#clojure – 2015-03-21

2015-03-21

00:45	arav93	Goodnight! :)
02:48	aytch	#16 is a bit tricky
02:49	aytch	(= (__ "Dave") "Hello, Dave!")
02:49	aytch	the naive response (mine) was: str "Hello, "
02:50	aytch	but that doesn't evaluate as true, because it needs the "!" at the end
02:52	aytch	(= (str "Hello, " "Dave") "Hello, Dave")
02:52	aytch	true
02:52	aytch	(= (str "Hello, " "Dave") "Hello, Dave!")
02:52	aytch	false
02:52	TEttinger	yep
02:52	TEttinger	so you need to define a function there
02:53	aytch	yeah, I'm realizing that
02:53	aytch	it's just an exponential leap in difficulty
02:53	aytch	strings were only introduced in a question or two before
02:53	Seylerius	What's this: koans or something?
02:53	Seylerius	Or 4clojure?
02:53	aytch	Seylerius: 4clojure
02:54	TEttinger	(fn [name] (str "beginning " name " end"))
02:54	aytch	the title of the problem is "Hello World"
02:54	aytch	not "String Concatenation"
02:54	TEttinger	heh, hello world usually involves string concatenation as the second step
02:54	TEttinger	hello yourname
02:55	aytch	Absolutely, I agree
02:55	TEttinger	4clojure definitely gets challenging quickly
02:55	TEttinger	have you reimplemented nth yet?
02:55	Seylerius	Annoyingly, 4clojure doesn't let me sign up.
02:56	aytch	I'm guessing no
02:56	TEttinger	that's one of the tasks that comes up around 20-30-something I think
02:56	TEttinger	it's a good challenge
02:57	amalloy	Seylerius: doesn't let you sign up?
02:58	Seylerius	Well, it let me sign up, but it keeps giving me an error on log in, and not a password error.
02:58	Seylerius	Okay, the problem seems to have been related to my username being capitalized.
03:26	aytch	I don't know who _pcl is, but all their answers match up with mine. And other people do some weird voodoo.
04:13	Seylerius	Random but funny bit of dialogue from something I read recently: "Great. That probably means I'll be shooting eyebeams by next week." ;; "That was actually a party trick of your great-grandfather's, if I remember the stories correctly. He used it to incinerate enemies, destroy citadels and open canned goods, for which I am sure that your great grandmother was ever grateful."
04:13	Seylerius	Totally off topic, but amusing.
04:42	Seylerius	Y'know what's weird? Sometimes the 4clojure tests display one of the tests as failed, even though the solution is correct and the problem gets marked as solved.
04:42	Seylerius	Only seems to happen on the multi-test problems.
04:50	aytch	Seylerius: on the multi-test problems, there is only one correct solution.
04:51	aytch	the code will either pass all of the tests, or none of them, but the graphics are misleading.
04:51	Seylerius	aytch: Exactly. And I submit the right one, the system marks that I've passed, but one of the tests gets a nice red dot, even though all logic says it should have passed that test too.
04:52	Seylerius	It's very odd.
04:52	aytch	errr....there are multiple correct ways to implement the solution, but one solution must pass all tests.
04:52	aytch	I was asking about this a few days ago.
04:52	Seylerius	There must be some kind of bug in the rendering.
04:53	Seylerius	It can't really be failing that test, because I wouldn't get a "Solved!" result, but it still looks like it failed that test.
04:53	Seylerius	Very strange.
04:53	aytch	Which #?
04:53	Seylerius	I can't remember which one did it last. Maybe 17 or 18? I'll pipe up next time it does it.
04:54	Seylerius	19 is... interesting.
04:54	Seylerius	Reimplement last.
05:45	Seylerius	http://sprunge.us/KYef
05:46	Seylerius	That's failing 4clojure #21: Nth Element
05:46	Seylerius	Oh, wait...
05:46	Seylerius	Nevermind
06:28	anti-freeze	Hey guys/girls. Does anyone have any issues with mongodb timing out?
06:29	deanm	Hello, can you please suggest an easy reading introduction to Clojure? I've tried a couple like braveclojure.com and "The Joy of Clojure" book but find it they move too fast for my understanding
06:33	anti-freeze	deanm: Maybe just clojure in action or programming clojure. I hear those are good. There's a new one soon to be released by o'reilly "Living clojure"
06:40	deanm	Thanks anti-freeze, ill have a look at them as well
06:46	anti-freeze	Sorry, my mac went to sleep. Did I miss anything?
06:48	deanm	anti-freeze: nope, other than me saying thanks for the tips
06:48	anti-freeze	deanm: Ah, now that I remember. Probably the best intro is clojure for the brave and true
06:48	anti-freeze	deanm: Its free online
06:49	deanm	anti-freeze: Yeah i tried that but at some point around destructuring i couldn't follow up and had to look up other references on the net so it occured to me that maybe im too dumb for that and need something more easy
06:50	anti-freeze	deanm: The thing with clojure is that it needs perseverance. Its frustrating at first
06:50	anti-freeze	deanm: It was easier for me coming from a ruby background, where it was sort of pseudo functional
06:51	deanm	anti-freeze: Ok nice to hear that, i come from a Java background although i don't program these days anymore
06:52	anti-freeze	deanm: That's probably why its frustrating. Check this out: http://steve-yegge.blogspot.com/2006/03/execution-in-kingdom-of-nouns.html
06:54	anti-freeze	Anyone with suggestions on the mongodb issue?
06:54	anti-freeze	T'was working yesterday, I swear it
07:12	anti-freeze	Also, how the hell do I access bounded variables from a macro. Say I have a macro that defines found-user from a DB query. I'm currently using found-user# gensyms, but I wan't access it. For example (if-valid-user params (login-success found-user))
07:21	Glenjamin	,`~'symbol
07:22	clojurebot	symbol
07:22	Glenjamin	anti-freeze: you can use ~'symbol inside the syntax-quote to get a bare symbole
07:23	Glenjamin	although in general it might be worth asking yourself if the macro provides any benefit over a function
07:24	anti-freeze	Glenjamin: Something like this? https://ideone.com/DjLZHZ I asked myself that, but it seems to provide more clarity
07:26	Glenjamin	(if-let [user (user-logged-in? params)] ...)
07:26	Glenjamin	you should be able to make that work with roughly the same code and no macro
07:26	Bronsa	anti-freeze: it's usually better to use gensyms rather than doing the ~' trick to get unqualified symbols
07:26	Glenjamin	maybe that should be called (logged-in-user params)
07:27	anti-freeze	Bronsa: I know, but i still want to access the found-user value to add his ID to session
07:28	Bronsa	anti-freeze: also you're trying to get runtime values at constant time
07:28	Bronsa	compile time*
07:28	anti-freeze	Bronsa: Well shit, how would you do it?
07:28	Glenjamin	the macro pasted is just some sugar for an if statement
07:28	anti-freeze	Ah, I give up...
07:29	Bronsa	anti-freeze: I'm talking about that cred/pass let. you don't seem to actually use those locals though
07:29	anti-freeze	Mongo doesn't work, I can't get simple authentication working...
07:31	Bronsa	anti-freeze: it's usually a good idea to have a solid understanding of how the language works before trying to write your own macros
07:31	anti-freeze	Bronsa: Yup, makes sense. I was swayed to clojure by all the preaching and what not of how amazing it is
07:32	Glenjamin	macros are a funny one, they're a headline language feature, but actually not used particularly often
07:32	Glenjamin	i overused macros quite a bit in my first clojure project
07:33	anti-freeze	How do I pass the then else branches then?
07:33	Glenjamin	just use a normal if form
07:33	anti-freeze	Glenjamin: Ah, makes sense
07:33	anti-freeze	makes cents?
07:36	Glenjamin	sense is correct
07:36	Glenjamin	something like this: https://www.refheap.com/98698
07:37	anti-freeze	Glenjamin: Yea, that's what I changed it to. Hold on, let me do some copypasta
07:38	anti-freeze	Glenjamin: https://www.refheap.com/7c95d4846cc402dccbf87c6c5
07:38	Glenjamin	yep, you can shrink it down a bit with some destructuring and more if-let, but thats the right idea
07:41	anti-freeze	Glenjamin: Alright man, thanks a bunch
10:12	anti-freeze	Hi again everyone. I can't seem to access the return values of mongodb insert operations. I just want to get the insert ID. Any ideas?
10:16	anti-freeze	Simply, is there a way to convert a monger WriteResult to a map?
10:19	gfredericks	anti-freeze: is a WriteResult a defrecord?
10:22	anti-freeze	gfredericks: Its a java class I think. I can't just reference properties with (:_id rec)
10:22	gfredericks	but monger is a clojure library?
10:23	gfredericks	have you tried clojure.core/bean?
10:25	anti-freeze	gfredericks: Just did, got me nowhere
10:31	justin_smith	anti-freeze: unrelated question - what exactly is the :flash key there?
10:31	anti-freeze	justin_smith: Flash key? There is none. I'm running tests and as part up setup I want to store a newly inserted users ID to check against the user ID stored in session
10:32	justin_smith	anti-freeze: I mean the :flash key on line 16 of https://www.refheap.com/7c95d4846cc402dccbf87c6c5
10:33	anti-freeze	justin_smith: a map containing errors and the previously passed parameters for dispatch to the view
10:33	justin_smith	anti-freeze: is putting stuff like that under a :flash key an idiomatic thing? is this related to the wrap-flash ring middleware?
10:34	anti-freeze	justin_smith: I don't know. I believe it is, yea
10:42	anti-freeze	Don't worry about the mongo thing guys, you're supposed to use insert-and-return. I don't know why that's not default behaviour, but ok
10:57	gfredericks	maybe insert is async?
10:58	gfredericks	I don't know nuthin bout mongo so I just assume it defaults to doing the fast-uncertain thing
10:58	justin_smith	gfredericks: yeah, I think so. Because nosql.
10:59	anti-freeze	I'm not sure. I'm just using it for the schemaless stuff
10:59	anti-freeze	One more question... for now. How would you test macros?
11:00	anti-freeze	Something like this: https://www.refheap.com/98704
11:01	gfredericks	write some tests that use them maybe
11:01	gfredericks	is the whole point of these to be anaphoric?
11:02	gfredericks	I don't think testing macros is too crucial unless they're really complicated
11:02	anti-freeze	gfredericks: Not really, its just that I was always writing (POST "/route" request (func request))
11:02	gfredericks	just test the code that uses them
11:02	justin_smith	anti-freeze: what's up with ~'request ?
11:03	justin_smith	oh
11:03	anti-freeze	justin_smith: I want to use the symbol request. So the result is (REQUEST-POST "/route" func) => (POST "/route" request (func request))
11:04	justin_smith	right, because you are generating a macro call with your macro
11:04	anti-freeze	justin_smith: Pretty much. I can't pass macros around unfortunately, or else I would have a REQUEST-* macro, which has the type of the request passed to it
11:05	anti-freeze	gfredericks: I guess the macros work just fine then
11:38	anti-freeze	Is anyone planning to implement an interactive clojure debugger by the way?
11:43	Igor	I run "lein uberjar" but it print "compiling" and that's all, jar doesn't appear
12:01	not-much-io	Hi all, I am trying to complete a HackerRank challenge with Clojure, but unfortunately my code is not cutting it speed wise. Using the time macro also didn't really show any bottlenecks.. Any suggestions? -> https://gist.github.com/KristoKoert/17ad1960ec2058388e63
12:02	Glenjamin	you can try using a profiler like Java VisualVM
12:03	not-much-io	I suppose it's as good a time as any to learn to use a profiler :)
12:20	Igor	I found solution - every code must be in functions
12:21	not-much-io	What do you mean?
12:23	not-much-io	It's purely a performance issue as I see it because about 5 test cases pass, however as the inputs get larger timeouts occur because the program won't finish under the 8s cap.
12:24	Igor	I try get uberjar, but it doesn't work until I delete code outside funcs declarations
12:25	not-much-io	Well yes because input-list isn't defined
12:26	not-much-io	I can't really trivially upload a workable uberjarrable example because the input is approx a miljon characters long.
12:26	Glenjamin	you're both talking about different problems.
12:27	justin_smith	isn't hackerrank the one where clojure always performs poorly because they include the clojure bootstrapping time in the perf timing?
12:28	not-much-io	Scala and Clojure are given extra time for that as I understand it.
12:28	justin_smith	oh, OK
12:28	not-much-io	But I saw that others had done the challenge in Clojure
12:29	justin_smith	it's not about jvm overhead though. It's about the clojure compiler bootstrap
12:29	justin_smith	OK
12:30	justin_smith	not-much-io: I think your keyword conversions are not needed
12:30	not-much-io	It's only a 10 point excercise so I was surprised my solution didn't pass the time constraints. Thought I had done something obviously stupid :)
12:30	justin_smith	just use the string as the key in the hash
12:31	justin_smith	not-much-io: also, yeah, every top level form should be a def/defn or some other similar declaration, not side effects and not regular code
12:31	justin_smith	for uberjar reasons, among other reasons
12:31	justin_smith	eg. loading a namespace should not have side effects
12:32	not-much-io	Yes I am aware of that, the outer expression was just to feed the results into the HackerRank engine.
12:32	not-much-io	Maybe I should not have included it, my bad.
12:32	not-much-io	Checking on the keyword conversion thing..
12:32	justin_smith	ahh, right, I was referencing your prior comment "I found solution - every code must be in functions"
12:33	justin_smith	not-much-io: only use keywords for literals in code (or what you expect the end user to provide as literals)
12:33	not-much-io	No, that wasn't me :D
12:33	justin_smith	if it's a string, it can stay a string
12:33	justin_smith	not-much-io: oops, my bad :)
12:34	not-much-io	Okey, but is it really that expensive of a converion? :O
12:34	not-much-io	I did it more for style than anything, but ofcourse it was pointless in this case
12:35	justin_smith	not-much-io: well I'd think it's a minus for style unless somebody is using the keywords as literals (which doesn't appear to be the case)
12:35	justin_smith	and yeah, repeated keyword conversions aren't super expensive, but they are not free either
12:36	not-much-io	Agreed that it's a minus
12:37	justin_smith	oh wow, I found a bug in criterium
12:37	justin_smith	lol
12:38	not-much-io	A bug?
12:38	justin_smith	Execution time mean : -3.551208 ns
12:38	justin_smith	I don't think there's such thing as code with a negative runtime
12:38	not-much-io	BTW there was a a conversion from char -> str -> keyword going on
12:39	justin_smith	oh wow, yeah, just use the char!
12:40	justin_smith	check out this silly benchmark https://www.refheap.com/98711
12:44	not-much-io	Unfortunately removing the conversions had no effect :(
12:44	justin_smith	have you tried profiling? jvisualvm is pretty accessible
12:44	justin_smith	sometimes just called visualvm
12:44	not-much-io	I was in the process of learning to use it, haven't used it before.
12:45	justin_smith	you should be able to find the cpu profiling tab
12:45	justin_smith	the issue after that is that it will show you stuff in terms of the jvm impl, not the clojure abstractions
12:46	not-much-io	Do I need to generate a uberjar to use it? I usually just use the repl for these kind of problems.
12:46	justin_smith	no, visualvm can connect to your repl
12:46	justin_smith	turn on cpu profiling, then run your main function
12:46	justin_smith	or whatever other function you want to profile in detail
12:47	justin_smith	you should get a clickable for each running jvm on the left side of the ui
12:47	not-much-io	Oooooh, thats all?
12:47	not-much-io	That was easy
12:47	justin_smith	yeah, it's easy, point and click
12:47	justin_smith	heh :)
12:47	not-much-io	Thanks! I would probabl have wasted a lot of time trying to use it :D
12:47	not-much-io	getMethods() are the mainusage
12:48	justin_smith	reflection!
12:48	justin_smith	try turning on reflection warnings vie project.clj
12:48	justin_smith	and fix the warnings
12:49	not-much-io	But wont that then show me something different than what runs on HackeRank?
12:49	justin_smith	the warnings tell you what you need to fix
12:49	justin_smith	once it's fixed, it's fixed regardless of where it runs
12:49	not-much-io	Do you mean the leinigen project.clj? Because I don
12:49	justin_smith	you use hints so that clojure doesn't need to use reflection to figure out which method to run
12:49	not-much-io	't even have a separate project
12:50	justin_smith	in that case, start up the repl with reflection turned on
12:50	justin_smith	just make sure warn-on-reflection is true, whatever method works for your repl
12:50	justin_smith	it's just convenient to do that from project.clj
12:51	not-much-io	Can I change it in a runnig repl?
12:51	justin_smith	I'm trying to think of how it's done, I haven't done it recently...
12:52	justin_smith	(set! warn-on-reflection true)
12:52	justin_smith	that will work for the current thread, and any agents / futures created from that thread
12:52	justin_smith	if you use Thread though, it might not propagate
12:53	not-much-io	Nope, no threading currently
12:53	not-much-io	okay, much less gets now
12:54	justin_smith	then run your code, and where you get reflection warnings, add hints about the actual type that will be seen at runtime
12:55	not-much-io	1. reflector.getMethods() 2. rule3.invoke() 3. PersistenArrayMap.assoc() 4. rule4.invoke()
12:56	not-much-io	Reflection still on maybe..
12:56	justin_smith	not-much-io: if you have reflection warnings turned on, then defining your functions should make the clojure compiler tell you where the reflection is happening
12:57	justin_smith	warn-on-reflection is about giving you guidance to where type hints are needed to speed up your code
12:57	justin_smith	it doesn't actually make anything faster by itself
12:57	not-much-io	So you are suggesting I add type hints?
12:58	justin_smith	not-much-io: that's how you make clojure not spend time in reflector.getMethods(), yeah
12:58	justin_smith	and that will often be the biggest perf gain you can get in a clojure program
12:58	not-much-io	Okey, now I understand.
12:58	not-much-io	Makes sense.
12:58	not-much-io	Thanks, learned alot. :)
12:58	justin_smith	this is especially true for math
12:59	justin_smith	where it can compile direct arithmetic ops for the correct type, instead of a bunch of reflection and generic math methods
12:59	not-much-io	Still I am surprised something simple like this requires type hints. EIther my algorithms sucks or the HackerRank people didn't bother with trying clojure. :)
13:00	justin_smith	not-much-io: if you want good performance, clojure requires type hints
13:00	not-much-io	Okey, so to reiterate: If the profiler shows me a lot of time spent in Reflector.getMethods() it's a reflection thing?
13:00	justin_smith	yes
13:01	justin_smith	and you can fix your code so that Reflector.getMethods() never gets called
13:01	J_Arcane	not-much-io: I'm finding that some of the online exercises for Clojure are a bit rubbish. Codewars' clj support is a mess.
13:01	justin_smith	reflection is very expensive
13:01	not-much-io	I though as much about the type hints, it's just it hasn't been a problem until now, even with much harder problems.
13:02	justin_smith	or, to be more explicit - code that requires reflection is very hard for the vm to optimize, and the reflection process itself is slow too
13:04	justin_smith	not-much-io: another thing that is going to add up over 100000 calls is the usage of a persistent data structure. If the code path is such that it wouldn't need copying, a simple four element array is going to speed things up a lot since so much of your code is just getting things from / updating values in that four element data structure
13:05	justin_smith	in general persistent data structures are awesome, but sometimes it can be safe to use a mutable thing, and it can be worth it for the 10x or more perf gain
13:05	justin_smith	that would also make your code uglier though
13:06	not-much-io	God damn it, sutpid question, how do you refer to someone in IRC :D
13:06	justin_smith	most clients will highlight usages of a nick
13:06	justin_smith	and will tab-complete a nick too
13:06	not-much-io	justin_smith Test
13:06	justin_smith	right, that highlights in my client
13:07	not-much-io	Okey
13:07	not-much-io	J_Arcane Probably the pains of a growing language :)
13:08	justin_smith	not-much-io: also the pains of a language that requires the full compiler to be loaded before code can be run
13:08	not-much-io	justin_smith Thanks for the tips, I'll certainly keep them in mind.
13:09	justin_smith	np - if you can eliminate reflection, and use a simple array in a tight loop when it's safe to do so, there's nothing keeping clojure from being at least as fast as java
13:09	J_Arcane	Argh. Could you repeat that? I missed it because my client crashed ...
13:10	not-much-io	justin_smith J_Arcane It's probably the pains of a growing language and justin_smith added that it's also a problem of a language that requires loading the full compiler.
13:10	not-much-io	Is reflection the main culprid for runtime speed?
13:10	J_Arcane	Yeah. The Clojure world in general does have a very 'beta' feel at times. :)
13:11	justin_smith	not-much-io: yeah, reflection followed by persistent data structure overhead. Never any reason not to eliminate the former, the latter is worth it for correctness unless you need that last 8-10x speed increase.
13:12	not-much-io	I wonder if HackerRank took Clojures startup time into account? I doubt it, iflooking at Clojure vs. Scala -> https://www.hackerrank.com/environment
13:13	not-much-io	justin_smith Awesome, that is worth knowing. I sort of did, but never really approached the problem :)
13:14	justin_smith	not-much-io: and typically your profiling will give you a good lead - whether you are spending a lot of time in reflection, in generic math ops, in persistent data structure allocations...
13:15	Bronsa	I kinda wish one had to allow the compiler to use reflection explicitly
13:15	justin_smith	Bronsa: oh, that's a great idea for a feature
13:15	justin_smith	(set! warn-on-reflection :pedantic)
13:15	justin_smith	haha
13:16	not-much-io	As I've looked around, it seems a lot of peole are discontent that clojure is dynamically typed..
13:16	hyPiRion	I'd like the compiler to detect uniqueness and do transient magic on the persistent data structures.
13:16	Bronsa	justin_smith: wouldn't make much sense to add that but not make it the default
13:16	hyPiRion	But the persistent data structures are actually very good performance wise, really.
13:16	justin_smith	Bronsa: I don't think it would fly unless it was opt-in though
13:17	Bronsa	justin_smith: right, it's too late to change that in clojure unfortunately, I guess
13:17	justin_smith	hyPiRion: it's true, but I've also seen the difference a switch to an array in a tight loop can make (because of the mixture of eliminating allocation + cache coherence)
13:18	justin_smith	for primitive types that is
13:18	Bronsa	btw clojure doesn't really need the whole compiler to run code -- when it AOTs it just needs the runtime
13:18	justin_smith	Bronsa: but being able to turn it on for my own code would be great
13:18	justin_smith	Bronsa: but will it actually run without loading the compiler from AOT ?
13:18	hyPiRion	justin_smith: yeah, true enough.
13:18	Bronsa	justin_smith: would it help you more than (set! warn-on-reflection true)?
13:18	justin_smith	Bronsa: I thought the compilation stuff would be loaded regardless
13:19	justin_smith	Bronsa: maybe not
13:19	justin_smith	Bronsa: also, in the context of the code challenge there, I don't think they let you submit an uberjar? not sure though.
13:20	Bronsa	justin_smith: what i mean is, once you AOT compile clojure.lang.Compiler is not necessary anymore as there's no clj compilation involved while loading
13:20	not-much-io	justin_smith Not in HackerRank no
13:21	justin_smith	Bronsa: OK. So unless your own code causes it to be loaded at runtime, it won't be.
13:21	justin_smith	I guess I should have ended that with a question mark, as it was a question :)
13:39	not-much-io	justin_smith: Reporting back, with typ hints to Math/abs performance increase of ~8 times :)
13:45	gfredericks	~reflection
13:45	clojurebot	Excuse me?
13:47	chenglou	why doesn't this terminate? (def a (range)) (def b (rest a)) (def c (rest a)) (= b c)
13:47	not-much-io	(range) is a infinite sequence
13:48	chenglou	yes, but I thought b and c were just pointers to the same "next" slot in a
13:48	not-much-io	although, you don't seem to be forcing evaluation..
13:49	not-much-io	No, rest takes the whole remaining sequence (infinity - the first) :)
13:49	not-much-io	When you compare them, they are evaluated
13:49	chenglou	well, I thought at one point you'd hit a pointer equality when you compare both streams
13:50	chenglou	just like you would, trying to deeply compare two trees
13:50	not-much-io	Clojure does not compare pointers, it compares values
13:51	chenglou	it does pointer comparison first though
13:51	not-much-io	Oh, sorry I am misinformed then.
13:51	chenglou	otherwise (= a a) would get stuck
13:51	not-much-io	Is it comparing the pointers of the list or the element?
13:52	chenglou	I guess the element, which is why my example doesn't terminate
13:52	not-much-io	Would seem that way.
13:52	chenglou	which is why I wonder it doesnt do it for the list, since it does something like that for subtrees for the other 3 collection types
13:53	not-much-io	It's actually a lazyseq
13:53	not-much-io	(type (range))
13:55	not-much-io	lazyseq might be a special case because it can be infinitely big. However I am just speculating. :)
13:55	chenglou	it can
13:55	chenglou	but I guess this example makes slightly more sense:
13:55	chenglou	(def a (range)) (def b (rest a)) (def c (cons 1 (nnext a)))
13:55	chenglou	then (= b c)
13:56	chenglou	you'd think that while going through the list it'd compare the list pointer first, hit the element 1, deeply compare, hit the rest of the list
13:56	not-much-io	I mean I am speculating about whether or not it is a special case implementation wise.
13:56	chenglou	then see the rest of the list point to the same place in a
13:56	not-much-io	I would think that (rest myseq) would return a new sequence
13:57	not-much-io	Clojure data structures are immutable
13:58	chenglou	yes I get that, but I was wondering why it didn't do it like this: "b's first cell is a new item, b's second third fourth... just point to that chunk in a"
13:58	not-much-io	(rest a) (conj a 1) etc. all create a new datastructure, though they reuse the old ones elements (for performance) it would make sense to consider them different
13:58	chenglou	it does, but I'm not explainining this correctly
14:00	not-much-io	As I understand you are surprised that two different datastructures with "shared" (as in under the hood shared) elements are not equal in term of pointers
14:00	dnolen	chenglou: it could probably behave the way expect, but sequence equality tests is eager on elements of the sequence, it doesn't special case equality testing of the tail
14:01	dnolen	s/the way/the way you expect
14:02	chenglou	dnolen: I see. But does it make sense conceptually to compare the tail? Disregarding the perf benefits
14:02	chenglou	like, should my above example be allowed:
14:02	chenglou	`(def a (range)) (def b (rest a)) (def c (cons 1 (nnext a))) (= b c)`
14:02	chenglou	certainly works for all the other collections
14:05	chenglou	not-much-io: yeah I guess. I got that expectation from all other collections
14:12	Bronsa	chenglou: the problem there is that calling rest on (range) returns a new value each time
14:14	Bronsa	chenglou: if you replace (rest) with (iterate inc 0), it will terminate
14:15	chenglou	Bronsa: right. But calling (conj a 1) also returns a new value, for a vector a
14:16	chenglou	If I'm not mistaken you could do (= (conj a 1) (conj a 1)) and it'll do pointer comparison for the a subtree
14:17	Bronsa	chenglou: clojure will do pointer comparison before doing value checks, this is why (def a (iterate inc 0)) (= (rest a) (rest a)) returns true in constant time
14:19	chenglou	Bronsa: what I was asking for is why lazy seqs didn't do tail comparison before cell comparison. Which dnolen said isn't implemented (yet? Or will never be? Dunno)
14:19	Bronsa	chenglou: because of implementation details in (def a (range)) (def b (rest a)) (def c (rest a)) b and c will never have an identical pointer
14:19	justin_smith	~range
14:19	clojurebot	excusez-moi
14:19	Bronsa	this has to do with range being a chunked-seq
14:21	Bronsa	= isn't chunk-aware
14:21	justin_smith	~range is \|reply\| because range is a chunked-seq.
14:21	clojurebot	c'est bon!
14:21	justin_smith	~range
14:21	clojurebot	range is \|reply\| because range is a chunked-seq.
14:21	justin_smith	argh!
14:21	justin_smith	clojurebot: forget range
14:21	clojurebot	Huh?
14:21	justin_smith	ugh
14:22	justin_smith	~forget range
14:22	clojurebot	I don't understand.
14:23	Bronsa	chenglou: what you described is how lazy-seq do work. this is why it works for (iterate inc 0). (range) is a special type of lazy-seq, backed by a chunked-seq as opposed to a normal seq, the tails will never be identical
14:25	amalloy	clojurebot: forget range is \|reply\| because range is a chunked-seq.
14:25	clojurebot	I forgot that range is reply because range is a chunked-seq.
14:25	justin_smith	thanks
14:25	amalloy	clojurebot: range is <reply> because range is a chunked-seq.
14:25	clojurebot	c'est bon!
14:25	amalloy	~range
14:25	clojurebot	range is \|reply\| because range is a chunked-seq.
14:25	amalloy	uuuugh
14:25	justin_smith	~clojurebot
14:25	clojurebot	clojurebot is a weirdo
14:26	amalloy	clojurebot: clojurebot is like an elephant: he never forgets a useless factoid
14:26	clojurebot	Roger.
14:26	chenglou	Bronsa: I see. I'll think a bit more about this, thanks
14:29	Bronsa	chenglou: I just looked at the lazy-seq source and it looks like I'm partially wrong, there's no pointer-equality check on the tails. I apologize
14:30	Bronsa	agreed this somewhat is surprising
14:31	chenglou	Bronsa: ah. Well tldr: I was wondering if value comparison of infinite lazy seqs should even be allowed (say, for get-in a value with a lazy seq key in a map)
14:31	justin_smith	Bronsa: then why is it that ##(let [n (iterate inc 0)] (= (rest n) (rest n))) works?
14:31	lazybot	⇒ true
14:31	chenglou	if it's a map of vector -> int in the worst case I retrieve the int using a different vector and I only pay a small price for deep equality check on the key
14:31	chenglou	but with lazy seq it's not just a small perf cost. It might loop forever
14:31	justin_smith	chenglou: well, there is no marker to tell you if a lazy seq terminates
14:32	ane	does requiring a namespace with :refer :all not import the defrecords
14:32	justin_smith	ane: require doesn't import classes
14:32	Bronsa	justin_smith: because = does pointer equality
14:32	chenglou	justin_smith: yes which is why I was thinking if conceptually you should just claim that you don't guarantee that behaviour at all (retrieving value in a map using a lazy seq, with value comparison)
14:32	justin_smith	Bronsa: oh, OK
14:33	Bronsa	justin_smith: the issue is with e.g. (let [n (iterate inc 0)] (= (cons 1 (rest n)) (cons 1 (rest n)))
14:33	justin_smith	ane: use :import for classes
14:33	justin_smith	Bronsa: ahh! OK
14:33	ane	justin_smith: oh yes. what's the best approach in tests? that?
14:33	Bronsa	which would work if lazy-seq used = internally, but they don't
14:33	Bronsa	they just invoke .equals skipping the pointer check
14:33	Bronsa	https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/LazySeq.java#L120-L121
14:33	justin_smith	ane: sure, or just use the class fully qualified with package, importing is just a syntax convenience
14:34	justin_smith	Bronsa: thanks, now I get it
14:34	ane	justin_smith: oh, bloody hell, yes
14:35	tolstoy	Anyone having issues with the latest cider snapshot? No repl appears.
14:36	justin_smith	tolstoy: did you delete all your elc files? when you upgrade cider versions your elc files are invalid
14:36	justin_smith	common cause of cider pain
14:36	tolstoy	Yeah, let me double check. My last version was 8.2. Didn't see anything odd over there (8.2 dir is gone).
14:36	justin_smith	caused by the fact that cider abi is a moving target, and elisp doesn't compile in a way that handles that nicely
14:37	justin_smith	tolstoy: this isn't just about cider elc files, it can be effected by eg. clojure mode elc files too in my experience
14:37	justin_smith	and of course you also need to restart emacs after a cider version upgrade
14:38	tolstoy	I do that the first sign of trouble. I learned at least one thing from using Windows in 1999 for six months!
14:38	justin_smith	haha
14:39	tolstoy	Works now (just killed ALL elpa stuff), but get: WARNING: CIDER requires nREPL 0.2.7 to work properly
14:39	justin_smith	tolstoy: did you upgrade your cider-nrepl dep to match your new cider.el version?
14:40	tolstoy	Ah, probably some other dep is pulling that in.
14:40	tolstoy	Yeah. Snapshot.
14:40	justin_smith	snapshots are by default only fetched daily, but there is a way to force update sooner
14:40	justin_smith	which I don't recall off the top of my head...
14:41	tolstoy	rm -rf ~/.m2
14:41	tolstoy	:)
14:42	justin_smith	yes, there is always the nuclear option, but there is a more elegant way to do it as well
14:42	tolstoy	lein -U?
14:43	tolstoy	Well, I only moved to the 0.9.0-snapshot today, so I'm not sure were the nrepl dep is. tools-nrepl?
14:44	justin_smith	oh, I don't know then - there is a way to look at the plugin deps tree
14:47	tolstoy	lein deps :tree reveals all, but I do't see a dep for nrepl with cider-nrepl. However, it does show up as a top level dep.
14:47	justin_smith	tolstoy: could be your lein version injecting it?
14:47	tolstoy	Yeah.
14:48	Bronsa	chenglou: FYI I'm opening a ticket with a patch that introduces the pointer check in seq comparison
14:54	tolstoy	justin_smith: Interesting. Although cider-nrepl (according to its project.clj file) requires 0.2.7, lein somehow does something to remove it and inject its own nrepl as a top-level dep.
14:54	pandeiro	tolstoy: you need to specify tools.nrepl in :dev :dependencies
14:54	tolstoy	Maybe that makes sense.
14:55	pandeiro	i don't understand lein well enough to know why :dev :dependencies take precedence over :dependencies
14:55	justin_smith	tolstoy: try providing it as a top level dep in your profiles.clj
14:55	pandeiro	maybe that is intuitive, i don't know
14:55	justin_smith	pandeiro: it's because ones a top level dep, and the other is transitive
14:55	pandeiro	the fix for this is known, hyPiRion posted it
14:55	justin_smith	top level takes precedence
14:55	pandeiro	both should be top level?
14:56	justin_smith	pandeiro: not if one is coming from cider
14:56	justin_smith	that's why the fix is to explicitly specify the dep on your own top level
14:56	pandeiro	justin_smith: nope not what i'm saying
14:56	pandeiro	specifying in your own top level doesn't fix it
14:56	pandeiro	specifying it in your own top level :dev does
14:56	pandeiro	which to me is sort of odd
14:56	justin_smith	that's weird
14:57	tolstoy	Yeah, making it a dep of the :dev profile "solves" it.
14:57	pandeiro	link: https://github.com/technomancy/leiningen/issues/1840
14:57	pandeiro	black magic
14:57	hyPiRion	both are top level, but you shouldn't add tools.nrepl as a project dep only because you need the latest cider
14:57	pandeiro	hyPiRion: adding as non-dev does not fix
14:57	justin_smith	hyPiRion: profiles.clj :dev dep, of course
14:58	justin_smith	pandeiro: I think that is because of how profiles are merged and the effective profile is generated
14:58	justin_smith	a :dev dep overrides a regular dep
14:58	pandeiro	justin_smith: right, i imagined a merge was happening
14:58	hyPiRion	oh, yeah no, that's not happening. That'd be bad for repeatability
14:59	pandeiro	hyPiRion: what would be bad for repeatability?
14:59	pandeiro	being able to specify a project's tools.nrepl version explicitly?
14:59	hyPiRion	merging stuff from .lein/profiles.clj into the project.clj on dupe profiles
15:00	pandeiro	which one wins in the case profiles.clj has one :dev version and project has another?
15:00	hyPiRion	the most local one
15:01	pandeiro	project -> dep is less local than profiles -> :dev ?
15:01	tolstoy	I think the profiles.clj one wins. I just had that issue with an old lein-ancient.
15:01	hyPiRion	project.clj ← local profiles.clj ← user profiles.clj ← system profiles.clj
15:01	tolstoy	Speaking of which, tools.nrepl "0.2.8" is available.
15:02	gfredericks	with one less reflection warning :)
15:03	hyPiRion	But there is a regression related to transitive dependencies on tools.nrepl. The fix is going to be in 2.5.2
15:03	hyPiRion	just fyi
15:03	Bronsa	chenglou: http://dev.clojure.org/jira/browse/CLJ-1679
15:26	chenglou	Bronsa: woohoo thanks!
15:30	seangrove	Bronsa: Very nice
16:42	Mandar	Hello!
16:42	Mandar	I'm playing with transducers.
16:43	Mandar	Is this code idiomatic? http://pastie.org/private/vgbhlsx0ugxpsfdorfajw
16:44	Mandar	is there any better way to do null punning?
16:50	tomjack	if I was forced to do that for some reason, I'd consider def'ing a (fn [f] (fn [arg] (if (nil? arg) nil (f arg)))) separately
16:51	tomjack	then (map (letting-nils-be f)) or whatever
16:52	tomjack	(map #(cond-> % (some? %) f)) ?
16:53	tomjack	basically it would generally seem un-idiomatic to me to define a special map which just modifies f, instead of passing a modified f to map
16:54	Mandar	tomjack: thank you
16:54	tomjack	if some particular case comes up a lot in a development, maybe makes sense, though (e.g. I guess keep came up enough in general clojure code to be added)
16:56	tomjack	I guess your transducer may be dual to keep?
16:56	Mandar	I don't really know. Basically, I'm trying to avoid null pointer exceptions.
16:57	tomjack	(for amusement, I'm trying to think of an analogous name -- "leave"?)
16:57	Mandar	it's close to a Maybe, but I'm a FP newbie
16:58	Mandar	basically, I tried to reimpliment this behaviour: https://github.com/clojure/algo.generic/blob/master/src/main/clojure/clojure/algo/generic/functor.clj
16:58	Mandar	but with transducers
17:03	tomjack	either your custom transducer or just modifying the fn passed to map seem reasonable to me. if you go with a custom transducer, I guess it might be idiomatic to also provide the other arities for seqs, like clojure.core/map
17:03	tomjack	dunno
17:03	tomjack	maybe future libs will tend to drop that, and it's just there for backwards compat
17:04	tomjack	I'd guess people will do it when it's easy
17:04	tomjack	for something used not-too-often I'd prefer just calling map, because everyone knows what that means already
17:05	gfredericks	tomjack: #(cond-> % (some? %) f)) ===> #(some-> % f)
17:05	tomjack	oya!
17:06	tomjack	Mandar: ^
17:06	Mandar	tomjack, gfredericks: thanks!
17:06	tomjack	I still am not on great terms with the new arrows
17:06	Mandar	I don't understand this code yet
17:06	Mandar	I rewrote mine with a my-nil-pun fn
17:07	gfredericks	tomjack: I just yesterday realized I could use as-> at the end of a normal threading form to give the thing a name and do more complex stuff with it
17:07	tomjack	I think part of the reason I tend to avoid them is that I'm scared of all the unknown possibilities :)
17:07	Mandar	the only problem I see with this approach is the need to "protect" all the functions in the comp
17:07	Mandar	"protect" meaning wrap them with my-nil-pun
17:08	Mandar	doing a custom transducer lets me avoid that, but I don't know if it's a bad practice
17:08	tomjack	nah, if you're using it a lot, go for it, I think
17:09	gfredericks	well up
17:09	gfredericks	um
17:09	gfredericks	I mean
17:09	tomjack	s/think/opine/ :)
17:09	gfredericks	you don't have to think of it as writing your own transducer
17:09	gfredericks	(defn leave [f & args] (apply map #(some-> % f) args))
17:09	tomjack	:/
17:09	gfredericks	it's just a modification of map
17:10	tomjack	oh, you're targetting 1 and 2-arities?
17:10	gfredericks	and etc
17:10	gfredericks	3, 4, even 5
17:10	tomjack	but #(some-> % f) is 1-ary
17:11	gfredericks	okay not 3, 4, nor even 5
17:11	tomjack	but yeah, nice :)
17:11	gfredericks	I wonder if I can pass an infinite number of args to map
17:11	Mandar	gfredericks: your code is not using transducers anymore, is it?
17:11	gfredericks	Mandar: sure it is, because map does
17:12	Mandar	sorry, doing my best! :)
17:12	gfredericks	,(apply map #(first %&) (repeat (range 5)))
17:12	clojurebot	eval service is offline
17:12	tomjack	better idea to sacrifice clojurebot than my emacs responsiveness :(
17:12	gfredericks	&(apply map #(first %&) (repeat (range 5)))
17:12	Mandar	haha
17:13	oddcully	clojurebot: this is an outrage!
17:13	clojurebot	In Ordnung
17:14	justin_smith	~this
17:14	clojurebot	this was discussed in a loud bar
17:15	gfredericks	~I
17:15	clojurebot	I will never forgive constantly polluting useful triggers like ~anyone by learning other irrelevant factoids to repeat instead
17:15	gfredericks	~I
17:15	clojurebot	I will never forgive dumb
17:15	gfredericks	man me neither
17:16	tomjack	:)
17:23	Mandar	thank you very much guys
17:42	benjyz1	hi. quick question. how do I get "bar" out of this structure: {"foo" {"bar" 266}}
17:46	oddcully	benjyz1: (get-in {"foo" {"bar" 266}} ["foo" "bar"])
17:46	TEttinger	that will get the value associated with bar
17:47	benjyz1	thx. I'm a bit confused. this is an arrayhashmap, correct?
17:47	TEttinger	it's usually called a map
17:47	TEttinger	,(def foobar {"foo" {"bar" 266}})
17:47	clojurebot	#'sandbox/foobar
17:48	oddcully	,(get-in {"foo" {"bar" 266}} ["foo" "bar"])
17:48	TEttinger	,(val foobar)
17:48	clojurebot	266
17:48	clojurebot	#error{:cause "clojure.lang.PersistentArrayMap cannot be cast to java.util.Map$Entry", :via [{:type java.lang.ClassCastException, :message "clojure.lang.PersistentArrayMap cannot be cast to java.util.Map$Entry", :at [clojure.core$val invoke "core.clj" 1506]}], :trace [[clojure.core$val invoke "core.clj" 1506] [sandbox$eval54 invoke "NO_SOURCE_FILE" -1] [clojure.lang.Compiler eval "Compiler.java" 6...
17:48	TEttinger	the error was mine
17:48	oddcully	now it belongs to all of us
17:48	TEttinger	heh
17:49	TEttinger	if you want to specifically get the key "bar"
17:49	TEttinger	returning "bar", without knowing what key is there beforehand...
17:50	TEttinger	,(-> foobar get "foo" keys)
17:50	clojurebot	#error{:cause "java.lang.String cannot be cast to clojure.lang.IFn", :via [{:type java.lang.ClassCastException, :message "java.lang.String cannot be cast to clojure.lang.IFn", :at [sandbox$eval95 invoke "NO_SOURCE_FILE" 0]}], :trace [[sandbox$eval95 invoke "NO_SOURCE_FILE" 0] [clojure.lang.Compiler eval "Compiler.java" 6784] [clojure.lang.Compiler eval "Compiler.java" 6747] [clojure.core$eval invo...
17:50	TEttinger	,(-> foobar (get "foo") keys)
17:50	clojurebot	("bar")
17:50	TEttinger	,(-> foobar (get "foo") ffirst) ; if there is only one
17:50	clojurebot	"bar"
17:51	oddcully	i guess you take this way much to verbatimn
17:52	TEttinger	I've had cases where I want a key out of a data structure before
17:52	oddcully	OP was way unclear
17:52	TEttinger	yep
17:54	benjyz1	thx, got it.
17:54	TEttinger	get-in is great though
17:56	benjyz1	maybe another question :) what would be the easiest way to update a variable via an agent..
17:57	benjyz1	I have a function which calls a remote resource, and I want to have the update run once every second
17:57	TEttinger	most of the time clojure code doesn't need agents, though sometimes it really does
17:59	TEttinger	http://clojuredocs.org/clojure.core/agent start here I guess with the examples, I need to refresh my memory on this
17:59	benjyz1	I see. still trying to wrap my around refs and agents
17:59	TEttinger	atoms are nice and simple
17:59	justin_smith	benjyz1: an agent is a variable
17:59	justin_smith	benjyz1: it holds a value, you send it a function that updates it
18:00	justin_smith	TEttinger: they are simple, but not so great for things that require side effects in generating the value
18:00	TEttinger	ah
18:00	benjyz1	and starting a thread to update that state would be non-idiomatic?
18:01	justin_smith	benjyz1: sending to an agent uses the agent thread pool
18:01	justin_smith	benjyz1: in other words, it's already going to do the work in another thread
18:02	justin_smith	TEttinger: for example, if you were to use a request to a remote resource to update a value in an atom, retries would be a significant cost, so an agent matches that scenario more closely I think
18:03	TEttinger	ah ok
18:04	justin_smith	the maximum number of retries, worst case, is the factorial of the overlaps
18:04	justin_smith	so three overlapping changes could result in 6 calculations, 4 in 24 calculations, etc.
18:05	justin_smith	I think...
18:34	javjarfer	hi! Anyone can explain me why (map list {:1 1 :2 2} {:3 3 :4 4}) evaluates to (([:1 1] [:4 4]) ([:2 2] [:3 3]))??
18:34	lazybot	javjarfer: What are you, crazy? Of course not!
18:35	justin_smith	javjarfer: what did you expect it to do?
18:35	justin_smith	,(map list [:a :b :c] [:d :e :f])
18:35	clojurebot	((:a :d) (:b :e) (:c :f))
18:36	TEttinger	maps are unsorted, so that could be one source of confusion
18:36	javjarfer	justin_smith, (([:1 1] [:3 3]) ([:2 2] [:4 4]))
18:36	TEttinger	try using sorted-map there
18:37	hyPiRion	maps don't have any ordering by default.
18:37	TEttinger	(map list (sorted-map :1 1 :2 2) (sorted-map :3 3 :4 4))
18:37	TEttinger	,(map list (sorted-map :1 1 :2 2) (sorted-map :3 3 :4 4))
18:37	clojurebot	(([:1 1] [:3 3]) ([:2 2] [:4 4]))
18:37	javjarfer	ahhhh, i see... thanks you so much, it was driving my crazy
18:37	TEttinger	there's also ordered from flatland
18:38	TEttinger	$google flatland/ordered clojure
18:38	lazybot	[flatland · GitHub] https://github.com/flatland
18:38	TEttinger	https://github.com/flatland/ordered
18:39	javjarfer	so, i think probably the third example from here: "https://clojuredocs.org/clojure.core/doseq" should be changed
18:42	TEttinger	javjarfer, that's a good catch
18:43	javjarfer	TEttinger, thank you! First contribution xD
18:44	TEttinger	(inc javjarfer)
18:44	lazybot	⇒ 1
18:44	TEttinger	you has a karma, protect it, nurture it
18:44	TEttinger	(identity dnolen)
18:44	lazybot	dnolen has karma 21.
18:44	TEttinger	(identity amalloy)
18:44	lazybot	amalloy has karma 239.
18:45	javjarfer	TEttinger, ei! love that, there is a long way ahead
18:55	justin_smith	(identity justin_smith)
18:55	lazybot	justin_smith has karma 217.
19:11	justin_smith	,(->> (all-ns) (mapcat (comp vals ns-interns)) (filter (comp :test meta)))
19:11	clojurebot	()
19:11	justin_smith	still proud of that one-liner
19:12	justin_smith	(it will list all defined clojure.test tests)
19:15	TEttinger	&(let[a #(apply str(flatten %))r repeatedly R repeat p #(partition %(a(R %2 %3)))N rand-nth n #(a(N(concat(R %"")(mapcat p[1 1 2 2][13 5 8 2]%&))))v #(n 0"aioe""u""aiioieoa")w(fn[](let[s[(n 0"JYZKVGSMNPRH"""(a(for[V"EA"C"zkbhhmlrd"](str V C)))"")(r(N[1 1 2])#(do[(v)(n 0"zkssgnmpbhhll""dt""shth")]))]](a s)))Y(r 500 w)](a[(mapv(fn[u d](str u" "(N["begat""sired"])" "d". Then "))Y(rest Y))(last Y)" begat Rich, Amen."]))
19:15	lazybot	⇒ "Mop sired Yib. Then Yib sired Elab. Then Elab begat Posok. Then Posok begat Gais. Then Gais begat Alieth. Then Alieth begat Yab. Then Yab begat Nam. Then Nam sired Zietah. Then Zietah begat Hail. Then Hail sired Sem. Then Sem begat Rioh. Then Rioh begat Koag. Then K... https://www.refheap.com/98743
19:15	justin_smith	haha, nice
19:17	TEttinger	http://ideone.com/zwnFAL is less obfuscated, it's used to generate english-like planet names for a friend's scifi game
19:17	TEttinger	it's meant to generate 10K unique names, but it runs out of memory on ideone if you try 10K there
19:17	TEttinger	it works fine locally
19:17	TEttinger	lazyseqs are awesome here
19:18	TEttinger	I generate an infinite list and call distinct on it, then take 10000
19:28	celwell	What's the best way to deref an atom from another namespace? @(resolve 'purple.dispatch/zq)
19:28	gfredericks	@purple.dispatch/zq
19:28	celwell	@dispatch/zq doesn't work
19:29	celwell	ah hmm thanks
19:29	gfredericks	how does it fail?
19:29	celwell	ill try the one you said
19:29	clojurebot	No entiendo
19:29	gfredericks	you can (:require [purple.dispatch :as dispatch])
19:29	gfredericks	if you want to use dispatch/zq
19:30	celwell	Well i am requiring dispatch, but @dispatch/zq failed. I'll try again
19:31	justin_smith	celwell: what is the error you get
19:32	celwell	java.lang.ClassCastException
19:32	celwell	clojure.lang.PersistentArrayMap cannot be cast to java.util.concurrent.Future
19:32	celwell	maybe it's unrelated
19:32	justin_smith	OK, you tried to deref a map
19:32	justin_smith	,@{}
19:32	clojurebot	#error{:cause "clojure.lang.PersistentArrayMap cannot be cast to java.util.concurrent.Future", :via [{:type java.lang.ClassCastException, :message "clojure.lang.PersistentArrayMap cannot be cast to java.util.concurrent.Future", :at [clojure.core$deref_future invoke "core.clj" 2184]}], :trace [[clojure.core$deref_future invoke "core.clj" 2184] [clojure.core$deref invoke "core.clj" 2205] [sandbox$ev...
19:32	justin_smith	see, same error
19:32	celwell	oh, yeah i forgot i changed the strucutre of that atom, let me try again
19:36	celwell	ok, nvm...
19:38	Lewix	hello
19:39	justin_smith	greetings and salutations
19:41	arrdem	$GREETING
19:42	justin_smith	TEttinger: "It Came from Planet Cough"
19:44	justin_smith	TEttinger: I shared your planet generator with a friend, who discovered some dictionary words
19:44	justin_smith	also, "Chestoid must be where xenomorphs are from"
19:46	TEttinger	haha
19:47	justin_smith	"it's the fourth planet it the Chan system, best known for the troll-like hominids and their obsession with memes"
19:47	TEttinger	nice
19:47	justin_smith	another good one from that list: "Tom"
19:47	clojurebot	Titim gan éirí ort.
19:48	TEttinger	I managed to parse out most if not all the swears
19:48	justin_smith	nice
19:48	TEttinger	Abbo keeps getting through, which is a slur for aboriginal people, typically australian
19:49	justin_smith	Ted is another one
19:49	TEttinger	I'm sure there's more ethnic slurs that it generates, clojure is such a racist generator
19:49	justin_smith	"the journey to planet Suck"
19:50	justin_smith	oh wow, "Foo" is in there
19:53	gfredericks	PSA: you can generate things from a regex with https://github.com/gfredericks/test.chuck#string-from-regex
19:54	arrdem	gfredericks: nice!
19:55	TEttinger	wow https://github.com/gfredericks/test.chuck/blob/master/resources/com/gfredericks/test/chuck/regex.bnf
19:55	TEttinger	(inc gfredericks)
19:55	lazybot	⇒ 124
19:56	Seylerius	TEttinger: That a clojure karma system?
19:56	arrdem	Seylerius: yep
19:56	TEttinger	yep
19:56	Seylerius	Shiny.
19:56	arrdem	(inc gfredericks)
19:56	lazybot	⇒ 125
19:56	arrdem	(identity arrdem)
19:56	lazybot	arrdem has karma 40.
19:56	arrdem	I need to lurk more
19:56	gfredericks	TEttinger: I learned a lot of disgusting things about jvm regexes while building that
19:56	TEttinger	(identity tekacs)
19:56	lazybot	tekacs has karma 0.
19:57	TEttinger	(identity TEttinger)
19:57	lazybot	TEttinger has karma 44.
19:57	TEttinger	gfredericks, I remember
19:57	TEttinger	stuff like the && grouping within [] right?
19:57	gfredericks	yeah that's the second worst
19:58	TEttinger	there's WORSE?
19:58	arrdem	there's always something worse
19:59	gfredericks	the worst thing I know of is that you can put a \Q\E virtually anywhere in a regex and it's a noop, even in the middle of things that should never be broken up
20:00	gfredericks	e.g.
20:00	gfredericks	&(re-matches #"\p{Alpha}+" "hello")
20:00	lazybot	⇒ "hello"
20:00	gfredericks	&(re-matches #"\p{Al\Q\Epha}+" "hello")
20:00	lazybot	⇒ "hello"
20:01	TEttinger	aaaaaagh
20:01	hyPiRion	omg what
20:02	arrdem	ew
20:02	justin_smith	gfredericks: oh my god that's an atrocity
20:02	justin_smith	it's like, war crime level stuff
20:03	gfredericks	there are some things you never want to have to tell your kids about
20:04	TEttinger	it's like \p{Ol} \p{Ot}
20:05	justin_smith	gfredericks: it seems the only rule is that one \Q\E can't be in the middle of another one
20:06	justin_smith	,(re-matches #"\p{Al\Q\Q\E\Epha}+" "hello")
20:06	clojurebot	#<SecurityException java.lang.SecurityException: denied>
20:06	justin_smith	,(re-matches #"\p{Al\Q\E\Q\E\Q\Epha}+" "hello")
20:06	clojurebot	"hello"
20:07	hyPiRion	,(re-matches #"\p{\QAlEpha\E}+" "hello")
20:07	clojurebot	#<NoClassDefFoundError java.lang.NoClassDefFoundError: Could not initialize class java.util.regex.PatternSyntaxException>
20:07	hyPiRion	,(re-matches #"\p{\QAlpha\E}+" "hello")
20:07	clojurebot	"hello"
20:07	hyPiRion	oh okay then
20:08	gfredericks	justin_smith: right
20:08	hyPiRion	gfredericks: but \Q can be inside a \Q, right?
20:08	gfredericks	oh I didn't expect that one o_O
20:08	gfredericks	yes it can
20:09	gfredericks	,(re-matches #"\p\{\A\l\p\h\a}+" "hello")
20:09	clojurebot	#<NoClassDefFoundError java.lang.NoClassDefFoundError: Could not initialize class java.util.regex.PatternSyntaxException>
20:09	gfredericks	&(re-matches #"\p\{\A\l\p\h\a}+" "hello")
20:09	lazybot	java.util.regex.PatternSyntaxException: Unknown character property name {\} near index 2
20:09	gfredericks	&(re-matches #"\p{\A\l\p\h\a}+" "hello")
20:09	lazybot	java.util.regex.PatternSyntaxException: Unknown character property name {\A\l\p\h\a} near index 13
20:09	gfredericks	that should be equivalent afaik
20:09	gfredericks	er
20:09	gfredericks	maybe I'm confused
20:09	hyPiRion	well apparently not
20:09	hyPiRion	although I would agree with you
20:09	gfredericks	gotta put a baby to bed
20:17	underplank	Hey all. Im using clj-http to build some unit tests. I have a route that Im wanting to make sure it returns a 404, but it seems like clj-http throws an exception. Is there a way I can get clj-http to not throw that exception?
20:18	underplank	ahh found it. {:throw-exception false}
20:18	underplank	should probably read the documentation
20:24	jeremyheiler	underplank: sometimes i wish that was the default
20:25	underplank	yeah… coming from python with the requests library where that is the default it is rather nice. I dont really like being forced into throwing an exception. But I guess you could argue that it forces good behaviour.
20:26	jeremyheiler	underplank: good behavior? eh. apis do waht apis do. hard to manage servers outside of your control
20:27	underplank	yeah…. thats very true. Its only good behaviour if you control both ends of the request. I get the feeling its a javaesque thing that managed to work its way into clj-http
20:27	underplank	shrugs at least there is a way out of it.
20:27	underplank	and apart from the the clj-http library is pretty damn good.
20:28	jeremyheiler	yeah, clj-http is a great lib
20:29	gfredericks	hyPiRion: it's because \Q...\E actually leaves alpha-ascii characters unchanged
20:29	gfredericks	it backslashes everything else
20:30	arrdem	why the hell...
20:30	hyPiRion	gfredericks: oh, so it's like a preprocessing step
20:30	gfredericks	hyPiRion: exactly
20:30	gfredericks	arrdem: because [a-zA-Z] normally have special meanings with a backslash but normal meanings without
20:30	gfredericks	with the exception of \p{...} that we were just playing with
20:30	gfredericks	I expect that's the only place where [a-zA-Z] have a special meaning and you can pull off that trick
20:31	gfredericks	&(re-matches #"\p{Al\Qph\Ea}+" "hello")
20:31	lazybot	⇒ "hello"
20:31	gfredericks	hyPiRion: it is a preprocessing step
20:32	gfredericks	it's right here in fact: https://github.com/openjdk-mirror/jdk/blob/2ea10c722507cde99026faa56068e2295bb93f11/src/share/classes/java/util/regex/Pattern.java#L1567-1619
21:11	ben_vulpes	what does ^Foo mean in the context of a (def ... ) form?
21:11	ben_vulpes	in particular, looking at https://github.com/michaelklishin/pantomime/blob/master/src/clojure/pantomime/mime.clj#L17 - is that some sort of type annotation perhaps?
21:12	gfredericks	yes, a type hint
21:12	ben_vulpes	thanks gfredericks.
21:12	justin_smith	,(meta (fn ^String [] "hi"))
21:13	clojurebot	nil
21:13	justin_smith	hrm...
21:13	gfredericks	ben_vulpes: it means e.g. that the call on line 33 can be figured out by the compiler
21:13	gfredericks	and doesn't have to use runtime reflection
21:13	justin_smith	gfredericks: it seems odd that the compiler couldn't infer that (Tika.) returns a Tika
21:14	gfredericks	justin_smith: it doesn't try very hard
21:14	justin_smith	yeah, I guess not
21:14	justin_smith	one k short of delicious
21:14	gfredericks	I assume the only inference it does is local
21:16	gfredericks	&(def justin_smith (Integer. 24))
21:16	lazybot	java.lang.SecurityException: You tripped the alarm! def is bad!
21:16	gfredericks	aw go away lazybot
21:26	ben_vulpes	https://github.com/michaelklishin/pantomime/blob/master/src/clojure/pantomime/mime.clj#L29 << regarding this protocol implementation, what sense does it make to extend the protocol for String, File, URL etc when in all of the implementations, everything is just run through a Tika (.detect Tika. input) call?
21:26	ben_vulpes	i ask out of ignorance, not arrogance :)
21:28	gfredericks	ben_vulpes: as opposed to just writing one function with that same implementation?
21:29	ben_vulpes	right.
21:29	ben_vulpes	that's the (naive, perhaps stupid) thing that i'd do.
21:29	gfredericks	it's the type hints again
21:29	gfredericks	at the jvm level I assume there are at least four different methods called "detect"
21:29	gfredericks	each with different type signatures
21:29	ben_vulpes	oho
21:30	gfredericks	and to avoid reflection you have to tell clojure (via type hints) which of those four you want to call
21:30	ben_vulpes	i think where i fail to grok is how the clojure type hint is conveyed to the jvm for the correct detect call
21:31	ben_vulpes	but -- outside of my scope atm. thanks, gfredericks!
21:31	gfredericks	np
21:54	justin_smith	ben_vulpes: I think it's more a question of if the clojure compiler can't tell when you compiler your code which class' method is to be called, it generates byte code that figures out the class, finds the method, and calls it
21:55	justin_smith	ben_vulpes: and that series of steps is why typehints make things faster
21:55	justin_smith	s/compiler/compile
22:35	ben_vulpes	makes sense, justin
22:35	ben_vulpes	justin_smith:
23:50	Lewix	can someone explain to me partial?
23:51	justin_smith	Lewix: it takes a function and N args, and returns a new function taking N fewer args
23:51	justin_smith	,(def +2 (partial + 2))
23:51	clojurebot	#error{:cause "First argument to def must be a Symbol", :via [{:type clojure.lang.Compiler$CompilerException, :message "java.lang.RuntimeException: First argument to def must be a Symbol, compiling:(NO_SOURCE_PATH:0:0)", :at [clojure.lang.Compiler analyzeSeq "Compiler.java" 6732]} {:type java.lang.RuntimeException, :message "First argument to def must be a Symbol", :at [clojure.lang.Util runtimeEx...
23:51	justin_smith	oops
23:52	justin_smith	,(def plus2 (partial + 2))
23:52	clojurebot	#'sandbox/plus2
23:52	justin_smith	,(plus2 2)
23:52	clojurebot	4
23:52	justin_smith	,(plus2 2 2)
23:52	clojurebot	6
23:53	Lewix	justin_smith: i fail to understand the purpose
23:53	Lewix	justin_smith: you could just create a function
23:53	justin_smith	Lewix: that's what partial is for
23:53	justin_smith	it creates functions
23:54	Lewix	.(defn plus2 [n] (+ 2 n))
23:54	justin_smith	Lewix: that would break for my second example
23:54	Lewix	i see. thns
23:54	justin_smith	the idea is it is simple to use, and will be exactly like the original function with some arguments pre-provided
23:55	justin_smith	see also comp
23:55	justin_smith	which also just creates a function, which you could use defn or fn to create
23:55	Lewix	justin_smith: thanks
23:55	justin_smith	but comp can be clearer sometimes
23:55	justin_smith	n
23:55	Lewix	I gotta fo
23:55	justin_smith	err, I mean np
23:55	Lewix	go*