#clojure – 2012-07-07

2012-07-07

00:00	duck1123	I've hit an odd issue in monger. If I insert, then find-map-by-id I get my document back. If I replace the insert with insert-and-return, I get nil. Anyone know what's up?
00:00	mthvedt	by deferring looking up symbols, rules can be immutable and you don't have any forward-declaring
00:01	duck1123	the one just calls the other, so I don't see what could be going on.
00:01	mthvedt	if you want recursive rules
00:01	mthvedt	i tried it the 'normal' way, and having to forward declare rules then go back and mutate the old ones, to get mutually recursive rules, just seemed… un-clojureish
00:02	mthvedt	grabbing the ns is also unclojure-ish, but IMO a lesser evil
00:02	ToxicFrog	Fair enough
00:03	ToxicFrog	Hmm.
00:03	ToxicFrog	The NPE is not limited to redefing 'name
00:03	mthvedt	yes, looks like redefining any clojure.core fn does it?
00:04	ToxicFrog	>.<
00:04	ToxicFrog	I would have thought that redefing any of those would just shadow the definition in clojure.core, since I'm in my own namespace here
00:06	mthvedt	Is the clojure team aware of this issue? It seems to be known in the google groups threads
00:07	mthvedt	is there a clojure JIRA or something to search?
00:07	mthvedt	it's known to happen in both lein and maven compilation
00:08	ToxicFrog	It does, in fact: http://dev.clojure.org/jira/secure/Dashboard.jspa
00:09	mthvedt	it does not happen except in precompiled code, so that and it being discouraged usage make it low on the radar probably
00:09	ToxicFrog	Back to Clearly for a moment -
00:09	mthvedt	ok
00:10	ToxicFrog	I'm trying to create rules for three token types. A typename is a sequence of uppercase letters; a key is any sequence of letters and numbers; and a value is any string at all not containing a newline.
00:10	ToxicFrog	In something like scala.util.parsing or flex+yacc, I'd just use regexes here.
00:10	ToxicFrog	In Clearly, I have this: https://gist.github.com/fb903793baa2e918aae0
00:10	ToxicFrog	Is there a better way to do this? Because this seems super awkward.
00:12	mthvedt	yup, clearley only eats one item of input at a time
00:12	ToxicFrog	(also, it would be really nice to be able to construct rules from regexes, specifically for this sort of thing)
00:12	ToxicFrog	So is it expected to be paired with a lexer?
00:12	mthvedt	doesn't need to be, though you can if you want to
00:13	ToxicFrog	Well, yes, it doesn't need to be, but it looks like it would make stuff like this a lot simpler
00:13	mthvedt	the earley algorithm can be modified to scan multiple items in one low-level rule… it's fairly easy, but it's nontrivial
00:13	ToxicFrog	There's a lot of code in the json parser as well working around this
00:13	mthvedt	it's on my "todo" list
00:14	mthvedt	try
00:14	mthvedt	i
00:14	mthvedt	instead of having 9 lines
00:14	mthvedt	scanner and one-or-more both return rules
00:14	mthvedt	so i think you can do (def x (one-or-more y (scanner z)))
00:15	mthvedt	once the rule API is cleaned up, you could just write a clearly regex parser that emits a clearly rule :)
00:15	mthvedt	and by you, i mean me
00:15	ToxicFrog	What is y meant to be there? I'm still a bit shaky on "rule heads".
00:16	ToxicFrog	Well, yes, I was contemplating how hard it would be for me to do, given the current state of Clearley :P
00:16	mthvedt	oh sorry
00:16	mthvedt	(def x (one-or-more (scanner y z))) is what i meant to type
00:16	mthvedt	(def sfs-type (one-or-more (scanner #(…) identity)))
00:17	mthvedt	try that
00:17	ToxicFrog	That works fine, thanks
00:17	ToxicFrog	And is easily macroized too.
00:18	ToxicFrog	And now that the parser compiles, my super major #1 feature request: useful error reporting when a parse fails.
00:18	ToxicFrog	This is my #1 reason for using a parsing library rather than just rolling my own recursive descent parser: error reporting.
00:20	mthvedt	yeah, about that...
00:21	mthvedt	i hope you don't have to throw your work away… clearly has almost no error reporting at this time
00:22	mthvedt	or when you say that's a feature request, you just mean, would be very nice to have?
00:23	ToxicFrog	For this project, it's not a priority, since this project is actually a rewrite of an existing codebase with no real urgency. So if I have to wait for error reporting to be added, or even add it myself, it's not a big deal.
00:24	mthvedt	ok, cool
00:24	ToxicFrog	Also because I'm the only user of this program who actually cares about parse errors, since the stuff it's processing is all machine-generated and all the end users need to do is report parse errors as a bug to me if they occur.
00:24	ToxicFrog	For projects where this is not the case, yeah, it would be a serious issue.
00:25	mthvedt	yup
00:25	mthvedt	one attractive thing about bottom-up parsers is error reporting is a lot more natural...
00:28	ToxicFrog	For reference, errors from scala.util.parsing - which are, so far, the best I've seen - take the form:
00:28	ToxicFrog	[29.1] failure: string matching regex `= [^\n]' expected but `a' found
00:28	ToxicFrog	Followed by the offending line, and a carat pointing out the exact location in the line.
00:28	ToxicFrog	(this is generated by a method on the error object; all of this information can be extracted by the program easily as well)
00:29	mthvedt	i've never used scale's parsing library, but it looks very nice
00:29	mthvedt	isn't it top-down, though? i wonder how they make sense of errors
00:30	ToxicFrog	To be honest, I have no idea
00:30	ToxicFrog	The source is available from http://www.scala-lang.org/api/current/scala/util/parsing/combinator/Parsers.html if you feel like crowbarring it open and looking inside, although I doubt much if any of it will be relevant to an Earley parser.
00:32	ToxicFrog	Of course, it's also worth noting that the top-level Parser.scala - not even any of the concrete implements like RegexParser - is almost as large as all of Clearley including the tests
00:32	ToxicFrog	Scala's standard library is not exactly lightweight.
00:33	mthvedt	working with top-down parsers is what drove me to bottom-up parsers in the first place :P
00:33	mthvedt	we had a use case at work that involved a complex, highly mutually recursive grammar
00:33	mthvedt	existing grammars, even those that advertised the ability to handle left recursion, just all blew up
00:34	ToxicFrog	I haven't observed such issues with Scala's parsers, but I've never tried parsing anything super complex with them
00:34	mthvedt	anyway, i really gotta get some rest soon...
00:35	ToxicFrog	Ok. Now to actually fix this so that it works
00:35	ToxicFrog	Since what prompted me to mention error messages was that my parse is failing (because it does no whitespace handling at present)
00:35	ToxicFrog	Hmm. Maybe I should give it a lexer.
00:37	mthvedt	if you're too lazy to handle whitespace… s/\s+/ /g :P
00:37	ToxicFrog	mthvedt: problem with that is, note the rule for sfs-value
00:37	ToxicFrog	It's everything from the = to the end of line preserving whitespace
00:38	mthvedt	there's some whitespace rules in the json example
00:39	ToxicFrog	Yeah; it gets kind of messy.
00:40	ToxicFrog	This'll be good practice; it's been ages since I wrote a divided lexer/parser
00:58	ToxicFrog	Huh
00:59	ToxicFrog	I can do this: #(Character/isLetterOrDigit %)
00:59	ToxicFrog	But I can't do this: (partial Character/isLetterOrDigit)
01:03	mthvedt	toxicfrog: because java methods are not clojure fns
01:04	mthvedt	they are actually clojure special forms
01:05	ToxicFrog	Oh :(
01:05	ToxicFrog	Am I pretty much limited to #() and equivalents for that, then?
01:06	mthvedt	pretty much
02:51	aperiodic	i think that's part of why point-free style is not really used as much in clojure--if you use #(), you don't have to keep 'is this a special form?' in the back of your mind
02:53	aperiodic	on a related note, i ended up writing andf & orf (the fn versions of and and or) the other day, which felt a bit odd to me
02:53	amalloy	as well it should
02:55	amalloy	&(let [andf (comp (partial every? identity) list)] (andf true false))
02:55	lazybot	⇒ false
02:55	amalloy	&(let [andf (comp (partial every? identity) list)] (andf true true))
02:55	lazybot	⇒ true
02:55	aperiodic	man, whenever i do some thing weird with HOFs i should just come here and bug you
02:56	amalloy	my point isn't really the allegedly-clever definition of andf using comp/partial, it's that you should just use every? and some instead of andf and orf
03:02	aperiodic	the reason i ended up writing them was to construct the predicate i wanted to pass to things like every? and some
03:03	aperiodic	andf and orf are functions on predicates, not booleans
03:04	amalloy	so you're saying they're some-fn and every-pred?
03:05	aperiodic	yeah, that's what i'm saying
03:05	amalloy	&(doc some-fn)
03:05	lazybot	⇒ "([p] [p1 p2] [p1 p2 p3] [p1 p2 p3 & ps]); Takes a set of predicates and returns a function f that returns the first logical true value returned by one of its composing predicates against any of its arguments, else it returns logical false. Note that f is short-... https://www.refheap.com/paste/3505
03:05	amalloy	&(doc every-pred?)
03:05	lazybot	java.lang.RuntimeException: Unable to resolve var: every-pred? in this context
03:05	amalloy	&(doc every-pred)
03:05	lazybot	⇒ "([p] [p1 p2] [p1 p2 p3] [p1 p2 p3 & ps]); Takes a set of predicates and returns a function f that returns true if all of its composing predicates return a logical true value against all of its arguments, else it returns false. Note that f is short-circuiting in... https://www.refheap.com/paste/3506
03:50	wubino	any good reads on creating a pastebin like service?
04:05	borkdude	wubino check out https://github.com/Raynes/refheap and www.refheap.com
04:27	ro_st	are there any compelling reasons NOT to use immutant?
04:27	ro_st	put another way, what's the catch?
04:28	hiredman	I wonder how well it would work in a heterogeneous environment
04:29	ro_st	ok, so one thing is you couldn't do is host on something like heroku
04:29	hiredman	in some sense it is waiting for some one to take a chance on it, I haven't heard of anyone using it "in production" yet
04:31	ro_st	it's still pretty new
04:31	hiredman	yeah, but interest is building, and it is gaining features, someone will give it a trial by fire
04:32	ro_st	not having to build out all the stuff it provides is quite compelling
04:32	hiredman	yes, but at work we've already built all that stuff :)
04:32	clojurebot	http://haacked.com/images/haacked_com/WindowsLiveWriter/IConfigMapPathIsInaccessibleDueToItsProt_1446B/works-on-my-machine-starburst.png
04:33	hiredman	a lot of features seemed to be sort of aimed at webapps instead of backend data processing apps
04:33	ro_st	perfect for us
04:33	ro_st	i'm in the process of writing a json api, and shortly will be needing to port ruby/resque based stuff for messaging over
04:38	hiredman	the custering stuff would be really cool, but I would prefer to be able to swap out discovery mechanisms (just use zookeeper)
04:39	hiredman	I don't trust the jgroups stuff
04:39	ro_st	i reckon it's worth playing with
04:40	ro_st	gotta run!
05:22	_ulises	morning all, I have a question about midje background; basically, if I define (against-background :facts (some-fn)...) and then have (fact (f) => 1 (g) => 2), then (some-fn) is executed twice. Maybe I'm not properly understanding (fact ...) vs (facts ...)? My objective is to start a web server before running tests and to bring it down once I'm done testing. I managed to do this with (against-background :contents ...)
08:38	AWizzArd	Protocol experts wanted: I have a Protocol which I want to implement for IFns and Maps. Now, a Clojure map is at the same time an IFn. When I now call (my-proto-fn {}) I end up in the body specified for IFns. But I want to call the my-proto-fn for java.util.Maps. Ideas?
08:39	AWizzArd	(defprotocol Bar (foos [x])) and then (extend-protocol Bar clojure.lang.IFn (foos [x] (println :fn)) java.util.Map (foos [x] (println :map)))
08:40	AWizzArd	Now I want that (foos {}) prints :map.
09:22	daniel___	im looking for the most concise way of checking if all the values in a list equal something?
09:22	daniel___	,(map #(= % 1) '(1 2 3 4 5))
09:22	clojurebot	(true false false false false)
09:22	daniel___	,(contains? false (map #(= % 1) '(1 2 3 4 5)))
09:22	clojurebot	false
09:23	daniel___	,(apply #(= true %) (map #(= % 1) '(1 2 3 4 5)))
09:23	clojurebot	#<ArityException clojure.lang.ArityException: Wrong number of args (5) passed to: sandbox$eval87$fn>
09:23	madsy	daniel___: Maybe every?
09:23	daniel___	madsy maybe
09:24	daniel___	,(every? true (map #(= % 1) '(1 2 3 4 5)))
09:24	clojurebot	#<ClassCastException java.lang.ClassCastException: java.lang.Boolean cannot be cast to clojure.lang.IFn>
09:24	daniel___	,(every? #(= true %) (map #(= % 1) '(1 2 3 4 5)))
09:24	clojurebot	false
09:24	daniel___	:)
09:37	inklesspen	daniel___: you can just do (every? #(= % 1) '(1 2 3 4 5)) looks like. or (every? (partial = 1) '(1 2 3 4 5))
09:40	_ulises	,(apply and (map #(= 1 %) [1 2 3]))
09:40	clojurebot	#<CompilerException java.lang.RuntimeException: Can't take value of a macro: #'clojure.core/and, compiling:(NO_SOURCE_PATH:0)>
09:41	_ulises	,(reduce and (map #(= 1 %) [1 2 3]))
09:41	clojurebot	#<CompilerException java.lang.RuntimeException: Can't take value of a macro: #'clojure.core/and, compiling:(NO_SOURCE_PATH:0)>
09:44	_ulises	shame that and is a macro, otherwise it'd be great to reduce your checks using and
09:45	inklesspen	,(apply (partial = 1) '(1 1 1 1))
09:45	clojurebot	true
09:46	inklesspen	,(apply (partial = 1) '(1 2 3 4))
09:46	clojurebot	false
09:46	_ulises	lovely
09:48	AWizzArd	Well, inklesspen already showed the ideomatic solution, which is: (every? #(= 1 %) [1 2 3 4 5])
09:48	AWizzArd	_ulises: the function equivalent to `and` is `every?`.
09:49	inklesspen	AWizzArd: is the anonymous function version any more ideomatic than the partial version?
09:49	inklesspen	i guess it's shorter
09:49	AWizzArd	inklesspen: both are okay, but partial is evaluated each time.
09:49	inklesspen	ah
09:49	inklesspen	makes sense
09:49	AWizzArd	While (fn [n] (= n 1)) is directly compiled, and thus a bit more efficient.
09:50	AWizzArd	Plus: I personally find it more readable.
09:50	AWizzArd	For this specific case one could do some trickery, such as (= #{1} (set [1 2 3 4 5]))
09:50	AWizzArd	But this would just check if every element in the seq is =1
09:51	AWizzArd	The solution with every? is more generic, and could be used as well for (every? odd? some-numbers)
10:11	ToxicFrog	Hmm. I wish I could ^Tag strings.
10:14	mthvedt	toxicfrog: good morning
10:14	ToxicFrog	'morning
10:15	mthvedt	has the parser been working out ok?
10:16	ToxicFrog	I went to bed at about the same time as you last night; I'm just starting on the lexer now
10:16	ToxicFrog	Although I did think of a lexer-related question
10:16	mthvedt	shoot
10:16	ToxicFrog	When using defrule, a rule is of the form [terminal-or-nonterminal+], where a nonterminal is another rule, and a terminal is - when parsing a string - a single character
10:17	ToxicFrog	Eg, [\{ keyvalues \}]
10:17	ToxicFrog	How is that single character matched, and what does it need to be replaced with when parsing a stream of { :tag :foo :text "bar" } tokens?
10:17	ToxicFrog	I think that using a scanner that checks :tag would work, so you do something like:
10:18	ToxicFrog	(def open-brace (scanner #(= (:tag %) :open-brace) identity))
10:18	ToxicFrog	And then use [open-brace keyvalues close-brace]
10:18	mthvedt	matched with =
10:18	ToxicFrog	But is there a better way?
10:19	mthvedt	there's support for what i'm currently calling "tokenizers"
10:19	mthvedt	i
10:19	mthvedt	i'm not sure if they're a good idea, and might change/remove them
10:19	mthvedt	but basically, to test for a terminal symbol x
10:19	mthvedt	t
10:20	mthvedt	the parser runs (= x (tokenizer input))
10:20	mthvedt	where the default tokenizer is identity
10:21	mthvedt	that's still a little cumbersome, because each parse action needs to have :text in it anyway
10:22	mthvedt	you pass the tokenizer fn to build-parser
10:23	mthvedt	(build-parser goal-rule tokenizer)
10:23	ToxicFrog	Hmm
10:23	ToxicFrog	The issue I see there is that the tokenizer would (at least, I would expect) return not just the name of the input symbol but a whole bunch of information
10:24	ToxicFrog	{ :tag :number :text "12.34" :line 5 :col 8 }
10:24	ToxicFrog	And for matching, you only actually care about :tag; :line and :col are for the error reporter and :text is for whatever processes the AST.
10:25	mthvedt	you could pass :tag as your tokenizer
10:25	mthvedt	if your input symbols are maps you want to parse the :tags of
10:27	ToxicFrog	Ok, but in that case, is the return value of the rule just the :tag, or the entire map originally passed to tokenizer?
10:28	mthvedt	the return value will be the entire map
10:29	ToxicFrog	Awesome
10:36	augustl	is it possible to access the persistent data structures from ClojureScript in a Node.js app, without converting my app to ClojureScript?
10:36	nDuff	augustl: it'll be easier to have your ClojureScript code export to native structures.
10:37	augustl	I don't have any ClojureScript code :)
10:37	augustl	I could use persistent data structures though
10:37	augustl	ah, I see
10:37	nDuff	augustl: ...oh, you mean you want to _create_ them from native JS code, not just leverage them?
10:38	augustl	yes
10:38	augustl	similar to how you can create PersistentVector etc from java (right?)
10:38	nDuff	Hmm. Well, there's nothing stopping you from calling cljs.core.PersistentVector.fromArray() from native JavaScript
10:39	augustl	is cljs.core etc. available as one JavaScript file somewhere?
10:39	nDuff	augustl: ...run a compilation pass, and the output is one JavaScript file.
10:40	augustl	cool, thanks
10:40	nDuff	(when compiling with lein-cljsbuild, anyhow)
10:41	augustl	writing some code where my client for a server needs to get all state, even when it goes down
10:41	augustl	datomic-esque time semantics with persistent data would make sense for that I think
10:42	augustl	a client having to be present at all times to track state as it flows is pretty horrible. Would be much better if a client gets a ping, and then requests the state changes from time at last fetch to now
11:44	ToxicFrog	What's idiomatic for "find the first value in a coll satisfying p"?
11:45	ToxicFrog	(first (filter p coll)) ?
11:47	hyPiRion	ToxicFrog: Yeah.
11:54	ToxicFrog	I keep wanting to call it "first" or "find", but clojure already uses both of those @.@
11:58	Sorella	ToxicFrog, find-first?
12:00	ToxicFrog	Sorella: yeah, that's what I went with.
12:01	ToxicFrog	(I'm coming from a collections library which uses head/tail rather than first/rest, and (find p xs) finds the first x in xs satisfying p)
12:01	TimMc	ToxicFrog: While you're at it, you could add an optional not-found argument.
12:05	daniel___	((a b c) (d e f) (g h i)) is there an ingenius way of testing if a = e = i?
12:05	daniel___	ingenious*
12:06	daniel___	or c = e = g
12:07	daniel___	with pattern matching perhaps
12:07	TimMc	core.match is still extremely alpha (buggy), unfortunately.
12:08	daniel___	,(let [((a _ _) (_ b _) (_ _ c)) ((1 2 3)(1 2 3)(1 2 3))] (println a b c))
12:08	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.Exception: Unsupported binding form: ((a _ _) (_ b _) (_ _ c))>
12:08	hyPiRion	both a = e = i or c = e = g?
12:08	daniel___	yeah
12:08	hyPiRion	use vectors instead
12:08	TimMc	&(#(let [[[a] [_ b] [_ _ c]] %] [a b c]) '((1 2 3)(4 1 6)(7 8 1)))
12:08	hyPiRion	,(let [((a _ _) (_ b _) (_ _ c)) ((1 2 3)(1 2 3)(1 2 3))] (println a b c))
12:08	lazybot	⇒ [1 1 1]
12:08	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.Exception: Unsupported binding form: ((a _ _) (_ b _) (_ _ c))>
12:08	daniel___	hyPiRion: if i had a vector of length 9?
12:09	hyPiRion	What TimMc wrote.
12:09	daniel___	cool
12:09	daniel___	pattern matching only works with vectors?
12:09	TimMc	daniel___: map, nth, apply
12:09	TimMc	map-indexed, really
12:10	TimMc	daniel___: destructuring syntax uses vectors, but can be applied to any collection
12:10	daniel___	i c
12:10	daniel___	,(let [[[a _ _] [_ b _] [_ _ c]] ((1 2 3)(1 2 3)(1 2 3))] (println a b c))
12:10	clojurebot	#<ClassCastException java.lang.ClassCastException: java.lang.Long cannot be cast to clojure.lang.IFn>
12:10	daniel___	,(let [[[a _ _] [_ b _] [_ _ c]] '((1 2 3)(1 2 3)(1 2 3))] (println a b c))
12:10	clojurebot	1 2 3
12:10	daniel___	cool
12:11	TimMc	&(#(map-indexed (fn [i el] (nth el i)) %) '((1 2 3)(4 5 6)(7 8 9)))
12:11	lazybot	⇒ (1 5 9)
12:12	TimMc	&(#(map-indexed (fn [i el] (nth el (- (count %) i 1))) %) '((1 2 3)(4 5 6)(7 8 9)))
12:12	lazybot	⇒ (3 5 7)
12:13	daniel___	neat
12:13	TimMc	&(apply = '(3 5 7))
12:13	lazybot	⇒ false
12:14	daniel___	any advantage over the destructuring approach?
12:14	TimMc	Extensible.
12:15	TimMc	This gets you diagonals of any length.
12:15	daniel___	the disadvantage i can see is that it is less explicit, i mean it takes a few moments longer to work out what its doing
12:15	TimMc	That's why you (defn diagonal ...) and use that.
12:43	daniel___	Can anyone create a neat way of doing this, in a similarly extensible way as before? [a b c d e f g h i] -> ((a d g) (b e h) (c f i))
12:44	daniel___	Perhaps there is already a function to achieve something like this, or with partition-by and map-indexed somehow?
12:44	metellus	,(partition 3 [a b c d e f g h i])
12:44	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve symbol: a in this context, compiling:(NO_SOURCE_PATH:0)>
12:44	metellus	,(partition 3 [1 2 3 4 5 6 7 8 9])
12:44	clojurebot	((1 2 3) (4 5 6) (7 8 9))
12:45	daniel___	yeah, im looking at the padding
12:45	AWizzArd	alternatively (partition-all 3 your-list)
12:45	daniel___	(partition 3 3 [1 2 3 4 5 6 7 8 9])
12:45	daniel___	,(partition 3 3 [1 2 3 4 5 6 7 8 9])
12:45	clojurebot	((1 2 3) (4 5 6) (7 8 9))
12:45	daniel___	thats not what i need
12:45	AWizzArd	,(partition-all 3 (range 10))
12:45	clojurebot	((0 1 2) (3 4 5) (6 7 8) (9))
12:45	daniel___	i need ((1 4 7) (2 5 8) ..
12:46	AWizzArd	,(apply map first (partition-all 3 (range 10)))
12:46	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: clojure.lang.ArityException: Wrong number of args (4) passed to: core$first>
12:46	daniel___	,(partition 3 3 3 [1 2 3 4 5 6 7 8 9])
12:46	clojurebot	((1 2 3) (4 5 6) (7 8 9))
12:46	daniel___	,(partition 3 3 3 3 [1 2 3 4 5 6 7 8 9])
12:46	clojurebot	#<ArityException clojure.lang.ArityException: Wrong number of args (5) passed to: core$partition>
12:47	daniel___	,(partition 3 1 3 [1 2 3 4 5 6 7 8 9])
12:47	clojurebot	((1 2 3) (2 3 4) (3 4 5) (4 5 6) (5 6 7) ...)
12:47	dustingetz	o you know how to map over a tree? i want to define functions like "bfs" "dfs" "iterative deepening search" that turn a tree into a lazy seq i can map over
12:47	dustingetz	*"does anyone know how to map over a tree"
12:47	AWizzArd	Maybe this:
12:47	AWizzArd	(apply map list (partition 3 (range 1 10)))
12:47	dustingetz	i think this is an example in haskell: http://okmij.org/ftp/continuations/Searches.hs - but i don't understand this
12:47	AWizzArd	,(apply map list (partition 3 (range 1 10)))
12:47	clojurebot	((1 4 7) (2 5 8) (3 6 9))
12:47	daniel___	there we go
12:47	daniel___	:D
12:47	daniel___	thanks
12:48	dustingetz	yeah but i want to define functions like 'bfs' 'dfs' which control the order in which i map
12:48	metellus	,(zipmap (partition 3 [1 2 3 4 5 6 7 8 9]))
12:48	clojurebot	#<ArityException clojure.lang.ArityException: Wrong number of args (1) passed to: core$zipmap>
12:48	metellus	,(apply zipmap (partition 3 [1 2 3 4 5 6 7 8 9]))
12:48	clojurebot	#<ArityException clojure.lang.ArityException: Wrong number of args (3) passed to: core$zipmap>
12:48	AWizzArd	metellus: partition 2
12:49	AWizzArd	No, nonsense. I mean: zipmap needs two args.
12:50	metellus	too bad
12:51	wingy	you think this is still valid for learning clj 1.4: https://peepcode.com/products/functional-programming-with-clojure
12:51	wingy	from 2009
12:51	wingy	hm probably not
12:51	wingy	3 years old afterall
12:53	wingy	do we have any from Stockholm here?
13:01	ohpauleez	dustingetz: Take a look at the kibit code
13:01	ohpauleez	We use clojure.walk
13:01	ohpauleez	and you can post and pre walk a tree
13:01	ohpauleez	we also have a function for seq'ing the tree
13:04	dustingetz	thanks paul
13:04	ohpauleez	&(doc tree-seq)
13:04	lazybot	⇒ "([branch? children root]); Returns a lazy sequence of the nodes in a tree, via a depth-first walk. branch? must be a fn of one arg that returns true if passed a node that can have children (but may not). children must be a fn of one arg that returns a sequence ... https://www.refheap.com/paste/3508
13:05	ohpauleez	np
13:19	weavejester	technomancy: I'm glad you pointed out "lein deploy" to me! Thanks!
13:20	ToxicFrog	I wish 'lein deploy' could deploy to github
13:21	ToxicFrog	(using the github upload-file thingy, I mean, not 'git push')
13:23	ohpauleez	ToxicFrog: There's documentation on how to host a maven repo on github, so technically ...
13:24	ToxicFrog	ohpauleez: yeah, but I don't want to host a maven repo, I just want to be able to upload release packages from the command line :P
13:39	ToxicFrog	Count number of items in xs satisfying p: (count (filter p xs)) ?
13:54	AWizzArd	ToxicFrog: yes.
14:20	wingy	why no def- like defn-
14:20	wingy	but for vars
14:21	amalloy	defn- only exists because, long ago, it was inconvenient to put :private metadata on your functions
14:21	wingy	amalloy: is it still inconventient?
14:22	amalloy	defining a new top-level name for every little thing you want to change leads to an explosion of new names: what about defmacro-? and defn-, if we decide should be for :dynamic?
14:22	amalloy	not at all. just (defn ^:private foo [])
14:23	wingy	true
14:23	wingy	but isn't it better to just use that line then?
14:23	wingy	and remove defn- to keep things consistent?
14:24	amalloy	it's unlikely to ever get removed, for compatibility
14:24	wingy	ok
14:24	wingy	i guess convenience is good as well
14:24	amalloy	but every few months someone asks on the mailing list if they can please have def-, and the response is primarily "no, defn- is bad enough"
14:25	wingy	just like you can put a doc string with def instead of having to assign a meta doc each time
14:25	wingy	but i do think if you really want to remove something bad you can do it by deprecating it
14:26	wingy	and have it there for 1-2 more versions .. better to progress forward in the longer run
14:34	Chouser1	Anyone know why the light table sandbox might be failing for me?
14:35	Chouser1	The browser console says "Firefox can't establish a connection to the server at ws://localhost:8833/socket."
14:35	TimMc	Chouser1: Try chrome.
14:35	TimMc	It seems to work on only some (random) versions of recent Firefoxen.
14:36	Chouser1	this is firefox 15.0a2
14:42	Chouser1	TimMc: Thanks, chrome is working.
15:23	ssutch	what is the recommended way to provide configuration values to a compojure app?
15:23	ssutch	eg, database URIs and whatnot
15:25	arohner	ssutch: you have a lot of options. Depends on the app, mainly
15:25	ssutch	my main deployment target is a uber war deployed on elastic beanstalk
15:25	ssutch	that's where i want to run it
15:26	ssutch	i need to provide it with db uri(s) and private keys and such
15:26	arohner	I like a bash file full of export FOO=bar
15:26	arohner	then source it before running
15:27	arohner	if you don't mind your config being checked in, you can write a clojure file that's just (def config {:foo bar}), and load that
15:28	ssutch	ok
15:28	ssutch	i'm fine with providing it to the command line
15:28	ssutch	i guess my only concern is things like a private key
15:29	arohner	so just export the path to the key
15:30	piotr	ssutch: hi. Env variable is the recommended way to do on Heroku. See https://devcenter.heroku.com/articles/config-vars
15:32	kmicu	ssutch: also check this out https://github.com/drakerlabs/milieu
15:33	ssutch	interesting
15:54	antares_	Spyglass now has a doc website: http://clojurememcached.info
15:55	antares_	and clojurewerkz.org has a new About page (retweets are greatly appreciated): https://twitter.com/ClojureWerkz/status/221681163641688065
16:00	daniel___	https://gist.github.com/3067920 play is my main entry point, i keep getting nullpointerexception with 'lein run'
16:00	daniel___	something to do with the read-line
16:01	daniel___	can anyone enlighten me?
16:02	antares_	daniel___: read-line can return nil
16:02	daniel___	yes, but its not prompting
16:03	antares_	actually, disregard, I think it returns empty strings
16:03	antares_	daniel___: do you have an example stack trace?
16:04	daniel___	added to the gist
16:06	dnolen	,(dec nil)
16:06	clojurebot	#<NullPointerException java.lang.NullPointerException>
16:06	dnolen	daniel___: your read-int can nil
16:06	raek	how can I run a ghci repl in a cabal project?
16:07	dnolen	raek: wrong channel ;)
16:07	dnolen	daniel___: I mean your read-int can return nil
16:08	daniel___	dnolen: if i take away the dec, i get an argument error
16:08	amalloy	console input doesn't work in lein run
16:08	daniel___	for some reason it isnt prompting
16:08	daniel___	oh
16:08	amalloy	try lein trampoline run
16:08	daniel___	amalloy: works
16:08	daniel___	:)
16:09	daniel___	whats trampoline?
16:11	daniel___	nvm, i see it runs it after leiningens jvm has closed
16:11	daniel___	rather than in a subprocess
16:27	technomancy	antares_: we used neocons at seajure the other night; it was great
16:28	antares_	technomancy: oh, nice!
16:28	technomancy	we loaded up the clojuresphere data set into it
16:29	antares_	technomancy: big people are using clojurewerkz libraries! :)
16:29	technomancy	yeah, like me. I'm 202cm.
17:05	mjewkes	Hey Everyone. I'm running OSX with Emacs 24. I've installed lein and added 1.4.4 of lein-swank to the profiles.clj file. I've installed clojure mode in emacs and it is doing syntax highlighting properly. But emacs doesn't seem to have the clojure-jack-in command available.
17:05	mjewkes	Has anyone bumped into this before?
17:07	amalloy	sounds like an old clojure-mode?
17:08	mjewkes	possibly - I just installed it using package-install.
17:08	amalloy	try getting it fresh from technomancy's github
17:08	mjewkes	Interestingly - slime-connect seems to be missing to.
17:09	mjewkes	Should that be present - amalloy: will do.
17:09	amalloy	i dunno. i think jack-in provides its own copies of the slime libs
17:25	antares_	yes, swank-clojure bundles its own copy of slime
17:26	Pupeno_W	From https://github.com/technomancy/swank-clojure/blob/master/README.md: "Add [lein-swank "1.4.4"] to the :plugins section of either project.clj or your user profile."
17:27	Pupeno_W	What does your profile mean here?
17:27	mjewkes	~/.lein/profiles.clj
17:27	clojurebot	/.lein/profiles.clj is nice, but it doesn't allow you to vary the profile for a specific project without checking it in to the repo
17:28	Pupeno_W	Thanks.
17:34	ToxicFrog	Oh bollocks
17:34	ToxicFrog	(drop n s) where s is a string returns a LazySeq
17:34	ToxicFrog	With tragic results when you're doing something like (re-match pattern (drop header-length buf))
17:37	metellus	use subs
17:37	ToxicFrog	Yeah, I was reflexively trying to make this sequence-type-agnostic
17:37	ToxicFrog	Despite the fact that, on reflection, it makes sense only for strings
18:04	overstood	I have what is hopefully a basic syntax question about Clojure, is this the right place for that?
18:05	ohpauleez	overstood: sure, totally
18:06	overstood	Great :)
18:10	overstood	So there is a function that normally it takes a number, does a thing to it and returns a value. There are some edge cases where this function needs to just return a constant because the behavior of that function is not covered by the algorithm that handles most cases. I'm currently using a lot of (if (eq input foo) constant (if (eq input foo2) constant2 (normalAlgorithm input)))
18:10	overstood	is there a better/more elegant way to do this than chaining if statements together?
18:10	ohpauleez	cond
18:11	ohpauleez	or condp
18:11	ohpauleez	&(doc cond)
18:11	lazybot	⇒ "Macro ([& clauses]); Takes a set of test/expr pairs. It evaluates each test one at a time. If a test returns logical true, cond evaluates and returns the value of the corresponding expr and doesn't evaluate any of the other tests or exprs. (cond) returns nil."
18:11	ohpauleez	http://clojuredocs.org/clojure_core/clojure.core/cond
18:12	ohpauleez	You might also want to consider `case`
18:12	ohpauleez	http://clojuredocs.org/clojure_core/clojure.core/case
18:12	ohpauleez	http://clojuredocs.org/clojure_core/clojure.core/condp
18:12	ohpauleez	there's condp
18:13	overstood	That looks like what I was looking for.
18:13	overstood	Thanks a lot!
18:14	amalloy	case would work, or you could just use a map
18:15	amalloy	(let [defaults {1 "one" 2 "two"}] (defn compute [x] (or (defaults x) (do-real-work x))))
18:16	overstood	that's neat too
18:16	ohpauleez	using a dispatch table like that is a pretty typical pattern overstood
18:18	mcohen	hi there #clojure. trying to get started programming Clojure and am getting stuck trying to compile, test, or repl with lein
18:19	mcohen	DEBUG output shows Classpath: /Users/mcohen/.lein/self-installs/leiningen-2.0.0-preview7-standalone.jar
18:19	mcohen	and everyone of those lein commands i listed above yields Exception in thread "main" java.lang.NoClassDefFoundError:
18:19	mcohen	and a stacktrace
18:19	mcohen	Caused by: java.lang.ClassNotFoundException:
18:19	mcohen	at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
18:19	mcohen	at java.security.AccessController.doPrivileged(Native Method)
18:19	mcohen	at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
18:19	mcohen	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
18:19	mcohen	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
18:19	mcohen	at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
18:19	mcohen	Compilation failed.
18:20	mcohen	i know i must be missing something simple and stupid
18:20	mcohen	can anyone help please?
18:21	ohpauleez	cd to a different directly, like you $HOME
18:21	ohpauleez	then try lein2 repl
18:21	ohpauleez	do you still get the error?
18:21	overstood	I'm just starting to learn functional programming (I'm coming from a pretty strong OO background). It's definitely an interestint paradigm shift. I feel a bit overwhelmed by the amount of power in relatively terse statements.
18:22	overstood	Why would one use cond vs a dispatch table?
18:22	mcohen	thanks ohpauleez. nope, the repl comes up just fine if i'm not in the project dir
18:22	ohpauleez	overstood: If you needed different functions to test for different things
18:23	ohpauleez	overstood: If you're looking for equality, dispatching via maps is usually used
18:23	ohpauleez	(a dispatch table)
18:23	ohpauleez	mcohen: There's an error in the source files you've written
18:23	ohpauleez	try creating a new project with lein2 new, cd into it, and try `lein repl`
18:23	mcohen	ok, but all i did was "lein new appname"
18:24	mcohen	and then lein test
18:24	mcohen	i didn't edit anything
18:24	ohpauleez	there are no tests to run
18:25	overstood	so the map is basically just a bit more concise and faster than cond/case?
18:25	mcohen	test/<project_name>/core_test.clj
18:25	mcohen	is created when i did lein new app
18:25	ohpauleez	more concise and preferred in that case (if you're just checking for equality). I'm not sure about performance
18:26	ohpauleez	mcohen: And what's in that file?
18:26	overstood	ohpauleez: got it, thanks
18:26	mcohen	(ns congo.core-test
18:26	mcohen	(:use clojure.test
18:26	mcohen	congo.core))
18:26	ohpauleez	overstood: No problem!
18:26	mcohen	(deftest a-test
18:26	mcohen	(testing "FIXME, I fail."
18:26	mcohen	(is (= 0 1))))
18:26	ohpauleez	mcohen: try creating a new project and see if the errors happen in the new project
18:27	mcohen	yeah, i tried that already actually.
18:27	mcohen	when i run with the DEBUG flag on it prints Classpath: /Users/mcohen/.lein/self-installs/leiningen-2.0.0-preview7-standalone.jar
18:27	mcohen	but if i run lein classpath, i get
18:28	overstood	one more question, are there any good resources to learn more about performance in clojure. I'm specifically interested in memory allocation. I want to try writing a little game for Android which means I want to try to avoid GC collection if I can.
18:29	dnolen	overstood: Clojure's design assumes GC, it's pretty hard to avoid
18:30	overstood	Even more specifically, when I'm using Clojure functions that don't have side effects. What is allocated and when is it released?
18:32	amalloy	overstood: consider a simple case where x is the list (1 2 3)
18:32	amalloy	if you compute (cons 4 (rest x)), you get back (4 2 3). that list shares the 2 and 3 elements (and the list pointers linking them together) with the original
18:33	amalloy	so the head of the x list is no longer needed (assuming you don't have a reference to x anymore), and it's thrown away, GCed whenever the JVM finds it convenient
18:35	stain	anyone played with the framebuffer (/dev/fb0) from Clojure?
18:35	mcohen	so if you run lein <command> in the root of your clojure project with DEBUG=1 what will be shown as the Classpath variable?
18:36	mcohen	or, what should be shown?
18:36	mcohen	all i see is /Users/mcohen/.lein/self-installs/leiningen-2.0.0-preview7-standalone.jar
18:36	mcohen	but if i run lein classpath then it does in fact list out the jars i've included as dependencies
18:36	mcohen	as well as the src, test, resources, dev-resources, and classes dirs
18:37	mcohen	but the ClassNotFoundException feels like i must have a classpath issue somewhere
18:38	overstood	amalloy: That makes parfect sense. I'm still trying to get an intuitive grasp of the implications of immutable state. Thanks!
18:52	casperc	hello
18:52	casperc	I have this question which is not really clojure specific, but I thought you might be able to help anyway
18:53	casperc	I want to start a clojure process which starts an embedded jetty server at a random port. Then I want to have that port returned to my so I can run som tests against my api
18:53	casperc	anyone know how to go about this?
18:54	jeremyheiler	,(rand-int 100)
18:54	clojurebot	24
18:55	jeremyheiler	casperc: you can also check out the ring-jetty-adapter to see how it starts a jetty server.
18:55	jeremyheiler	https://github.com/mmcgrana/ring/blob/master/ring-jetty-adapter/src/ring/adapter/jetty.clj
18:55	casperc	I want to do this to be able do some cucumber/soapui tests against the api as part of ci
18:56	stain	casperc: ring can do that
18:56	stain	I just type "lein ring server" and it pops up a browser window
18:56	casperc	jeremyheiler: i should clarify, I know how to start the jetty at a random port. What I don't know is how to get that random port returned to the rake script starting the process
18:56	stain	I think it just tries to bind to port 3000, if it is taken, add 1, etc
18:57	jeremyheiler	casperc: how are you invoking the process?
18:57	jeremyheiler	better yet, how do you want to invoke the process? at a repl?
18:58	casperc	doesn't really matter actually, the imortant bit is that the jetty server is started and the port returned so I can run api tests again it externally
18:59	casperc	multiple tests and builds might be running at the same time, so it can't be the same port always
19:01	casperc	actually, come to think of it, the correct way may by for the invocing process to supply the port, not the clojure process to return it
19:02	jeremyheiler	something like this? (let [port (random-port)] (start-jetty-server port) port) which would then return the port number taht you can write to std out or whatever you need to put it.
19:04	casperc	jeremyheiler: that might work
19:05	casperc	I think i will try it the other way around though and have the script starting the process supply the port. Thanks for the input :)
19:05	jeremyheiler	casperc: no problem. good luck
19:06	casperc	thank you
19:14	AWizzArd	Hmm, interesting: at runtime I load a file. This file contains key/value pairs. I now want to implement a macro (with-file "c:/my.file" body). I want that with-file is like an implicit let, where the bindings represent those key/value pairs, so that I can refer to them in the body.
19:15	AWizzArd	Example: in the file I have this map: {:a 1, :b 2, :c 3}. Now I want that (with-file "c:/my.map" (= c (+ a b))) expands to code that will eval to “true” at runtime. I think this could be a case for valid use of “eval”. Opinions?
19:16	nDuff	AWizzArd: Err. Do you want the file to be read at compile time or runtime?
19:16	nDuff	AWizzArd: ...keeping in mind that macro expansion happens at compile time...
19:17	AWizzArd	I want to read the file at runtime.
19:17	nDuff	AWizzArd: ...what you want can't be done without forcing the code within the macro to be recompiled every time it's executed. That's pretty evil.
19:18	nDuff	AWizzArd: is it really _that_ much harder to put the read contents of the file in a variable and refer to (:a my-var) rather than just "a"?
19:18	AWizzArd	nDuff: yes
19:18	AWizzArd	That’s why Clojure offers destructuring.
19:19	AWizzArd	I want runtime destructuring of files.
19:19	nDuff	...sure, but destructuring as it's typically done doesn't impact runtime performance, at least not to the scale you're talking about here; it's a very different tradeoff.
19:19	amalloy	AWizzArd: no, you want destructuring with unknown keys
19:20	amalloy	ignore the "file" part of this entirely - then you're asking for (with-map m body), where body is evaluated with all the locals in m implicitly bound
19:20	AWizzArd	Yes.
19:20	amalloy	which is totally possible and not even hard, but pretty disastrous as an idea
19:20	nDuff	...even though the code may not even _compile_ if the file doesn't contain the keys it needs/expects.
19:21	AWizzArd	amalloy: not hard… without using eval?
19:21	nDuff	Actually -- this is silly. Your code knows which keys it needs.
19:21	amalloy	no, you of course have to use eval
19:21	AWizzArd	Yes, I agree.
19:21	nDuff	So, you can just assume that those keys will be present in the file, and use _real_ destructuring.
19:22	AWizzArd	amalloy: Pretty trivial, just wanted to check if I might have missed something to make this happen without eval.
19:22	nDuff	("real", meaning compile-time)
19:22	amalloy	read over http://stackoverflow.com/questions/9345056/in-clojure-how-to-destructure-all-the-keys-of-a-map before you really commit to doing something that i think is a mistake
19:23	nDuff	AWizzArd: Why can't you use real, fixed-key destructuring, with the set of keys that map to what the code uses?
19:23	nDuff	AWizzArd: After all, you aren't proposing that the code changes, only that the file does.
19:23	AWizzArd	Well, I have nearly 10 years Lisp experience, and I am aware of the multitude of problems.
19:24	nDuff	AWizzArd: ...so there's quite literally no point at all to the extra pain you're wanting to create.
19:25	AWizzArd	nDuff: The whole purpose is to not have to manually extract those keys.
19:25	AWizzArd	It is a pure convenience importer macro.
19:25	nDuff	AWizzArd: not to extract them from the code, as opposed to from the file, right?
19:25	AWizzArd	For FXML files ==> JavaFX
19:25	nDuff	AWizzArd: So you can just have your macro analyze the code at compile time; done.
19:25	amalloy	oh god
19:25	AWizzArd	Yes?
19:25	clojurebot	yes isn't is
19:25	amalloy	that's even worse, nDuff
19:26	Raynes	I think the point amalloy is trying to make is that this is a convenience to you and a terrible, terrible inconvenience to anyone who ever reads your code or works with it, including future you.
19:26	Raynes	You don't want this. Stop before it is too late.
19:26	amalloy	shrug we put up the signposts, he disagrees, and the language gives him a way to do it
19:26	AWizzArd	Plus I think it may turn out useful.
19:27	amalloy	nod if you're doing it as a general-purpose macro where you don't know what the code is or what the config file contains, that's interesting. still has problems, but isn't obviously loony
19:27	AWizzArd	Well, I read a fxml file, and get a hashmap. The keys are keywords, and the values are JavaFX components.
19:28	amalloy	keywords? if they're supposed to represent symbols, and you're reading the file rather than eval'ing it, it makes more sense to store symbols as keys
19:29	AWizzArd	I am really saving a (let [username-label (:username-label fxml), password-label (:password-label fxml), username-text (:username-text fxml) …)
19:29	AWizzArd	A bigger program with several UIs would require always a 20 line let in the setup functions. This can be reduced to a one-liner.
19:30	AWizzArd	(with-fxml ["login-ui" "email-ui"] body)
19:31	AWizzArd	This is actually nicer than a 21 line let.
19:31	AWizzArd	But yes, if this turns out to be too problematic, I will remove it before a 1.0.
19:33	AWizzArd	Also that macro can type-hint all those symbols, so calling into .methods will do no reflection. Type hints are really required, since the UI thread should not be slowed down from reflection.
19:41	AWizzArd	Trivial, thanks to Clojure’s power: (mapcat (fn [[k v]] [(with-meta (symbol (name k)) {:tag (class v)}) v]) my-map)
19:48	amalloy	uhhhhh, is that going to work? it's hard to imagine values for v where the class can be usefully typehinted and the value can be embedded into code
19:50	AWizzArd	The values are Buttons, Labels, TextFields, etc.
19:51	amalloy	i don't think you'll be able to embed those in code
19:51	AWizzArd	And in the body one wants to do things such as (.setText password "").
19:52	amalloy	try it: (defmacro let-button [& body] `(let [~'button ~(make-button-object)] ~@body))
19:52	AWizzArd	Useful when we get a (let [^PasswordField password (:password fxml)] …)
19:53	AWizzArd	instead of ~'button it should probably be something like ~(with-meta 'button {:tag Button})
19:53	amalloy	AWizzArd: yes, but that's not relevant to my objection
19:53	AWizzArd	Then I don’t understand it yet. Could you say it in other words?
19:55	amalloy	AWizzArd: either v is a Button object, or it's code that you could evaluate to produce a Button
19:55	amalloy	if the former, then you can't embed it as part of the let statement
19:55	amalloy	if the latter, you won't have its class yet
19:56	amalloy	also, you want {:tag `Button}, not {:tag Button}; tags are symbols, not classes
19:57	AWizzArd	Yes, it was just a sketch.
19:57	AWizzArd	I will experiment with this now.
20:01	AWizzArd	amalloy: I can go around this by not taking the (class v) but (class (eval v)).
20:01	AWizzArd	The interesting thing here is though that the symbols that end up in the body, are different from the ones in the let.
20:02	amalloy	i don't understand that last
20:03	AWizzArd	amalloy: try this: (defmacro bar [m & body] (let [lala (mapcat (fn [[k v]] [(with-meta (symbol (name k)) {:tag (class (eval v))}) v]) m)] `(let [~@lala] ~@body)))
20:04	AWizzArd	amalloy: then in the repl: (def x (macroexpand '(bar {foo (:lup {:lup "Hi"})} (.length foo))))
20:05	AWizzArd	(-> x second first meta) ==> String, but (-> x last last meta) ==> nil
20:05	amalloy	of course
20:05	AWizzArd	Although when you try both -> forms without the last meta, you will both times see it is foo.
20:05	amalloy	just like without a macro
20:05	AWizzArd	But also that can be solved :-)
20:05	amalloy	what? don't solve it
20:05	amalloy	it's not a problem
20:06	AWizzArd	Why not? I want those type hints.
20:06	amalloy	no you don't
20:06	amalloy	(let [^Foo x 1] x) - nobody writes (let [^Foo x 1] ^Foo x), because there's no reason
20:06	AWizzArd	Turn on reflection warnings, and you will see that (bar {foo (:lup {:lup "Hi"})} (.length foo)) throws a warning.
20:07	AWizzArd	I want that the vars in the body inherit the type hints from the let.
20:07	AWizzArd	So I need the identical (hinted) symbols in the body.
20:07	amalloy	no you don't
20:07	amalloy	they always inherit
20:07	amalloy	the problem is still what i said: tags are symbols, not classes, and you're trying to use a class
20:08	AWizzArd	Ah, right.
20:08	AWizzArd	Good point.
20:09	AWizzArd	Yes, works.
20:10	AWizzArd	Lot’s of evals, but currently I still think this is a valid use case for it. I am thankful for the scepticism to use it, but I want to remind that I am the guy who invented scepticism against the use of eval.
20:11	amalloy	shit, really? i thought you were dead, mister mccarthy
20:11	AWizzArd	;)
20:12	AWizzArd	In fact, so far my only real usecase for it was my Genetic Programming lib, where it is obviously the right choice.
20:12	AWizzArd	(as the whole point is the creation of code at runtime, and then run it)
20:40	dyba	Should I be expecting an OutOfMemoryError when using (range) ?
20:40	dyba	I understand (range) creates a lazy sequence from 0 to positive infinity
20:40	AWizzArd	Fortunately range is lazy, as you said.
20:40	dyba	but I guess I don't quite understand what lazy means
20:40	AWizzArd	So it will only produce those numbers when they are needed.
20:41	dyba	so I shouldn't be expecting an out of memory error, correct?
20:41	AWizzArd	Yes.
20:41	AWizzArd	Just don’t keep a pointer to the begin of the sequence.
20:41	dyba	the only string i get explaining the error is Java heap space
20:42	dyba	my test is currently failing
20:42	AWizzArd	(doseq [n (range)] (when (= n 9999999999999) (System/exit 0))) will run fine, without killing the RAM. It would run a long time though.
20:43	dyba	AWizzArd: I was just running a simple test to make sure I understand what to expect from using range
20:43	dyba	inside a test I wrote:
20:43	dyba	(is (= 0 (range)))
20:44	dyba	but that's not quite correct, it should fail
20:44	dyba	but i got a failure for a different reason, i.e. OutOfMemory
20:44	dyba	AWizzArd: so would your approach be a better way to test what I had in mind?
20:47	AWizzArd	Well, (range) is a sequence of numbers.
20:47	AWizzArd	The 0 is one of them.
20:47	AWizzArd	But “a sequence of numbers” is not equal to the number zero.
20:48	AWizzArd	But (is (= 0 (first (range)))) should succeed.
20:48	dyba	right
20:49	ToxicFrog	<dyba> but I guess I don't quite understand what lazy means - lazy seqs evaluate each element only as needed. (take 5 (range)) evaluates only the first five elements in the seq, even though the seq is, in principle, infinite.
20:50	AWizzArd	amalloy: it is in fact very exciting how easy this is in Clojure. Java developers who want to work with FXML will have to manually extract all their components which they want to refer to in event handlers.
20:50	AWizzArd	That option is still available in my lib, and it also has advantages. But being able to automtically import them is a very nice feature.
20:50	dyba	ToxicFrog: so (range) shouldn't return anything because I haven't carried out any operations on it?
20:50	ToxicFrog	Depends on what you do with it
20:51	ToxicFrog	(= 0 (range)) might actually evaluate the entire sequence as it tries to do the compare.
20:51	dyba	ah I see, hence the OutOfMemory error
20:52	aamar	dyba: it also might be the clojure.test framework creating the error, as it tries to inform you why the equality comparison failed.
20:53	ToxicFrog	Yeah, in that case it might try to evaluate the seq so that it can print it or something.
20:53	ToxicFrog	And then boom.
20:53	dyba	aamar: I believe you are right, I would have to see what = is doing under the covers
20:53	aamar	I suspect it's that, because (if (= 0 (range)) 1 2) works fine for me
20:53	ToxicFrog	Alright then
20:54	AWizzArd	,(= 0 (range)) ; = does not traverse the whole range
20:54	clojurebot	false
20:55	dyba	thanks <ToxicFrog>, <aamar>, <AWizzArd>!
20:56	dyba	oh so it's probably the 'is' in the testing clojure.test framework
20:57	AWizzArd	That may be it.
20:58	AWizzArd	Though I would find that a bit surprising.
21:08	dyba	range doesn't look like it's capable of handling floats correctly, am I correct?
21:08	AWizzArd	What means “handling floats”?
21:08	dyba	I just tried (range 1.0 2.0 0.2) and it didn't quit get to 1.6
21:08	dyba	it gave me 1.5999999
21:09	dyba	it gave me (1.0 1.2 1.4 1.59999... 1.79999... 1.99999...)
21:09	AWizzArd	dyba: You would like to read http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html
21:10	AWizzArd	“What Every Computer Scientist Should Know About Floating-Point Arithmetic”
21:10	dyba	AWizzArd: will do, I'll check it out right now
21:10	AWizzArd	It is a pretty long read, but important stuff in there.
21:11	AWizzArd	,(range 1 2 1/5)
21:11	clojurebot	(1 6/5 7/5 8/5 9/5)
21:11	dyba	AWizzArd: Ah ha! you used a rational
21:11	dyba	I forgot about those in Clojure
21:12	AWizzArd	Although 1.5999999 is as close as you can get to 1.6, when you just can express 4 billion different numbers (i.e. floats).
21:13	AWizzArd	You have only 2^32 numbers available (4 billion), as floats have to encode those numbers in 32 bits.
21:17	Frozenlock	Is there some mechanism to install and auto-run a clojure app at each reboot? (Or is this more of a java question?)
21:18	AWizzArd	dyba: the engineers who implemented this had a pretty hard job. Out of all numbers they had to choose 4 billion that can be expressed with a float. Obviously nearly all numbers had to be excluded. They concentrated on numbers that are typically interesting to scientists.
21:18	AWizzArd	Frozenlock: more a question of your operating system.
21:19	Frozenlock	True. Let's say a windows machine. I already use launch4j to wrap my jars, but I would like a proper installation.
21:19	AWizzArd	dyba: what you can do though is not using the floating-point unit that ships with your mainboard, but instead use a java.math.BigDecimal, which has a different representation and allows for much more precision.
21:20	AWizzArd	dyba: in Clojure there is even a reader syntax for such numbers. Just append an uppercase “M”:
21:20	AWizzArd	,(range 1.0M 2.0M 0.2M)
21:20	clojurebot	(1.0M 1.2M 1.4M 1.6M 1.8M)
21:22	AWizzArd	Frozenlock: this is a not so trivial issue and has not really to do with Clojure or Java. You should try in #Windows. If you know about Windows Services you might be interested in http://yajsw.sourceforge.net/
21:22	AWizzArd	Frozenlock: it will probably take you 3-15 hours to get this working.
21:22	Frozenlock	Hmmmm so adding the Frozenlock effect, I should count 48 hours :P
21:23	Frozenlock	Thanks, I'll take a look!
21:23	AWizzArd	But a very simple way would be to run a .bat file on reboot. In that file you have a line such as: start java -jar c:/users/frozenlock/Desktop/nice-tool.jar
21:24	AWizzArd	That’s a fast and nice way for small admin UIs and such. But professional server software should really run as a Service.
21:24	Frozenlock	Yeah it does sound hacky- but for a proof of concept it might be enough. Thank you very much!
21:27	dyba	AWizzArd: I'll look into that, thanks!
21:32	ToxicFrog	God, I hate deploying on windows.
21:38	dyba	ToxicFrog: are you doing that for work?
21:40	ToxicFrog	dyba: no, but one of my current projects is designed to integrate with a game released on windows and OSX
21:40	ToxicFrog	So it needs to work on windows
21:49	dyba	AWizzard: yup, the BigDecimal instance works better for the use case I had brought up
22:01	evildaemon	I'm not quite sure I understand the "lists" model of data processing.
22:01	evildaemon	I know all the data structures are immutable. But I'm not sure how to build new lists out of the old ones.
22:04	evildaemon	As an example, if I try to use conj to build a new list, I get a list bubble and then the contents of the other list.
22:04	evildaemon	Cons does the same thing.
22:04	ToxicFrog	How are you using them?
22:04	ToxicFrog	,(cons 1 '(2 3 4))
22:04	clojurebot	(1 2 3 4)
22:05	evildaemon	ToxicFrog: Thank you.
22:05	ToxicFrog	,(cons '(2 3 4) 1)
22:05	clojurebot	#<IllegalArgumentException java.lang.IllegalArgumentException: Don't know how to create ISeq from: java.lang.Long>
22:05	ToxicFrog	Whups
22:05	ToxicFrog	,(cons '(2 3 4) '(1))
22:05	clojurebot	((2 3 4) 1)
22:05	evildaemon	lol.
22:06	evildaemon	Wait, isn't it kind of dangerous to have a clojure interpreter just sitting in the IRC channel?
22:07	ToxicFrog	Pretty sure it's sandboxed so that you can't actually damage anything
22:07	ToxicFrog	,(println (range))
22:07	clojurebot	(0 1 2 3 4 ...)
22:07	ToxicFrog	,(dorun (map println (range)))
22:07	clojurebot	Execution Timed Out
22:08	evildaemon	ToxicFrog: I suspected as much, couldn't see how the channel wouldn't be spammed to death by recursive functions otherwise.
22:09	ToxicFrog	,(dorun (map println (range 1 100)))
22:09	clojurebot	1
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22:09	ToxicFrog	Oh god
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22:10	ToxicFrog	I'm so sorry
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22:10	ToxicFrog	I should have PMd that
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22:10	TheBusby	nice, like times of old
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22:10	ToxicFrog	evildaemon: it's not nearly as well sandboxed as I thought :/
22:10	clojurebot	41
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22:10	ToxicFrog	Also, I should have tested with (range 1 5)
22:10	clojurebot	58
22:10	evildaemon	Goddamit.
22:10	clojurebot	59
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22:11	Frozenlock	That's funny
22:11	clojurebot	68
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22:11	Frozenlock	Isn't there a time limit for clojurebot?
22:11	clojurebot	77
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22:11	evildaemon	I'm sorry I said anything.
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22:11	ToxicFrog	Feature request for clojurebot: combine multiple lines of output into single IRC message; restrict the number of messages a single command can emit.
22:11	evildaemon	Yes.
22:12	Frozenlock	At least now we know.
22:12	evildaemon	What? No one ever tried that before?
22:12	TheBusby	an knowing is half the battle?
22:13	Frozenlock	Yup, now we know who the enemy is :)
22:13	Frozenlock	,flame ToxicFrog
22:13	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve symbol: flame in this context, compiling:(NO_SOURCE_PATH:0)>
22:13	Frozenlock	What, no flame bot?
22:14	ToxicFrog	Frozenlock: there is a time limit, but apparently that didn't hit it!
22:14	evildaemon	(defn 787 (print 5))
22:14	evildaemon	,(defn 787 (print 5))
22:14	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Parameter declaration print should be a vector>
22:15	evildaemon	Oh right, arguments.
22:15	Frozenlock	I think defn is forbidden as a protection
22:15	Frozenlock	Isn't it?
22:15	evildaemon	(defn 787 [] (print 5))
22:15	evildaemon	,(defn 787 [] (print 5))
22:15	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.ClassCastException: java.lang.Long cannot be cast to clojure.lang.IObj>
22:15	ToxicFrog	,(defn foo [x] (println x)) (foo 1)
22:15	clojurebot	#<Exception java.lang.Exception: SANBOX DENIED>
22:15	ToxicFrog	Yep.
22:15	evildaemon	Ah.
22:15	ToxicFrog	SANBOX.
22:15	evildaemon	Interesting.
22:16	evildaemon	So I would assume that def and fn are blocked as well?
22:16	Frozenlock	Hopefully
22:20	evildaemon	,(def test556 9)
22:20	clojurebot	#<Exception java.lang.Exception: SANBOX DENIED>
22:20	Frozenlock	, (map (fn [a] (print a)) [1 2 3 4])
22:20	clojurebot	(1234nil nil nil nil)
22:20	Frozenlock	wut
22:21	evildaemon	lol.
22:21	Frozenlock	It does the same thing on my repl....
22:21	Frozenlock	What am I missing here
22:21	evildaemon	Oh dear.
22:22	Frozenlock	, (map (fn [a] a) [1 2 3 4])
22:22	clojurebot	(1 2 3 4)
22:23	Frozenlock	Oh I see... Print send them to out (which is the repl), the return nil for everyone of them.
22:23	Frozenlock	*then
22:24	evildaemon	I love how the last github commit is entitled: "Should have thought this through."
22:24	arohner	is there a library like trammel that can be used to provide "inheritance" for fn contracts?
22:25	Frozenlock	evildaemon: Funny, but kinda lack precision
22:25	arohner	I'd really like to define a contract for a class of fns, and then define new fns, that match the same contract
22:26	arohner	and it'd be amazing if at least part of it was verified at compile time
22:41	evildaemon	,(print "(+ 2 2)")
22:41	clojurebot	(+ 2 2)
22:42	evildaemon	,(print ",(+ 2 2)")
22:42	clojurebot	,(+ 2 2)
22:47	Frozenlock	Ok I'm doing it, jumping to lein 2 and clojure 1.4, wish me luck!
22:48	evildaemon	ToxicFrog: How do I do that with named lists?
22:49	ToxicFrog	evhan: "named lists"?
22:50	evildaemon	ToxicFrog: You know, lists that have symbols attached with def or let.)
22:50	ToxicFrog	Er
22:50	tos9	evildaemon: I checked that :)
22:50	tos9	evildaemon: It's amazing how many bots are vulnerable to that sort of exploit.
22:51	ToxicFrog	evildaemon: you're going to have to explain in more detail what you're trying to ask
22:52	evildaemon	tos9: I didn't feel like pushing it, but I briefly thought: "I wonder if I look at the source I'll discover that trick will work if you append a users name and timestamp before it."
22:53	evildaemon	ToxicFrog: (def r (list 7 7 6 5 0))
22:53	evildaemon	Not sure what it's actually called.
22:53	ToxicFrog	Ok, in that case, what is the "that" that you want to do?
22:57	evildaemon	ToxicFrog: This could take while.
22:58	ToxicFrog	evildaemon: I mean, it looks like you're asking "how do I print a list by name" but that's the same as anything else - (def r '(1 2 3 4 5)) (println r)
22:58	ToxicFrog	So you must be asking something else
22:59	evildaemon	ToxicFrog: How do I combine two lists?
23:00	mindbender	anyone using counterclockwise here?
23:01	ToxicFrog	evildaemon: depends on what you mean by "combine", but probably (concat xs ys)
23:01	ToxicFrog	,(concat '(1 2 3) '(4 5 6))
23:01	clojurebot	(1 2 3 4 5 ...)
23:01	ToxicFrog	evildaemon: also, it sounds like you need this: http://clojure.org/cheatsheet
23:01	ToxicFrog	It is damn useful.
23:02	evildaemon	ToxicFrog: Yes.
23:37	mindbender	with counterclockwise I'm having trouble importing a github project, need I install git for eclipse
23:37	mindbender	?
23:41	acristin	mindbender: I haven't installed git for eclipse, and I have been able to import github projects that I had cloned through the git commandline tool, but I think eclipse copied the whole directory into my workspace. I'm not sold on counterclockwise yet, so I didn't really try very hard
23:44	mindbender	acristin: ok.. I'm still exploring too and wondering why it won't even recognize my cloned repo in the first place but I'm corresponding with Laurent, a top maintainer of ccw, thanks for sharing your experience!
23:53	ssutch	is it possible to def a function that can respond differently to different keyword arguments, eg
23:54	ssutch	,(defn a ([{a1 :a1}] ("something")) ([{a2 :a2}] ("something else"))
23:54	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
23:54	ssutch	,(defn a ([{a1 :a1}] ("something")) ([{a2 :a2}] ("something else")))
23:54	clojurebot	#<Exception java.lang.Exception: SANBOX DENIED>
23:54	ssutch	bajh
23:55	ssutch	"cant have 2 overloads with the same arity" is what it should print