#clojure – 2012-11-16

2012-11-16

00:34	Sgeo	Is it safe to say that a + b - b might not = a when using floats?
00:52	pyrtsa	Sgeo: Yes.
00:57	amalloy	Sgeo: a = 1e-20, b=1e20 is an easy case
00:58	Sgeo	I wonder if there cases that might come up in a 3d world that uses floats for locations
00:59	Sgeo	Beyond the fun shakiness further out in the world
00:59	amalloy	or b∈{NaN, ∞, -∞}
01:00	Sgeo	Can I have two namespaces each of which uses a var defined in the other?
01:00	ivan	probably with resolve
01:00	Sgeo	Without resolve, I mean
01:01	cshell	circular deps?
01:01	amalloy	well, yes and no. you can't use the vars directly, but they can be passed in from some third namespace that depends on both of those
01:01	Sgeo	:/
01:02	Sgeo	Eh, my usecase is literally just one def that I could easily rewrite
01:02	Sgeo	in the other namespace
01:10	rattboi	bbloom: I'm having issues w/ the code you posted. The inner let defines grid, but then it is attempted to be used outside the let.
01:16	mindbender1	,(set? {1 1})
01:18	ivan	&(set? {1 1})
01:18	lazybot	⇒ false
01:18	ivan	&(set? #{1 1})
01:18	lazybot	java.lang.IllegalArgumentException: Duplicate key: 1
01:19	mindbender1	(set {1 2})
01:19	mindbender1	&(set {1 2})
01:19	lazybot	⇒ #{[1 2]}
01:19	mindbender1	i think this is inconsistent
01:20	ivan	you're passing a map to set
01:20	mindbender1	yes
01:20	ivan	&(set {1 2 3 4})
01:20	lazybot	⇒ #{[3 4] [1 2]}
01:20	metellus	&(vec {1 2 3 4})
01:20	lazybot	⇒ [[1 2] [3 4]]
01:22	mindbender1	#{{1 2}} => #{{1 2}} but (set {1 2}) => #{[1 2]}
01:23	mindbender1	&(type (first (set {1 2})))
01:23	lazybot	⇒ clojure.lang.MapEntry
01:23	mindbender1	ok
01:23	bbloom	rattboi: d'oh sorry
01:25	bbloom	rattboi: but it's an easy fix, move the vector into the comprehension https://www.refheap.com/paste/6767
01:25	amalloy	mindbender1: you're making it unnecessarily complicated. (set x) doesn't create a new set containing the element x, it creates a set containing each element of x
01:25	mindbender1	amalloy: example?
01:25	amalloy	&(set 1)
01:25	lazybot	java.lang.IllegalArgumentException: Don't know how to create ISeq from: java.lang.Long
01:26	amalloy	&(set [1])
01:26	lazybot	⇒ #{1}
01:26	mindbender1	I passed a map
01:26	mindbender1	not a list
01:26	metellus	maps are key,val pairs
01:26	mindbender1	ok, a list of pair
01:27	mindbender1	thanks
01:28	Sgeo	,`foobar/baz
01:28	rattboi	bbloom: awesome. I'm finally getting somewhere :)
01:28	Sgeo	&`foobar
01:28	lazybot	⇒ clojure.core/foobar
01:28	Sgeo	&`foobar/baz
01:28	lazybot	⇒ foobar/baz
02:13	amalloy	does anyone know what IRC channels ztellman hangs out in? i thought he had #lamina or something, but that's empty
02:52	alex_baranosky	are sorted-maps quicker to do lookups in?
02:53	amalloy	slower, usually
02:58	bbloom	alex_baranosky: the advantage of sorted-maps is the ability to use subseq on them and walk a key range -- it's an index
02:58	bbloom	alex_baranosky: similarly for sorted sets
02:59	bbloom	amalloy: also, aren't tree maps generally more space efficient?
02:59	alex_baranosky	generally indexed things are quicker to do lookups from, is that also true of sorted-map?
03:00	amalloy	they might be smaller, i suppose. i doubt it's a noticeable fraction of the total size
03:00	bbloom	alex_baranosky: hash-maps have unsorted keys and O(1) complexity lookups. tree-maps have sorted keys and logarithmic complexity
03:00	alex_baranosky	bbloom: thanks for the info
03:01	bbloom	although i may be wrong about O(1) for the immutable hash maps in clojure
03:01	bbloom	my data structures are a little rusty :-)
03:01	bbloom	alex_baranosky: but yeah, if you need to do a prefix match or something, you can use a sorted map
03:02	bbloom	alex_baranosky: or if you want to walk the keys started from a particular entry
03:02	bbloom	&(doc subseq)
03:02	lazybot	⇒ ------------------------- clojure.core/subseq ([sc test key] [sc start-test start-key end-test end-key]) sc must be a sorted collection, test(s) one of <, <=, > or >=. Returns a seq of those entries with keys ek for which (test (.. sc comparator (compare ek key)) 0) is true nil
03:03	alex_baranosky	bbloom: I plan to create a lookup table where the key is [start-timestamp end-timestamp] and the value is the result of a calculation.
03:03	amalloy	bbloom: clojure's hash maps are O(log32(n)), which for any value of n that can fit in a computer is a small integer
03:04	bbloom	amalloy: i figured: i knew they were red black trees, which means logs of course
03:04	bbloom	tree screams log :-)
03:04	bbloom	alex_baranosky: do you plan to look up by an exact key match?
03:05	amalloy	huh? you asked about hash maps, and i answered hash maps, which are not red/black
03:05	bbloom	amalloy: gah, sorry
03:05	alex_baranosky	bbloom: yeah, exact match, so sounds like hash-maps will be good for me here, right?
03:05	bbloom	right, that's the default type of map
03:06	bbloom	amalloy: the hash maps are trie's right?
03:07	amalloy	yes, although the difference between a trie and a tree has never made sense to me
03:07	alex_baranosky	bbloom: yep, I'm not that noon :)
03:08	bbloom	heh, trie just means a prefix tree
03:08	bbloom	afaict
03:08	amalloy	oh, does it? that's simple enough then
03:08	bbloom	amalloy: http://en.wikipedia.org/wiki/Trie
03:08	alex_baranosky	are you two at the COnj this yeaR?
03:08	bbloom	i won't be
03:09	alex_baranosky	I almost decided to come, but chickened out of paying for it :)
03:09	amalloy	no
03:10	alex_baranosky	I should plan harder for next year
03:10	amalloy	if i were at the conj i definitely would not be on irc at this hour
03:10	alex_baranosky	amalloy: good point
03:11	bbloom	since we're talking data structures, i'm gonna out the results of my wikipedia-ing for the sake of my own memory
03:11	bbloom	typical mutable unsorted maps are hash tables, which do have O(1) lookups
03:12	bbloom	trees, by their nature, provide log lookups
03:12	bbloom	clojure's hash-map is a trie, since it is assumed that hash codes will be uniformly distributed, the tree should be well balanced
03:12	bbloom	tries are just prefix trees, which is fundamentally the same thing as a sorted tree
03:12	bbloom	but clojure's sorted-map is a red black tree
03:12	bbloom	which is a special kind of sorted binary tree that is self balancing
03:13	bbloom	that's the interesting bit: since the keys can be anything (ie non uniform) then you need to pay some extra cost for balancing the tree
03:13	bbloom	so RE: the memory usage amalloy, i doubt the sorted maps are more memory efficient
03:14	bbloom	it would likely be true that a mutable TreeMap would be more memory efficient than a mutable HashMap
03:14	bbloom	but i have to assume that red black trees have the same complexity, but larger constants in both time and space when compared to tries
03:14	bbloom	hopefully that makes sense / is correct :-)
06:04	Chiron	Hi guys, would you please have a look at https://groups.google.com/forum/?fromgroups=#!topic/clojure/3XkAhC7gUP8 ?
06:07	clgv	Chiron: is that your question?
06:08	Chiron	yes
06:08	clgv	have a look at the doc of `tree-seq`
06:09	Chiron	i did, but i don't really understand how to use it in my case
06:10	Chiron	i didn't get why the guy who answered, used map? function
06:12	clgv	,(doc tree-seq)
06:12	clgv	&(doc tree-seq)
06:12	lazybot	⇒ ------------------------- clojure.core/tree-seq ([branch? children root]) Returns a lazy sequence of the nodes in a tree, via a depth-first walk. branch? must be a fn of one arg that returns true if passed a node that can have children (but may not). ch... https://www.refheap.com/paste/6773
06:12	clgv	as you see there, he uses `map?` as the function that decides when to branch.
06:13	clgv	so that function will call the children function on every map of that tree structure
06:14	Chiron	yes but in my snippet, i didn't mention any thing about maps .
06:15	clgv	you did. you had the following keyword access: (:children input)
06:15	Chiron	hmmm
06:15	Chiron	true
06:17	clgv	so if you had a tree of maps you could use laurents suggestion. if you have something similar but not build of maps then you can adapt that sugggestion
06:17	Chiron	my original snippet is ok ?
06:17	Chiron	the very first post
06:19	clgv	without context yes.
06:20	Chiron	can i change (tree-seq map? :children input) to something like (tree-seq is-instance-of-class2 :children input) ?
06:21	Chiron	so if it is instance of class 2 , call :children , if not , do nothing , just pass it to the result seq
06:21	clgv	why don't you try? ;)
06:22	Chiron	well true, just chatting :)
06:23	Chiron	just one more thing please, my original snippet . it is not going to consume the stack and throw stack overflow in some cases ?
06:24	clgv	yes it will
06:25	clgv	it consumes stack, but if your tree is not too deep you probably wont get a stack overflow
06:25	Chiron	i see
06:27	clgv	just try it with representative worst case data
06:29	Chiron	oki
06:29	Chiron	thanks!
07:26	mpenet	ibdknox: in jayq.util/clj->js is there a specific reason for using coll? instead of sequential? (even tho there is a check for maps before, the later would seem more appropriate)?
08:01	jweiss	i'm trying to figure out why i can change the print-method for a function object using ^{:type ::foo} metadata, and this also changes the dispatch for pprint. but if i do the same thing for a vector, it only affects prn, not pprint.
08:08	tgoossens	is it idiomatic to use java enums in clojure. Or do you just give a keyword (which i think is allright)
08:08	tgoossens	concrete example. In clojure i'm making some kind of game. A "robot" can have an orientation (north, west, etc)
08:09	tgoossens	in java i would use an ENUM for that orientation
08:09	tgoossens	but in clojure
08:09	ucb	tgoossens: keywords or symbols are most idiomatic I'd say
08:09	tgoossens	i just used :north, :south, etc
08:09	ucb	tgoossens: especially keywords
08:09	tgoossens	which i think is fine
08:09	tgoossens	just wanted a 2nd opinion
08:09	ucb	I'd +1 keywords
08:09	ucb	tgoossens: I've also seen people use symbols directly, which is also fine
08:11	tgoossens	hmm
08:11	tgoossens	keywoards are clearer i think
08:12	tgoossens	you can see that it is not a function
08:12	ucb	oh, I understand that, I'm only saying what I've seen done
08:12	tgoossens	oh yeah
08:12	tgoossens	one thing
08:12	tgoossens	turning clockwise
08:12	tgoossens	:north -> :east , :east -> :south etc
08:12	tgoossens	counter clockwise
08:13	tgoossens	is the inverse mapping
08:13	tgoossens	currently i have
08:13	tgoossens	(inverse-orientation :north) -> :south
08:13	tgoossens	(anticlockwise : north ) == (inversre-orientation (clockwise :north))
08:14	tgoossens	is that ok. Or should I use some kind of bimap (not sure if that exists)
08:15	ucb	tgoossens: the inverse orientation and rotation are two different things; I wouldn't conflate them together
08:15	ucb	maybe I'd have (inverse :nort) ; :south
08:15	ucb	and (rotate-right :nort) ; :east
08:15	tgoossens	hmm
08:16	ucb	unless you want (inverse ...) to be (rotate 180 ...)
08:17	tgoossens	got to go : ( (college)
08:17	tgoossens	thanks already
08:18	ucb	no worries
08:44	borkdude	I had an idea, but realized this idea must have come up before. Some people like LaTeX because what comes out of it looks beautiful. The LaTeX code itself isn't really beautiful, but the end results justifies it. What about applying the same approach to Clojure? So typing it in one half of the instarepl results in nicely looking code (without lots of parens) on the right?
08:45	borkdude	Not that I hate parens, but Clojure code could maybe be formatted into something more beautiful looking
08:47	borkdude	ibdknox maybe this is a cool idea for lighttable?
08:50	Scriptor	borkdude: it's a matter of just getting used to it :)
08:51	Scriptor	the parens are nowhere near as jarring as they used to be for me
08:51	borkdude	Scriptor don't get me wrong, I am used to it. Common Lisp since 2004, Clojure from 2009 on
08:51	Scriptor	ah
08:52	Scriptor	could it be done just by modifying the syntax highlighting?
08:52	lucian	i've pondered whether something more like yaml for data structure could work for a homoiconic language without redundant separators
08:52	Scriptor	or would it rearrange the code as well (for better whitespace and whatnot)
08:52	borkdude	Scriptor but being able to view the code in multiple ways, like in a LaTeX-ish pseudocode mathematics book kind of style could be nice
08:53	lucian	there's sweet-expressions for schemes, but it does too much i feel
08:53	Scriptor	hmm
08:55	borkdude	emacs does this already (in some modes?) by replacing fn with the lambda sign
08:56	lucian	for me, the redundancy between parens and indentation is the annoying bit
08:56	lucian	i have the same feeling when i write in a { } language
08:56	Scriptor	whitespace-aware lisp has been done before
09:06	borkdude	gtg
09:11	ivenkys	gents - (defmulti encounter (fn [x y] [(:Species x) (:Species y)])) - what is :Species in this ?
09:14	ivenkys	i understand encounter is a multi-method and takes a function with 2 args as params - but i dont get what :Species does here
09:47	andrewmcveigh\|wo	ivenkys: :Species is just a keyword there.
09:48	Bronsa	but it's being used as a function
09:48	Bronsa	so (:a x) is just like (get x :a)
09:48	andrewmcveigh\|wo	Bronsa: indeed, keywords can act as functions
09:48	ivenkys	andrewmcveigh\|wo: Bronsa : does this mean the "assumption" here is that fn takes two maps as params ?
09:49	Bronsa	yes
09:49	andrewmcveigh\|wo	yep.
09:49	Bronsa	well, more generally, a clojure.lang.ILookup i think
09:49	ivenkys	Bronsa: andrewmcveigh\|wo : that was the missing link - thanks gents
10:11	TimMc	,(- Double/POSITIVE_INFINITY Double/POSITIVE_INFINITY)
10:12	Iceland_jack	&(- Double/POSITIVE_INFINITY Double/POSITIVE_INFINITY)
10:12	lazybot	⇒ NaN
10:44	TimMc	ivenkys: Don't assume gender.
10:48	duck1123	Bmt^MOBv
10:48	duck1123	at least that wasn't all the password
11:07	scottj	has anyone seen any summaries/notes on rich's keynote?
11:25	clgv	&(+ Double/POSITIVE_INFINITY Double/POSITIVE_INFINITY)
11:25	lazybot	⇒ Infinity
11:32	seangrove	Any word on whether Domina elements can be passed to the google closure library?
11:35	seangrove	It seems that Domina elements are a special object in Javascript, and the Google Closure libraries are expecting standard html elements
11:37	seangrove	Ah, need to use domina/single-node
11:43	Stooge	hello :)
11:43	mjwhitt	greetings :)
11:44	Stooge	do you have any good tutorials/books/video clips/exercises for beginners?
11:45	joro	Stooge: I'll recommend http://www.clojurebook.com/, and then experimenting with repl using (doc and (source
11:46	Stooge	thanks :)
11:53	TimMc	Stooge: http://clojure-doc.org/ is also coming along
11:54	TimMc	Most pages aren't complete yet, but there's already some really good stuff.
11:55	Stooge	you mean there are lots of undocumented functions? :p
11:56	AdmiralBumbleBee	Stooge: are you willing to buy a book?
11:56	Stooge	ofc not :)
11:56	Stooge	i need money :)
11:57	AdmiralBumbleBee	http://java.ociweb.com/mark/clojure/article.html
11:57	AdmiralBumbleBee	that's where I started
11:57	seangrove	Goodness me, the google closure library does not lend itself well to clojure idioms
11:57	seangrove	More and more impressed with the approach of Domina
11:58	Stooge	k
12:00	joro	Do you use Clojure in your daily work?
12:03	duck1123	I tried using Domina, but I had issues with one of the goog.dom namespaces or something. (this was a while ago) I've been using Jayq/jquery. Is there anything that domina offers that might make it worth switching?
12:04	Stooge	duck1123 ? :P is this related to closure at all? :p
12:06	duck1123	Domina and Jayq are Clojurescript libraries.
12:06	Stooge	k sorry :P
12:06	Stooge	never heard about them :P
12:06	ivenkys	TimMc: hmm good point - my default assumption might be incorrect - i stand corrected (at least on this channel)
12:06	duck1123	jayq is a wrapper around jquery, domina (IIRC) is a wrapper around the Google Closure dom stuff
12:18	seangrove	duck1123: It does seem to lend itself much more towards clojure idioms, it's tiny, and extendable to lots of other libraries
12:18	seangrove	I've certainly come around to the micro-library approach, domina fits well
12:19	seangrove	But I was using jayq beforehand, which is certainly great as well
12:21	Urthwhyte	Having a StreamClosed error when trying to write out to a file with the following code: https://gist.github.com/5490934e9720abc5b131
12:21	Urthwhyte	am I meant to have a doseq or something?
12:22	hiredman	~map
12:23	hiredman	clojurebot: ping
12:24	alexnixon	Urthwhyte: map returns a lazy sequence, which is evaluated after your with-open scope has closed. So you need to force evaluation before the with-open closes. So yes, doseq would be good here.
12:25	hiredman	clojurebot: ping
12:25	clojurebot	PONG!
12:26	hiredman	sometimes you can just hear the jit spinning
12:26	Urthwhyte	haha
12:26	Urthwhyte	Of course >< - thank you alexnixon
12:39	zodiak	why does compojure destructure a request in a defroute ? is it jst for clarity when defn a route ?
12:40	zodiak	I mean, I understand the functionality, jst wondering the rationale
12:40	mpenet	zodiak: you are free not to do it in the route definition
12:41	zodiak	surely.. I guess I was wondering, why is it even "there" ?
12:41	mpenet	zodiak: it is handly for extremely simple "controller", but gets hairy imho when you need to use a large number of arguments from it
12:41	zodiak	jst so it's not passing a whole hash-map/dict around ?
12:41	zodiak	mpenet, aaahh
12:42	zodiak	so, it's part of keeping the function definition 'concise' or 'clear' to other people ?
12:42	clojurebot	is there a function that is somewhat similar to partition, except that it creates a max number of groups based on a number
12:42	zodiak	as then you know it's using (say) params etc instead of 'large hash-map'
12:42	mpenet	zodiak: yep
12:42	zodiak	mpenet, gotcha :D
12:43	zodiak	(this maybe starting to make sense. vunderbar ;)
12:45	zodiak	clojurebot, I am guessing you would have to write on using partition-by
12:45	clojurebot	Pardon?
12:45	zodiak	bah.. someone talking via bot.. awesome :P
12:49	antoineB	hello, how to use the keyword this in clojurescript?
12:50	sahadev	hello, is this the right place ask clojure newbie questions?
12:50	antoineB	yes
12:52	sahadev	antoineB: thanks. when I run, (take-while #(< % 100) (fib 1 1)), I get all fib numbers less than 100, as expected. However, when add another condition, (take-while #(and (< % 100) (even? %)) (fib 1 1)), I get an empty list as the result. why?
12:53	sahadev	if I rewrite it as (filter even? (take-while #(< % 100) (fib 1 1))), it works as expected.
12:53	metellus	,(fib 1 1)
12:53	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve symbol: fib in this context, compiling:(NO_SOURCE_PATH:0)>
12:53	sahadev	metellus: fib is another function already defined. (defn fib [a b] (cons a (lazy-seq (fib b (+ a b)))))
12:54	metellus	ok, then the first element of the list is 1
12:54	metellus	which is odd, so take-while stops immediately
12:54	antoineB	shachaf: take-while ends when it encouter a false
12:55	mpenet	antoineB: in cljs you can reach this with the this-as macro
12:55	antoineB	shachaf: (filter #(even? %) (take 100 (fib 1 1))
12:56	sahadev	antoineB: the filter solution works. (filter even? (take-while #(< % 100) (fib 1 1)))
12:57	sahadev	but, i would like to understand what's wrong with the take-while solution.
12:57	AndR	sahadev: that's because filter does not stop on false, it takes all members from the collection for which the predicate is true
12:57	AndR	take-while only takes members until it finds one for which the predicate is true
12:57	metellus	,(doc take-while)
12:57	clojurebot	"([pred coll]); Returns a lazy sequence of successive items from coll while (pred item) returns true. pred must be free of side-effects."
12:57	metellus	AndR: you mean until it finds one for which the predicate is false
12:57	AndR	compare: (take-while odd [1 2 3 4 5]) and (filter odd [1 2 3 4 5])
12:57	AndR	yes, sorry :P
12:58	sahadev	I see.
12:58	mpenet	antoineB: (this-as that (jq/val (jq/$ that) ))
12:59	antoineB	mpenet: ok thanks
13:00	mpenet	it's also possible with (js* "this"), but not advised, as js* is an internal thing and could change/disapear
13:01	sjl	Is there a way to make drip work with Leiningen yet?
13:01	sjl	I set the LEIN_JAVA_... thing but drip creates a new JVM every time I run a lein command
13:02	sahadev	thanks all.
13:06	sahadev	I am currently running emacs + nREPL. Using this setup, I can write small snippets in emacs, and execute them using C-c C-e. How do I run the script from the command line?
13:06	sahadev	looking the process list, it looks like the repl is being run by leiningen.
13:07	sahadev	all I want to run is some form of: clojure script.clj
13:09	sahadev	ah, i managed to find the right incantation :)
13:09	babilen	sahadev: You can use "lein run" (cf. https://github.com/technomancy/leiningen/blob/master/doc/TUTORIAL.md) or create an überjar and execute that. Both approaches are discussed in the TUTORIAL
13:11	babilen	sahadev: There are also hacks/tools such as https://github.com/Raynes/lein-bin and other ways... I am sure that other have some suggestions as well.
13:11	sahadev	babilen: thanks.
13:12	babilen	sahadev: All that being said: I haven't yet found a single approach to create well-behaved executables easily
13:13	sahadev	a lot of the docs assume familiarity with java environments. not being a java guy, sometimes I have trouble following things that might be very obvious to a java programmer.
13:13	sahadev	is there a tutorial/doc for "getting started with clojure for non-java programmers"?
13:16	zodiak	sahadev, not really.. but.. to be fair.. clojure is pretty far removed from java in the first place
13:17	babilen	Wasn't there a nice/good "Java for Clojurists" article somewhere?
13:17	sahadev	zodiak: I am not looking for help with the clojure language per se. but, with the environment/toolsets to help me get started quickly.
13:17	babilen	And why is it not possible to query the bots in a /query (they don't answer)
13:18	zodiak	sahadev, I actually found the clojure book by oreilly to be helpful .. but it depends on what you want to do with clojure
13:19	mycelloandi	sahadev: most people use emacs and nrepl or swank for their toolset
13:19	babilen	sahadev: I wouldn't concern myself too much with it for now. You don't need to know much about the Java ecosystem if you use leiningen ... It does help to know the Java standard library though.
13:19	zodiak	if you want web programming, look at compojure and ring. you will bump into leiningen at somepoint (go for lein2)
13:19	babilen	sahadev: I second the recommendation for "Clojure Programming" (http://www.clojurebook.com/) btw
13:19	zodiak	gui I would say seesaw and ignore swing ;)
13:20	sahadev	for example, I have a very simple, short clojure script. and i want to run it from command line. but most of the docs I found talk about tools (like lein) that assume certain things. for example, presence of project.clj, which I am sure is very convenient, if I am working on a real project.
13:20	babilen	So: Is anybody aware of a good way to write command line applications in Clojure?
13:20	zodiak	and I use vim (good old vim ;) for editing .. although some people use eclipse or emacs (same thing! zing)
13:20	babilen	I also use vim (vim vimclojure + lein tarsier) and am very happy with it
13:21	AndR	sahadev: you probably want to make a project for anything you don't do directly from a repl
13:21	mycelloandi	sahadev: "lein run" is the easy way
13:21	zodiak	babilen, I am afraid all I can think of is lein2 uberjar and then the usual java -jar song and dance
13:21	sahadev	zodiak: babilen: I just got the O'Reilley book. looks promising.
13:22	zodiak	sahadev, you will have a learning curve if this is your first lisp
13:22	AndR	sahadev: for a single script, assuming you have clojure.jar somewhere on global classpath, you can say java -cp `path_to_clojre.jar` clojure.main /path/to/script.clj
13:23	zodiak	but, like anything worth doing, it's going to take a while to get into the groove
13:23	babilen	zodiak: I've just stumbled over https://github.com/kumarshantanu/lein-exec but have no idea if it is any good
13:23	sahadev	zodiak: I dabbled a little with emacs-lisp and scheme in the past, but I am very much a newbie when it comes to lisps. but, I am looking forward to learning it.
13:23	babilen	zodiak: I am thinking of something like that combined with a tool such as drip that minimises the pain of starting the program over an over again
13:24	zodiak	babilen, not sure. never used it. sorry.
13:24	sahadev	AndR: that's exactly what I ended up (after pruning most of the options in the lein command line that is running the repl in my emacs session)
13:24	babilen	sahadev: I would recomend to start by reading the leiningen tutorial and to take a look at interesting plugins on https://github.com/technomancy/leiningen/wiki/Plugins
13:25	babilen	gtg, good luck!
13:25	zodiak	sahadev, well.. grab lein (lein2 preferrably since it really is the future), lein2 repl (bring up repl/command line) and then .. read for the most part and play around
13:26	zodiak	remember, inside the repl you can lookup docs (doc str) or search (find-doc "str")
13:26	AndR	sahadev: I recommend making a lein project, doing work with lein repl, then to make the executable do `lein uberjar`, for which you can then do 'drip my.jar' and it should run your main class
13:26	sahadev	zodiak: my "lein --version" says 2.0.0-preview7. that's what you mean by lein2, right?
13:26	AndR	yes
13:26	zodiak	sahadev, yes sir/madam
13:28	zodiak	good show :) any questions, feel free to ask. I don't think there are too many ego's/prima donna's around this channel ;)
13:28	AndR	it seems lein is not integrating cleanly with drip (there are a number of bugs in drip saying so), so `lein run` will not take advantage of drip I'm afraid
13:28	zodiak	jark is another thought, or cake
13:28	zodiak	not that I have ever used either, right enough
13:28	sahadev	zodiak: thanks :) that's encouraging.
13:29	sahadev	what's drip?
13:29	zodiak	sahadev, it's an 'always on' jvm, so when you start your clojure or java program, there isn't a huge wait time in the jvm starting up
13:29	zodiak	basically ;)
13:30	mycelloandi	is drip like nail gun?
13:30	sahadev	ah, i see.
13:30	zodiak	mycelloandi, mostly, yes.
13:31	sahadev	thanks a lot, all. i think i'll be dropping by often.
13:31	zodiak	sahadev, surely.. I would suggest jst idling in here.. never know what you may learn
13:32	sahadev	zodiak: yep. i agree.
13:45	jonasen	I created a lein plugin for codeq: https://github.com/jonase/quantize
13:46	jonasen	If someone would try it and see if it works I'd be thankful
13:54	mudge	Hello, I am trying to use Clojure with a Java Web Start application. By default Clojure uses the context classloader but clojure-1.4.0.jar isn't in there, so I am getting this error: Caused by: java.io.FileNotFoundException: Could not locate clojure/core__init.class or clojure/core.clj on classpath
13:55	mudge	clojure-1.4.0.jar exists in the current classloader not the context classloader. I would set the context classloader to the current classloader, but I don't have control of the Java code to do that.
13:56	mudge	So I'm thinking that I should go into the source of Clojure and change use-context-classloader to false and rebuild Clojure and use that. I'm wondering if that is the best thing to do and if that might cause any problems.
13:57	zodiak	mudge, having been down the clojure webapp and jetty path very recently, have you tried using an uberwar ? it sounds like you are only using a war
13:58	zodiak	(if you get my meaning)
13:58	jodaro	its amazing what rm -rf'ing your ~/.m2 can fix
13:59	mudge	zodiak: I'm building a module for an existing system which has it's own unique installation/deployment scheme. I create jar files and zip them together with a configuration file and then httpPost them to the application.
14:00	zodiak	O_o
14:01	zodiak	mercy.. that's.. urm.. yeah
14:01	mudge	The problem that I have is that my clojure-1.4.0 is in my current classloader and not in my context classloader, but by default Clojure only looks in the context classloader
14:02	zodiak	changing clojure source to fix a (pardon my french) "weird deployment mechanism" is not the ~best~ idea
14:02	mudge	I would set the context classloader to the current classloader by I dont' have access to the Java to do that. So I'm thinking that the only way to do this is to tweak the Clojure source so it doesn't look in the context classloader by default. But not sure if that is the best thing to do or not.
14:02	zodiak	but, that's jst me
14:02	mudge	zodiak: I agree, but I don't know of any other way which is why I'm writing here.
14:07	zodiak	mudge, yeah.. sadly.. I don't know of anyway to do what you want to do :\
14:08	TimMc	zodiak: clojurebot responds to something like 1 in 1000 messages as if it were the target.
14:09	TimMc	with strange results
14:09	zodiak	TimMc, no joke :D
14:12	TimMc	zodiak: And if your message contains " is " or " are " it stores it as a factoid, which then may get triggered by other messages.
14:12	zodiak	O_o
14:12	zodiak	hah!
14:12	zodiak	kinda cool but.. kinda weird :)
14:12	TimMc	Not my idea. :-P
14:13	mudge	Any idea why use-context-classloader is set to true by default?
14:28	mudge	just asked a Clojure question on stackoverflow: http://stackoverflow.com/questions/13423048/why-does-clojure-use-the-context-classloader-by-default
14:33	znDuff	mudge: uhh, the context classloader _is_ the default classloader.
14:33	znDuff	mudge: ...now, why it doesn't always use _that_ is an interesting question. You might find http://stackoverflow.com/questions/10941330/class-forname-in-clojure-not-respecting-contextclassloader (and its answer) worth reading.
14:34	znDuff	mudge: short form: the DynamicClassLoader wrapper Clojure provides is necessary to have a per-namespace bytecode cache, and it has to be stored somewhere.
14:35	znDuff	(provisio: This is from memory, and it was quite a while back that I was actually banging my head on this stuff; memory may have failed a bit since then)
14:36	mudge	znDuff: thanks. What would happen if I changed use-context-classloader to false?
14:38	znDuff	mudge: then you get the classloader that Clojure itself was loaded with
14:38	mudge	znDuff: I'm compiling (with gen-class) a Clojure application and putting it into an existing Java Web Start application and Clojure-1.4.0.jar is not in the context classloader, it is in the current classloader, so having a problem loading any clojure code
14:38	mudge	znDuff: anything bad about that?
14:39	znDuff	mudge: you might want to look at the answer on the SO question I posted a link to. And maybe the question, too.
14:40	mudge	znDuff: I'm thinking of changing use-context-classloader to false in the Clojure source, rebuilding it and using that.
14:41	mudge	Thanks znDuff, that SO post is about what classloader eval uses. It is good to know that eval uses a DynamicClassLoader
14:41	znDuff	mudge: it's not just about eval, that's just what I used to demonstrate.
14:42	mudge	znDuff: I will reread more thoroughly now.
14:47	alex_baranosky	what does ^:constant metadata do ? Anyone got a link to its explanation?
14:48	mudge	znDuff: i don't get what you are trying to say in this comment: but the DynamicClassLoader instance bound to clojure.lang.Compiler/LOADER when clojure.lang.Compiler/eval is called matters.
14:56	znDuff	mudge: Effectively, that comment is duplicative of the answer. Related note: The work that went into that question came out as a patch to clojure.osgi adding support for Apache Felix; if you want to see it in action, that would be https://github.com/charles-dyfis-net/clojure.osgi/blob/master/clojure.osgi/src/main/clojure/clojure/osgi/core.clj
14:56	mudge	ls
14:56	lazybot	boot dev etc lib media mnt root sbin selinux srv usr
14:59	mudge	znDuff: thanks
15:03	mudge	how do I get clojure source for 1.4.0?
15:03	mudge	I go here https://github.com/clojure/clojure but that is for Clojure 1.5.0
15:03	hiredman	git
15:04	raek	mudge: use the 1.4.0 tag
15:04	raek	(instead of the master branch)
15:05	mudge	raek: I see clojure-4.4.0-beta7.zip, would I download that? It's the latest beta version.
15:05	Apage43	https://github.com/clojure/clojure/tree/clojure-1.4.0
15:05	Apage43	https://github.com/clojure/clojure/archive/clojure-1.4.0.zip
15:05	Apage43	if you want a zip
15:05	raek	mudge: if you have clones the repo you already have that tag in your clone
15:06	raek	just do a "git checkout clojure-1.4.0"
15:07	mudge	raek: Apage43: got it, thank you!
15:08	mudge	raek: the tags without alpha and beta in them mean that they are production ready?
15:08	raek	mudge: yes, that's the release version
15:08	mudge	raek: thanks
15:09	raek	usually it's foo-alpha1, fo--alpha2, ..., foo-beta1, foo-beta2, ..., foo-RC1, ..., foo
15:11	Foxboron	Anyone got any great books on learning Clojure which also contains tasks?
15:11	raek	weird that there isn't any obvious browse link for the tags at github...
15:11	znDuff	Foxboron: meaning exercises? Hmm -- the more exercise-focused books are mostly not as good for conceptual learning.
15:12	Foxboron	znDuff, yes exercises, forgot the word there when i typed it ^^
15:12	Foxboron	znDuff, i find it better to read and learn by.
15:12	raek	Foxboron: btw, have you looked at http://www.4clojure.com/ ?
15:12	Foxboron	raek: havent seen it actually
15:13	Urthwhyte	I did about 60 4clojure problems and then switched to reading Programming Clojure
15:14	Urthwhyte	It's really helpful if you follow some of the people topping the leaderboards - some very beautiful (and hideously terse) solutions will give you insight into the language
15:15	Netfeed	is it possible to redifine a function in a module?
15:15	Netfeed	redefine
15:15	Mr_Bond	Netfeed: yes, you can just defun it again
15:15	TimMc	Netfeed: By modfule you mean namespace?
15:16	Netfeed	yes
15:16	Netfeed	even if it's private?
15:16	TimMc	Private only affects what users of that namespace see.
15:17	Netfeed	so it's possible to redefine it from another namespace?
15:17	TimMc	No, you can't do something like (def other.namespace/foo 5).
15:17	Netfeed	too bad
15:17	raek	but you can use 'intern'
15:17	TimMc	You would have to switch over to the other namespace first.
15:18	TimMc	Oh yeah, you could use ns interning.
15:18	TimMc	Sounds like trouble though.
15:18	amalloy	yeah, don't do that. only sadness and spaghetti lies that way
15:18	raek	Netfeed: the real question is why you want to do this, though...
15:19	TimMc	amalloy: That's a good mental image.
15:19	Netfeed	i want to just add some prints to a function in the tower-lib to understand why i get an assert error in it
15:20	TimMc	I think with-redefs might help.
15:20	raek	Netfeed: how are you interacting with clojure? a text-based repl? nrepl/slime?
15:20	amalloy	TimMc: weeping willows with cold pasta draped over their limbs, marinara sauce dripping forlornly to the ground, silent splats nobody can hear
15:21	amalloy	hm. soft splats scans better
15:21	TimMc	D: D: D:
15:22	Netfeed	raek: lein repl i guess
15:23	TimMc	clojurebot: sadness and spaghetti?
15:23	clojurebot	<amalloy> weeping willows with cold pasta draped over their limbs, marinara sauce dripping forlornly to the ground, silent splats nobody can hear
15:23	TimMc	Oops, that doesn't include your edit.
15:24	raek	Netfeed: one way is to modify the defn in an editor, enter the namespace via (in-ns 'foo), paste the new definition in the repl, and then (in-ns 'user) to get back
15:24	raek	this gets much simpler with editor integration
15:26	Netfeed	i'm fairly new to clojure so i'm not really there yet :)
15:26	raek	another way is to download the source to the library, add it as a "checkout" in lein, edit the library source code in your working copy and (require 'the-lib :reload) whenever you have made changes
15:26	Netfeed	with-redefs helped a bit tbh, cool function
15:29	krakoop	hey all... I wrote my first macro (which serves no purpose besides trying macros) and it kinda works as I expected: (defmacro noob [x] `(prewalk-replace {2 :changed} ~x)
15:30	krakoop	when I run this on, say, : (noob '[(print 1 2 3) (((print 2)))]) (once again, this serves no purpose besides trying to understand) I get what I expect: [(print 1 :changed 3) (((print :changed)))]
15:31	TimMc	krakoop: It's not really serving as a macro.
15:31	TimMc	Take off the ` and the ~ and the ' in the input.
15:31	krakoop	however I'd now like to replace not '2' with ':changed' (which works fine) but 'print' with something else. For example I'd like to replace 'print' with 'tst'.
15:31	raek	krakoop: that definition is essentially the same as (defn noob [x] (prewalk-replace {2 :changed} x))
15:32	krakoop	I know, I know. That's not my question. My question is how can I replace not '2' with ':changed' but 'print' with another function name.
15:32	krakoop	; )
15:32	bbloom	krakoop: at the time the macro is evaluated, x is a list
15:32	raek	(prewalk-replace {'print :changed} ...)?
15:33	bbloom	&(let [x '(print :changed)] (cons 'not-print (next x)))
15:33	lazybot	⇒ (not-print :changed)
15:34	bbloom	krakoop: or, with the syntax quote:
15:34	bbloom	&(let [x '(print :changed)] `(not-print ~@(next x)))
15:34	lazybot	⇒ (clojure.core/not-print :changed)
15:34	amalloy	(defmacro noob [x] (prewalk-replace {'print :changed} x)
15:34	krakoop	@raek: {'print :changed 2 :changedtoo} won't work for 'print (but still works for '2')
15:34	amalloy	krakoop: that's because of what TimMc said. your syntax-quote shouldn't be there
15:35	krakoop	ok but what when I want to do the same in case I need the syntax quote too?
15:35	TimMc	I think it should still work...
15:35	raek	krakoop: the ` is interfering... it adds namespace parts to all the symbols
15:35	TimMc	aha
15:35	amalloy	TimMc: no, because `'print is 'clojure.core/print
15:35	amalloy	and also because he's not postwalk-replacing the form itself, but the result of evaluating the form
15:35	TimMc	syntax-quote strikes again!
15:36	raek	krakoop: if you want to experiment with postwalk-replace, start with ordinary functions and pass them quoted code
15:36	krakoop	well the point of my question is kinda precisely to understand syntax quoting etc. ; )
15:37	raek	ah
15:37	raek	well, we can take a look at syntax quote in isolation (you don't have to be in a macro to use it)
15:37	krakoop	@raek: postwalk-replace is not what I'm interested in... a simple 'replace' example would work too: I mean, I'd be just as confused ; )
15:37	raek	,`[(print 1 2 3) (((print 2)))]
15:37	clojurebot	[(clojure.core/print 1 2 3) (((clojure.core/print 2)))]
15:38	raek	this is the value that postwalk-replace received in your example
15:38	krakoop	so how would I modify my map so that it replace print (which is received as clojure.core/print) with something else ?
15:39	amalloy	!!!! no it's not, raek
15:39	raek	amalloy: you are right.
15:39	amalloy	it received [(print 1 2 3) (((print 2)))], but its replace-map was {clojure.core/print :changed}
15:39	amalloy	krakoop: don't syntax-quote it :P
15:39	raek	that makes more sense
15:40	krakoop	amalloy: oooooh gotcha
15:42	estebann	so clojure.java.shell/sh seems to hang if the command run prints too much to stdout... has anyone else seen this or is it just me?
15:43	mudge	zdNuff: I set use-context-classloader to false in RT.java, but now I am getting this error: aused by: java.lang.ClassNotFoundException: clojure.lang.PersistentList
15:44	mudge	seems like Clojure is still looking in the context classloader even though I set use-context-classloader to false
15:47	ebaxt	I'm trying to understand a lazy fibs example: https://gist.github.com/4090592, I
15:47	znDuff	mudge: if you're following the OSGi example, I don't think I ever set use-context-classloader to false there.
15:48	ebaxt	I've tried to break down the state of the execution, and I'm wondering if either A or B is correct=
15:48	ebaxt	?
15:49	mudge	znDuff: I'm not following the OSGi example
15:49	mudge	znDuff: I have a gen-classed class file that I want a Java application to use -- the source of which java I don't have access to.
15:51	Mr_Bond	estebann: how long does it have to be?
15:52	Mr_Bond	,(clojure.java.shell/sh "cat" "/etc/resolv.conf")
15:52	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.ClassNotFoundException: clojure.java.shell>
15:52	estebann	looks like an out of memory exception is failing to bubble up... so bigger than you have heap space
15:52	Mr_Bond	ah, I see
15:53	estebann	you can test it with (clojure.java.shell/sh "cat" "/dev/urandom") pretty easily at least on linux
15:53	Mr_Bond	yeah, good idea
15:55	Mr_Bond	I guess it would be nice to have an alternate interface to sh, which gave a sequence, instead of it having to first fill up "stdout" variable
15:55	estebann	I definitely would appreciate it at the moment
15:58	Mr_Bond	I seems supported by http://docs.oracle.com/javase/7/docs/api/java/lang/Process.html#getInputStream(), so you could write your own "sh" using https://github.com/richhickey/clojure/blob/4bea7a529bb14b99d48758cfaf0d71af0997f0ff/src/clj/clojure/java/shell.clj#L63 but I guess there is probably something in clojure.contrib or in the repos for it
16:00	estebann	cool... should I report this somewhere?
16:00	amalloy	Mr_Bond: see Raynes's conch library. or maybe it's fs? i don't remember which one it's in
16:01	Mr_Bond	estebann: I think it's expected, but otoh it would be nice to have such a tool in core
16:02	Mr_Bond	amalloy: nice
16:02	Mr_Bond	thanks
16:02	estebann	huh.. I would have expected to get the Out Of Memory Error
16:03	estebann	rather than a hung thread
16:03	Mr_Bond	oh, right. Yeah, that's not good
16:04	Mr_Bond	mm, it looks like Raynes.fs/exec could be an option
16:04	amalloy	it's an OOME on a different thread
16:04	Mr_Bond	ah, no it just wraps clojure.java.shell/sh
16:05	amalloy	there's no real way to catch that given the rubbish implementation of sh, as far as i know
16:05	amalloy	Mr_Bond: yeah, you want conch, not fs
16:06	Mr_Bond	cool, yeah thats more like it
16:07	estebann	amalloy: cool, loooks good
16:08	Mr_Bond	there was a link pasted the other day, about a functional programming book (clojure) on PDF, for a couple of bucks
16:08	Mr_Bond	anyone happen to remember the link?
16:27	alex_baranosky	does anyone know what ^:constant metadata does?
16:31	zodiak	alex_baranosky, I ~assume~ the opposite of ^:dynamic
16:31	zodiak	marks it as a var but NOT dynamically rebindable
16:31	zodiak	(guessing here ;)
16:31	alex_baranosky	http://stackoverflow.com/questions/9162558/how-does-clojure-const-work
16:31	TimMc	I think the opposite of ^:dynamic is simply the lack of it.
16:32	alex_baranosky	it changes the way the code gets compiled
16:32	zodiak	TimMc, following the python mantra though, explicit is better than implicit so, having a ^:constant would tell me "whoa, this isn't changeable no way no how"
16:33	zodiak	and anywhere I see ^:constant is with things like pi or tau so .. as I said, guessing :)
16:33	TimMc	THis is a question of reality, not desire.
16:33	TimMc	Oh, I see why you said that.
16:34	zodiak	dynamic would have to be constantly looked up, right ? to check the value, constant should be looked up once (hopefully ;)
16:35	alex_baranosky	its actually ^:const not ^:constant
16:35	alex_baranosky	I got that one wrong
16:36	zodiak	well, shut my mouth then :)
16:37	alex_baranosky	so const attempts to embed the var in the code at compile time
16:37	alex_baranosky	I just attempted to use ^:const on a simple date format, and found out that detail (since the reader/printer don't know how to handle SimpleDateFormats)
16:39	bobry	Folks, how should I debug "Uberjar aborting because jar/compilation failed: java.lang.String cannot be cast to clojure.lang.IFn"?
16:39	bobry	All I have is a file with an empty -main function, which does nothing.
16:40	bobry	So I guess it's not my code which is causing the exception.
16:41	zodiak	bobry, have you tried calling your main from lein repl ?
16:41	bobry	I've tried 'lein run' and it seems to work fine.
16:44	zodiak	time to pastebin.com I reckon
16:45	Foxboron	doing some problems on the clojure4 site. Came to problem 22 where i am suppose to count a list without using count.
16:45	zodiak	fwiw, I almost always use lein repl and then use lib, (main) the sucker
16:45	Foxboron	#(for [x %] :let [y (+ y 1)] [y])
16:45	Foxboron	Why wont this work :3?
16:45	Foxboron	<- total LISP noob
16:47	bobry	okay, this is nice, the problem was in the :license field of the 'project.clj' file, which was "MIT", instead of a hash-map
16:47	znDuff	Foxboron: first, y has no initial binding; second, for loops are like Python list comprehensions, so they aren't really a fit to what you're trying to do here.
16:47	bobry	time for a bug report :)
16:47	AimHere	Foxboron, I think there's about 4 reasons
16:49	znDuff	Foxboron: ...a for loop just creates a lazy sequence -- it doesn't actually force it to be evaluated -- and it doesn't retain state between steps in that loop
16:49	znDuff	Foxboron: as a hint, you might look at loop/recur.
16:49	Foxboron	was going to ask for hints ^^
16:50	Foxboron	Started clojure today and only know Python from before, so its a rather radical change
16:50	zodiak	Foxboron, also the bracketing in the for loop is wrong ;)
16:50	Foxboron	but its actually rather fun
16:50	Foxboron	zodiak i did notice on the second look
16:50	Foxboron	spent 4 hours fixing the leining repl....
16:50	znDuff	Foxboron: ...actually, I said "like Python list comprehensions", but they're actually closer to genexps, in terms of being lazy.
16:51	Foxboron	something bugged with the path and the 2nd version on windows FYI
16:51	raek	Foxboron: when you're using loop and recur, imagine that you are only allowed to update your variables at one point (at the end of the loop)
16:51	Foxboron	znDuff, i havent actually read up what it means by being "lazy", so will look into that aswell :)
16:51	znDuff	Foxboron: Have you tried Light Table for Windows, by the way?
16:51	Foxboron	znDuff, oh damn right.
16:51	Foxboron	I was going to, totally forgot
16:52	Foxboron	another reason why i actually started looking at Clojure, i found the syntax rather pleasant looking at when i watched the demo.
16:52	purpleguy	it is
16:52	purpleguy	the guy who writes it gave a talk just day before yesterday
16:52	purpleguy	here at my uni
16:53	Foxboron	there is a...
16:53	znDuff	purpleguy: I've seen the new version, and I still don't think it's there yet.
16:53	purpleguy	basically, he's got so many features he's implementing
16:53	Foxboron	JavaScript conf going on where they will be presenting some stuff using LightTable
16:53	Foxboron	will be livestreamed
16:53	Foxboron	znDuff, i won't really judge it before its out.
16:53	Foxboron	anyone seen the talk which the concept was based on?
16:54	znDuff	Foxboron: With the interactive game? A great many of us have.
16:54	Foxboron	saw it first time yesterday actually.
16:55	Foxboron	also, what is considered the best site for clojure documentations? i use clojuredocs.org but i find it rather messy and all over the place
16:55	dakrone	Foxboron: there are multiple sites, perhaps try clojure-doc.org or doc.clojure.org
16:55	AimHere	I find that clojure cheat sheet to be the most useful document out there
16:56	AimHere	At least as a reference
16:56	Foxboron	looked at it, but its not really fit when you dont know what you are looking for
16:57	AimHere	Well perhaps, though I do recall clicking on likely looking functions to see what's out there at times
17:24	jodaro	i wish i was conjing
17:26	Foxboron	(#(loop [x 0 lis %] (when (= (peek lis) nil) (x))(recur (pop lis) (inc x))) '(1 2 3 3 3 4))
17:26	Foxboron	am i on the right track now <.<?
17:26	Foxboron	For those who didnt see the chat above: Trying to count items in a list without using count.
17:28	znDuff	Foxboron: that's quite a lot more involved than what you need.
17:29	Foxboron	i honestly don't doubt that.
17:29	znDuff	but that said, it's very much on the right track.
17:29	Foxboron	any hints on whats wrong?
17:29	Foxboron	i find it rather hard figureing out the error messages in Clojure. Kinda anoying
17:30	TimMc	Foxboron: (x) calls x as a function with no args.
17:30	Foxboron	i want x as a variable, trying to search around examples doing that
17:30	TimMc	so you should gets some "expected an IFn" msg.
17:30	TimMc	Foxboron: You want the value x?
17:30	Foxboron	java.lang.ClassCastException: java.lang.Integer cannot be cast to clojure.lang.IPersistentStack (NO_SOURCE_FILE:0)
17:30	TimMc	Just write x.
17:31	TimMc	Foxboron: You have your recur in the wrong order, then.
17:31	Foxboron	TimMc, i want x as a variable for counting. Basically x = 0
17:32	Foxboron	its funny, its like trying to learn programming all over again :P
17:32	raek	Foxboron: the predicate for checking whether a seq is empty is 'empty?'. peek looks at an element in the list.
17:32	Foxboron	oh, i didnt know that actually
17:33	raek	Foxboron: the general method you are using is right. but as TimMc said you have the arguments reversed in the recur form
17:33	raek	loop has x and list, but recur has list and x
17:33	TimMc	Foxboron: I don't think you read what I wrote: (x) calls x as a fn. Note the parens.
17:33	raek	,(empty? [])
17:33	clojurebot	true
17:33	raek	,(empty? [1 2 3])
17:33	clojurebot	false
17:33	Foxboron	hah, even a repl bot here.
17:33	raek	,(rest [1 2 3])
17:33	clojurebot	(2 3)
17:34	Foxboron	raek, i got a repl setup here too :)
17:34	Foxboron	TimMc, then i asked how i can define x as a variable inside the loop. But i never really got a hint in the right direction :P
17:34	raek	so, there's some examples of the sequence api
17:34	Foxboron	thanks raek ^^
17:35	raek	you have been using the stack api which is related
17:36	raek	for sequences peek=first and pop=rest
17:36	hiredman	,(pop ())
17:36	clojurebot	#<IllegalStateException java.lang.IllegalStateException: Can't pop empty list>
17:37	raek	you can think of sequences as "iteration" in the form of data
17:37	Foxboron	i see, does make sense
17:46	DaReaper5	Hi, what is the best/proper way to support long polling/push from a client (front end javascript) on a clojure web server backend
17:47	DaReaper5	I am having trouble finding a library or approach that will support this
17:47	DaReaper5	This is the closest I have found: https://github.com/shenfeng/async-ring-adapter
18:05	Foxboron	wohoo, did it
18:06	Netfeed	is it possible to split a keyword?
18:06	raek	Netfeed: into namespace and name parts?
18:07	DaReaper5	Does anyone know the best way to facilitate long polling on a clojure web server?
18:07	DaReaper5	Should I use threads and listeners
18:07	Sgeo	What's the best way to store a chunk of binary data?
18:07	Netfeed	just the parts, (name :foo/bar) returns "bar", and i'd like the :foo too
18:07	Sgeo	A vector of bytes?
18:07	mattmoss	,(namespace :foo/bar)
18:07	clojurebot	"foo"
18:08	Netfeed	thanks
18:08	Sgeo	Uh.
18:09	Sgeo	I'm playing with byte on Try Clojure
18:09	Apage43	Sgeo: depends where it comes from and where you're gonna put it
18:09	Sgeo	Why are they signed?
18:09	Apage43	all java primitive number types except char are signed
18:09	Sgeo	That's... uh... brillant
18:09	raek	Sgeo: that's the way they are printed by default
18:10	Sgeo	And read too, apparently
18:10	Sgeo	,(byte 0xFF)
18:10	clojurebot	#<IllegalArgumentException java.lang.IllegalArgumentException: Value out of range for byte: 255>
18:10	Sgeo	,(byte 0x7F)
18:10	clojurebot	127
18:10	Sgeo	,(byte -0x7F)
18:10	Apage43	yep, can't do that.
18:10	clojurebot	-127
18:11	Sgeo	,(char 0xFF)
18:11	clojurebot	\ÿ
18:11	Sgeo	,(char 0x100)
18:11	clojurebot	\Ā
18:11	flying_rhino	hello folks
18:11	raek	the JVM does not have separate types for signed and unsigned primitives
18:11	Sgeo	Are chars unicode codepoints, at least? A little bit of sanity in the Java prims?
18:11	raek	yes, char != byte
18:11	flying_rhino	does anyone have a list of all immutable types available to me in clojure?
18:11	raek	byte is int8_t and char uint16_t
18:11	flying_rhino	all data types i mean
18:12	Apage43	Sgeo: not.. really. char is really a unsigned 16 bit number, which can't cover all of unicode
18:12	Sgeo	raek, uh, 16 bits is not enough to represent all unicode codepoints.
18:12	flying_rhino	there's vector, hash table, linked list, what else is there?
18:12	raek	Sgeo: the JVM uses UCS2
18:12	Sgeo	Can Java strings handle codepoints outside the BMP?
18:12	Apage43	java's internal string representation is UCS-2
18:12	Sgeo	I... uh
18:13	raek	so code points in the astral planes are represented using two JVM chars
18:13	Apage43	Sgeo: yep, they're just more than one "char" long, awkwardly
18:13	Sgeo	Wouldn't that be UTF-16 not UCS-2?
18:13	Apage43	JVM predates UTF-16. It's "close enough" most of the time though.
18:13	DaReaper5	oh man still having an issue here with finding a solution to facilitating long polling on clojure
18:14	DaReaper5	should i use "add-watch" in conjuction with a thread?
18:14	amalloy	DaReaper5: i suspect you would get better answers if you told someone what "long polling" is
18:14	raek	Sgeo: sorry. yes I got that wrong. it uses UTF-16
18:14	flying_rhino	what are immutable types (besides vector hash table and linked list) that are available to me in clojure?
18:14	raek	surrogate pairs and all that kind of jazz
18:15	DaReaper5	amalloy long polling is way of facilitating a PUSH to a client from a server
18:15	raek	flying_rhino: sets and queues
18:15	raek	and records
18:15	amalloy	and numbers!
18:15	amalloy	and strings!
18:15	DaReaper5	basically (from what i understand) it is just a request that does not respond until the event
18:15	raek	mutable numbers - now that's a terrible idea!
18:15	flying_rhino	what do queues and records do?
18:15	DaReaper5	i want to know a good way of waiting for an event and then responding
18:16	mattmoss	(def 3 4)
18:16	mattmoss	add-watch
18:16	mattmoss	?
18:16	DaReaper5	so this "could" be summed up (if there is no lib for it) as: "How to I do listeners in clojure"
18:16	raek	flying_rhino: you add elements to one end of the queue and take elements away at the other end
18:16	DaReaper5	mattmoss but i can't find any good examples of it
18:16	DaReaper5	:s
18:16	flying_rhino	I see
18:16	raek	records could be seen as "optimized" hash maps
18:17	raek	that can also implement protocols
18:17	mattmoss	DaReaper5: Sorry... I don't know the mechanics of long polling to be ableto suggest how to set something up.
18:17	DaReaper5	mattmoss: basically this: i need to wait until something is triggered or happens
18:18	DaReaper5	i know how to do the whole response part
18:18	DaReaper5	but how to actually wait for the event in the same thread?!
18:18	mattmoss	Why same thread?
18:18	raek	Sgeo: since you are entering encoding problem territory, beware of the java methods that convert between bytes and chars without an explicit encoding (and remember to always provide one explicitly)
18:18	flying_rhino	raek: thanks. Is it possible to build your own datatypes in clojure (say quad trees) or do you have to do it from java?
18:19	flying_rhino	raek: I know how to do it in Java, but have no idea how to do it in immutable language
18:19	raek	flying_rhino: I think you should be able to do that using defprotocol and deftype (and possibly defrecord)
18:19	DaReaper5	Its what i need for long polling, basically clojure will reseave the message then wait until something happens to send a responds
18:19	mattmoss	If same thread... then maybe a future... then block on it with deref and a timeout?
18:19	DaReaper5	response*
18:19	DaReaper5	http://stackoverflow.com/questions/6954347/how-to-implement-the-observer-design-pattern-in-a-pure-functional-way
18:20	DaReaper5	^ has the best example i have found on add-watch
18:20	DaReaper5	but (possible because of my lack of knowledge of clojure) how would i get the response to be in the same thread. Would i do this:
18:20	raek	flying_rhino: you'll probably find the datastructure implementations of ClojureScript more interesting than those of Clojure. cljs relies much more on protocols
18:21	DaReaper5	I think i should do this:
18:21	DaReaper5	(Thread/sleep 100) then check for event then (Thread/sleep 100) etc
18:21	DaReaper5	however that is horrible
18:21	flying_rhino	raek: clojurescript is that something like scripting lang fro clojure or what?
18:21	flying_rhino	*for
18:21	raek	flying_rhino: maybe this is a good example: https://github.com/clojure/data.finger-tree
18:22	raek	flying_rhino: it's a variant of clojure that compiles to javascript
18:22	flying_rhino	raek: nah I like execution speed and js isn't very fast
18:22	DaReaper5	I should just listen for an event then respond in the same thread
18:23	raek	flying_rhino: it's interesting in that it relies more heavily on protocols than on host interop (clojure has lots of stuff written in java)
18:23	flying_rhino	raek: obviously
18:24	mattmoss	DaReaper5: Why same thread? And same as what... the thread kicking things off, the thread sending the event... ?
18:24	raek	so in Clojure you have java interfaces for most datatype abstractions but in ClojureScript these are "pure" clojure abstractions
18:24	DaReaper5	thread initiating the listener
18:25	flying_rhino	raek: I see
18:25	DaReaper5	mattmoss i cant think of any other way where i would respond to a long polling event
18:25	raek	so, the clojuresctipt data structures may be a little more ideomatic since they are more recent
18:25	DaReaper5	again long polling is when i do a request to a server and just wait and wait for the event
18:25	raek	well, the overall structuring of them
18:25	flying_rhino	raek: I see
18:25	DaReaper5	as the response
18:26	mattmoss	DaReaper5: So put it in a future, then deref it. It will block... or add a timeout so you can periodically do some other task and deref again.
18:26	DaReaper5	hmm i guess this is where my lack of clojure knowledge shows
18:27	flying_rhino	raek: tbh biggest problem I have with clojure is it's singular insistence on fuctional programming. Focus on it is okay, but somethimes you need/want some mutable types.
18:28	TimMc	flying_rhino: Feel free to use transients, or even arrays.
18:28	flying_rhino	arrays? You mean like java array?
18:28	raek	sure
18:29	flying_rhino	I didn't expect clojure to have those
18:29	raek	well, you can use java arrays directly from clojure
18:30	TimMc	This ain't Haskell.
18:30	raek	but you lose the benefits of functional programming, etc
18:30	TimMc	Well...
18:30	raek	equational reasoning, thread safety, structural sharing...
18:30	flying_rhino	can I also use all other mutable types from java? (not saying that's a good thing, just asking if it is possible)
18:30	TimMc	one could certainly make an argument about whether functional programming is really about immutable data types.
18:31	raek	(if you start using uncontrolled mutation in your code)
18:31	TimMc	flying_rhino: ##(java.util.ArrayList [1 2 3])
18:31	lazybot	java.lang.ClassCastException: java.lang.Class cannot be cast to clojure.lang.IFn
18:31	TimMc	&(java.util.ArrayList. [1 2 3])
18:31	lazybot	⇒ #<ArrayList [1, 2, 3]>
18:31	TimMc	Go nuts.
18:32	raek	to me referential transparancy is one of the most important characteristics of FP
18:32	TimMc	That is certainly a pretty nice one.
18:32	DaReaper5	mattmoss thanks man, promise and future seem to be the way to go
18:32	flying_rhino	can I also use all other mutable types, like numbers and stuff?
18:32	flying_rhino	not saying ti is a good idea
18:32	TimMc	numbers aren't mutable!
18:33	mattmoss	DaReaper5: Enjoy.
18:33	TimMc	well, AtomicInteger is, I guess
18:33	raek	but what "FP" really means is disputed, of course...
18:33	flying_rhino	I mean from java
18:33	metellus	Integers are mutable, I think
18:33	TimMc	No way.
18:33	raek	flying_rhino: the variable is mutable, not the number in it
18:33	flying_rhino	I mean can I use plain java datatypes which are mostly mutable, if I am not mistaken?
18:34	flying_rhino	you mentioned array
18:34	TimMc	flying_rhino: Nothing is stopping you.
18:34	flying_rhino	good to hear
18:34	flying_rhino	look I am going to try functional way first, ofcourse but I want to know that there is ejection seat
18:35	flying_rhino	in case functional doesn't cut it.
18:35	raek	Clojure certainly has its ejection seat... :)
18:35	mattmoss	Is it a functional ejection seat?
18:35	TimMc	&(let [q (java.util.concurrent.LinkedBlockingQueue. '[a b c])] (.poll q) (.size q))
18:35	lazybot	java.lang.SecurityException: You tripped the alarm! clojail.testers.ClojailWrapper@68b653 is bad!
18:35	TimMc	lazybot: ?
18:36	brainproxy	mattmoss: yes, it will give you happy functional ejection time
18:36	DaReaper5	mattmoss: i just want to summarize promise and future... so i can be sure i understand them: Promise-> def creates a promise which is an object that can be passed to any thread. If a thread treis to deref the promise object it blocks until it is ready. When you deliver a promise it becomes available to the other threads.
18:37	TimMc	&(let [l (java.util.concurrent.atomic.AtomicLong. 5)] (.incrementAndGet l))
18:37	lazybot	⇒ 6
18:37	mattmoss	DaReaper5: That... sounds right. Also note that you can only deliver once to a particular promise.
18:37	DaReaper5	Future: like promise but you define the function that calculates the object which pritty much does a deliver at the end of the calculation.
18:38	DaReaper5	mattmoss makes sence concurrance wise
18:38	DaReaper5	This is what I am learning it from (thank god for stackoverflow) http://stackoverflow.com/questions/4623536/how-do-clojure-futures-and-promises-differ
18:39	TimMc	promise/deliver is far more powerful and flexible
18:39	DaReaper5	timmc seems like it because you get to decide when the object is available
18:39	TimMc	and where
18:39	TimMc	or even whether
18:40	DaReaper5	now i get the super complicated task of how to assign and delegate these promises
18:40	DaReaper5	basically i want a certain method call to deliver a promise to a user session.
18:41	mattmoss	DaReaper5: MAke sure to read the answer by dimagog right below the first large answer.
18:41	raek	I think you could describe 'future' as a function that returns a promise-like thing and starts a thread that evaluates an expression and deliver its value
18:42	DaReaper5	raek ya i think thats what i was trying to say
18:43	TimMc	I guess you could easily implement future using promise/deliver... but it's a actually a thing from Java-land.
18:44	alexyk	what's #_(…) as a way to comment out things?
18:44	amalloy	a way to comment out things, man. there's no other way to say it
18:44	alexyk	what's #_ ? in relation to lambdas etc
18:44	raek	alexyk: unrelated
18:44	mattmoss	It's a reader thing?
18:44	raek	#_ means "ignore the next form"
18:44	alexyk	so random syntax?
18:45	TimMc	Basically java.util.concurrent.Future + some interfaces.
18:45	raek	yes, it's done by the reader
18:45	alexyk	ok
18:45	raek	most often the first character after the # determines the "special meaning"
18:45	TimMc	,[1 #_ #_ 2 3 4 5 6]
18:45	clojurebot	[1 4 5 6]
18:46	raek	huh, they stack? :)
18:46	TimMc	and interact badly with fn literal args
18:47	TimMc	,(#(#_ %1) 'hello)
18:47	clojurebot	()
18:47	mattmoss	,#'#_
18:47	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
18:47	mattmoss	,#_#'
18:47	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
18:47	TimMc	mattmoss: It's not a var.
18:47	Sgeo	,#_#' (do)
18:47	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
18:47	mattmoss	,#_#'_
18:47	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
18:48	Sgeo	Aww
18:48	raek	alexyk: the "#" as no meaning by itself is what I was trying to say...
18:48	Sgeo	,
18:48	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
18:48	Sgeo	,#'do ; do is not a var
18:48	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve var: do in this context, compiling:(NO_SOURCE_PATH:0)>
18:48	ivan	too many #_ will overflow your stack
18:48	mattmoss	,#_o--o
18:48	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
18:48	alexyk	so #(+ % 1) is also a reader thing, with spec. meaning provided by ( ?
18:48	Sgeo	,[#'-> #'+ ; but macros and functions are]
18:48	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
18:48	Sgeo	,#_o--o (do)
18:48	clojurebot	nil
18:49	TimMc	This look slike a good time to head home.
18:49	Sgeo	,[#'-> #'+] ; but macros and functions are
18:49	clojurebot	[#'clojure.core/-> #'clojure.core/+]
18:49	mattmoss	lol
18:49	alexyk	TimMc: you must be on the wrong coast
18:49	raek	alexyk: yes, #(foo %) is just a reader shorthand that means the same thing as:
18:49	TimMc	No, I'm on the right(-most) coast.
18:49	raek	,'#(foo %)
18:49	clojurebot	(fn* [p1__325#] (foo p1__325#))
18:50	mattmoss	,`'
18:50	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
18:50	alexyk	TimMc: which is the wrong one, w.r.t. startups
18:50	raek	so "#(" means "start of anonymous function shorthand"
18:50	Sgeo	,(#(inc (#(inc %))) 5)
18:50	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.IllegalStateException: Nested #()s are not allowed>
18:51	raek	you could also think of # as switching some kind of "mode" in the reader
18:51	mattmoss	,`':'
18:51	clojurebot	(quote :')
18:51	amalloy	Sgeo: 'do is not a var, but i had a good laugh when i saw one of the monad libraries had (:refer-clojure :exclude [do])
18:52	mattmoss	,'':-
18:52	clojurebot	(quote :-)
18:52	mattmoss	quote smiley
18:53	amalloy	,'(tophat :-)
18:53	clojurebot	(tophat :-)
18:57	DaReaper5	How would I go about having a reusable/assignable promise. Here is the issue: i want to call upon the promise to retrieve the most recent event which will be stored in the promise.
18:57	DaReaper5	Actually, could i just use a blocking queue
18:57	DaReaper5	that would return the top item or block until there is one?
18:58	raek	yes, BlockingQueues can do that
18:58	DaReaper5	http://clojuredocs.org/clojure_core/1.2.0/clojure.core/seque ?
18:59	raek	http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/BlockingQueue.html
18:59	raek	and
18:59	raek	http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/LinkedBlockingQueue.html
19:00	DaReaper5	hmmm so use the java blocking queue eh
19:00	raek	blocking queues and persistent queues of promises feels like two ways of thinking about the same thing
19:00	flying_rhino	do I have threads in clojure?
19:01	flying_rhino	(I know there are better ways, I just want to know if it is available)
19:01	raek	http://clj-me.cgrand.net/2010/04/02/pipe-dreams-are-not-necessarily-made-of-promises/
19:01	raek	flying_rhino: of course!
19:01	raek	http://clj-me.cgrand.net/2009/11/18/are-pipe-dreams-made-of-promises/
19:01	flying_rhino	coz there are places where I might want to use some mutability and threads for some stuff (not a lot of stuff ofcourse)
19:02	raek	(let [t (Thread. (fn [] ...some code...))] (.start t))
19:02	raek	flying_rhino: you could also use Clojure's thread safe mutation primitives (refs, atoms, etc)... :)
19:03	flying_rhino	good to know
19:03	raek	(future ...some code...)
19:04	DaReaper5	ok ill fiure out the usage late but i think i can do a hash map of blocking queue which the long polling method request/take from.
19:04	DaReaper5	later*
19:04	DaReaper5	queues*
19:04	raek	flying_rhino: some Clojure features assume that certain expression don't have side-effects, though. this is usually clear from the documentation.
19:04	flying_rhino	I know
19:05	flying_rhino	basically strict functional programming is a little too hardcore for me.
19:38	ChongLi	flying_rhino: you ought to watch SICP
19:38	ChongLi	it'll change your perspective
19:38	flying_rhino	why?
19:38	clojurebot	why is the ram gone is <reply>I blame UTF-16. http://www.tumblr.com/tagged/but-why-is-the-ram-gone
19:39	ChongLi	then you'll start looking at imperative programming as this scary, weird thing
19:39	amalloy	watch it? read it
19:39	flying_rhino	links?
19:39	ChongLi	amalloy: the lectures are essential IMO
19:39	amalloy	i mean, i haven't watched it, so maybe the recording is really great. but i imagine you want the book as well
19:39	amalloy	$google sicp
19:39	lazybot	[Welcome to the SICP Web Site] http://mitpress.mit.edu/sicp/
19:40	amalloy	$google sicp lectures
19:40	lazybot	[Structure and Interpretation of Computer Programs, Video Lectures] http://groups.csail.mit.edu/mac/classes/6.001/abelson-sussman-lectures/
19:40	ChongLi	http://www.youtube.com/course?list=ECE18841CABEA24090\
19:40	ChongLi	err
19:40	flying_rhino	thanks
19:40	ChongLi	http://www.youtube.com/course?list=ECE18841CABEA24090
19:42	ChongLi	I especially enjoy the lecture where Gerald Sussman dresses up and writes the evaluator on the black boards
19:42	ChongLi	it has a very sentimental quality to it
19:43	flying_rhino	althought, ChongLi , I am not sure that my ambivalence is entirely due to paranoia. I am planning (for now just planning) to develop RTS game in clojure. Still not sure that it is a good idea. Basicaly games have a lot of changing state so immutability scares me somewhat.
19:43	ChongLi	the two of them are brilliant lecturers
19:43	ChongLi	just package your state in one of clojure's reference types
19:44	ChongLi	and then write a bunch of pure functions on different parts of the game logic
19:45	flying_rhino	althought real time strategies appear real time they are in fact turn based but turn expires quickly. I plan to have turn last 0.25 .
19:45	flying_rhino	So I generate new state every 0.25 seconds.
19:45	ChongLi	you might even consider using streams (lazy seqs in clojure) to represent the game as a series of instants in time
19:46	flying_rhino	basically different subsistems in game have to assemble new state every 0.25 seconds
19:46	ChongLi	every real-time game works like that AFAIK
19:46	ChongLi	I'm not aware of any continuous time games
19:46	ChongLi	SICP will teach you a different way of looking at a problem
19:47	ChongLi	not as decomposing something into a tree of specialized parts
19:47	ChongLi	but as a stack of successive layers of abstraction
19:47	flying_rhino	I dunno but what I want is easier to do than say shotter that has new state every 0.03 sec or some such.
19:52	ChongLi	flying_rhino: may I ask why you chose clojure for writing a game?
19:54	flying_rhino	I like lisp because I like macros as abstraction tools and code as data thingy is intriguing (and makes sense to me). I like Java as a platform (althought I havent done any Java programming in ages). Lisp + JVM seems like nice combo.
19:55	flying_rhino	I also want to see if it is acheivable (I mean game in lisp)
19:55	ChongLi	I see no reason why not
19:55	ChongLi	it all depends on what sort of performance demands you have
19:55	flying_rhino	performance IS concern
19:56	ChongLi	if you use lwjgl you can shift most of the burden onto the GPU
19:58	flying_rhino	I'll go with client server architecture with clojure as server (if I pick clojure). There is panda3d graphic engine at client side.
19:59	flying_rhino	panda3d is engine written in c++ and has nice python interface. I'll probably make very thin client in python. Almost all calculations will happen on server.
19:59	flying_rhino	so I don't have to worry about graphic card and stuff.
20:00	flying_rhino	I hope clojure has decent performance with multicore (that's kind of a point of immutability, right?)
20:01	flying_rhino	well at least that's a plan
20:01	flying_rhino	*the plan
20:02	flying_rhino	any objections to the plan?
20:04	flying_rhino	I'll take look at SICP, by the way
20:04	flying_rhino	thanks
20:06	ChongLi	hey
20:06	ChongLi	why python?
20:07	ChongLi	I think you're likely to get better performance out of clojure than python (unless you're calling only C libs from python)
20:08	flying_rhino	because panda3d only has python interface. And it won't do anything other than read stuff server send and tell panda3d to draw it. Server will do almost all the work.
20:08	flying_rhino	I might choose different 3d engine but panda3d is very easy to use.
20:08	ChongLi	ah
20:09	flying_rhino	I doubt python will turn out to be a bottleneck here
20:09	flying_rhino	but you never know
20:10	flying_rhino	but if you know engine with java bindings, let me know.
20:11	ChongLi	well there's lwjgl (which is what minecraft was written for)
20:11	flying_rhino	will take a look
20:11	flying_rhino	ultimately graphic is lesser concern
20:11	ChongLi	but it's mostly a raw library for doing opengl and input
20:11	flying_rhino	at first it will be 2d anyway
20:12	flying_rhino	3d isn't integral to anything
20:12	ChongLi	opengl is still good for 2D drawing
20:14	flying_rhino	well I first I'll proabably stick to java native drawing tools, provided those don't completely suck.
20:14	flying_rhino	*at first
20:16	Sgeo	JNA's Pointer docs has this
20:16	Sgeo	"Create from native pointer. Don't use this unless you know what you're doing."
20:16	Sgeo	For the Pointer constructor
20:17	Sgeo	But then in that case, if a JNAerated function takes a pointer, how do I pass one to it?
20:17	flying_rhino	ChongLi: anyway thanks for your advice
20:18	ChongLi	flying_rhino: no problem
20:18	ChongLi	I think a lot of people are rediscovering SICP these days
20:18	ChongLi	since a few articles about it have been posted on reddit/HN
20:38	yedi	so i'm still tryna wrap my mind around functional programming
20:39	ChongLi	need some help?
20:39	yedi	how would I print every other element in a list if I was looping through it with doseq?
20:39	yedi	i could use let to bind a variable and just increment it
20:39	yedi	but it seems like the imperative way to go about it
20:39	ChongLi	yeah
20:39	amalloy	&(take-nth 2 (range 10))
20:39	lazybot	⇒ (0 2 4 6 8)
20:40	ChongLi	amalloy has the right idea
20:40	ChongLi	seqs are meant for stream processing
20:40	Sgeo	,(doc take-nth)
20:40	clojurebot	"([n coll]); Returns a lazy seq of every nth item in coll."
20:40	yedi	take-nth seems like itll be handy
20:40	amalloy	the idea, as usual, is not to think about doing it "in doseq", but instead think of a way to transform the data non-mutably and then as a last step throw that into a doseq if for some reason you need to
20:40	Sgeo	That's a weird name for that idea.
20:41	ChongLi	Sgeo: what is?
20:41	Sgeo	take-nth. It's ... hmm
20:42	yedi	thanks guys
20:42	yedi	amalloy: that's a good way to think about it
20:42	ChongLi	yedi: stream processing is all about composing producers (such as range) with maps, filters and accumulators
20:42	wingy_	FP is so sweet
20:43	ChongLi	the topic is covered quite well in SICP
20:45	yedi	if only I realized how interesting/seemingly intelligent FP was when I was doing my first programming class which used scheme
20:46	ChongLi	it can be a lot to take in
20:47	yedi	for mac users: nrepl in emacs uses ctrl-up and ctrl-down to go through the repl history, but mac uses that key combination to do os related stuff
20:47	yedi	how do you get around that
20:48	ChongLi	I use M-p M-n
20:49	ChongLi	it is really nice in that you can type a bit and use those keys to search history
20:49	ivan	I use up/down
21:00	yedi	i'm getting this error when i try to count the lines in a file: https://gist.github.com/4092610
21:02	ChongLi	sounds like the lazy IO bugaboo
21:04	Sgeo	Can we just take line-seq out into a shed and burn it?
21:04	Sgeo	Or at least slap a large warning label on it?
21:05	yedi	Sgeo: what would a better alternative be for reading lines in from a file?
21:05	Sgeo	yedi, something that isn't lazy
21:05	Sgeo	Erm, I mean, hi.
21:06	ivan	something that closes the file when you reach the end and otherwise leaks
21:06	ivan	just set your fd limit really high ;)
21:06	yedi	fd limit?
21:06	ChongLi	file descriptors
21:07	Sgeo	yedi, what's going on is that line-seq isn't reading lines until they're requested
21:07	ivan	unlimit -n The maximum number of open file descriptors (most systems do not allow this value to be set)
21:07	yedi	right, aka lazy
21:07	Sgeo	They're not requested until count
21:07	ChongLi	and if the file is closed
21:07	ChongLi	they won't be able to be read
21:07	ChongLi	and an exception is thrown
21:09	yedi	so after parse-lines returns, the file closes?
21:09	ChongLi	same problem occurs in haskell (or any language where you're doing lazy stream processing with IO)
21:09	ChongLi	yeah
21:09	yedi	so I can't actually access any of those lines
21:09	yedi	i'd have to load them into memory?
21:09	Sgeo	After the with-open returns
21:09	ChongLi	or print your count inside with-open
21:10	Sgeo	Put a doall inside the with-open somewhere, that will load them into memory
21:10	yedi	is there a non lazy version of line-seq?
21:10	yedi	ah
21:10	Sgeo	(comp doall line-seq) should be non lazy
21:10	yedi	checking with doall does
21:11	Sgeo	(doc doall)
21:11	clojurebot	"([coll] [n coll]); When lazy sequences are produced via functions that have side effects, any effects other than those needed to produce the first element in the seq do not occur until the seq is consumed. doall can be used to force any effects. Walks through the successive nexts of the seq, retains the head and returns it, thus causing the entire seq to reside in memory at one time."
21:11	ChongLi	keep in mind though
21:11	Sgeo	Or you could do count inside with-open
21:11	ChongLi	that if your file is really big
21:11	ivan	maybe someone should write a lazy-line-slurper that works with file paths and closes/reopens fds as needed
21:11	ChongLi	you may not want it all in memory
21:12	yedi	right ChongLi
21:12	Sgeo	Someone should port the ResourceT stuff from Haskell into Clojure.
21:12	Sgeo	Well, not an exact port, that uses monads.
21:12	ChongLi	another solution might be iteratees
21:14	Sgeo	Clojure can kind of sort of fake some common monads.
21:14	Sgeo	(Idiomatically in everyday code not deliberately using monads, I mean)
21:17	gfredericks	is the IO monad impossible? does that require pervasive laziness?
21:18	gfredericks	or maybe it is just thunks that do IO...
21:19	ChongLi	I thought the real barrier to monads in clojure was the lack of return type polymorphism
21:20	ChongLi	the inability to write a function whose type is a -> m a
21:20	Sgeo	IO monad is not related to laziness
21:20	Sgeo	In Haskell or Clojure
21:23	gfredericks	Sgeo: I had the idea when I tried to think about implementing an IO monad with the motivating thought being that an IO a is a description of how to obtain an a. If I tried to imagine that as a data structure then I started thinking the data structure had to be lazy
21:23	gfredericks	but now I can't reconvince myself of it
21:24	Sgeo	Hint: There exists a data structure in both Haskell and Clojure, but one of the differences of the two is that Haskell's version of that structure is more restrictive.
21:25	Sgeo	^^being slightly obtuse
21:25	gfredericks	"a data structure"? is there a mystery data structure that you're trying to get me to identify?
21:26	Sgeo	Yes. Although I guess you might not call it a data structure.
21:26	Sgeo	But it's an item you can pass around and return from stuff.
21:26	gfredericks	undefined?
21:27	Sgeo	It exists in Clojure but not in Java. In Java there are annoying workarounds for it not existing.
21:27	gfredericks	a function? :)
21:27	Sgeo	Yes.
21:27	Sgeo	:)
21:27	gfredericks	and an IO a is essentially an () -> a?
21:28	gfredericks	er
21:28	gfredericks	I'm not sure that communicated by thought :/
21:28	gfredericks	s/by/my/
21:28	Sgeo	An IO a can be represented in a non-functionally-pure language with a zero argument function.
21:29	gfredericks	yeah that's what I was going for
21:29	Sgeo	That trick doesn't work in Haskell, since functions themselves aren't supposed to do impure stuff like I/O
21:29	gfredericks	and that's why I was having trouble communicating it :)
21:31	ChongLi	unsafePerformIO
21:32	Sgeo	I did say "supposed"
21:32	ChongLi	it's actually used in a bunch of libraries
21:32	Sgeo	But ideally those libraries expose a purely functional interface
21:32	gfredericks	what sorts?
21:33	ChongLi	it's often used as a hack
21:33	gfredericks	randomized algorithms?
21:34	ChongLi	that'd violate referential transparency
21:34	gfredericks	e.g. quicksort
21:35	ChongLi	they're more commonly used in doing some mutable stuff before freezing an immutable data structure
21:35	ChongLi	similar to clojure's transients
21:37	gfredericks	I guess the only legitimate use should be for performance?
21:37	ChongLi	nah, there's other uses
21:38	ChongLi	memoization for one
21:38	Sgeo	unamb
21:38	Sgeo	?
21:38	ChongLi	I guess that's performance related too
21:40	gfredericks	this is weird stuff.
21:40	ChongLi	conal elliott is way above my head
21:58	ForSpareParts	Is there a good way to prevent my nrepl from dying when I kill a window I created from it with Java interop stuff? Do I need to start a new thread, or...?
22:13	amalloy	don't set EXIT_ON_CLOSE on your window :P
22:13	ForSpareParts	amalloy, Ah. That would do it.
22:41	TimMc	clojurebot: hello
22:41	clojurebot	BUENOS DING DONG DIDDLY DIOS, fRaUline TimMc
22:41	TimMc	:-)
22:57	LesZedCB	hello!
23:24	mholmqvist	hi, I'm having some issues with the reader literals for records, anyone who can try to help a bit?
23:25	shachaf	I don't know anything about Clojure, but I bet you could get more people who can help you by asking your question.
23:25	shachaf	(As opposed to not asking it.)
23:27	Raynes	~anyone
23:27	clojurebot	Just a heads up, you're more likely to get some help if you ask the question you really want the answer to, instead of "does anyone ..."
23:27	mholmqvist	trying to serialize a record with a jodatime DateTime instance as one of the fields. I cannot get the reader to read the record after serializing it...
23:28	mholmqvist	the field looks like :timestamp #<DateTime 2012-11-17T04:17:43.675Z>
23:28	mholmqvist	and if I try with a map instead of a record it works fine and the value in the map is then :timestamp #=(org.joda.time.DateTime. 1353125863675)
23:29	mholmqvist	with #= instead of #<
23:30	mholmqvist	this causes an "Unreadable form" error in the record case
23:31	TimMc	Yeah, #<...> is never readable.
23:31	mholmqvist	that's what I thought...
23:31	TimMc	#=(...) is reader-eval syntax, which is enabled iff read-eval is bound to true.
23:32	TimMc	,(read-string "#=(the bot says nice try)")
23:32	clojurebot	#<RuntimeException java.lang.RuntimeException: EvalReader not allowed when read-eval is false.>
23:33	TimMc	None of this deals with reader literals, by the way.
23:34	mholmqvist	yeah right, sorry about the bad question. :)
23:35	mholmqvist	ok, so how can I serialize a record and read it on the other end? including the fields?
23:35	TimMc	Hmm, that sounds like a bug to me.
23:36	TimMc	(read-string "#clj.core.MyRecord{:a #=(+ 1 2), :b 2}") does what I'd expect, so it's not that the printer is avoiding doing something the reader can't handle...
23:40	mholmqvist	well, if I do (pr-str (into {} my-record-instance)) I get "#=(clojure.lang.PersistentArrayMap/create {:timestamp #=(org.joda.time.DateTime. 1353126954623)}"
23:41	mholmqvist	and if I just do (pr-str my-record-instance) I get " #MyRecord[#<DateTime 2012-11-17T04:38:24.877Z>]"
23:42	mholmqvist	so putting everything in a map works better, but I guess I'm doing something fundamentally wrong?
23:43	amalloy	sounds like you're on some nutso version of clojure, perhaps? records don't print like that on 1.4.0
23:43	mholmqvist	hm…only included 1.4.0
23:44	amalloy	https://www.refheap.com/paste/6782
23:44	TimMc	amalloy: They do with print-dup true on 1.3.0.
23:44	amalloy	ugh print-dup
23:44	amalloy	don't use it
23:45	amalloy	but you're right, it looks like print-dup is true for him
23:45	TimMc	https://www.refheap.com/paste/6783
23:45	mholmqvist	is print-dup deprecated?
23:46	TimMc	I was using print-dup to get a #= in my output.
23:47	TimMc	(Array-map, since I don't have Joda Time in that project.)
23:47	amalloy	mholmqvist: not as far as i know, but it's rubbish
23:47	mholmqvist	TimMc: right.
23:48	mholmqvist	amalloy: how can I do it any other way?
23:48	mholmqvist	get something like joda DateTime in the record?
23:48	amalloy	just use pr-str, without print-dup
23:48	TimMc	amalloy: You object to the use of #=, or something else about print-dup?
23:49	Sgeo	What's print-dup?
23:49	Sgeo	(doc print-dup)
23:49	clojurebot	"; When set to logical true, objects will be printed in a way that preserves their type when read in later. Defaults to false."
23:50	amalloy	#= is not my actual objection, but is inextricably bound up in it. the objection is that each java object (or deftype) that wants to be printable with print-dup has a totally isolated part of its code responsible for printing it, which outputs a non-compiler-checkable string that has implicit dependencies on the rest of the file
23:51	amalloy	what will happen (and does happen in clojure.lang) is that data structures evolve, and their print-dup implementations don't change, so that calling print-dup on an object produces a string that is basically rubbish
23:51	mholmqvist	amalloy: just noticed I was using print-dup
23:52	mholmqvist	using pr-str gives "MyRecord{:timestamp #<DateTime 2012-11-17T04:47:14.25}"
23:52	Sgeo	amalloy, write about it on clojuredocs?
23:52	mholmqvist	with the #
23:52	mholmqvist	"#MyRecord{:timestamp #<DateTime 2012-11-17T04:47:14.25}"
23:52	amalloy	feel free, bro. i don't use clojuredocs
23:52	mholmqvist	but still "Unreadable form" on the reader side...
23:54	mholmqvist	amalloy: now working!
23:56	mholmqvist	missing binding of print-dup. thanks TimMc for the refheaps!
23:56	mholmqvist	amalloy:
23:56	mholmqvist	amalloy: is it possible to do in any other way?
23:57	amalloy	of course. clojure is turing-complete; you can write your own version of printing based purely on the lambda calculus. but that's not very interesting, and why would you when you already have a six-character function (pr-str) that does exactly what you want?
23:59	Sgeo	Turing-complete does not imply being able to do anything. If you take Brainf*** and remove . you can't write to the screen.
23:59	TimMc	amalloy: It sounds like the problem is that pr-str by itself produces a #<...> form, which is unreadable.
23:59	Sgeo	(And BF would still be TC)
23:59	mholmqvist	yeah I have no problem using that function. I was just curious since you said it was rubbish. :)
23:59	amalloy	no, print-dup is rubbish
23:59	TimMc	Maybe the solution actually is reader literals and print-method.
23:59	mholmqvist	TimMc: that's my impression also
23:59	TimMc	amalloy: ...
23:59	amalloy	TimMc: no, he solved it by not binding print-dup