#clojure – 2015-01-01

2015-01-01

01:05	zophy	it is very good for you to have me wishing you a happy new year !!
01:39	rhg135	I dont know yall well but i love you all and heres to even better code in 2015
01:50	woort	Hey what is the command character for clojurebot?
01:51	rhg135	, i think
01:51	clojurebot	#<CompilerException java.lang.RuntimeException: Unable to resolve symbol: i in this context, compiling:(NO_SOURCE_PATH:0:0)>
01:51	jwm	happy newyear
01:51	woort	nice, thank you
01:51	woort	,(+ 1 1)
01:51	clojurebot	2
01:52	rhg135	,(-> #'map meta)
01:52	clojurebot	{:ns #<Namespace clojure.core>, :name map, :added "1.0", :file "clojure/core.clj", :static true, ...}
01:52	rhg135	Grr
01:53	rhg135	,clojure-version
01:53	clojurebot	{:interim true, :major 1, :minor 6, :incremental 0, :qualifier "master"}
01:54	rhg135	why is it a dynamic var tho?
02:45	kenrestivo	does core.async get upset when some consumers/producers of channels are go loops and others are jvm threads?
03:08	rhg135	kenrestivo: no which is great
03:09	kenrestivo	thanks. trying to troubleshoot deadlocked/stuck threads in a production-sized app is not fun.
03:09	kenrestivo	even converting everything to go loops, still something somewhere is locking up channels.
03:10	rhg135	id avoid threading till needed. Core.async wont care
03:26	rhg135	Good night #".+"
04:07	dagda1_	this comparison returns false (= [["dog"] ["cat"]] [["cat" "dog"]]) is there a way to compare that would compare irrespective of the order of the elements?
04:07	dagda1_	I mean this (= [["dog"] ["cat"]] [["cat"] ["dog"]])
04:09	dagda1_	this works (= (set [["dog"] ["cat"]]) (set [["cat"] ["dog"]]))
04:18	cfleming	Is it possible to macroexpand but to retain the line and column metadata?
04:18	cfleming	I can't get it to work.
04:19	cfleming	.(binding [print-meta true] (pr-str (read (LineNumberingPushbackReader. (StringReader. "(let [x (+ 2 3)] x)")))))
04:19	cfleming	,(binding [print-meta true] (pr-str (read (LineNumberingPushbackReader. (StringReader. "(let [x (+ 2 3)] x)")))))
04:19	clojurebot	#<CompilerException java.lang.IllegalArgumentException: Unable to resolve classname: LineNumberingPushbackReader, compiling:(NO_SOURCE_PATH:0:0)>
04:19	cfleming	Bah
04:20	cfleming	Anyway, that returns "^{:line 1, :column 1} (let [x ^{:line 1, :column 9} (+ 2 3)] x)" as expected
04:21	cfleming	Produces "(let* [x (map nil nil)] x)"
04:22	cfleming	Sorry, "(let* [x (+ 2 3)] x)", rather
04:22	cfleming	All the line and column data has been stripped off
04:24	cfleming	It seems that I can add metadata, but any metadata added to lists is removed - I guess this is because lists are always replaced with their macroexpansions?
04:27	amalloy	cfleming: the compiler ordinarily sets the metadata itself, but macroexpand isn't the compiler
04:28	cfleming	amalloy: But in this case it's not preserving metadata that I've set either
04:28	cfleming	amalloy: I can set ^:test on the arg vector or the binding symbol, but if I set it on (+ 2 3) it gets lost
04:29	cfleming	amalloy: This also happens with riddley, which surprised me
04:29	amalloy	clj-865 iirc is one that mentions this
04:29	amalloy	$google clj-865 jira
04:29	lazybot	[[#CLJ-865] Macroexpansion discards &form metadata - Clojure JIRA] http://dev.clojure.org/jira/browse/CLJ-865
04:29	amalloy	i guess not, really. but related
04:30	cfleming	I was going to say that's the most surprising thing I've seen lately, but there are so many...
04:30	cfleming	What a PITA
04:31	amalloy	oh wait, you used clojure.walk/macroexpand-all?
04:31	amalloy	man, just never use that function
04:31	amalloy	it gets the easy cases right-ish, but misses a lot of subtleties
04:32	cfleming	amalloy: This also happens with riddley
04:32	cfleming	Which is what I tried first
04:33	amalloy	riddley maps over lists, as i recall
04:33	amalloy	because it has to look for macros inside the list to expand
04:33	amalloy	and of course map doesn't preserve metadata
04:34	cfleming	amalloy: https://www.refheap.com/95637
04:34	cfleming	No, riddley isn't using map as far as I can see
04:35	cfleming	It has its own walking function
04:36	amalloy	i was thinking of https://github.com/ztellman/riddley/blob/master/src/riddley/walk.clj#L228, cfleming
04:36	amalloy	its walking function uses map
04:37	amalloy	but anyway your example is a weird one, because the list you provided doesn't even exist in the output at all, so it's kinda not that surprising that the metadata you put on it doesn't appear
04:38	cfleming	Right, but intuitively it seems like you would want the metadata for a macro form to be preserved on the expansion
04:38	cfleming	Maybe that's not intuitive, I dunno - it seems like it to me
04:49	zophy	i should be able to map println over a persistent list, correct ?
04:50	amalloy	yes, zophy, but it will all end in tears
04:51	amalloy	~map
04:51	clojurebot	map and the other sequence functions used to be lazy, but with the advent of chunked sequences, may or may not be lazy, consult your local ouija board
04:55	SagiCZ1	zophy: i think you are looking for doseq
04:55	SagiCZ1	,(doseq [e (range 5)] (println e))
04:56	clojurebot	0\n1\n2\n3\n4\n
05:04	zophy	SagiCZ1, and amalloy, thanks, i can get it to work with doseq :)
05:06	zophy	heh, map worked for this in the cider-repl...
05:09	SagiCZ1	map does work but it is lazy so you have to force the evaluation with doall.. and it collects the result thus wasting memory
06:18	zot1	happy 2015! any other lively nerds in here?
06:18	zot1	i'm playing with misaki, and have never seen the #- form before — what does it do?
06:19	zot1	or is this perhaps part of his dsl in some way i can't yet track down?
06:20	wagjo	zot1: cljx maybe?
06:21	zot1	could be — i've never touched cljx
06:22	wagjo	zot1: feature expressions, so that yhou can use same source file for both CLJ and CLJS
06:23	zot1	interesting
06:23	zot1	(inc wagjo)
06:23	lazybot	⇒ 1
06:26	wagjo	thanx
06:51	mi6x3m-alt	hey llasram, I managed to fix the issue
06:51	mi6x3m-alt	by delaying the initialization of the decorator
06:52	mi6x3m-alt	I moved it to a method called initialize() which is invoked after the instance is constructed
10:21	zophy	~seq
10:21	clojurebot	Titim gan éirí ort.
10:25	zophy	pog mo thoin
10:36	mi6x3m	hey llasram, you here by any chance?
12:15	dagda1_	if I have a set like this (def a #{["cat" "man"] ["man" "snake"] ["spider" "cat"]}) then why is (first a) ["man" "snake"]
12:16	mfikes	Try (seq a)
12:16	adulteratedjedi	or ffirst
12:17	mfikes	(The order is not defined, right, so any other element could be first in the seq)
12:19	dagda1_	mfikes why is it always ["man snake"
12:20	dagda1_	even (first (vec a)) returns ["man" "snake"]
12:20	mfikes	dagda1_: For that particular literal, the hash codes produced will be deterministic, but undefined. (Not truly random.)
12:20	dagda1_	mfikes: ah right, the hashcodes determine it, that makes snese
12:50	andyf	dagda1_: There is a set implementation in a library that preserves items in the order they were added, if that is useful to you. Also several ordered map variants that sort on insertion order, by values, or by a specified list of keys. See the cheatsheet for links to them: http://jafingerhut.github.io
12:53	justin_smith	dagda1_: maybe it's helpful to know that a hashset #{} is implemented as a tree, sorted by the hashcode
12:53	dagda1_	justin_smith: yes, that makes sense
12:53	justin_smith	,(hash ["cat" "man"])
12:54	clojurebot	12869706
12:54	justin_smith	,(hash ["man" "snake"])
12:54	clojurebot	1160122883
12:54	justin_smith	I guess there's still something I don't get, because I would have expected the "first" item to be the one with the smaller hash code
12:55	justin_smith	clearly it's not that simple
12:57	dagda1_	justin_smith: no, it can't be size, but there is a consistent algorithm
13:07	andyf	justin_smith: Even for sets with the same set of elements, and are thus equal, the seq orders may be different, because hash collision items are put into linked lists in order of addition to the set.
13:07	andyf	i.e. it is possible (fairly rare) to have (= s1 s2) but (not= (seq s1) (seq s2))
13:14	seangrove	Can anyone help point out the problems in cljs (and tooling) that come from not having reified namespaces?
13:14	seangrove	cemerick ^^
13:17	mi6x3m	andyf: sounds fairly possible to me
13:27	irctc	should I use deftype, records, or zippers to represent trees in clojure?
13:27	irctc	quad trees to be specific
13:27	mi6x3m	why not vectors or normal sequences?
13:28	irctc	mi6x3m: how would you recomend they be structured
13:29	arrdem	irctc: what problem are you trying to solve and why do you feel that a quad tree is in order
13:30	irctc	arrdem: looking for clusters of points in 2d space
13:31	irctc	arrdem: most of my points should be spread out in a path
13:32	irctc	arrdem: but occassionaly there may be clusters with a certain patter, I thought if the quad tree has a certain depth it indicates that there is more activity there
13:34	arrdem	so I don't think that bringing a deftype in will actually help you here
13:36	arrdem	the advice I usually see given here is that you want to prototype with a map or some other easy to work with structure and then once you get that nailed down switch to a class generating thing which is a little less flexible.
13:37	irctc	arrdem: what class generating thing? records?
13:39	arrdem	irctc: deftype and defrecord both emit a customized class which can cause problems when you're working at a REPL
13:40	arrdem	hiredman has been quoted repeatedly steering people away from those, not that they don't work they just have pitfalls.
13:41	irctc	yeah i was trying to avoid them, but all the examples for trees in clojure are using these two
13:41	irctc	when defining custom data structures, (like quad trees or whatever) I don't need to make it a new type
13:41	andyf	As was mentioned earlier, you can make trees with nested maps.
13:41	irctc	right?
13:43	andyf	If you want different types of "nodes" in your tree, you can have a :kind or :type key with a value that tells you what 'type' it is.
13:43	irctc	arrdem: I actually did that, adding stuff blows up the stack though, I could try switching the recursive calls to loop/recur, but it seemed like zippers would help
13:44	irctc	arrdem: this is what i had
13:44	irctc	http://pastebin.com/1GFqvxj6
13:48	andyf	irctc: There is a call to add-points with the wrong number of args in there, yes?
13:50	irctc	andyf: oh there might be
13:53	andyf	You never have x or y coordinates the same as in other points? If you do, next-quad will return nil
13:55	andyf	It seems like how balanced this quad-tree is depends heavily about the value of :len, and how spread out the points are that you are adding.
13:56	andyf	Seems you could easily end up with a long skinny tree with very little or no branching.
13:56	andyf	s/heavily about/heavily upon/
13:57	andyf	I haven't implemented a quad tree before, or looked at what variants exist, but I'd bet there are rebalancing variants that are more complex to implement, but guaranteed to avoid that problem regardless of the order in which points are added.
13:59	justin_smith	andyf: a quick search tells me for balancing you want k-D trees, which are a superset of octrees, which are a superset of quadtrees
14:01	justin_smith	but it is trickier than regular balancing via rotation, because these trees have extra invariants that a linear tree does not
14:01	andyf	that wouldn't surprise me.
14:02	justin_smith	that is, you can see a normal red-black tree as a balanced 1d tree, where a quad tree is a unbalanced 2d, octree unbalanced 3d, k-d-tree balanced n-d
14:03	justin_smith	"The algorithm checks whether there could be any points on the other side of the splitting plane that are closer to the search point than the current best. In concept, this is done by intersecting the splitting hyperplane with a hypersphere around the search point that has a radius equal to the current nearest distance."
14:03	andyf	I also wouldn't be surprised if there is a rebalancing quad-tree for 2d that avoids some of the complexity of higher dimensions.
14:04	justin_smith	could be, but k-d generalizes both up and down
14:21	irctc	andyf: that's probably true
14:21	irctc	andyf: yeah, i didn't account for edges
14:23	rritoch	Does anyone know how to fix a multiline regex so it doesn't break the java stack if there's no end to the match? https://github.com/rritoch/lein-sablecc/blob/master/src/leiningen/sablecc/compile.clj#L33
14:24	rritoch	I made this code to strip out block comments so it would ignore any Package declarations in comments, but if there's a '/' in the grammar, and no comment to close it / */ I get a java stack error.
14:38	kenrestivo	huh, i've run into a situation where async/alts! locks up hard, even if there's a timeout, the timeout never fires.
14:38	kenrestivo	(async/alts! [kill-chan ins (async/timeout timeout)])
14:39	kenrestivo	according to tools.trace, alts! gets called, but never returns.
15:10	ticking_	I wonder why clojure allows for nil in collections while it disallows it in chans. Hindsight?
15:15	godd2	ticking_ perhaps because in a channel, you can be waiting for the next thing. You wouldn't shove nil through a channel, because empty space is simply waiting for the next thing to process. however in a collection, the space between members is discrete, so the only way to represent empty space between members is with nil.
15:16	godd2	since the default is "sit there and do nothing" for a channel, it's redundant to send a message which tells it to not do anything
15:16	ticking_	godd2: good explanation, but I wonder if :custom/nothinghere elements would be cleaner
15:17	godd2	Well I mean, if you think of the real world, sure, you can always send someone an empty box.
15:17	justin_smith	ticking_: checking for truthy vs. falsey is more concise than checking for :custom/nothinghere
15:18	godd2	but it doesn't make sense to, let's say in a restaurant, send a cook an order with nothing on the ticket.
15:18	ticking_	nil to me is the value of "something nonsensical" so a collection with elements of a certain problem domain should contain the placeholder elements of said domain
15:18	justin_smith	maybe the empty message could just be :yo/sup
15:18	hellofunk	i'd enjoy any tips on making this little algorithm more elegant, which i'm sure is possible: https://gist.github.com/hellofunk/caf3de6b465d6e2ab2f6
15:18	godd2	ticking_ ah, well I'd say that nil isn't "nonsense", its just not anything else
15:19	godd2	its the answer to the question "what is a number which is even and odd?"
15:19	godd2	the question isn't nonsense, the answer is that there aren't any
15:20	ticking_	justin_smith: yeah but I would rather dispatch on my custom element than have an ambiguous (first []) (first [nil]) :/, maybe it's just a matter of taste though
15:21	borkdude	how to check for byte-array with prismatic/schema?
15:22	ticking_	godd2: you mean as in (and (even? x) (odd? x)), but the answer to that is ironically false :P
15:22	ticking_	,(and (even? 0) (odd? 0))
15:22	godd2	no, that's the answer to the question "is this number even and odd"
15:22	clojurebot	false
15:23	borkdude	got it (Class/forName "[B")
15:23	godd2	which is different from what I stated previously
15:24	ticking_	godd2: if you mean that the answer to "what is a number which is even and odd?" is nil, I'd disagree to
15:24	godd2	ticking_ oh? you have a different answer?
15:25	ticking_	godd2: ah good I understood correctly now :), yeah because nil is not a number
15:25	godd2	:P
15:26	godd2	now, in the restaurant example, if the cook came up and asked the servers if there was any work to be done, then nil would make sense, but that wouldn't be a channel anymore
15:27	ticking_	godd2: In the restaurant example I would expect the waiter to return a collection
15:27	ticking_	godd2: same goes for the ticket of work to be done
15:27	ticking_	godd2: clojure separates nil from '() for that reason right?
15:28	godd2	ticking_ right. its the difference between "give me the number which..." and "give me the list of numbers which..."
15:28	godd2	because an empty list has properties which nil does not
15:28	godd2	for example, you can put things into an empty list, but you can't put anything in nil
15:29	ticking_	I think a lot of bugs could be prevented if (conj [] nil) would be the identity
15:29	godd2	ticking_ perhaps, but you might also introduce other bugs
15:29	ticking_	,(conj nil 1)
15:29	ticking_	you think so ? ;P
15:29	clojurebot	(1)
15:30	ticking_	godd2: nil is the end of seqs as well as the empty map
15:30	godd2	,(cons nil 1)
15:30	clojurebot	#<IllegalArgumentException java.lang.IllegalArgumentException: Don't know how to create ISeq from: java.lang.Long>
15:31	ticking_	at least when it comes to operations that take them
15:31	ticking_	,(cons 1 nil)
15:31	clojurebot	(1)
15:31	godd2	,(cons '() 1)
15:31	clojurebot	#<IllegalArgumentException java.lang.IllegalArgumentException: Don't know how to create ISeq from: java.lang.Long>
15:32	ticking_	,(cons 1 '())
15:32	ticking_	conj and cons have reverse arguments
15:32	ticking_	godd2: yeah, but I wonder how we'd code if we didn't live in the constant fear of a nullpointer exception like the haskellers
15:32	clojurebot	(1)
15:32	AimHere	Maybe we'd code like the haskellers
15:33	godd2	ticking_ well I mainly code in Ruby, so I don't have that fear ;)
15:33	ticking_	AimHere: is that good or bad in you opinion :D
15:44	ticking_	godd2: A nice side effect would be that map could filter and assoc could dissoc, so no longer a need for the non existent dissoc-in
15:44	ticking_	godd2: the biggest downside I see is that (assoc [0 1 2] 1 nil) is inefficient in the current vector implementation
15:44	borkdude	can you collect "normal" args in a list like (defn f [x y :as z] z)?
15:46	simon	Aloha!
15:47	simon	Im quite new to clojure and are writing a blackjack game, and I represent a hands value as a list of lists since Aces can be either 1 or 11. I wanna define a function that calculates the set of possible values of a set and needs a way to combine a lists of lists to all the different lists that can be combined from them.
15:48	simon	That is probably a bit confusing.
15:48	simon	But in explenation.
15:48	simon	[[10] [9] [10]] -> [[10 9 10]] , [[5] [1 11]] -> [[5 1] [5 11]], [[1 11] [1 11]] -> [[1 1] [1 11] [11 1] [11 11]]
15:48	andyf	Cross product, or Cartesian product, are two names for that.
15:48	simon	Using the returned lists I wanna map a + reduce to get the different values.
15:49	simon	Yeah, im using cartesian product to generate my deck.
15:49	simon	But I dont relaly know how to do it for a list of lists, if that makes sense?
15:49	andyf	If you want a library to help with that, with source code you can look at, math.combinatorics has it.
15:50	simon	Okok, thanks.
15:50	andyf	Library in general: https://github.com/clojure/math.combinatorics The particular function: https://github.com/clojure/math.combinatorics/blob/master/src/main/clojure/clojure/math/combinatorics.clj#L117
15:51	andyf	That isn't necessarily a beginner-level function to read and understand easily, necessarily.
15:52	andyf	department of redundancy department -- the number of times I reuse words in a sentence that I don't re-read and edit is alarming.
15:52	simon	:)
15:55	simon	Sweet! Clojure is so neat. (apply ../cartesian-product (into () [[5] [1 11]])) -> ((5 1) (5 11))
15:55	TEttinger	that shouldn't work, should it?
15:55	TEttinger	.. is already a symbol
15:55	simon	clojure-blackjack.core> (apply combo/cartesian-product (into () [[1 11] [5]]))
15:55	TEttinger	(doc ..)
15:55	simon	((5 1) (5 11))
15:56	clojurebot	"([x form] [x form & more]); form => fieldName-symbol or (instanceMethodName-symbol args*) Expands into a member access (.) of the first member on the first argument, followed by the next member on the result, etc. For instance: (.. System (getProperties) (get \"os.name\")) expands to: (. (. System (getProperties)) (get \"os.name\")) but is easier to write, read, and understand."
15:56	simon	I didnt want to write out the library name.. :P
15:56	TEttinger	heh
15:57	TEttinger	,(for [a [5] b [1 11]] [a b])
15:57	clojurebot	([5 1] [5 11])
15:58	TEttinger	,(for [a [5] b [1 11]] (list a b)) ;for completeness
15:58	clojurebot	((5 1) (5 11))
15:58	simon	Hmm, im a bit confused, the (into () ..) bit is uneccecary. So how how does (apply ../cartesian-product [[1 11] [5]]) work?
15:58	simon	So you can apply functions to a sequence I guess and not just lists?
15:59	TEttinger	(into () [[5] [1 11]]) is the same as (list [5] [1 11]) and usually you don't need to ever use lists, vectors work in most of the same places
15:59	simon	Neato.
16:00	Ent_	(repeat 10)
16:00	andyf	simon: cartesian-product is written to take a variable number of sequences as arguments
16:00	simon	andyf: yeah, that I understand.
16:00	TEttinger	it's called the seq abstraction in a lot of stuff that talks about clojure
16:00	andyf	If it had instead been written to take a sequence of sequences, then apply would not be needed there.
16:00	simon	Its the apply that boggles my mind now. :)
16:01	Ent_	(take 1 (repeat "Hi"))
16:01	andyf	As maybe a simpler example, + is written to take a variable number of arguments:
16:02	andyf	,(+ 1 2 3 4 5)
16:02	clojurebot	15
16:02	Ent_	,(take 1 (repeat "Hi"))
16:02	clojurebot	("Hi")
16:02	Ent_	,(repeat 10)
16:02	clojurebot	(10 10 10 10 10 ...)
16:02	andyf	but you can't get a useful result calling it with 1 sequence:
16:02	andyf	,(+ '(1 2 3 4 5))
16:02	clojurebot	#<ClassCastException java.lang.ClassCastException: Cannot cast clojure.lang.PersistentList to java.lang.Number>
16:02	andyf	If you have a sequence of numbers, and want to add them up, one way is to use apply:
16:02	andyf	,(apply + '(1 2 3 4 5))
16:02	clojurebot	15
16:02	simon	My mental image of apply is that it just moves in the function into the list. i.e (apply str '(1)) => '(str 1) => (eval '(str 1))
16:03	simon	But from the implementation of apply its clear thats not how it works.
16:03	justin_smith	simon: ##(apply + 1 2 3 [4 5 6])
16:03	lazybot	⇒ 21
16:03	Ent_	,( #(+ %) '(1 2 3 4 5))
16:03	clojurebot	#<ClassCastException java.lang.ClassCastException: Cannot cast clojure.lang.PersistentList to java.lang.Number>
16:03	andyf	The implementation of apply is a bit lower-level code than most Clojure
16:03	andyf	for performance reasons.
16:04	andyf	There are other ways to write it that would look more like the way you described it in words.
16:05	andyf	If you have a number of arguments that is known when you are writing the code, there isn't much reason to use apply. It is necessary to use apply in cases where you have a sequence of arguments at run time, and you don't know how long it is.
16:07	simon	So, an implementation using apply is not idiomatic in this case you say?
16:07	Ent_	,( #(+ %) [1 2 3 4])
16:07	simon	http://pastebin.com/1C384QqL hand-value, at the end of the file.
16:07	clojurebot	#<ClassCastException java.lang.ClassCastException: Cannot cast clojure.lang.PersistentVector to java.lang.Number>
16:07	justin_smith	Ent_: what are you trying to do?
16:07	andyf	The example of (apply + '( 1 2 3 4 5)) I would never write that way except as an example. I would write it (+ 1 2 3 4 5)
16:08	Ent_	seeing if I can do `apply` without using apply
16:08	ticking_	(fold + coll) for really large cols ;)
16:09	justin_smith	yeah, you can use reduce instead of apply for things like +
16:09	justin_smith	,(reduce + [1 2 3 4 5 6])
16:09	clojurebot	21
16:09	justin_smith	ticking_: assuming by fold you mean reduce
16:09	kenrestivo	i wonder if the universe will explode if i do somthing to the effect of (async/go-loop [] (let [res (async/<! c)] (async/>! c (do-stuff res))))
16:09	Ent_	Ah that makes more sense
16:09	Ent_	thanks
16:10	ticking_	justin_smith clojure.reducers/fold
16:10	justin_smith	ahh
16:10	kenrestivo	especially since do-stuff can block
16:11	justin_smith	kenrestivo: locking vs. blowing?
16:11	kenrestivo	um, blowing?
16:11	justin_smith	up
16:11	kenrestivo	locking up, is what i've been experience
16:11	ticking_	simon, who said it was not idiomatic :)? sorry I missed the start
16:12	kenrestivo	i'm starting to think this message bus idea was very, very stupid.
16:12	kenrestivo	but it's hard to do this with discrete channels since there are circular relationships betwen the various components that need to communicate. a "network-like" bus with routing is optimal.
16:12	ticking_	btw does someone know of a clojure lib that takes two edn datastructures and returns a Om style assoc-in able diff?
16:13	kenrestivo	i feel like i'm trying to make core.async do stuff it was not designed to do.
16:14	justin_smith	kenrestivo: a good pattern is to take coordination vs. work that may block for a while, and put them in separate contexts, so there is always a quick response time from the coordinator
16:15	kenrestivo	that might work, a central router rather than a bus topology.
16:16	justin_smith	the router can even split into more than one parallel unit, as long as none of them lock up on long running tasks
16:17	justin_smith	also, Java Concurrency in Practice is a surprisingly good book, one of the items on the "Clojure reading list", worth looking at even if you aren't doing Java
16:17	kenrestivo	yeah, i feel like part of the problem is i do not have a deep understanding of what-all is going on under the hood in the jvm.
16:18	ticking_	I domt thi
16:18	ticking_	I dont think the people writing the jvm have that
16:19	Muonic	kenrestivo: I've only just started looking at core.async, but it doesn't feel well suited to functioning as a message bus
16:20	kenrestivo	thanks for the sanity check.
16:20	Muonic	mostly since multicasting doesn't fit in the model
16:20	kenrestivo	well there's pub/sub
16:20	kenrestivo	and mult/tap
16:22	SagiCZ1	whats the cure for a function that takes too many arguments?
16:22	ticking_	Yeah they seem to handle multicast reasonably well, even though some buffering is required
16:22	Muonic	i was thinking, in the sense you mayw ant multiple recievers to get the same message
16:22	Muonic	it becomes awkward trying to use mult/tab + pub/sub to acheive that effect
16:22	ticking_	Muonic, yeah that is what mult is for
16:24	ticking_	really? hm, but creating a chan and tabing with it seema like its equivalent to a bus subscribe right?
16:25	ticking_	SagiCZ1, depends, an opts map?
16:27	SagiCZ1	cfleming: it would be nice to have some support of (:require [... :reger [list-of-symbols]]) ... for example if i already have some there, i would like to have new ones added automatically with alt+enter.. and if the caret is in the list-of-symbols, it could show all available symbols for refering on ctrl+space
16:29	SagiCZ1	cfleming: and other cool thing would be a better support of variable extraction (default ctrl+alt+v) which doesnt work well and doesnt work at all in repl console.. just throwing it out since i always forget these
16:29	kenrestivo	ticking_: there's some ceremony with pub/sub, less so with mult/tap
16:30	kenrestivo	and the ceremony of pub/sub with mix becomes quite cumbersome. makes me think i'm Doing It Wrong.
16:30	cfleming	SagiCZ1: Yes, the better support for refer is definitely on the cards
16:31	cfleming	SagiCZ1: Do you have examples of the variable extraction not working?
16:31	SagiCZ1	it does work but i dont think i understand how can it help me.. it just replaces the selected sexp or value with the symbol 'value'.. i would expect it to be defined in the let or in root via def if there is no enclosing let
16:32	ticking_	kenrestivo: hm, yeah such a tight feedback loop with a channel feels a bit weird, but on the other hand if one imagines a channel as a queue it's not that strange
16:33	ticking_	feels like a infinite computation, but there are things hidden in our code everywhere just not as obvoous and scary
16:33	cfleming	SagiCZ1: When you do the extract, you have to select two things, the expression to extract, and where to extract it to
16:33	cfleming	SagiCZ1: At the point that you tell it to extract to, you'll get a new let binding
16:34	cfleming	SagiCZ1: If you select an existing let binding as the extract point, it will be added to that.
16:34	lxsameer	hey guys, how much clojure-android is slower than java on android ? is it noticeable ?
16:34	cfleming	SagiCZ1: I think what you're running into is a bug if you try to extract to the same point you're extracting from
16:35	SagiCZ1	cfleming: oh! it does work.. i didnt read the tooltip.. i thought it wanted me to select what i want to extract, which is something intellij does for java sometimes.. so i was choosing the lowest possible insertion which just replaces it with "value" .. but choosing enclosing let works fine
16:35	cfleming	SagiCZ1: Great - yeah, I need to fix that bug, it's almost never what you actually want to do but it's easy to do by mistake
16:36	SagiCZ1	cfleming: ok, but in repl the shortcut does nothing.. maybe its shadowed by something by my own settings
16:36	cfleming	SagiCZ1: I'll test that, it may be that it doesn't work - the REPL editor is subtly different in annoying ways
16:36	Ent_	@lxsameer I think it's quite slow. Atleast the time it takes for the app to start is quite long.
16:36	cfleming	SagiCZ1: If it doesn't work I'll fix for the next drop
16:37	lxsameer	Ent_: damn, thanks ,
16:37	SagiCZ1	cfleming: alright.. thanks for the info :)
16:37	cfleming	SagiCZ1: No worries!
16:37	Ent_	Yep, sure
16:39	cfleming	SagiCZ1: BTW for the extraction point selection I'm planning to add support for using ctrl-up/down to select only existing let bindings, since that's often what you want to do
16:40	SagiCZ1	cfleming: good idea, i am excited about this feature, i use it all the time in java
16:40	cfleming	SagiCZ1: Yeah, it's really useful
16:41	cfleming	SagiCZ1: I'll be adding extract method too sometime soon
16:41	cfleming	SagiCZ1: BTW inline binding works too, which I also use a lot
16:41	SagiCZ1	cfleming: what is that?
16:42	cfleming	SagiCZ1: If you no longer need a variable as a local binding, you can inline it and the uses will be replaced with the binding body, like inline variable in Java
16:42	SagiCZ1	cfleming: so thats basically extracting variable backwards?
16:43	cfleming	SagiCZ1: exactly
16:43	SagiCZ1	cfleming: hey this is way cool, i didnt know about this one, never used it.. smart
16:44	SagiCZ1	this will save some time too\
16:50	justin_smith	Ent_: some folks have addressed the startup time on android issues by compiling clojurescript (which has minimizing / tree shaking compilation via google closure)
16:51	Ent_	justin_smith: Oh. Guess the video I saw discussing it is now outdated.
16:54	justin_smith	oh, oops, meant to address that to lxsameer
16:55	lxsameer	justin_smith: clojurescript ? I thought we use clojure itself
16:56	justin_smith	lxsameer: the point is clojurescript can load much faster / use less of the device's ram
16:56	justin_smith	(though it won't likely perform as well for a long running / computation heavy process, but that isn't the only kind of process you have in a mobile app)
17:00	mfikes	lxsameer: Sam Beran has been investigating this. It involves ClojureScript -> JS -> Java bytecode -> Dalvik. I put together a little repo making it easy to try the sequence up to the Java bytecode: https://github.com/mfikes/cljs-cl
17:02	mfikes	lxsameer: I was exploring whether Sam's approach can also be used to make "Clojure" command-line apps that run with low start-up time
17:04	Ent_	mfikes: Would you say as it stands, clojure-android is decent for making apps?
17:05	mfikes	Ent_: I don't have any real experience with it. I've been focusing on ClojureScript on iOS.
17:05	arohner	I have lein fighweel finally working, but now how do I make the (Om) page re-render?
17:05	Ent_	ok
17:05	arohner	...re-render when fighweel determines that the code reloads, that is
17:07	mfikes	Ent_: Sam Beran's approach resulted in ridiculously fast launch time, FWIW. (I can't recall, but I think it was on the order of 100 ms or so.)
17:08	Ent_	mfikes: Cool. Will have a look at it.
17:09	mfikes	Ent_: His tweet about it: https://twitter.com/samberan/status/523929208595025920
17:10	sameerynho	justin_smith: clojurescript ? I thought we use clojure itself
17:12	Ent_	mfikes: Thanks. going through google results for Sam & clojure-android stuf
17:13	mfikes	Ent_: I bet the real challenge with Sam's approach is host interop with the Android stuff. For example, with the command line stuff, I had to do this funky call to print (via JS into Java): https://github.com/mfikes/cljs-cl/blob/master/ClojureScript/print-fibs/src/print_fibs/core.cljs#L6
17:16	Ent_	mfikes: Given that Dalvik VM is different from JVM, is there any other way to do it? I wonder if we just have to sit down and reimplement the whole thing.
17:17	mfikes	Ent_: Perhaps you could embed a JavaScript engine in our Android app. That's what I do on iOS.
17:19	mfikes	Ent_: Or wait for Clojure to get faster (tree shaking, or whatever they are doing in the fastload branch?)
17:22	Ent_	mfikes: Is the overhead of embedded JS engine within acceptable range or are you still working on optimising it?
17:28	mfikes	Ent_: It is fine on iOS. There's the phase where it parses and loads the JS and this takes 386 ms (I think this was on an iPod touch). That will only get faster. After that, the CPU and memory effects during normal app usage haven't been something I've been able to notice, when comparing to other native apps I've made.
17:34	justin_smith	mfikes: as I understand it fastload is just lazy about loading definitions (and ends up being slower for longer processes because it needs to check whether things are loaded before running them)
17:35	justin_smith	mfikes: arrdem can tell us more about the details, but simplistically speaking since eval is defined to be present in clojure at runtime, you need a modified language definition to get tree shaking that works properly.
17:37	mfikes	justin_smith: Interesting dilemma. I have no eval calls anywhere in any of my application-level code.
17:39	mfikes	justin_smith: I guess I like all of the flexibility during dev, but it would be interesting to have all sorts of semantics-bending whole-program optimizations for deployment. But everything is fast enough for me. Simpler is better :)
17:44	SagiCZ1	when i call (take-while pred (iterate ... )) the pred is called twice before calling fn in iterate.. is that because of chunking?
17:44	SagiCZ1	the function i iterate can never return nil.. but the predicate sometimes gets nil as an argument.. i dont understand how is that possible
17:47	SagiCZ1	cant replicate it on a simpler example
17:48	AimHere	So presumably the problem is something to do with whatever's in the ellipsis
17:49	AimHere	What' the function in the iterate?
17:49	SagiCZ1	it just returns an updated vector.. nothing fancy
17:49	SagiCZ1	the predicate checks whether the vector passes a condition
17:50	SagiCZ1	take-while:(0.5893322273289112 -0.014178434390894584 0.8908398415838613)
17:50	SagiCZ1	iterate:(0.5893322273289112 -0.014178434390894584 0.8908398415838613)
17:50	SagiCZ1	take-while:(0.5788656395366827 -0.11356364514133756 0.8944496094541826)
17:50	SagiCZ1	take-while:(0.5893322273289112 -0.014178434390894584 0.8908398415838613)
17:50	SagiCZ1	take-while:nil
17:52	SagiCZ1	i dont get it
17:53	AimHere	Again, not enough info to go on
17:53	SagiCZ1	the predicate gets called when its not supposed to
17:54	SagiCZ1	or maybe i dont understand how this construct works
17:54	SagiCZ1	iterate should create lazy seq of elements.. which get passed to the predicate in take-while as one argument right?
17:54	AimHere	Yes
17:55	AimHere	What happens if you '(take 100 (iterate inc ..))'?
17:55	AimHere	Is there a nil thrown up ever?
17:55	SagiCZ1	nope
17:55	SagiCZ1	that one works fine
17:56	AimHere	Is the predicate recursive?
17:56	SagiCZ1	the predicate is #(neg? (first (mmult (trans %) point class)))
17:58	SagiCZ1	so strange
17:58	justin_smith	and trans gets nil as an arg?
17:59	SagiCZ1	yes.. after random number of iterations
17:59	SagiCZ1	but (take 100 ... ) works
18:00	SagiCZ1	feels like all of my code is correct but the take-while iterate logic is acting up
18:01	justin_smith	iterate and take-while are really extensively used and debugged...
18:02	SagiCZ1	what can force the take-while predicate to be evaluated several times in a row without the iterated fn being called?
18:02	justin_smith	I think it's more likely your tracing logic is flawed than that happened
18:02	SagiCZ1	its like: iterate->pred->iterate->pred->iterate->pred->pred->pred->exception
18:03	SagiCZ1	yeah ok, its just println
18:03	SagiCZ1	not sure how to debug it
18:03	SagiCZ1	maybe i will dust off the debugger
18:15	SagiCZ1	ok, it was my mistake of course.. the nil was coming from the initial iterate value
18:27	SagiCZ1	how would i return the first positive number in collection?
18:28	SagiCZ1	[-4 -8 -9 -5 -9 10 13 46] --> 10
18:28	SagiCZ1	i think there might be a better way
18:28	SagiCZ1	,(last (last (take-while #(some neg? %) (partition 2 1 [-4 -8 -9 -5 -9 10]))))
18:28	seangrove	What are the advantanges of reified, first-class namespaces, and the disadvatanges of cljs' current implementation?
18:28	clojurebot	10
18:28	seangrove	dnolen_: ^^ just in general
18:28	seangrove	Nothing too detailed
18:29	hipsterslapfight	SagiCZ1: `(first (filter pos? collection)` maybe?
18:29	SagiCZ1	thats way better, thanks
18:29	SagiCZ1	(inc hipsterslapfight)
18:29	lazybot	⇒ 1
18:30	hipsterslapfight	np
18:30	AimHere	I keep thinking that 'some' does that job, but it just gives the truthy value instead
18:32	Frozenlock	AimHere: That's because of 'pos?', not 'some'.
18:32	Frozenlock	,(some #(when (pos? %) %) [-4 -8 -9 -5 -9 10 13 46])
18:33	clojurebot	10
18:33	AimHere	Yeah, I know
18:33	AimHere	You can write the predicate to make some do that job, but then the first/filter dance becomes prettier
18:36	Frozenlock	That's kind of sad in a way... I would love to have filter/some behave in the same way.
19:08	justin_smith	Frozenlock: instead of when, you can use and (which helps emphasize it's a value, not a side effect)
20:24	justin_smith	SagiCZ1: I just realized there is this one too: ##(first (drop-while neg? [-4 -8 -9 -5 -9 10 13 46]))
20:24	lazybot	⇒ 10
20:26	ajmccluskey	Anyone know an easy way to print a transient map the same way a regular one is printed?
20:27	rhg135	i guess you could redefine print-method
20:27	ajmccluskey	rhg135: right. I guess I'm really checking if there's an existing function or something quick and dirty.
20:28	rhg135	not that im aware of, ajmccluskey
20:28	rhg135	but wait for them smart folks
20:28	ajmccluskey	haha, thanks :)
20:30	rhg135	ajmccluskey: also this is quick and very dirty
21:52	justin_smith	http://stackoverflow.com/questions/27736719/core-async-machine-that-loops-until-a-fx-returns-true what this guy is doing looks smelly, but I don't know the right answer
22:19	kenrestivo	a weird side-effect of using core.async is, i've noticed, it pushes me toward writing imperative code. loops, and so on.
22:19	kenrestivo	looks like that guy got the disease too. "oh, i'll just busy-wait"
22:20	kenrestivo	i find the more i use core.async, the less functional my code is.
22:20	kenrestivo	maybe i should get on the transducer tip.
22:21	jonasen	kenrestivo: which isn't surprising since core.async isn't a functional construct
22:21	AWizzArd	justin_smith: why did this guy not install an onload handler for the body? This function gets called by the JSVM when the body was loaded.
22:21	AWizzArd	<body onload="myFunction()">
22:22	kenrestivo	i'm tempted to say "use om or reagent", but that's too dismissive and proabbly unnecessarily heavyweight for what he's trying to do.
22:27	kenrestivo	justin_smith: it kind of begs the question: "why or what is creating that element, and why can't it do that (.start f) once it does?
22:30	rhg135	core.async is meant to do the communication
22:30	rhg135	hence the c in csp