#clojure – 2011-01-26

2011-01-26

03:06	TobiasRaeder	morning
03:12	Scriptor	morning TobiasRaeder
05:28	edoloughlin	I keep getting a notice from sexpbot saying I have a new message and should 'use the mymail or mail commands without'. Excuse my ignorance, but what on Earth is this?
05:31	mrBliss`	edoloughlin: have a look at https://github.com/Raynes/sexpbot/blob/master/src/sexpbot/plugins/mail.clj
05:33	edoloughlin	mrBliss: Sorry, I've been a developer since 1992 but never used IRC for whatever reason until I started using Clojure. How do I send a command to sexpbot?
05:35	mrBliss`	edoloughlin: I think it is "/query sexpbot", but I'm not sure.
05:35	edoloughlin	Thanks
06:01	Leonidas	I have a global configuration (immutable) that I want to read from a JSON file and access in all functions. what is the best way to handle this? global variable? parameter to each function? a dynamically bound variable?
06:09	ejackson	Leonidas: I think a dynamically bound variable is the accepted answer, but not sure.
06:10	Leonidas	ejackson: I am thinking about posting it on the mailing list as it is not a technical problem but rather one of various pros and cons.
06:10	ejackson	I think if you search the IRC logs first, you'll find this discussed before
06:11	clgv	Leonidas: I made a configuration Object but also played with the thought of dynamically bound variables
06:11	ejackson	in fact, I'm almost certain of it
06:11	Leonidas	ejackson: the problem is, I don't know the proper search terms to get any useful results
06:39	AWizzArd	~seen rhickey
06:39	clojurebot	Pardon?
06:39	AWizzArd	$seen rhickey
06:39	sexpbot	rhickey was last seen quitting 2 weeks and 1 day ago.
06:43	ejackson	sexpbot: rhickey is not a quitter - how DARE YOU SIR !
06:49	clgv	lol!
07:05	Leonidas	http://paste.pocoo.org/show/327135/ why does this fail in json-read? I thought json-read returns the value when encountering an EOF?
07:08	clgv	A tricky question: when I open a repl in code that runs in the java Swing GUI thread I get an exeption that I am not allowed to use (in-ns) - does someone know why?
07:09	clgv	it's the debug-repl of George Jahad and Alex Osborne
07:09	raek	are you running a repl session in the swing thread?
07:09	raek	won't that block all gui events?
07:18	clgv	yes it will. it is a debug-repl to see why certain GUI code fails ;)
07:19	Leonidas	fun, I ran into a read-json bug
07:19	Leonidas	http://dev.clojure.org/jira/browse/CONTRIB-99
07:19	clgv	it works in general but I cant change the namespace to the surrounding ns of the macro with (in-ns)
07:25	clgv	The exceptions says: Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Can't change/establish root binding of: ns with set
07:25	raek	I though that bug had been fixed
07:25	raek	http://dev.clojure.org/jira/browse/CONTRIB-91
07:30	raek	there is a patch for it, but maybe it never got in...
08:26	Leonidas	get-votes-and-filter (fn [line] (remove (fn [[k v]] false) (get-votes line)))
08:26	Leonidas	this always fails with clojure.lang.LazySeq cannot be cast to clojure.lang.Associative. Why?
08:26	Leonidas	the remove-call should be a no-op
08:29	timvisher	hi all
08:30	AWizzArd	Hi timvisher.
08:32	timvisher	is there an easy way to write compound filters? i.e. (filter (and #(.isFile %) (complement #(.isHidden %))) ...)
08:33	timvisher	possibly even a filter that works on a #{} of predicates?
08:35	l0st3d	timvisher: as in (filter #(and (.isFile %) (not (.isHidden %))) ...) ?
08:36	timvisher	l0st3d: you know, I had a tickling feeling at the back of my skull that all I'd have to do was make the whole and a function...
08:37	timvisher	thanks!
08:37	timvisher	still new at this. :)
08:37	Leonidas	(fn [line] (remove (fn [[k v]] false) (get-votes line))) why does calling this result in a clojure.lang.LazySeq cannot be cast to clojure.lang.Associative error?
08:37	l0st3d	timvisher: me too ;)
08:38	clgv	timvisher: though a (filter-all #{ .isHidden isFile } ...) would be nice too ;)
08:38	l0st3d	timvisher: there's something called comp that will compose fns for you
08:38	clgv	s/#{ .isHidden isFile }/[.isHidden .isFile]/
08:43	raek	Leonidas: what happens if you just eval (get-votes line)?
08:44	Leonidas	raek: {"Foo" {:upvotes 0 :downvotes 1}}
08:45	Leonidas	strange things happen
08:45	raek	,(fn [] (remove (fn [[k v]] false) {"Foo" {:upvotes 0 :downvotes 1}}))
08:45	clojurebot	#<sandbox$eval628$fn__629 sandbox$eval628$fn__629@e5590e>
08:45	raek	,(remove (fn [[k v]] false) {"Foo" {:upvotes 0 :downvotes 1}})
08:45	clojurebot	(["Foo" {:upvotes 0, :downvotes 1}])
08:46	raek	I think the problem is somewhere else..
08:46	Leonidas	yeah, there is a [ ] there
08:46	Leonidas	where does the vector in the result come from?
08:47	raek	it's actually a MapEntry
08:47	raek	they implement IPersistentVector
08:47	raek	,(seq {:a 1, :b 2})
08:47	clojurebot	([:a 1] [:b 2])
08:47	Leonidas	I wanted to remove items which fail a certain perdicate from a dict, but what remove does is something... else.
08:48	Leonidas	is there a way how I can get a map out?
08:48	raek	,(let [m {:a 1, :b 2}] (into (empty m) (remove (fn [[_ v]] (odd? v)) m)))
08:48	clojurebot	{:b 2}
08:49	raek	this will also the preserve the map type (hash-map/sorted-map)
08:50	Leonidas	what is the point of this strange behaviour?
08:51	raek	what behaviour?
08:51	raek	remove operates on sequences. it automatically calls seq on its argument to get a sequence for it.
08:52	Leonidas	that mapentries get generated? I thought that when I 'remove' on a map I get a map of the same shape out
08:52	raek	it could be possible that they are the same map enties used internally in the map
08:53	raek	conj, into, disj, pop, peek are polymorphic and return a datastructure of the same kind
08:53	raek	the sequence functions are seq-in seq-out
08:54	Leonidas	ah, hmm, I see. Much I have to learn, still
08:56	raek	(seq x) for data structure -> sequence and (into (empty x) ...) for sequence -> data structure lets you use the same functions for any type
08:58	zippy314	Hi, I'm looking on thoughts on best practices in Clojure for handling inheritance. I've been reading The Joy of Clojure on prototyping and UDP, and I've implemented a few protocols/records. What I think I'd like to do is create a record/type that mixes in new methods, and can itself be inherited from. But I'm wondering if anybody have any pointers to best-practices/idiomatic ways of doing this in clojure?
09:02	ejackson	zippy314: i don't think it can be done. I tried before and ended up using macros to kludge it. However the more skilled present may know otherwise.
09:03	clgv	zippy314: afaik there is no such thing as inheritance between types or records in clojure.
09:04	zippy314	cigv: ejackson: is that because it shouldn't be done in clojure because there's a better way to accomplish the same functionality, or because it's a limitation of clojure? That's what I'm trying to figure out.
09:05	ejackson	ah, its not possible in clojure, deliberately I think.
09:06	zippy314	I'm reading in the docs this: "Concrete derivation is bad" (http://clojure.org/datatypes) and I'm trying to wrap my head around that.
09:06	zippy314	and also this "Tying polymorphism to inheritance is bad"
09:07	clgv	in general you can use a written function on every data that has the "attributes" that are need by the function
09:08	timvisher	i'm getting a weird issue when I try to run `lein test`.
09:08	clgv	you can do dispatch via multimethods
09:08	timvisher	it's saying that `to-file-name-suffix` cannot be resolved
09:08	zippy314	Yah. It looks like since you can simply define a record based on multiple protocols, that you can get the same effect just by mixing in lots of interfaces into one record.
09:08	timvisher	but `to-file-name-suffix` occurs nowhere in the code
09:09	timvisher	it used to, but I recently renamed it
09:09	zippy314	timvisher: you might need to do 'lein clean'
09:09	timvisher	zippy314: just had that idea. tried it and it didn't make a difference
09:10	raek	maybe ~ files lying around
09:10	zippy314	timvisher: also, maybe unsaved file so your search works, but on disk it's different
09:11	timvisher	Ah!
09:11	timvisher	I'm i'm an idiot as usual
09:11	timvisher	the core.clj file the error is referring to is my now _stale_ test/core.clj
09:11	timvisher	:)
09:11	timvisher	thanks as always, everyone
09:25	no_mind	which is a good tutorial for starting web development with clojure ?
09:26	dnolen	no_mind: http://mmcgrana.github.com/2010/03/clojure-web-development-ring.html
09:26	no_mind	thnxs
09:35	no_mind	when I run lein deps , it downloads clojure and clojure-contrib forr every new project. is there a way I can avoid this ?
09:36	jkdufair	I'm a longtime emacs user and have some decent exposure to clojure. I'm on windows and want to set up a production grade development env with Emacs/swank/lein. Recommendations re: native vs. cygwin?
09:36	ejackson	hmm, I thought it would pull them from your ~/.m2
09:37	ejackson	jkdufair: I did this, but was painful. I used the powershell for lein etc, and normal emacs. I think cygwin should work too, but I had COM stuff in the mix that prevented me from doing it.
09:38	jkdufair	ejackson: thx. i'm leaning toward cygwin and have had some success so far, but just a bit of weirdness with lein
09:39	ejackson	yes, that's where I spent most of my time gnashing my teeth. There is a port for the script to powershell which worked fine.
09:39	ejackson	if maven works I'd suggest you just use that
09:40	jkdufair	you prefer maven over lein?
09:40	ejackson	yeah
09:40	jkdufair	pros/cons?
09:40	ejackson	maven has plugins for a bunch of stuff that i do and integrates nicely with my CI
09:41	jkdufair	cool. thx
09:41	ejackson	the XML is a pain intially, but nothing dramatic.
09:50	shortlord	I have written 2 functions and now want to use them from another namespace. Both functions use a lookup table as an argument, this lookup table is defined in their namespace. What is the most functional way to use these 2 functions now? using both functions + the lookup tables and always passing these tables in other namespaces sounds like a bad idea. Should I make some light wrappers in the original namespaces that supply th
09:50	shortlord	e lookups automatically?
09:54	ejackson	shortlord: I dunno why passing the lookup is a bad idea. But, if you arrange your argument order correctly you could partial over the lookup tables perhaps ?
09:54	ejackson	for you wrapper that is
09:54	tonyl	can you just require the ns where your fns and lookup tables in the current ns you want to use them?
09:54	shortlord	ejackson: yep, building the wrapper is easy, the lookup table is the first argument
09:55	ejackson	well, that seems reasonable, i guess.
09:56	shortlord	tonyl, ejackson: well, my problem is this: When should I use a wrapper/closure and when should I supply all the arguments every time? I'm pretty sure that the lookup table won't change for the whole application, but just wrapping the function does not seem to be very functional/pure
09:57	shortlord	I could of course just use the functions without a wrapper, but that would mean that I'd need to pass more arguments every time that I call such a function
09:57	ejackson	I think a partially applied function is very functional indeed
09:58	tonyl	then i agree with ejackson, it seems that that would benefit you
09:59	shortlord	ejackson: so where should I put this partial function? just defn a function in the namespace that uses the original function with the same name and just a (partial lookup-table old-function)?
09:59	ejackson	yeah
09:59	shortlord	or should I put this wrapper function in the old namespace, where both lookup tables and functions are contained?
10:00	ejackson	sorry, the latter. put it in the original namespace
10:00	shortlord	ejackson: ok. Is there any standard name scheme for simple wrapper functions? like wrapped-<function-name> or something like that?
10:01	ejackson	no, I'd go with something like standard
10:01	ejackson	standard-<function>
10:01	ejackson	of default-<function>
10:01	ejackson	but there is no reason to suspect that this is in any way more than my own opinion
10:04	shortlord	ejackson: ok, thx a lot :)
10:14	shortlord	is it possible to use something like :as in the namespace definition to rename functions in a :use expr? like (:use [clojure.set :only (difference :as diff)])?
10:15	mattmitchell	anyone know a nice way to convert a hash-map with string values to keyword values?
10:15	Chousuke	I think you need another vector
10:15	Chousuke	ie. :only ([difference :as diff])
10:16	Chousuke	but I'm not sure, so check the docstring on use
10:17	Chousuke	mattmitchell: (into {} (map (fn [[k v]] [(keyword k) v]) original-map)) is probably the shortest way without any extra functions.
10:18	mattmitchell	Chousuke: excellent thanks!
10:18	Chousuke	note though that that may produce illegal keywords
10:18	Chousuke	if the strings have spaces in them for example
10:19	Chousuke	if you have string keys, it's often best to just keep them that way :)
10:20	mattmitchell	Chousuke: yes ok. the values are coming from a yaml file, so always come in as strings but will only ever be valid keywords
10:26	momos	Hello. How to check / modify classpath in clojure?I'm trying to write a cake task which uses my project dependent jar's, but my normally working code fails to import java dependencies. How to debug this?
10:28	mattmitchell	How can I make a "public" defonce or def? I'd like my other namespaces to have access to this value.
10:29	tonyl	def is public
10:29	tonyl	just either require the namespace where the binding is
10:30	tonyl	require or use whichever form fits you best
10:30	mattmitchell	tonyl: oh i see. so i can't just go into a diff namespace and call the other like (other/some-def) ?
10:31	mattmitchell	tonyl: ahh ok i got it! it's not a function :)
10:31	mattmitchell	tonyl: thanks
10:32	tonyl	yes, and it could be a function or a special case in the ns form whichever you prefer
10:32	mattmitchell	tonyl: ok i see
10:35	LauJensen	Chousuke: I prefer reduce ##(reduce #(assoc %1 (keyword (%2 0)) (%2 1)) {} {"string" 5 "str" 10})
10:35	sexpbot	⟹ {:str 10, :string 5}
10:59	symuyn	Let's say that I have a map: string keys → vectors of string keys.
11:00	symuyn	So it represents a directed network, and loops are allowed. If a vector contains a string A, the vector’s own key is connected to A.
11:00	symuyn	I want to create another map: string keys → sets of string keys, such that the sets only contain all of the string keys that are directly connected to it (but not from it)…including the key itself.
11:00	symuyn	(Eventually, I’d like to be able to calculate the keys’ distances too, but that can be later.)
11:00	symuyn	I can't think of a good way to start, though. Is there a library or simple function that can help me?
11:01	ejackson	does to-from make any sense in an looping network ?
11:01	symuyn	I believe so
11:01	symuyn	Think of recursive functions
11:01	ejackson	A -> B -> C -> A
11:02	ejackson	is C connected to or from A ?
11:02	symuyn	Oh dear, I think I typoed: "If a vector contains a string A, the vector’s own key is connected from A."
11:02	ejackson	well, both
11:02	symuyn	Hmm
11:02	symuyn	ejackson: Yes, both. Which it will always be, in a loop
11:03	hoggarth	symuyn: does this help? http://richhickey.github.com/clojure-contrib/graph-api.html
11:04	symuyn	hoggarth: Do you know the data format that the library's graphs are supposed to be in? I can't find it.
11:04	symuyn	How do you make a graph?
11:05	ejackson	symuyn: this might throw you off course, but I made a little dijstra toy algo last year. https://github.com/ejackson/dijkstra/blob/master/src/main/clojure/net/edmundjackson/astar.clj It makes graph, connects nodes etc, might be helpful. </end blowing own's trumpet>
11:06	hoggarth	:nodes ; The nodes of the graph, a collection
11:06	hoggarth	:neighbors)
11:06	hoggarth	oops
11:06	hoggarth	symuyn: (defstruct directed-graph
11:06	hoggarth	:nodes ; The nodes of the graph, a collection
11:06	hoggarth	:neighbors)
11:06	symuyn	hoggarth: I see, a struct.
11:06	symuyn	Pity it doesn't show up on the documentation.
11:06	symuyn	ejackson: I'll look at that, thanks
11:06	mec_	Is there a good way to filter for unique values while keeping the sequence in order?
11:06	ejackson	of course, cgrand has one too: http://clj-me.cgrand.net/
11:07	tonyl	mec_: has it happened to you otherwise?
11:08	chouser	(doc distinct)
11:08	clojurebot	"([coll]); Returns a lazy sequence of the elements of coll with duplicates removed"
11:08	chouser	mec_: ^^^
11:08	tonyl	but if you want unique values, maybe hash-set's or sorted-sets' would work for you
11:09	mec_	yes but they need to remain the way they are ordered, sets will change order
11:09	mec_	chouser: thanks a bunch
11:09	ejackson	distinct ! cool.
11:10	symuyn	hoggarth: Yes, this will do; I can't use the library directly, but it shows me how
11:10	symuyn	Thanks a lot
11:10	mec_	i seem to always pick the wrong synonym for what i want
11:11	chouser	mec_: note that if you walk to the end of the seq returned by distinct, you will end up with the whole (non-dup) collection in memory, even if you aren't holding the head of the seq
11:12	shortlord	there is no built-in operator that does the opposite of 'frequencies', so (map #(repeat (val %) (key %)) my-map) would be the easiest way, right?
11:12	shortlord	(+ a flatten in front of it)
11:13	mec_	chouser: that should be fine
11:14	symuyn	What is the hash code of a lazy sequence? What happens when it's used as a hash map's key?
11:16	tonyl	&(hash (range))
11:16	sexpbot	Execution Timed Out!
11:16	tonyl	mm good quesiton
11:16	tonyl	*question
11:18	symuyn	Seems kind of weird
11:19	tonyl	not necessarily it needs to know the values of the lazy-seq to make a hash of it, so the values are trying to be realized
11:19	chouser	shortlord: mapcat instead of map
11:20	symuyn	&(count (assoc {} (range) 1 (range) 2))
11:20	sexpbot	Execution Timed Out!
11:20	symuyn	So it tries to fully evaluate
11:21	tonyl	yes, that is my understanding of hashcode in java, but it's been a while
11:21	chouser	a lazy seq hashes to the same as a list or vector with the same contents, so it has to realize the whole thing
11:22	shortlord	chouser: how would mapcat help there? It is only one map that I want to transform into one seq
11:22	chouser	shortlord: then you don't need the flatten or a concat
11:25	shortlord	chouser: you mean like (mapcat repeat (vals foo) (keys foo))?
11:27	chouser	sure, or (mapcat #(repeat (val %) (key %)) foo)
11:27	shortlord	chouser: nice solution, thx
11:28	chouser	I dislike flatten, and (apply concat (map ...)) always suggests (mapcat ...)
11:30	symuyn	flatten does seem a little inefficient
11:31	chouser	well, it's a big hammer
11:31	chouser	,(mapcat #(repeat (val %) (key %)) {:a 2 :b 2 [:c :d] 3})
11:31	clojurebot	(:a :a :b :b [:c :d] [:c :d] [:c :d])
11:31	chouser	,(flatten (map #(repeat (val %) (key %)) {:a 2 :b 2 [:c :d] 3}))
11:31	clojurebot	(:a :a :b :b :c :d :c :d :c :d)
11:32	chouser	if it's actually what you want, fine, but in my experience it rarely is.
11:38	pdk	(doc xor)
11:38	clojurebot	Gabh mo leithscéal?
11:38	chouser	(doc bit-xor)
11:38	clojurebot	"([x y]); Bitwise exclusive or"
11:39	pdk	i was thinking logical xor to use alongside or/and but hey
11:40	chouser	yeah, I don't think Clojure's got that
11:40	pdk	funky
11:41	chouser	it couldn't short-circuit or do anything useful varargs like or/and
11:51	zippy314	is there a way to give defrecord a doc string so that it will show up in autodoc?
11:54	tonyl	zippy314: AFAIK there isn't
11:54	zippy314	hmmm gripe.
11:56	mec_	,(str (doall (range 10)))
11:56	clojurebot	"clojure.lang.LazySeq@9ebadac6"
11:57	chouser	zippy314: usually the public face of a defrecord is a factory function, which can of course have a docstring
11:57	chouser	,(pr-str (range 10))
11:57	clojurebot	"(0 1 2 3 4 5 6 7 8 9)"
11:57	zippy314	chouser: right!
11:58	mec_	ah that works, but what am i thinking wrong about doall?
11:59	chouser	str and pr-str do the same thing in a lot of cases. strings and lazy-seqs are a couple of the relatively few exceptions
11:59	chouser	,((juxt str pr-str) [1 2 [3 4] '(5 6)])
11:59	clojurebot	["[1 2 [3 4] (5 6)]" "[1 2 [3 4] (5 6)]"]
11:59	chouser	,((juxt str pr-str) "hi")
11:59	clojurebot	["hi" "\"hi\""]
12:00	pdk	is there a way to capture a full java stack trace say to a file
12:00	pdk	vs having it print to the command line and get cut off
12:03	zakwilson	danlarkin: that NoSQL presentation you posted last night was interesting. When put in the terms the presented used, it seems likely that I do have a single question I usually want to answer and Mongo is probably a good fit for the problem.
12:03	tonyl	maybe binding err to a reify'ed PrintWriter and change the method that outputs to write to a file
12:03	zakwilson	s/presended/presenter
12:04	tonyl	pdk: ^^ just the first thought that came to me
12:04	tonyl	so it might be wrong
12:04	zippy314	pdk: (binding [err (java.io.PrintWriter. (writer "/your/file"))]
12:05	danlarkin	zakwilson: cool, I'm glad you found some value from it, and glad you've come to an evidence-based conclusion :)
12:05	tonyl	simpler zippy314
12:05	zippy314	:pdk, then (.printStackTrace e err)
12:06	zakwilson	And if I'm lucky, scaling will be a concern.
12:06	symuyn	Another question! Pre- and post-condition are idiomatic, and that Clojure style guides says they're supposed to be ubiquitous.
12:06	symuyn	Is there any way to turn them off, though?
12:07	symuyn	(When you're not debugging, for production runs)
12:10	mattmitchell	is it possible to "use" namespace B in namespace A, then from namespace C, access the B functions "through" A?
12:12	ohpauleez	mattmitchell: Take a look at potemkin
12:13	ohpauleez	Typically, what you're asking for you wouldn't do, but potemkin allows you to man-handle the namespaces and imports
12:14	mattmitchell	ohpauleez: oh cool ok. that's exactly what i'm looking for.
12:14	ohpauleez	You would normally just use, B and A in C. I personally prefer require, or use-only so that it's clearly documented what I'm using, and where it came from.
12:14	ohpauleez	mattmitchell: awesome! Glad I could help
12:14	mattmitchell	ohpauleez: ok so another related question, is it possible to define a function in a different namespace?
12:15	ohpauleez	mattmitchell: http://clojuredocs.org/clojure_core/clojure.core/in-ns
12:16	ohpauleez	actually, with-ns is probably what you want
12:16	ohpauleez	&(doc with-ns)
12:16	sexpbot	java.lang.Exception: Unable to resolve var: with-ns in this context
12:16	ohpauleez	it's in contrib
12:17	ohpauleez	mattmitchell: http://clojuredocs.org/clojure_contrib/clojure.contrib.with-ns/with-ns
12:17	mattmitchell	ohpauleez: excellent thanks again!
12:17	ohpauleez	np, glad I could help!
12:42	momos	Perhaps a lot of you is developing in Clojure at work or for commercial projects. do you publish your code on github etc? if yes, how do you link the commercial and open-source side? under what license do you publish the code?
12:45	ejackson	momos: a good example of this is Bradford Cross's stuff. Check out https://github.com/getwoven. I guess the license is in there somewhere if you look.
12:45	momos	hmm I've seen this repo somewhere
12:47	ejackson	it used to be called clj-sys
12:48	momos	the license isn't very noticeable.... can't find it
12:48	momos	maybe there's a default one for clj :P
12:49	momos	ah.ok. there are a bunch of mit licenses just on some projects
12:51	ohpauleez	momos: I'm sure you'll see mostly EPL or MIT/BSD licenses for things
12:51	ohpauleez	you can then take those, and use them in a private, proprietary project
13:26	amalloy	pdk: if you're looking for logical xor: ##(apply not= (map boolean [:a :b]))
13:26	sexpbot	⟹ false
13:27	pdk	GASP
13:44	defn	'lo
13:47	bobo	if im handed a vector thats realy a map ie [key1 val1 key2 val2] whats the simplest way to turn it into a real map?
13:47	bobo	cant figure something simple out
13:47	mefesto	bobo: vec i think
13:48	mefesto	,(vec [:a 1 :b 2 :c 3])
13:48	clojurebot	[:a 1 :b 2 :c 3]
13:48	mefesto	oops, what am i thinking :)
13:48	bobo	:-)
13:48	mattmitchell	could someone show me how i could "dry" this up? https://gist.github.com/797191
13:48	mefesto	,(apply hash-map [:a 1 :b 2])
13:48	clojurebot	{:a 1, :b 2}
13:49	bobo	mefesto: ofcource! thanks
13:49	mattmitchell	the only differences between the 2 are the names of the database table and a mapping in "m"
13:50	chouser	mattmitchell: (db/partners (documentor m/partner))
13:50	chouser	then just write your documentor function
13:54	mattmitchell	chouser: oh right. so pass in the functions, don't immediately execute them
14:03	KirinDave	It's so cute when someone is like, "Oh dang, macros are pretty weird." for the first time.
14:03	KirinDave	e.g., http://brandonbyars.com/2008/02/12/understanding-syntactic-macros/ that is making its way around hackernews
14:06	mattmitchell	how do i get a reference to a function in another namespace and pass it off as a callback to something else?
14:07	Scorchin	Hey guys, I sent in a pull request a while back to clojure-contrib and it's not been merged. I realise it's probably because it's not considered good enough, but I'd love to know why so I don't make the same mistake again. Pull request here: https://github.com/clojure/clojure-contrib/pull/4
14:08	chouser	mattmitchell: just use its name
14:08	hiredman	Scorchin: you should read the guid for contributing on the clojure website
14:08	chouser	, clojure.core/filter
14:08	clojurebot	#<core$filter clojure.core$filter@1c0035b>
14:08	hiredman	Scorchin: clojure and clojure-contrib don't take pull requests
14:08	Scorchin	hiredman: Thanks! That makes a lot of sense
14:09	mattmitchell	chouser: oh that's embarrassing, thanks :)
14:10	nishant	how can I start swank with a bigger heap?
14:20	nishant	nevermind
14:52	pauldoo	how do I zip two sequences together? e.g. turn [[1 2 3] [4 5 6]] into [[1 4] [2 5] [3 6]]
14:52	chouser	,(map vector [[1 2 3] [4 5 6]])
14:52	amalloy	&(map vector [[1 2 3] [4 5 6]])
14:52	clojurebot	([[1 2 3]] [[4 5 6]])
14:52	sexpbot	⟹ ([[1 2 3]] [[4 5 6]])
14:52	chouser	wow
14:52	amalloy	haha
14:52	amalloy	&(apply map vector [[1 2 3] [4 5 6]])
14:52	sexpbot	⟹ ([1 4] [2 5] [3 6])
14:53	chouser	exactly the same mistake at exactly the same moment
14:53	amalloy	i was even thinking "do i need apply here? no, not for this instance, because map works on a sequence"
14:53	chouser	pauldoo: hi, btw.
14:54	amalloy	pauldoo: there's also ##(apply zipmap [[1 2 3] [4 5 6]]) if you want it as a map instead of an ordered set of pairs
14:54	sexpbot	⟹ {3 6, 2 5, 1 4}
14:54	pauldoo	aha! the vector function is useful! :)
14:54	pauldoo	cunning!
14:54	pauldoo	chouser: hello to you to. :)
14:55	semperos	incanter does something similar
14:57	__name__	sexpbot: (contains? '(1 2 3) 1)
14:57	__name__	&(contains? '(1 2 3) 1)
14:57	sexpbot	⟹ false
14:57	fogus`	pauldoo: And also ##(apply interleave [[1 2 3] [4 5 6]]) if you don't want them grouped in vectors. ;-)
14:57	sexpbot	⟹ (1 4 2 5 3 6)
14:57	__name__	why does it just randomly say false instead of failing?
14:58	pauldoo	fogus`: right-o
14:58	pauldoo	I'm twatting about reimplemting "separate" so that the filter function is only called once per element
14:58	chouser	__name__: well, it has no keys at all, so I guess it doesn't have a key of 1
14:59	pauldoo	(defn separate [f s]
14:59	pauldoo	(let [t (map vector (map f s) s)]
14:59	pauldoo	[ (map second (filter first t)), (map second (filter (complement first) t)) ]))
14:59	pauldoo	is the best I have so far
14:59	amalloy	__name__: there is nothing random, and it is not failing
15:00	amalloy	contains? is for seeing if a map contains a key, not if a list contains a value
15:00	amalloy	you want ##(doc some) for that
15:00	sexpbot	⟹ "([pred coll]); Returns the first logical true value of (pred x) for any x in coll, else nil. One common idiom is to use a set as pred, for example this will return :fred if :fred is in the sequence, otherwise nil: (some #{:fred} coll)"
15:00	__name__	amalloy: why does it work on a list then?
15:01	fogus`	__name__: This explains it well. http://en.wikibooks.org/wiki/Clojure_Programming/FAQ#Why_doesn.27t_contains.3F_do_what_I_expect_on_vectors_and_lists
15:01	amalloy	&(some #{1} '(1 2 3))
15:01	sexpbot	⟹ 1
15:01	__name__	i know that that is how it is done, but why does the compiler not tell?
15:02	amalloy	$source contains?
15:02	sexpbot	contains? is http://is.gd/60Qkhn
15:02	__name__	ah
15:02	__name__	i see
15:02	__name__	now it makes sense, thanks
15:02	amalloy	welcome
15:03	shortlord	is there some operator like for that travesers multiple bindings parallel? like (for [x [1 2 3 4] y [1 2 3 4]] [x y]) => [[1 1] [2 2] [3 3] [4 4]]
15:03	chouser	shortlord: map
15:04	chouser	,(map vector [1 2 3 4] [1 2 3 4])
15:04	clojurebot	([1 1] [2 2] [3 3] [4 4])
15:04	chouser	amalloy: where were you?
15:04	shortlord	chouser: not as easliy understandable with big expressions as functions, but I guess it has to do
15:05	amalloy	chouser: jeez sorry, i guess i have to quit my job to keep up with you
15:05	amalloy	shortlord: you can do this with for also
15:05	chouser	shortlord: I've thought about how to add that as a feature of 'for' somehow, but I haven't come up with anything that isn't clearly worse.
15:05	amalloy	or...no, maybe you can't
15:05	chouser	amalloy: well, it was the same answer as we tied on last time. I assumed I was racing you again. ;-)
15:06	shortlord	chouser: well, there are already tags like ':let', right? something like ':parallel' would be nice
15:06	amalloy	&(for [[x y] (interleave [1 2 3 4] [:a :b :c :d])] [x y])
15:06	sexpbot	java.lang.UnsupportedOperationException: nth not supported on this type: Integer
15:07	chouser	shortlord: but how would you use it that doesn't end up looking like just a 'map' inside the 'for'?
15:07	nickik	first we should get the pmap stuff write (fj) then we can start build parallel everything on top of that.
15:07	chouser	different kind of parallel
15:08	amalloy	chouser: but wouldn't it be so much fun to combine them
15:08	shortlord	chouser: what do you mean? you could just use something like [x y] inside the for, which should be quite nice in cases where you have large expressions that otherwise would have to be defined as functions previously
15:09	chouser	shortlord: do you have an example in mind of how you could use it?
15:12	shortlord	chouser: I have an application where I have a vector that holds a lot of similar maps (it's a field made up of fields with quite a few attributes). Now I am using a token that marks one field; this token is a ref that stores the vector index of the field that it references
15:12	amalloy	shortlord: i think he means, write a for statement using the syntax you wish existed
15:12	chouser	shortlord: I guess I'm talking about about the syntax than the semantics. Do you have a little code snippet of how you'd use for with :parallel?
15:13	chouser	:-)
15:15	shortlord	chouser: I'm not sure whether I understand what you want. The syntax should be as simple as that: https://gist.github.com/797350 If you want a usecase, that's what I've tried to describe
15:16	chouser	shortlord: so :parallel would group the previous binding (x in your example) with the following (y)
15:17	chouser	if you had more than two in the group, you would pu :parallel between all of them (like infix notation)?
15:17	chouser	:when and :while would be illegal inside such groups?
15:19	tonyl	that is a very big macro
15:19	tonyl	for
15:19	chouser	yes. yes it is.
15:20	shortlord	chouser: ':parallel' would be used equal to :let, so :while and :when should still be allowed. :parallel would just make the bindings after it run at the same index as the main binding in for. But yes, having several bindings in the main for block zould be a problem
15:21	amalloy	shortlord: there is no "main" binding
15:21	shortlord	amalloy: I mean the normal binding pair without any tags
15:22	mefesto	this is to avoid (map vector xs ys zs) ?
15:23	shortlord	mefesto: in case the function is a simple as vector, map is clearly a good choice. but for with such a tag could be nice for larger expressions
15:23	chouser	right. (for [[x y] (map vector [1 2 3 4 5] [1 2 3 4 5])] [x y]) would be one way to write that gist currently
15:23	mefesto	(for [[x y z] (map vector xs ys zs)] [z y x])
15:25	chouser	Maybe (for [[x y z] :parallel [xs ys zs]] ...) :-)
15:32	tonyl	if there are lager expressions, just pull them up as a function
15:37	shortlord	tonyl: yeah, I guess that should do the job well enough
15:38	shortlord	what is the recommended way to create a map for a small collection of things? array-map?
15:38	amalloy	chouser: not sure if you were serious with your last suggestion but that would mess up the binding-partitioning
15:39	tonyl	hash-map
15:39	tonyl	&(hash-map 1 2 3 4)
15:39	sexpbot	⟹ {1 2, 3 4}
15:39	__name__	why can i not add metadata to an integer?
15:39	amalloy	shortlord: probably (into {}), which will decide for you whether to use an array
15:39	amalloy	&(instance? IObj 1)
15:39	sexpbot	java.lang.Exception: Unable to resolve symbol: IObj in this context
15:40	amalloy	&(instance? clojure.lang.IObj 1)
15:40	sexpbot	⟹ false
15:40	__name__	or, rather, how can i attach it?
15:41	chouser	amalloy: yeah, I wasn't very serious
15:43	amalloy	__name__: put it on something other than an integer :P
15:44	__name__	amalloy: I guessed that.
15:44	amalloy	&(-> 10 vector (with-meta {:name "frank"}) ((juxt first meta)))
15:44	sexpbot	⟹ [10 {:name "frank"}]
15:46	shortlord	how random is clojure's shuffle? it does not seem to shuffle a seq a lot
15:47	amalloy	shortlord: as random as pseudorandom gets. it calls java.util.Collections.shuffle
15:48	amalloy	$source shuffle
15:48	sexpbot	shuffle is http://is.gd/xc6JDT
15:48	shortlord	amalloy: ok. I guess it just seems not very random at times... normal paranoia ;)
15:49	amalloy	indeed. humans are terrible at randomness
15:50	hiredman	I suggest running some stats
15:53	__name__	$source with-meta
15:53	sexpbot	with-meta is http://is.gd/D0GjxE
15:58	__name__	&(with-meta 1/1 {:k "v"})
15:58	sexpbot	java.lang.ClassCastException: java.lang.Integer cannot be cast to clojure.lang.IObj
15:58	__name__	&(with-meta 1/2 {:k "v"})
15:58	sexpbot	java.lang.ClassCastException: clojure.lang.Ratio cannot be cast to clojure.lang.IObj
16:04	robonobo	__name__, you can private message sexpbot if you want to use it's services without flooding the channel
16:04	pdk	(doc repeatedly)
16:04	clojurebot	"([f] [n f]); Takes a function of no args, presumably with side effects, and returns an infinite (or length n if supplied) lazy sequence of calls to it"
16:04	__name__	i did not flood the channel, did i?
16:04	pdk	(doc repeat)
16:04	clojurebot	"([x] [n x]); Returns a lazy (infinite!, or length n if supplied) sequence of xs."
16:04	robonobo	__name__: no, but you were of risk of doing
16:05	__name__	robonobo: why?
16:05	robonobo	just use sexpbot here if it's pqrtof dicussion
16:06	__name__	robonobo: it was, kind of.
16:06	robonobo	oh, i see, cqrry on, my apologies good sir
16:07	brehaut	robonobo: you need to get your \a key checked
16:07	semperos	perhaps he's using a French keyboard
16:08	thuner	He everyone!
16:08	thuner	I followed the instuction if https://github.com/richhickey/clojure-contrib/blob/master/README.txt, however the command "mvn package" did not created the target directory. Anyone had the same issue?
16:09	amalloy	thuner: richhickey's repository is quite out-of-date. i don't know if it will fix your specific problem but you should use the clojure/clojure-contrib repo
16:10	thuner	thank's I'll give a look at it
16:19	__name__	amalloy: is there no way to wrap an integer in something that implements IObj if one wants metadata?
16:19	amalloy	__name__: what's wrong with the vector-wrapping snippet i gave?
16:20	__name__	amalloy: that it returns [int meta] instead of the int with the meta attached?
16:21	tonyl	__name__: you could reify your own "box" I don't know how that would affect your algorithm
16:21	amalloy	&(-> 10 vector (with-meta {:name "frank"}))
16:21	sexpbot	⟹ [10]
16:21	amalloy	the ((juxt first meta)) at the end is to unwrap that into the original integer and the meta you attached to the vector
16:22	chouser	you'd have to decide what operations on the number retain which metadata
16:22	amalloy	not that this is really a great idea anyway. instead of attaching meta to an integer, why not just use a real datastructure that stores the information you need
16:27	semperos	learning ring-based web application in Clojure, using enlive and moustache
16:27	semperos	I define an enlive template (deftemplate) called "index"
16:27	semperos	deftemplate returns a lazy seq of strings
16:28	semperos	I then use ring.util.response/response to put that into the :body of a response
16:28	semperos	(response (index))
16:28	__name__	amalloy: it's more of a principle thing really.
16:28	__name__	amalloy: I just wished i could attach metadata without caring what type the data is.
16:28	semperos	on the repl, the lazy seq is evaluated, and I see what I expect
16:29	semperos	but when I run it in my web app, I just get a string representation of the lazy seq, "clojure.lang.LazySeq@dd5c324b"
16:29	brehaut	semperos: i use (defn render [s] (apply str s)) from dnolen's enlive tutorial
16:29	semperos	yeah
16:29	semperos	I nkow I can do apply str all over the place :)
16:29	semperos	but the Ring spec says it takes an ISeq
16:29	semperos	of strings
16:29	semperos	in addition to a plain string
16:29	semperos	was wondering if I was missing something obvious
16:30	semperos	about the evaluation of a deftemplate's lazy seq of strings
16:34	brehaut	semperos: ring.uril.servlet/set-body does check for seq's
16:34	brehaut	semperos: https://github.com/mmcgrana/ring/blob/master/ring-servlet/src/ring/util/servlet.clj#L79-83
16:35	semperos	right
16:35	semperos	it works at the repl, when I give the :body a seq of strings
16:36	semperos	just not in the app
16:36	brehaut	does (seq? (index ...)) return trye?
16:36	semperos	yes
16:37	semperos	in the app, the :body is actually set to "clojure.lang.LazySeq@xxxxx"
16:38	brehaut	which is what you would expect if str is called on the lazy-seq directly
16:38	brehaut	(str (lazy-seq [1 2]))
16:38	brehaut	bah
16:38	brehaut	$(str (lazy-seq [1 2]))
16:38	chouser	use & or ,
16:38	semperos	&(str (lazy-seq [1 2]))
16:38	sexpbot	⟹ "clojure.lang.LazySeq@3e2"
16:38	brehaut	thanks
16:39	semperos	yep, I get that
16:39	semperos	I'm sure I'm just missing something very basic
16:40	semperos	so (response) takes anything that is allowed by the Ring spec as part of the response :body
16:40	semperos	and sticks it in there
16:40	semperos	so at the repl, if I do (response (index)), I get everything evaluated correctly
16:40	semperos	doesn't do the same when I add it to a route with moustache
16:40	semperos	[""] {:get (fn [req] (response (index)))}
16:41	semperos	that's my confusion
16:45	LauJensen	For the Emacsers in here: http://offtopic.bestinclass.dk/post/2942525776/my-emacs-color-theme
16:46	semperos	nice
16:49	robonobo	LauJensen: your server seems to be down
16:49	LauJensen	robonobo: ?
16:49	LauJensen	robonobo: http://www.downforeveryoneorjustme.com/
16:50	neilcj	not down for me ;)
16:50	__name__	neither
16:51	neilcj	LauJensen: pretty theme, thanks for sharing
16:51	robonobo	it's back after a few tries (it was a maximum bandwith exceededthing, but with nicer layout)
16:52	pdk	did i ever mention
16:52	pdk	the parens matching in vimclojure has a really bad case of alzheimer's
16:53	brehaut	semperos: what middleware are you using (if any)
16:53	semperos	stacktrace, keyword-params, reload, and a custom one; going to try without the custom one
16:54	semperos	gah
16:55	semperos	well, that pinpoints where the error was
16:55	brehaut	:)
16:55	semperos	not surprisingly, my own mess
16:55	LauJensen	neilcj: np :)
16:56	LauJensen	pdk: Thats fair enough, since you yourself have got to have a pretty bad case of alzheimers to be using Vim in the first place
16:56	brehaut	LauJensen: theme looks nice
16:56	LauJensen	brehaut: thanks - notice how the foreground != the background. You could learn a few things :)
16:56	brehaut	LauJensen: could do with some more eye searing yellow though
16:56	LauJensen	brehaut: its got plenty yellow - I even got a complaint on twitter about it
16:56	brehaut	haha
16:56	brehaut	classic
16:56	pdk	wellllll
16:56	pdk	granted!
16:59	ohpauleez	I use wombat, and still love it: http://dengmao.wordpress.com/2007/01/22/vim-color-scheme-wombat/
17:00	ohpauleez	I made a 256 color scheme for it
17:02	LauJensen	ohpauleez: You can paint Vim... but its still Vim :(
17:03	ohpauleez	haha you're relentless LauJensen
17:03	LauJensen	Indeed :)
17:03	LauJensen	Its called Persistent
17:03	ohpauleez	paredit.vim + vimclojure + vim + zsh seems to do the trick for me
17:04	LauJensen	oh, you didn't tell me you were a beginner.. Beginners are allowed to evaluate their tools
17:05	wolverian	there's a paredit.vim? oh my.
17:05	wolverian	oh, slimv.
17:06	wolverian	I never managed to get vimclojure and slimv working together. slimv would force lisp syntax highlighting on my buffers.
17:06	chouser	experts must accept LauJensen's word without question
17:06	LauJensen	You can trust chouser, he's been here forever
17:10	ohpauleez	wolverian: I just yanked paredit.vim out of slimv
17:10	ohpauleez	haha LauJensen I just caught myself up
17:11	LauJensen	ohpauleez: So you're using Emacs now?
17:11	ohpauleez	I always HAVE used it. Clojure is the first Lisp I feel comfortable editing in vim, and do most of my day to day edits in vim. But yes, I use both
17:11	ohpauleez	there, I admitted it :)
17:12	brehaut	ohpauleez: clojure is the first lisp i have felt comfortable editign in emacs
17:12	LauJensen	:D
17:13	LauJensen	I gotta take off gents, but as always, it was fun hanging out with you :)
17:13	brehaut	gnite lau
17:13	ohpauleez	later
18:04	__name__	http://paste.pocoo.org/show/327503/
18:05	__name__	how do i prevent this from happening?
18:07	brehaut	__name__: which clojure are you using?
18:07	brehaut	__name__: 1.3?
18:07	__name__	brehaut: 1.2
18:07	__name__	oh, wait
18:07	__name__	it's 1.3
18:08	brehaut	clojure-version
18:08	brehaut	thats why
18:08	__name__	yes, i typed it into the wrong repr. i am deeply sorry.
18:08	brehaut	no problem
18:09	__name__	oh, and of course `map second`
18:10	__name__	note to self: do not code in an unfamiliar language when not well-rested, and if you do, do not annoy nice irc people.
18:12	amalloy	__name__: transitioning from common-lisp, it looks like? or maybe scheme?
18:12	__name__	amalloy: python, actually :-)
18:12	brehaut	that would explain your handle :)
18:13	__name__	amalloy: what made you think i am a schemer or clisper?
18:13	amalloy	__name__: interesting. i know python has [a b c] list literals, so i'm a bit puzzled as to why you're not using clojure's
18:13	amalloy	(list blah blah) and '(blah blah) are easily replaced by [blah blah]
18:13	__name__	amalloy: because they are vectors?
18:13	__name__	amalloy: if i am not completely mistaken it's not the same thing
18:14	amalloy	__name__: vectors are almost always better for handling data
18:14	__name__	But in this case a vector is better.
18:14	amalloy	i mean, it doesn't matter for tiny-little lists
18:14	__name__	because i am not doing any stuff that you would use linked lists for.
18:14	amalloy	but the syntax is more convenient for vectors, and it rarely matters which you use if you're not adding
18:14	__name__	Yes, that's what I meant.
18:15	amalloy	__name__: plus, vectors support fast adding to the end, while lists support fast adding to the front
18:15	amalloy	so even if you're using it as a linked list you have to choose
18:15	amalloy	chouser: now's your chance! sell us all on finger trees!
18:16	__name__	amalloy: http://paste.pocoo.org/show/327511/ is this better?
18:16	amalloy	yep
18:17	__name__	i'm amazed i've come up with this :)
18:17	amalloy	depending on how comfortable you are with destructuring, you can make it still-more readable
18:17	amalloy	&(fn fib [[a b]] [(+ a b) b])
18:17	sexpbot	⟹ #<sandbox11874$eval14090$fib__14091 sandbox11874$eval14090$fib__14091@b94d90>
18:18	__name__	amalloy: Thank you.
18:18	__name__	amalloy: I just meant to try that myself :)
18:19	__name__	i guess defn fibs [] (map second (iterate (fn [[x y]] [(+ x y) x]) [1 1]))) is too much of the good
18:19	amalloy	__name__: http://rosettacode.org/wiki/Fibonacci_sequence#Clojure
18:19	amalloy	is in fact what you've just done
18:20	__name__	Yep
18:20	amalloy	(i added the commented version a few months ago)
18:20	brehaut	,(let [f (lazy-cat [1 1] (map + ff (rest ff)))] (take 5 ff))
18:20	clojurebot	java.lang.Exception: Unable to resolve symbol: ff in this context
18:20	brehaut	i am a muppet
18:21	brehaut	,(let [f (lazy-cat [1 1] (map + f (rest f)))] (take 5 f))
18:21	clojurebot	java.lang.Exception: Unable to resolve symbol: f in this context
18:21	amalloy	anyway nice work __name__. it's impressive to come up with the strategy of using iterate to store temporary data
18:21	brehaut	unequivocally so apparently
18:21	__name__	amalloy: i started with recursion, and saw that it's no use for tail calls …
18:22	arohner	according to visualvm, it appears my app is spending a significant chunk of time in PersistentHashMap$HashCollisionNode.findIndex(). Are there any clever strategies for reducing the number of hash collisions in my data?
18:22	arohner	(I assume that hitting a different node type in PHashMap will improve my performance)
18:23	brehaut	__name__ the nerdy name for the solution you came up with is a hylomorphism
18:24	brehaut	(roughly)
18:25	brehaut	ie, converting a recursive algorithm into a stream generator and a stream consumer
18:26	__name__	brehaut: thank you for your elaboration. i appreciate it.
18:28	brehaut	__name__ no problem
18:31	brehaut	__name__: also, (nth n ...) is (first (drop n...))
18:32	brehaut	although i think i have the args backwards
18:32	__name__	I ended up with (defn fibs [] (map second (iterate (fn [[x y]] [(+ x y) x]) [1 0]))) by now
18:32	__name__	i had forgotten the 0
18:32	__name__	Am I right in believing that at any point in time there's only x and y in memory?
18:33	brehaut	yup
18:33	__name__	yay
18:34	__name__	thanks for putting up with my ignorance :)
18:35	brehaut	nah, ignorance is when you type stupid crap into clojure bot rather than a repl
18:35	brehaut	and then make the same mistake again
18:35	brehaut	__name__ how familiar are you with generators, generator expressions and itertools in python?
18:35	__name__	brehaut: very
18:36	amalloy	er, no. only x and y are required to be in memory. the gc won't clean them up till it needs to
18:36	__name__	amalloy: Oh; Sorry for being vague, I meant that.
18:37	amalloy	__name__: preface: i don't think the following is actually better than your version
18:38	amalloy	oh actually i take it back, this version is awesome
18:38	amalloy	you could implement (fn [[x y]] [(+ x y) x]) as (juxt (partial apply +) first))
18:39	__name__	amalloy: would you mind explaining, i looked at the doc of juxt (and know what partial does), but do not seem to grasp it.
18:40	brehaut	,((juxt inc dec) 1)
18:40	clojurebot	[2 0]
18:40	amalloy	well, ideally it would be just (juxt + first), which makes more sense
18:41	amalloy	but because [x y] is a list, you need to ##(apply + [1 2])
18:41	sexpbot	⟹ 3
18:41	__name__	amalloy: are you a haskeller?
18:41	amalloy	(partial apply +) wraps that up in a new function that will add the list it's passed
18:41	amalloy	__name__: no, but i keep hearing i should be
18:41	amalloy	i think point-free is nice
18:41	brehaut	the haskell solution ported to clojure is
18:42	brehaut	(def fibs (lazy-cat [1 1] (map + fibs (rest fibs))))
18:43	brehaut	turns out i was right previously but i (obviously) need a var in the road, to make it self recursive
18:43	amalloy	&with-local-vars
18:43	sexpbot	java.lang.Exception: Can't take value of a macro: #'clojure.core/with-local-vars
18:43	__name__	amalloy: I understand
18:44	brehaut	,(with-local-vars [fib (lazy-cat [1 1] (map + fibs (rest fibs)))] (take 10 fibs))
18:44	clojurebot	java.lang.Exception: Unable to resolve symbol: fibs in this context
18:45	amalloy	brehaut: the var doesn't exist until its init expr is done
18:46	brehaut	also i typod
18:46	amalloy	&(with-local-vars [fibs nil] (var-set fibs (lazy-cat [1 1] (map + (var-get) fibs (rest (var-get fibs))))) (take 10 (var-get fibs)))
18:46	sexpbot	java.lang.IllegalArgumentException: Wrong number of args (0) passed to: core$var-get
18:46	amalloy	blah whatever
18:47	amalloy	&(with-local-vars [fibs nil] (var-set fibs (lazy-cat [1 1] (map + (var-get fibs) (rest (var-get fibs))))) (take 10 (var-get fibs)))
18:47	sexpbot	java.lang.IllegalStateException: Var null/null is unbound.
18:47	brehaut	amalloy: im glad its not just me :/
18:47	arohner	more info on my hash collision problem. I have a map w/ 33k keys, but 6.7k distinct hash codes (according to (->> my-map keys (map #(.hashCode %)) distinct count
18:47	amalloy	&(with-local-vars [fibs nil] (var-set fibs (lazy-cat [1 1] (map + (var-get fibs) (rest (var-get fibs))))) (doall (take 10 (var-get fibs))))
18:47	sexpbot	⟹ (1 1 2 3 5 8 13 21 34 55)
18:47	__name__	yay
18:47	amalloy	brehaut: solved!
18:48	amalloy	vile though it is
18:48	brehaut	(inc amalloy )
18:48	sexpbot	⟹ 2
18:48	brehaut	woo :-)
18:48	brehaut	yeah remarkably so
18:48	brehaut	the basic concept is so tidy too
18:49	Leonidas	__name__: I'm not haskeller either and partial and thread-last are seriously nice ;)
18:49	amalloy	partial is...really handy, and way too verbose
18:49	__name__	Leonidas: oh hey
18:49	brehaut	amalloy: thats why we have % ;)
18:49	brehaut	err #
18:50	Leonidas	__name__: hi :)
18:50	Leonidas	__name__: I'm currently in clojure-hack mode :D
18:50	amalloy	one day i'll cross over to the dark side and (def ##(char (rand-int 0xffff)) partial)
18:50	sexpbot	⟹ \練
18:50	__name__	Leonidas: i'm in ‘i should go to sleep’ mode.
18:51	brehaut	amalloy: i apparently dont have that glyph
18:51	amalloy	brehaut: i don't either, it's too high in the code charts
18:51	Leonidas	__name__: same here. and "i should learn for exams" mode. this is the one time in the semester when I start to hack productively :)
18:51	__name__	Leonidas: :)
18:51	amalloy	&(char (rand-int 0x8fff))
18:51	sexpbot	⟹ \佗
18:51	brehaut	hah awesome
18:52	amalloy	although FAB0 is the best random character ever
18:52	amalloy	it's FAB0LOUS!
18:52	__name__	&(char 0xdead)
18:52	sexpbot	⟹ \?
18:53	Leonidas	,(char 0xFAB0)
18:53	clojurebot	\練
18:53	amalloy	that's how haskellers roll, isn't it? define single-unicode-character names for the useful functions?
18:53	Leonidas	which of these bots is actually to prefer?
18:54	brehaut	nah, its more like a like a crazy pipe of 2 to 5 punctiation characters as a binary op
18:54	amalloy	Leonidas: sexpbot imo, but i'm biased as i've been helping write/maintain him for months now
18:55	Leonidas	amalloy: :)
18:55	brehaut	amalloy: your homework is to explain the difference between (.) (>>>) and (>=>)
18:57	brehaut	valid answers do include 'not much'
18:58	arohner	&(.hashCode {62 0, 75 1720, 73 1})
18:58	sexpbot	⟹ 1913
18:58	arohner	&(.hashCode {75 1717, 62 1, 61 1})
18:58	sexpbot	⟹ 1913
18:59	amalloy	arohner: (hash x) is the same as (.hashCode x)
18:59	arohner	amalloy: thanks, but not my issue ATM
18:59	amalloy	laugh i know
18:59	arohner	&(hash {75 1099})
18:59	sexpbot	⟹ 1024
19:00	arohner	&(hash { 69 24 61 1 75 812})
19:00	sexpbot	⟹ 1024
19:00	arohner	I can do that 28k more times
19:00	arohner	out of 33k maps
19:01	amalloy	have you looked at the source of map.hash?
19:02	arohner	yeah. it doesn't look very random (though I could have told you that empirically )
19:02	amalloy	it looks like it's pretty bad, yeah
19:03	amalloy	arohner: you could probably make it sufficiently good just by adding hash *= 13 before the +=
19:05	amalloy	perhaps that just slows things down too much for rich
19:08	arohner	amalloy: if you think computing hashes is expensive, you should try dealing with hash-collisions :-)
19:08	arohner	amalloy: I'll try out a build with *= 13, and we'll see what happens
19:08	amalloy	arohner: that's only an issue if maps containing elements with weak hash functions are stored inside of another mapo
19:09	amalloy	so i doubt it comes up much in practice
19:09	arohner	&(hash 1238907)
19:09	sexpbot	⟹ 1238907
19:10	arohner	my data is not distributed randomly. The keys are db ids, and the values are ids of enums that users have selected
19:11	amalloy	arohner: yes, i understand why it comes up for you
19:12	amalloy	my point is that it may not come up often enough in general to merit slowing down map hashing; the hit there might be worse than the occasional reduction in collisions
19:16	__name__	thanks, especially amalloy and brehaut; good luck with the exam, Leonidas. good night all.
19:17	Leonidas	__name__: goodnight.
19:22	symuyn	Is a vector's hash code calculated when the vector is created, or is it lazily calculated when hash or = is called?
19:24	amalloy	symuyn: on hash
19:24	symuyn	When hash is called?
19:24	amalloy	yes
19:24	symuyn	Good, that makes sense
19:24	symuyn	By the way, does vector's isEquals use hash codes?
19:24	symuyn	isEqual, I mean
19:25	amalloy	symuyn: bizarrely enough, the answer is "sometimes"
19:25	symuyn	Hmm
19:26	amalloy	for List and PersistentVector, it checks their hash codes
19:26	amalloy	for Sequential objects it goes straight to comparing
19:26	symuyn	Aren't List and PersistentVector inside Sequential?
19:26	symuyn	Oh wait, they can override
19:27	symuyn	But what doesn't override Sequential.isEqual?
19:27	amalloy	&(some #{clojure.lang.Sequential} (supers (class [])))
19:27	sexpbot	⟹ clojure.lang.Sequential
19:27	symuyn	Yeah
19:27	symuyn	Oh well. Clojure does a good job of hiding this stuff anyway
19:28	amalloy	symuyn: the persistent data structures have a doEquiv and doEquals
19:28	symuyn	I forgot: are all Sequential objects persistent?
19:28	amalloy	equiv is what's called by (= foo bar), and it never checks hash codes b/c it needs [1 2] to equal (1 2)
19:29	symuyn	I thought that [1 2] and (1 2) had equal hash codes; I was told that yesterday
19:29	symuyn	@(= (hash [1 2]) (hash '(1 2)))
19:29	amalloy	they probably do, but that's not really a guarantee
19:30	symuyn	Ugh
19:30	symuyn	&(= (hash [1 2]) (hash '(1 2)))
19:30	sexpbot	⟹ true
19:30	amalloy	&(map hash ["" 1] #{"" 1})
19:30	sexpbot	java.lang.IllegalArgumentException: Wrong number of args (2) passed to: core$hash
19:30	mefesto	anyone use clojure-rabbitmq in here?
19:30	amalloy	&(map hash [["" 1] #{"" 1}])
19:30	sexpbot	⟹ (962 1)
19:31	amalloy	&(apply = [["" 1] #{"" 1}])
19:31	sexpbot	⟹ false
19:31	amalloy	well, that's good at least
19:31	amalloy	&(apply = [[1 ""] #{"" 1}])
19:31	sexpbot	⟹ false
19:31	amalloy	anyway i think it's a complicated issue
19:31	symuyn	Wait, really?
19:31	symuyn	&(= #{} [])
19:31	sexpbot	⟹ false
19:31	symuyn	Huh. Sets and vectors aren't equal.
19:32	symuyn	That might bite me someday
19:32	symuyn	I wonder what the rationale is
19:32	brehaut	symuyn: that makes sense though right? vectors have additional information encoded in them than sets
19:32	symuyn	Ah, right.
19:33	symuyn	I need to think of collection equality as sequence equality
19:33	symuyn	Wait, that might not work for sets to sets
19:33	brehaut	,[(hash (lazy-seq [1 2 3])), (hash (lazy-seq [3 2 1]))]
19:33	clojurebot	[30817 32737]
19:34	brehaut	i dont know why i made those lazy
19:34	amalloy	brehaut: an extra sprinkling of awesome
19:34	brehaut	amalloy: i like how you think
19:36	brehaut	symuyn: i think realistically you need to have much crisper notions of equality
19:38	symuyn	brehaut: I think that sequentials vs. non-sequentials are fine. "All sequentials are equal if blah, blah, but are never equal to non-sequentials. Non-sequentials are equal if they contain the same elements, but are never equal to sequentials."
19:38	brehaut	symuyn: what about a sorted set compared to a vector?
19:38	symuyn	&(= (sorted-set 1 2 3) [1 2 3])
19:38	sexpbot	⟹ false
19:39	symuyn	Yeah, okay
19:39	brehaut	yeah, and even worse
19:39	symuyn	Well, so much for consistency
19:39	brehaut	is (sorted-set 1 2 3) different to [1 2 2 3]?
19:40	symuyn	&(= (sorted-set 1 2 3) [1 2 2 3])
19:40	sexpbot	⟹ false
19:41	brehaut	really, you need to convert one side of your test into the other type
19:41	brehaut	,(= (sorted-set 1 2 3) (apply sorted-set [1 2 2 3]))
19:41	clojurebot	true
19:42	symuyn	Ugh, apply is so slow; it's been the bottleneck of my programs in the past
19:42	brehaut	,(= (vec (sorted-set 1 2 3)) [1 2 2 3])
19:42	clojurebot	false
19:42	symuyn	Thank goodness for vec
19:43	symuyn	Do you know if there's a way to turn off pre/post-conditions, like tests?
19:43	brehaut	symuyn: the point being though, depending on how you are viewing _the same data_ equivalence can change dramatically
19:43	symuyn	Yeah
19:43	brehaut	(same excluding collection information)
19:43	amalloy	&(time (apply + (range 1e5)))
19:43	sexpbot	⟹ "Elapsed time: 26.930893 msecs" 4999950000
19:44	amalloy	symuyn: apply really isn't slow, i don't see what problem you're experiencing
19:44	amalloy	&(time (reduce + (range 1e5)))
19:44	sexpbot	⟹ "Elapsed time: 30.868435 msecs" 4999950000
19:44	brehaut	amalloy: i imagine applying a collection constructor to a large collection is going to be a slow operation ;)
19:44	symuyn	amalloy: It happened twice a year ago. Perhaps I'm wrong, but I'm pretty confident
19:45	amalloy	brehaut: sure, but not any slower than (doall (map identity coll))
19:45	brehaut	amalloy: oh for sure, its not the result of apply that its slow
19:47	amalloy	symuyn: you found that (foo x y z) was substantially faster than (apply foo [x y z])? i guess i could see that, if foo had a lot of different arities defined
19:47	symuyn	Why would the number of arities matter?
19:49	brehaut	symuyn: a function call can choose the implementation at compile time, an apply call has to determine the implementation at runtime
19:50	symuyn	Yes, but does the search time depend on the number of arities? Maybe it's constant to the number. But the again, I've no idea.
19:52	brehaut	symuyn: i cant intuit how it could be constant time
19:53	brehaut	$source apply
19:53	sexpbot	apply is http://is.gd/AklWob
19:53	brehaut	i must confess to that not clearing things up for me
19:54	symuyn	The source there doesn't show the implementation of arity selection.
19:54	symuyn	It doesn't really matter that much anyway
19:54	symuyn	I'd think that we'd have to look in clojure.lang.IFn (or .Fn?) but I don't like looking in Clojure's guts
19:55	brehaut	https://github.com/clojure/clojure/blob/1.2.x/src/jvm/clojure/lang/AFn.java#L154
19:55	symuyn	Ah, now that's interesting
19:55	hiredman	,((fn [& x] (first x)) (iterate inc 0))
19:55	clojurebot	(0 1 2 3 4 5 6 7 8 9 ...)
19:55	hiredman	erm
19:55	hiredman	,(apply (fn [& x] (first x)) (iterate inc 0))
19:55	clojurebot	0
19:55	symuyn	Now, doesn't collection counting have near-constant-time?
19:55	hiredman	apply doesn't count
19:56	symuyn	Wait, no
19:56	hiredman	^- apply to an infinite seq
19:56	brehaut	apply does magic
19:56	symuyn	The arglist is an ISeq
19:56	symuyn	Sequence counting is linear
19:57	symuyn	hiredman: That's interesting
19:57	brehaut	https://github.com/clojure/clojure/blob/1.2.x/src/jvm/clojure/lang/RT.java#L1184
19:57	symuyn	That kind of boggles my mind, actually
19:57	symuyn	Yes, and there we have it
20:01	brehaut	also im presuming that Util.ret1 at https://github.com/clojure/clojure/blob/1.2.x/src/jvm/clojure/lang/AFn.java#L151 is used to let java release the seq?
20:03	hiredman	yes, java doesn't have a way of clearing the jvms method frame while keeping a reference on the method's stack
20:03	brehaut	hiredman: cheers
20:22	brehaut	symuyn: relevant to the discussion http://groups.google.com/group/clojure-dev/browse_thread/thread/c58ec42d78209ee0
20:24	symuyn	brehaut: Thanks; that's very interesting
20:24	symuyn	Oops, wrong punctuation
20:26	brehaut	symuyn: and by experimention i gather than sorted-sets test equality as sets by default, and seqs if you wrap them seq; YMMV of course, ididnt read the code
20:26	symuyn	I think you're right in that I should just convert to the same type before comparing
23:09	pdk	(doc doseq)
23:09	clojurebot	"([seq-exprs & body]); Repeatedly executes body (presumably for side-effects) with bindings and filtering as provided by \"for\". Does not retain the head of the sequence. Returns nil."
23:09	pdk	(doc while)
23:09	clojurebot	"([test & body]); Repeatedly executes body while test expression is true. Presumes some side-effect will cause test to become false/nil. Returns nil"
23:16	amalloy	that's a weird docstring for while
23:16	brehaut	is it weird that i didnt even know there was a while?
23:16	amalloy	"Presumes some side-effect will cause test to become false/nil" suggests that it is an error to write (while true (...)), because you are violating while's assumption/precondition
23:17	amalloy	brehaut: yeah, i've never used it either
23:17	pdk	it's an infinite loop at any rate
23:17	amalloy	pdk: clearly. but there's nothing wrong with writing an infinite loop if that's what you want
23:18	technomancy	be honest, who reads the docstring for while?
23:18	amalloy	technomancy: pdk, it seems
23:18	amalloy	and now me, to my chagrin
23:19	brehaut	is there an sexp-grep for clojure?
23:20	brehaut	(ie, for grepping clojure source)
23:20	amalloy	brehaut: how would that be different from plain old grep?
23:21	brehaut	amalloy: knows about trees rather than lines
23:21	brehaut	grep is probably the wrong term
23:21	brehaut	xpath is a better one
23:21	brehaut	sexpath
23:21	brehaut	probably didnt need to go there
23:21	amalloy	like...sgrep (if (magic))? it's not clear to me how i'd specify useful sexps for this
23:22	technomancy	sounds like you want a zipper
23:22	brehaut	yeah i probably do