#clojure – 2010-11-13

2010-11-13

00:44	kumarshantanu1	hi, is it possible to attach documentation to an anonymous function?
00:44	hiredman	no
00:44	hiredman	but you could never look up the docs, so who cares
00:45	kumarshantanu1	I want to be able to...in an internal system
00:45	kumarshantanu1	anonymous predicate function, that could tell why a boolean test failed -- from the doc
00:45	hiredman	uh
00:45	kumarshantanu1	well anyway, since it is not possible...
00:46	hiredman	but you would never be able to get the doc
00:46	kumarshantanu1	hmm
00:46	hiredman	the question is almost nonsensical
00:47	hiredman	docstrings are metadata on vars, anonymous functions are not held in vars, qed
00:48	kumarshantanu1	right
01:16	gstamp	What does fn* do?
01:20	tonyl	it is an internal implementation of fn
01:21	tonyl	whenever you see that just think it is fn, they are mostly used to bootstrap basic functionality for clojure i think
01:29	Derander	What is that mouse chording text editor called?
01:30	Derander	acme
02:08	sandGorgon	is anyone aware of any clojure wrappers for lucene ?
02:25	sivajag	sandGorgon: i am not aware of one
02:25	sivajag	but thinking of writing
02:26	sivajag	u wanna join and do it?
02:36	sandGorgon	sivajag, sure... I actually took a look at the mailindex and clucy projects on github and am cranking out something. I want to index a load of XML files
04:13	kjeldahl	How do I make and use a symbol with an embedded space in it?
04:14	Raynes	&(symbol "blah blah")
04:14	sexpbot	⟹ blah blah
04:14	Raynes	As for using it...
04:15	kjeldahl	.. Incanter creates such headers by default when using read-data... :-)
04:16	kjeldahl	Eh, I think I might meant keyword...
04:16	kjeldahl	:quotedate with a space in it.
04:20	amalloy	&(keyword "1 2")
04:20	sexpbot	⟹ :1 2
04:29	kjeldahl	Ok thanks. For some reason (keyword "price"), (keyword "paper") etc works fine, but not (keyword "quote date") using Incanter. I'll keep digging.
04:30	Raynes	Why would you need spaces in keywords?
04:30	Raynes	I mean, do you have a specific reason?
04:59	kjeldahl	Raynes: Yes, the read-dataset method in Incanter uses keywords for column headers by default.
05:23	_ulises	morning all
05:57	_ulises	has anybody used suart sierra's clojure-hadoop lib in production?
05:57	_ulises	(sorry if this is a silly question)
05:57	_ulises	alternatively, do you know of any "good" way of interfacing clojure w/hadoop?
05:58	_ulises	I'm basically doing an investigation to see which are the available options and which ones are the best ones out there
05:58	_ulises	(I've done my share of googling, of course)
06:14	sandGorgon	_ulises, cascalog ?
06:15	_ulises	only read about it, how is it different from cascading for instance?
06:16	sandGorgon	_ulises, it IS cascading - just wrapped in clojurey way. I believe it is also being used in production in a couple of places, notably flightcaster
06:16	_ulises	oh! :D
06:17	_ulises	interesting, I assume this is even a higher level of abstraction from stuart sierra's clojure-hadoop?
06:20	sandGorgon	I'm not sure - if I had an opinion about it, i would say they are the same level of abstraction .. done differently. But dont take my word for it
06:20	esj	_ulises: Nathan has a good presentantation on cascalog somewhere... lemme go find it.
06:20	_ulises	hum, I just read a bit more about cascalog and it seems like it is a language for querying large data
06:20	_ulises	I think that I am more interested in running my own map/reduce jobs so perhaps I need something more low level?
06:22	esj	_ulises: perhaps this: https://github.com/clj-sys/cascading-clojure
06:23	esj	did sandGorgon mention it, I've just joined the room, and it looks like he might have ?
06:24	sandGorgon	esj, well i mentioned cascalog
06:24	_ulises	interesting
06:24	_ulises	this looks good, thank you chaps
06:54	mobile	,(reduce inc (range 5))
06:54	clojurebot	java.lang.IllegalArgumentException: Wrong number of args (2) passed to: core$inc
06:57	Raynes	&(map inc (range 5))
06:57	sexpbot	⟹ (1 2 3 4 5)
06:58	mobile	(loop [n 20] (recur (n-1))
06:58	mobile	whops
06:59	mobile	help me out raynes :) im on the ipad :)
06:59	Raynes	What do you need help with?
06:59	mobile	apparently it does work for irc
06:59	mobile	i forgot the comma
07:00	Raynes	&(loop [n 20] (recur (n-1))
07:00	sexpbot	java.lang.Exception: EOF while reading
07:00	Raynes	&(loop [n 20] (recur (n-1)))
07:00	sexpbot	java.lang.Exception: Unable to resolve symbol: n-1 in this context
07:01	mobile	(dec n)
07:01	sexpbot	⟹ -1
07:01	mobile	(inc 1)
07:01	sexpbot	⟹ 1
07:01	mobile	is that the karma guess.
07:01	Raynes	Yep.
07:03	mobile	is it supposed to be squares, or is that a missing character
07:30	_ulises	hum, where am I going wrong when I (require [clojure.contrib.json :as json]) ?
07:30	_ulises	ok, nm
07:40	bartj	is there a way to lazily generate a sorted set ?
07:41	bartj	is it? (lazy-seq (into #{} [1 2 3 4 5 6 7 8]))
07:43	cemerick	bartj: no, into is eager
07:43	cemerick	sets are by definition not lazy
07:44	Raynes	Eager to please!
07:44	bartj	hmm
07:46	bartj	lists are eager too!
07:47	cemerick	of course
07:47	cemerick	if they weren't eager, then lists would be lazy seqs :-)
08:04	bartj	cemerick, the only way seems to be to use lazy seq
08:04	cemerick	bartj: the only way to do what?
08:05	bartj	to generate a lazy sequence of unique elements of a list
08:06	raek	,(doc distinct)
08:06	clojurebot	"([coll]); Returns a lazy sequence of the elements of coll with duplicates removed"
08:07	raek	yes, lazy seq are the only things that are lazy
08:28	bartj	raek, thank you; is there anyway I can know a datastructure is lazy
08:29	bartj	raek, like lazy-seq? as we have seq?
08:50	fliebel	hrm, I just had Clojure read lines from a stream, and now I killed it and lost my history. Sad story :(
09:59	fliebel	How can I do something after the return value of a function without that thing becoming the return value?
10:01	chouser	let
10:01	Raynes	You don't.
10:01	Raynes	Why would you need to?
10:01	chouser	(let [x (rtn-value)] (something) x)
10:02	fliebel	I need to close an URLConnection, but that involves getting the stream first.
10:02	fliebel	So simply using with-open wouldn't work.
10:02	Raynes	fliebel: let would probably work in that case.
10:03	fliebel	Thanks, I will try some of that magic, but it felt a little ugly, so I thought I might ask before making something evil.
10:04	fliebel	I'm trying to do this: http://philippeadjiman.com/blog/2009/09/07/the-trick-to-write-a-fast-universal-java-url-expander/
10:06	Raynes	chouser: I've noticed you becoming more familiar with your & key lately. My heart pounds with glee each time.
10:10	Raynes	I'm considering setting it up so sexpbot emails me every time chouser finds his fingers closer to & than ,. I could claim that it's just usage statistics.
10:16	fliebel	What does it mean when I get a java.io.FileNotFoundException for an url? Something like 404?
10:59	fliebel	&(count (distinct (repeatedly 100 #(rand-int 100)))) ; can someone who knows his math tell me why this seems to average to somewhere near 63?
10:59	sexpbot	⟹ 62
11:14	esj	fliebel: this is the Bithday Paradox: http://en.wikipedia.org/wiki/Birthday_problem
11:15	esj	if you were to replace 100 with 365, and then instead of asking what is the probability of there being at least one shared birthday, asking what is the expected number of shared birthdays
11:16	fliebel	esj: Awesome :)
11:27	esj	fliebel: so, if you have N numbers, each drawn uniformly from [1,N], then the probability of there being n repeated numbers looks something like (N!/n!)(N-n)n/N^2, if I got my combinatorics straight (which is highly unlikely). Then to answer your particular question (which n is the most likely) you need to find the n that maximises this. I've forgotten how to do d/dn of a factorial, but you could plot the graph and see where
11:27	esj	tops out.
11:28	fliebel	ouch...
11:32	esj	you asked !
11:32	pauldoo	wolfram alpha will be your friend for that kind of thing
11:33	fliebel	Yea, I did :) Thanks! Now I have some reading to do...
11:33	pauldoo	the continuous version of factorial is the gamma function, so that'll help if you do decide to try and do derivatives
11:51	jarpiain	&(/ (- 1 (/ (count (distinct (repeatedly 10000 #(rand-int 10000))) 10000.0)))
11:51	sexpbot	java.lang.Exception: EOF while reading
11:52	jarpiain	&(/ (- 1 (/ (count (distinct (repeatedly 10000 #(rand-int 10000)))) 10000.0)))
11:52	sexpbot	⟹ 2.7601435274634283
11:52	jarpiain	that should approach e
11:52	kumarshantanu	jarpiain: what is '&' for?
11:53	fliebel	kumarshantanu: sexpbot
11:53	fliebel	kumarshantanu: it evals all clojure prefixed with &
11:53	esj	jarpiain: pretty close !
11:54	fliebel	$google e
11:54	sexpbot	First out of 228000000 results is: E! Online - Entertainment News, Celebrity Gossip, Celebrity News
11:54	sexpbot	http://www.eonline.com/
11:55	raek	,Math/E
11:55	clojurebot	2.718281828459045
11:56	slyrus	technomancy: should "lein swank" work without a project?
11:56	fliebel	So, from this we can draw the conclusion that Java is better than Google, but Google is better than Clojure :)
11:58	kumarshantanu	fliebel: transitively, Java is better than Clojure? (Holy Cow!!) ;-)
12:00	fliebel	No, because universe is bent in such a way that Clojure is actually better than both if you look at it from certain angles.
12:00	jarpiain	&(reduce + (for [x (range 20)] (/ (reduce * 1.0 (range 1 (inc x))))))
12:00	sexpbot	⟹ 2.7182818284590455
12:01	raek	bartj: (sorry for not responding earlier) no, there is no such function
12:02	bartj	raek, that is really ok...thanks again
12:09	pauldoo	do delays release the closure once they have been forced? (I'm interested if values in the expression now become eligeable for GC)
12:14	bmh	any vimclojure users about? I'm having a frustrating time with syntax highlighting
12:14	opqdonut	pauldoo: i see no reason why not
12:14	opqdonut	but I'm not completely sure
12:17	bartj	bmh, what is your question...not sure if I would be able to help, though
12:18	bmh	bartj: Highlighting is too eager. If I have a function called empty-vertex-list, empty and list get highlighted because the syntax file thinks that they're builtins
12:20	bartj	bmh, doesn't highlight for me
12:20	bmh	bartj: hurumph. Something must be broken in my vimrc then. Thanks.
12:32	LOPP	weird
12:32	LOPP	1 million times: (conj [1 2 3] 4) = 107 msecs
12:32	LOPP	(conj '[1 2 3] 4) = 75 msecs
12:33	LOPP	why
12:34	LOPP	and (conj '(1 2 3) 4) = 27 msecs
12:34	LOPP	and here I thought vectors were faster than lists
12:34	opqdonut	conjing to the list is lazy
12:34	LOPP	in what sense?
12:34	opqdonut	vectors are faster than lists for random access
12:35	LOPP	that much is obvious
12:35	opqdonut	lazy in the sense that it only allocates a closure
12:35	LOPP	ok
12:35	LOPP	but why is quoted vector conj faster
12:35	opqdonut	whereas conjing to a vector pretty much allocates a new vector
12:35	LOPP	than without conj
12:35	opqdonut	since they are persistent
12:35	opqdonut	i have no idea about the quote
12:36	opqdonut	what does the benchmark code look like exactly? (dotimes [i 100000] (conj [1 2 3] 4))?
12:36	LOPP	yes
12:36	opqdonut	maybe with quote the vector is only created once
12:36	LOPP	here's what I have now
12:37	LOPP	(time (dotimes [n 1000000] (first (conj [1 2 3] 4))))
12:37	LOPP	to force evaluation
12:37	hiredman	conj is not lazy
12:37	opqdonut	even for lists?
12:37	LOPP	and now I have 117 for list, 209 for quoted vector and 243 for vector
12:37	LOPP	so no change even if list was lazy
12:38	LOPP	seems to me lists are just faster than vectors in clojure, except for random access
12:39	hiredman	opqdonut: even for lists
12:39	LOPP	the main reason I use vectors is because I can't add at the end of list
12:39	hiredman	lists are a much simpler datastructure
12:39	hiredman	why is it surprising that they would be faster?
12:39	LOPP	because they are not in java
12:40	LOPP	ArrayList is much much much faster than LinkedList
12:40	LOPP	even for inserting at the start, until you have 500000+ elements, arraylist outperforms linkedlist
12:41	LOPP	that came as a surprise to me, since inserting at start is O(1) for linked list and O(n) for array list
12:42	opqdonut	that is surprising
12:43	LOPP	seems that using arrays + System.arraycopy is lightning fast
12:43	LOPP	linked list requires alocating a new node, which slows it down tremendously
12:44	samx	it's also not true
12:44	LOPP	really?
12:49	LOPP	I got my data from some detailed benchmarks some guy did
12:49	LOPP	might have been faulty though
12:50	opqdonut	if there's something I've learnt from twiddling with different languages, it's that allocation should be cheap
12:50	LOPP	sure
12:50	opqdonut	the jvm is a PITA in this respect
12:50	LOPP	but spawning tons of objects is bound to trigger more GC cycles
12:51	LOPP	noticed when testing clojure performance that results of consequtive runs would vary a lot
12:51	LOPP	probably because of GC
12:51	LOPP	GC doesn't only free up memory it also compacts memory
12:51	LOPP	which isn't that cheap
12:52	KirinDave	Well, hopefully ojdk will start pursing more modern gc strategies.
12:54	LOPP	well that's a riot
12:54	LOPP	:P
12:55	LOPP	haven't seen any strong improvements in java, just piling up new libs into JRE
12:55	LOPP	last big thing was (poorly) implemented templates
13:00	LOPP	huh.... found a guy claiming that hashset is faster than list
13:03	samx	well, there's lies, there's bigger lies, and then there's performance metrics
13:04	LOPP	to be honest I'd use sequences/lists all the time if I didn't need adding at the end so damn often
13:05	LOPP	gimme a list with pointer to the end and ability to add there and it's golden
13:09	jarpiain	&(let [que (repeatedly promise)] (dorun (map (fn [x q] (deliver (first q) x)) (range 10) (iterate next que))) (map deref (take 5 que)))
13:09	sexpbot	⟹ (0 1 2 3 4)
13:21	LOPP	is (iterate next que) needed? doesn't the map already iterate through a coll?
13:22	jarpiain	hmm, right
13:25	raek	jarpiain: looks similar to something I saw on cgrand's blog
13:26	raek	http://clj-me.cgrand.net/2009/11/18/are-pipe-dreams-made-of-promises/
13:49	amalloy	LOPP: well, with functional/immutable lists it's not really practical to add to the end
13:49	amalloy	but have you checked out chouser's finger trees?
13:58	fliebel	This is weird. I'm profiling a Clojure script that is running at 1% CPU and presumably spends most of its time doing IO, but VisualVM tells me it's spending most of its time in hashmap functions like assoc.
13:59	amalloy	fliebel: allocation counts as io, doesn't it?
14:00	fliebel	amalloy: I don't know, but I'm fetching urls. ;)
14:01	fliebel	So I was expecting to see all sorts of java.io and java.net functions, but I see none of them.
14:07	fliebel	I thought there was a function in core to reverse keys and values? Or a function to sort a map by values? I found snippets for both, but I'm sure they're at least in contrib somewhere...
14:09	raek	fliebel: the first one is in clojure.set: http://clojuredocs.org/clojure_core/clojure.set/map-invert
14:09	fliebel	thanks :) the other is only doable by sorted-map-by, I believe?
14:10	raek	regarding the second one, would it do the same thing as (sort-by val m)?
14:10	raek	what kind of data structure would you want from the second function?
14:11	fliebel	raek: except that it doesn;t return a map. But the other day someone said array maps guarantee order? so i can just do an into?
14:12	raek	well, I have understood things correctly, array map is an optimized implementation for hash map for small number of entries
14:12	raek	I don't know if you can assume things about it
14:12	raek	if you conj enough elements into it, the result will be a hash map
14:12	raek	and the ordering will vanish
14:13	fliebel	really?
14:13	raek	(class {:a 1})
14:13	raek	,(class {:a 1})
14:13	clojurebot	clojure.lang.PersistentArrayMap
14:13	raek	,(class (into {} [[:a 1]]))
14:13	clojurebot	clojure.lang.PersistentArrayMap
14:14	raek	,(class (into {} (for [i (range 100)] [i i])))
14:14	clojurebot	clojure.lang.PersistentHashMap
14:14	raek	seems so :)
14:14	fliebel	wowzers...
14:14	raek	if you want an ordered map, perhaps sorted-map-by is the best solution
14:15	raek	how will you use the map, btw?
14:17	fliebel	raek: Not all that mappish, so I think sorted is fine for now.
14:19	fliebel	raek: but sort takes a comparator, not a predicate, so just val will not work.
14:20	raek	hrm, I think you could do something like #(< (val %1) (val %2))
14:21	raek	there was something about functions and Comparator, anyway
14:31	amalloy	raek: #(max-key val %1 %2)
14:40	LOPP	amalloy why isn;'t it practical to add at end of immutable lists
14:41	amalloy	because your pointer is to the front of the list. you can't change the list it's pointing to, so you have to create a new list for it to point to. the same logic holds for every node but the last, so you end up copying the whole list
14:42	hircus	LOPP: you can use a vector instead; a Clojure vector is designed to grow at the end
14:42	hircus	,(conj '(1 2 3) 'x)
14:43	clojurebot	(x 1 2 3)
14:43	hircus	,(conj [1 2 3] 'x)
14:43	clojurebot	[1 2 3 x]
14:50	LOPP	amalloy you can say that for every Object, the reference points to the start of it
14:50	LOPP	the list object could easily have 2 references
14:50	LOPP	one to the head and one to the tail
14:50	amalloy	LOPP: yes. but you would have to modify the head element so that if you follow enough next pointers you get to the tail
14:51	LOPP	isn't that what happens now?
14:51	LOPP	if you take next enough times you get to the end of the list...
14:52	amalloy	LOPP: yes. but if you add something to the end without updating the head pointer that won't be true anymore
14:52	LOPP	I don't understand
14:54	amalloy	&(let [x '(1 2)] (identical? x (drop 1 (cons 0 x)))
14:54	sexpbot	java.lang.Exception: EOF while reading
14:54	amalloy	&(let [x '(1 2)] (identical? x (drop 1 (cons 0 x))))
14:54	sexpbot	⟹ false
14:55	amalloy	well, that's probably a terrible example
14:55	raek	the last cons cell of (1 2 3) has nil as its rest
14:55	LOPP	so what you are trying to say is that it's because you get a new list instance
14:56	raek	if you want to make the list (1 2 3 4), that cell's rest would have to change into the cell containing 3
14:56	raek	but lists are immutable, so you aren't allowed to change it
14:56	raek	*containing 4
14:56	LOPP	I'll take your word that it isn't possible because of the way persistency is achieved on lists
14:57	andreasmk2	hello guys, is there a way to use clojure as a scripting language inside my java program? currently what I see is that clojure can call java methods but not the opposite.
14:57	LOPP	you can call clojure from java just fine
14:58	andreasmk2	i mean calling clojure functions and passing arguments. do you have any urls for tutorials or documents ?
14:59	LOPP	I think you instantiate the Reader object and evaluate with that
14:59	LOPP	other people here probably know the details
15:00	raek	andreasmk2: http://en.wikibooks.org/wiki/Clojure_Programming/Tutorials_and_Tips#Invoking_Clojure_from_Java
15:00	raek	you can also fetch the var object with clojure.lang.RT
15:00	raek	and then use its invoke method
15:01	andreasmk2	raek, this is what i need. thank you raek :)
15:05	tonyl	hello
15:09	LOPP	is it possible to return an infinite sequence of prime numbers?
15:09	LOPP	using Euler's Sieve for instance(http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes)
15:09	amalloy	LOPP: i think clojure.contrib.lazy-seq has a primes function
15:09	tonyl	i think there is something in contrib for primes
15:10	dnolen	LOPP: http://clj-me.cgrand.net/index.php?s=Everybody%20loves%20the%20Sieve%20of%20Eratosthenes
15:11	dnolen	LOPP: infinite lazy version at the bottom.
15:12	LOPP	I wish I was as smart as cgrand :P
15:14	LOPP	hm enqueue?
15:14	LOPP	,(doc enqueue)
15:14	clojurebot	It's greek to me.
15:15	LOPP	oh right, he declared it
15:18	dnolen	LOPP: I feel the same way, cgrand is a Clojure zen master
15:42	LauJensen	Gents. Everybody looked at the new design for ClojureQL? Certain functions (disj!,conj!,take,sort) shadow core names, so either use (:use [clojureql :as cql]) or accept that there are shadow warnings when importing. Can I get some oppinions on wether we should rename these functions, or if these warnings are acceptable? (I say the warnings, because the functions can be made to behave the exact same was as those in core)
15:48	morphling	LauJensen: I'd prefer renamed functions
15:51	LauJensen	vote registered
15:55	fliebel	LauJensen: I'd prefer familiar names, with sum multimagic to make it work as expected.
15:55	fliebel	*some
15:55	LauJensen	yea me too, so its 2 vs 3 votes so far
15:56	fliebel	I think it might help to make it clear you can do the refer-clojure thing, to get rid of the warnings.
15:56	fliebel	I didn't know about that until recently.
15:57	fliebel	LauJensen: Which of the 2 are the pro-shadow?
15:57	LauJensen	either refer/exclude or use/as
15:57	LauJensen	fliebel: You and me, want conj/disj/sort/take etc, and ninjudd, pholdings nad morphling want insert-into, delete-from, sort-by, limit etc
15:58	fliebel	LauJensen: Is there some sort of setup fn involved which could automate the referring? (might be a bad idea nyway, just saying)
15:59	LauJensen	No, the automated solution is simply accepting the warnings when you import the lib
15:59	fliebel	right :)
16:08	pauldoo	can I make mutually recursive functions using two defn statements? (I don't care about tail call optimization)
16:09	pauldoo	I seem to run into an order of declaration type of problem.. ie the first defn body doesn't know about the not-yet-defined function
16:09	fliebel	pauldoo: oh, I'm to slow, I know this...
16:09	LauJensen	pauldoo: You can, but might run into stackoverflow problems. Use (declare y) to announce the 2nd function before defning the first
16:09	pauldoo	brilliant!,, declare it is :)
16:10	fliebel	Right, declare… I need to implement those fast hash lookups in my mind, and then touch typing.
16:10	fliebel	Can I get to the queue of an agent? I'm doing send-off to an agent, and I want to see if it can keep up with the flow or builds up a backlog.
16:11	pauldoo	can I declare a multimethod too? or does declare only work for defn and def?
16:11	amalloy	pauldoo: another option is letfn, though i use declare myself
16:11	pauldoo	letfn is local though right... like let..
16:11	amalloy	pauldoo: you can declare any var
16:11	pauldoo	hehe, so are multimethods vars?
16:12	fliebel	pauldoo: No but you keep them in vars, right?
16:12	amalloy	pauldoo: no, but neither are functions. the names you def them with are vars
16:12	pauldoo	right ok.. :)
16:13	pauldoo	I'm new to clojure, I only create multimethods using defmulti
16:13	pauldoo	haven't encountered creating multimethod values (without defmulti)
16:14	hircus	pauldoo: think of generic functions as abstract method on steroid
16:14	fliebel	Coming to think of it, there isn't just multi, is there? or let-multi ;)
16:14	pauldoo	fliebel: that'll be why I haven't encountered them perhaps..
16:15	amalloy	pauldoo: i've never tried it either, and it might not be possible, but it doesn't matter. just about every def wraps a var around a value
16:15	pauldoo	amalloy: yes, indeed
16:15	hircus	amalloy: what you're calling "var" is probably what we call an identifier. "var" in clojure is something specific
16:15	amalloy	there is a function that gets all the multifn objects associated with a defmulti
16:15	amalloy	hircus: i'm well aware. i'm talking about vars
16:15	amalloy	&(class #'first)
16:15	sexpbot	⟹ clojure.lang.Var
16:16	hircus	ah, yes
16:17	tonyl	what is the difference between a var and a symbol?
16:17	amalloy	tonyl: vars are a ref type
16:17	tonyl	it might be something obvious, but I'm fairly new to lisp
16:17	hircus	tonyl: a variable is bound to some value. a symbol is just a unique identifier
16:17	amalloy	&(deref #'first)
16:17	sexpbot	⟹ #<core$first clojure.core$first@36f7e6>
16:18	tonyl	so the var (ref) can be rebinded
16:19	tonyl	but not a symbol
16:19	hiredman	a ref is not a var
16:19	hiredman	by ref amalloy meant reference
16:19	hiredman	not (ref ...)
16:19	tonyl	ok
16:19	amalloy	right, thanks hiredman
16:19	tonyl	not clojure's ref
16:19	tonyl	thanks
16:19	hircus	a var can be rebinded with set! but that's discouraged in functional programming :)
16:20	amalloy	&(map class [#'first (ref first)])
16:20	sexpbot	⟹ (clojure.lang.Var clojure.lang.Ref)
16:20	tonyl	what about with (binding ...)
16:20	hircus	binding shadows the values bound to the variables
16:21	tonyl	ok
16:21	hircus	say you want to replace the function "first" with one that shouts out whenever it's called
16:21	hircus	(binding [first my-tracing-first] some-exp-that-uses-first)
16:21	tonyl	so it doesn't change the values and changes them back
16:21	hircus	actually, dotrace in clojure.contrib.trace does that for you
16:21	hircus	the changes happen only in the local scope
16:22	tonyl	ok
16:22	hircus	but it does break the otherwise static scoping
16:22	hircus	one sec
16:23	hircus	so let's say I bind x to 42 -- (def x 42)
16:23	tonyl	ok
16:23	hircus	and then define a function that just returns this value. (defn foo [] x)
16:24	hircus	you'd think this always returns 42, but now (binding [x 7] (foo)) => 7
16:24	hircus	but outside the binding, (foo) => 42
16:25	tonyl	thanks for the explanation
16:26	hircus	no prob :)
17:26	Zeiris_	What does Clojure/Lisp use to organize and structure code at a high level, higher than functions?
17:26	Zeiris_	I mean, Java uses objects. C has files/compilation units. Does Clojure also rely on files?
17:27	tonyl	you mean sequences
17:27	tonyl	maybe?
17:28	tonyl	or list in lisp
17:28	LauJensen	Zeiris_: primarily namespaces
17:29	gregh	java has files, too, which don't always map 1-1 with objects
17:29	gregh	and clojure stores source code in files. :)
17:29	Zeiris_	Yeah, I should've said "classes". I think those map 1-1?
17:30	gregh	you can put more than one class declaration in a java source file
17:39	dakrone	defn: ping
17:44	alpheus	Can namespaces mutually require one another?
17:55	technomancy	alpheus: there are ways to make it work, but it's almost never worth the trouble
17:57	dakrone	hey technomancy, can you delete a jar on clojars for me? I accidentaly renamed something incorrectly
17:58	technomancy	dakrone: I'll take a look. I'm not sure quite how to but I can try.
17:58	technomancy	what's the name?
17:58	dakrone	technomancy: sent pm
18:02	alpheus	technomancy: thought that was the case. Thanks.
18:02	amalloy	gregh: java quite often winds up with more than one class per source file
18:04	amalloy	but clojure's main organizational unit is, as mentioned earlier, the namespace. these do have a 1-1 correspondence with files in practice, though (i think? technomancy?) it's possible to break that rule
18:04	gregh	yes, particularly with inner classes
18:04	amalloy	gregh: yep, exactly
18:05	hiredman	clojure allows you group functions into protocols
18:07	slyrus	anyone know where the clojure dependency for clojure-contrib is specified?
18:07	stuartsierra	slyrus: in clojure-contrib/modules/parent/pom.xml
18:08	slyrus	ah, parent... thanks stuartsierra!
18:08	stuartsierra	welcome
18:09	slyrus	so why does current clojure-contrib get built with 1.3.0-SNAPSHOT not 1.3.0-alpha3-SNAPSHOT?
18:10	slyrus	(besides the obvious answer "because that's what parent/pom.xml says!")
18:11	slyrus	Or should I say: what's the rationale behind commit 6711b9e03f415d744594ce2a8faed48f9a2bc882?
18:11	slyrus	not that I have a problem with it, it just seems odd to reset the dependency here when the clojure HEAD is still on 1.3.0-alpha3
18:13	stuartsierra	I think the clojure HEAD just hasn't been updated
18:13	stuartsierra	that's probably a mistake
18:14	slyrus	ah, OK, that makes sense
18:14	slyrus	it's a bummer that that commit requires so many lines!
18:15	stuartsierra	yeah, another reason for phasing out the multi-module contrib; release versions are too hard
18:16	slyrus	oh... I didn't quite get that you were phasing it out...
18:16	slyrus	guess I won't spend to much time having my stuff try to deal with the multi-module version then.
18:17	stuartsierra	well, it will probably hang around for a while
18:17	stuartsierra	but new contrib libs are getting their own repositories
18:17	slyrus	and the old ones?
18:22	stuartsierra	dunno, don't have a plan for those yet
18:23	stuartsierra	Probably take the most popular ones and give them their own repos
18:23	stuartsierra	leave the rest in a "legacy" repo
18:28	slyrus	okey dokey
18:28	slyrus	would be nice to see it stabilize
18:32	slyrus	Ok, so when I build clojure, everything looks good (the jars) and I get a pom.xml, but when I mvn install, I get empty jars in .m2/repository
18:35	stuartsierra	yeah, mvn install in Clojure doesn't work
18:35	stuartsierra	You have to use Ant
18:36	stuartsierra	First download maven-ant-tasks.jar
18:36	stuartsierra	Then run ant -lib /path/to/maven-ant-tasks.jar ci-build
18:37	stuartsierra	Or try my branch with a proper Maven build: https://github.com/stuartsierra/clojure/tree/rebuild
18:37	stuartsierra	Actually, don't try that until we get the parent POMs into central
18:38	stuartsierra	which we will in a few more days probably.
18:42	slyrus	what's central?
18:43	slyrus	and I see your branch removes ant building support :( I was hoping that I could do ant ; mvn install and the right thing would happen. I guess not.
18:43	clojurebot	most horrible thing is http://tinyurl.com/b65o8e
18:49	stuartsierra	slyrus: I might add back a simplified build.xml
18:49	stuartsierra	for now just working on getting the Maven build to work so we can do faster releases
18:50	stuartsierra	"central" means Maven central, the default repository for the Maven / Ivy toolchain
18:52	stuartsierra	Right now, to build my branch, you first need to install the parent "pom.baseline" project locally.
19:42	quizme	(interleave [:a :b] [1 2]) gets turned into lists. How do I keep them as vectors? or should I just give in and use lists instead of vectors?
19:43	quizme	and if i pass that result into partition, i get more sequences. I kinda feel like i'm fighting an uphill battle.
19:43	tonyl	with into
19:43	jk_	(vec (interleave [:a :b] [1 2])) ?
19:44	quizme	oh
19:44	quizme	lemme try that
19:45	jk_	,(vec (interleave [:a :b] [1 2]))
19:45	clojurebot	[:a 1 :b 2]
19:45	quizme	jk_ (vec (partition 2 (vec (interleave [:a :b] [1 2]) )))
19:45	jk_	,(vec (partition 2 (vec (interleave [:a :b] [1 2]) )))
19:45	clojurebot	[(:a 1) (:b 2)]
19:46	tonyl	you dont need the double vec
19:46	tonyl	,(vec (partition 2 (interleave [:a :b] [1 2])))
19:46	clojurebot	[(:a 1) (:b 2)]
19:46	quizme	tonyl i want (:a 1) to be [:a 1]
19:47	tonyl	oh mm..
19:47	jk_	,(map vec (partition 2 (interleave [:a :b] [1 2])))
19:47	clojurebot	([:a 1] [:b 2])
19:47	MayDaniel	,(map vector [:a :b] [1 2])
19:47	clojurebot	([:a 1] [:b 2])
19:49	quizme	(vec (map vector [:a :b] [1 2]))
19:49	quizme	i think that's what i want
19:50	quizme	but again, should i just go with the flow and use lists ?
19:51	quizme	it feels like i'm saying "really, I really want a vector, not joking.... yeah and keep that one as a vector too. Oh yeah, and that one."
19:51	jk_	do you, in fact, really want a vector? does it matter? like you want to add to it at the end efficiently or something?
19:52	quizme	jk_ that's what i'm wondering...
19:52	tonyl	they are not lists but map returns a seq, lazy seq specifically
19:53	quizme	so it seems like i should just use lists unless I want specific performance guarantees...
19:57	quizme	(clojure.test/is (= [1 2] '(1 2)))
19:57	quizme	true
19:57	quizme	that's kind of interesting
20:00	_fogus_	quizme: why?
20:01	quizme	_fogus_ cuz it's ignoring the type.
20:02	_fogus_	quizme: But it's not ignoring the equality partition.
20:02	quizme	_fogus_ and vectors aren't sequences from what i heard.
20:02	quizme	"partition" ?
20:05	_fogus_	quizme: so clojure determines equality along a number of "partitions" sequential, maps, and sets
20:06	quizme	ohh
20:06	quizme	(is (= #{1 2} [1 2 ])) ; => false
20:06	_fogus_	quizme: try it
20:07	quizme	,(is (= #{1 2} [1 2 ]))
20:07	clojurebot	java.lang.Exception: Unable to resolve symbol: is in this context
20:07	quizme	,(test.clojure/is (= #{1 2} [1 2 ]))
20:07	clojurebot	java.lang.ClassNotFoundException: test.clojure
20:07	tonyl	,(= #{1 2} [1 2])
20:07	quizme	oops
20:07	clojurebot	false
20:09	_fogus_	,(= '(1 2 3) (doto (java.util.ArrayList.) (.add 1) (.add 2) (.add 3)))
20:09	clojurebot	true
20:09	_fogus_	quizme: So you can see that other things also fall into the sequential partition
20:10	quizme	_fogus_ got it, thanks.
20:11	quizme	_fogus_ haven't read your book yet. ...
20:11	_fogus_	quizme: One final thing. Be very careful how you use predicates like seq? and sequential? as they are leaky abstractions
20:12	quizme	leaky?
20:12	_fogus_	quizme: No worries. Hopefully you will one day. We devote a lot of space to this stuff. :-)
20:13	quizme	_fogus_ it's sitting on my computer, waiting for me.
20:14	_fogus_	Well in this specific case check out section 5.1 (I think -- the title is "Persistence, Sequences, and Complexity")
21:05	amalloy	&(identical? [:a] [:a])
21:05	sexpbot	⟹ false
21:05	tonyl	they are not the same object
21:07	tonyl	&(let [a [:a] b a] (identical? a b))
21:07	sexpbot	⟹ true
21:13	tonyl	"If init is supplied, it is evaluated, and the root binding of the var is set to the resulting value. If init is not supplied, the root binding of the var is unaffected"
21:13	tonyl	what does this exactly mean in special_forms?
21:13	tonyl	the evaluated value of init in the metadata is the value for the var?
21:14	amalloy	tonyl: (def x) vs (def x 1)
21:14	tonyl	oh facepalm i didn't see the init? in the args
21:16	tonyl	I see (def x) is virtually the same as (declare x)
21:36	sproust	Having soem trouble with Leiningen tonight. The latest clojure is "1.3.0-master" isn't it?
21:40	hiredman	1.3 has not been released
21:40	dysinger	yay
21:40	dysinger	oh lol I thought you just sad HAD been released
21:40	dysinger	s/sad/said
21:40	sexpbot	<dysinger> oh lol I thought you just said HAD been released
21:41	sproust	Is there a convenient way to use both Leiningen and a locally built Clojure? I find myself going back to the good old manual "create a makefile" approach way too often.
21:45	dysinger	You can build clojure and install it into your local maven repo
21:45	dysinger	It's been a long time since I've done that
21:45	chouser	I do it constantly
21:45	dysinger	:)
21:45	dysinger	^ there's your man
21:46	chouser	ant -lib /your/path/to/maven-ant-tasks-2.1.1.jar ci-build
21:46	dysinger	or just put maven-ant-tasks jar in ~/.ant/lib/
21:48	chouser	then when you refer to whatever version it built, lein will hopefully pull it from your local repo
21:49	chouser	sproust: that's all for you ^^^
21:49	sproust	Thanks Chouser.
21:49	sproust	I'm not sure I get everything, lots of Java-related lingo.
21:50	sproust	I don't havea "maven-ant-tasks" jar. Do I need one?
21:50	sproust	So far the best approach has been to make my list of jars by hand and start clojure this way.
21:50	sproust	OR, just to use Leiningen.
21:51	chouser	sproust: I can't speak to "best", I just do what I'm told.
21:51	sproust	But now I want the bleeding edge Clojure, and with the Contrib all split up, I'll have a ton of libs to specify. Thinking about writing a stupid Python script to do it for me.
21:51	sproust	Hmm, I meant "best thing that works for me without wasting a lot of time."
21:51	chouser	sproust: if you're not making changes yourself, you should be able to use an alpha release of clojure and be pretty close to the bleeding edge
21:52	chouser	making changes to clojure itself, I mean
21:52	sproust	What do I tell Leningen for its version number?
21:52	sproust	I tried 1.3.0-master, wouldn't work.
21:52	sproust	Where do I find out what the allowable version strings are?
21:52	chouser	try 1.3.0-alpha3
21:52	sproust	Thanks. That's the fish, mium. Now can you teach me how to fish for that number?
21:53	chouser	I can try
21:53	sproust	Please :-)
21:54	sproust	Sorry man, don't mean to give you a hard time :-) It's one of those nights where I finally get a few hours of life back to me so I can get back into hacking LISP and I find myself fixing how to launch my Clojure again instead of hacking code. Just a bit frazzled.
21:56	sproust	1.3.0-alpha3 works for Clojure; the Contrib libraries have changed now, have they? Do I have to specify each of them as a separate dependency in project.clj?
21:57	chouser	no, it's fine, I just don't actually know
21:57	chouser	there's got to be some list of artifacts somewhere, but I don't know where
21:58	chouser	ah, here you go: http://clojure.org/downloads
21:58	sproust	chouser: How do you use the new contrib libraries then?
21:58	sproust	I meant _you_.
21:58	chouser	um
21:59	chouser	I'm not sure I do
22:00	chouser	each one should have it's own "coordinate", name and version number
22:11	sproust	chouser: thanks.
22:31	SirNick	Is it valid to have a ref nested somewhere inside a structure of another ref? Say (ref x) where x references some hash map with refs in it or something. From the clojure refs page it seems this is not recommended or doesn't work. Is that correct?
22:33	amalloy	SirNick: well...it certainly works, but i wouldn't often recommended it
22:33	SirNick	amalloy: Why's that?
22:34	amalloy	usually the system you're modeling can be modeled just fine with only one layer of indirection, and it's easier to manage with less immutability
22:34	amalloy	er, mutability
22:36	SirNick	amalloy: Hmm I see, but what about if you wanted to make something like a mutable tree that needs atomic actions preformed on it?
22:37	amalloy	SirNick: then you definitely want only one reference-type thing involved. operate on a snapshot of the whole tree to create a new whole tree - no need to futz around with branches
22:38	SirNick	amalloy: Ah I see, makes sense. But you are saying that there is nothing about refs that would stop that from functioning correctly?
22:38	amalloy	a ref is just an object like any other: an immutable pointer to an object
22:39	SirNick	amalloy: Alright thanks, I was just confused by this statement on the refs page: "The values placed in Refs must be, or be considered, immutable!! Otherwise, Clojure can't help you."
22:39	amalloy	aha
22:39	amalloy	he means, don't put a java.util.HashMap in a ref
22:40	SirNick	Ah yea I thought that's what he might of meant but I wasn't sure. Thanks
23:25	quizme	http://pastie.org/1296341 <-- is there a more elegant way to do this?
23:28	quizme	i'm just trying to just conj onto a deeply indexed hash.
23:32	amalloy	&(update-in {:a {:b {:c 1}}} [:a :b :c] conj 10)
23:32	sexpbot	java.lang.ClassCastException: java.lang.Integer cannot be cast to clojure.lang.IPersistentCollection
23:33	amalloy	(doc conj)
23:33	clojurebot	"([coll x] [coll x & xs]); conj[oin]. Returns a new collection with the xs 'added'. (conj nil item) returns (item). The 'addition' may happen at different 'places' depending on the concrete type."
23:33	amalloy	&(update-in {:a {:b {:c [1]}}} [:a :b :c] conj 10)
23:33	sexpbot	⟹ {:a {:b {:c [1 10]}}}
23:33	amalloy	or assoc-in if you want to add elements to the list itself
23:33	amalloy	er, the hash
23:34	amalloy	&(assoc-in {:a {:b {:c {}}}} [:a :b :c] :d 1)
23:34	sexpbot	java.lang.IllegalArgumentException: Wrong number of args (4) passed to: core$assoc-in
23:34	amalloy	&(assoc-in {:a {:b {:c {}}}} [:a :b :c :d] 1)
23:34	sexpbot	⟹ {:a {:b {:c {:d 1}}}}
23:35	quizme	amaloy: thanks !
23:38	amalloy	quizme: and you don't actually have to have the whole structure to start with: ##(assoc-in nil [:a :b :c :d] 1)
23:38	sexpbot	⟹ {:a {:b {:c {:d 1}}}}