#clojure – 2015-12-10

2015-12-10

00:09	amalloy	well it wasn't exactly a real question, so much as a social commentary on your asking how people remember things
00:51	TEttinger	ok, that's an exciting outcome...
00:52	TEttinger	I am evaluating YourKit, justin_smith I'm blaming you if it isn't fantastic, but it seems rather great so far
00:53	TEttinger	found that in this java lib that is intended to be used to do heavy work so clojure doesn't have to... 83% of CPU time for this test is spent on one line. it is not a small test.
00:54	TEttinger	the line doesn't seem like it should be that slow. it converts a type-specialized resizable array of short values to a "real" array of short values
00:55	TEttinger	and internally all that does is System.arraycopy
00:57	TEttinger	so... does anyone know if having low memory available to the program would explain the array copy being slow?
01:39	wolgo	Hi. I want to learn clojure. I know some other languages. I learn best by just hacking away but is there a book that the community recommends to supplement my learning? I am starting a new job soon and part of my duties will include writing production quality clojure code. Thanks for helping me.
01:56	TEttinger	wolgo: there's brave clojure, several other good physical books
01:56	TEttinger	~brave clojure
01:56	clojurebot	Titim gan éirí ort.
01:56	TEttinger	~brave
01:56	clojurebot	brave is http://www.braveclojure.com/
02:39	wolgo	TEttinger: okay cool, I have been perusing that one
02:40	wolgo	TEttinger: thank you
02:40	TEttinger	hope you find it useful!
02:47	BRODUS	say i want each of my list items to be an argument to a function call, is there a macro that will do that?
02:48	amalloy	(doc apply)
02:48	clojurebot	"([f args] [f x args] [f x y args] [f x y z args] [f a b c d ...]); Applies fn f to the argument list formed by prepending intervening arguments to args."
02:50	BRODUS	(apply (map identity) '(1 2 3 4))
02:50	amalloy	well, close. you mean (apply map identity '(1 2 3 4))
02:50	amalloy	or, well, you don't even mean that, because that's just (map identity 1 2 3 4), which doesn't work
02:51	BRODUS	ok i think i get it
02:52	opqdonut	,(apply map + [[1 2 3] [4 5 6] [7 8 9]])
02:52	clojurebot	(12 15 18)
03:33	slawo	hey everyone, quick question about profiling a clojure app
03:33	slawo	I got myself visual vm open
03:33	slawo	connect to a repl session
03:34	slawo	and cpu-sample while I run (dotimes [n 1e8] (my-thing))
03:35	slawo	visual vm starts producing data alright
03:35	TEttinger	criterium is best for benchmarking
03:35	opqdonut	yeah but profiling /= benchmarking
03:35	TEttinger	yeah
03:36	TEttinger	not sure what the question would be
03:36	slawo	but of course the functions with most self-time are my-ns.$eval12334$fn__3434.invoke()(
03:36	opqdonut	jvisualvm is nice, but you usually need to filter out lots of classes/packages to get a result you can actually interpret
03:36	opqdonut	slawo: if (my-thing) is an actual function in an actual namespace, it will show up as my-ns$my-thing or so
03:37	opqdonut	the evalXXXXX basically refers to the line you typed into your repl
03:37	slawo	cool
03:37	slawo	any way to get those fn__3434334’s sorted?
03:38	slawo	I assume they are inner functions
03:38	opqdonut	they're closures yeah
03:38	slawo	any way to identify which ones?
03:38	slawo	like attaching metadata to them or something
03:38	riceandbeans	brave clojure is confusing the hell out of me
03:39	opqdonut	slawo: sorry, no ideas there. in my experience the profiles for actual clojure programs are quite readable because you tend to have lots of small named functions
03:40	slawo	so it’s not common to use closures in clojure?
03:41	riceandbeans	what is a closure?
03:41	slawo	I mean, if I have to spell out every single reducer function instead of inlining with #() or (fn foo []) … clojure loses some of its appeal, no?
03:41	amalloy	slawo: look more closely at the names of the functions. they'll indicate what top-level var they're apart of
03:41	slawo	amalloy: cool, so the numbers mean something?
03:41	amalloy	,(class ((fn foo [] ((fn inner [] inner)))))
03:42	clojurebot	sandbox$eval25$foo__26$inner__27
03:42	amalloy	not really, no
03:42	amalloy	but look at this classname
03:42	slawo	let me see…
03:42	amalloy	,(defn f [] ((fn foo [] ((fn inner [] inner)))))
03:42	clojurebot	#'sandbox/f
03:42	amalloy	,(class (f))
03:42	clojurebot	sandbox$f$foo__53$inner__54
03:43	amalloy	you can see what top-level var owns the lambda, and how many nested lambdas "deep" it is, and additionally if any of those are named you can see their names
03:45	slawo	let me see if I can name them
03:48	slawo	amalloy: any idea what a …$G__3434_1234.invoke() is?
03:48	slawo	the G prefix is different from a fn prefix
03:49	amalloy	,(class #(inc))
03:49	clojurebot	#error {\n :cause "Wrong number of args (0) passed to: core/inc--inliner--4246"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "clojure.lang.ArityException: Wrong number of args (0) passed to: core/inc--inliner--4246, compiling:(NO_SOURCE_PATH:0:0)"\n :at [clojure.lang.Compiler analyzeSeq "Compiler.java" 6891]}\n {:type clojure.lang.ArityException\n :message "Wrong numb...
03:49	TEttinger	probably a symbol
03:49	luma	it's a symbol from (gensym)
03:49	amalloy	,(class #(+ 1 2))
03:49	clojurebot	sandbox$eval128$fn__129
03:49	amalloy	yeah, what luma said
03:49	TEttinger	,(let [m# 2] (class m#))
03:49	clojurebot	java.lang.Long
03:50	TEttinger	,(let [m# #(+ %1 2)] (class m#))
03:50	clojurebot	sandbox$eval179$m_SHARP___180
03:50	TEttinger	nooo....
03:50	TEttinger	autogensym doesn't do it?
03:50	TEttinger	,(gensym +)
03:50	clojurebot	clojure.core$_PLUS_@378fdfe1207
03:51	TEttinger	,(gensym ++++)
03:51	clojurebot	#error {\n :cause "Unable to resolve symbol: ++++ in this context"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.RuntimeException: Unable to resolve symbol: ++++ in this context, compiling:(NO_SOURCE_PATH:0:0)"\n :at [clojure.lang.Compiler analyze "Compiler.java" 6704]}\n {:type java.lang.RuntimeException\n :message "Unable to resolve symbol: ++++ in this co...
03:51	amalloy	TEttinger: # only does anything inside `
03:51	TEttinger	,(gensym #(+ 1 2))
03:51	clojurebot	sandbox$eval253$fn__254@22ed95cd257
03:54	slawo	all of my slow spots are $G__somethings :)
03:55	jonathanj	so revisiting the repl conversation from several hours ago, it would be pretty cool if you could put nREPL behind SSH with only public key auth
03:55	amalloy	well, figure out what they're inside of
03:55	amalloy	some macro is generating functions
03:55	ashwink005	has anyone worked with clout?
03:56	ashwink005	is there any support for regex?
04:10	BRODUS	I want to convert a list to a hashmap where every item in the list is a key in the hashmap. is there a better way to do this than 'frequencies' ?
04:11	MJB47	depends what you want the values to be
04:11	BRODUS	doesn't matter
04:12	MJB47	then i dont see why you want a hashmap?
04:12	luma	why do you want a hashmap then?
04:13	BRODUS	i want to later filter another list based on the items presence in the hashmap
04:13	luma	use a set
04:13	MJB47	why cant you do that with a vector or set?
04:13	MJB47	or even the list
04:14	slawo	prismatic have https://github.com/Prismatic/plumbing/blob/master/src/plumbing/core.cljx#L86 this for this purpose
04:14	BRODUS	using a set makes sense
04:15	slawo	btw. my mysterious G__ appears to be the function dispatch of defprotocol
04:17	slawo	shame functions in defprotocol appear as fn_123213, even though they clearly are named
04:19	slawo	and shame that function dispatch based on protocols is the slowest of my system… I’ll check if I can get rid of the protocol and call foo-to-this foo-to-that if I happen to know the types
04:30	noncom	slawo: i never use protocols though many say them are good things.. i don't mind, but i just don't use them
04:31	slawo	noncom: they are brilliant for polymorphism
04:31	slawo	but you better not have any polymorphism in your cricical paths :)
04:32	noncom	yeah! well, i deal with polymorphism differently, mostly avoiding it
04:33	slawo	noncom: but it’s tempting to use language facilities, no? :)
04:34	noncom	slawo: not really..
04:34	clojurebot	excusez-moi
04:34	noncom	slawo: such a dispatch can be explained by a lesser set of "facilities"
04:35	Trioxin	I was speculating on this yesterday to someone but I need some clarification. I'd like to use Clojure with nwjs so that I can make my clojure GUIs with HTML5. I should be able to just load a clojure jar in the chromium wrapper as an applet right? And also communicate between the applet and code on the page? I've never made an applet.
04:35	noncom	like, reduced to simple operations, without getting a whole other paradigm into the business
04:35	noncom	slawo^
04:36	slawo	noncom: well at the lowest level I agree, but once I start putting things together, it helps to think of them as ‘foos-of-a-kind’
04:36	noncom	slawo: maybe, maybe.. but in such cases i just group them in {}s
04:37	noncom	see, no garbling of names, no hassle behind the scene..
04:37	slawo	I suppose :)
04:37	slawo	erlang is a bit like that no?
04:37	noncom	yeah
04:37	noncom	a bit :)
04:37	slawo	my_thing = [:type_of_thing what ever else]
04:38	slawo	and then you just match on the first field :)
04:38	slawo	everywhere :)
04:40	noncom	slawo: yep, like that too
04:44	noncom	Trioxin: how do you want to distribute your app? from what i know, the chromium wrapper allows for getting browser functionality inside, say, a java app, is this what you want?
04:46	Trioxin	noncom, in nwjs, since it's meant for creating desktop apps, things like xss and other system protections are disabled. I intend to use clojurescript and HTML5 code in the dom and the applet will do all the heavy lifting.
04:47	noncom	then what's the problem?
04:47	noncom	it looks pretty straightforward...
04:48	noncom	you won't need an applet if the wrapper is about wrapping the browser in java app
04:48	noncom	i think you'll simply need a java app
04:49	Trioxin	noncom, problem is I don't think I can just run any old jar as an applet and I'm not sure what the procedure for that would be with clojure. I see these http://juliangamble.com/blog/2011/11/27/applets-in-clojure-and-counterclockwise/ and this https://en.wikibooks.org/wiki/Clojure_Programming/Examples/Creating_an_Applet . I intend to load the jar in the browser, not wrap a browser in clojure.
04:51	Trioxin	noncom, I can follow those links I suppose but it's telling me that I won't be able to properly debug (In one example) and that I have to take extra steps to use an repl in the other. I'm wondering if there's an easier way.
04:52	noncom	i don't really get it. you want a java app with HTML gui but applets are forbidden now in browsers, so you're using a bare browser engine to work around the security limitations and run your applet in it. BUT you want to run the applet in an actual browser still!
04:52	Trioxin	noncom, also I think those examples might assume I'm trying to display things using my jar. It's just going to be doing system work.
04:53	Trioxin	noncom, nwjs.. not a browser
04:54	noncom	okay, but from what i see on their page, is like, nwjs will be employed as a plugin for your java app. not like your java app will be running inside nwjs, but vice versa
04:54	Glenjamin	clojurescript is the key point here
04:54	noncom	am i wrong?
04:54	Glenjamin	you said clojure initially, but then mentioned cljs
04:55	noncom	yeah, with clojurescript there's a tonn more variables
04:56	Trioxin	noncom, nwjs is a chromium wrapper with node that has node interop in the dom. I want to load my jar in the dom and communicate with the dom. For that requires an applet. I do plan to use cljs as well but my jar to perform systems operations.
04:57	noncom	hmmmm sounds convoluted ..
04:57	Trioxin	noncom, the jar needs to be in the "Browser," a browser that doesn't have limitations on java and I don't wish for my jar to have it's own GUI. nwjs can take care of that. From an applet I can communicate with javascript or cljs on the page
04:58	noncom	i think it is very unfeasible to manipulate dom from java
04:58	Trioxin	I've seen that done before with Java applets but this is clojure and the examples I saw were creating GUIs with Java which I don't intend to do.
04:59	Trioxin	noncom, they interop
04:59	Trioxin	i could interop with node but I don't want a step in the middle
05:00	noncom	yes, i know.. but why don't you want to use clojurescript for that? you said that java could do system work, so why then involve it into dom alteration?
05:00	Trioxin	noncom, the GUI will enable the user to make use of the jar
05:01	Trioxin	i don't want to make my gui in clojure. I want to use nwjs for several reasons.
05:02	noncom	okay, i understand..
05:02	noncom	Trioxin: did you think about creating a clojure app that serves a web gui?
05:03	noncom	that would be far more straightforward
05:04	Trioxin	nwjs is very mature, serving a web gui in clojure would be code I don't have to write, and node/dom interop is baked into nwjs so that's always good.
06:14	BRODUS	has anyone else had trouble getting popup clojure documentation to work in emacs?
06:26	ashwink005	anyone used nginx?
06:42	ARM9	what's the easiest way to use antlr to generate a parser in a lein project?
06:47	yenda	people use lein template to make boot templates ?
07:45	jonathanj	why if i have something like: `(let [thrower #(throw %)] (future (try (throw (ex-info "Oh no" {})) (catch Exception e (thrower e))))` does the exception not actually get thrown?
07:46	jonathanj	`thrower` is invoked but apparently trying to rethrow that exception does nothing
07:46	justin_smith	jonathanj: you don't get the exception until you deref the future
07:48	jonathanj	What do you mean?
07:48	jonathanj	What do you mean by "get the exception"?
07:48	justin_smith	jonathanj: if an exception happens inside a future, you can deref the future to get the exception to throw. Otherwise it's a silent failure.
07:49	jonathanj	uh, okay, but in that code there i'm calling a function defined outside the future that rethrows the exception
07:49	jonathanj	that function is being called and the exception is well defined but apparently trying to rethrow it does nothing
07:49	jonathanj	and i'm not deferring the future, so why does rethrowing do nothing?
07:49	justin_smith	jonathanj: throws inside the future are handled differently
07:50	justin_smith	you don't see the exception unless you deref it
07:50	jonathanj	problem is that deref is blocking :\|
07:52	jonathanj	i tried to understand agents, but i'm not sure how to apply the "change the agent state" approach to mutable Java stuff
07:52	powered	what's the use for exceptions anyway outside of java interop?
07:52	justin_smith	jonathanj: since the bots don't let us play with exceptions, see this example: https://www.refheap.com/112543
07:52	jonathanj	powered: i dunno, to signal an exceptional state?
07:52	justin_smith	jonathanj: that's not what agents are for - send to an agent changes which object the agent holds, usually
07:53	jonathanj	justin_smith: yeah, that's the picture that was slowly making sense to me
07:53	justin_smith	powered: there's plenty of ways to make an exception happen without interop
07:54	justin_smith	jonathanj: I mean it's hypothetically possible to put a mutable java thing in an agent, and only send functions that poke its mutable state followed by returning the original object
07:54	justin_smith	but this isn't what agents are set up to do
07:54	justin_smith	jonathanj: definitely do not put mutable things in atoms or refs, because retries
07:54	jonathanj	yeah
07:54	powered	yes I guess network request etc has exceptions
07:55	justin_smith	,(+ 1 "hello") ; all sorts of things are erroneous
07:55	clojurebot	#error {\n :cause "java.lang.String cannot be cast to java.lang.Number"\n :via\n [{:type java.lang.ClassCastException\n :message "java.lang.String cannot be cast to java.lang.Number"\n :at [clojure.lang.Numbers add "Numbers.java" 128]}]\n :trace\n [[clojure.lang.Numbers add "Numbers.java" 128]\n [clojure.lang.Numbers add "Numbers.java" 3640]\n [sandbox$eval25 invokeStatic "NO_SOURCE_FILE" 0]...
07:55	jonathanj	exceptions have kind of got a bad rep, for reasons i don't fully understand
07:56	powered	because correct code doesn't encounter exceptions
07:56	powered	and exceptions as flow control mechanism isn't good either
07:56	jonathanj	without exceptions (or some notion of "a thing happened that was not success and now you had better deal with it") you end up with Go-style silliness
07:57	jonathanj	yeah, well the real world isn't always correct
07:57	jonathanj	if some user says "hey, use the certificate with alias X" and there is no such certificate in the keystore, what do you do?
07:57	powered	return nil
07:57	powered	I like the idea of pure functions returning something, not throwing exceptions
07:57	jonathanj	okay, so then the thing that was expecting a result now has to handle nil
07:57	justin_smith	nil is arguably worse than exceptions
07:58	jonathanj	and nobody knows there was an error
07:58	jonathanj	and eventually you get to a piece of code that says "hey, i can't add 1 to nil guys" and you are totally clueless as to what the hell lead you down this path
07:59	ARM9	that's what you get with dynamic typing, time to reinvent the monad
08:00	powered	I'd rather use if vs try catch
08:00	jonathanj	powered: well they're not really comparable
08:00	jonathanj	powered: you can't accidentally ignore an exception
08:01	jonathanj	if you assume code always returns a non-error value it means you can just write what you mean and the "good" code path is much cleaner
08:01	jonathanj	instead of littering it with return code checks
08:01	Glenjamin	if you use the maybe monad with do notation, you still can't tell where the Nothing came from
08:02	powered	yes, so you're saying if something goes wrong: fail right away
08:02	jonathanj	powered: that's usually the best course of action
08:02	Glenjamin	it's the best default imo
08:02	jonathanj	but if you don't want to do that, or you know how to recover, then you catch the exception and do the better thing
08:02	jonathanj	imo, that is a much better case than "always write all of the error handling all over your code"
08:06	jonathanj	justin_smith: i'm not really sure what actually suits my needs then
08:07	jonathanj	justin_smith: i don't want to block on a deref only to determine if there's an exception
08:07	jonathanj	so while i can use `realized?`, what if the exception hasn't occurred by the time i check if it's realized?
08:08	justin_smith	jonathanj: look at my paste - it's possible to ask if it's realized, also consider you could do something other than just a rethrow - you could send a message to some queue or channel indicating the error occurred, or even just log it
08:08	justin_smith	jonathanj: realized? means it stopped - and it should stop at some point right?
08:09	jonathanj	justin_smith: yes, but there is always the possibility that i call realized? one second before the exception occurs, so the question is when do i call realized?
08:10	justin_smith	it really depends what you are doing with that future. Maybe you should just log the error or put a status on a queue being watched somewhere.
08:10	jonathanj	justin_smith: a channel might be a possibility, can i put to a channel from another thread?
08:10	justin_smith	yes, core.async is pretty flexible about where stuff executes
08:11	jonathanj	justin_smith: so the reason i need the exception is because if there is an exception i need to communicate to the client (this is a service handling an HTTP request) that the request failed, so only logging it isn't really an option
08:12	jonathanj	i think if i create a channel for each request and put errors/results on it, that should work quite reliably
08:12	justin_smith	so then you need something to consume the result of that future - something that knows how to communicate with the client
08:13	jonathanj	the service effectively returns immediately with a URI to where the result will eventually be, the GET to that resource will block until the result is actually ready
08:15	jonathanj	anyway, there's definitely some stuff to play with, thanks, i'll try a few approaches and see what works best
08:21	jonathanj	justin_smith: oh something i forgot to mention is that i'm using PipedInputStream and PipedOutputStream, writing to the stream from the future; if the pipe buffer fills up (not reading data fast enough) then writes start blocking, so deref-ing the future too early will cause the reading thread (the main thread) to block and then you enter a deadlock
08:23	jonathanj	this could probably be avoided by using ByteArrayOutputStream or similar but that means allocating all the memory for the output ahead of time
08:25	justin_smith	jonathanj: or you could just check realized? before dereffing
08:25	justin_smith	if it's not realized it's still running
08:29	jonathanj	then we're back to the question of if it's not realized, when do i try deref it?
08:29	justin_smith	you could poll it
08:29	justin_smith	you could have a try/catch/finally where the finally puts something in action
08:29	justin_smith	(inside the future that is)
08:31	Glenjamin	does deref with a timeout help?
08:32	justin_smith	true, that's another option
08:34	jonathanj	what do i do if it times out?
08:35	BRODUS	i'm stumped on this problem http://www.4clojure.com/problem/78, is there a way to tell if a value is a function other than calling 'clojure.test/function?'
08:35	sunset-shimmer	hello, I need some help
08:36	justin_smith	,(fn? #())
08:36	clojurebot	true
08:37	sunset-shimmer	I have a for loop and a complex structure that I need to update in each iteration step. How to return final and fully updated structure from the loop?
08:37	BRODUS	justin_smith: thanks, i couldn't find that one
08:37	justin_smith	sunset-shimmer: for is not a loop
08:38	justin_smith	sunset-shimmer: you can use reduce with the for comprehension as its input, or perhaps use loop
08:38	justin_smith	but for is not a loop and isn't designed to do what you want
08:38	sunset-shimmer	ah, I see!
08:40	sunset-shimmer	I'll try reduce, loops are boring
08:41	justin_smith	sunset-shimmer: I'll make a guess that using the result of the for comprehension as the collection arg to reduce, you should be able to build up the result you want
08:50	jonathanj	i swear i ask this every week, but how to turn [[1 2] [3 4]] into [[1 3] [2 4]]?
08:51	jonathanj	,(apply map vector [[1 2] [3 4]])
08:51	clojurebot	([1 3] [2 4])
08:51	jonathanj	is there a limit on how many parameters can be passed with apply?
08:52	jeaye	,(doc apply)
08:52	clojurebot	"([f args] [f x args] [f x y args] [f x y z args] [f a b c d ...]); Applies fn f to the argument list formed by prepending intervening arguments to args."
08:52	jonathanj	i meant like a hard limit
09:04	sunset-shimmer	> derrida has left IRC
09:04	sunset-shimmer	sorry, I am lold
09:23	jonathanj	is there somewhere i could read about some common sync idioms written with core.async?
09:24	jonathanj	synchronous idioms, that is
10:07	powered	this feels wrong: (merge-with merge {:a {:a 1}} {:a {:b 2}})
10:07	powered	is there a better way?
10:08	beaky	,(merge-with merge {:a {:a 1}} {:a {:b 2}})
10:08	clojurebot	{:a {:a 1, :b 2}}
10:08	beaky	,(merge {:a {:a 1}} {:a {:b 2}})
10:08	clojurebot	{:a {:b 2}}
10:08	beaky	,(flatten {:a {:a 1}} {:a {:b 2}})
10:08	clojurebot	#error {\n :cause "Wrong number of args (2) passed to: core/flatten"\n :via\n [{:type clojure.lang.ArityException\n :message "Wrong number of args (2) passed to: core/flatten"\n :at [clojure.lang.AFn throwArity "AFn.java" 429]}]\n :trace\n [[clojure.lang.AFn throwArity "AFn.java" 429]\n [clojure.lang.AFn invoke "AFn.java" 36]\n [sandbox$eval73 invokeStatic "NO_SOURCE_FILE" 0]\n [sandbox$eva...
10:09	beaky	,(apply into {:a {:a 1}} {:a {:b 2}})
10:09	clojurebot	#error {\n :cause "Don't know how to create ISeq from: clojure.lang.Keyword"\n :via\n [{:type java.lang.IllegalArgumentException\n :message "Don't know how to create ISeq from: clojure.lang.Keyword"\n :at [clojure.lang.RT seqFrom "RT.java" 535]}]\n :trace\n [[clojure.lang.RT seqFrom "RT.java" 535]\n [clojure.lang.RT seq "RT.java" 516]\n [clojure.lang.ATransientMap conj "ATransientMap.java" 4...
10:09	beaky	:(
10:09	beaky	,(merge-with assoc {:a {:a 1}} {:a {:b 2}})
10:09	clojurebot	#error {\n :cause "Wrong number of args (2) passed to: core/assoc--4130"\n :via\n [{:type clojure.lang.ArityException\n :message "Wrong number of args (2) passed to: core/assoc--4130"\n :at [clojure.lang.AFn throwArity "AFn.java" 429]}]\n :trace\n [[clojure.lang.AFn throwArity "AFn.java" 429]\n [clojure.lang.RestFn invoke "RestFn.java" 427]\n [clojure.core$merge_with$merge_entry__4637 invoke...
10:09	beaky	ok i guess merge-with merge is the way to go
10:10	powered	I'll keep on mergin
10:10	beaky	you are merging maps nested 1-level deep via merge, see :D
10:10	j-pb	you could do this, sec
10:11	beaky	,(map merge {:a {:a 1}} {:a {:b 2}})
10:11	clojurebot	([:a {:a 1} [:a {:b 2}]])
10:15	BRODUS	,(take 5 (iterate identity :a))
10:15	clojurebot	(:a :a :a :a :a)
10:15	BRODUS	is there a better way of generating identity arrays than that?
10:16	BRODUS	something less verbose?
10:16	powered	repeat?
10:16	luma	,(repeat 5 :a)
10:16	clojurebot	(:a :a :a :a :a)
10:16	BRODUS	ah, thanks
10:16	beaky	,(repeat 10 ":D")
10:16	clojurebot	(":D" ":D" ":D" ":D" ":D" ...)
10:17	BRODUS	this language has too many useful functions to remember
10:17	luma	that's why we have http://clojure.org/cheatsheet
10:21	schmir	and http://conj.io
10:21	beaky	i love conj; reminds me of conjuncivitis
10:24	sunset-shimmer	test
10:26	yenda	is it possible to have both a repl and a cljs-repl running with a boot task and connect to them ?
10:26	yenda	or it doesn't even make sense ?
10:26	sunset-shimmer	justin_smith: great, I've wrote what I want with "reduce", thank you!
10:27	sunset-shimmer	it is my first usage of "reduce"!
10:47	yenda	I read that boot allows you to add dependencies without restarting the repl how to you do so ?
11:01	marchelzo	hi
11:03	marchelzo	how do most people install clojure? just unzip it and make an alias for 'java -cp /path/to/clojure-1.7.0.jar clojure.main'?
11:03	marchelzo	also is that what most people use for a repl, or is there a better one with readline bindings?
11:04	MJB47	most people use leiningen for both
11:04	MJB47	http://leiningen.org/
11:05	marchelzo	oh, cool
11:05	marchelzo	thanks
11:06	ARM9	in addition to leiningen I like setting up a clojure alias/script to the jar because lein repl takes an infuriating amount of time to start when you just want to try something quick
11:07	marchelzo	yeah I see that
11:32	justin_smith	ARM9: a similar trick is to make an uberjar, with clojure.core, plus pomegranate for adding maven (eg. clojars) deps at runtime, plus your favorite go-to libs outside core
11:44	marchelzo	how do you load a source file in the repl?
11:44	marchelzo	the lein repl
11:45	justin_smith	marchelzo: require, use, load, or load-file
11:45	justin_smith	same as in any other repl
11:45	marchelzo	I'm new to clojure in general so the fact that it's the same as any other repl doesn't make a difference :)
11:46	ARM9	(load-file "myfile.clj")
11:46	justin_smith	OK, with clojure.repl/doc you can see the docs for any of those functions
11:46	marchelzo	ok thanks!
11:47	justin_smith	marchelzo: see also clojure.repl/apropos and clojure.repl/find-doc which will search function names or docs, based on substrings or regex
11:48	marchelzo	awesome
11:49	justin_smith	also http://conj.io is a good overview of the core language with examples
11:49	marchelzo	so string literals are java.lang.Strings, but they are implicitly coerced to lists sometimes?
11:49	marchelzo	how can I make a list of chars be displayed as a string?
11:49	marchelzo	justin_smith: thanks, I think I need something like that
11:49	justin_smith	marchelzo: many sequence functions call seq on their arg
11:49	justin_smith	,(seq "hello")
11:49	ARM9	they are never implicitly coerced to lists, but sometimes sequences
11:50	clojurebot	(\h \e \l \l \o)
11:50	justin_smith	,(list? (seq "hello"))
11:50	clojurebot	false
11:50	marchelzo	,(take 3 "hello")
11:50	clojurebot	(\h \e \l)
11:50	marchelzo	what if I want that displayed as "hel"?
11:50	justin_smith	,(source take)
11:50	clojurebot	Source not found\n
11:50	justin_smith	,(apply str (take 3 "hello"))
11:50	clojurebot	"hel"
11:50	justin_smith	(subs "hello" 0 3) ; more efficient
11:51	justin_smith	,(subs "hello" 0 3)
11:51	clojurebot	"hel"
11:51	marchelzo	why apply str instead of just str?
11:51	justin_smith	,(str (take 3 "hello"))
11:51	marchelzo	oh
11:51	clojurebot	"clojure.lang.LazySeq@2076e"
11:51	marchelzo	,(str \h \e \l)
11:51	clojurebot	"hel"
11:51	marchelzo	I see
11:51	justin_smith	take 3 returns a lazy seq
11:52	justin_smith	and those print weird
11:52	justin_smith	err, those convert to string weirdly
11:53	justin_smith	marchelzo: unlike some functional languages (eg. haskell) a sequence of character and a string are not the same
11:53	justin_smith	and even in haskell they end up needing to make that distinction if they care about performance, eventually
11:54	marchelzo	right
11:54	marchelzo	I've never seen people complaining about clojure's strings so I assumed they didn't use list of char.
11:55	justin_smith	you can use class to find out the real jvm level class behind any piece of data
11:55	justin_smith	,(class "hello")
11:55	clojurebot	java.lang.String
11:55	justin_smith	,(class (seq "hello"))
11:55	clojurebot	clojure.lang.StringSeq
11:55	marchelzo	what would be the most idomatic way to apply a function 40 times to an argument?
11:56	TimMc	Do you want the results?
11:56	justin_smith	marchelzo: as in nested?
11:56	marchelzo	yes
11:56	marchelzo	to both
11:56	ARM9	what kind of function? what does it take? what does it return?
11:56	justin_smith	either (take 40 (iterate f arg)) or (nth (iterate f arg) 40)
11:56	marchelzo	its a -> a
11:56	justin_smith	depending if you want all the intermediates or not
11:57	justin_smith	,(nth (iterate #(* % Math/E) 1) 40)
11:57	clojurebot	2.35385266837019584E17
11:57	marchelzo	no just the final value; so (iterate f arg) is a lazy infinite sequence?
11:57	justin_smith	,(take 40 (iterate #(* % Math/E) 1))
11:57	clojurebot	(1 2.718281828459045 7.3890560989306495 20.085536923187664 54.59815003314423 ...)
11:57	justin_smith	marchelzo: indeed
11:58	marchelzo	ok, thank you.
11:58	ARM9	note that you'll run into trouble if you try to use side effects
11:58	justin_smith	marchelzo: sounds like you have enough haskell background that you'll pick up clojure quickly (if you get used to the non-purity thing)
11:59	justin_smith	yeah, laziness and side effects don't mix very nicely, and clojure doesn't enforce keeping them separate
11:59	marchelzo	yeah I've heard that
12:00	marchelzo	I'm sure I'll run into it soon enough
12:00	justin_smith	for example:
12:00	justin_smith	,(take 1 (map println (range)))
12:00	clojurebot	(0\nnil)
12:00	justin_smith	oh wait...
12:01	justin_smith	well, with the old version of range that used to be an issue :)
12:01	justin_smith	,(take 1 (map println [:a :b :c :d :e :f]))
12:01	clojurebot	(:a\n:b\n:c\n:d\n:e\n:f\nnil)
12:01	justin_smith	aha! the gotcha is still there in another form
12:02	justin_smith	(chunking is what makes this happen)
12:04	Bronsa	,(take 1 (map println (range 50)))
12:04	clojurebot	(0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n11\n12\n13\n14\n15\n16\n17\n18\n19\n20\n21\n22\n23\n24\n25\n26\n27\n28\n29\n30\n31\nnil)
12:04	Bronsa	justin_smith: (range) uses a different impl than (range n)
12:05	justin_smith	so I see
12:05	Bronsa	only the latter is chunked
12:05	justin_smith	Bronsa: were they both chunked at one time?
12:05	Bronsa	yes
12:05	Bronsa	pre 1.7
12:08	momerath	Is anyone using timbre and refactor-nrepl in the same file? When trying to do an extract-function (which was working a dozen dependency-changes ago), I get "<my-ns> is in a bad state! Error: No such namespace: timbre" (no relevant search results)
12:09	justin_smith	momerath: are you explicitly requiring timbre in every namespace where you use it?
12:09	momerath	what's the alternative? I'm requiring it and using the refer-timbre macro
12:10	justin_smith	momerath: some people use a namespace fully qualified, because it is required in some other ns. Which is a bad habit, though it works.
12:11	justin_smith	momerath: I'm guessing refer-timbre and refactor-nrepl don't play nicely. One doesnt' need refer-timbre, you can use regular require with :refer instead.
12:11	momerath	hrm- yeah, I guess I'll try that; thanks!
12:15	Bronsa	justin_smith: I might be wrong but it should be the case that the chunked pre 1.7 (range) would just reach Long/MAX_VALUE while the current non chunked version can promote to BigInt
12:16	momerath	now I just get the "bad state! Error:" with nothing after it
12:17	justin_smith	,(nth (range) (inc' Long/MAX_VALUE))
12:17	clojurebot	#error {\n :cause "Value out of range for long: 9223372036854775808"\n :via\n [{:type java.lang.IllegalArgumentException\n :message "Value out of range for long: 9223372036854775808"\n :at [clojure.lang.RT longCast "RT.java" 1217]}]\n :trace\n [[clojure.lang.RT longCast "RT.java" 1217]\n [clojure.lang.RT intCast "RT.java" 1167]\n [sandbox$eval25 invokeStatic "NO_SOURCE_FILE" 0]\n [sandbox$e...
12:17	justin_smith	I think the problem here is with nth though
12:17	Bronsa	I think so
12:17	Bronsa	(range) is defined as (iterate inc' 0)
12:18	Bronsa	,(take 10 (nthrest (range) Long/MAX_VALUE))
12:18	clojurebot	eval service is offline
12:18	Bronsa	:(
12:18	Bronsa	sorry clojurebot
12:18	justin_smith	Bronsa: just tried in my repl, we'll see if it returns this year or not
12:19	Bronsa	lol
12:21	Bronsa	uhm, LongRange could actually be O(1) rather than O(n) on nth
12:21	aurelian	what was the name of that thing that converted _ from json to - in clojurescript? as in: server returns json {"starred_at": "2015-12-09T10:06:23Z"} I want to have it in cljs as :started-at
12:23	justin_smith	aurelian: usually json converters take an optional keywordize option, but there's also valid reason to avoid keywordizing (eg. it's much better to have "foo bar" as a key in your map, as compared to (keyword "foo bar"))
12:23	justin_smith	,(keyword "foo bar") ; terrible
12:23	clojurebot	:foo bar
12:24	aurelian	hm, I have :keywordize to true
12:24	aurelian	using cljs-ajax to do the api call
12:24	justin_smith	but it's not doing the _ / - conversion
12:24	aurelian	nope
12:25	aurelian	I can access it as :starred_at but I think :started-at is nicer :)
12:25	aurelian	not that it will make a difference, but how I would do this kind of stuff?
12:27	justin_smith	,(keyword (clojure.string/replace (name :foo_bar) \_ \-))
12:27	clojurebot	:foo-bar
12:27	Bronsa	aurelian: https://github.com/qerub/camel-snake-kebab
12:27	justin_smith	oh yeah, that's a much better way
12:28	aurelian	cheers guys!
12:28	aurelian	or gals
12:28	aurelian	or both.
12:39	gfredericks	so it looks like if you accidentally with-redefs a macro you end up permanently unmacrofying it
12:51	yenda	Anybody here is using the system library ?
12:51	yenda	danielsz/system
12:54	yenda	I'm trying to figure out how I can pass one of my system component to a function I call in my ring app
12:54	yenda	in this case it is the db so that i can use the connection in the function
12:56	mavbozo	gfredericks, in my imagination, macro ~ expansion , unmacro ~ contraction, so all macro-expanded code gets contracted
13:00	justin_smith	gf~.
13:01	justin_smith	gfredericks: oops - you should be able to put the :macro metadata back on it, no?
13:01	justin_smith	as long as you didn't mess with the first two magic args
13:01	marchelzo	if i use 'lein deps' to download a dependency, is there a way to load it in the repl?
13:02	justin_smith	marchelzo: lein deps just puts the thing in your local package cache, in order to do the normal require you also need to add it to the classpath
13:02	MJB47	(use '[clojure.data.json :as json])
13:02	MJB47	obviously use whichever library you are actually using
13:03	justin_smith	there are libs like pomegranate and pallet/alembic that are designed to do both the download and the adding to classpath at runtime
13:03	justin_smith	MJB47: that only works if the dep is on your classpath already
13:03	MJB47	does lein deps not add to classpath?
13:03	justin_smith	MJB47: all lein deps does is download all deps to local cache that are implied by project.clj
13:04	MJB47	update project.clj -> lein deps -> lein repl has always worked properly for me
13:04	justin_smith	MJB47: so if you already had a repl running, that dep is not added to the running repl
13:04	MJB47	oh ye
13:04	MJB47	need a new repl
13:04	justin_smith	right
13:05	justin_smith	so I might be reading too much into the question - I thought "adding the dep to a running repl" was implied
13:05	MJB47	i assumed the opposite
13:05	MJB47	oh well
13:06	gfredericks	justin_smith: yeah, I think you could fix it fine by calling .setMacro afterwards
13:06	gfredericks	but it's super confusing
13:06	gfredericks	I made http://dev.clojure.org/jira/browse/CLJ-1867
13:06	justin_smith	yeah, that is an odd behavior
13:06	gfredericks	(which includes the root cause)
13:11	casey1	quite
13:34	wolgo	'/help
15:58	lxsameer	hey folks, I'm looking for a free PaaS for my clojure aoo
15:58	lxsameer	*app
15:58	MJB47	try heroku
16:00	lxsameer	MJB47: heroku has limitations
16:01	MJB47	i doubt you will find a free one without
16:01	lxsameer	MJB47: openshift limiation is kind of nice, but It does not support clojure by default
16:02	celwell	elastic beanstalk micro instance should be free for a year i think
17:07	mjg	Hi! Can I use 'binding' to bind a dynamic var in another ns when the name of the ns is passed to me as a string?
17:08	justin_smith	only if you use eval I think
17:09	mjg	like (binding [ns (create-ns 'other-ns) other-ns/foo "hello"] (eval (read-string "foo"))) ?
17:09	justin_smith	umm... what are you trying to do here?
17:11	mjg	I'm writing a small lazybot-esque thing.
17:12	mjg	So, each time my fn is called, there's a string which is the form to evaluate, a string which is the chatroom-name and a string which is the name of the user who spoke to the bot.
17:13	mjg	I'd like to eval the form in a ns which is named after the chatroom, with that-chatroom/me bound to the user's name.
17:15	mjg	justin_smith: so far https://gist.github.com/mjg123/a1dca856cd08682f5676 works, but with only one ns.
17:21	justin_smith	mjg: what about using in-ns inside the eval'd code?
17:22	justin_smith	eg (eval (concat '(in-ns user-specific-ns) user-code))
17:22	justin_smith	or maybe that's missing some parens
17:23	mjg	Where can I re-bind the me var in user-specific-ns in that case?
17:23	justin_smith	mjg: you can use intern to set the binding
17:24	mjg	justin_smith: can you use intern like that?!
17:24	justin_smith	,(intern 'foo.bar 'baz "hello")
17:24	clojurebot	#error {\n :cause "No namespace: foo.bar found"\n :via\n [{:type java.lang.Exception\n :message "No namespace: foo.bar found"\n :at [clojure.core$the_ns invokeStatic "core.clj" 4011]}]\n :trace\n [[clojure.core$the_ns invokeStatic "core.clj" 4011]\n [clojure.core$intern invokeStatic "core.clj" 6047]\n [clojure.core$intern invoke "core.clj" -1]\n [sandbox$eval25 invokeStatic "NO_SOURCE_FILE"...
17:25	justin_smith	mjg: oops - ns has to exist first
17:25	justin_smith	,(in-ns 'foo.bar)
17:25	clojurebot	#object[clojure.lang.Namespace 0x6c822bda "foo.bar"]
17:25	justin_smith	,(intern 'foo.bar 'baz "hello")
17:25	clojurebot	#'foo.bar/baz
17:25	justin_smith	,[ns foo.bar/baz]
17:25	clojurebot	[#object[clojure.lang.Namespace 0x1227d02b "sandbox"] "hello"]
17:26	justin_smith	so we are still in sandbox (one clojurebot query does not use the ns another creates) but I was able to create foo.bar/baz from sandbox
17:27	mjg	but that's not a dynamic binding is it? All threads will see the interned value.
17:27	justin_smith	mjg: the var belongs to a specific ns
17:29	mjg	I think I need to use 'binding' to avoid different users seeing each other's names (each incoming request is handled by a separate thread_
17:30	justin_smith	they can't have their own namespaces?
17:30	mjg	users? no
17:30	mjg	I want one ns per room.
17:31	justin_smith	mjg: you can create the dynamic var with no root binding, then bind it explicitly
17:32	mjg	justin_smith: inside the 'eval ?
17:32	justin_smith	I think so, yeah
17:32	mjg	OK let me experiment with that. Thanks for your help.
17:32	justin_smith	because eval doesn't use your local environment really
17:32	sdegutis	Is there a nicer way to do (->> (for [x] (if? (f x) (g x))) (remove nil?))
17:33	sdegutis	Notice how technically my question still ends in a question mark.
17:33	justin_smith	(keep #(when (f %) (g %)) coll)
17:34	justin_smith	,(keep #(when (even? %) (inc %)) (range))
17:34	clojurebot	(1 3 5 7 9 ...)
17:34	amalloy	what on earth is if?
17:35	amalloy	also what is (for [x] ...)
17:35	justin_smith	amalloy: I was going to ask what (for [x] was...
17:35	justin_smith	heh
17:47	justin_smith	,(defmacro if? [& body] `(boolean (if ~@body)))
17:47	clojurebot	#'sandbox/if?
17:47	justin_smith	,(if? true 42)
17:47	clojurebot	true
17:51	sdegutis	Thanks justin_smith
17:52	sdegutis	amalloy, justin_smith: It seems I am not fully with it right now.
18:05	rkpaul	I'm trying to reify a class where I have the classname in a string: (reify (resolve (symbol myclassname)) (apply [this, x] "a")) But I'm getting an error message: ClassCastException clojure.lang.PersistentList cannot be cast to clojure.lang.Symbol What am I doing wrong?
18:07	alive876	hi, newbie here, i get this error Could not find artifact secretary:secretary:jar:“1.2.3” , my project.clj is: http://pastebin.com/Vdmn3z9n thanks much!
18:07	amalloy	rkpaul: "trying to reify a class where I have the classname in a string" is the wrong part
18:07	rkpaul	amalloy: wrong part as in that's not causing the error?
18:08	amalloy	as in you can't do that
18:08	rkpaul	ah ok
18:08	amalloy	i mean, it's not impossible but
18:08	amalloy	it's not easy
18:08	rkpaul	so let's say that I have four different java classes and I want to pick which one to use there based on some predicate... would I be better off just doing a switch statement kind of thing?
18:09	amalloy	yes
18:09	rkpaul	ok thanks
18:11	WorldsEndless	Anyoen have recommendations on debugging a "Exception in thread "main" java.lang.ExceptionInInitializerError" when trying to run my uberjar?
18:13	mjg	justin_smith: So I can't get that to work :( the problem AIUI is that you can't put the 'binding' call inisde the 'eval' cos then you lose access to the outer scope.
18:15	mjg	justin_smith: I think I need to create the bindings then eval the code w/those bindings active. But I just can't see how to bind a var in an ns when IDK the name of the ns until runtime.
18:26	justin_smith	mjg: clearly the binding has to also be inside the eval
18:27	sdegutis	Will #(foo %) late-bind so that if I change the function that #'foo points to, my anonymous function will call the new one?
18:27	sdegutis	Thanks in advance. Regards.
18:33	justin_smith	sdegutis: yes, #(foo %) will see new values for foo - the way you get the "stuck" version is if you have ((fn [f] #(f %)) foo)
18:37	sdegutis	justin_smith: why is that?
18:37	justin_smith	sdegutis: ((fn [f] #(f %)) foo) - the function that generates that function never sees the var, just the value of the var
18:37	justin_smith	as opposed to #(foo %) - that actually sees the var
18:39	sdegutis	Oooooh.
18:39	sdegutis	Thank!
19:36	slester	Newb here, trying to (dissoc hashed-map '(list of keywords)) -- is there a way to make that possible? do I need to (apply #(dissoc hashed-map %1) '(list))?
19:37	slester	err, reduce I guess.
19:41	slester	got it, sorry, nvm!
20:02	amalloy	slester: i'd use apply
20:02	amalloy	(apply dissoc m kws)
20:04	slester	amalloy: thanks!
20:11	sdegutis	justin_smith: it still doesn't make sense to me though
20:11	sdegutis	((fn [f] #(f %)) foo)
20:11	sdegutis	Isn't writing "foo" just referencing a var?
20:11	sdegutis	justin_smith: So that the anonymous function receives a far?
20:11	sdegutis	*var
20:30	tolstoy	slester You could also use "select-keys" to keep the ones you want.
20:30	tolstoy	BTW, clojure.set.rename-keys -> super handy when you need it.
20:47	BRODUS	one thing im confused about: i read its idiomatic to use vectors in clojure over lists, im currently doing that but im having issues because map, filter, etc.. return lazy sequences which behave like lists, so how do I use map, filter, etc.. without having to use (into [] result) after each one?
20:49	sumobob	whats the clojure equivalent of pushing to an array?
20:49	tolstoy	BRODUS Try mapv and filterv?
20:49	BRODUS	,
20:49	clojurebot	#<RuntimeException java.lang.RuntimeException: EOF while reading>
20:50	tolstoy	,(map inc [1 2 3])
20:50	clojurebot	(2 3 4)
20:50	tolstoy	,(mapv inc [1 2 3])
20:50	clojurebot	[2 3 4]
20:51	BRODUS	ah ok, so that means that i lose the benefits of a lazy sequence then
20:53	tolstoy	Oh, mapv isn't lazy?
20:54	TEttinger	map is. mapv isn't.
20:54	tolstoy	BRODUS: I just use regular lists can convert to a vector only at the end, when I actually need it. (->> (map this seq) (filter that) (reduce whatever) vec).
20:54	sumobob	what is the difference between "a" and \a
20:55	sumobob	,(type "a")
20:55	clojurebot	java.lang.String
20:55	sumobob	,(type \a)
20:55	tolstoy	sumobob First is a string type, the second a char type.
20:55	clojurebot	java.lang.Character
20:55	BRODUS	,(seq? "a")
20:55	clojurebot	false
20:55	BRODUS	,(coll? "a")
20:55	clojurebot	false
20:56	sumobob	hmm, i'm trying to do a case statement based on a char, but its not being too friendly with me
20:58	TEttinger	sumobob: there may be a better fit than case
20:59	amalloy	BRODUS: it's certainly not "idiomatic to use vectors instead of lists" in general
20:59	sumobob	I'm working on some problems from a site called adventofcode.com
21:00	amalloy	it's just like when you are typing a list literal into code you'd usually use a vector. when you're building a data structure at runtime, pick the one that has the performance characteristics you want
21:00	sumobob	its basically a massive string like ">>><<v^" which needs to be used as directions, go left, go right etc etc
21:00	TEttinger	which day?
21:00	sumobob	day 3
21:01	sumobob	I'm doing it recursively
21:01	sumobob	i have a function that takes a string and an array
21:02	sumobob	based on the first char of the string, i conj a new object onto the array and call my function again with (rest string)
21:09	BRODUS	amalloy: i agree. I was trying to understand what rich said here: http://stackoverflow.com/questions/1147975/in-clojure-when-should-i-use-a-vector-over-a-list-and-the-other-way-around but i guess "idiomatic" was the wrong word
21:10	amalloy	well yes, you don't super often build lists. but you build seqs all the time
21:14	TEttinger	,(let [input ">>><<v^"] (count (distinct (reduce (fn [[latest & others :as houses] dir] (conj houses (condp = dir \< (update-in latest [0] dec) \> (update-in latest [0] inc) \^ (update-in latest [1] inc) \v (update-in latest [1] dec)))) '([0 0]) input))))
21:14	clojurebot	5
21:14	TEttinger	fun
21:40	devn	so, it's been awhile since i looked at this
21:41	devn	but im puzzling a little bit. i don't recall why (+) is the right thing here:
21:41	TEttinger	hey devn
21:41	devn	,(#(`[[~@%&]] (+)) "A")
21:41	clojurebot	["A"]
21:41	TEttinger	,(+)
21:41	clojurebot	0
21:41	devn	wait, don't finish that thought -- staring at it
21:42	TEttinger	oh I know
21:42	TEttinger	,(#(`[~@%&]) "A")
21:42	clojurebot	#error {\n :cause "Wrong number of args (0) passed to: PersistentVector"\n :via\n [{:type clojure.lang.ArityException\n :message "Wrong number of args (0) passed to: PersistentVector"\n :at [clojure.lang.AFn throwArity "AFn.java" 429]}]\n :trace\n [[clojure.lang.AFn throwArity "AFn.java" 429]\n [clojure.lang.AFn invoke "AFn.java" 28]\n [sandbox$eval77$fn__78 doInvoke "NO_SOURCE_FILE" 0]\n [...
21:43	TEttinger	see, otherwise it would try to call the vector instead of returning the 0th element of a nesting vector
21:43	TEttinger	,((fn [& args] [args] 0) "A")
21:43	clojurebot	0
21:44	TEttinger	,((fn [& args] ([args] 0)) "A")
21:44	clojurebot	("A")
21:44	TEttinger	a little more clear why it does what it does, devn?
21:44	devn	haha, im feeling a little slow right now
21:44	devn	im trying to walk it through in my head
21:45	justin_smith	,(/ (+))
21:45	clojurebot	#error {\n :cause "Divide by zero"\n :via\n [{:type java.lang.ArithmeticException\n :message "Divide by zero"\n :at [clojure.lang.Numbers divide "Numbers.java" 158]}]\n :trace\n [[clojure.lang.Numbers divide "Numbers.java" 158]\n [clojure.lang.Numbers divide "Numbers.java" 3784]\n [clojure.core$_SLASH_ invokeStatic "core.clj" 994]\n [clojure.core$_SLASH_ invoke "core.clj" -1]\n [sandbox$ev...
21:45	TEttinger	,(#([%&] (+)) "A")
21:45	clojurebot	("A")
21:45	devn	nono, i get the identity thing for (+)
21:45	justin_smith	devn: I just thought (/ (+)) was a funny way to get a divide by 0
21:45	devn	:D
21:46	devn	,(/(*)(+))
21:46	clojurebot	#error {\n :cause "Divide by zero"\n :via\n [{:type java.lang.ArithmeticException\n :message "Divide by zero"\n :at [clojure.lang.Numbers divide "Numbers.java" 158]}]\n :trace\n [[clojure.lang.Numbers divide "Numbers.java" 158]\n [sandbox$eval206 invokeStatic "NO_SOURCE_FILE" 0]\n [sandbox$eval206 invoke "NO_SOURCE_FILE" -1]\n [clojure.lang.Compiler eval "Compiler.java" 6943]\n [clojure.la...
21:46	justin_smith	,(/ (*))
21:46	TEttinger	it's because you can't use alphanumerics in swearjure, and 0 is numeric
21:46	clojurebot	1
21:46	devn	googly eyes
21:46	TEttinger	it's getting the 0th element of the vector
21:46	TEttinger	that contains a vector of all args passed to it
21:46	devn	why does it need the nesting?
21:46	TEttinger	(where it is the anon fn)
21:47	justin_smith	devn: it needs to become a vector
21:47	TEttinger	,(#(`[~@%&] 0) "A")
21:47	clojurebot	"A"
21:47	devn	well the unquote splicing
21:47	devn	ahh right
21:47	devn	ok ok
21:47	TEttinger	,(#(`[~@%&] 0) "A" "B")
21:47	clojurebot	"A"
21:47	TEttinger	,(#(`[[~@%&]] 0) "A" "B")
21:47	clojurebot	["A" "B"]
21:47	devn	yes, that's what i needed, makes good sense now
21:47	TEttinger	cool
21:47	TEttinger	swearjure is nice and mindbending
21:48	devn	here's the other one from the same post, weirder still
21:48	justin_smith	~(#(`[~@%&] 0) "A") makes good sense
21:48	clojurebot	Excuse me?
21:48	justin_smith	haha
21:48	devn	,(#(`[{~% ~@%&}] (+)) :a 1)
21:48	clojurebot	{:a 1}
21:49	devn	"The Clojure reader enforces all hash maps to contain an even element of arguments—even if the element is going to be unquote spliced. I'm not sure if this is a bug in Clojure or me pushing the limits of what the Clojure reader is supposed to support, though I wouldn't be surprised if it is the latter."
21:49	devn	so, were it not for that limitation, it would be the same as vector, but with no ~% in the key position
21:50	devn	(i think)
21:50	devn	hyPiRion: waves
21:51	devn	i kinda like the symmetry of:
21:51	devn	,(#(`[{~@%& ~@%&}] (+)) :a 1)
21:51	clojurebot	{:a 1}
21:51	justin_smith	,{#_ foo :a 0}
21:52	clojurebot	{:a 0}
21:52	devn	one fun bit about that is, even though you can't rely on the ordering of maps:
21:52	devn	,(#(`[{~@%& ~@%&}] (+)) :a 1 :b 2 :c 3)
21:52	clojurebot	{:c 3, :b 2, :a 1}
21:52	devn	,{:a 1 :b 2 :c 3}
21:52	clojurebot	{:a 1, :b 2, :c 3}
21:52	devn	btw: hi TEttinger :)
21:52	devn	aloha justin_smith
21:53	TEttinger	hallo!
21:53	justin_smith	zdrasvitye
21:53	devn	something clojure this way comes
21:55	sumobob	wtf
21:56	devn	what y'all hackin' on these days?
21:56	sumobob	,(- 1 0)
21:56	clojurebot	1
21:56	sumobob	,(- 0 1)
21:56	clojurebot	-1
21:56	sumobob	whaaat
21:56	justin_smith	,(- 3 2 1)
21:56	clojurebot	0
21:56	sumobob	can someone explain this for me?
21:56	justin_smith	sumobob: 0 - 1 is -1
21:56	devn	1 - 0 = 1
21:56	devn	0 - 1 = -1
21:57	devn	sumobob: what'd you expect?
21:57	devn	,(< 1 0)
21:57	clojurebot	false
21:57	devn	,(> 1 0)
21:57	clojurebot	true
21:57	sumobob	for some reason i just thought it would subtract everything haha
21:58	sumobob	but yeah operational order matters lol
21:58	devn	the lt and gt operators will never get easier for me
21:58	justin_smith	devn: the height moves in the direction of the size of the numbers
21:58	justin_smith	> lower to the right, just like the numbers
21:58	justin_smith	,(> 5 4 3 2 1 0 -1)
21:58	clojurebot	true
21:59	justin_smith	< higher to the right, just like the numbers
21:59	devn	yeah yeah i know, but man, to think of "the larger number eats the smaller number" from 1st grade in order to remember that kills me
21:59	justin_smith	,(< 0 1 2 3)
21:59	clojurebot	true
21:59	devn	i haven't golfed in awhile, have been missing it
21:59	justin_smith	devn: no eating - it's a graph of the numbers in the argument list
21:59	justin_smith	line graph
21:59	devn	justin_smith: ah, that's actually a better way of thinking about it
21:59	devn	thanks
22:00	justin_smith	np
22:00	devn	im pretty anti-golf these days
22:00	devn	i prefer explicit (fn [...] ...) over (partial ...)
22:00	justin_smith	devn: oh, I don't golf in real code
22:00	devn	(in shared code that is)
22:01	devn	it kills me when i see a partial, and it's not immediately obvious if it's going to take & args, arg1 arg2, etc.
22:02	devn	i also have pretty much stopped using #()
22:02	justin_smith	if only partial was curry - then you know it always takes exactly one more arg
22:02	devn	explicit fn all the time
22:02	devn	justin_smith: nod
22:02	devn	speaking of shared code, programming on a team, etc...
22:03	devn	is there any hope, do y'all think, that we'll ever get a set of standard map-processing functions in core?
22:03	devn	(map-keys) (map-vals) (filter-keys) (filter-vals) (filter-kvs) (map-kvs) etc.
22:05	jhn	all of that is just one reduce away
22:05	devn	that, and as long as im ranting and raving: when are transients gonna get some love? no update! update-in! etc.
22:06	devn	jhn: oh im aware, but when i see people write them, they often forget they can use a transient, or don't use reduce-kv
22:06	devn	it'd be so much nicer if they just lived in core
22:06	devn	no "here, i wrote this utility library that adds functions that ought to be in core"
22:06	jhn	yeah. the one i always see myself reimplementing is map-vals
22:07	amalloy	just use into
22:07	amalloy	i mean it'd be nice if map-vals existed, but if you implement it yourself use into instead of reduce
22:08	jhn	is this not idiomatic? https://github.com/jhn/tobias/blob/master/src/tobias/util.clj#L17-L18
22:08	devn	amalloy: why not reduce-kv with a transient persistent! around it?
22:08	amalloy	because into already does the transient part
22:09	devn	but it won't work recursively right?
22:09	devn	because the submaps aren't ieditable?
22:11	devn	,(let [x (transient {:a 1 :b 2 :c {:d 3}})] (type (:c x)))
22:11	clojurebot	clojure.lang.PersistentArrayMap
22:11	devn	:((((
22:12	devn	i think cgrande wrote something about this a long while back
22:12	devn	ah, im thinking of https://github.com/cgrand/megaref
22:13	devn	perhaps specter is closer to what im after in that case
22:19	mgaare	Yeah, transients aren't recursive like that. Ran into that problem too
22:20	devn	I sat down and started writing a thing to handle the recursive case, but it got ugly quick
22:21	devn	cant remember the exact situation i was in -- pretty sure i was making something that'd give the person using the function the /choice/ of whether they wanted to pass a transient or not
22:21	devn	which meant switching out assoc! for assoc, etc.
22:39	domgetter	Do for loops not work inside go blocks?
22:40	amalloy	~for
22:40	clojurebot	for is like doseq, but for values instead of side effects
22:40	domgetter	(go (for [x (range 1 10)] (>! c x))) doesn't seem to put anything on channel c
22:40	justin_smith	domgetter: for is lazy
22:40	justin_smith	use doseq there
22:40	devn	domgetter: what happens if you wrap (for ...) with (doall ...)
22:40	justin_smith	for is only for generating values
22:40	devn	but also yes, doseq.
22:41	devn	it's been awhile since i've used core.async
22:41	devn	what does (>! c x) return? a channel?
22:41	justin_smith	devn: nil
22:41	devn	ah
22:41	devn	go returns a chan though
22:41	devn	right?
22:41	clojurebot	right is not wrong
22:42	justin_smith	devn: right, it would either return a list of nils or if you switch for with doseq it would return a single nil
22:42	justin_smith	s/list/seq of course
22:42	domgetter	got it, thank you
22:43	justin_smith	domgetter: I think devn had a point there - if you had read from the channel returned by go, you would get a lazy-seq, and for each value you consumed you would likely make one of those >! calls happen - but doeseq is the right way to do what you are doing there
22:45	justin_smith	or wait, the !> would try to happen in the context where you read the value, which if it was not inside another go block would be a weird error
22:46	devn	ah, now im remembering more transient weirdness
22:46	domgetter	Yea I kept getting cannot convert ISeq to ManyToMany errors
22:46	devn	,(require '[clojure.walk :as walk])
22:46	clojurebot	nil
22:46	devn	,(walk/postwalk (fn [x] (if (map? x) (transient x) x)) {:a 1 :b {:c 3 :d {:e 4 :f {:g 6}}}})
22:46	clojurebot	#object[clojure.lang.PersistentArrayMap$TransientArrayMap 0x6c509ac3 "clojure.lang.PersistentArrayMap$TransientArrayMap@6c509ac3"]
22:46	devn	,(def transients-all-the-way-down (walk/postwalk (fn [x] (if (map? x) (transient x) x)) {:a 1 :b {:c 3 :d {:e 4 :f {:g 6}}}})b)
22:46	clojurebot	#error {\n :cause "Too many arguments to def"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.RuntimeException: Too many arguments to def, compiling:(NO_SOURCE_PATH:0:0)"\n :at [clojure.lang.Compiler analyzeSeq "Compiler.java" 6891]}\n {:type java.lang.RuntimeException\n :message "Too many arguments to def"\n :at [clojure.lang.Util runtimeException "Util.jav...
22:47	devn	,(def transients-all-the-way-down (walk/postwalk (fn [x] (if (map? x) (transient x) x)) {:a 1 :b {:c 3 :d {:e 4 :f {:g 6}}}}))
22:47	clojurebot	#'sandbox/transients-all-the-way-down
22:47	devn	,(defn transient? [x] (instance? clojure.lang.ITransientCollection x))
22:47	clojurebot	#'sandbox/transient?
22:49	justin_smith	devn: I wonder how the time spent checking for transient status or not compares to the time saved by using transients
22:49	devn	,(walk/postwalk (fn [x] (if (transient? x) (persistent! x) x)) transients-all-the-way-down)
22:49	clojurebot	{:a 1, :b #object[clojure.lang.PersistentArrayMap$TransientArrayMap 0x247c1594 "clojure.lang.PersistentArrayMap$TransientArrayMap@247c1594"]}
22:51	devn	not sure why that's the case -- postwalk should hit {:g 6}, {:e 4 :f {:g 6}}, {:c 3 :f {e 4 :f {:g 6}}, and then the top level
22:51	justin_smith	sure, but it didn't print readable
22:51	devn	i would have expected the whole thing to be persistent at that point
22:52	justin_smith	or are you saying the top level one should be transient too?
22:52	justin_smith	right
22:52	devn	either that's a bug, or im doing it wrong
22:52	justin_smith	,(walk/postwalk (fn [x] (if (transient? x) (persistent! x) x)) [transients-all-the-way-down])
22:52	clojurebot	#error {\n :cause "Transient used after persistent! call"\n :via\n [{:type java.lang.IllegalAccessError\n :message "Transient used after persistent! call"\n :at [clojure.lang.PersistentArrayMap$TransientArrayMap ensureEditable "PersistentArrayMap.java" 457]}]\n :trace\n [[clojure.lang.PersistentArrayMap$TransientArrayMap ensureEditable "PersistentArrayMap.java" 457]\n [clojure.lang.ATransient...
22:53	justin_smith	oh, right, that was a side effect
22:54	devn	well, i got further :)
22:54	devn	,(let [transients (walk/postwalk (fn [x] (if (map? x) (transient x) x)) {:a 1 :b {:c 3 :d {:e 4 :f {:g 6}}}})] (walk/postwalk (fn [x] (if (transient? x) (persistent! x) x)) (persistent! transients)))
22:54	clojurebot	{:a 1, :b {:c 3, :d #object[clojure.lang.PersistentArrayMap$TransientArrayMap 0x5a88a5eb "clojure.lang.PersistentArrayMap$TransientArrayMap@5a88a5eb"]}}
22:58	justin_smith	devn: I don't think postwalk can do it properly because it doesn't know how to walk down into the transients, but a pre-walk could do it
22:59	devn	oh duh, right
22:59	devn	weird, wonder how i missed that...
23:00	devn	i could swear i tried a prewalk
23:00	devn	,(let [transients (walk/postwalk (fn [x] (if (map? x) (transient x) x)) {:a 1 :b {:c 3 :d {:e 4 :f {:g 6}}}})] (walk/prewalk (fn [x] (if (transient? x) (persistent! x) x)) transients))
23:00	clojurebot	#error {\n :cause "No such namespace: walk"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.RuntimeException: No such namespace: walk, compiling:(NO_SOURCE_PATH:0:0)"\n :at [clojure.lang.Compiler analyze "Compiler.java" 6704]}\n {:type java.lang.RuntimeException\n :message "No such namespace: walk"\n :at [clojure.lang.Util runtimeException "Util.java" 221]}]...
23:00	devn	,(require '[clojure.walk :as walk])
23:00	clojurebot	nil
23:00	devn	,(defn transient? [x] (instance? clojure.lang.ITransientCollection x))
23:00	clojurebot	#'sandbox/transient?
23:00	devn	,(let [transients (walk/postwalk (fn [x] (if (map? x) (transient x) x)) {:a 1 :b {:c 3 :d {:e 4 :f {:g 6}}}})] (walk/prewalk (fn [x] (if (transient? x) (persistent! x) x)) transients))
23:00	clojurebot	{:a 1, :b {:c 3, :d {:e 4, :f {:g 6}}}}
23:01	devn	huzzah
23:05	devn	justin_smith: I have the same question as you about performance
23:05	devn	that check isn't free
23:05	devn	quite the opposite
23:09	devn	,(dotimes [_ 1000] (time (let [transients (-> {:a 1 :b {:c 3 :d {:e 4 :f {:g 6}}}} (update-in [:b :d :f] transient) (update-in [:b :d] transient) (update-in [:b] transient) transient)] (-> transients persistent! (update-in [:b] persistent!) (update-in [:b :d] persistent!) (update-in [:b :d :f] persistent!)))))
23:09	clojurebot	"Elapsed time: 0.323082 msecs"\n"Elapsed time: 0.173159 msecs"\n"Elapsed time: 0.174552 msecs"\n"Elapsed time: 0.166604 msecs"\n"Elapsed time: 0.162875 msecs"\n"Elapsed time: 0.162494 msecs"\n"Elapsed time: 0.162726 msecs"\n"Elapsed time: 0.153142 msecs"\n"Elapsed time: 0.156263 msecs"\n"Elapsed time: 1.078818 msecs"\n"Elapsed time: 0.164292 msecs"\n"Elapsed time: 0.16227 msecs"\n"Elapsed time: 0....
23:10	devn	,(dotimes [_ 1000] (time (let [transients (walk/postwalk (fn [x] (if (map? x) (transient x) x)) {:a 1 :b {:c 3 :d {:e 4 :f {:g 6}}}})] (walk/prewalk (fn [x] (if (transient? x) (persistent! x) x)) transients))))
23:10	clojurebot	"Elapsed time: 0.986332 msecs"\n"Elapsed time: 0.461197 msecs"\n"Elapsed time: 86.447148 msecs"\n"Elapsed time: 0.458364 msecs"\n"Elapsed time: 0.456384 msecs"\n"Elapsed time: 0.456643 msecs"\n"Elapsed time: 0.473551 msecs"\n"Elapsed time: 0.457109 msecs"\n"Elapsed time: 0.457108 msecs"\n"Elapsed time: 0.482885 msecs"\n"Elapsed time: 0.549637 msecs"\n"Elapsed time: 0.459312 msecs"\n"Elapsed time: ...
23:10	devn	A very poor man's benchmark, but I'm seeing ~0.03msecs for the post/pre
23:11	devn	0.01msecs for the straight ahead update-in
23:11	devn	so, specter... :D
23:16	devn	https://gist.github.com/devn/b195dbc67a320021057c here if someone is interested in tinkering with it, would be interested to see other approaches
23:37	domgetter	Is there a way to ask the result of make-array for its size?
23:37	domgetter	(assert (= 3 (size (make-array Long/TYPE 3))))
23:38	domgetter	what goes here? ^
23:39	domgetter	got it. It's alength
23:39	justin_smith	domgetter: count
23:40	domgetter	count also works. are they synonymous?
23:40	justin_smith	,(count (make-array Long/TYPE 3))
23:40	clojurebot	3
23:40	justin_smith	domgetter: count is more general
23:40	domgetter	ah okay. Thank you
23:40	justin_smith	,(count "hello, world!")
23:40	clojurebot	13
23:40	justin_smith	,(alength "hello, world!")
23:40	clojurebot	#error {\n :cause "No matching method found: alength"\n :via\n [{:type java.lang.IllegalArgumentException\n :message "No matching method found: alength"\n :at [clojure.lang.Reflector invokeMatchingMethod "Reflector.java" 80]}]\n :trace\n [[clojure.lang.Reflector invokeMatchingMethod "Reflector.java" 80]\n [clojure.lang.Reflector invokeStaticMethod "Reflector.java" 207]\n [sandbox$eval73 invo...
23:53	lambda-11235	How do clojurebot's error messages work? Is there a library to do that?
23:54	justin_smith	the message is exactly how exception objects are printed since 1.7
23:56	justin_smith	it was better back when it was just the message - because with a bot we really don't want or need the stack trace