#clojure – 2012-07-28

2012-07-28

00:02	teurastaja	if i dont know java, should i learn it before learning clojure? i know scheme
00:04	emezeske	teurastaja: Knowing some java basics will probably make your life easier
00:06	arohner_	let's say you have a datastructure, that's a (ref {}). In general, you do you write defns that take the ref, or the deref'd map?
00:06	teurastaja	what features does someone who uses clojure and doesnt know java misses
00:06	teurastaja	?
00:07	arohner	teurastaja: don't bother "learning" java. Just write what you want to write, and learn java lazily
00:08	emezeske	teurastaja: Well, for one thing, the error messages you will get from the clojure compiler are just java stack traces
00:08	teurastaja	can one write a metacircular interpreter in clojure alone?
00:08	arohner	yes
00:09	teurastaja	does it have continuations?
00:09	teurastaja	can it do systems programming?
00:10	arohner	no
00:10	teurastaja	no for which?
00:10	arohner	both, on the JVM
00:11	arohner	you can use JNA or JNI to load and call C libraries, but it wouldn't be useful for embedded systems, or interrupt handling
00:11	teurastaja	so what are clojures strengths
00:11	teurastaja	?
00:11	arohner	It's a practical lisp
00:12	arohner	a lot of people use it for web stuff, and map reduce kinds of things
00:13	arohner	and it's good anywhere you'd use java, python or ruby
00:14	teurastaja	clojure vs common lisp vs scheme...?
00:16	arohner	clojure has much better multi-threading support. The UI bindings are good enough. It can be trivially embedded in any existing java program
00:16	arohner	probably bigger community at this point
00:19	arohner	you get to use JVM web servers and JVM DB drivers, so you can 'steal' from existing java libs when needed
00:20	teurastaja	java is not really an argument for me but its goode to know
00:21	teurastaja	what networking protocols does it support?
00:22	Raynes	*
00:23	emezeske	teurastaja: You want an exhaustive list?
00:24	arohner	java is good in the sense that there's usually an available library for interacting with the outside world. If you're just going to be doing project euler, then yeah, you probably don't need it
00:27	teurastaja	just want to be sold clojure so i know if its good for me
00:28	arohner	what are you looking to do with it?
00:34	teurastaja	things i cant do easily with scheme
00:34	teurastaja	i dont know exactly
00:58	Raynes	If you can't easily do something in Scheme, it's usually related to there not being a library for it.
02:15	jestinepaul	Why is my membership to clojure-dev google group still pending? I have already sent my CA last week.
10:17	xumingmingv	I know that there is a function named assoc-in to put something into a nested structure
10:17	xumingmingv	why there is no corresponding function to remove something from the nested structure?
10:18	xumingmingv	user=> (swap! x assoc-in [:handlers :lst 0] "hello")
10:18	xumingmingv	{:handlers {:lst ["hello"]}}
10:18	xumingmingv	how do i remove the "hello" I just assoc-ined?
10:20	uvtc	xumingmingv: dissoc
10:20	xumingmingv	uvtc: I'd expect there is a dissoc-in
10:20	xumingmingv	but apparently there is no dissoc-in in clojure.core
10:22	uvtc	The clojuredocs for dissoc mention a dissoc-in in the legacy monolithic contrib... Is that now somewhere in the current contrib libs?
10:24	xumingmingv	just found the update-in, seems that's what I want
10:24	xumingmingv	maybe just because update-in is more useful than dissoc-in
11:11	bordatoue	could anyone tell me how to change a value of a variable within a loop , for example maininting a running total of sequence
11:13	augustl	bordatoue: pass it as an argument
11:13	augustl	(recur (inc i))
11:14	bordatoue	is there any other option without using recur
11:15	augustl	bordatoue: what's wrong with recur?
11:15	uvtc	bordatoue: what in particular are you trying to do?
11:16	bordatoue	uvtc: augustl i want to konw if this possible using doseq
11:16	augustl	bordatoue: not that I'm aware, just recur it I guess :)
11:17	uvtc	bordatoue: If what's possible using doseq?
11:17	bordatoue	so what is purpose of doseq,
11:17	clojurebot	doseq is like for, but for side effects instead of values
11:18	bordatoue	okay, in py- for i in range(10): print i, i+10, i+=i , how do i do this in clojure using doseq
11:18	bordatoue	not recur
11:18	rlb	bordatoue: say you want a program that prints the integers, increasing, one per line -- doseq might be useful.
11:18	augustl	bordatoue: why do you have to use doseq?
11:18	augustl	bordatoue: you can use a ref or an atom or whatever, but that seems like a very bad idea
11:18	bordatoue	because doseq is like for ,
11:19	augustl	but you can't do what you want to do with doseq
11:19	xumingmingv	we cannt remove an item from the middle of a vector or list, right?
11:19	rlb	(doseq [x (range)] (prn x))
11:19	uvtc	&(doseq [i (range 10)] (let [j (+ i 10)] (println i j)))
11:19	lazybot	⇒ 0 10 1 11 2 12 3 13 4 14 5 15 6 16 7 17 8 18 9 19 nil
11:20	uvtc	bordatoue: ^^
11:20	bordatoue	uvtc: , would you be able to add the new value to i in your example using doseq
11:21	bordatoue	i+=i+10
11:21	bordatoue	i+=10
11:21	uvtc	Oh, right, you want to keep a running total.
11:21	bordatoue	yes,
11:21	bordatoue	i want to chang the binding within a loop
11:22	bordatoue	wihtout using recur
11:22	augustl	bordatoue: why is that?
11:22	bordatoue	augustl: swap function
11:22	rlb	bordatoue: are you saying "can I write a C style for loop in clojure"? If so, then no, not easily.
11:22	rlb	(and not efficiently)
11:22	bordatoue	if x>y then x=y
11:23	rlb	bordatoue: but there are other ways to accomplish whatever you're trying to do.
11:23	bordatoue	rlb: can you find a sloution using doseq
11:23	bordatoue	and let
11:23	craigbro	hola
11:24	bordatoue	rlb would you be able to find a max of a given range of number using doseq not using recur or max fn
11:24	thorwil	bordatoue: (min x y) ?
11:24	rlb	bordatoue: loop/recur is clojure's closest analog to for.
11:24	rlb	(C-style for)
11:24	rlb	doseq is not
11:24	bordatoue	rlb: in that case , when should we use doseq
11:24	augustl	bordatoue: doseq is for doing side effects on sequences
11:24	augustl	such as calling methods on java objects
11:25	rlb	bordatoue: whenever you want to traverse a sequence and produce side-effects.
11:25	craigbro	and not return anything?
11:25	rlb	(as the docs say)
11:25	rlb	Right
11:25	craigbro	like printing a list of strings
11:25	uvtc	bordatoue: you might be looking for `reduce`.
11:25	bordatoue	rlb: okay , then why can't you find max of a given range of numbers using doseq
11:25	craigbro	but I don't care about the return value
11:26	bordatoue	uvtc: i don't want to use other fn
11:26	ToxicFrog	bordatoue: because it's the wrong tool for the job, and you're asking the wrong question.
11:26	rlb	bordatoue: the same reason you can't do it with prn?
11:26	ToxicFrog	It's like asking "why can't I read a file using printf"
11:26	craigbro	boardatoue you could actually
11:26	ToxicFrog	craigbro: don't give him ideas, it's going to be ugly
11:26	bordatoue	if doseq helps to iterate a sequence then all that is left to swap a values
11:27	augustl	bordatoue: you don't seem to understand what a side effect is
11:27	craigbro	bordatoue: you would use a atom
11:27	bordatoue	craigbro: can you provide an example , i
11:27	augustl	bordatoue: since you're promtly ignoring that part :)
11:27	ToxicFrog	bordatoue: doseq is for when you have a lazy sequence and you need to force it to be evaluated because generating the sequence involves side effects that you care about.
11:27	bordatoue	augustl: i do know side effect, fn that are not pure
11:27	ToxicFrog	It is not a general purpose iteration construction.
11:27	rlb	bordatoue: and technically, yes, you could do it in clojure with an atom or simlar, but that would be "the wrong way" (and inefficient).
11:28	rlb	i.e doseq + let + atoms
11:28	augustl	bordatoue: here's an example of doseq https://www.refheap.com/paste/3855
11:28	craigbro	bordatue: yah, let to bind an atom to a variable, and then inside your doseq you reference the atom and swap! the new max in
11:28	craigbro	bordatoue: but that's shitty
11:29	rlb	It's a complete misuse of clojure -- like using a file for the same purpose in C.
11:29	craigbro	bordatoue: specifically, you end up with alot of overhead for accessing the atom value and swapping the new value in
11:29	rlb	though it you're just interested in it for academic purposes, then yes, it'll work.
11:30	bordatoue	so if you are given a sequence and what to iterate it , then doseq isn't the right tool
11:30	augustl	scroll up ;)
11:30	craigbro	bordatue depends on the type of iteration you want, and what you want out of the iteration
11:31	craigbro	bordatoue: think of it like the old saying that eskimos have a hundred words for snow
11:31	bordatoue	augustl: i saw it , but is it wrong to do soemething like doseq [x (range 10)]
11:31	craigbro	bordatoue: lisps, have a half dozen ways to process a list.
11:31	craigbro	bordatoue: and the differences appeart sublte and unimportant at first
11:32	augustl	bordatoue: that's ok, if you're calling functions that have side effects and pass in x
11:32	bordatoue	so every time we are given a seq then it is loop and recur we need to use
11:33	craigbro	bordatoue: not really. you can use map, filter, reduce, select, doseq, or a loop/recur, just for starters
11:33	rlb	bordatoue: no, you'll probably more often want map/reduce/filter/etc.
11:33	rlb	bordatoue: or for.
11:33	bordatoue	i thought loop and recur should be rarely used as there are HOF functions
11:33	craigbro	bordatoue: hmm, never heard of that opinion before
11:34	augustl	HOF = higher order functions?
11:34	rlb	bordatoue: you can often use the other functions, but you'll still be using loop/recur reasonably often -- of course, depends on what you're doing.
11:34	augustl	I've never used them I think :)
11:35	craigbro	bordatoue: it might be helpful to think of these as tools for transofrming a list, or reducing a list
11:36	rlb	...and I would be surprised if loop/recur is more common at first, for anyone coming from more strictly imperative languages.
11:36	rlb	s/would/wouldn't/
11:37	rlb	bordatoue: often you can recast your problem to use the other functions (i.e. max. min, etc.)
11:37	bordatoue	(let [x 10] ... (let [x (+ x 10)] ...)) ,can anyone explain what happens with the stack allocation
11:37	bordatoue	basciall i have got one outer let with binding to x and inner let with binding to x
11:38	craigbro	in my 15k+ line app, loop is used 5 times
11:38	craigbro	and most of those are in code I have for walking tree-zipper data structures
11:38	craigbro	a naturaly "recursive" task
11:38	bordatoue	i just want to know if x ref to same object
11:38	rlb	bordatoue: no
11:38	rlb	bordatoue: the inner binding shadows the outer one.
11:38	craigbro	inner will shadow outer in the code that is lexically (typographically) inside the inner let
11:39	craigbro	they will not point to the same object
11:40	craigbro	also, letting something is not the same as saying "push this value onto the stack and let me refer to it as x"
11:40	ToxicFrog	Yeah, I have yet to use loop or recur at all
11:40	rlb	...and the system is welcome to gc the outer bits iff they're no longer reachable, but I have no idea what clojure actualy does, implementation-wise wrt to that.
11:40	craigbro	in some lisp implementations it is close to that tho
11:40	bordatoue	craigbro: what happens during letting
11:43	rlb	bordatoue: conceptually, the inner x and the outer x are two different variables/names, bound to two different values.
11:43	bordatoue	thanks
11:43	rlb	code can only see the "nearest" binding
11:45	bordatoue	so if you are given a seq what is best way to iterate them lazily without using take,loop,first,rest,map,reduce,
11:45	ToxicFrog	...why would you want to avoid using those?
11:46	craigbro	sorry, network bounce
11:46	bordatoue	i just want to know if it is possible to write a fn that would return a max of value in a given seq without using any high order funtions or loop and recur , also atom . just using let and doseq
11:47	antares_	bordatoue: for but I see no reasons to avoid take, map, filter, reduce and so on
11:47	bordatoue	ofcourse no max or min
11:47	craigbro	bordatoue: sure, you can use doseq, and an atom
11:47	bordatoue	antares_: this is just for understanding what can be done with the language ,
11:47	craigbro	bordatoue: an atom is a way to have mutable state in clojure
11:48	craigbro	bordatoue: avoiding HOFs in a lisp is not advised 8)
11:48	rlb	bordatoue: are you allowed to use fn?
11:48	bordatoue	so craigbro, what happens during atom operation does it use CAS
11:48	craigbro	CAS?
11:48	clojurebot	paredit screencast is http://p.hagelb.org/paredit-screencast.html
11:48	bordatoue	rlb: that is good way, acutally you could pass it as an argument
11:49	bordatoue	CAS compare and swap
11:49	craigbro	rlb: I end up doing that with macros alot, when I want a macro that binds a bunch of helper variables
11:49	rlb	bordatoue: and loop/recur is (more or less) just syntactic sugar for recursion (i.e. recursive fn calls).
11:49	craigbro	bordatoue: the atom itself doesn't give a fuck, but yah, you could compare and swap
11:49	craigbro	an atom is just a box
11:49	bordatoue	but jvm does not do a Tail call optims
11:49	craigbro	loop/recur handles that for you
11:50	bordatoue	is atom just a box like the var
11:50	ToxicFrog	bordatoue: no, but the clojure compiler does (by translating it into forms that the JVM can process in constant stack space)
11:50	rlb	but no, doeseq has no way to preserve state across sequence elements
11:50	craigbro	like a var, but you can change it, and the ways you change it handle synchronization and all that
11:51	rlb	bordatoue: doseq can not do it, by itself
11:51	craigbro	http://clojure.org/Atoms
11:51	rlb	(since you said "no atoms" above)
11:52	bordatoue	okay thanks everybody, very informative
11:52	craigbro	socratic method!
11:54	uvtc	I wonder why clojurebot pointed out that paredit screencast above...
11:54	uvtc	CAS?
11:54	clojurebot	paredit screencast is http://p.hagelb.org/paredit-screencast.html
11:54	uvtc	Hm.
11:54	craigbro	SCREE
11:54	craigbro	SCREE?
11:54	clojurebot	paredit screencast is http://p.hagelb.org/paredit-screencast.html
11:54	craigbro	PARE?
11:54	clojurebot	paredit tutorial is http://p.hagelb.org/paredit-outline
11:54	craigbro	OUTLINE?
11:54	craigbro	weird
11:54	uvtc	Didn't know about those pages. Nice.
11:55	duck1123	that's why clojurebot told you, he knew you hadn't seen the paredit screencase
11:55	uvtc	The uncanny clojurebot.
11:58	casion	is there a page that has a list of common algorithms and/or tasks in clojure?
11:58	casion	i know of rossetta code, anything elsse?
12:01	uvtc	A cookbook, perhaps?
12:01	uvtc	casion: Maybe some at http://en.wikibooks.org/wiki/Clojure_Programming#Cookbook.
12:02	_zach	Is there a core fn that can convert a map of the form {index val} into a seq/vec where index corresponds to the index of the val in the new seq?
12:03	casion	uvtc: most othe stuff there is beyond me atm, but thank you :)
12:03	_zach	such that {0 :x 1 :y 3 :z} => (:x :y nil :z)
12:05	rlb	casion: for educational purposes, clojures own code for various operations can also be helpful.
12:05	rlb	s/clojures/clojure's/
12:06	rlb	casion: and if you haven't seen them, there are links to the source in the documentation.
12:06	tmciver	,(vals {0 :x 1 :y 3 :z}) ; _zach
12:06	clojurebot	(:x :y :z)
12:06	tmciver	nope, but close
12:06	casion	thanks rlb
12:06	_zach	tmciver: indeed, thanks
12:07	uvtc	_zach: Hm.. You might first start with `(vals m)` ...
12:07	rlb	i.e. http://clojuredocs.org/clojure_core/clojure.core/reverse#source
12:07	uvtc	Oh, wait. `map-indexd`.
12:08	_zach	uvtc: I think I have something figured out. I'll post my solution in a second.
12:08	_zach	there's likely a nicer way.
12:08	uvtc	&(map-indexed (fn [idx entry] [idx (val entry)]) {:a "aa" :b "bb" :c "cc"})
12:08	lazybot	⇒ ([0 "aa"] [1 "cc"] [2 "bb"])
12:09	uvtc	_zach: er, though maybe I didn't read your question carefully enough.
12:10	_zach	uvtc: :) I have a map where index => val
12:10	_zach	so {3 :d 2 :c 0 :a 1 :b} should become (:a :b :c :d)
12:11	uvtc	_zach: Ok, so you want `(vals m)`, but you want them sorted by their keys in `m`.
12:11	_zach	uvtc: Exactly.
12:12	Bronsa	user=> (vals (into (sorted-map) {3 :d 2 :c 0 :a}))
12:12	Bronsa	(:a :c :d)
12:12	tmciver	_zach: but you also want indexes missing from the map to be represented as nil in the ouput, right?
12:12	_zach	tmciver: Yes.
12:17	uvtc	&(for [e (sort (fn [a b] (compare (a 0) (b 0))) (seq {3 :d 2 :c 0 :a 1 :b}))] (e 1))
12:17	lazybot	⇒ (:a :b :c :d)
12:17	uvtc	_zach: ^^
12:17	uvtc	So, take a seq of the map to turn it into a list of entries,
12:17	Guest82661	where do I find a core.logic binary(jar?) published? Sonatype or something?
12:17	uvtc	then sort those entries by their keys,
12:18	mich2	here do I find a core.logic binary(jar?) published? Sonatype or something?
12:18	uvtc	_zach: and finally use `for` to just take the 2nd item of each entry.
12:18	_zach	uvtc: Thank you for this solution. I think Bronsa had another one as well, which is (vals (into (sorted-map) {3 :d 2 :c 0 :a 1 :b}))
12:19	Bronsa	,(#(vals (into (into (sorted-map) (map vector (range (inc (reduce max (keys %)))) (repeat nil))) %)) {0 0 3 3 1 1})
12:19	clojurebot	(0 1 nil 3)
12:19	Bronsa	this way you get also missing keys
12:19	_zach	Bronsa: Awesome!
12:19	Bronsa	I'm sure it can be done better but this is the first way that came to my mind
12:19	_zach	Bronsa: Thank you for your help. uvtc as well.
12:20	uvtc	_zach: Ah, missed that. ... Oooh, Bronsa's is nicer. :)
12:28	tmciver	_zach: here's another for good measure: ##(take 5 (map {0 :x 1 :y 3 :z} (range)))
12:28	lazybot	⇒ (:x :y nil :z nil)
12:29	alex_baranosky	I'm trying to connect to clojure jack in, via M-x clojure-jack-in -- I have a project.clj file that I can use fine from lein repl. However when I try to use clojure-jack-in from Emacs it just says: "Starting swank server…" (and nothing else happens)
12:29	_zach	tmciver: I was just writing that same thing :). Thanks!
12:30	alex_baranosky	any ideas what might be the issue?
12:31	duck1123	alex_baranosky: if you check the hidden buffers, there's probably one that has the output of the jack-in call
12:31	tmciver	alex_baranosky: I get that problem after I kill a previously running swank.
12:32	duck1123	M-x slime-selector c (I think)
12:38	alex_baranosky	hmmm… my swank buffer had this message in it: "Process swank exited abnormally with code 127
12:38	alex_baranosky	zsh:1: command not found: lein"
12:39	lnostdal	hi, (class (Long. (int 261))) ==> java.lang.Long but (class (Long. (Integer. 261))) ===> No matching ctor found for class java.lang.Long what's going on here?
12:40	alex_baranosky	I just reproduced it -- every time I redo M-x clojure-jack-in it is giving me an extra entry in the swank buffer
12:43	alex_baranosky	I think I've found the issue: Emacs isn't configured to get my PATH from my .zshrc
12:43	alex_baranosky	http://stackoverflow.com/questions/9435019/how-do-i-source-my-zshrc-within-emacs
12:44	duck1123	I hate emacs on osx due to the path issues
12:45	uvtc	duck1123: I'm not crazy about the issue there with having that extra Command/Clover key...
12:45	duck1123	I don't think I ever got my path quite right. I ended up just setting up a vm
12:46	duck1123	I use a MBP, but I run my emacs over SSH forwarding from my linux server. I can't tell you how many times I've gone to copy, and closed the entire window
13:01	xumingmingv	I want to develop a producer-consumer queue, if use java, I will use ConcurrentLinkedQueue, how to do it in clojure?
13:08	xumingmingv	http://stackoverflow.com/questions/11703024/producer-consumer-queue-in-clojure
13:22	antares_	xumingmingv: typically some queue implementation from j.u.c. is sufficient. Consumer can just loop and take/remove/poll items in a separate thread.
13:23	xumingmingv	is it possible to implement it in pure clojure way?
13:24	xumingmingv	...because clojure is claimed to be very good at concurrency programming, dont know if i understand it correctly? antares_
13:25	antares_	xumingmingv: it is possible to implement a lot of things in just Clojure, but why would you reinvent j.u.c. queue implementations?
13:25	antares_	there are not that many ways in which you can improve them
13:26	xumingmingv	antares_: my intension is not to beat j.u.c
13:26	antares_	if you insist on having a Clojure version, use an atom that stores a collection. Appending items to it is as straightforward as (swap! an-atom conj item)
13:27	antares_	consuming correctly is a bit trickier but also will use swap! and sequence/collection operations
13:29	xumingmingv	yeah, this is what in mind now(use atom, swap!), but if multiple threads producing/consuming the messages concurrently
13:29	xumingmingv	then I need to use ref and dosync
13:29	antares_	xumingmingv: why?
13:29	antares_	atom is atomic reference
13:29	antares_	it is pretty hard to be safer than that
13:30	xumingmingv	oh, maybe I didnt really understand atom, let me learn it again \|o\|
13:31	antares_	for just one identity (like a queue), using a ref over an atom makes no sense. It will work the same way but carry more overhead.
13:32	xumingmingv	so it is safe to have multiple threads adding/removing from the collection in a atom?
13:32	xumingmingv	concurrently
13:34	devn	"Changes to atoms are always free of race conditions."
13:34	xumingmingv	but the performance is bad, right? because the swap! use compare-and-set, so technically the producer and consumer cannt adding/removing items from the atom at the same time
13:40	duck1123	xumingmingv: this is probably not what you're looking for, but have you looked at lamina?
13:41	xumingmingv	thanks duck1123 devn antares_
13:41	devn	xumingmingv: the comment on your SO post is worth looking into -- clojure.lang.PersistentQueue
13:44	devn	xumingmingv: maybe you do want a ref... hm...
13:44	xumingmingv	devn, how to solve this concrete problem is not really my biggest concern
13:44	xumingmingv	duck1123, devn: I think what I'm really confused is that: clojure is claimed to be good at concurrency programming, but for this producer-consumer case we need to looking java for help
13:45	duck1123	I think it's less that you need to look to clojure, but rather that java already has it covered
13:45	duck1123	look to java
13:46	antares_	xumingmingv: Clojure makes concurrency easier where Java itself does not. Clojure was designed to be a symbiotic/hosted language. Why reinvent concurrent queues if there is already several implementations in the JDK?
13:48	devn	xumingmingv: clojure.lang.PersistentQueue is a clojure thing.
13:52	xumingmingv	thanks all, maybe I just too focused on solve problems using pure clojure
13:53	devn	xumingmingv: clojure.lang.PersistentQueue is "pure" clojure.
13:53	devn	it also used to be implemented using ConcurrentLinkedQueue
13:53	xumingmingv	devn: haha I will take at look at it
13:55	devn	now i feel bad -- i am now thinking he probably shouldn't use persistentqueue :\
13:58	craigbro	haha
14:36	ToxicFrog	devn: it kind of feels like you could implement reader/writer architectures in clojure without needing a shared queue at all, to me
14:36	ToxicFrog	And possibly should
15:27	michaelr525	good evening!
15:47	cldwalker	hi all, anyone know of a parser for maven-metadata.xml? if not I was just going to do it with clojure.xml/parse
15:50	cldwalker	_ato: this is for showing clojar dependencies, thoughts?
15:52	Frozenlock	Amazing to see how the channel is slower on weekends
15:52	Frozenlock	in/on weekends?
16:09	cldwalker	nevermind, found org.apache.maven.artifact.repository.metadata.io.xpp3.MetadataXpp3Reader
16:47	KyleBrodie	hola clojurians
16:47	duck1123	hello
16:48	KyleBrodie	hows it going?
16:48	duck1123	pretty good, you?
16:48	KyleBrodie	alright. are you an experienced clojurian?
17:18	duck1123	I've been using clojure for a couple years. There are certainly better than me. Did you have a question?
17:30	dsantiago	Does clojurescript support clojure's (.fieldname myrecord) access style on defrecords?
17:45	hiredman	dsantiago: (.-
17:46	dsantiago	Ah.
19:40	presto	Is there a way of introducing a local binding without having to use it in a new scope (IOW: introducing a binding in the current scope)? For instance: (let a 1) so I can use 'a' in the next statements instead of inside the 'let' form.
19:41	presto	Also: would this be a good idea? Why?
19:44	antares_	,(let [a 1 b a] b)
19:44	clojurebot	1
19:44	antares_	presto: if I understand your question correctly, that is very common
19:45	antares_	but you can only use locals inside a scope created with let, if-let, with-open and so on
19:45	presto	antares_, not quite. I mean something like (let a 1) a ; return 1
19:45	presto	As you would do in Javascript, for instance. var a = 1; a;
19:46	brainproxy	presto: how about def
19:46	brainproxy	(def a 1)
19:46	presto	brainproxy, def introduces the binding in the whole thread, as far as I know, not only in the current scope.
19:46	brainproxy	oh sorry, didn't read your question carefully enough
19:47	antares_	presto: no necessarily the whole thread but namespace, yes
19:47	presto	I mean, using (let [?] ?) is no big deal, but I guess that it would be easier to teach (and sometimes visually), if it would have some parallel with other dynamic languages, where doing a simple "a = b; b" would suffice.
19:47	presto	antares_, oh ok.
19:47	antares_	presto: that's what let does
19:47	antares_	and let-like forms
19:48	brainproxy	(let [a b] (...) (...) )
19:48	presto	antares_, indeed, but you have to use the bindings inside the let form. That's my point.
19:48	antares_	presto: yes and that is by design
19:49	antares_	you can have the entire function body to be a let statement, there is nothing wrong with that
19:50	presto	antares_, sure, I do get that.
19:50	presto	My point is that it is still one level deeper that it would be if let would introduce the bindings in the current scope, instead of creating a new one.
19:51	presto	I'm not saying that it's wrong, by the way. :D
19:51	gfredericks	presto: that kind of makes it more imperative than expression-based
19:51	brainproxy	presto: can you gist an example where let and def don't give you quite what you want?
19:51	presto	Just that it would be simpler to teach someone as an introductory language if that was not the case.
19:51	presto	gfredericks, yes, I do agree with you there.
19:52	gfredericks	presto: have you had trouble teaching programming-beginners non-imperative languages?
19:52	antares_	presto: in that case you would have a lot more unexpected side effects (well, shadowing)
19:52	presto	brainproxy, they both do. My point is not about functionality. Just about how it looks for a beginner.
19:53	antares_	which is not unheard of in JavaScript, for example, where scoping is one of the most common sources of issues
19:55	presto	gfredericks, well, yes, and imperative ones as well. But I'm not a teacher anyway, I probably suck at explaining things. :D
19:56	brainproxy	presto: okay, i think i get it, you're suggesting that it may seem complicated to a beginner to have to introduce/nest a let statement in order to create a binding
19:56	antares_	it would be a serious disservice to beginners
19:56	antares_	it would be convenient for the first 3 days
19:56	antares_	then they would start hitting the same issues as in JavaScript
19:56	casion`	so with a condp, you have an expression, then if the expression matches one of the values... the subsequent predicate is returned immediately, correct?
19:56	brainproxy	yeah, have to agree, coming from a few years of javascript
19:57	casion`	no concept of break; it just returns the predicate?
19:57	casion`	and goes to the next expresssion?
19:58	antares_	explicit scoping is not "right" but it does discipline and protect you from many issues that have nothing to do with your problem's complexity
19:58	antares_	casion`: yes, "first match wins"
19:59	presto	antares_, Javascript do have issues, but I think you're referring to some specific one that is related to binding values, right?
19:59	casion`	what's the difference with (cond _ _) then?
19:59	presto	antares_, like forgetting to use "var"?
19:59	antares_	yes, that kind of issues, implicit scoping
19:59	brainproxy	yes, particularly inside of a function definition
19:59	brainproxy	if you're reusing a var name
20:00	brainproxy	but your intent is actually to shadow
20:00	presto	I see, well I'm doing only javascript nowadays (more than one year), I don't remember having binding issues but I'm using a javascript compiler, which do catch errors. So I guess I'm not the common case...
20:01	casion`	condp seems like a simple switch with implicit breaks, I get that (I assume I do)... what would the C equivalent of cond be then?
20:01	gfredericks	presto: I find clojure's let much easier to reason about than anything imperative
20:02	presto	gfredericks, yes, I also don't see any problem reasoning with let forms.
20:02	presto	I guess what I'm saying is...
20:02	presto	If there was a kind of let form that would introduce a binding in the current scope, I would probably use it sometimes.
20:03	gfredericks	and most clojure users would get angry at anyone who used it
20:04	presto	Yes, it's not Clojure-y. :D Not even Lispy I think.
20:05	presto	Anyway? I was just wondering if I was missing something. Thank you guys.
20:05	gfredericks	casion`: I don't think condp is like anything in C; nor cond; case is probably pretty similar to what you're describing
20:05	casion`	gfredericks: gah, why can't this shit all be like C :P
20:06	gfredericks	cuz then we wouldn't have much reason to use it
20:06	hyPiRion	casion`: condp would be like, hmm
20:06	casion`	someone should make C-lojure
20:06	casion`	gfredericks: yeah, well I'm learning this sspecifically because it's nothing like what I'm used to
20:06	casion`	still frustrating at times
20:06	hyPiRion	(cond expr1 stat1 expr2 stat2 expr3 stat3 ...) -> if (expr1) {stat1} else if (expr2) {stat2} else if ....
20:07	gfredericks	casion`: I've been using clojure for years and have never once used condp and didn't know what it did
20:07	hyPiRion	Oh wait, condp.
20:07	casion`	hyPiRion: I'm getting a bit lost in the differenc between cond and condp
20:08	hyPiRion	&(doc condp)
20:08	lazybot	⇒ "Macro ([pred expr & clauses]); Takes a binary predicate, an expression, and a set of clauses. Each clause can take the form of either: test-expr result-expr test-expr :>> result-fn Note :>> is an ordinary keyword. For each clause, (pred test-expr expr) is evalu... https://www.refheap.com/paste/3861
20:08	gfredericks	casion`: but I use cond all the time
20:08	antares_	casion`: cond matches on equality. condp lets you decide what to use to match.
20:09	antares_	casion`: also, everything in Clojure is an expression while in C it is usually the opposite. I think you want cond, not condp.
20:09	hyPiRion	antares_: cond isn't matching on equality, I think you're talking about case.
20:09	gfredericks	that :>> thing is a little ugly; I hadn't ever seen that before
20:09	antares_	err
20:10	casion`	ok ok
20:10	casion`	I think maybe I get it?
20:10	casion`	condp is an expression, followed by value predicate pairs, if the value matches the expression the predicate is returned
20:10	antares_	hyPiRion: more or less, I was talking about cond but did not explain it correctly
20:11	antares_	case is used even more often than cond
20:11	casion`	cond is just expresssion predicate pairs
20:11	hyPiRion	casion`: It's probably best with examples, I'll give you the cdoc examples in a second.
20:11	casion`	hyPiRion: ok thank you
20:12	antares_	casion`: so yes, you probably want case. cond is a nice way to avoid some if … elseif … elseif kind of code.
20:13	casion`	antares_: it's not so much of what I want, I'm just learning atm
20:13	hyPiRion	casion`: https://www.refheap.com/paste/3862
20:13	casion`	going through code and referencing
20:14	casion`	what is :>>
20:14	casion`	I haven't come across that yet
20:15	antares_	just a keyword
20:15	antares_	it could be :joe
20:15	antares_	or :rightright
20:15	antares_	this example seems to be from http://clojuredocs.org/clojure_core/clojure.core/condp
20:16	casion`	ah
20:16	hyPiRion	casion`: Think of it like this: :>> means that you're using a function on the value given instead of a value to return.
20:16	casion`	the second example there was confusing me for a second
20:18	hyPiRion	so for instance, (condp even? n true (inc n) false (dec n)) would be the same as (condp even? n true :>> inc false :>> dec)
20:19	casion`	hmm
20:19	antares_	I am afraid that's even more confusing :)
20:19	casion`	I understand, but I also don't
20:19	casion`	:>> is just a normal keyword?
20:19	hyPiRion	Yeah
20:19	casion`	I don't get how :keyword form works there?
20:20	casion`	or am I confused even more than I think
20:20	antares_	casion`: don't worry about it, I think case and cond are what you really need to understand to work with Clojure, condp is rarely used
20:20	hyPiRion	I would recommend you to do the following: Ignore the :>> usage and use the "standard" way of using condp
20:21	casion`	will I be encoutnering that syntax elsewhere?
20:21	hyPiRion	Not as far as I know.
20:21	casion`	the :>> inc instead of say (inc n)
20:22	hyPiRion	I don't believe so, casion`.
20:22	gfredericks	casion`: the :>> only distinguishes the ternary case from the binary case; you should, though, get used to seeing functions referenced without being called
20:22	gfredericks	that is the nature of a functional language
20:23	casion`	gfredericks: I believe I understand that
20:23	casion`	but I don't get why :>> inc does anything?
20:23	gfredericks	:>> is specific to condp
20:24	gfredericks	the fact that it's used that way is very peculiar in clojure; I've never seen it anywhere else
20:25	gfredericks	anywhere else in clojure I mean
20:25	gfredericks	(not "in any other language")
20:27	casion`	I'm stuck on it saying "Note :>> is an ordinary keyword."
20:27	casion`	I understand what it is doing
20:27	gfredericks	it probably has the note there because that usage is so weird that nobody would expect it
20:28	gfredericks	casion`: do you know what a keyword is?
20:28	casion`	gfredericks: I thought I did, but I'm doubting that now
20:28	gfredericks	casion`: what do you think a keyword is?
20:29	casion`	a unique identifier for a value
20:29	hyPiRion	gfredericks: It's kind of interesting though, I don't understand how they figure out that it's the ternary case, and not the binary one.
20:30	gfredericks	hyPiRion: yeah since :>> is a function presumably it might be the binary case. I assume you just can't ever use :>> as a function; #(:>> %) if you really want to
20:30	gfredericks	casion`: what other languages are you familiar with?
20:30	Chousuke	casion`: keywords are not identifiers in clojure. they are simply things that evaluate to themselves
20:31	casion`	gfredericks: C/asm (in a few contexts)
20:31	Chousuke	you can use keywords as macro syntax for that reason
20:31	gfredericks	Chousuke: no, you could use anything in macro syntax
20:31	casion`	gfredericks: I've done most entirely embedded development
20:31	hyPiRion	So I don't understand which one is used here, for instance: https://www.refheap.com/paste/3863
20:31	Chousuke	gfredericks: well, you could, but keywords are a good choice
20:31	casion`	clojure is my first functional language, or 'high level language'
20:31	Chousuke	gfredericks: since then you won't be hijacking anything
20:32	gfredericks	Chousuke: symbols are nicer
20:32	gfredericks	Chousuke: you hijack any usage of the keyword as a function, which we discussed a couple minutes ago
20:33	gfredericks	casion`: okay, well keywords are similar to strings, but they are used in contexts where the only thing you would care to do with them is compare them to other keywords (for equality); a lot of their uses is similar to enums in static languages
20:33	Chousuke	enums? hm :/
20:34	Chousuke	they are good for anything that needs a constant. map keys usually.
20:35	casion`	hmmm
20:35	casion`	trying to process this
20:35	gfredericks	they are very good as map keys
20:35	casion`	keywords and guaranteed unique?
20:36	casion`	are*
20:36	gfredericks	not sure what that means
20:36	casion`	a map
20:36	gfredericks	:foo and :foo are the same
20:36	casion`	udh, sorry
20:36	casion`	yes
20:36	casion`	my brain is overloading apparently.
20:36	augustl	strings require string compare, symbols are memory address compares, so to speak
20:36	augustl	since :foo and :foo points to the same memory
20:37	gfredericks	yes keywords compare in O(1) while strings compare in O(n)
20:37	Chousuke	yeah you can't have two keywords that are both :foo and not the same object
20:37	gfredericks	,(identical? :foo (keyword "foo"))
20:37	clojurebot	true
20:37	Chousuke	not without some hideous hackery anyway
20:37	hyPiRion	well, you do have ::
20:37	hyPiRion	,::foo
20:37	clojurebot	:sandbox/foo
20:37	Chousuke	that's different
20:38	casion`	so it's like a const pointer then?
20:38	Chousuke	:foo/bar is still ::foo/bar
20:38	Chousuke	:foo/bar :P
20:38	Chousuke	damn typos
20:38	hyPiRion	,::foo/bar
20:38	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: Invalid token: ::foo/bar>
20:38	casion`	an identifier that always evaluates to the same address space?
20:38	hyPiRion	hah.
20:38	Chousuke	casion`: I'm not sure if it's an identifier. it's just an object
20:38	casion`	ok
20:38	gfredericks	casion`: that's true, but it's an implementation detail; really keywords are like strings
20:39	gfredericks	they are used in ways that you would not use strings in a low-level language because it wouldn't be efficient
20:39	Chousuke	casion`: and the semantics of keywords are such that iff a keyword has the same name as another, they are the same object
20:39	casion`	gfredericks: ok, that makes sense
20:40	casion`	you can compare keywords at runtime?
20:40	gfredericks	yep
20:40	hyPiRion	yes.
20:40	gfredericks	,(= :foo :bar)
20:40	clojurebot	false
20:40	gfredericks	,(= :baz :baz)
20:40	clojurebot	true
20:40	Chousuke	you can store keywords in data structures. they're just data.
20:41	gfredericks	,(= [:foo] (list :foo))
20:41	clojurebot	true
20:41	casion`	,(= :right (keyword (str "ri" "ght")))
20:41	clojurebot	true
20:41	casion`	mind bown
20:42	Chousuke	,(identical? :right (keyword "right"))
20:42	clojurebot	true
20:42	Chousuke	that's the important thing
20:42	gfredericks	casion`: those things are all true of strings as well; just not the identical? part
20:42	Chousuke	they're the same object.
20:42	gfredericks	everything that keywords are used for in clojure strings could be used as well, just a little slower
20:42	Chousuke	they use java interned strings internally :P
20:42	casion`	that is amazing to me haha
20:44	augustl	are keywords GC-ed? In Ruby, the equivalent (symbols) aren't.
20:44	augustl	so if you keywordize strings from user input that's a nice way to run out of memory
20:44	casion`	so, back to condp, I assume the :>> keyword is just used by the macro?
20:45	augustl	symbolize*
20:45	gfredericks	casion`: yes it's a special case in the macro
20:45	casion`	is there a way to see how condp expands?
20:45	gfredericks	,(source condp)
20:45	clojurebot	Source not found
20:45	gfredericks	casion`: yeah you can use macroexpand-1
20:45	gfredericks	&(source condp)
20:45	lazybot	java.lang.RuntimeException: Unable to resolve symbol: source in this context
20:54	hyPiRion	Meh, condp is ambigous.
20:57	casion`	I can't find the source for it
20:58	gfredericks	&(clojure.repl/source condp)
20:58	lazybot	⇒ Source not found nil
20:58	gfredericks	baaaah
20:59	hyPiRion	&(macroexpand-1 '(condp = foo baz bar spam egg))
20:59	lazybot	⇒ (clojure.core/let [pred__15215 = expr__15216 foo] (if (pred__15215 baz expr__15216) bar (if (pred__15215 spam expr__15216) egg (throw (java.lang.IllegalArgumentException. (clojure.core/str "No matching clause: " expr__15216))))))
20:59	hyPiRion	&(macroexpand-1 '(condp = foo baz :>> bar spam :>> egg))
20:59	lazybot	⇒ (clojure.core/let [pred__15225 = expr__15226 foo] (clojure.core/if-let [p__4925__auto__ (pred__15225 baz expr__15226)] (bar p__4925__auto__) (clojure.core/if-let [p__4925__auto__ (pred__15225 spam expr__15226)] (egg p__4925__auto__) (throw (java.lang.IllegalArgu... https://www.refheap.com/paste/3865
21:00	hyPiRion	That's basically how it works.
21:00	gfredericks	http://clojuredocs.org/clojure_core/clojure.core/condp#source
21:02	hyPiRion	hm, so it's just :>> that's affected.
21:03	gfredericks	of course
21:03	casion`	hum
21:03	hyPiRion	I was thrown off by the "Note :>> is an ordinary keyword.
21:03	casion`	I get it now
21:03	casion`	awesome
21:03	casion`	you guys are awesome
21:04	gfredericks	hyPiRion: hah; yeah the whole thing is a mess
21:04	gfredericks	(inc you-guys)
21:04	lazybot	⇒ 1
21:05	hyPiRion	I find defn- and dec' messy as well. I mean, the heck.
21:05	hyPiRion	&(doc dec')
21:05	lazybot	⇒ "([x]); Returns a number one less than num. Supports arbitrary precision. See also: dec"
21:05	ToxicFrog	,(doc dec)
21:05	clojurebot	"([x]); Returns a number one less than num. Does not auto-promote longs, will throw on overflow. See also: dec'"
21:05	ToxicFrog	Aah.
21:05	gfredericks	hyPiRion: eh; that's just performance stuff
21:05	gfredericks	dec' at least; not defn-
21:06	hyPiRion	gfredericks: it's the single quote in the name I'm a bit frightened at.
21:06	gfredericks	oh you don't like that being syntactically legal?
21:06	hyPiRion	Well, yeah.
21:07	mattmoss	It's just a name.
21:07	mattmoss	Makes me think of calculus, where f was a function and "f-prime" or f' was the first derivative.
21:07	ToxicFrog	hyPiRion: you don't like being able to write foo-prime as a name?
21:07	_ato	cldwalker:
21:08	gfredericks	I use it all the time
21:08	ToxicFrog	mattmoss: pretty sure that is exactly how it is being used here
21:08	mattmoss	Gotcha.
21:08	ToxicFrog	' is a reasonable ascii approximation of the unicode prime symbol.
21:08	hyPiRion	Well.
21:08	gfredericks	ToxicFrog: wat; you're saying dec' is the first derivative of dec?
21:08	craigbro	in H.S. only tho
21:08	ToxicFrog	gfredericks: no; foo' has more applications that just derivatives
21:08	hyPiRion	&[(dec '1.0) (dec' 1.0)]
21:08	lazybot	⇒ [0.0 0.0]
21:09	mattmoss	I've refrained from actually using myself, since I didn't see it mentioned in clojure book or other docs as being valid syntax... but maybe I didn't look hard enough.
21:09	ToxicFrog	generally A' is just "sometime derived from or closely related to A"
21:09	ToxicFrog	In calculus, by convention, this is a derivative.
21:09	mattmoss	What ToxicFrog said.
21:09	gfredericks	ToxicFrog: yes I read too much into your "that is exactly how it is being used here"
21:09	_ato	cldwalker: yes just a using a plain XML parser is what I'd do. It's simple enough calling a dedicated maven parser would be overkill. I'm sure there's a class in Aether (which Clojars depends on) which does it, but it'd probably be more work trouble to figure out how to use it than just doing it yourself.
21:09	ToxicFrog	gfredericks: yeah, sorry, that was ambiguous - I meant "it's being used as a prime symbol", not "it's being used as a derivative"
21:10	ToxicFrog	Hmm
21:11	ToxicFrog	Yeah, actually, according to the manual, dec' is not legal
21:11	gfredericks	the manual?
21:11	ToxicFrog	Well, the reader reference on the website, http://clojure.org/reader
21:11	ToxicFrog	"Symbols begin with a non-numeric character and can contain alphanumeric characters and *, +, !, -, _, and ? (other characters will be allowed eventually, but not all macro characters have been determined)."
21:11	mattmoss	ToxicFrog: Yeah that.
21:12	gfredericks	it's old then
21:12	mattmoss	Using ' as part of identifier seems to work, but I've refrained from doing so because I hadn't found any reference that supported it.
21:12	ToxicFrog	,(defn f' [x] x) (f' 1)
21:12	clojurebot	#<Exception java.lang.Exception: SANBOX DENIED>
21:12	ToxicFrog	&(defn f' [x] x) (f' 1)
21:12	lazybot	java.lang.SecurityException: You tripped the alarm! def is bad!
21:12	gfredericks	mattmoss: rich hickey supports it
21:12	ToxicFrog	eat me lazybot
21:12	hyPiRion	&(let [f' (fn [x] x)] (f' 1))
21:12	lazybot	⇒ 1
21:12	ToxicFrog	Thank you.
21:13	mattmoss	gfredericks: That's good enough for me... just finding it in any doc/reference is lacking.
21:13	ToxicFrog	gfredericks: yeah, but if it's not documented...
21:13	gfredericks	ToxicFrog: it was documented verbally at the first clojure conj :)
21:13	gfredericks	he said "Now you can put primes on your symbols"
21:13	mattmoss	Ah.
21:13	ToxicFrog	gfredericks: word-of-mouth doesn't count as documentation :P
21:13	hyPiRion	&(let [!' (fn [x] x)] (!' 1))
21:13	lazybot	⇒ 1
21:14	hyPiRion	&(let ['! (fn [x] x)] ('! 1))
21:14	lazybot	java.lang.Exception: Unsupported binding form: (quote !)
21:14	hyPiRion	So the quote is a special case: Cannot occur at start of name.
21:14	gfredericks	ToxicFrog: my point was it's not an accident
21:14	hyPiRion	/s/name/symbol
21:14	ToxicFrog	gfredericks: yeah, I didn't expect it was, I'm just saying the docs need to be updated
21:14	gfredericks	hyPiRion: yes it has a different meaning at the start
21:15	gfredericks	clojure.org doesn't get a lot of compliments
21:15	hyPiRion	&(let [?'! (fn [x] x)] (?'! 1))
21:15	lazybot	⇒ 1
21:15	hyPiRion	Well, that's creative at least.
21:16	gfredericks	,'%foo
21:16	clojurebot	%foo
21:16	gfredericks	% is a fun one; can only be initial
21:16	hyPiRion	what.
21:16	hyPiRion	,'%%
21:16	clojurebot	%
21:17	gfredericks	,'[%%]
21:17	clojurebot	[% %]
21:17	gfredericks	%% just makes two of them
21:17	hyPiRion	Woah.
21:17	hyPiRion	,'[%''%]
21:17	clojurebot	[%'' %]
21:18	gfredericks	the worst thing in the current reader that I know of is clojure.core//
21:18	hyPiRion	I don't like that one either, heh.
21:18	gfredericks	,(read-string "clojure.core//")
21:18	clojurebot	clojure.core//
21:18	gfredericks	,(read-string "something.else//")
21:18	clojurebot	#<RuntimeException java.lang.RuntimeException: Invalid token: something.else//>
21:19	ToxicFrog	what
21:19	hyPiRion	heh. It's the special case of the specials.
21:19	mattmoss	Obfucscated clojure?
21:19	hyPiRion	But actually...
21:19	hyPiRion	&(let [/ *] (/ 2 3))
21:19	lazybot	⇒ 6
21:20	hyPiRion	And you can defn it too.
21:53	howard_	Hello Clojurians!
21:54	howard_	I have a question regarding using = to compare lists. Why does (def a 1) (= '(a) '(1)) return false?
21:55	howard_	however, (= [1] [a]) is true
21:55	howard_	:-(
21:56	gert	'(a) is a list with the symbol a
21:56	gert	that's not equal to a list with the number 1
21:56	howard_	ok thanks
21:56	howard_	so does that mean a is not a symbol in [a]?
21:57	gert	the difference is in using the quote ' character
21:57	mattmoss	,(= (list a) '(1))
21:57	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve symbol: a in this context, compiling:(NO_SOURCE_PATH:0)>
21:57	mattmoss	silly me
21:57	gert	(def a 1) (= (list a) (list 1))
21:57	howard_	aha!
21:57	gert	that will work
21:57	howard_	thank you Matt and Gert
21:58	gert	no worries
21:58	mattmoss	,(let [a 1] '(a))
21:58	clojurebot	(a)
21:58	howard_	Now I will be more careful when using quote :D
21:58	mattmoss	,(let [a 1] [a])
21:58	clojurebot	[1]
21:59	gert	,(let [a 1] (list a))
21:59	clojurebot	(1)
21:59	gert	voila :)
22:00	gert	howard_: you could also say (def a 1) (= `(~a) `(1))
22:01	gert	if you really don't like to use "list"
22:01	howard_	i love everything Clojure
22:01	howard_	hehe..
22:06	gfredericks	,(let [a 1] `(~a))
22:06	clojurebot	(1)
22:08	howard_	let me try and see if this works..
22:08	howard_	,(slurp "/etc/hostname")
22:08	clojurebot	#<SecurityException java.lang.SecurityException: denied>
22:08	howard_	nope :D
22:09	howard_	,(print "ha")
22:09	clojurebot	ha
22:10	howard_	,(loop [] (recur))
22:10	howard_	,(print "hehe")
22:10	clojurebot	hehe
22:10	hyPiRion	timeout.
22:10	clojurebot	Execution Timed Out
22:10	howard_	clever
22:13	hyPiRion	,set!
22:13	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve symbol: set! in this context, compiling:(NO_SOURCE_PATH:0)>
22:15	gfredericks	,(doc set!)
22:15	clojurebot	Excuse me?
22:18	hyPiRion	Gurr. I want an immutable map to contain itself. Is there some trick to that?
22:19	howard_	,(do (declare b) (def b (atom {:b b})))
22:19	clojurebot	#<Exception java.lang.Exception: SANBOX DENIED>
22:20	howard_	eh, it worked for me
22:21	hyPiRion	declare and def are scary.
22:21	howard_	:D
22:21	gert	it won't happen howard_. a service evaluating clojure forms, on the public internet, is really not going to be that insecure
22:22	howard_	also it is powered by Clojure
22:22	hyPiRion	However, it's not working properly. b doesn't contain itself.
22:22	howard_	i just realized that..
22:22	gert	at the time you're defining your atom, b is nil. So your atom holds {:b nil}
22:23	gfredericks	whatever you guys do will end up being essentially not an immutable map anymore
22:23	hyPiRion	gert: b is unbound, actually.
22:23	gert	ah yes, true
22:23	howard_	yeah... it's always unbound
22:23	howard_	let me try other ways
22:23	hyPiRion	gfredericks: That's sad, because there's nothing "illegal" pointing to itself. :(
22:24	hyPiRion	You're not mutable if you do that.
22:24	gfredericks	it's not a finite value though
22:24	hyPiRion	No, but neither is an infinite list.
22:24	hyPiRion	Both are immutable.
22:27	howard_	,(do (declare a) (def a {:self (atom a) :data 7}) (:data (ref (:self a)))
22:27	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
22:27	howard_	,(do (declare a) (def a {:self (atom a) :data 7}) (:data (ref (:self a))))
22:27	clojurebot	#<Exception java.lang.Exception: SANBOX DENIED>
22:28	howard_	the bot doesn't take atoms?
22:28	hyPiRion	You can't def anything.
22:29	howard_	well i just found a way...
22:29	howard_	probably isn't exactly what you want
22:29	hyPiRion	,(condp #(get %2 %1) {:>> {:>> :>>}} :>> :>> :>>)
22:29	clojurebot	:>>
22:30	howard_	,(let [m (:self (fn [] m))] ((:self m)))
22:30	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve symbol: m in this context, compiling:(NO_SOURCE_PATH:0)>
22:30	howard_	eh..
22:30	hyPiRion	heh, you need to declare it, which is rather hard in a sandbox
22:30	howard_	put m into def
22:30	howard_	and it worked for me
22:30	howard_	you have a self included map by using function
22:32	howard_	(def m {:self (fn[] m) :data 7})
22:32	howard_	(:data ((:self m)))
22:32	howard_	that works
22:33	howard_	test color code
22:34	hyPiRion	Creative. I'll try and look for some core-hacky way of making it contain itself.
22:34	howard_	:D
22:34	howard_	good luck
22:35	hyPiRion	As of right now, I'm only able to get something like ##(let [a (transient {})] (assoc! a :a a) (persistent! a)) , which is almost there.
22:35	lazybot	⇒ {:a #<TransientArrayMap clojure.lang.PersistentArrayMap$TransientArrayMap@15947ca>}
22:35	gfredericks	hyPiRion: what do you need this for?
22:35	hyPiRion	gfredericks: Intellectual stimulation.
22:35	howard_	slow clap
22:36	hyPiRion	It's only an interesting problem, nothing more than that. :)
22:40	gfredericks	,(let [m' (promise), m {:self m'}] (deliver m' m) m)
22:40	clojurebot	{:self #<core$promise$reify__3678@340d5852: {:self #<core$promise$reify__3678@340d5852: {:self #<core$promise$reify__3678@340d5852: {:self #<core$promise$reify__3678@340d5852: {:self #<core$promise$reify__3678@340d5852: #>}>}>}>}>}
22:41	muhoo	wat?
22:41	clojurebot	For Jswat: start clojure with -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8888
22:42	gfredericks	I think beyond that you'd have to look into hacking the private fields on the map classes
22:45	hyPiRion	gfredericks: heh.
22:47	hyPiRion	Oh well, I'll look at it tomorrow.
22:48	howard_	what is the difference between a Cons and a list?
22:49	howard_	i'm wondering why i cannot use peek in Cons
22:49	howard_	.(peek '(1 2))
22:49	howard_	,(peek (cons 1 '(2 3))
22:49	clojurebot	#<ExecutionException java.util.concurrent.ExecutionException: java.lang.RuntimeException: EOF while reading>
22:49	howard_	,(peek (cons 1 '(2 3)))
22:49	clojurebot	#<ClassCastException java.lang.ClassCastException: clojure.lang.Cons cannot be cast to clojure.lang.IPersistentStack>
22:49	howard_	:-(
22:49	howard_	,(first (cons 1 '(2 3)))
22:49	clojurebot	1
22:49	howard_	oh, first works..
22:49	hyPiRion	,(doc peek)
22:49	clojurebot	"([coll]); For a list or queue, same as first, for a vector, same as, but much more efficient than, last. If the collection is empty, returns nil."
22:50	hyPiRion	So it's undefined for Conses.
22:50	howard_	,(doc first)
22:50	clojurebot	"([coll]); Returns the first item in the collection. Calls seq on its argument. If coll is nil, returns nil."
22:50	alandipert	howard_: cons returns a seq (not a concrete data structure), not a list
22:50	howard_	i see..
22:51	howard_	thank you
22:51	howard_	is there a way to pop more than one item from a stack (list)?
22:51	howard_	,(doc pop)
22:51	clojurebot	"([coll]); For a list or queue, returns a new list/queue without the first item, for a vector, returns a new vector without the last item. If the collection is empty, throws an exception. Note - not the same as next/butlast."
22:52	howard_	,(pop (pop (pop '(1 2 3 4))))
22:52	clojurebot	(4)
22:52	howard_	meh... that solves the problem but i wanna pop 100 from stack
22:53	gfredericks	(apply comp (repeat 100 pop))
22:53	howard_	so it makes a copy of the stack each time an element is popped?
22:53	hyPiRion	No.
22:53	howard_	ok great!
22:54	alandipert	,(drop 3 '(1 2 3 4)) ; if you can deal in seqs
22:54	howard_	thanks guys!
22:54	clojurebot	(4)
22:54	hyPiRion	(reduce (fn [a _] (pop a)) [1 2 3 4 5 6] (repeat 3 nil))
22:55	hyPiRion	,(reduce (fn [a _] (pop a)) [1 2 3 4 5 6] (repeat 3 nil))
22:55	clojurebot	[1 2 3]
22:56	alandipert	,(nthrest '(1 2 3 4) 3)
22:56	clojurebot	(4)
22:57	alandipert	i think that lil guy stays a list
22:59	gfredericks	,(-> '(1 2 3 4) (nthrest 3) type)
22:59	clojurebot	clojure.lang.PersistentList
23:37	muhoo	what's the most current hello-world for cljs? is it cljs-template?
23:50	nsxt	noob question - if i've a string, say, foo.bar, and i want 'bar', i can do "ListTables"
23:50	nsxt	user=>
23:50	nsxt	wrong paste...
23:51	nsxt	i can do (second (clojure.string/split "foo.bar" #"\."))
23:51	nsxt	but that feels... unnatural?
23:52	nsxt	is there a more idiomatic way of getting "bar"?
23:52	howard_	i did it in that way too...
23:53	nsxt	alright, i'll run with it for now.
23:53	howard_	:)
23:53	howard_	by the way..
23:53	howard_	are you trying to get file extension name?
23:53	howard_	if so, use last rather than second
23:53	nsxt	no... it will always be string.string
23:53	howard_	ok
23:53	nsxt	but yes, i agree last is better
23:54	nsxt	(if there were multiple elements)
23:54	howard_	and if it is performance critical
23:54	howard_	use peek rather than second
23:54	nsxt	thanks, howard_
23:54	howard_	,(peek (clojure.string.split "foo.bar" #"\.")))
23:54	clojurebot	#<CompilerException java.lang.RuntimeException: java.lang.ClassNotFoundException: clojure.string.split, compiling:(NO_SOURCE_PATH:0)>
23:54	howard_	oops
23:54	howard_	,(peek (clojure.string/split "foo.bar" #"\.")))
23:54	clojurebot	"bar"
23:54	howard_	today i learned that peek is much faster than last :D
23:55	muhoo	also, noir-cljs or lein-cljsbuild?
23:55	nsxt	yeah, just checked clojuredocs and there's a benchmark, good to know