#clojure – 2011-06-12

2011-06-12

01:09	grantm	Say I want to do (new java.awt.Color my-list) where my-list is (255 0 0), so that I get (new java.awt.Color 255 0 0) in the end. The web says generally the right way is to use apply, but I can't seem to get it to work here (it gives a strange error). How do I do what I want?
01:10	tomoj	first, (java.awt.Color. 255 0 0) is more idiomatic (just some syntax sugar for what you wrote)
01:10	tomoj	&(apply #(java.awt.Color. %1 %2 %3) [255 0 0])
01:10	sexpbot	⟹ #<Color java.awt.Color[r=255,g=0,b=0]>
01:11	tomoj	ugly, but works
01:11	tomoj	you can't apply 'new' or constructors since they're not actually functions, but you can create a function that just calls the constructor and apply it
01:13	tomoj	&(letfn [(color [[r g b]] (java.awt.Color. r g b))] (color [255 0 0]))
01:13	sexpbot	⟹ #<Color java.awt.Color[r=255,g=0,b=0]>
01:13	tomoj	something like that could work too
01:17	grantm	thanks a lot! but all these ways seem to hardcode the number of arguments. is there a general way to not do that? (i guess you could build a macro for it?)
02:42	Scriptor`	hi everyone
11:56	mudge	hello
11:56	mudge	what is an "associative collection" ?
11:57	mudge	what does it mean if a data type is associative?
12:03	mudge	anybody here today?
12:07	mudge	hey halfprogrammer
12:07	mudge	hey, how do I found out if a value is a sequence or not?
12:07	halfprogrammer	Hi
12:08	halfprogrammer	(seq? BLAH)
12:09	halfprogrammer	mudge: when you say seq, among collections (list, vecotrs, map and set) (seq? X) returns true only for list
12:09	halfprogrammer	,(seq? [1])
12:09	clojurebot	false
12:10	halfprogrammer	mudge: If you are interested in getting true for the rest of the collection types too then use coll?
12:10	halfprogrammer	,(coll? [])
12:10	clojurebot	true
12:11	mudge	thanks halfprogrammer
12:11	TimMc	mudge: Associative means there are key-value pairs.
12:12	mudge	TimMc: oh, okay, thanks
12:12	mudge	that explains it
12:12	TimMc	Maps (dicts in other languages) are the classic example.
12:12	mudge	TimMc so vectors are also associative then, because vectors have numeric indexes
12:12	TimMc	You might be able to call vectors associative (treating indices as keys) but that might be a stretch.
12:13	mudge	yea!
12:13	TimMc	I think not, though -- maps are primarily accessed by key, not by ordering.
12:13	TimMc	What's the context?
12:13	mudge	TimMc even sets could be considered associative because in a set the key of a value is the value
12:13	TimMc	That's more of a hack, really. :-P
12:14	mudge	yea
12:14	mudge	i am reading somewhere that says that all collections can be treated as sequences
12:14	mudge	so I am wondering why all collections are not sequences if they can be treated as sequences
12:15	mudge	so a map can be treated as a sequence?
12:15	TimMc	mudge: Sure!
12:15	mudge	wow, neat
12:16	TimMc	,(map identity {:a 5, :b 6})
12:16	clojurebot	([:a 5] [:b 6])
12:16	TimMc	,(type (first {:a 5, :b 6}))
12:16	clojurebot	clojure.lang.MapEntry
12:16	halfprogrammer	mudge: as TimMc said don't rely on ordering of sets and maps
12:16	mudge	then why are all collections not sequences?
12:16	halfprogrammer	,(sequential? {})
12:16	clojurebot	false
12:16	TimMc	mudge: It's the other way around -- sequences are collections
12:17	TimMc	,(coll? (seq '(1 2 3 4)))
12:17	clojurebot	true
12:17	mudge	TimMc, yes I see that
12:17	mudge	but if all sequence functions can work on maps then why aren't maps sequences?
12:17	__name__	,(map #(* % 2) {1 2 3 4})
12:17	clojurebot	java.lang.ClassCastException: clojure.lang.MapEntry cannot be cast to java.lang.Number
12:18	__name__	,(map #(%) {1 2 3 4})
12:18	clojurebot	java.lang.IllegalArgumentException: Wrong number of args (0) passed to: MapEntry
12:18	mudge	like duck typing, if it walks like a duck and quacks like a duck then it is a duck ----- so why aren't maps sequences if they sequence like a sequence?
12:18	__name__	,(map (fn [x] x) {1 2 3 4})
12:18	clojurebot	([1 2] [3 4])
12:19	halfprogrammer	I think we use the term sequence if there is a well defined order of iteration
12:19	halfprogrammer	that is why vectors and lists are sequential
12:19	halfprogrammer	i mean (sequential? vec-or-lst) returns true
12:19	__name__	,(map (juxt first #(* 2 (second %)) {1 2 3 4})
12:19	clojurebot	EOF while reading
12:19	__name__	,(map (juxt first #(* 2 (second %)) {1 2 3 4}))
12:19	clojurebot	java.lang.IllegalArgumentException: Wrong number of args (1) passed to: core$map
12:20	__name__	,(map (juxt first #(* 2 (second %))) {1 2 3 4})
12:20	clojurebot	([1 4] [3 8])
12:20	mudge	(seq '[4 5])
12:20	mudge	,(seq '[3 4])
12:20	clojurebot	(3 4)
12:20	mudge	,(seq? '[3 4])
12:20	clojurebot	false
12:21	mudge	halfprogrammer: a vector is not a sequence
12:21	__name__	What's it with quoting the vector?
12:21	halfprogrammer	,(sequential? [3 4])
12:21	clojurebot	true
12:21	__name__	That does not really make sense.
12:21	__name__	,(seq [3 4])
12:21	clojurebot	(3 4)
12:21	mudge	halfprogrammer, try using seq?
12:21	halfprogrammer	seq? returns true for lazy sequences, I think
12:22	thorwil	hmm, using (defmulti valid-item-range #(nil? %)) things work as expected, but would be more readable in inversion. (defmulti valid-item-range #(not (nil? %))) and flipping true/false on the methods does not work here 0.o
12:26	TimMc	mudge: but a vector is Seqable
12:27	TimMc	That is, it supports taking (seq) of it.
12:27	mudge	Okay, but why is a map not a sequence if all the sequence functions work on it?
12:28	TimMc	mudge: (first) calls (seq) on its argument.
12:28	mudge	TimMc --- I seeeeee, so a map doesn't support the sequence functions until seq is called on it
12:29	TimMc	,(type (seq {}))
12:29	clojurebot	nil
12:29	TimMc	,(type (seq {:a "not empty"}))
12:29	clojurebot	clojure.lang.PersistentArrayMap$Seq
12:29	__name__	,(seq {:a :foo})
12:29	clojurebot	([:a :foo])
12:29	TimMc	,(type {:a "not empty"})
12:29	clojurebot	clojure.lang.PersistentArrayMap
12:29	TimMc	You get back a lightweight iterator over the map, basically.
12:30	mudge	TimMc: i see, thanks
12:30	TimMc	Now that I tihnk about it, that's one of the things that tripped me up at the beginning too.
12:31	TimMc	mudge: NOw reread http://clojure.org/sequences -- it will probably make more sense.
12:31	mudge	TimMc: okay, thanks
12:32	TimMc	I have to read the clojure.org pages more than once to really internalize the ideas, and it helps to bang my head against some code in the meantime. :-P
12:33	mudge	TimMc: yea
12:33	mudge	TimMc: do you have clojure stuff on github? i'm curious
12:33	TimMc	yep, though I can't vouch for the idiomatic-ness of it :-)
12:33	halfprogrammer	:P
12:34	TimMc	https://github.com/timmc/CS4300-hw6 <- a ray tracer I made for a computer graphics class
12:34	__name__	neat
12:34	__name__	clojure raytracer
12:34	TimMc	See the README for a link to a better one. :-P
12:34	mudge	cool
12:35	TimMc	I did all my CompGraph assignments in Clojure that semester.
12:35	__name__	It shows how Clojure still scares me :)
12:36	TimMc	Ooh, a github bug!
12:36	TimMc	I have a file with a ? in its name.
12:36	__name__	github is bugged
12:36	__name__	Milestones are garbage.
12:38	TimMc	Try going to either of the first two files in this directory: https://github.com/timmc/CS4300-hw6/tree/master/dev
12:38	TimMc	I sent them a bug report.
12:38	__name__	Haha
12:39	TimMc	mudge: Oh, and you may wonder how ##(seq "foo") works, given that j.l.String doesn't implement Seqable... I suspect protocols are involved.
12:39	sexpbot	⟹ (\f \o \o)
12:40	TimMc	Either that or special-casing.
12:42	mudge	TimMc: since String doesn't implement Seq, it looks like Seq turns the string into a list of characters
12:42	TimMc	Yeah, I'm just wondering how it recognizes it.
12:42	TimMc	hmmm...
12:43	TimMc	,(sequential? "foo")
12:43	clojurebot	false
12:43	mudge	TimMc: maybe it recognizes it by checking to see if it is a String type
12:43	TimMc	OK, so there's ISeq, Iterable...
12:44	TimMc	and I still don't know the difference between seq? and sequential?...
12:46	mudge	TimMc: me either
12:50	__name__	,iterable?
12:50	clojurebot	java.lang.Exception: Unable to resolve symbol: iterable? in this context
12:51	mrBliss`	seq? is true when the argument is a sequence (generated by a seq call on something non empty). sequential? is true when calling seq on the argument would result in something for which seq? is true (unless it's empty).
12:52	mudge	mrBliss, thanks, where did you find that out?
12:53	tomoj	&((juxt sequential? (comp seq? seq)) {1 2})
12:53	sexpbot	⟹ [false true]
12:54	TimMc	mrBliss`: Not for strings.
12:54	mrBliss`	mudge: read the source
12:54	TimMc	,(seq? (seq "foo"))
12:54	clojurebot	true
12:54	TimMc	,(sequential? "foo")
12:54	clojurebot	false
12:55	mrBliss`	TimMc: Yeah, it's not actually 100% correct, but in general (for [], {}, #{}...) it is ;-)
12:55	tomoj	not maps, see above
12:55	TimMc	well, yeah...
12:55	tomoj	&((juxt sequential? (comp seq? seq)) #{1 2})
12:55	sexpbot	⟹ [false true]
12:55	tomoj	not sets either
12:56	mudge	&(+ 4 5)
12:56	sexpbot	⟹ 9
12:56	halfprogrammer	interesting, I am looking at gvec.clj in clojure source file and apparently there is method for sequential. "clojure.lang.Sequential ;marker, no methods"
12:56	mrBliss`	tomoj: Ok, nvm :-)
12:57	tomoj	sequential does not mean seqable
12:57	mrBliss`	https://gist.github.com/950144/51f669b6b62c386330e63071e8870853b0607acf
12:57	tomoj	didn't someone make a nice chart?
12:59	halfprogrammer	mrBliss`: nice
12:59	thorwil	why does what i thought would be a simple boolean flip not lead to equivalent results: http://paste.pocoo.org/show/405093/ ?
12:59	TimMc	Who is swannodette again?
12:59	grantm	noob question: if i do (defmacro my-apply (func args) (cons func args)), it works if i do like (my-apply + (1 2)) but fails if i do (define x (list 1 2)) (my-apply + x) because it doesn't know how to make a seq from a symbol. how do i let it know?
12:59	mrBliss`	TimMc: dnolen
13:00	TimMc	thanks
13:01	tomoj	grantm: is that clojure?
13:01	grantm	yup
13:01	tomoj	params need to be in vectors, there is no define
13:01	grantm	oh, i meant (def x (list 1 2))
13:01	TimMc	I don't think that's the issue.
13:01	tomoj	(defmacro my-apply (func args) ...) certainly shouldn't work at all
13:01	TimMc	grantm: Run (macroexpand-1 `(my-apply + x))
13:02	TimMc	then look at the cons
13:02	grantm	ah my mistake, i was doing the params list with [], i just copied it wrong
13:02	tomoj	ah
13:03	grantm	i get "don't know how to create ISeq from symbol"
13:03	mudge	why does the reverse function return a list?
13:03	TimMc	grantm: Ah, my bad.
13:03	mudge	&(reverse [3 4 5 6])
13:03	sexpbot	⟹ (6 5 4 3)
13:03	TimMc	Right, put a println in your macro.
13:03	mudge	&(type (reverse [3 4 5 6]))
13:03	sexpbot	⟹ clojure.lang.PersistentList
13:04	thorwil	mudge: maybe it's related to performance characteristics?
13:04	mudge	why does it return a list and not a vector because a vector was supplied as the argument
13:04	TimMc	grantm: Your macro is getting arguments ['+ 'x], not ['+ '(1 2)]
13:04	grantm	right
13:05	TimMc	So I think you want to use ~ to evaluate the second argument into a list.
13:09	TimMc	Hmm, that's not quite right either.
13:09	grantm	TimMc: So the only way I can use ~ is if i'm returning something quoted (right?) I get as far as (defmacro my-apply [func args] `(~func ~@args)), but then when i run it i get the same error.
13:09	halfprogrammer	reverse code: (reduce conj () coll)
13:09	TimMc	grantm: I think apply might actually be a special thing.
13:09	halfprogrammer	Not sure why it is implemented this way...
13:10	grantm	TimMc: Oh, that would be a shame...
13:12	TimMc	grantm: Macros are syntax transformers, and apply actually works with values.
13:13	grantm	TimMc: How can I tell the difference in the future?
13:15	TimMc	I think it's really a rare example.
13:15	manutter	The thing about macros is that they operate on the raw code before it actually executes
13:16	TimMc	Look at it this way... (my-apply + x) wants to take `+ and `x and turn it into (`+ `1 `2) ... but `x->(list 1 2) doesn't exist yet.
13:16	manutter	so if you say (defmacro foo [x] (bar ~x)), and then you call (foo y), the value for ~x evaluates to the symbol y, not the value of y
13:17	grantm	okay, i think that makes sense, thanks!
13:17	manutter	Macro expansion turns (foo y) into (bar y), and then the bar function actually looks to see what the current value of y is
13:17	manutter	the macro-expander never checks the value of y
13:19	TimMc	grantm: The macro expander doesn't even "know" that x is an available var...
13:20	TimMc	that's the job of the implicit syntax-quote that happens when you call a macro.
13:20	TimMc	,`x
13:20	clojurebot	sandbox/x
13:22	tomoj	implicit syntax-quote?
13:25	TimMc	tomoj: Well, when you call a macro, it gets fully resolved names.
13:26	TimMc	It's getting the syntax from the reader, so you can think of it like syntax-quote having been applied to the expression.
13:27	tomoj	is that new in 1.3.0 or something? or maybe I'm just not understanding what you mean
13:27	tomoj	is this not a counterexample: (defmacro foo [x] (namespace x)) (foo +)
13:27	TimMc	hrm
13:27	TimMc	maybe I am wrong!
13:28	TimMc	Blah, I guess I was confusing it with something else.
13:28	TimMc	I should not give advice in here when I have not written Clojure in the past month. >_<
14:12	mDuff	My expectation is that (identical? [:a] [:a]) would be true -- given as a clojure object is immutable, I would expect identical values to share identity -- but this isn't the case. What's the basis of my misunderstanding here?
14:13	pdk	it's probably producing a new vector object for each one
14:14	mDuff	What should I be using instead? I'm trying to find a common way to compare native collections in the API doc and coming up empty.
14:14	dnolen	mDuff: =
14:14	mDuff	ahh; I tried ==, and it complained to me about being numeric-only
14:14	dnolen	,(= [:a] [:a])
14:14	clojurebot	true
14:15	mDuff	thanks!
14:17	TimMc	mDuff: identical? is pointer comparison
14:17	dnolen	what's the best way to check if a class exists? Trying to work around the fact that 1.3.0 has ArityException and 1.2.0 does not.
14:18	TimMc	,(identical? 3 3)
14:18	clojurebot	true
14:18	TimMc	,(identical? 300 300)
14:18	clojurebot	false
14:19	TimMc	dnolen: Reflection?
14:19	TimMc	:-/
14:21	TimMc	If you don't mind try/catch, there's Class/forName
14:22	TimMc	,(Class/forName "ArityException")
14:22	clojurebot	java.lang.ClassNotFoundException: ArityException
14:23	dnolen	TimMc: yeah I saw that
14:23	TimMc	,(Class/forName "String")
14:23	clojurebot	java.lang.ClassNotFoundException: String
14:23	TimMc	,(Class/forName "java.lang.String")
14:24	clojurebot	java.lang.String
14:28	dnolen	works well enough for me.
14:34	TimMc	Make it a wrapper function I suppose?
14:34	TimMc	Also, why do you need to reflect on this?
14:43	dnolen	TimMc: because ArityException doesn't exist in 1.2.0
14:43	dnolen	TimMc: I'm creating a macro to define the appropriate code depending on whether ArityException exists or not.
14:44	fliebel	How would you explain the different attitude towards exceptions in Python and Clojure?
14:44	dnolen	fliebel: in Clojure exceptions are ... exceptional.
14:45	dnolen	fliebel: btw, the desire to make fact not be a macro has created a monstrous amount of macros :)
14:45	fliebel	dnolen: how so?
14:45	dnolen	fliebel: implementing IFn
14:48	fliebel	dnolen: rhickey just nuked this idea, but maybe you could generate a map and pass it to extend.
14:49	dnolen	fliebel: No I don't want any overhead.
14:50	fliebel	dnolen: Do you know if the exception thing is technical or just convention?
14:50	dnolen	fliebel: I remember being surprised at exception-for-flow-control in Python since I hadn't really seen that elsewhere.
14:50	fliebel	( http://jaynes.colorado.edu/PythonIdioms.html#eafp )
14:51	dnolen	I don't really like it.
14:51	TimMc	fliebel: a.k.a. the optimistic approach
14:56	fliebel	TimMc: What do you mean?
14:56	TimMc	fliebel: Assume there won't be an exception, but handle it if there is one.
14:57	fliebel	It seems to be their primary type system.
14:58	TimMc	What does it have to do with their type system>
14:58	fliebel	TimMc: Duck typing, They don't check if something is something, but just try to act as if it where something.
15:00	TimMc	Ah, yeah. That is kind of similar.
15:13	dnolen	400 lines of AFn.java in 48 lines of Clojure, https://gist.github.com/1021886
15:15	dnolen	actually more like 33 when you take out all the core.logic crap
15:18	nickik	dnolen, There is a question on stackoverflow about typesystems in Clojure. I am about to anwer it (you could have one in lisp but clojure doesn't is the short version) but i remember reading that core.logic does have something like that. Is that ture? (I have not looked at core.logic jet)
15:19	dnolen	nickik: you could build something like that with core.logic yes, but I haven't done any work along those lines.
15:36	mudge	Clojure has a single primitive construct "loop"
15:36	mudge	but what is a construct? how is it different than a form?
15:38	dnolen	mudge: it's one of the special forms, http://clojure.org/special_forms
15:38	nickik	mudge, there are just some things that the compiler has to know
15:39	TimMc	mudge: https://github.com/clojure/clojure/blob/1.2.x/src/jvm/clojure/lang/Compiler.java#L37
15:40	nickik	all the special forms are engouth to build the hole language. So if you want to reimplement the hole langauge you would have to build a compiler that just implements all the spezial forms (and a reader).
15:40	TimMc	whole, even
15:41	mudge	but what is the difference between a special form and a construct?
15:41	fliebel	How many special forms does Clojure have? Scheme has 7, right?
15:42	mudge	Clojure also has exactly one primitive control flow construct:loop
15:42	nickik	i think its soemthing like 12
15:43	fliebel	Hm, maybe if we drop Java interop, we can beat Scheme ;)
15:45	Scriptor	do the .net and javascript (if it exists) versions use the same operators reserved for java interop?
15:48	tomoj	special-form-anchor references 16 special forms: #{'. 'def 'do 'fn 'if 'let 'loop 'monitor-enter 'monitor-exit 'new 'quote 'recur 'set! 'throw 'try 'var}
15:50	TimMc	mudge: "if" and "do" are also control flow constructs, as are "try" and "catch".
15:51	TimMc	fliebel: There's also the question of how many Clojure needs, vs. how many the compiler special-cases.
15:51	mudge	then what is the difference between a form and a construct?
15:51	TimMc	Some of the special-cased forms could be implemented (less efficiently?) as macros.
15:51	TimMc	mudge: I'm not familiar with the term "construct".
15:54	nickik	a form is basiclly everything right?
15:54	TimMc	yeah
15:54	Scriptor`	that's how I think of it
15:56	TimMc	A form is what the reader reads when you ask it to read one form. :-P
16:00	leeda	I have [sandbar "0.3.0"] in my :dependencies and I ran "lein deps", but when I try to do (:use sandbar.core) I get the following error: https://gist.github.com/b6d2e03a93eac874d048
16:01	leeda	It looks like hiccup and sandbar are incompatible? I'm not even using hiccup in this namespace though.
16:06	raek	leeda: looks like this is a bug in sandbar that has been fixed in the snapshot version... https://github.com/brentonashworth/sandbar/commit/4c48185af93b5a86f5c5c38b8e2bcc8a8a676bc0
16:06	leeda	raek: Oh, cool. Thanks!
16:06	raek	that's why you shouldn't use 'use' without :only, folk!
16:06	leeda	yup
16:07	TimMc	"only use :use with :only"
16:17	kephale	hrm, so if one needs an entire namespace the proper thing to do is :require with :as?
16:17	clojurebot	namespaces are (more or less, Chouser) java packages. they look like foo.bar; and corresponde to a directory foo/ containg a file bar.clj in your classpath. the namespace declaration in bar.clj would like like (ns foo.bar). Do not try to use single segment namespaces. a single segment namespace is a namespace without a period in it
16:25	tomoj	TimMc: seems like the question of how many special forms we need is complicated by java interop
16:26	tomoj	I mean, does it count if you can implement the rest of the special forms in terms of the basis you pick, or do you have to finish c-in-c?
16:34	Tcepsa	#join #emacs
16:34	Tcepsa	Whoops, sorry >_<
16:36	TimMc	kephale: Yeah, that seems to work pretty well. clojure.string (or whatever) :as s, etc.
16:37	TimMc	tomoj: Yeah, I'm excluding Java interop, I don't know how it is even implemented.
16:37	mudge	anybody know where the documentation is for ->>
16:37	mudge	?
16:38	nickik	,(doc <<-)
16:38	clojurebot	Cool story bro.
16:38	nickik	,(doc ->>)
16:38	clojurebot	"([x form] [x form & more]); Threads the expr through the forms. Inserts x as the last item in the first form, making a list of it if it is not a list already. If there are more forms, inserts the first form as the last item in second form, etc."
16:38	mudge	nickik: I don't understand that documentation, is there further explanation on the web?
16:39	mudge	i don't know what " Threads the expr through the forms." means
16:40	nickik	its just puts the first argument you give it to the last position of the secend argument
16:41	mudge	nickik: can you give an example?
16:41	nickik	,(macroexpand-1 '(->> "test" (count))
16:41	clojurebot	EOF while reading
16:41	nickik	,(macroexpand-1 '(->> "test" (count)))
16:41	clojurebot	(count "test")
16:42	Scriptor	mudge: check out clojuredocs.org
16:42	nickik	,(macroexpand-1 '(->> "test" (count) (+ 5) (- 4))))
16:42	clojurebot	(clojure.core/->> (clojure.core/->> "test" (count)) (+ 5) (- 4))
16:42	Tcepsa	mudge: And then takes the result of _that_ and uses it as the last argument of the following function call, if there's another one, etc.
16:42	leeda	how would you write a function to turn all the keys of a map into keywords (if they are strings)?
16:44	mudge	i get it
16:44	nickik	(apply map (map (fn [[k v]] [(keyword k) v]) mymap))
16:44	nickik	something like that
16:45	mudge	okay, what's the difference between -> and ->> ?
16:45	nickik	mudge, -> puts it to the second position, ->> to the last
16:45	Tcepsa	nickik: should the first "map" in that be "hash-map"?
16:45	nickik	yes
16:46	leeda	nickik: oh, thanks
16:46	mudge	nickik: thanks
16:46	Scriptor	,(doc hash-map)
16:46	clojurebot	"([] [& keyvals]); keyval => key val Returns a new hash map with supplied mappings."
16:47	Scriptor	hmm, why not call it map-hash?
16:48	nickik	(apply hash-map (mapcat (fn [[k v]] [(keyword k) v]) {"a" 1 "b" 2 "c" 3}))
16:49	nickik	,(apply hash-map (mapcat (fn [[k v]] [(keyword k) v]) {"a" 1 "b" 2 "c" 3}))
16:49	clojurebot	{:a 1, :c 3, :b 2}
16:49	nickik	now it works
16:50	tomoj	TimMc: well.. I meant more the java implementation than interop. e.g. "apply" isn't implemented using clojure's special forms, so is that cheating?
16:54	hiredman	,(let [m {:a 1}] (zipmap (keys m) (map inc (vals m))))
16:54	clojurebot	{:a 2}
16:55	hiredman	,(let [m {:a 1}] (zipmap (map name (keys m)) (vals m)))
16:55	clojurebot	{"a" 1}
17:00	mudge	is it just me or is facebook really slow?
17:05	nickik	its build on php what did you think would happen?
17:14	Scriptor	tbh, php that's compiled to C++
18:33	void_	meh, what should I do about cyclic load dependency?
18:33	Raynes	Redesign.
18:33	void_	that's the only way?
18:33	Raynes	Yep.
18:41	raek	void_: in my expedience so far with Clojure, dependencies between namespaces with purely functional code tends to be cycle-free (or "layered") naturally
18:41	raek	this is quite different from java, where classes often have to have cyclic dependencies
18:42	void_	I just didn't expect that having cyclic dependencies would break everything
18:42	void_	Just used to C.
18:42	void_	Anyway, I fixed it by redesigning.
18:53	mudge	(GET "/browse/" request (let [[ns var] (str/split (get-in request [:params ""]) #"/")]
18:53	mudge	(html
18:53	mudge	(layout
18:53	mudge	(namespace-browser (namespace-names))
18:53	mudge	(var-browser ns (var-names ns))
18:53	mudge	(var-detail ns var)))))
18:53	mudge	what is "request" in this: (GET "/browse/" request (let [[ns var] (str/split (get-in request [:params ""]) #"/")]
18:53	mudge	(html
18:53	mudge	(layout
18:53	mudge	(namespace-browser (namespace-names))
18:53	mudge	(var-browser ns (var-names ns))
18:53	mudge	(var-detail ns var)))))
18:53	mudge	?
18:53	mudge	where does request come from?
18:54	raek	mudge: gist.github.com next time :)
18:54	raek	mudge: from whatever calls your handler with a request
18:55	raek	í.e. probably jetty
18:55	mudge	raek, okay, i will
18:59	mudge	what is this: #"/"
18:59	mudge	what is the # syntax?
19:00	raek	mudge: regex literal
19:01	mudge	reak, so #"/" is a regular expression that just means / then?
19:01	raek	yes
19:09	dnolen	IBM's Watson used Prolog ... need to implement DCG's for core.logic
19:10	nickik	dnolen, what how?
19:10	nickik	i mean for what?
19:12	dnolen	parsing
19:13	nickik	I think it was kind of cheating that watson got the "questions" as text.
19:14	kephale	nickik: it depends what you think they were advertising…
19:14	kephale	the turing test has no speech recognition requirement
19:16	nickik	kephale, yeah but I thought the idea of watson was that it could play just like a human, with the same conditions.
19:17	kephale	well, yeah they didn't achieve that requirement for sure. even though they made that cute point that it had a buzzer presser
19:17	kephale	but, if you want to hassle them, a human has to carry its own energy store : P
19:17	kephale	and presumably fit on the stage
19:18	nickik	hehe
19:18	kephale	oh the imagery that comes to mind… : P
19:18	nickik	i gues that will take some more time.
19:19	nickik	give moors law a couple moore (hehe) years.
19:19	kephale	lol
19:21	nickik	I want to be able to ask my phone questions.
19:21	nickik	looking stuff up on wikipedia is to much work.
19:26	TimMc	nickik: I think they also imposed a slight delay on Watson.
19:28	gigamonkey	When did they submit the text? When Trebek started reading the question or when he finished?
19:29	TimMc	dunno
19:42	mudge	I am looking for a request function takes a URL string and returns a map of response data.
19:43	mudge	anybody know what namespace the request function is in?
19:45	brehaut	mudge: clj-http
19:45	brehaut	probably clj-http.core ?
20:09	quotemstr	What's the least ugly way of incorporating some imperative code in the middle of a -> sequence?
20:09	brehaut	write a named function?
20:10	quotemstr	Context is here: http://paste.lisp.org/display/122594 It's not Clojure, but it is Clojure's thrush operator.
20:10	brehaut	-> isnt thrush; its a form rewriting macro
20:11	brehaut	thrush is a function composition macro
20:11	brehaut	quotemstr: http://blog.fogus.me/2010/09/28/thrush-in-clojure-redux/
20:11	chouser	thrush is a function composition function
20:11	brehaut	whoops yes
20:11	chouser	:-)
20:12	quotemstr	Sure. I'm just wondering whether there's a more idiomatic way of embedding those assertions.
20:12	brehaut	thanks chouser :)
20:12	quotemstr	Ah.
20:12	brehaut	monads are a _less_ idiomatic way of production compositonal imperative code ;)
20:14	brehaut	s/production/??/
20:14	sexpbot	<brehaut> monads are a _less_ idiomatic way of ?? compositonal imperative code ;)
20:14	brehaut	producing perhaps is what i meant
20:15	brehaut	quotemstr: -?> might do what you want. its in contrib somewhere
20:16	brehaut	-?>
20:16	brehaut	,-?>
20:16	clojurebot	java.lang.Exception: Unable to resolve symbol: -?> in this context
20:16	brehaut	clojure.contrib.core
20:16	brehaut	http://clojuredocs.org/clojure_contrib/clojure.contrib.core/-_q%3E
20:20	[mattb]	anyone here used clojure on android yet?
20:29	quotemstr	I guess what I _really_ want is do-notation.
20:29	quotemstr	[mattb]: AIUI, Dalvik doesn't run Clojure code well.
20:33	[mattb]	ah
20:33	[mattb]	I'm seeing lots of slow startup and memory hogging on google but it seems like that should be remediable
20:37	quotemstr	I wonder why nobody's added more elements of do-notation to ->.
20:38	Scriptor	quotemstr: which elements is it missing?
20:38	quotemstr	Scriptor: Conditionals would be nice. I suppose it's not really a monad, so trying to shoehorn that idea into it might lead to unexpected surprise.
20:42	Scriptor	,(-> 3 (= 3) (if "hi" "hello"))
20:42	clojurebot	"hi"
20:43	Scriptor	,(-> 3 (= 4) (if "hi" "hello"))
20:43	clojurebot	"hello"
20:43	Scriptor	quotemstr: what's wrong with using conditionals like above?
20:43	quotemstr	Scriptor: (if (something-p ...) ...)
20:44	quotemstr	Scriptor: Also, your example destroys the "3" value, unless I'm missing something.
20:44	Scriptor	that it does, unless you def it somewhere I guess
20:44	Scriptor	it's like using a stack language but with only one thing ever in the stack
20:45	quotemstr	Right: so you have to manage a stack yourself.
20:46	quotemstr	Scriptor: And it's not trivial to shoehorn normal functions into that model. Without using an embedded lambda like my jezt-passthrough above, it's not clear how one could print "hi 3" instead of "hi".
20:47	quotemstr	Of course, it's also possible that my sense for functional programming has been forever ruined by exposure to LOOP. :-)
20:49	quotemstr	Another idea is to create something like a half ->: instead of threading the last value into the next form's first argument position, it would just provide an anaphoric variable instead.
20:49	Scriptor	quotemstr: hmm, would it also be necessary to be able to print something like "hi 3 true" (given that the conditional returned true)
20:50	Scriptor	what's an anaphoric variable?
20:51	quotemstr	Scriptor: A variable introduced to refer to some value previously computed, but not explicitly bound.
20:51	Scriptor	ah, got it, like %1 and the like?
20:51	quotemstr	The canonical example is AIF: (aif (* a b) (1+ it) 0)
20:51	quotemstr	Yeah, I think you can look at them that way.
20:53	TimMc	,(if-let [a (+ 3 4)] (* a a) "no")
20:53	clojurebot	49
20:53	TimMc	eh, that was already bound I guess
20:53	tomoj	quotemstr: I think rich didn't like that idea
20:53	Scriptor	one idea I'm playing with is something like that, but use it to refer to a stack and make a pseudo-stack-lang
20:53	quotemstr	tomoj: Which one?
20:53	tomoj	anaphora in a more powerful ->
20:54	quotemstr	I mean, I can get tolerable syntax with -> using ugly macros, but Haskell's solution looks cleaner to me.
20:54	quotemstr	tomoj: Ah, too bad.
20:54	quotemstr	tomoj: What about explicit bindings?
20:54	TimMc	I think people have written some explicit threading macros that give you something like (--> 5 (* 3 % %) (+ % 1) (println %))
20:54	quotemstr	(-> 4 (+ 2) (<- first (+ 2)) (= 2) ... (+ first))
20:55	quotemstr	TimMc: Any pointers?
20:55	TimMc	Sorry, no.
20:55	tomoj	quotemstr: what would explicit bindings look like?
20:55	tomoj	TimMc's example is what I was thinking of, rich didn't like the semantics of % there I think
20:55	Scriptor	something like the <- example from above, tomoj
20:56	tomoj	oh, I didn't notice that second arrow
20:56	TimMc	tomoj: The problem being that % should really refer to the first thing only?
20:56	tomoj	at least that it should only refer to one thing, iirc
20:56	TimMc	ah, OK
20:57	TimMc	I'd like to see his reasoning on that.
20:57	TimMc	He's usually right, in my opinion, but sometimes it isn't clear until I've heard him talk about it fo 15 minutes in a presentation. :-P
20:59	Scriptor	or at a bar!
20:59	quotemstr	Heh.
20:59	tomoj	can't seem to find the discussion
21:00	tomoj	hardly anyone calls it "thrush" and searching for "thread[ing]" isn't exactly useful
21:01	Scriptor	was it on irc? Any place to look at them publicly?
21:01	Scriptor	(look at the irc logs)
21:02	tomoj	http://groups.google.com/group/clojure/msg/1eb5cf8fa3248049
21:03	tomoj	http://clojure-log.n01se.net/
21:04	tomoj	that above the logs is rich on an arrow extension
21:04	tomoj	the rest of the discussion is pretty entertaining I think, crazy dude
21:04	tomoj	I notice he says "And anything like let-> that allowed you to name the arg has the same problem. There is no good name, as the semantics of the parameter often change with each invocation." but don't really understand what he means
21:05	tomoj	oh
21:05	tomoj	that's not your <- suggestion, he just means letting you name the % in TimMc's -->
21:06	Scriptor	looks like the proposer is saying that the wildcard variable changes depending on the last form evaluated?
21:06	quotemstr	Indeed. My suggestion would make names consistent at least.
21:07	tomoj	I do enjoy overusing the arrows and get a bit frustrated when there's one small piece that doesn't work..
21:08	TimMc	I think one take-away from that thread is that -> and ->> are already convenience macros, and that generalizing them is going one step too far.
21:08	TimMc	i.e., if you need complexity, name it
21:09	Scriptor	right, otherwise you're getting kind of close to making an actual stack language
21:09	TimMc	I guess the places where I have really wanted it are in Java interop, though -- I need to call a whole damn chain of FactoryFactoryIterators or whatever to get the instance I want.
21:10	Scriptor	doesn't .. chain its arguments?
21:10	Scriptor	(sorry, clojure newb here)
21:17	TimMc	meh, you get the idea
21:17	TimMc	"stitchpoints", they're called
21:19	tomoj	I have never seen those
21:19	Scriptor	apparently Rich hates them too
21:19	quotemstr	TimMc: Also ungoogleable.
21:20	quotemstr	Nearly. Found the logs.
21:22	TimMc	I wonder where I saw it then.
21:22	TimMc	I wonder if Rich is worried about the likely horrible misuses of a generalized stitching macro.
21:23	Scriptor	he might not want them to be too commonly used, it's more of an imperative construct
21:23	TimMc	People would compose large chunks of code using it, and Clojure would maybe even become known for being unreadable to newcomers because of them.
21:23	TimMc	(worst-case scenario)
21:24	TimMc	I would certainly rather have people name things.
21:24	Scriptor	I liked LearnYouAHaskell describing functional programming as defining more than describing steps, so stitching does the reverse of that
21:26	TimMc	Scriptor: Regarding imperative... one of Clojure's big selling points is easy Java interop, so easy imperative coding is actuallypretty important.
21:27	TimMc	OK, I'm out for the night.
21:40	brweber2	is that a form of map that is not lazy? I know it is trivial to force the evaluation, but I'm wondering what the most idiomatic way is?
21:41	brweber2	there, not that ... oops
21:48	tomoj	why?
21:48	clojurebot	why not?
21:48	tomoj	are you mapping with a side-effecting function?
21:58	nathanmarz	brweber2: (doall (map ...))
21:58	brweber2	tomoj exactly, I am mapping a side effecting function
21:59	tomoj	don't do that :(
21:59	brweber2	nathanmarz: thanks. That's what I have, I was just wondering if there was an existing function I didn't know about that does that
21:59	brehaut	brweber2: doseq is more common for side-effecty sequence stuff
21:59	tomoj	I prefer doseq, but if you're doall'ing it's not so bad since chunks won't bite you
22:00	brweber2	tomoj: brehaut: thanks!
22:01	brehaut	brweber2: it supports comprehension notation (like for) and has an implicit do
22:01	tomoj	&(->> (range) (map print) (take 3))
22:01	sexpbot	⟹ (012345678910111213141516171819202122232425262728293031nil nil nil)
22:01	tomoj	that's what scares me
22:03	brweber2	tomoj: You've got the whole chunk of 32 there... it realized them all even though you only need three. Which function introduced the chunking in your example?
22:04	brehaut	brweber2: range
22:04	brehaut	range and vectors are (currently) the only source (i think) of chunked seqs
22:04	tomoj	which means this weirdness can be hidden if you pass unchunked seqs, then pass a chunked seq in and bam
22:05	brweber2	yeah, i wish default chunk size was 1... and you had to explicitly change it
22:05	brweber2	You'd still have this problem, but you'd have to introduce it yourself
22:06	brehaut	its very rarely a problem in real code
22:06	brehaut	side effects are the major complication
22:06	brehaut	(there is a niche of complex computations that are also bad with them, but they are rare)
22:07	tomoj	ackermann function or something?
22:08	brehaut	that sounds right
22:08	brweber2	brehaut: I simply prefer the easier to reason about solution as the default. Then again, I don't have to write a performant programming language, so I can espouse whatever naive opinions I may hold :)
22:08	brehaut	brweber2: the merits of both defaults were debated in great detail at the time it was implemted
22:09	brweber2	brehaut: I somewhat recall... I just haven't touched clojure in a while. Getting back into the swing ...
22:09	brehaut	chouser wrote an explicit dechunker function somewhere i recall
22:09	brehaut	get back into seesaw, its nicer than straight swing
22:10	brweber2	brehaut: Oh no, not that SWING! haha I wouldn't touch that with a ten foot pole
22:15	dnolen	you easily can wrap ranges and vectors in a lazy-seq to defeat chunking.
22:16	brehaut	oh of course. clever
22:16	brehaut	i had tried list, but i don tthink that works
22:17	brweber2	dnolen: are you sure?
22:17	dnolen	brweber2: not sure, positive.
22:18	brweber2	&(->> (lazy-seq (range)) (map print) (take 3))
22:18	sexpbot	⟹ (012345678910111213141516171819202122232425262728293031nil nil nil)
22:18	brweber2	dnolen: is that what you meant? Learn me! Learn me! ;)
22:18	dnolen	brweber2: that's not what I'm calking about
22:18	brweber2	dnolen: Figured not since it doesn't seem to work. Which form do you mean?
22:20	dnolen	(defn lazier [x] (if x (lazy-seq (cons (first x) (lazier (next x))))))
22:23	brweber2	dnolen: Gotcha. That does the trick. Is that identical to the dechunker written by chouser mentioned before?
22:24	dnolen	brweber2: no, that solution involves deftype.