37	dsantiago	It means any number of additional arguments, which will all be put into the name given after the & as a list.
23:38	ymasory	ah thanks