#clojure – 2015-08-07

2015-08-07

00:28	batam	helloo,,,
02:56	hejki	ohai, how do I use literal '?' with jdbc queries? escaping does not seem to work, neither does using double ?.
03:05	ddellacosta	hejki: what are you using to connect to the DB? clojure.java.jdbc ?
03:05	hejki	clojure.java.jdbc yes
03:05	hejki	I am using PostgreSQL with jsonb-fields, and the syntax for checking json object key existence is: json_field_name ? 'keyname'
03:05	hejki	so I kinda need to pass the ? without appending any parameter values into it :P
03:06	hejki	with a quick glance the lib seems to have no support for "unprepared" statements and/or skipping parameter binding
03:07	ddellacosta	hejki: you should be able to do something like ["INSERT INTO foo (a, b) VALUES (?, ?)" "this" "that"] I believe
03:08	ddellacosta	passing that into execute
03:08	hejki	ddellacosta: yes, that works fine, what I cannot do is: ["SELECT COUNT(json_field ? 'somekey') FROM table"]
03:09	ddellacosta	oh sorry, I misunderstood--you want to pass the value '?' in?
03:09	hejki	ddellacosta: so what I want is to tell java.jdbc that the ? in the statement is literal ?, not placeholder for parameter
03:09	hejki	yes
03:09	ddellacosta	gotcha
03:09	hejki	maybe ["SELECT COUNT(json_field ? 'somekey') FROM table" "?"] works :D
03:10	hejki	... it does not :<
03:10	ddellacosta	huh, maybe! Dunno if prepared statements make sense with a select, but...
03:10	ddellacosta	ah
03:10	ddellacosta	one sec
03:12	ddellacosta	hejki: so, I just tried (j/query fdb ["SELECT E'?' as foo"]), and that worked
03:12	ddellacosta	gave me ({:foo "?"})
03:12	hejki	ahh! :)
03:12	ddellacosta	maybe that'll work for you, like COUNT(json_field E'?' 'somekey') ?
03:13	hejki	y, I am currently testing
03:13	hejki	nah... PSQLException ERROR: syntax error at or near "'exception'"
03:13	ddellacosta	hmm, one sec
03:13	ddellacosta	I think I have to be trying this on some json data to give you a useful answer
03:17	ddellacosta	damn, I need 9.4 for this don't I
03:17	hejki	y
03:17	hejki	:P
03:18	ddellacosta	alright, well, I don't care about that actually, if I get the same psql error w/c.j.j then it should work for you
03:20	ddellacosta	hmm, this appears to be a java issue actually
03:20	ddellacosta	specifically org.postgresql.core.v3.SimpleParameterList.checkAllParametersSet
03:20	ddellacosta	not that that helps you. :-p
03:20	hejki	hehe :P
03:21	hejki	I kinda guessed it is java issue :P
03:24	ddellacosta	testing out a more recent postgres jar
03:24	ddellacosta	this suggests it may be fixed already: http://postgresql.nabble.com/problem-with-pgjdbc-prepared-statements-and-new-jsonb-exists-operator-td5834634.html
03:27	hejki	hmm.. the mentioned version of postgresql lib is not available from clojars
03:28	ddellacosta	you can get it from maven
03:28	ddellacosta	w00t, that did it for me
03:28	hejki	1102 is available from clojars, that should be even newer, testing that no
03:28	hejki	now*
03:29	ddellacosta	(j/query fdb ["SELECT '[\"foo\", \"bar\", \"baz\"]'::jsonb ?? 'bar'"])
03:29	ddellacosta	PSQLException ERROR: type "jsonb" does not exist
03:29	ddellacosta	this is what I have in my project.clj for postgres: [org.postgresql/postgresql "9.4-1201-jdbc41"]
03:29	ddellacosta	that works
03:30	ddellacosta	anyways, hopefully that does what you need--good luck!
03:30	hejki	same version, still getting PSQLException No value specified for parameter 1.
03:30	ddellacosta	that's the same exception you were getting before?
03:31	hejki	yes, nvm my version was 1102 :P
03:31	hejki	testing the 1201
03:31	hejki	ahh
03:31	hejki	yes
03:31	hejki	!
03:31	hejki	\o/
03:31	hejki	it works
03:31	hejki	ty alot
03:31	ddellacosta	sweet!
03:31	ddellacosta	glad you got it working
03:31	hejki	yup, have to use double ? though
03:31	ddellacosta	yeah, may be stuck with that for now
03:32	hejki	that is actually tolerable imo
03:32	hejki	since it is quite special case
04:11	supersym	Is there a way (like in F#) that I can choose what data from a defrecord to output when printing? I am using one as a storage for blobs of text but it clutters my entire screen making it harden to sift through data
04:11	supersym	(just need to keep it to inspect the original texts when something goes wrong)
04:15	Kneiva	supersym: Like this? http://stackoverflow.com/a/3689364/1790621
04:17	supersym	Kneiva: exactly! Thanks for the reference
04:23	Kneiva	np
04:26	slhsen	Hey, anyone used https://github.com/hugoduncan/clj-ssh before? I got a question about it.
05:15	cmarques	Hi, I'm reading through https://github.com/technomancy/leiningen/wiki/Faster, which lists different ways of making leiningen boot faster. However, it's hard to know pros and cons of each strategy. What would be a good general strategy for faster boot time when using leiningen? Thanks!
05:30	kwladyka	i found interesting article about performance in Clojure, just sharing with you http://www.learningclojure.com/2013/02/clojure-is-fast-is-clojure-still-fast.html :)
05:40	jkogut_gs	kwladyka, eeee "Sorry, the page you were looking for in this blog does not exist. "
05:41	oddcully	not true
05:41	oddcully	loads for me at least
05:42	jkogut_gs	hmmm
05:43	kwladyka	it works for mee
05:43	kwladyka	:)
05:45	jkogut_gs	ok, few times refresh and works
06:24	kwladyka	haha i solved it!!! so many days of work and solve it! So happy, i am going rest :)
06:25	eaz4Ohfi	kwladyka: I have no idea what are you talking about, but congrats anyway :)
07:45	namra	ah strange things :/
07:46	namra	tests run fine, and manual http request via curl throws a cryptic exception :/
08:04	kungi	namra: cryptic?
10:30	hefesto	Good morning :) When I try to use the CIDER repl I get an "java.io.FileNotFoundException: Could not locate clj_antlr/core__init.class or clj_antlr/core.clj ..." error, but using the lein repl works fine. Does anyone know why?
10:40	chouser	hefesto: can you (require 'clj-antlr.core) in the lein repl?
10:40	hefesto	yes
10:41	hefesto	i even use a function from clj-antlr and it returns the expected
10:42	hefesto	chouser: and thank you for responding :)
10:45	chouser	hm, maybe paste your project.clj in a gist or something? Anything weird in your .lein/profiles.clj?
10:50	akabander	?
10:50	hefesto	chouser: I've never used gist. I hope i did it right: https://gist.github.com/hhefesto/0aa1a57bb6120b03ff16
10:50	expez	Has anyone written a lein plugin yet which converts a cljc based lib to an artifact containing only clj and cljs files? I'd like to use cljc, but I don't want to force consumers to use 1.7...
10:56	puredanger	that is effectively what cljx does
10:58	puredanger	or rather that takes a source template and spits out new source files. doesn't exactly solve this problem, just mean it has the right shape.
11:12	chouser	hefesto: Hm, looks pretty vanilla. I don't really have any explanation. Are there any other errors during cider-jack-in, prior to the FileNotFound?
11:15	hefesto	chouser: It magically got resolved. I'm sorry. I have no idea how. I just called cider-jack-in from project.clj rather than from my src file and it now works.
11:15	chouser	I think if someone needs to apologize, it's not you. :-) Glad it's working for you now.
11:16	hefesto	thank you so much anyway :)
11:17	chouser	np
12:12	{blake}	Is it fair to say "cons always returns a list"? I know there are different classes that might be returned, but they're all broadly "lists" (versus, say, vectors).
12:12	justin_smith	,(list? (cons :a nil))
12:12	clojurebot	true
12:13	justin_smith	,(list? (cons :a []))
12:13	clojurebot	false
12:13	justin_smith	,(type (cons :a []))
12:13	gfredericks	{blake}: if you relax "list" to "seq" then yes
12:13	clojurebot	clojure.lang.Cons
12:13	justin_smith	,(seq? (cons :a []))
12:13	clojurebot	true
12:14	justin_smith	it's casual friday for lists, they can relax today
12:14	{blake}	gfredericks: So, I guess the question is, is it wrong to do so? Even though it's pretty common to be casual about the word, it could trip you up.
12:15	{blake}	My "lists" are all in hawaiian shirts and shorts today.
12:18	gfredericks	{blake}: depends on the linguistic context
12:19	Ch3ck_	I'm kinda confused between learning Erlang and Clojure, can anyone just give me some opinions on why I clojure might be the future?
12:19	{blake}	gfredericks: Yeah. There's the other, sorta M. Night Shyamalan side of this: A ha! You never noticed that when I said "list" I meant actual lists, not sequences! That's not great eitehr.
12:21	justin_smith	Ch3ck_: if you want ultimate stability and rolling updates and highest possible availability, I'd go with erlang. If you want a modern language and number crunching speed while being good at concurrency, that would point to Clojure.
12:22	justin_smith	Ch3ck_: then of course there is syntax, ecosystem of libraries, etc. to consider
12:22	Ch3ck_	justin_smith, I like clojure because of it's intersection with Java and the JVM
12:22	justin_smith	yeah, that is a bonus - it's the real reason I can use Clojure at work
12:22	Ch3ck_	so was thinking it will help me some time in the future cover for Java's mistakes with JP
12:23	justin_smith	JP?
12:23	Ch3ck_	justin_smith, sorry FP
12:23	justin_smith	yeah, Clojure is good for that
12:23	Ch3ck_	justin_smith, any recommended books?
12:23	Ch3ck_	It's confusing looking at the list on stackoverflow ;)
12:24	Ch3ck_	A newbie might not know which one to choose
12:24	{blake}	Ch3ck_, justin_smith: Yeah, me, too. POI FTW!
12:24	justin_smith	the O'Reilly clojure book is good. Clojure From the Ground Up and Clojure For the Brave and True are free online
12:25	Ch3ck_	thanks justin_smith. {blake} any suggestions too?
12:25	justin_smith	Ch3ck_: if you already have a lispy background (eg. common lisp or scheme experience), Joy of Clojure is excellent
12:25	oddcully	clojure applied tackles real world problems. might be missing in "old lists"
12:25	Ch3ck_	I have no experience with FP.
12:25	Ch3ck_	Clojure will be my first
12:25	{blake}	Ch3ck_: I don't like the books, although I'm going through Living Clojure right now and hoping it will be better.
12:26	Ch3ck_	Aight, will check justin_smith's recommendations
12:26	justin_smith	Ch3ck_: tbh I learned more about clojure by lurking here and following the conversation than anywhere else
12:26	{blake}	At least for me, I'd start reading one of these things, and there'd be 20 pages up front on Clojure's amazing destructuring capabilities, or some really deep abstraction stuff.
12:26	gfredericks	{blake}: I think technical contexts will always be that way; we don't have nearly enough words for our concepts so we overload them everywhere, and the only way to be sure you're communicating effectively is to clarify a bunch
12:26	{blake}	I managed by alternating between here, 4clojure, the books, and writing code.
12:27	{blake}	gfredericks: Yes, there's some of that. But each language has its own frailties as far as it goes. Like, for Ruby, it's this gungho "Learn 15 DSLs 'cause Ruby is so easy and it all looks like English!"
12:27	Ch3ck_	Alright, guess. I'll be lurking here more often justin_smith {blake}
12:28	Ch3ck_	I don't know any programmer who codes in Clojure in my Country
12:28	justin_smith	{blake}: that reminded me of a great thing I heard today "familiarity will increase, but complexity is forever"
12:28	{blake}	I think FP's--and especially Clojure--"weakness" is that it's demanding. Algol-type languages are easy.
12:29	{blake}	justin_smith: Yes! Just so.
12:29	justin_smith	Ch3ck_: haha, actually one bonus of Clojure is there is very little syntax, so it can take a bit more effort to really do things obscurely (though we know a few tricks)
12:29	{blake}	And I think the problem with clojure books is that it's hard to remember what it was like to NOT be familiar with things.
12:29	xemdetia	I think it is also important for clojure to at least know some rudimentary things about Java- going into clojure blind without any java background will be painful
12:30	{blake}	(Which is a problem with all tech books written by experts, but doubly so for Clojure.)
12:30	Ch3ck_	I code in Java xemdetia
12:30	justin_smith	{blake}: yeah, writing intro books is hard because memories of what was difficult as a beginner are very unreliable
12:30	Ch3ck_	my GSoC project is in java
12:30	xemdetia	well then at least you understand what the JVM has under the hood that you can call out to
12:30	akabander	Actually I'm using Clojure so I don't have to learn Java (syntax). I don't mind learning about the JVM.
12:30	{blake}	xemdetia: Might be. I think any OO experience is enough.
12:30	justin_smith	xemdetia: eh, it wasn't very painful for me (though I had used other OO languages)
12:31	justin_smith	xemdetia: I think enough java knowledge to be able to read a javadoc is sufficient
12:31	{blake}	justin_smith: Yep. I think I'm pretty good at it, if I say so myself. =P
12:31	Ch3ck_	justin_smith, Yeah
12:31	xemdetia	justin_smith, yeah that's all I was indicating
12:36	gfredericks	justin_smith: good quote
12:41	tmtwd	http://pastebin.com/1GRW3gwX can someone help we figure out how this reagent code is supposed to work?
12:41	tmtwd	*me
12:42	Ch3ck_	tmtwd, have your tried paste.kde.org? it's cleaner
12:42	tmtwd	https://paste.kde.org/p5kjvkgxa ok here you go
12:43	oddcully	tmtwd: onchange gets an event object
12:43	tmtwd	there was another pastebin alt that was awesome but I can't remember what its called
12:43	oddcully	then the code there basically in JS would look like: event.target.value
12:43	tmtwd	so how would I hardcode in a value so it always changes to that value?
12:44	oddcully	#(reset value "lerl")
12:44	tmtwd	oh I see
12:45	BinaryResult_	Hey everyone, we are hiring remote full-stack clojure developers, hope to hear from you! http://discomelee.com/jobs/
12:45	tmtwd	#(reset! value @value) so why can't I just do that?
12:47	oddcully	you can do that. but thats a noop
12:47	gfredericks	mostly
12:47	gfredericks	there's a race condition there where it might undo something else
12:47	gfredericks	but otherwise it's a noop
12:49	oddcully	can it? in javascript?
12:49	oddcully	race i mean
12:49	tmtwd	oh I think I get it :)
12:50	gfredericks	oddcully: probably not then
12:55	sdegutis	Hi what's Clojure's version of the Haskell thing where you can use (< x) as a function?
12:56	gfredericks	#(< % x)
12:59	justin_smith	gfredericks: I think the retry behavior of atoms ensures that #(reset! % @%) is always a noop
12:59	justin_smith	gfredericks: retries man, I tell ya hwat
13:00	chouser	I don't think that's right. goes off to test
13:00	amalloy	justin_smith: no, it can undo something, like gfredericks says
13:01	gfredericks	justin_smith: no way man
13:01	gfredericks	justin_smith: it's (swap! a identity) that's always a noop
13:01	amalloy	if you time things wrong, then running (swap! a inc) and (reset! a @a) at the same time will result in a returning to its old value
13:01	justin_smith	oh, wait - does reset! do retries at all?
13:01	amalloy	no
13:01	justin_smith	aha, that was my mistake
13:01	amalloy	how could it? there's no computation to redo
13:02	justin_smith	d'oh, right
13:02	Bronsa	sdegutis: partial
13:04	sdegutis	Bronsa: partial can place unspecified arguments in arbitrary positions in a function call?
13:06	chouser	,(let [a (atom 0), f (future (loop [] (reset! a @a)))] (dotimes [_ 1000] (swap! a inc)) (future-cancel f) @a)
13:06	clojurebot	#error {\n :cause "no threads please"\n :via\n [{:type java.lang.SecurityException\n :message "no threads please"\n :at [clojurebot.sandbox$enable_security_manager$fn__857 invoke "sandbox.clj" 94]}]\n :trace\n [[clojurebot.sandbox$enable_security_manager$fn__857 invoke "sandbox.clj" 94]\n [clojurebot.sandbox.proxy$java.lang.SecurityManager$Door$f500ea40 checkAccess nil -1]\n [java.lang.Threa...
13:06	chouser	aww
13:07	chouser	&(let [a (atom 0), f (future (loop [] (reset! a @a)))] (dotimes [_ 1000] (swap! a inc)) (future-cancel f) @a)
13:07	lazybot	java.lang.SecurityException: You tripped the alarm! future-call is bad!
13:07	justin_smith	chouser: thanks for the example
13:07	gfredericks	sdegutis: there's no precise syntactic analog; you can write functions/macros to do whatever you want, but nothing will be as succinct as #(...)
13:07	chouser	Oh well. Guess you have to run it yourself. Anyway, if (reset! a @a) were noop then that would always return 1000
13:08	justin_smith	right
13:08	chouser	For me, generally returns something between 850 and 900
13:08	justin_smith	I forgot that reset! never retries
13:08	justin_smith	returned 840 here
13:09	chouser	I actually thought reset did retry like (swap! a (constantly x)), but the (current) code says no: https://github.com/clojure/clojure/blob/1d5237f9d7db0bc5f6e929330108d016ac7bf76c/src/jvm/clojure/lang/Atom.java#L97
13:11	justin_smith	chouser: https://www.refheap.com/107873
13:11	justin_smith	I'm actually surprised at how many times it got the right answer, considering
13:12	chouser	nicely done
13:15	justin_smith	chouser: now I'm confused - that loop doesn't recur, so how does it reduce the total by that much...
13:15	justin_smith	also the version with a recur doesn't return because future-cancel can't cancel it because it doesn't hit a cancellable operation (needs a sleep I guess)
13:15	sdegutis	gfredericks: So #(...) is the transliteration of Haskell's sections?
13:17	justin_smith	if I throw in a (Thread/sleep 1) it behaves exactly like the one without a call to recur
13:19	gfredericks	sdegutis: #() is more general; haskell's syntax only works on binary operators I believe, which isn't a syntactic concept clojure even has
13:20	sdegutis	gfredericks: I didn't know Haskell has "binary operators". I thought they were just ordinary functions that have special permission to be called using infix notation.
13:21	chouser	justin_smith: ha, missed the loop! So the damage is caused entirely by a single reset!
13:21	gfredericks	sdegutis: that's what I meant, they're syntactically special
13:21	gfredericks	that's all I'm using "operator" to mean
13:21	chouser	which explains why sometimes it actually gets all 1000 -- when the reset! doesn't actually fire until after the dotimes is complete
13:21	sdegutis	gfredericks: Oh Nice Thanks.
13:21	justin_smith	chouser: paste updated with proof https://www.refheap.com/107873
13:25	amalloy	gfredericks: i mean you can partially apply either the first or second arg of any function in haskell by making it temporarily infix: filter ((0 ==) . (`mod` 5)) [1..20] == [5,10,15,20]
13:25	chouser	(let [a (atom 0), stop (atom false), f (future (loop [] (when-not @stop (reset! a @a) (recur))))] (dotimes [_ 5000] (swap! a inc)) (reset! stop true) (Thread/sleep 100) [f @a])
13:25	amalloy	so it does only work on infix functions, but those functions can have any number of args, and you can make anything inline if you want
13:26	justin_smith	chouser: the future-cancel works in your original if you add (Thread/sleep 1), that's enough to make the loop cancellable
13:26	chouser	ah, nice
13:26	amalloy	justin_smith: (Thread/yield)
13:26	justin_smith	amalloy: oh, sweet
13:26	justin_smith	(inc amalloy)
13:26	lazybot	⇒ 289
13:27	amalloy	that's basically a (Thread/sleep 0) that doesn't waste time talking to the system clock or whatever
13:27	justin_smith	very cool
13:28	amalloy	this may be the first time in history anyone has called Thread/yield very cool
13:29	justin_smith	haha, I'm easily impressed
13:43	puredanger	(.join (Thread/currentThread)) ;; the sound of one thread deadlocking
13:53	chouser	heh
13:59	iamjarvo	so i am trying to get lein repl to use a newer version of nrepl right now it uses 0.2.6 from my understanding if i put [org.clojure/tools.nrepl "0.2.10"] in the dependencies in the project.clj it should use a newer version of nrepl but its not :(
14:02	justin_smith	iamjarvo: it's a magic thing where you need the plugin in profiles.clj iirc
14:02	justin_smith	not just the dep
14:03	justin_smith	the job of the plugin is to inject the dep
14:04	iamjarvo	justin_smith so i see this "Retrieving org/clojure/tools.nrepl/0.2.10/tools.nrepl-0.2.10.jar from central
14:04	iamjarvo	Retrieving org/clojure/clojure/1.2.0/clojure-1.2.0.jar from central" but then i see this when the repl starts "nREPL server started on port 55376 on host 127.0.0.1 - nrepl://127.0.0.1:55376
14:04	iamjarvo	REPL-y 0.3.5, nREPL 0.2.6"
14:04	justin_smith	iamjarvo: right, that's because it needs to do its thing as a plugin, it's conflicting with lein stuff
14:05	iamjarvo	justin_smith are you talking about the :plugins in project.clj?
14:05	justin_smith	iamjarvo: it has to be in profiles.clj, but yes, in plugins
14:06	justin_smith	profiles because that takes precedence
14:10	iamjarvo	justin_smith here is a pastie of my setup http://pastie.org/private/7zkcffxw4l8phzaaj9azw
14:10	justin_smith	iamjarvo: that's not a valid profiles.clj
14:11	iamjarvo	crap sorry i double pasted
14:11	justin_smith	haha, OK
14:12	iamjarvo	here is a fresh link http://pastie.org/private/942edrwxn1tb8sybor7v3a
14:13	kwladyka	justin_smith, i solved my problem! :)
14:13	justin_smith	iamjarvo: :plugins is being treated as a profile name
14:13	justin_smith	kwladyka: oh wow, what was the trick?
14:13	kwladyka	justin_smith, algorithm was slaw because of duck duck typing
14:13	kwladyka	justin_smith, i need to declare datatype
14:13	justin_smith	iamjarvo: the tools.nrepl plugin should go inside :user :plugins
14:13	iamjarvo	ahh because its in its own map
14:14	justin_smith	iamjarvo: right, also I don't think you meant to make a profile named :dependencies either :)
14:14	kwladyka	justin_smith, read this article, it is very interesting http://www.learningclojure.com/2013/02/clojure-is-fast-is-clojure-still-fast.html
14:15	justin_smith	kwladyka: someone should have mentioned turning on reflection warnings, I guess I'll remember that next time
14:15	kwladyka	justin_smith, all because of weak typing
14:16	kwladyka	justin_smith, turning on reflection warnings?
14:17	justin_smith	,(defn foo [x] (.length x))
14:17	clojurebot	#'sandbox/foo
14:17	justin_smith	,(set! warn-on-reflection true)
14:17	clojurebot	#error {\n :cause "Can't change/establish root binding of: warn-on-reflection with set"\n :via\n [{:type java.lang.IllegalStateException\n :message "Can't change/establish root binding of: warn-on-reflection with set"\n :at [clojure.lang.Var set "Var.java" 221]}]\n :trace\n [[clojure.lang.Var set "Var.java" 221]\n [sandbox$eval48 invokeStatic "NO_SOURCE_FILE" -1]\n [sandbox$eval48 invoke...
14:18	justin_smith	kwladyka: anyway, in a real repl you can use set! like above, and then if you run that defn it will tell you about the reflection
14:18	justin_smith	which is what makes the underspecified code so slow
14:19	justin_smith	kwladyka: so you can turn on warn-on-reflection at the top level of your project, and get warnings about the places where your code will be slow because the types are not known
14:19	iamjarvo	justin_smith in my endless changing and trying diff things created those maps. thanks for the second eyes
14:19	justin_smith	iamjarvo: np, hope that helps you solve the issue
14:20	kwladyka	justin_smith, so good to know
14:21	kwladyka	justin_smith, thx
14:21	kwladyka	i am so happy to found out why my algorithm is slow and i learnt a lot
14:22	kwladyka	i am also very surprise about time performance because of duck duck typing
14:44	sdegutis	Can anyone recommend any Clojure library that's simple yet powerful?
14:45	kwladyka	sdegutis, ?
14:45	chouser	clojure.zip ?
14:49	wasamasa	clojure.core
14:50	sdegutis	None of those show up in https://github.com/search?q=simple+powerful&l=Clojure
14:50	wasamasa	lol
14:50	sdegutis	I'm pretty sure you can use this as a metric of language popularity. 68 for Python, 75 for Ruby, 248 for JS
14:51	amalloy	is clojure.zip simple? the implementation isn't, and the api doesn't seem that simple either
14:53	pbx	as a clojure noob coming from python, i'm going to give a short "clojure is cool" talk to my python-using coworkers in an hour. any evangelism tips?
14:54	scriptor	try to use concrete examples
14:55	justin_smith	pbx: I'd stress the easy vs. simple thing - python is often easy, but the semantics are not simple, whereas clojure has simpler semantics
14:55	scriptor	tons of people have said "pure functions make code easier to reason about", it's more effective to show why that's the case
14:56	justin_smith	ahh yeah, a concrete example of where certain common bugs become impossible with immutable datastructures
14:56	scriptor	maybe brainstorm any bugs from your own company's codebase that might've been avoided or better handled with clojure
14:56	amalloy	pbx: how short?
14:57	amalloy	i have slides for a 40-minute "why clojure" presentation on Drive somewhere
14:57	scriptor	amalloy: I'd be interested in seeing that in general
14:57	pbx	amalloy, 10 minutes
14:58	amalloy	oh i guess i called it "a taste of clojure"
14:58	amalloy	https://drive.google.com/open?id=1mGihUBBIKMQn5Uz-5DvQ1Vu24qSuk3o4yUoPoBZW3tI
14:59	justin_smith	amalloy: that's a nice demo
14:59	Jaood	pbx: compare python's horrible lambda to clojure ;)
14:59	justin_smith	the third page
14:59	Jaood	ones
14:59	pbx	good stuff amalloy thanks
15:00	justin_smith	amalloy: btw, using Thread/yield instead of Thread/sleep led to me having to run a killall -9 java :(
15:00	amalloy	haha what
15:00	justin_smith	amalloy: the deal is, I was launching 10000 futures, and cancelling each one
15:01	justin_smith	this ran out of threads available, which fucked up nrepl - the client died, but the server was still running
15:01	justin_smith	it got to the point where I couldn't even start new nrepls after a few times (I was trying to figure out what was wrong)
15:02	justin_smith	because future-cancel can't kill a tight loop that is calling Thread/yield on my jvm apparently (though Thread/sleep 1 was killable by future-cancel)
15:02	amalloy	$javadoc Thread yield
15:02	lazybot	http://docs.oracle.com/javase/6/docs/api/java/lang/Thread.html#yield()
15:02	amalloy	oops
15:02	amalloy	okay so that doesn't ever get interrupted
15:03	justin_smith	amalloy: yeah, I don't think it's on the magical list of things that lead to cancellability
15:03	justin_smith	while waiting on input and sleeping are
15:03	amalloy	justin_smith: it's not so much a magical list of things, as anything that declares it can throw InterruptedException
15:03	justin_smith	ahh, interesting
15:03	justin_smith	very good to know
15:03	amalloy	because those are typically generated only when someone says "hey man, stop this thread, something is happening"
15:04	justin_smith	anyway, this is like the first time in over a year I have had to run killall -9 java, so congrats
15:04	justin_smith	lol
15:06	sdegutis	pbx: nope sorry.. the only things Clojure has over Python are destructuring and JVM libs
15:06	amalloy	haha
15:06	amalloy	justin_smith: (dorun (repeatedly #(future)))
15:07	amalloy	what could go wrong
15:07	sdegutis	pbx: and ->> makes map/filter/etc slightly nicer than Python just because Python's dumb and uses global functions unlike Ruby
15:08	sdegutis	This week's Annual Clojure Challenge! What's the most interesting and/or bizarre thing you can do with a Set?
15:08	sdegutis	aaaaaand... Begin!
15:41	dxlr8r	is it possible to "get" all params to a function (defn) to a list without manually assigning them? like "& args" but with named arguments
15:49	dxlr8r	(defn [a b c] (print (abc-coll)) :) like that
15:51	tmtwd	I'm trying to do string concat in cljs like this : http://pastebin.com/ab0n9KEh what is the best way to do that?
15:52	chouser	I think you can just leave out the ++'s
15:54	tmtwd	chouser, thanks :)
15:58	irctc	anyone here using domkm/silk on a webserver?
16:04	alex_engelberg	dxlr8r: you could try something like (defn [& [a b c :as all-args]] ...)
16:07	DomKM	irctc: Most users I've talked to use Silk for frontend routing. I think it works best when used on both the frontend and backend simultaneously. Happy to field questions. :)
16:08	irctc	DomKM: Thanks for responding - literally just opened up an issue with you on github.
16:09	irctc	I can explain here too though - I'm having trouble specifying request methods in my routes... I can show you code but that might be easier on github.
16:10	amalloy	dxlr8r: the only thing that doesn't involve retyping the arglist is what alex_engelberg is suggesting, but then you lose arity overloading, and arity checking: (foo 1) becomes legal now, setting [a b c] to [1 nil nil]
16:15	DomKM	irctc: Okay. I responded to the issue you opened.
16:57	{blake}	Does Clojure push a context on to the stack? (I'm asking because Smalltalk does but I haven't thought through if the same is necessary or useful in Clojure.)
17:01	amalloy	{blake}: the jvm uses the stack for locals, yes
17:02	{blake}	amalloy: Any non-user designated stuff? System info?
17:03	amalloy	well like, the return address and so on is there, i imagine
17:03	amalloy	but maybe not
17:03	{blake}	amalloy: OK, fair enough.
17:03	{blake}	(inc amalloy)
17:03	lazybot	⇒ 290
17:03	justin_smith	{blake}: as I understand it the jvm is relatively heap happy
17:03	amalloy	i was recently reading the jvm spec actually, and read the bit about stack frames
17:04	justin_smith	it's notorious for being more fragmented for that reason
17:04	amalloy	but i don't remember what is on there other than your locals
17:04	justin_smith	amalloy: what's on the stack will still be essentially a pointer to the actual object in the heap, right?
17:05	amalloy	yes, locals are always primitives or pointers to objects on the heap
17:05	{blake}	In Smalltalk, it's typically the sender, receiver, arguments, selector, locals and a home context.
17:06	amalloy	all of those are just locals on the jvm, except the sender doesn't exist and i don't know what a home context is
17:06	amalloy	oh or a selector
17:06	justin_smith	is a selector like a method?
17:06	justin_smith	no, that doesn't make sense
17:07	justin_smith	oh wait, it basically is - it's the method name essentially
17:07	amalloy	smalltalk has a much richer stack/environment than any language i know of
17:07	justin_smith	http://www.objs.com/x3h7/smalltalk.htm
17:07	{blake}	justin_smith: A selector is...a selector. =) Typically objects respond to the selector by calling a mathicng method. But they don't have to.
17:07	justin_smith	aha
17:07	{blake}	Yeah, it's one of the few languages I know where it's conceivable to debug with step-backwards.
17:09	{blake}	Seems like it could happen in Clojure, though.
17:09	justin_smith	{blake}: ocaml has a time-travel debugger
17:09	{blake}	justin_smith: Yeah! I'd heard that. I've only dabbled.
17:51	dxlr8r	alex_engelberg / amalloy: thx, but arity checking is kinda required
17:52	dxlr8r	I wrote some macro once to do it, but was to specific, guess I'm not good enough at them :)
18:12	kwladyka	is it possible to write functions like https://www.refheap.com/10aff5cf186a546b78d37dac6 with iterate or something like that?
18:31	justin_smith	kwladyka: that first one could be simpler as a reduce
18:33	justin_smith	(reduce (fn [new-boards board] (increment-board-by-piece board piece new-boards)) (empty boards) boards)
18:33	kwladyka	justin_smith, thx, i will see
18:33	justin_smith	second one is also simple to turn into a reduce
18:34	justin_smith	this general pattern (if you are taking rest on a list on each loop, and updating some value) is what reduce is for
18:35	awwaiid	justin_smith: I dug into ocaml's back-stepping debugger, and as far as I can tell it is actually a fork-based time travel technique. I ported the concept to ruby via pry-byebug. Really it is a unix trick more than anything though -- they are not running their bytecode interpreter backwards as I initially thought
18:36	justin_smith	oh!
18:36	awwaiid	exactly what I said :)
18:37	xemdetia	yes the simplest way to travel back in time is to have multiple times!
18:37	awwaiid	justin_smith: " set processcount count
18:38	awwaiid	Set the maximum number of checkpoints to count. More checkpoints facilitate going far back in time, but use more memory and create more Unix processes. " from http://caml.inria.fr/pub/docs/manual-ocaml/debugger.html
18:38	awwaiid	I think it does a combination of forking and replay
19:01	kwladyka	justin_smith, nice, even better performance and more readable :)
19:01	kwladyka	and... it is time to sleep, goodnight :)
19:08	noncom\|2	what is the best library for doing L-systems with clojure today?
19:24	sdegutis	What an exciting competition today! No submissions yet, which means everyone's working hard on something /really cool/!
19:25	sdegutis	For those just joining us: What's the most interesting and/or bizarre thing you can do with a Set?
19:25	sdegutis	First place gets first prize. Second place gets second prize. NOBODY ELSE GETS ANYTHING.
19:28	sdegutis	amalloy: richer how?
19:38	xeqi	sdegutis: i imagine it would be hard to surpass Russell's fun with sets
21:06	devn	Could anyone tell me how (defonce ^:const foo (assoc {:a 1} :b 2)) behaves under the covers?
21:06	devn	Is there anything I should be concerned about when using both defonce and :const metadata?
21:26	bcham	I'm getting something strange. I can't resolve "rename-keys".
21:26	bcham	http://pastebin.com/uX7JmH1w
21:26	bcham	select-keys works just fine
21:27	bcham	but rename keys doesn't, on clojure 1.6
21:27	bcham	What am I doing wrong oh wise men of #clojure.
21:27	bcham	and women*
21:28	bcham	well I figured it out, I had to drop down to clojure.set
21:28	bcham	because I'm stupid.
21:29	amalloy	devn: i think that would have the same effect as (defonce foo (...))
21:29	amalloy	or maybe something totally broken. at any rate it won't do what you wanted
21:32	devn	amalloy: so you think the :const metadata won't do anything?
21:33	amalloy	do you know what ^:const does?
21:52	gfredericks	amalloy: devn: I would definitely expect that ^:const changes things
21:53	gfredericks	defonce means that future calls to defonce are noops; ^:const means that when you use the var elsewhere in the code it compiles to a direct reference to the data, not to the var, so redefinitions aren't seen
21:53	gfredericks	afaik those two things are orthogonal
21:54	amalloy	gfredericks: i was imagining that the problem was in the actual implementation of defonce as a macro that expands to like (do (def ^:const x nil) (alter-var-root x (constantly whatever))
21:54	amalloy	but i think you are right that the value and the ^:const don't need to be set at the same time
21:55	gfredericks	,(source defonce)
21:55	clojurebot	Source not found\n
21:55	gfredericks	~defonce
21:55	clojurebot	defonce is a temptation
21:55	amalloy	~def defonce
21:56	gfredericks	~defonce is pronounced more or less like Beyoncé
21:56	clojurebot	c'est bon!
21:56	hiredman	I am amazed that ~def works
21:57	amalloy	hiredman: why?
22:02	hiredman	at one time it was a big pain, because the version of clojure clojurebot used to look up line numbers was way behind master
22:03	hiredman	which was back around 1.2 I think, and then I pulled the evaluator bit out of the process so it is easy to jump to new clojure versions and I haven't thought about it since
22:08	amalloy	well it's still linking to a really old version of core.clj
22:09	amalloy	~def do!
22:09	amalloy	,do!
22:09	clojurebot	#error {\n :cause "Unable to resolve symbol: do! in this context"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.RuntimeException: Unable to resolve symbol: do! 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: do! in this conte...
22:09	amalloy	isn't that a thing in 1.7?
22:10	amalloy	oh, it's run!
22:10	amalloy	,run!
22:10	clojurebot	#object[clojure.core$run_BANG_ 0x567f2d92 "clojure.core$run_BANG_@567f2d92"]
22:10	amalloy	~def run!
22:10	hiredman	huh, so the line number for defonce just happens to be the same
22:11	amalloy	hiredman: no, it's using the old version of clojure to look up a line number, and then linking to the corresponding line in an old blob on github'
22:11	amalloy	which is why ~def run! doesn't work
22:11	hiredman	Oh, right, didn't you have a pr for that?
22:11	amalloy	not me
22:11	hiredman	hmmm
22:13	hiredman	and the code lookup stuff is in the main clojurebot process, I was thinking I might fix it to lookup via the evaluator service, but forget it if it involves restarting anything