#clojure – 2011-02-10

2011-02-10

00:03	mec_	is there a good way to map subvec across a vector for windowing?
00:08	tomoj	mec__: what are you going to do with the windows?
00:08	tomoj	I mean, do you really need vector windows?
00:09	tomoj	vs something like ##(partition 3 1 [1 2 3 4 5 6]) ?
00:09	sexpbot	⟹ ((1 2 3) (2 3 4) (3 4 5) (4 5 6))
00:12	mec__	thats what i want, but i figured subvec would be a lot faster if I specifically had a vector
00:15	tomoj	well..
00:17	tomoj	probably depends on window size and what you do with the windows
00:17	tomoj	for window size 3, it looks like partition is faster at generating the windows
00:18	tomoj	while for window size 10, subvec seems faster
00:19	tomoj	map is variadic, so you can (map #(subvec v %1 %2) x y) where x and y are seqs of the appropriate indices
00:20	mec__	oh didnt think of that at all, thanks
00:21	tomoj	oh, wow
00:22	tomoj	(partition n 1 v) is O(n) for fixed v
00:23	mec__	how is that possible? it creates a seq that touches the whole thing
00:23	tomoj	I mean, ignoring that factor
00:24	mec__	its O(n) or O(count v)
00:24	tomoj	I think (partition w 1 v) is O(n*w) if v has n elements
00:24	mec__	ah
00:24	tomoj	'n' was a bad choice for window size
00:24	tomoj	subvec has a constant (or log32?) factor instead of w, I think, but for small w it's worse
00:25	tomoj	constant according to subvec's docs
00:26	tomoj	can you do better than O(n*w) on seqs in general for the step=1 case?
00:28	mec__	i wouldnt think so, but subvec is deffinitly constant
00:32	tomoj	well, you can generate a seq of the windows in O(n) with something like (->> s (iterate next) (take-while identity) (drop-last (dec w)) (map #(take w %))), but that might be cheating compared to (partition w 1 s)?
00:32	amalloy	tomoj: constant according to the source too. it just creates an object storing the parent vector and the indices, and does the appropriate translated nth lookups in the parent when you access a subvec element
00:35	tomoj	I've been thinking lately about doing something like that for permutations
00:36	tomoj	sound feasible?
00:37	mec__	Hard to say if it would be any faster, wouldnt you need a map for the old to new indices?
00:37	tomoj	yeah, but looking up the new index is practically constant while creating a new vector from scratch is O(n), yes?
00:38	mec__	true but would creating the map be O(n) anyway?
00:38	tomoj	amalloy: thanks, I hadn't realized that's what subvec did, I'll look there for inspiration
00:38	tomoj	well, I only have one permutation
00:38	tomoj	and its inverse
00:38	tomoj	and need to apply them many times to many vectors with thousands of elements
00:38	tomoj	so I can have the maps already sitting around beforehand
00:41	tomoj	ooh, even with more permutations (say, hundreds), I can memoize all the combinations to avoid multiplying the log32 vector access
00:54	tomoj	oh, now I remember the problems I ran into.. it's really simple if you never change a permuted vector, not so simple if you do
00:55	tomoj	maybe I can get away with only implementing the read-only stuff for a while..
01:04	no_mind	how do I produce html using compojure. When I call (html0 function, I get a compile time error
01:04	no_mind	(html)
01:04	no_mind	.(html)
01:10	puredanger	let's just hypothetically say that I have a deep aversion to every Java logger ever invented and that I want to do some logging from a Clojure app
01:10	technomancy	puredanger: it's simple, just use this logging abstraction framework
01:10	puredanger	is there a Clojure lib that does very basic logging? (not c.c.logging)
01:11	technomancy	you can plug in any logging implementation or even other logging abstraction frameworks!
01:11	puredanger	technomancy: <headdesk>
01:11	technomancy	(just ignore the fact that there are only two logging implementations in existence and at least three logging abstractions)
01:12	puredanger	technomancy: I see you share my love of Java logging f/ws
01:13	khaliG	anyone familiar with miglayout? i wish to use the do-layout function, but the compiler says java.lang.IllegalAccessError: do-layout does not exist
01:14	khaliG	oh i see it's an internal function
01:34	tomoj	would a feature that allowed you to delegate all unimplemented methods in a deftype to one of its fields be evil? not suggesting this feature, just want it now but suspect that it's evil
01:39	amalloy	tomoj: that sounds exactly like extending a class: implementation inheritance
01:39	amalloy	so i suspect the two are equally evil
01:41	tomoj	when you say it that way this sounds even more evil
01:50	no_mind	how can I install enlive using lein ? It gives me an error for dependency on org.apache.maven:super-pom:jar:2.0
01:52	rata_	can you search for something like blah in emacs history?
01:54	tomoj	no_mind: paste the entire output somewhere (not here)
01:55	amalloy	tomoj: it was not an accident :)
02:17	sritchie	hey all -- I've got a first draft of a function to walk a matrix with a window size and a step of 1, returning all window x window submatrices. would anyone be up for taking a look?
02:17	sritchie	https://gist.github.com/5b33bae6bb3e28b7f815
02:18	sritchie	the output is correct, but i suspect there's a cleaner way of doing this
02:22	amalloy	sritchie: plus reduce and conj aren't lazy
02:22	raek	sritchie: check out the torus-window function: http://www.bestinclass.dk/index.clj/2009/10/brians-functional-brain.html
02:23	sritchie	this line: "Everytime we are applying rules to a cell we need to consider 9 cells in total: The target and his 8 neighbors." is exactly what I was going for
02:23	sritchie	awesome, thanks, raek
02:24	amalloy	except it sounds like you don't actually want a torus
02:25	raek	then using a window function like this might work: (defn window [coll] (partition 3 1 coll))
02:26	raek	the number of windows will then be (- (count coll) 2)
02:27	sritchie	this is for a nearest neighbor analysis, so I do need to walk in both dimensions, with the window
02:27	sritchie	getting a lazy sequence of 2d vectors, ideally
02:27	sritchie	raek: that'll let me walk along 1d, right?
02:28	raek	yes, but the 'step' function uses it twice to get 2d
02:29	raek	hrm. also consider using 'for' instead of 'map' + anonymous function
02:29	raek	IMHO the code tends to be easer to read then
02:30	sritchie	raek: okay, good advice
02:30	amalloy	raek: agreed, i was gonna put something together with for
02:31	sritchie	raek: for looks a lot clearer, that's great
02:32	sritchie	is torus window lazy, here?
02:32	raek	yes
02:32	raek	partition is lazy
02:33	rata_	sritchie: I haven't read the blog post yet, but this works for me: (mapcat (comp (partial apply map vector) (partial map (partial partition w 1))) (partition w 1 m))
02:34	sritchie	rata_: ah, so that gets rid of my reduce conj step
02:35	rata_	it does more than that I think
02:35	amalloy	brehaut: another one for the point-free brigade, it seems
02:36	sritchie	rat sorry, I meant mapcat got rid of that
02:36	rata_	it's completely lazy and it doesn't use count
02:36	rata_	yes
02:37	raek	the map vector step can't be lazy
02:37	rata_	amalloy: what's the point-free brigade? those that don't like/use java interop?
02:38	rata_	raek: but map is lazy
02:38	amalloy	rata_: heh, no. point-free is a style that is popular with haskell programmers. (partial (comp foo bar) 10) rather than #(foo (bar 10 %&))
02:39	rata_	ah hahaha ok =)
02:39	amalloy	ie, "talking" about functions and gluing them together without mentioning their actual params
02:39	rata_	yes, I prefer that style... that % looks dirty
02:39	raek	you have something like (1 2 3 4) and turn it into [1 2 3 4]?
02:40	amalloy	i like point-free myself, and brehaut and Raynes are always teasing me that i should try haskell
02:40	rata_	raek: no, that's vec
02:40	rata_	for what I know about haskell, I like it... but I haven't done a project in haskell yet
02:41	amalloy	same
02:42	amalloy	$heval take 10 $ let fib = 1 : 1 : zipWith (+) fib (tail fib) in fib
02:42	sexpbot	⟹ [1,1,2,3,5,8,13,21,34,55]
02:42	amalloy	rata_: brehaut tells me this is how all the cool kids generate fibonacci numbers
02:42	rata_	amalloy: yes, that's pure beauty =)
02:43	rata_	I loved it the first time I saw it
02:43	amalloy	chuckle well, i'm off to bed. i'll try to dream of parens instead of $ and .
02:44	rata_	hahahaha
02:44	rata_	good night amalloy
02:44	rata_	do you guys know what's the best way to do ajax with clojure?
02:45	rata_	best intended in a very subjective way of course
02:46	Scriptor	rata_: I prefer to just keep my server code strictly separated, jquery for the ajax calls, and maybe have a clojure handler return json
02:49	rata_	Scriptor: so make the website in html+javascript and maybe call some clojure fns?
02:49	Scriptor	er, the front-end is in html+js, the backend would still use clojure
02:50	Scriptor	so yes, just send an ajax request to a url and have that url be tied to whatever callback you want
02:51	rata_	have you any examples at which I could give a look?
02:51	Scriptor	not off the top of my head, and also not really with clojure
02:52	Scriptor	but you don't have to learn much, just how to send a request using javascript and how to return json in clojure
02:53	Scriptor	since otherwise a request is still just a request
02:54	rata_	yes... do you know where I can learn those things?
02:55	raek	in ring, you can just respond with {:status 200, :headers {"Content-Type" "application/json"} (clojure.contrib.json/json-str some-data)}
02:55	raek	rata_: have you done server-side web programming in clojure?
02:56	rata_	no... I know a bit of html and that's all
02:56	Scriptor	rata_: how much programming experience do you have in general?
02:57	rata_	~8 years
02:57	clojurebot	Pardon?
02:57	raek	~test
02:57	clojurebot	lastest is 1135
02:57	Fossi	:D
02:58	rata_	I do "scientific" programming mainly (I don't know if that's a good name for what I do)
02:59	Scriptor	rata_: start off with some basic web apps using compojure or something like that, then start learning javascript and a little jquery
03:00	Scriptor	or whatever js framework you want
03:00	rata_	ok... do you use compojure?
03:00	Scriptor	not personally
03:00	rata_	what do you use?
03:00	Scriptor	don't really use clojure, really :p
03:00	raek	I usually use Ring + Moustache + Enlive
03:00	Fossi	yeah, any combination should do actually
03:00	rata_	Scriptor: ah ok =)
03:01	raek	Ring + Compojure + Hiccup is another very common combo
03:01	rata_	Scriptor: which language do you use?
03:01	raek	web programming in clojure is very modular
03:01	rata_	raek: what's moustache and enlive for?
03:01	Scriptor	rata_: mainly php and python, but I've been learning lisp on the side
03:01	rata_	ok
03:01	Scriptor	the principles of web dev are often the same
03:01	raek	moustache is for routing (mathcing URLs and HTTP methods), enlive is for html templating
03:02	raek	actually, enlive can do html scraping too
03:02	rata_	raek: I thought ring was for routing
03:02	raek	it reads html from a file into a clojure datastructure, lets you transform it and turn it back into a html stream again
03:03	brehaut	rata_: ring is the HTTP to clj to HTTP translation layer
03:03	raek	ring is the standard for what a request and a response looks like
03:03	Fossi	it's so awesome that clojure has ring
03:03	raek	it comes with a web server that implements that contract
03:03	Fossi	java containers are a mess :>
03:07	rata_	so, if I get it right, you put the html+js part in using enlive?
03:08	raek	if the html never changes, you don't pass it through enlive
03:08	brehaut	raek: enlive is a much more strongly seperated `templating system` than is typical
03:08	brehaut	you put your html and js into an html file
03:09	raek	(i.e. the web site uses ajax to transfer all data)
03:09	brehaut	and then you use ring to update that file for a particular resource
03:11	brehaut	that was at rata_ sorry
03:12	rata_	mmm... then if I'm using ajax I'm not going to need enlive raek?
03:13	brehaut	rata_: ajax is a pretty vague term, but, as a term it usually refers to the client side program
03:13	brehaut	you dont 'need' anything on the server to do ajax
03:14	brehaut	rata_: you just have to write some route handlers that return data in a format your client side can handle (typically json these days, originally xml)
03:14	raek	rata_: that can be true.
03:14	raek	depends on how you do it.
03:15	rata_	brehaut: but using ajax you can ask the server to compute something and then render it in the webpage without have to refresh it, right?
03:15	brehaut	rata_: correct
03:15	rata_	and route handlers are clojure fns?
03:16	brehaut	yeah; you use either moustache or compojure to map a url to a fn
03:16	brehaut	that stage is route handling
03:17	rata_	ok, so the client request the result of a computation asking for a url?
03:17	rata_	and then renders it within the same page
03:17	brehaut	rata_: it doesnt as for the result of a computation; it asks for a resource - all urls map to resources in http.
03:17	brehaut	dont think of it as an RPC system
03:18	brehaut	theres two primary methods for accessing a resource: GET and POST (there is also PUT and DELETE, but for a variety of reasons they are not as common)
03:18	brehaut	GET purely gets; its an idempotent action
03:18	brehaut	POST is server specific
03:19	rata_	resources sounds like there something in the server already... I need to compute something based on what the client put in the forms
03:19	brehaut	rata_: they dont have to be
03:19	rata_	*there's
03:19	rata_	ok
03:19	rata_	so I do a GET or POST and get the result I need
03:19	brehaut	rata_: does the result of the calculation ever change?
03:20	rata_	no, but there are infinite possible inputs
03:20	brehaut	sorry, i wasnt clear.
03:20	rata_	(not sure if infinite, but huge anyway)
03:20	khaliG	the indenting behaviour of slime is really annoying
03:21	khaliG	it keeps trying to push my fns all the way across the screen
03:21	brehaut	rata_: if you pass the same inputs to the fun, will it always produce the same result
03:21	rata_	yes
03:21	brehaut	then a GET on a resource with query parameters is completely fine
03:21	brehaut	which is nice because its super easy
03:21	rata_	=)
03:23	rata_	it's not a problem that the query parameters are long strings?
03:23	brehaut	how long?
03:24	brehaut	from memory you can safely assume 1024 characters for your url on any compliant HTTP server or proxy
03:24	rata_	it can be longer than that I think
03:25	brehaut	sad; safer to go with a post then
03:25	brehaut	even though you'd proably never run into it in the real world
03:26	rata_	there's no size limitation with post then
03:26	brehaut	rata_: have you got a non-ajax version of the web app going ?
03:26	rata_	no... should I do that first?
03:26	brehaut	rata_: nope, post you send the arguments in the body of the request
03:26	brehaut	yeah i would recommend it
03:27	brehaut	ajax builds on all the basic ideas
03:27	brehaut	try http://mmcgrana.github.com/2010/07/develop-deploy-clojure-web-applications.html
03:27	brehaut	as a tutorial
03:27	rata_	thanks =)
03:27	brehaut	heres the thing: the difference between an 'ajax' resource and a 'web page' resource is the content type it sends back
03:28	brehaut	you can legitimately have a page say, /hello/name
03:28	brehaut	that returns "<html><h1>Hello, name!</h1></html>"
03:29	brehaut	for a web browser (or default)
03:29	brehaut	and then returns "{"message":"Hello, name!"}" for 'ajax' requests
03:30	rata_	so it's easy to ajaxify a non-ajax webpage?
03:30	brehaut	yes
03:30	brehaut	theres no reason your ajax version cant just consume the HTML version
03:30	rata_	ok, thanks a lot =)
03:31	brehaut	and then just find the appropriate nodes in the DOM
03:31	brehaut	no problem
03:31	tomoj	wat
03:31	brehaut	tomoj: ?
03:32	tomoj	were you recommending generating html, then parsing that to generate json?
03:32	brehaut	tomoj: not recommending it per se
03:33	tomoj	ok
03:33	brehaut	i just didnt want rata_ to think that ajax was somehow magical or something special
03:33	Fossi	it's pretty easy and nice to have two output methods for your data though
03:35	rata_	so then I'll have to make my fns to return json instead of html?
03:35	brehaut	yeah you can switch on the accepts header, or theres a header that libs like jquery add to ajax 'X-Request-With: ajax" i think?
03:36	brehaut	rata_ its really easy though; ring will provide you a request map which will have a key :headers which maps to a map
03:37	brehaut	that map will likely have an :accepts header, and maybe :x-requested-with
03:38	rata_	but the main difference is you use enlive to return html, but not for json
03:39	Scriptor	rata_: right, json is pretty easy to generate, you can find json libs online
03:40	brehaut	c.c.json or clj-json will take standard clojure datastructures and generate json string for you
03:40	rata_	ok, thanks again
03:41	brehaut	rata_: mmcgrana has another tutorial of interest http://mmcgrana.github.com/2010/08/clojure-rest-api.html
03:41	brehaut	shows you how to do json-responses
03:42	rata_	I'll read it too
03:42	tomoj	huh. I think if I switch to clj-json from clojure-json I'll have to rename generate-string and parse-string to encode and decode
03:43	brehaut	win :)
03:44	tomoj	eh, I only considered it because it says "fast", but clojure-json isn't even close to a bottleneck anyway
03:44	brehaut	i wonder if i should change necessary-evil to use the same terms as clj-json before anyone actually starts depending on it
03:45	brehaut	parse and unparse are a bit clunky
03:46	tomoj	I like em better than those long things with their "-string"s sticking out
03:48	brehaut	i guess
03:48	brehaut	not particularly nice either way
03:52	meltingwax	hi
03:52	brehaut	night
03:57	meltingwax	is closure compatible with common lisp libraries?
03:58	opqdonut	no, it's a different language on a different platform
04:00	meltingwax	what if i really needed it
04:01	ejackson	you can try prayer...
04:02	meltingwax	thank you, i will try that
04:03	opqdonut	:D
04:03	ejackson	meltingwax: some claim it to be a pattern.
04:04	opqdonut	541052.14 meltingwax$ thank you, i will try that
04:04	opqdonut	oops
04:14	rata_	good night
04:14	rata_	see you
05:16	fliebel	morning
05:23	no_mind	is there a working example of compojure and enlive ?
05:30	bobo	i think most examples with enlive are with moustache instead of compojure :-/
05:31	Dranik	bobo, are there any?
05:33	bobo	examples of enlive + compojure? i have never seen any. but shouldnt be any problem reading about enlive with moustache and then change to compojure
05:33	no_mind	I think I have found the title for my next book... "Clojure for humans"
05:34	no_mind	bobo: they are not working with compojure...
05:34	no_mind	btw suggestion for any other templating engine to be used with compojure ?
05:34	no_mind	preferably something that can read files from hdd
05:35	bobo	no_mind: in what way are they not working? point me to some example you are reading and il see if i can compojurise it
05:35	no_mind	bobo: take any example
05:35	no_mind	I am getting Null pointer exception
05:36	bobo	is your template working without compojure? if you just call it?
05:36	bobo	null pointers with enlive usualy mean you point to a non existing .html
05:37	no_mind	the .html is accesible from the route
05:38	bobo	yes, but does enlive find it? thats not the same thing
05:38	bobo	enlive looks from your src folder
05:38	no_mind	k
05:38	clojurebot	package.el is part of Emacs now: http://repo.or.cz/w/emacs.git/blob_plain/HEAD:/lisp/emacs-lisp/package.el
05:41	Dranik	bobo, how about mustache + enlive? are there any examples or tutorials?
05:42	bobo	https://github.com/swannodette/enlive-tutorial/
05:42	bobo	http://cleancode.se/2011/01/04/getting-started-with-moustache-and-enlive.html
05:42	bobo	the first is probably the better one, since i wrote the second :-p
05:43	raek	no_mind: it does not matter whether you use enlive with compojure or moustache.
05:43	Dranik	thanks
05:44	raek	I usually put my html templates in resources/ rather than src/, since they're not code
05:45	FkCek\|a	http://www.bestinclass.dk/index.clj/2011/01/building-a-social-media-site.html
05:45	Dranik	bobo, the first is not available
05:47	bobo	Dranik: its not? im looking at it?
05:48	Dranik	wow!
05:48	Dranik	This webpage is not available
05:48	Dranik	that's what I've got
05:48	Dranik	oh its working now
05:49	bobo	no_mind: https://gist.github.com/820290
05:49	bobo	index.html is in my src folder there, but as raek said they should be in resources in the end.
05:50	no_mind	k
05:51	bobo	raek: whats the best way to point the template to the resources folder?
05:51	bobo	just wrap-file ?
05:52	raek	deftemplate looks for files on the classpath and both src/ and resources/ are on it
05:52	bobo	ah
05:52	bobo	you learn every day!
05:59	raek	it would be nice if wrap-file could look for static files on a subdirectory of the classpath too...
06:56	cwb	startups
07:16	TobiasRaeder	morning
07:19	gfrlog	good morning
07:20	gfrlog	,(let [good-+ (fn [& args] (apply + (shuffle args)))] (good+ 7 8 9))
07:20	clojurebot	java.lang.Exception: Unable to resolve symbol: good+ in this context
07:20	gfrlog	,(let [good+ (fn [& args] (apply + (shuffle args)))] (good+ 7 8 9))
07:20	clojurebot	24
07:22	TobiasRaeder	is there some kind of idiomatic wrapper for dates in clojure?
07:23	fliebel	TobiasRaeder: I encountered Yoda-time a few times. It's used in sexpbot for example.
07:23	TobiasRaeder	then ill check that out how its done there, thanks
07:24	fliebel	TobiasRaeder: Oh, sorry, it's clj-time, which uses Yoda
07:25	TobiasRaeder	@fliebel clj-time looks nice :)
07:26	bobo	think its called joda-time with a j
07:54	no_mind	using enlive, how can I create a list element <li> dynamically from database? Given the template has a placeholder <ul. eleement.
07:55	fliebel	no_mind: I think you define one placeholder li, and repeat-for on a snippet of that li..
07:57	bobo	no_mind: https://gist.github.com/820462
08:09	no_mind	bobo: did you create a placeholder for <li> under <ul> in the template ?
08:10	bobo	no_mind: eh yes i belive so
08:10	no_mind	thnxs
08:10	bobo	https://gist.github.com/820477
08:10	bobo	i stole it from my post about it
08:13	jkdufair	i'm looking for advice
08:13	jkdufair	i'm building a RESTful app on top of compojure
08:14	jkdufair	i need a way to represent data across this web app and also an iPhone app and an AJAXy web app
08:14	jkdufair	use JSON or some representation of s-expressions?
08:16	bobo	i would use json
08:17	jkdufair	bobo: are you aware of any clojure libs that serialize to JSON?
08:17	bobo	clojure.contrib/json
08:18	bobo	or something, there is one in contrib
08:18	bobo	json-str and read-sjon
08:18	jkdufair	super. thanks so much.
08:28	Cozey	is it possible to do something like (let [field 'staticField] (. SomeClass field)) ?
08:28	clgv	How can I make clojure inline a very often called function? I saw snippets somewhere - is there any documentation on that?
08:29	jkdufair	Cozey: I would think you'd need to write a macro for that
08:30	fliebel	clgv: Sounds interesting. What does inlining do? I know some functions use :inline in the meta, but I doubt it's the same thing.
08:30	clgv	fliebel: I think that's what I saw too. But I didn't find documentation on it
08:31	fliebel	clgv: I did, somewhere on the assemba space I think.
08:31	raek	Cozey: at runtime, you need reflection for that
08:31	clgv	I have function that is called around 4,000,000 times in 10 iterations. so it would be a good candidate ;)
08:32	Cozey	jkdufair: but when I make a macro and pass a variable to it, say: field, and then unquote it with ~foo, i still get (. Class field), and not the value of field
08:32	jkdufair	Cozey: oh boy. that's when i usually start drinking to truly understand macro expansion
08:33	Cozey	i know you're right
08:33	Cozey	but i feel like i'm missing some 'deref' or something similar
08:33	raek	macros are just functions that transform code in form of data structures
08:34	fliebel	clgv: http://www.assembla.com/spaces/clojure/search?q=inline
08:34	raek	Cozey: . is a special form and cannot be "applied" at runtime. the compiler needs to know the name of the field when the code is complied
08:34	raek	*compiled
08:34	jkdufair	yes and rockets are just tubes with propellants that go up in the sky :-)
08:35	fliebel	clgv: So, no direct documentation, but a few issues mentioning the feature.
08:35	Cozey	so is it possible to get a field by name known during runtime, without resolving to eval ?
08:35	raek	Cozey: use clojure.lang.Reflector/getInstanceField if you need to do it at runtime https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/Reflector.java#L238
08:36	clgv	fliebel: guess I have to check clojure source to see where it is used
08:36	Cozey	raek: ok thanks, this seems to be what i needed!
08:36	fliebel	clgv: https://github.com/clojure/clojure/blob/b578c69d7480f621841ebcafdfa98e33fcb765f6/src/clj/clojure/core.clj#L809
08:37	clgv	fliebel: exactly the one I just clicked ;)
08:37	clgv	so well. it seems I have to repeat the definition in the inline statement
08:37	raek	Cozey: macros can be an alternative too (and would yield more performant code). it depends on how you are going to use it.
08:38	clgv	or define a macro for it ;)
08:38	fliebel	clgv: I think it's like definline for functions :)
08:39	Cozey	raek: yes but with macros i would need to know all the fields on compile time?
08:39	Cozey	without using Reflector
08:39	raek	(defmacro field-accessor [field-name] `(fn [instance#] (. instance# ~field-name)))
08:40	raek	Cozey: yes, but if the macro can figure out the field name at compile time (you have the whole clojure language at your disposal) then it would work
08:40	Cozey	agreed
08:42	clgv	fliebel: definline seems about right
08:42	AWizzArd	definline is the correct choice.
08:52	pdk	(doc definline)
08:52	clojurebot	"([name & decl]); Experimental - like defmacro, except defines a named function whose body is the expansion, calls to which may be expanded inline as if it were a macro. Cannot be used with variadic (&) args."
08:53	clgv	the syntax is a bit odd. seems you have to wrap the body into syntaxquotes
08:54	clgv	and use unquotes for the params everywhere
08:55	pdk	makes it just like macros already then!
08:56	clgv	I think it should be possible to do it without
08:58	fliebel	$source definline
08:58	sexpbot	definline is http://is.gd/bNmEu0
08:58	fliebel	It actually adds the thing to the meta data.
08:59	fliebel	clgv: This just works: (definline blah [foo] (println foo))
09:00	clgv	fliebel: my code with let-statement and more, does not ;)
09:00	fliebel	code?
09:00	clojurebot	peepcode is a commercial screencast series; see the Clojure one at http://peepcode.com/products/functional-programming-with-clojure by technomancy
09:01	clgv	I did wrap it into syntax quotes now.
09:03	clgv	I have to check both versions for a performance comparison now
09:04	chouser	definline essentially defines both a macro and a function with the same name
09:05	chouser	then Clojure chooses which to use at compile time based on how it's used.
09:06	fliebel	chouser: I guess that does not mean I can do macro tricks, and still use it as a function?
09:06	fliebel	And, in which cases is the macro used?
09:07	clgv	chouser: yes, that's what I saw. The question is: do I really need to use syntaxquotes? It didnt compile with out them
09:07	chouser	you can do (some) macro tricks, but they may only do what you mean in the macro version
09:09	clgv	I don't need macro tricks - inlining is sufficient^^
09:09	fliebel	clgv: Can you paste an example of why you need syntax quotes?
09:10	fliebel	Ah, I see...
09:11	clgv	clgv: no minimal that you can run since there are a lot of dependencies. just try to use a let and an if-statement with several comparisons and additions.
09:11	fliebel	clojure.lang.Symbol cannot be cast to java.lang.Number
09:12	chouser	the macro version is used when the var is named literally at the head of a list
09:12	chouser	so (foo ...) uses the macro, (map foo ...) and ((identity foo) ...) use the fn
09:12	clgv	hmm performance benchmark show no significant improvement. seems the function call is no overhead for this case
09:13	chouser	clgv: the HotSpot JVM will inline function calls at runtime
09:13	clgv	I had about 230000 calls
09:13	clgv	chouser: it seems to do a pretty good job here.
09:14	fliebel	chouser: So what is a good use case for definline?
09:14	chouser	the reason definline exists is to allow for unboxed primitives. Of course there's new support for those in 1.3a4
09:15	fliebel	So, definline is useless as of 1.3?
09:15	clojurebot	I don't understand.
09:15	chouser	I wouldn't be shocked if Rich removes :inline, but I would miss it. It's fun to exploit.
09:15	clgv	lol poor bot ;)
09:16	fliebel	chouser: Exploit? You mean makinf the fn do something unexpected when inlined?
09:16	chouser	yeah.
09:18	chouser	(definline add [a b] (if (and (number? a) (number? b)) (+ a b) `(+ ~a ~b)))
09:19	chouser	can you see what that does?
09:20	AWizzArd	This is evil!
09:20	clgv	good question. first case adds the numbers second case returns code that is an add statement
09:21	AWizzArd	First case is doing the addition at macro expansion time.
09:21	clgv	second-case is only used in macroexpansion time
09:21	chouser	everyone's right!
09:21	Chousuke	that's evil.
09:21	chouser	yes, evil.
09:21	AWizzArd	The second case calls a function + which is probably defined for a specific NS, where cores + is excluded.
09:21	chouser	well, useless at least
09:22	chouser	AWizzArd: nah, that's fine as clojure.core/+
09:22	Chousuke	but hm
09:23	Chousuke	how does it work when you call it as a function?
09:23	AWizzArd	Chousuke: second case.
09:23	chouser	definline uses the macro with symbol arguments it provides itself in order to create the function version
09:24	AWizzArd	It is just a hack for something that the compiler potentially could do: replace literals.
09:24	chouser	It is the compiler! :-D
09:24	clgv	on repl it seems to have a "good" behavior
09:24	fliebel	chouser: I can't get it to work wrong.
09:25	chouser	yeah, it may not be evil. Closer to useless.
09:25	fliebel	makeing one of them * would be evil :)
09:25	chouser	so (add 1 2) does the addition at macroexpand time, putting 3 literally in the resulting code
09:26	chouser	(let [a 1] (add a 2)) still calls the macro version, but sees that a isn't a number and puts (+ a 2) in the code
09:27	chouser	with (map add [1 2] [3 4]), the compiler sees it can't call add as a macro and uses the function version, which of course is essentially (fn add [a b] (+ a b))
09:28	AWizzArd	And Clojures + can not be optimized in such a way that (+ 1 2) is replaced by a literal 3.
09:29	chouser	I have used similar techniques to examine at compile time var values, do Java reflection, and generate substantially faster code, but fall back on perfectly acceptable runtime reflection when used as a function.
09:29	chouser	AWizzArd: why is that?
09:30	chouser	though I now think that's probably too much magic, despite how much fun it was. It's probably better to provide separate macro and function and let the user choose in such cases.
09:31	AWizzArd	Clojure can not know what + means until the program runs, because there is no defconstant.
09:31	AWizzArd	(def + -)
09:31	AWizzArd	(+ 10 2)
09:31	clojurebot	suffusion of yellow
09:31	AWizzArd	,(let [+ -] (+ 10 2))
09:31	clojurebot	8
09:31	AWizzArd	Dynamically typed.
09:32	chouser	the compiler can tell the difference there
09:32	chouser	and in fact does so.
09:32	AWizzArd	What about (in-ns 'clojure.core) (def + -) (in-ns 'my.ns)
09:33	AWizzArd	Functions can be changed at runtime in Clojure.
09:33	AWizzArd	This means that during compile time it is not known what a call will actually do.
09:33	chouser	Clojure assumes vars don't change from being macros to functions or vice-versa at runtime.
09:34	AWizzArd	Yes okay, macros will stay macros, fns will stay fns. However, the value of the var may change.
09:35	AWizzArd	I can do a (defn foo [] 1) and then after this (defn foo [] 2)
09:35	AWizzArd	I can eval things at runtime that changes the code. So during compile time we can not optimize such things away without using your definline trick, which is able to do it.
09:37	chouser	Clojure could inline such things if it also inlined a check to make sure the value of the var hasn't changed.
09:38	AWizzArd	(foo x) could mean anything at runtime.
09:38	AWizzArd	Its meaning could change constantly.
09:38	chouser	no, foo must be either a var or a local
09:39	AWizzArd	Vars can be def'ed.
09:39	chouser	if it's a var, it's known at compile time to be a specific var in a specific namespace
09:39	AWizzArd	Yes, but it's value is not known.
09:40	chouser	usually it's value is known at compile time, and usually it won't change.
09:40	chouser	so Clojure could inline the current value, preceeding that inlined code with a check to make sure the var's value hasn't changed.
09:40	chouser	if it has, it would have to call out to a slower path instead of using the inlined version.
09:40	AWizzArd	usually yes, in nearly all cases
09:40	fdaoud	its value
09:41	AWizzArd	But it is not known 100%.
09:41	AWizzArd	In a loop foo could change constantly (if (= user-input 10) (defn foo [] 1) (defn foo [] 2))
09:41	chouser	in practice, Clojure doesn't have to do this because HotSpot already does.
09:41	AWizzArd	Yes, HotSpot can do it at runtime.
09:42	AWizzArd	With more (static) information during compiletime however it could be done by the compiler.
09:42	chouser	I just exaplained how it could be done at compile time by the compiler.
09:42	AWizzArd	For example I sometimes wished there was a defconstan.
09:43	AWizzArd	Yes, the compiler can add an if.
09:43	AWizzArd	If it were known at compile time that a function could never change then this if would not be required too.
09:43	chouser	this gives you the benefit of inline performance in the most common cases without giving up the features of dynamic redefinition when you really need it.
09:44	chouser	even if you didn't know you were going to need it when you wrote that code
09:44	AWizzArd	Yes.
09:45	chouser	Clojure 1.3 now reduces the overhead required in that 'if' even more, and is part of the general speed improvement people are seeing there.
09:45	AWizzArd	My point is that your definline can do an optimization during macro expansion time which can not be done as long we want a dynamic system.
09:46	AWizzArd	How does it reduce an overhead in 'if'?
09:48	mtopolnik	i'm having a hard time with lazy-xml
09:49	mtopolnik	as soon as i access an element, it eagerly parses its whole contents
09:49	chouser	the details grow fuzzy in my head. I think it has something to do with in 1.2 each var had it's own volatile while in 1.3 all non-dynamic vars share a single global "var version" counter
09:50	mtopolnik	e.g. <root><first/><second><a/><a/><a/>......</second></root>
09:50	mtopolnik	as soon as i reach second, it parses all the a's
09:50	mtopolnik	even if i just ask for the :tag of second
09:51	mtopolnik	i've tried with xml-zip as well, but same problems
09:54	mtopolnik	is this behavior expected?
09:56	AWizzArd	chouser: I see.
10:45	fliebel	$seen dnolen
10:45	sexpbot	dnolen was last seen quitting 18 hours ago.
10:59	mattmitchell	i'm attempting to build up a string, conditionally. this is harder than i thought due to immutable state. the only thing i can think of is to use nested "let"s.
10:59	mattmitchell	does that seem like an ok solution?
11:01	fliebel	mattmitchell: A let binding can refer to previous bindings. ##(let [a 1 b (+ 1 a)] b)
11:01	sexpbot	⟹ 2
11:01	cemerick	mattmitchell: probably, but others may be better. e.g. str ignores nil arguments, so…
11:01	cemerick	&(apply str ["foo" (when false "bar") "baz"])
11:01	sexpbot	⟹ "foobaz"
11:02	mattmitchell	interesting
11:02	pdk	if you're building it up iteratively see if you can translate that into some recursive form with each call adding another piece to the return value
11:02	fliebel	You should also look at -> ##(-> "foo" (str "bar") (str "baz"))
11:02	sexpbot	⟹ "foobarbaz"
11:02	raek	I guess one way could be to let each part of the string to be constructed to, either to some string value if it's going to be included, or to the empty string if it's not, and then just concatenate all the parts
11:02	pdk	or if you really think it'll be best to just do it iteratively stick the string value inside an atom which you can handle mutably
11:03	mattmitchell	wow thanks. good stuff.
11:03	cemerick	pdk: I can't say I've ever seen a scenario where that would make sense.
11:06	raek	(let [h (if-not (zero? hours) (format "%02d:" hours) ""), m (if-not (or (zero? hours) (zero? minutes)) (format "%02d:" minutes) ""), s (format ":%02d" seconds)] (str h m s))
11:22	mattmitchell	raek: thanks. nice example.
11:25	mattmitchell	,(contains? [1 2] 1)
11:25	clojurebot	true
11:25	fliebel	Has anyone here worked with Logos? I mean, you know, did some actual stuff with it.
11:25	mattmitchell	,(contains? [1] 1)
11:25	clojurebot	false
11:25	mattmitchell	... what's up with (contains? [1] 1) being false?
11:25	fliebel	mattmitchell: Common pitfall, contains? checks for index.
11:25	mattmitchell	fliebel: ah :)
11:26	fliebel	Try ##(some #{1} [3 4 5 1])
11:26	sexpbot	⟹ 1
11:26	mattmitchell	,(some [1] [1])
11:26	clojurebot	java.lang.IndexOutOfBoundsException
11:27	fliebel	with a set, not a vector.
11:28	mattmitchell	,(set [12])
11:28	clojurebot	#{12}
11:28	mattmitchell	,(some (set [1]) 1)
11:28	clojurebot	java.lang.IllegalArgumentException: Don't know how to create ISeq from: java.lang.Integer
11:28	fdaoud	,(contains? [4 5] 1)
11:28	clojurebot	true
11:28	fdaoud	goof
11:28	mattmitchell	,(some (set [1]) [1])
11:28	clojurebot	1
11:29	chouser	,(#{4 5} 1)
11:29	clojurebot	nil
11:29	chouser	,(#{4 5} 5)
11:29	clojurebot	5
11:30	sritchie	pandora
11:30	sritchie	whoops, sorry, quicksilver kind of abandoned me there
11:30	fliebel	Are there javadocs for clojure.core? I'd be interested in the "known subclasses", so I can tell everything in Clojure that implements IFn.
11:48	Vinzent	Is it correct that (symbol "") returns something?
11:49	Vinzent	and not throws exception
11:50	raek	&(some (fn [x] (if (even? x) [:found-it x] nil))) [1 3 5 6 7])
11:50	sexpbot	java.lang.IllegalArgumentException: Wrong number of args (1) passed to: core$some
11:50	raek	&(some (fn [x] (if (even? x) [:found-it x] nil)) [1 3 5 6 7])
11:50	sexpbot	⟹ [:found-it 6]
11:50	raek	&(symbol "")
11:50	sexpbot	⟹
11:51	raek	&(class (symbol ""))
11:51	sexpbot	⟹ clojure.lang.Symbol
11:51	raek	Vinzent: seems like it returns a symbol, whose name is the empty string...
11:51	Fossi	nifty
11:51	Fossi	&(symbol "a")
11:51	sexpbot	⟹ a
11:52	fliebel	&@clojure.java.javadoc/local-javadocs
11:52	sexpbot	java.lang.ClassNotFoundException: clojure.java.javadoc
11:53	raek	&(require 'clojure.java.javadoc)
11:53	sexpbot	java.security.AccessControlException: access denied (java.util.PropertyPermission os.name read)
12:03	fliebel	All classes implementing IFn: AFn, AFunction, AMapEntry, APersistentMap, APersistentSet, APersistentVector, ATransientSet, Keyword, LispReader.CharacterReader, LispReader.CommentReader, LispReader.DeprecatedWrappingReader, LispReader.DiscardReader, LispReader.DispatchReader, LispReader.EvalReader, LispReader.FnReader, LispReader.ListReader, LispReader.MapReader, LispReader.MetaReader, LispReader.RegexReader, LispReader.SetReader, LispReader.Strin
12:05	fliebel	What does a MapEntry do when called?
12:06	dnolen	wow, Google 'thread-local binding' and the first thing that comes up is Clojure. Neat idea that also seems to have origin in Mozart/Oz, seems like you could easily build Computation Spaces as described in CTM as a result.
12:07	chouser	whoa, the readers are IFns? I had never noticed.
12:07	fliebel	Hey dnolen! The Reasoned Schemer arrived yesterday. Could you shine some light on the differences between that and Logos?
12:08	dnolen	fliebel: logos.minikanren is a faithful implementation of the original ideas with considerable changes to get better performance, as well a solution to the fact that Clojure does support pairs.
12:08	dnolen	Clojure doesn't support pairs I mean.
12:09	fliebel	dnolen: what pairs?
12:09	dnolen	fliebel: (a . b) where b is not a proper tail is allowed in Scheme/Common-Lisp, not allowed in Clojure
12:09	fliebel	I also noticed that fresh seems to be replaced by exist?
12:14	chouser	(1 . 2) is what is returned by (cons 1 2)
12:14	fliebel	ah
12:14	chouser	I've always found the syntax to be confusing
12:15	chouser	(1 2 3 4) is the same as (1 . (2 . (3 . (4 . nil)))) I believe
12:15	fliebel	dnolen: And what is this solution?
12:15	fliebel	chouser: In Scheme, or in Clojure as well?
12:15	chouser	Clojure doesn't support dotted pairs. the "rest" of a seq is always a seq or nil, never a number or anything else.
12:16	chouser	,(cons 1 2)
12:16	clojurebot	java.lang.IllegalArgumentException: Don't know how to create ISeq from: java.lang.Integer
12:16	fliebel	&(cons 1 (cons 2 nil))
12:16	sexpbot	⟹ (1 2)
12:17	chouser	right. well-behaved lists, not dotted pairs of arbitrary values.
12:17	fliebel	I still don't understand the dots, then we could just as well start writing (1 + 1)
12:17	dnolen	fliebel: oh yeah, my version is based on the version in William Byrd's thesis (2009). The Reasoned Schemer is based on a earlier version (2005)
12:18	chouser	in general I think where you would use pairs in other lists, you use vectors in Clojure.
12:18	dnolen	fliebel: main differences, is fresh -> exist and they committed to interleaving search and abandoned Prolog depth-first option
12:18	chouser	fliebel: yes, the syntax is confusing. Maybe it helps to think of ( . ) as the whole thing. The parens there don't really mean the same as they do in a regular list.
12:19	chouser	would be less confusing if pairs were written as <1 2> or something. So <1 <2 <3 nil>>> is (1 2 3)
12:20	fliebel	dnolen: Is the later an implementation detail, or something I'm going to need to worry about?
12:20	dnolen	fliebel: the solution was to come up with with a new datastructure called LConSeq. This supports the tail being something other than a proper seq - in particular an un-ground logic variable.
12:20	fliebel	chouser: Yea.
12:20	dnolen	LConsSeq I mean.
12:21	chouser	dnolen: record or type?
12:21	pdk	i thought clojure forced all lists to be proper lists
12:21	dnolen	fliebel: Prolog depth-first has issues. interleaving search prevents certain forms of divergence that exist in Prolog.
12:21	chouser	pdk: it does. Sorry to confuse, I'm talking about other lisps here.
12:21	dnolen	chouser: type. record adds a bunch of Seq stuff I don't want.
12:24	fliebel	dnolen: Thanks :) I only just did the first chapter of The Reasoned Schemer, and I'm really enjoying it. I'm trying to use Logos to try things out.
12:24	fdaoud	,(let [a + + 2] (a + 4))
12:24	clojurebot	6
12:24	dnolen	fliebel: cool, careful there's one major bug I haven't had time to tackle not sure if it'll crop up w/ their examples.
12:26	fliebel	dnolen: What is it? Surely not the set/map unification mentioned in the issue on github.
12:27	dnolen	fliebel: no, set/map unification works now. sets are a bit slow tho. issue is a bit hard to explain, but it has to do with cond-e.
12:29	fliebel	dnolen: I think you said something about a blog post about connecting the ends, any news on that? (I see what you meant with the book layout now :)
12:30	dnolen	fliebel: TRS is particularly sweet in that you come to understand the fundamental idea behind Prolog in about ~200 LOC. The hardest 200 LOC I've ever read :)
12:32	dnolen	fliebel: I'll need to find some time, but the book glosses over half of the implementation. Unification/substitution is a tough topic, they cover that. Then they completely skip over how they produce the stream of solutions. William Byrd's thesis covers that, but their implementation is dense.
12:34	dnolen	fliebel: I think my version is easier to follow, since Clojure has real type dispatch.
12:35	dmiles_afk	my dream intepretor is LISP+PROLOG+CLOJURE on a JVM
12:35	dmiles_afk	or even .NET
12:35	dmiles_afk	oh but making it very efficient :)
12:39	fliebel	dnolen: Cool, awesome work :) gtg now. I think I'll have loads of questions for you later, when I catch you here the next time :)
12:58	fliebel	What are RestFn and PersistentTreeMap?
12:58	phenom_	hey everyone, i was having a convo with a colleague and he points out that multimethods make explicit use of casting to dispatch and casting is wrong ... how do i respond ?
12:59	fliebel	phenom_: Casting?
13:00	amalloy	phenom_: i suggest telling him he is crazy
13:01	__name__	good morning
13:01	Scriptor	morning __name__
13:01	phenom_	amalloy: I need more than that :P I try to explain that we separate the decision process from the code acting on the parameters, which he responds with "well, just because they're separate, doesn't mean it's not effectively a huge if/else check"
13:02	raek	phenom_: like in java? if (x instanceof Foo) { Foo y = (Foo) x; ... }
13:02	chouser	where is casting being done? what's wrong with casting? what's wrong with a huge if/else check?
13:02	chouser	I'm clearly confused.
13:02	__name__	can you include a route as a subdirectory of a route in compojure? so, e. g., foo/* is matched as * in another route?
13:02	amalloy	phenom_: the difference is it's not centralized like an if/else
13:03	phenom_	but it still is just a large if/else check for any types i want to handle right ?
13:03	amalloy	if apache released a clojure library with a multimethod in it, i could add my own types of objects and have them handled flawlessly by the existing multi
13:03	amalloy	try doing that with a "real" if/else
13:03	dmiles_afk	if (x instanceof Foo) ((Foo)x).bar(); benches way faster than just ((Foo)x).bar(); btw
13:04	phenom_	so it's a sort of dynamic if/else
13:04	dmiles_afk	after JIT
13:04	phenom_	i can add as I like
13:04	raek	phenom_: I think that two of the points with multimethods are that their implementations is an open set (can be extended by others) and they don't have to be defined inside a type in order for it to be able to participate
13:05	amalloy	dmiles_afk: really? that's surprising
13:05	raek	also, the hierarchy used for selecting the method does not have to be the java class hierarchy
13:05	amalloy	even if x is always a Foo?
13:05	dmiles_afk	amalloy: CHECKCAST is removed in the ifelse
13:05	phenom_	but to participate, for most scenarios I'll need to do a cast
13:05	phenom_	(eg. vector? seq? etc)
13:06	raek	clojure is dynamically typed, so you don't cast more than usual
13:06	hiredman	that is not a cast
13:06	dmiles_afk	but what saddens me is that ((Foo)x).bar(); is faster than x.bar();
13:06	chouser	I'm so confused.
13:06	dmiles_afk	if "Foo" inherits the method
13:07	raek	phenom_: what do you mean by "cast"?
13:07	phenom_	eek, isn't a call to vector? a class check ?
13:07	dnolen	multifns use a dispatch table and they cache lookups. I don't know where if/else or casting comes into the picture.
13:07	dnolen	phenom_: ^
13:08	dmiles_afk	so hopfully in bytecode clojure if/else casts to the actual implmneting type
13:09	raek	for me, a (dynamic) cast is the operation of turning an Animal reference into a Cat reference when you know it is one
13:09	dmiles_afk	so hopfully in bytecode clojure if instanceofs and then casts to the actual implmneting type
13:10	raek	clojure does casts when doing java method invocations. clojure fns are Objects -> Object
13:10	dmiles_afk	thats good it does assume coercions
13:11	dmiles_afk	thats good it DoesNT assume coercions
13:11	phenom_	dnolen: i mean deciding which function to call is done with a class check (instanceof) ... get (vector?)
13:12	amalloy	phenom_: no
13:12	raek	phenom_: a multimethod has a dispatch function that yields a dispatch value when passed the arguments of the invocation. this function can be 'type'
13:12	dmiles_afk	i'd kinda hope that (vector? ..) means it implements a IClojureVector or somesuch
13:12	amalloy	pseudocode: (let [dispatch-fns {Vector vector-fn, List list-fn}] ((dispatch-fns (class arg)) arg))
13:13	chouser	phenom_: when a multimethod is called, your dispatch function is invoked first. It is not uncommon for the dispatch fn to get the class of the first arg, but it can do whatever you want.
13:13	dmiles_afk	as in instanecof IClojureVector
13:13	amalloy	but it doesn't have to be a class-based dispatch
13:13	raek	phenom_: then you define implementations for some dispatch values (e.g. String, Integer, Keyword, etc)
13:13	dmiles_afk	ah thats nice its not bound to java class structure
13:14	phenom_	right, so I am checking the class ... i understand you can dispatch on anything and return any value also
13:14	chouser	if you ask for the class of the object, that's what you get. Note this is not instanceof.
13:14	amalloy	somewhere around here i have a multimethod that dispatches on the size of its argument with (defmulti blah count)
13:15	chouser	after your dispatch fn returns something (such as a class), clojure does a (memoized) heirarchy lookup to find the appropriate defmethod to call.
13:15	phenom_	but even for functions like get .. internally it needs to check class type (PersistentVector or PersistentMap) to properly dispatch ?
13:15	amalloy	chouser: as a side note, i imagine it dumps out the whole memoization cache if you add a new dispatch fn
13:16	chouser	amalloy: I believe that's correct. or if you change the heirarchy. :-)
13:16	dmiles_afk	one day i am sure it could be surgicall dumped
13:16	phenom_	is there a detailed book that goes into the internals? or is it just a learn by reading code kinda thing ?
13:17	amalloy	phenom_: the internals are not very interesting. you are ascribing properties to them that they do not have
13:17	raek	the comparison would be more like x.getClass == c rathern than x instanceof C
13:17	chouser	phenom_: clojure.core/get is not a multimethod.
13:17	amalloy	in pseudo-java: switch (foo.getClass()) {case List: foo.length(); case Map: foo.size();}
13:18	amalloy	and because you can add new case statements at any time, it's a million times less brittle than an if/else or actual switch
13:18	chouser	phenom_: clojure.core/get currently has an if/else inside to do the right thing. It may later be done with a protocol, which would amount to much the same thing.
13:19	amalloy	chouser: really? i would have expected that it casts to IAssociative and calls the interface method or something
13:19	phenom_	chouser: RT.get does instance checks no ?
13:19	phenom_	*class check
13:20	dnolen	phenom_: getting a class and an isa? check is like the fastest thing possible on the JVM. you can do that a billion times in less than a second. also you can us a class as a map key, if you don't find it, then you do the isa? check on all keys, once you find it, you cache it.
13:20	chouser	amalloy: it does, but besides supporting ILookup and IPersistentSet, get supports java.util.Map, strings and arrays.
13:20	dnolen	,{(class []) :look-ma-a-class-as-a-key}
13:20	clojurebot	{clojure.lang.PersistentVector :look-ma-a-class-as-a-key}
13:20	amalloy	chouser: yeah, i'm reading it now
13:21	chouser	amalloy: note the splitting of the 'get' method into 'getFrom'? I think that's to support better inlining by hotspot and/or branch prediction in the CPU.
13:23	amalloy	chouser: hm, i wonder why IPersistentSet doesn't extend ILookup
13:23	chouser	It may just be historical. I think ILookup is newer.
13:24	chouser	I need to write a ticket to extract Sequential from ISeq
13:32	mattmitchell	(doc select-keys)
13:32	clojurebot	"([map keyseq]); Returns a map containing only those entries in map whose key is in keys"
13:32	mattmitchell	,(select-keys {:one 1 :two 2 :three 3} [:two :one])
13:32	clojurebot	{:one 1, :two 2}
13:33	mattmitchell	hmm, is there a way to specify the keys you want, in order?
13:33	mattmitchell	oh oops... what i mean is, is there a way to specify the values you want, in order?
13:33	chouser	,(map {:one 1 :two 2 :three 3} [:two :one])
13:33	clojurebot	(2 1)
13:33	mattmitchell	chouser: awesome thanks
13:34	amalloy	chouser, mattmitchell: also ##((juxt :two :one) {:one 1 :two 2 :three 3})
13:34	sexpbot	⟹ [2 1]
13:34	mattmitchell	,(doc juxt)
13:34	clojurebot	"([f] [f g] [f g h] [f g h & fs]); Alpha - name subject to change. Takes a set of functions and returns a fn that is the juxtaposition of those fns. The returned fn takes a variable number of args, a...
13:35	mattmitchell	cool
13:35	amalloy	&(doc juxt)
13:35	sexpbot	⟹ "([f] [f g] [f g h] [f g h & fs]); Alpha - name subject to change. Takes a set of functions and returns a fn that is the juxtaposition of those fns. The returned fn takes a variable number of args, and returns a vector containing the result of applying each fn to the... http://gist.github.com/821050
13:35	mattmitchell	,(prn "test")
13:35	clojurebot	"test"
13:35	mattmitchell	&(prn "test")
13:35	sexpbot	⟹ "test" nil
14:10	markskilbeck	Hi, all. Say I have a vector of 10 elements, and I want to change 2 random elements of it. How would I go about writing a function to do that?
14:10	markskilbeck	dotimes?
14:12	amalloy	markskilbeck: do you actually want to change them in place, or return a modified copy?
14:12	amalloy	(if the former, reconsider because that is evil)
14:12	markskilbeck	A modified copy, I suppose.
14:12	rata_	hi
14:12	markskilbeck	As is the way of clojure.
14:12	markskilbeck	Sup, rata_.
14:12	amalloy	in that case, you don't want anything that starts with "do" - those usually just perform side effects
14:13	markskilbeck	Noted.
14:14	amalloy	markskilbeck: you probably want to select two indices at random, then perform the swaps. you might be interested in the discussion fliebel and i had a week or two ago about shuffling
14:14	dnolen	,(-> [1 2 3 4] (assoc (rand-int 4) 'foo) (assoc (rand-int 4) 'bar))
14:14	clojurebot	[1 bar foo 4]
14:14	dnolen	no so thing as changing a vector in place anyway
14:14	dnolen	s/so/such
14:14	sexpbot	<dnolen> no such thing as changing a vector in place anyway
14:14	clojurebot	Gabh mo leithscéal?
14:15	markskilbeck	dnolen: That's fine, though if I then want to modify 3 indices, I've got to duplicate code.
14:15	amalloy	markskilbeck: iterate
14:15	markskilbeck	Ah!
14:15	markskilbeck	Bob's your mother's brother.
14:16	amalloy	&(nth (iterate #(assoc % (rand-int (count %)) 'foo) [1 2 3 4 5 6] 3)
14:16	sexpbot	java.lang.Exception: EOF while reading
14:16	amalloy	&(nth (iterate #(assoc % (rand-int (count %)) 'foo) [1 2 3 4 5 6]) 3)
14:16	sexpbot	⟹ [foo 2 foo 4 5 foo]
14:16	amalloy	but this might result in hitting up the same index multiple times, resulting in fewer than N elements changing
14:17	markskilbeck	That's fine.
14:21	markskilbeck	So the (nth ... 3) takes the third? iteration?
14:22	amalloy	markskilbeck: it takes the fourth entry in the list, where the zeroth entry is the original vector
14:23	amalloy	https://gist.github.com/805747 is several different approaches to a very similar problem that you might be interested in
14:23	amalloy	and http://www.raynes.me/logs/irc.freenode.net/clojure/2011-02-01.txt contains a discussion of the above
14:24	markskilbeck	Brill. Thanks.
14:25	markskilbeck	Wait, why the 4th entry? I wanted to modify only 2 indices, but wouldn't that modify (possibly) 4?
14:25	amalloy	markskilbeck: it will modify up to three
14:26	amalloy	0th entry modifies 0, 1st entry 1, 2nd entry up to 2...
14:26	amalloy	i think my original statement was poorly worded
14:26	markskilbeck	I see, I see.
14:27	amalloy	&(take 5 (iterate #(conj % 10) []))
14:27	sexpbot	⟹ ([] [10] [10 10] [10 10 10] [10 10 10 10])
14:27	markskilbeck	amalloy: you're most helpful
14:28	amalloy	markskilbeck: you're welcome!
14:31	markskilbeck	And that is a _long_ discussion.
14:32	amalloy	markskilbeck: well it's an interesting topic :)
15:13	rata_	LauJensen: I'm reading your post http://www.bestinclass.dk/index.clj/2009/10/brians-brain-echoes-from-the-web.html and don't understand why the 1d vector for the board representation is not accurate
15:13	LauJensen	rata_: Because there is no way to tell from a single index where exactly on the board you are, ie. left isn't simply -1 as it might move you up one row. It creates pretty patterns but its not Brians Brain anymore
15:18	rata_	LauJensen: oh ok =)
15:21	rata_	LauJensen: but the important thing was that using a 1d vector instead of a matrix made the performance improvement, so it's maybe worth fixing the neighbours fn
15:21	LauJensen	rata_: See Christophes follow-up posts for major performance boosts
15:21	LauJensen	He made it even faster than the CL version
15:21	rata_	using clojure?
15:23	rata_	LauJensen: where can I find Christophes follow-up posts?
15:23	rata_	LauJensen: did he use clojure?
15:24	LauJensen	http://clj-me.cgrand.net/page/2/
15:26	rata_	thanks
16:10	rata_	LauJensen: do you know if it's possible to make the rendering and the computation run at 25fps? I don't want to miss frames
16:10	rata_	interesting optimizations has done cgrand to your code btw
16:19	amalloy	markskilbeck: out of curiosity what method did you end up using?
16:40	edoloughlin	Is there any hope of attaching clojure source to a referenced JAR file in Counterclockwise (e.g., clj-record)?
16:54	cinch	Moooooo
17:00	_2x2l	do the TheDeadline guys hang out around here?
17:06	cinch	(whois _2x2l)
17:19	TimMc	I've been using the warn-on-reflection flag, and was surprised to see that @dereferences do not carry their :tag metadata through.
17:21	amalloy	TimMc: @foo is sugar for (deref foo). how would you type-hint the deref function to make that work?
17:21	TimMc	Good question.
17:22	TimMc	I guess I'm still kind of fuzzy on how type hinting works.
17:23	amalloy	TimMc: it would require type-inference that clojure doesn't really have (yet?)
17:25	TimMc	So (. obj method arg) will not need reflection if arg is :tagged explicitly, and (. obj method (producer)) works similarly... but @arg is hiding a function call.
17:26	TimMc	I suppose you'd have to have some mechanism to say "my type is the same as parameter 3's type" or somesuch. :-/
17:28	amalloy	TimMc: indeed, and java's generics do that
17:29	amalloy	public <T> T deref(IDeref<T> obj) {return obj.deref();}
17:31	TimMc	Oof, I really shouldn't be :tagging those (ref)s anyway -- it's their contents that I want to hint.
17:33	dnolen	TimMc: question is, what are you putting in refs that need type-hinting ?
17:33	TimMc	AffineTransform instances.
17:34	dnolen	TimMc: for what benefit?
17:34	TimMc	My graphics app needs to update those as the viewport changes.
17:35	TimMc	I don't want my coordinate transforms to get out of sync with the rotation, scaling, etc.
17:35	TimMc	I suppose that as long as they are only modified from the event loop I don't really need the transactions...
18:01	mattmitchell	how can i check if a string starts with a regexp?
18:02	amalloy	&(doc re-find)
18:02	sexpbot	⟹ "([m] [re s]); Returns the next regex match, if any, of string to pattern, using java.util.regex.Matcher.find(). Uses re-groups to return the groups."
18:02	brehaut	use an start anchor in the regexp
18:02	amalloy	&(map #(re-find #"^blah" %) ["blahtwer" "wablah"])
18:02	sexpbot	⟹ ("blah" nil)
18:10	tomoj	xb
18:58	TimMc	I'm implementing an undo/redo buffer for my program. I think I should move my def'd userdat variables into a map, and then I can push the current map onto the undo buffer before I change data in response to the user.
18:59	TimMc	So, question: Is there a way to keep the :doc metadata?
18:59	TimMc	(on the individual wads of state that I keep for the user)
19:00	brehaut	,(meta ^{:doc "foo"} {:a 1})
19:00	clojurebot	{:doc "foo"}
19:00	tomoj	are you sure you want vars there?
19:00	TimMc	brehaut: I want doc on :a. :-/
19:01	TimMc	Am I asking for something that doesn't exist?
19:02	tomoj	yes, keywords can't have metadata
19:02	brehaut	TimMc: if you want it on a keyword then yes
19:02	TimMc	That is, by consolidating a bunch of (def ^{:doc "stuff"} foo ()) into (def userdata {:foo ()}), I lose individual docstrings?
19:03	brehaut	,^{:doc "foo"} :a
19:03	brehaut	for instance
19:03	clojurebot	Metadata can only be applied to IMetas
19:03	TimMc	Hmm, OK.
19:03	tomoj	are users of your program familiar with clojure?
19:03	brehaut	is clojurebot going to throw me the exception?
19:03	tomoj	that's the only way it makes sense to me for that stuff to be in vars
19:03	TimMc	tomoj: This is internal stuff.
19:04	tomoj	better question: does your program include a clojure repl?
19:04	TimMc	tomoj: What is the alternative? (This is an interactive graphics program using Swing, to give some context.)
19:05	tomoj	so how do you change the data in response to the user?
19:05	TimMc	I have components that have event listeners that call functions (to update state) that need to refer to the components.
19:05	tomoj	what I mean is, how do you update the state
19:06	tomoj	def, again? alter-var-root? what?
19:06	TimMc	def
19:06	TimMc	(again)
19:06	tomoj	ok, pretty sure what you're doing is evil then
19:06	TimMc	Hah, OK.
19:06	tomoj	maybe an atom would be better suited?
19:07	tomoj	hard to say since I still don't really get what you're doing. but vars aren't variables, and if you're treating them like the variables you're used to, it's probably bad
19:08	TimMc	I've done some functional programming in the past, but I've never had to deal with this much mutable state in that context before.
19:08	tomoj	the only reason you're even allowed to redef is for development
19:08	TimMc	OK, I will definitely keep that in mind!
19:08	brehaut	im also wondering if you are abusing the metadata stuff?
19:09	tomoj	the other state abstractions to look into are atoms, refs, and agents
19:09	brehaut	metadata is largely for tooling (or so i understand)
19:10	TimMc	brehaut: I doubt it. I just like using machine-discoverable doc syntax.
19:10	TimMc	If I ever use a smart IDE to work on my code, this should make it easier to work with.
19:11	TimMc	tomoj: I tried refs, but I think they're more high-powered than I need. Agents look scary and alien, but I will learn what to use them for at some point.
19:12	tomoj	with (def userdata (atom {:foo ()}))
19:12	brehaut	TimMc: refs are always a good safe bet
19:13	tomoj	you can do things like (swap! userdata update-in [:foo] conj 3)
19:13	tomoj	then (:foo @userdata) is (3)
19:13	brehaut	they have additonal coordination semantics so if you ever need to access two refs, they can be transactional
19:14	TimMc	STM, yeah
19:14	brehaut	however, if you just have a undo stack, current doc, redo stack structure (perfect case for a zipper) then all you'd need is an atom
19:15	TimMc	zipper... heard of, but never used one of those before! Exciting.
19:15	brehaut	TimMc: basically its a double linked singlely ended list
19:16	TimMc	Aren't they more like tree+cursor?
19:16	brehaut	descibed as a pair of singly linked list
19:16	brehaut	completely persistent
19:16	brehaut	i think there may be a couple of things with the same name
19:17	brehaut	or the tree version is a generalisation of the list version
19:18	TimMc	hmm
19:18	brehaut	i am trying to look it up to find some docs for you, but my internet is running slow as mollasas
19:20	TimMc	brehaut: Thanks, but I don't know if I need a dedicated data structure for this -- a couple of functions oughta take care of this.
19:24	brehaut	TimMc: im not sure i understand; an undo / redo stack and current state in a world with persistent data structures is exactly this thing
19:25	TimMc	Sure, but I can just use two lists and conj/rest.
19:25	TimMc	I'd effectively implement the same thing myself.
19:26	brehaut	yeah thats the bit i dont understand
19:26	TimMc	Well, I don't know the name of the thing I'd want to use instead, or if Clojure has it.
19:29	TimMc	If I find out, I'll happily switch to using it. :-)
19:30	TimMc	(Since I am very much still learning Clojure, I don't consider it a waste of time to try to reimplement things that I could just grab libraries for.)
19:42	amalloy	brehaut: i had a good non-tooling use of metadata. maybe it was evil, i dunno
19:42	brehaut	amalloy: im sure they exist, but im sure its the minority
19:42	amalloy	brehaut: agreed. i think it's the first time i've had a reason
19:42	amalloy	for meta of any kind
19:48	amalloy	if anyone's interested, i wanted to wrap up "get this from the database" in a function so i could pass it to non-db-aware code; i attached meta to the function about what kinds of things it was looking for so i could use it to write to the database if i needed to
20:17	rata_	brehaut and amalloy: I use metadata for storing the connected components of a graph and not have to recompute them... don't know if that's considered evil
20:17	brehaut	rata_: my rule of thumb is 'is it actual data for my program'
20:19	brehaut	if its actual data, then i'd use a map or record
20:20	bytecolor	rata_: isn't that sort of how clojure.zip is implemented?
20:20	rata_	it's not any additional data... it's computable from just the data it goes with
20:21	rata_	bytecolor: I don't know... haven't looked at clojure.zip implementation
20:27	brehaut	bytecolor: zip attaches the functions used to create the zipper (eg branch? end? etc) but the actual path and context information is part of the zipper itself
20:28	bytecolor	ah, ok. I'd only peeked at the code a couple times.
20:28	amalloy	brehaut: "actual data" and "my program" seem almost too vague to be useful here
20:29	bytecolor	I think I've learned clojure mostly from reading the core and contrib source.
20:30	bytecolor	waiting on the dead tree version of the joy of clojure to come out
20:30	no_mind	Someone explain to me what exactly is this code snippet doing (map #(section-model % link-model) sections)
20:31	no_mind	wha tis % operator ? I cant find it even in cheatsheet
20:32	amalloy	no_mind: anonymous function shorthand
20:32	phenom_	how do i add classes or dirs to the class path when i launch cake's swank ?
20:32	amalloy	#(foo % 10) === (fn [x] (foo x 10))
20:33	no_mind	amalloy: is anonymous function shorthand #() ?
20:34	amalloy	er...yes, i guess? i don't understand the question
20:38	TimMc	no_mind: It's not an operator.
20:38	no_mind	k
20:39	TimMc	no_mind: #(... % ...) is equivalent to something like (fn [x] ... x ...)
20:39	no_mind	k
20:39	TimMc	It's the single argument to the anonymous function.
20:39	brehaut	no_mind: http://clojure.org/reader
20:39	brehaut	under macro characters, dispatch
20:41	TimMc	no_mind: Note that I forgot an important pair of parens in my expansion.
20:45	TimMc	brehaut: If you're at all curious, I finally pushed my in-progress graphics app to github: https://github.com/timmc/CS4300-HW3/blob/master/src/timmcHW3/core.clj
20:48	TimMc	(I should add a "n00b at work" warning in the readme.)
20:49	brehaut	TimMc: im not sure why you need a seperate ref for past and future
20:50	brehaut	(def history (ref [[], []])) would suffice
20:50	TimMc	True. What's the advantage?
20:50	brehaut	simplicity
20:51	TimMc	And I suppose some conceptual atomicity as well.
20:51	brehaut	yes
20:51	brehaut	i dont think you need 3 ref-sets; you should be able to get by with one
20:52	brehaut	ffirst on your history ref will give you the current state
20:53	TimMc	Yeah, I did debate on whether to have the current state as part of the undo history or not.
20:53	TimMc	I need to think about that some more.
20:53	brehaut	it makes the updating of the undo and redo stack trivial
20:53	brehaut	you dont have to sidestep through the current state
20:56	TimMc	I've also been considering whether I want a more complex undo/redo system.
20:56	brehaut	no, you want to get your program working first :P
20:56	TimMc	Notice how most word processors will undo chunks of typing at a time?
20:58	TimMc	True.
20:58	pdk	hey uh
20:58	pdk	which libraries are clojurebot/sexpbot using for irc interaction again
20:58	TimMc	I wasn't planning on doing fancy skiplist history quite yet.
21:00	TimMc	pdk: clojurebot appears to be using PircBot, a Java thingy.
21:01	TimMc	I bet both are open source on github.
21:02	TimMc	pdk: https://github.com/Raynes/sexpbot
21:09	pppaul	anyone home?
21:09	pppaul	i'm feeling really stupid with a simple clojure problem i have regarding maping over a dictionary
21:10	brehaut	pppaul: oh?
21:10	pppaul	(map identity (vals v))
21:10	pppaul	({:id 6822400, :name "Adam Tran"} {:id 43535, :name "Sdfsfsd"})
21:10	pppaul	solve360.name-fixer> (map #({:id (:id %), :name (:name %)}) (vals v))
21:10	pppaul	the last line gives an error
21:10	brehaut	pppaul: maps return MapEntries for seqs
21:10	brehaut	they look like pairs
21:11	pppaul	um
21:11	pppaul	how can i get a visual on that?
21:11	pppaul	or is there a better way to do what i want?
21:11	brehaut	,(map identity {:a 1 :b 2 :c 3})
21:11	clojurebot	([:a 1] [:b 2] [:c 3])
21:11	pppaul	which is transforming a map
21:12	mattdw	pppaul: also, #({..}) is going to try to call the map, I believe, not return it
21:12	pppaul	oh
21:12	brehaut	mattdw: correct
21:12	pppaul	ok
21:13	mattdw	turn it into an (fn [v] ...) if you just want the map returned
21:14	pppaul	thanks
21:14	gfrlog	,(seq {:a 1 :b 2 :c 3})
21:14	clojurebot	([:a 1] [:b 2] [:c 3])
21:14	pppaul	i want to transform the map into a new map
21:14	pppaul	what would be the best way to do this?
21:14	gfrlog	you want to map the map?
21:14	Kowboy	don't confuse the map the function and map the datatype
21:14	brehaut	(into {} (map f m))
21:14	pppaul	datamap to datamap
21:15	gfrlog	you want to change the keys, the values, or both?
21:15	pppaul	like XSLT
21:15	brehaut	f needs to take a pair and return a pair
21:15	pppaul	cool
21:15	Kowboy	the function map will return a sequence, not a data map
21:15	pppaul	a seq of datamaps is ok
21:16	brehaut	eg ##(into {} (map (fn [[k v] [(dec k) (inc v)]) {1 2 3 4 5 6}))
21:16	pppaul	that's what i'm starting with
21:16	gfrlog	,(into {} (map (fn [[k v] [(dec k) (inc v)]) {1 2 3 4 5 6}))
21:16	clojurebot	Unmatched delimiter: )
21:16	gfrlog	,(into {} (map (fn [[k v] [(dec k) (inc v)]) {1 2 3 4 5 6})
21:16	clojurebot	Unmatched delimiter: )
21:16	Kowboy	can you give us an example of a 1 entry map and what you want it transformed into?
21:16	gfrlog	,(into {} (map (fn [[k v] [(dec k) (inc v)]] {1 2 3 4 5 6}))
21:16	clojurebot	EOF while reading
21:16	pppaul	({:id :name :etc....},{}) -> ({:id :name},{})
21:16	gfrlog	,(into {} (map (fn [[k v] [(dec k) (inc v)]] {1 2 3 4 5 6})))
21:16	clojurebot	java.lang.RuntimeException: java.lang.Exception: Unsupported binding form: (dec k)
21:17	gfrlog	,(into {} (map (fn [[k v]] [(dec k) (inc v)]) {1 2 3 4 5 6})))
21:17	clojurebot	{0 3, 2 5, 4 7}
21:17	gfrlog	ah finally
21:17	pppaul	interesting
21:18	Kowboy	can the bot tell me the doc string of (into)?
21:18	gfrlog	,(doc into)
21:18	clojurebot	"([to from]); Returns a new coll consisting of to-coll with all of the items of from-coll conjoined."
21:18	gfrlog	clojurebot: thanks
21:18	clojurebot	thanks for your suggestion, but as usual it is irrelevant
21:19	gfrlog	I think (into) is kind of an ugly function for these purposes. But I don't think there's anything better at the moment
21:19	gfrlog	,(into #{1 2 3} [2 3 4])
21:19	clojurebot	#{1 2 3 4}
21:20	brehaut	gfrlog: you could use hash-map or array-map
21:20	gfrlog	(doc hash-map)
21:20	clojurebot	"([] [& keyvals]); keyval => key val Returns a new hash map with supplied mappings."
21:20	Kowboy	curious, what is the purpose of splitting a multi-entry map into a bunch of single-entry maps?
21:20	gfrlog	Kowboy: I have no idea, who suggested that?
21:20	Kowboy	why wouldn't you just use a sequence of tuples (2 element sequences)?
21:20	gfrlog	,(doc array-map)
21:20	clojurebot	"([] [& keyvals]); Constructs an array-map."
21:21	Kowboy	pppaul is trying to do that
21:21	pppaul	({:id :name :etc....},{}) -> ({:id :name},{})
21:21	pppaul	that is what i want
21:21	gfrlog	brehaut: we were talking about mapping a map -- is that what you were suggesting hash-map for?
21:21	pppaul	i'm braindead now, though
21:21	Kowboy	what's the difference between {:a 1} and [:a 1] if you aren't going to have multiple keys?
21:21	pppaul	i haven't worked with maps much
21:21	brehaut	gfrlog: as a replacement for into {}
21:22	gfrlog	Kowboy: I agree
21:22	pdk	(doc into)
21:22	clojurebot	"([to from]); Returns a new coll consisting of to-coll with all of the items of from-coll conjoined."
21:22	gfrlog	brehaut: so if I want {"jack" 12, "jill" 15} to be mapped to {:jack, 13, :jill, 16}
21:22	amalloy	&(map hash-map {1 2 3 4})
21:22	sexpbot	java.lang.IllegalArgumentException: No value supplied for key: [1 2]
21:22	amalloy	&(map (partial apply hash-map) {1 2 3 4})
21:22	sexpbot	⟹ ({1 2} {3 4})
21:22	gfrlog	how would hash-map make that easier?
21:23	amalloy	but i agree with the others, it's sorta silly to want this
21:24	gfrlog	,(into {} (fn [[k v]] [(keyword k) (inc v)]) {"jack" 12, "jill" 15})
21:24	brehaut	gfrlog: you said "I think (into) is kind of an ugly function for these purposes. But I don't think there's anything better at the moment"; i was suggesting the alternatives
21:24	clojurebot	java.lang.IllegalArgumentException: Wrong number of args (3) passed to: core$into
21:24	gfrlog	,(into {} (map (fn [[k v]] [(keyword k) (inc v)]) {"jack" 12, "jill" 15}))
21:24	clojurebot	{:jack 13, :jill 16}
21:24	pppaul	(map (fn [v] {:id (:id v) :name (:name v)} ) (vals v)) : my solution
21:24	gfrlog	brehaut: I guess I'm thinking that using hash-map would be more cumbersome
21:24	amalloy	gfrlog: (for) will be a lot cleaner than (map (fn))
21:24	pppaul	i don't know what it didn't work with #(%) format
21:24	brehaut	i think so to, hence my original use of into { }
21:24	gfrlog	,(doc for)
21:24	clojurebot	"([seq-exprs body-expr]); List comprehension. Takes a vector of one or more binding-form/collection-expr pairs, each followed by zero or more modifiers, and yields a lazy sequence of evaluations of e...
21:25	gfrlog	brehaut: oh, okay -- I thought you were suggesting hash-map as better than into {}
21:25	pppaul	how would i use for?
21:25	gfrlog	amalloy: I'm getting that feeling that I've been missing out on a whole function for a long time
21:25	zakwilson	I'm still not used to the pervasive destructuring in Clojure. I see people post examples like the above and I want to go refactor all my ugly code.
21:25	amalloy	&(into {} (for [[k v] {"jack" 11 "jill" 15}] {(keyword k) (inc v)}))
21:25	sexpbot	⟹ {:jack 12, :jill 16}
21:26	pppaul	wow, that is over my head
21:26	pppaul	"jack" -> :jack ???
21:26	gfrlog	pppaul: for isn't that bad
21:27	pppaul	i would really like a tutorial on for
21:27	brehaut	pppaul: ##(keyword "foo")
21:27	sexpbot	⟹ :foo
21:27	gfrlog	pppaul: are you wondering what the :jack syntax means?
21:27	pppaul	i'm wondering how "jack" is transformed into :jack
21:27	gfrlog	,(for [x (range 5)] [x (inc x)])
21:27	clojurebot	([0 1] [1 2] [2 3] [3 4] [4 5])
21:28	brehaut	pppaul: the keyword function
21:28	gfrlog	,(keyword "jack")
21:28	clojurebot	java.lang.StackOverflowError
21:28	pppaul	oooooooooh
21:28	gfrlog	,(keyword "jack")
21:28	clojurebot	:jack
21:28	pppaul	damn i'm tired
21:28	amalloy	&(map (juxt identity inc) (range 5))
21:28	sexpbot	⟹ ([0 1] [1 2] [2 3] [3 4] [4 5])
21:28	pppaul	:P
21:28	gfrlog	amalloy: I agree, I was trying to do a trivial use of (for)
21:28	amalloy	kk
21:29	gfrlog	It's juxt what I was trying to use for for
21:30	Kowboy	,(for [[k v] {:id 12 :name "Bob"}] {k v} )
21:30	clojurebot	({:id 12} {:name "Bob"})
21:30	Kowboy	still, I'd use a vector instead
21:30	gfrlog	I'd use a java.util.HashMap<String, String>
21:30	brehaut	pppaul: http://clojuredocs.org/clojure_core/clojure.core/for go read that
21:31	amalloy	gfrlog: barf
21:31	Kowboy	,(for [x {:id 12 :name "Bob"} ] x)
21:31	clojurebot	([:id 12] [:name "Bob"])
21:32	pppaul	reading
21:34	Kowboy	now I'm confusing myself on how map and for are different
21:35	amalloy	Kowboy: they treat multiple sequences differently
21:36	brehaut	pppaul: there are a couple of major uses: if you are doing multiple maps and/or filters for really tidys things up, and if you want the cross product of two or more collections
21:36	Kowboy	and for takes an expression/form while map takes a function?
21:36	brehaut	pppaul: the first example on that page shows a map and filter occuring in the same comprehension
21:36	amalloy	Kowboy: sure, that's mostly syntax sugar
21:36	brehaut	the second and third examples are crossproduces
21:37	brehaut	Kowboy: for has more in common with mapcat than with map
21:37	brehaut	Kowboy: it happens that when there is only a single sequence, it looks like map
21:38	arohner	has anyone used cron4j? Is it any good?
21:39	Kowboy	ok, found my equivalent expressions:
21:39	Kowboy	,(map (fn [x] x) {:id 12 :name "Bob"})
21:39	clojurebot	([:id 12] [:name "Bob"])
21:39	Kowboy	,(for [x {:id 12 :name "Bob"} ] x)
21:39	clojurebot	([:id 12] [:name "Bob"])
21:39	Kowboy	not sure if my map version can be done more simply
21:40	brehaut	Kowboy: use identity instead of (fn [x] x)
21:41	amalloy	brehaut: or vec
21:43	Kowboy	,(== (map identity {:id 12 :name "Bob"}) (for [x {:id 12 :name "Bob"} ] x))
21:43	clojurebot	java.lang.ClassCastException: clojure.lang.LazySeq cannot be cast to java.lang.Number
21:44	Kowboy	darn
21:44	amalloy	Kowboy: =, not ==
21:45	Kowboy	,(= (map identity {:id 12 :name "Bob"}) (for [x {:id 12 :name "Bob"} ] x))
21:45	clojurebot	true
21:45	Kowboy	wait, isn't = the assignment operator?
21:46	Kowboy	:-)
21:52	amalloy	at least clojure doesn't have ===
21:56	Kowboy	=== is for when you REALLY mean it
21:57	Kowboy	that's it, I'm going to define === and add it to the clojure.core ns
21:57	shachaf	Kowboy: And redefine == to randomly return the wrong answer 10% of the time.
21:59	Kowboy	brilliant!
21:59	TimMc	It's not random! :-(
21:59	TimMc	I can't speak for PHP, though.
21:59	Kowboy	how about !!=
22:00	Kowboy	the not-not-equal operator
22:00	amalloy	TimMc: php's implicit type conversions are even worse than javascript's, which are abominable
22:00	TimMc	amalloy: I think JS's == is not even transitive, which is awesome.
22:03	amalloy	really? e.g.?
22:04	TimMc	Ugh, can't find it now...
22:04	TimMc	I'll get back to you if I can reproduce it.
22:05	TimMc	amalloy: OK, here we go: '00' == 0 == '0'
22:05	TimMc	but '00' != '0'
22:05	amalloy	nice
22:06	TimMc	I had forgotten that JS did string parsing for integer equality. Yuck.
22:07	amalloy	TimMc: in php: '00' == 0 == 'ojhgfklh'
22:08	TimMc	(defn == [a b] true)
22:10	rata_	hahaahaha
22:10	rata_	how do you change the size of the slime history?
22:12	gfrlog	barfbag2273
22:21	pdk	(doc read-line)
22:21	clojurebot	"([]); Reads the next line from stream that is the current value of in ."
22:30	Kowboy	ok, I have a tough one
22:30	Kowboy	I want a macro that can generate multiple functions
22:31	Kowboy	(make-call {:char-list "/chars" :foo "/foo" :bar "/bar" })
22:31	Kowboy	to result in definitions like: (defn foo [] (println "/foo"))
22:31	tomoj	if there are no more arguments, may I suggest dropping the {}?
22:31	Kowboy	but for each pair in the map
22:31	Kowboy	ok
22:32	tomoj	not that it matters much..
22:32	Kowboy	and bind them using let?
22:32	Kowboy	or for, rather
22:33	Kowboy	I actually am close
22:33	tomoj	no, just (defmacro make-call [& {:as foo}]) or whatever
22:33	Kowboy	right now, I get my defn's wrapped in a list
22:33	tomoj	just stick a 'do at the head
22:34	Kowboy	hmm...i tried that, maybe I did something wrong there
22:34	Kowboy	I know what I did
22:34	Kowboy	I should have done (list 'do ....
22:34	Kowboy	I just did ('do
22:35	tomoj	list* is often useful in situations like that
22:35	Kowboy	,(doc list*)
22:35	clojurebot	"([args] [a args] [a b args] [a b c args] [a b c d & more]); Creates a new list containing the items prepended to the rest, the last of which will be treated as a sequence."
22:36	tomoj	,(list* 'do (for [[k v] {:foo 3 :bar 4}] `(def ~k ~v)))
22:36	clojurebot	DENIED
22:36	tomoj	huh
22:36	tomoj	oh, of course
22:37	tomoj	,(list* 'do (for [[k v] {:foo 3 :bar 4}] `(poop ~k ~v)))
22:37	clojurebot	(do (sandbox/poop :foo 3) (sandbox/poop :bar 4))
22:38	Kowboy	hah, it works!
22:38	Kowboy	thanks
22:41	Kowboy	tomoj: trying to strip the {}
22:41	amalloy	`(do ~@body) is a common idiom
22:41	Kowboy	so [& args]
22:41	Kowboy	how to I bind that to pairs?
22:42	amalloy	Kowboy: with the {} :P
22:42	tomoj	pff
22:42	amalloy	or if you really prefer it, you can (partition 2 args)
22:43	tomoj	I guess you probably don't want {:as crap} in your arglist
22:43	amalloy	&(partition 2 [1 2 3 4 5 6])
22:43	sexpbot	⟹ ((1 2) (3 4) (5 6))
22:43	Kowboy	(make-call :foo "/foo" :bar "/bar")
22:44	Kowboy	so I need to iterate over the args in pairs
22:44	Kowboy	not seeing it
22:44	tomoj	well destructuring can do it for you
22:45	tomoj	..better not though
22:46	amalloy	&(let [args [:foo "/foo" :bar "/bar"]] `(do ~(map str (partition 2 args))))
22:46	sexpbot	⟹ (do ("clojure.lang.LazySeq@5d847e33" "clojure.lang.LazySeq@5d2b26fe"))
22:46	amalloy	&(let [args [:foo "/foo" :bar "/bar"]] `(do ~(map (partial apply str) (partition 2 args))))
22:46	sexpbot	⟹ (do (":foo/foo" ":bar/bar"))
22:47	amalloy	whoops, forgot the @ in ~@
22:48	tomoj	you prefer `(do ~@x) to (list* 'do x)?
22:48	Kowboy	ok, I get the :as option now
22:48	Kowboy	[& {:as calls}]
22:49	amalloy	tomoj: not especially. but (cons 'do x) is better
22:49	amalloy	if you're going to do without `
22:50	tomoj	core.clj confirms this spectacularly
22:50	tomoj	(if name (list* 'fn* name new-sigs) (cons 'fn* new-sigs))
22:50	amalloy	heh
22:52	tomoj	has bit-seq left anyone else seriously confused?
22:52	amalloy	&(doc bit-seq)
22:52	sexpbot	java.lang.Exception: Unable to resolve var: bit-seq in this context
22:52	tomoj	from gloss, I should say
22:52	Kowboy	so, basically I am deciding whether to use a macro, or currying for my needs
22:52	Kowboy	they accomplish the same thing, with the macro approach being more DRY and the currying approach being a little clearer
22:53	Kowboy	I am defining groups of functions which have similar arg lists, but each function is specifying one of the args
22:56	amalloy	Kowboy: i don't follow
22:57	Kowboy	instead of this: (geturl "/foo" 1 2 3) (geturl "/blah" 1 2 3), etc....
22:57	Kowboy	I'm turning that into (foo 1 2 3) and (blah 1 2 3)
22:57	Kowboy	so, using currying
22:58	Kowboy	(def foo (partial geturl "/foo"))
22:58	brehaut	Kowboy: thats not currying
22:58	brehaut	thats partial application
22:58	Kowboy	I thought it was the same thing
22:58	brehaut	no
22:58	Kowboy	close?
22:58	amalloy	they're related, anyway
22:59	brehaut	implict partial application is a property of curried functions
22:59	TimMc	I don't think you can have currying and variadic functions in the same language.
22:59	brehaut	TimMc: should i point you to the printf implemention in haskell?
23:00	brehaut	canonical example: (fn [a b c] (…)) curried would be
23:00	TimMc	brehaut: How does it know when to stop?
23:00	brehaut	(fn [a] (fn [b] (fn [c] (…)))
23:00	amalloy	TimMc: someone posted automatic currying of non-variadic defns on the clojure ng a month or two ago
23:00	brehaut	TimMc: the magic of type classes
23:00	TimMc	brehaut: Hrmf. GO figure, it's more Haskell magic. :-P
23:00	Kowboy	still not sure I see the difference
23:01	brehaut	Kowboy: the former would be called as (f 1 2 3)
23:01	brehaut	the latter as (((f 1) 2) 3)
23:01	Kowboy	ok, so currying is a chain of functions with a single argument
23:01	brehaut	yes
23:02	brehaut	well
23:02	brehaut	a curried function is
23:02	Kowboy	subtle difference
23:02	brehaut	yes
23:02	brehaut	but its important
23:03	brehaut	you can have partial application without currying, but in a language with proper curried functions there are a lot of optimisations that can be made
23:03	brehaut	[end of curry/partial rant]
23:04	amalloy	brehaut: don't proclaim that so soon
23:04	Kowboy	ok, so back to my decision, macros vs. partially applied functions
23:04	Kowboy	(def foo (partial geturl "/foo"))
23:04	Kowboy	vs
23:04	Kowboy	(make-call :foo "/foo" :bar "/bar")
23:05	Kowboy	any thoughts?
23:05	amalloy	Kowboy: they both sound kinda crazy to me tbh
23:05	TimMc	I have heard "avoid using macros when functions will do" as good Clojure style.
23:05	brehaut	haskell printf btw http://hackage.haskell.org/packages/archive/base/latest/doc/html/Text-Printf.html#v:printf
23:05	TimMc	Not sure if that's just for debugging difficulty, readability, or what.
23:05	Kowboy	well, I would be doing a lot of code duplication otherwise
23:06	amalloy	TimMc: and reusability/composability
23:07	TimMc	ooh, composability, right
23:07	Kowboy	the only reason to use partially applied functions is to avoid having to state the parameter list over and over again
23:07	TimMc	brehaut: Ohhh, does it know when to stop by reading the format string?
23:07	brehaut	TimMc: in this case yes but also magic ;)
23:07	TimMc	haha
23:07	TimMc	Of course magic.
23:08	Kowboy	magic - it's a feature of the language
23:11	brehaut	the primary piece of magic is actually 'pretty simple'; type classes can be polymorphic on the return type of functions
23:12	Kowboy	haven't learned Haskell yet
23:12	Kowboy	will someday, though
23:12	Kowboy	it's on my list
23:14	amalloy	Kowboy: i just don't think you need to do any top-level defs to get the partial/curried versions of your functions
23:14	amalloy	the eventual result you want is like (partial (partial (partial (partial get-url "/foo") 1) 10) 12), right?
23:15	amalloy	that looks like a job for reduce
23:16	Kowboy	sorry, the args after the url are parameters to a web service
23:16	amalloy	(reduce partial get-url ["/foo" 1 10 12])
23:16	Kowboy	I just used integers for readability
23:17	Kowboy	ie, (get-url "/foo" username password account-num)
23:18	amalloy	Kowboy: uh-huh...the type of the args doesn't really matter
23:18	Kowboy	so I'm making methods like (foo username password account-num)
23:18	Kowboy	and (bar username password account-num)
23:19	Kowboy	well, hell, why don't I just link the code ;-)
23:22	Kowboy	https://bitbucket.org/craigmcdaniel/clojureve/src/039d3260328f/src/clojureve/api.clj
23:22	Kowboy	this is my first attempt at useful clojure code
23:23	Kowboy	so be gentle ;-)
23:23	technomancy	clojurebot: arrows is http://ro-che.info/ccc/12.html
23:23	clojurebot	Ok.
23:25	amalloy	Kowboy: my point is why are you def-ing these to vars in the first place?
23:26	Kowboy	as opposed to?
23:28	amalloy	(def account-calls (into {} (for [[name url] {"character-list" "CharacterList" ...}] {name (partial account-call (str "/account/" url ".xml.aspx"))})))
23:29	amalloy	i mean, your service is going to be going through a list of account-based calls anyway, and looking through vars won't do it any good - it will want a map or a multimethod anyway
23:30	Raynes	I was going to be clever and say "Your first mistake is using Mercurial." but decided against it, because I'm a nice guy.
23:31	Kowboy	I guess there's not much of an Emacs vs Vim flame here, so you have to go for the git vs Mercurial ;-)
23:31	brehaut	Raynes: you are only allowed to use that joke with people still using svn
23:31	Raynes	Kowboy: Don't tell me you're using Vim as well? God, I wont be able to contain myself.
23:32	Kowboy	no, I'm using emacs
23:32	Raynes	Highest of fives.
23:32	brehaut	Raynes: yeah he uses vi, hg, win, and lein
23:32	amalloy	hahaha
23:32	Kowboy	is there a lein debate?
23:32	amalloy	Kowboy: lein/cake
23:32	TimMc	It is the only sexp-aware editor I could find that uses C-s for save. :-P
23:32	brehaut	Kowboy: raynes is young and polarised :P
23:33	Kowboy	I know the type
23:33	brehaut	Kowboy: yeah, any nerd under the age of 55
23:33	brehaut	the ones over 55 arent polarised, just stuck in their ways
23:33	Kowboy	hey!
23:33	Kowboy	I must be between the 2 then ;-)
23:34	Kowboy	I see your point amalloy
23:34	Kowboy	but I'm writing an api others may use, and I think they may only care about a subset of the functions
23:35	Kowboy	in which case they will probably want to call the functions by name
23:35	amalloy	Kowboy: i don't see why. they can write ((account-call "character-list") more-args)
23:36	amalloy	and if you want, you can wrap that up in some defns with a macro
23:36	Kowboy	hmmm
23:36	amalloy	but the underlying functionality should be a map or a multi or something
23:37	Kowboy	a multi doesn't fit here does it?
23:37	Kowboy	unless you are talking about the different types of calls
23:37	amalloy	meh, i guess not
23:37	Kowboy	account, anonymous, character, etc
23:38	amalloy	yeah multi doesn't make a lot of sense here
23:38	Kowboy	I could wrap all those into one api call with multis
23:38	amalloy	but a map!
23:43	Kowboy	(derive ::character-list ::account-call)
23:43	Kowboy	I could use something like that for the dispatching
23:43	amalloy	Kowboy: maybe so
23:44	defn	http://clojuredocs.org/clojure_core/clojure.java.io/file
23:44	defn	what's up with the http:/asdf.com ?
23:45	defn	(the single slash)
23:45	Kowboy	I just recently learned about multis, so I may explore that
23:46	Kowboy	is there a shortcut version (macro) for derive that associates multiple child tags with a parent?
23:46	amalloy	Kowboy: just use doseq. you don't need a specific macro
23:46	Kowboy	wouldn't be much to write one
23:47	Kowboy	k
23:47	amalloy	it definitely shouldn't be a macro. a function is more than enough
23:47	Kowboy	yeah, not much to it really
23:48	Kowboy	just seems like something that would be pretty common
23:48	amalloy	Kowboy: not as far as i've seen
23:49	amalloy	if you're defining a multi you usually expect methods to come from all over, so having a way to consolidate is not useful most of the time
23:50	Kowboy	you lost me there
23:52	amalloy	multimethods let anyone add methods at any time
23:52	brehaut	a multimethod that is not open to extension is probably better served by (say) cond
23:54	tomoj	defn: ##(.getPath (java.io.File. "foo//bar"))
23:54	sexpbot	⟹ "foo/bar"
23:54	tomoj	&(.getParent (java.io.File. "http://google.com"))
23:54	sexpbot	⟹ "http:"
23:54	tomoj	should be removed from the example as it's terribly misleading
23:54	amalloy	haha tomoj that is awful
23:57	amalloy	brehaut: more likely case or a raw map than cond, but i agree with your general point
23:58	amalloy	(not surprising since you were kindly making my point for me)
23:58	Kowboy	ok, chat with you guys later