#clojure – 2015-11-29

2015-11-29

00:36	TEttinger	,(expt 2N 18446744073709551616N)
00:36	clojurebot	#error {\n :cause "Unable to resolve symbol: expt in this context"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.RuntimeException: Unable to resolve symbol: expt in this context, compiling:(NO_SOURCE_PATH:0:0)"\n :at [clojure.lang.Compiler analyze "Compiler.java" 6704]}\n {:type java.lang.RuntimeException\n :message "Unable to resolve symbol: expt in this co...
00:37	TEttinger	right, I imported the numeric tower lib
00:39	TEttinger	I think that's uh a rather large number
00:46	Jinxit	is there any good online quick start to clojure? I'm familiar with functional programming
00:46	Jinxit	but not really any lisps
01:05	TEttinger	Jinxit: brave clojure, 4clojure exercises, clojuredoc
01:05	TEttinger	~brave clojure
01:05	clojurebot	Titim gan éirí ort.
01:05	TEttinger	clojurebot: brave is http://www.braveclojure.com/
01:05	clojurebot	c'est bon!
01:06	justin_smith	Jinxit: also, http://conj.io is a good reference to the core language of clojure, and most functions there should be somewhat familiar if you have used functional languages
01:06	TEttinger	good ol' grimoire
01:07	Jinxit	alright, thanks all
02:05	Seraf	Hello everyone. I'm a bit loss: I'm trying to group-by date my results : http://pastebin.com/BhMLZXJw I'm using cljs-time. The problem is that I can't group-by directly on my data as the datetime is too much precise so I would like to convert it to YYYY-MM-DD to have a "logic" group-by. So I need to transform my map before applying a group by on it (but I also don't want to loose the original data as I would like to use it).
02:06	Seraf	I tried a :date_finished on the group-by, but if I apply my cljs-time function on the keyword, it isn't a function anymore then it doesn't work :(
03:51	douglarek	how can i stop an execution in cider repl ?
03:51	douglarek	such as : i entered (cycle [1])
03:54	Seraf	Hello everyone. I'm a bit loss: I'm trying to group-by date my results : http://pastebin.com/BhMLZXJw I'm using cljs-time. The problem is that I can't group-by directly on my data as the datetime is too much precise so I would like to convert it to YYYY-MM-DD to have a "logic" group-by. So I need to transform my map before applying a group by on it (but I also don't want to loose the original date as I would like to use it further).
04:43	ben_vulpes	how would one go about passing &args to a downstream function in such a way that it doesn't wrap them in a list itself?
04:55	TEttinger	ben_vulpes: apply
04:56	TEttinger	,((fn [& args] (clojure.string/join "," args)) "hey" "clojure" "people")
04:56	clojurebot	"hey,clojure,people"
04:57	TEttinger	,((fn [& args] (apply str args)) "hey" "clojure" "people")
04:57	clojurebot	"heyclojurepeople"
04:57	ben_vulpes	TEttinger: myeah, i got hung up on non-optional args.
04:58	ben_vulpes	was shooting for (apply (partial my-func arg1) [:optional :args])
04:59	TEttinger	do what I do in this situation
04:59	TEttinger	hope justin_smith is awake
05:00	ben_vulpes	hahahaha
05:00	ben_vulpes	's not a big deal.
05:38	Glenjamin	Seraf: group-by takes a function, have that function do the date formatting
05:54	Seraf	Glenjamin, thanks for the answer, I finally found a solution, it's working well
06:59	donbonifacio	why is equality with persistent data structures so efficient? Why is there no need to perform a deep compare?
07:35	kungi	donbonifacio: because they are immutable. therefore no deep compares are required
07:36	donbonifacio	I'm checking out the core, and deep compares may happen
07:36	donbonifacio	it's very optimized true, but it can happen
07:58	TimMc	One really simple case is where you pass someone a nested map, they may or may not do something to it, and they pass you back another version of it and you want to compare some of the submaps.
07:58	TimMc	or just the whole thing, I guess
07:58	TimMc	If a map hasn't been altered, the object identity is the same, so an equality check is really fast.
07:59	TimMc	In Java-land, you'd probably want to do a deep copy to make sure mutation is controlled, and then you'd lose that shortcut.
08:03	beaky	hello
08:03	beaky	how do i printf a list
08:03	beaky	or vector or map
08:05	TimMc	beaky: Not re what precisely you're having trouble with. What's a sample input and output that you want?
08:05	TimMc	*Not sure
08:05	beaky	,(printf "%s\n" [])
08:05	beaky	i wat that to be []
08:05	clojurebot	[]\n
08:05	beaky	oh
08:05	beaky	nvm :D
08:05	beaky	,(printf "%s\n" [1 2 3])
08:05	clojurebot	[1 2 3]\n
08:13	TimMc	beaky: Do you know the pr/print distinction?
08:22	beaky	TimMc: no whats the diference
08:22	beaky	,(pr [1 2 3])
08:22	clojurebot	[1 2 3]
08:23	beaky	,(pr "1 2 3")
08:23	clojurebot	"1 2 3"
08:23	jeaye	^ that
08:23	beaky	(print "1 2 3")
08:23	beaky	,(print "1 2 3")
08:23	clojurebot	1 2 3
08:23	beaky	ah
08:24	beaky	no " in print
08:27	jonathanj	can i iterate an Iterable<X> in Clojure?
08:30	Bronsa	you can reduce over it
08:59	justin_smith	ben_vulpes: (apply str "a" ["b" "c"])
08:59	justin_smith	,(apply str "a" ["b" "c"])
08:59	clojurebot	"abc"
09:11	TimMc	beaky: In general, print prints the contents of data, and pr prints in a way that can be read back through read-string.
09:12	TimMc	Strings are the only thing that comes to mind at the moment as printing differently.
09:13	TimMc	beaky: It's not just the quotes; "a\nb" will print as a and b on two lines but pr as six chars: "a\nb"
09:14	justin_smith	,(pr (map char (range)))
09:14	clojurebot	(\
09:14	justin_smith	,(print (map char (range)))
09:14	clojurebot	(
09:14	justin_smith	hmmm
09:15	justin_smith	,(print (map char (range (int \a) (int \z)))
09:15	clojurebot	#<RuntimeException java.lang.RuntimeException: EOF while reading>
09:15	justin_smith	,(print (map char (range (int \a) (int \z))))
09:15	clojurebot	(a b c d e ...)
09:15	justin_smith	,(pr (map char (range (int \a) (int \z))))
09:15	clojurebot	(\a \b \c \d \e ...)
09:15	justin_smith	,(str (map char (range (int \a) (int \z))))
09:15	clojurebot	"clojure.lang.LazySeq@9013fb8c"
09:16	justin_smith	sad trombone
09:20	Bronsa`	j
09:24	beaky	ah
09:30	wmealing	this is probably a rookie mistake, I'm a little stuck on how to ensure that when mapping over and ordered list, that the returned data is in the same order.. my example is here
09:30	wmealing	http://hastebin.com/cihewahuhu.pl
09:31	wmealing	i had tried with an array-map (see line 16)
09:31	justin_smith	wmealing: "Application Error"
09:31	justin_smith	wmealing: map doesn't ever change the order relative to the input
09:32	justin_smith	wmealing: it's not map changing the order, it's array-map
09:32	wmealing	ok, so what.. or how should I be doing that ?
09:33	wmealing	i'm 100% sure this is my fault.. i know that
09:33	justin_smith	wmealing: if you need the data to be ordered, you shouldn't be using a hash-map or array-map. There is an insertion ordered map from flatland, flatland/ordered-map iirc.
09:34	justin_smith	wmealing: I was wrong, it's amalloy/ordered https://github.com/amalloy/ordered
09:34	justin_smith	wmealing: it might seem like array-map would have preserved the order, but if you conj onto an array-map of a certain size, it returns a hash-map
09:35	wmealing	which is likely what i'm seeing there
09:35	justin_smith	yes, that is exactly what's happening - note how the processing happens in order, verified by your printing
09:35	justin_smith	it's the storage that goes out of order
09:36	wmealing	is there a better/alternative way to be doing what i'm doing
09:36	wmealing	i guess i could just pull them out in order when i extract them from the map
09:36	justin_smith	wmealing: an ordered map makes sense if you want to preserve insertion order and also look things up by key
09:37	wmealing	thanks justin_smith.
09:37	justin_smith	wmealing: another alternative would be mapping the months to indexes in a vector via a hash-map, then putting the data in a vector by those indexes, but of course that is less convenient and direct
09:38	wmealing	right. just one of the choices i have to make
10:26	Glenjamin	i'd probably suggest a sorted-map here
10:26	Glenjamin	rather than relying on correct insertion, since the keys do have a well-defined sort order
10:28	Glenjamin	some combination of (sorted-map-by), a map of month->index and (compare) would do it
10:36	jonathanj	is there some way i can use with-open with a collection of streams?
10:37	jonathanj	something like: (with-open [streams (fetch-multiple [uri1 uri2 uri3])] ...)
10:49	justin_smith	jonathanj: a multi-arity with-open that expands to nested with-open calls would be a nice intermediate macro writing challenge
11:06	jonathanj	nested?
11:07	jonathanj	i'm not sure they have to be nested, they just have to be unrolled, surely?
11:07	justin_smith	with-open manages a single stream
11:07	justin_smith	what do you mean by unrolled?
11:07	jonathanj	with-open calls close on all of the bindings
11:08	justin_smith	(doc with-open)
11:08	clojurebot	"([bindings & body]); bindings => [name init ...] Evaluates body in a try expression with names bound to the values of the inits, and a finally clause that calls (.close name) on each name in reverse order."
11:08	justin_smith	oh, it takes multiple streams anyway, never mind
11:09	justin_smith	so no, you can't do it with a macro
11:09	justin_smith	unless the collection is known at macro expansion time, which is part of the compilation process
11:09	justin_smith	so you could do it with eval, but that's gross
12:19	Glenjamin	$source with-open
13:32	justin_smith	Glenjamin: I could see doing it with a recursive function that takes streams as a list and an N arg function to apply to the streams, and for each recursive call it creates a try/catch/finally for the next stream and adds it to the list for applying...
15:35	devn_	I can't brane good today.
15:36	devn	I am using environ, and I have a function that pulls values out of the environ map.
15:37	devn	This function raises if a particular configuration value is not found.
15:37	devn	I'm thinking that I'd like to make a new type of map that does this, so I don't have to call the function
15:38	devn	so (get environ-map :foo) will throw if :foo doesn't exist
15:38	justin_smith	easier to write the alternate get, but sure
15:38	devn	well, i'd like to destructure, for example
15:39	devn	(let [{:keys [a b c]} environ-map] ...)
15:39	devn	justin_smith: what's the best way to do what im trying to do here? do i want to reify and define get on this particular map instance?
15:39	devn	or?
15:39	clojurebot	or is there another way to upload it
15:41	justin_smith	devn: yeah, you could use reify and implement all the relevant methods, referring to the original object for everything but get, where you have the throw?
15:41	justin_smith	devn: but maybe it would be simpler to use prismatic/schema to check the map when it's created?
15:43	devn	justin_smith: maybe...
15:43	devn	or maybe try out structural typing
15:43	devn	https://github.com/marick/structural-typing
15:44	devn	justin_smith: when you say "all the relevant methods"
15:44	justin_smith	devn: interesting, looks like it tries to do some of the same stuff prismatic/schema tries to do
15:45	devn	i should just need a couple of arities for `get` (m k) (m k not-found), and `get-in` right?
15:45	justin_smith	devn: by that I mean check out (supers {}) or (supers (class {})) or whatever it is, and get all their methods, and implement them all by delegating to your hash-map
15:45	justin_smith	or just implement only and exactly the methods you plan on anyone ever calling, I guess
15:46	devn	yeah, that seems gross, ive done that before by using potemkin
15:46	devn	to use deftypefn i think it's called
15:47	devn	justin_smith: i think i like this structural typing business quite a bit
16:05	kenrestivo	is there a cond with fallthrough?
16:05	kenrestivo	ah, nevermind :else