#clojure – 2015-08-31

2015-08-31

00:00	TEttinger	there's a lazy-cat?
00:00	justin_smith	TEttinger: have you ever seen a cat that wasn't lazy?
00:00	justin_smith	:P
00:00	justin_smith	(doc lazy-cat)
00:00	clojurebot	"([& colls]); Expands to code which yields a lazy sequence of the concatenation of the supplied colls. Each coll expr is not evaluated until it is needed. (lazy-cat xs ys zs) === (concat (lazy-seq xs) (lazy-seq ys) (lazy-seq zs))"
00:00	TEttinger	I mean, yes. I have a cat who was raised by dogs and thinks he is a dog
00:01	TEttinger	(plays with water, completely unafraid of almost everything, greets strangers instead of running like any other cat)
00:01	TEttinger	(doc reductions)
00:01	clojurebot	"([f coll] [f init coll]); Returns a lazy seq of the intermediate values of the reduction (as per reduce) of coll by f, starting with init."
00:03	joness2	i am not sure how lazy-cat works.. is it a macro that prevents strict evaluation?
00:03	justin_smith	joness2: exactly - all laziness in clojure requires function indirection or macros that prevent evaluation
00:03	justin_smith	if you dig down deep enough at least
00:04	Bronsa	oh well
00:04	Bronsa	looks like direct linking is broken
00:04	justin_smith	?
00:04	TEttinger	Bronsa: a grimoire thing?
00:04	Bronsa	http://dev.clojure.org/jira/browse/CLJ-1809
00:04	Bronsa	TEttinger wat
00:05	Bronsa	TEttinger no idea why you thought of grimoire but it's about a new 1.8 feature
00:05	TEttinger	oh, sorry, I just saw "direct linking" and couldn't remember if you did grimoire or who else did
00:05	Bronsa	I think I understand what's going wrong but it's a mess :/
00:06	Bronsa	TEttinger ah, no that's arrdem
00:06	TEttinger	brrnem
00:08	TEttinger	Bronsa: when's 1.8 scheduled, is it on some sort of fast track relative to 1.6-1.7?
00:08	Bronsa	TEttinger I seem to understand so, you'll have to ask puredanger
00:08	Bronsa	I'm a mere contributor, not part of the core team that make such decisions :)
00:09	TEttinger	I don't really know what the new features are. If I had to guess, monaducers
00:09	TEttinger	"because monads and transducers are so hot right now"
00:10	TEttinger	is clojure in clojure off the target list?
00:10	Bronsa	TEttinger cinc has never been an official target
00:11	TEttinger	err, maybe target is wrong word, goal to work toward?
00:12	Bronsa	no official plans, just unofficial efforts
00:12	TEttinger	ah ok
00:12	Bronsa	(mine :P)
01:00	H4ns	what self-hosted CI tool do you recommend for clojure? i've been using jenkins, but it is so ugly. teamcity does not seem to offer anything specific to clojure, but it looks slightly better. anything else?
01:01	justin_smith	I've only used jenkins, it worked OK
02:07	Jaood	´œ∑´®†\üø¨ˆπåß∂∂ƒ©©˙∆˚¬…ææ
02:07	Empperi	exactly that
02:07	Empperi	I agree 100%
02:08	Empperi	H4ns: we use Jenkins and it's fine as long as you don't need full deploy pipeline management
02:08	Empperi	it can do that too but it's hairy
02:09	Empperi	planning to move into Go CD
02:21	H4ns	thanks, justin_smith and Empperi - i guess we'll just put up with the ugliness and continue using jenkins. it works well for us, too.
04:50	Rancid-punk	2j Hi guys
04:50	Rancid-punk	Who is this man ? http://s22.postimg.org/cv0461qsh/Ratzinger_vreu7o.jpg
04:51	Bronsa	Rancid-punk: trolling is not welcome in this channel
06:58	Olajyd	Hi clojurians :)
07:01	Olajyd	I’m having a little issue with using the clj-time, I tried using the t/after and t/before to check if a particular date falls within the range, but I’m getting this error: `No such var: clj-time.core/equal?` even after requiring the clj-time 0.11.0 in the project.clj. Any ideas?
07:01	Olajyd	:)
07:08	oddcully	Olajyd: it might help, if you could provide a minimal failing example in a gist/refheap/...
07:08	Olajyd	ok
07:09	Olajyd	in a min
07:13	Olajyd	oddcully: https://www.refheap.com/109013
07:15	Olajyd	Alias for clj-time.core is `t` and alias for clj-time.format is `tf`
07:22	oddcully	Olajyd: without trying anything, the first two things: a) why do you not use t/equals? (most likely not related to the error) and b) equal? was added in 0.10.0
07:28	Olajyd	ok
07:28	Olajyd	odccully , got it now, bumped the version to 0.10.0 and it worked
07:29	Olajyd	was previously 0.9.0
08:20	noncom	is there any library that can generate a webform for a clojure map that is required to be filled?
08:20	wink	sounds like an ace idea :P
08:21	noncom	heh :)
08:30	oddcully	(map #(str "<input type=text name=" % "/>") (keys themap))
08:37	noncom	oddcully: nice start that would be! :)
08:42	neurostorm	lein repl does not seem to find my resources/log4j.xml file. several warnings are issued. should anything be added in the project.clj file except the dependency?
08:43	oddcully	noncom: since this is a little splitted between here and #clojurescript. above is not ordered
08:44	noncom	neurostorm: lein resource-paths? https://github.com/technomancy/leiningen/blob/master/sample.project.clj#L160
08:45	noncom	neurostorm: this level is better for you, i think: https://github.com/technomancy/leiningen/blob/master/sample.project.clj#L281 (or maybe not)
08:48	neurostorm	thanks!
08:58	neurostorm	(.exists (clojure.java.io/file (clojure.java.io/resource "log4j.xml"))) ; reports true, but still i get:
08:58	neurostorm	log4j:WARN No appenders could be found for logger (io.netty.util.internal.logging.InternalLoggerFactory).
08:58	neurostorm	log4j:WARN Please initialize the log4j system properly.
08:58	neurostorm	log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
09:01	neurostorm	ok, seems to be a error in the xml. sorry
09:03	crazydiamond	Hi. If I need to have map with like 10 mln keys, would be in-memory Datomic DB more performant than just Clojure map?
09:07	crazydiamond	Just got java.lang.OutOfMemoryError: GC overhead limit exceeded O_o
09:11	cenzhe	hi guys
09:11	cenzhe	what is the most effective way to keep a thread-safe count
09:12	cenzhe	my attempt now is: (def a-cache (atom {}))
09:12	cenzhe	(def inc-base-0 (fnil inc 0))
09:12	cenzhe	(defn record-one [n] (swap! a-cache update n inc-base-0))
09:14	cenzhe	but the performance is not satisfactory. I got the code embeded in my program, takes an extra 2 seconds to complete, and this routine get called around 550k times
09:15	cenzhe	I guess I need to avoid the boxing and unboxing of the count? like how?
09:16	expez	cenzhe: perhaps keep the count with an agent
09:16	cenzhe	cool idea
09:16	cenzhe	I'll add that in
09:17	cenzhe	anything else?
09:17	noncom	cenzhe: also, for things you need to do really fast, it is possible to use some direct java code. like you could have your counters written in java
09:17	noncom	as for the agent - i am not sure. agents are not guaranteed to be synchronized. of course in this case the count addition task likely won't take long, but you're walking thin ice..
09:18	cenzhe	noncom: I believe clojure can do things just as fast as Java with careful coding and proper optimization techniques
09:18	cenzhe	Me wrong?
09:18	noncom	cenzhe: another option would be to restructure your code. perhaps having a global count variable is not what you really need here. so, it will depend
09:19	noncom	cenzhe: in most cases, yes. but sometimes it is worth to write some 10 lines of java and be as fast as possible than have unstable or ugly clojure code that only tries to approach the same speed
09:21	noncom	cenzhe: as per your mentioned "proper optimization and careful coding" - i was referring it when i said that probably you could restructure your program to avoid the global counter
09:21	cenzhe	I don't quite follow the "global counter" part
09:21	cenzhe	noncom: what are the other alternatives?
09:22	noncom	cenzhe: you're keeping a counter, am i not right? here's your original question: "what is the most effective way to keep a thread-safe count?"
09:22	cenzhe	yes, actually a handful of counters
09:22	noncom	cenzhe: an alternative would be to include then in a (let ...) of a higher function
09:22	noncom	i cannot say more since i am not fully aware of your scenario
09:23	cenzhe	noncom: I guess this is to avoid the var deref cost, right?
09:23	noncom	right
09:23	noncom	but i am not sure it is applicable to your scenario
09:24	noncom	if you call the function on an external stimuli, like a key press, then you have to keep something global so the state can persist across the key presses
09:24	cenzhe	that seems to be possible, but I haven't tried this before, not sure how much boost I'll get
09:24	noncom	so, 1) java code, 2) include in a let of a higher function 3) use an atom.
09:25	noncom	if i'd care for speed, id use 1 :D
09:25	cenzhe	:D thanks for the leads
09:26	cenzhe	I just realize that my CPU are mostly occupied, the agent method may not work actually
09:26	cenzhe	I'll try the let first, and see how far that goes
09:46	noncom	crazydiamond: that's too much. although you could tweak JVM to get that heap... bu
09:46	noncom	you said 10 mln objects, you really need a db
09:46	noncom	coz
09:46	crazydiamond	noncom, yep, I realized that. thanks
09:47	crazydiamond	Hi all. How do I sent Clojure vec like ["foo", "bar"} via Clojure JNA to C function that excepts char** ?
09:47	sdegutis	I'm writing a blog post on mutability in Clojure's core, and I thought a sanity check would be prudent. Is there anything wrong with my conclusion, that Clojure inherently (and unidiomatically) relies on mutability for making defmulti/defmethod work?
09:48	spacepluk	sdegutis: I think all vars are mutable
09:50	sdegutis	But typically the community's agreed-upon idiomatic style is to write a var declaratively and pull it into the namespace that requires it.
09:51	sdegutis	In this case, the namespace defining the defmulti would then be required to :require the namespaces that have the defmethods.
09:51	sdegutis	Except that severely limits the "extensibility" of defmethod itself, since the creator of this "interface" is then required to know all the implementors.
09:52	sdegutis	So the only way to keep that extensibility is to force the implementation of these two methods to rely on mutating the defmulti whenever it comes across a defmethod.
09:57	spacepluk	sdegutis: why do you need to require the implementors namespace? :?
09:58	sdegutis	spacepluk: If you write a defmulti, and a defmethod in another namespace, but never require that namespace, then calling the defmulti with the dispatch-value used in that namespace will result in a no-matching-whatever error.
09:58	spacepluk	I mean the side exetending the multimethod requires the multimethod, I think that's ok
09:58	spacepluk	I see
09:59	spacepluk	but in a real usecase you'd be using the extender namespace I think
09:59	spacepluk	s/using/requiring/
10:01	spacepluk	I'm still learing clojure though, I might be missing something
10:01	spacepluk	n
10:01	sdegutis	We had a bug in our system a few years ago because we were using a web framework that required the namespace needed based on the request being made, so sometimes the ns with the extender wasn't required for quite a long time. It caused a lot of bugs that took us a while to figure out.
10:02	spacepluk	yeah, extending types is a lot like monkey-patching
10:02	spacepluk	it's probably not a good idea to do it dynamically at runtime
10:02	sdegutis	That's what I'm saying though, all extending of types currently happens at runtime.
10:03	spacepluk	yup
10:03	sdegutis	The problem only happens when you try to require namespaces at runtime instead of inside (ns (:require ...)).
10:03	spacepluk	with runtime I mean after the app starts
10:03	sdegutis	Ah right.
10:04	spacepluk	these are the "cons" of dynamic languages I guess :)
10:06	zetlen	hey folks. is it frowned upon to try and ask questions in #clojure-beginners and here at the same time?
10:11	sdegutis	go for it
10:20	sdegutis	Dear Emacs users in here: what Clojure packages do you use?
10:38	troydm	can anyone suggest core.logic tutorial?
10:48	ryuo	i have been considering the merits of various Lisp dialects. is there some reason to prefer closure to others such as common lisp or scheme?
10:50	blkcat	jvm integration would seem like a pretty major one
10:51	opqdonut	I love the persistent built-in data structures
10:51	opqdonut	and the parallelism and concurrency stuff
10:51	ryuo	by persistent, you mean how some Lisp implementations can save machine state to be reloaded later?
10:52	opqdonut	no
10:52	opqdonut	I mean that the structures are immutable (but efficient)
10:52	opqdonut	e.g. adding an element to the end of a vector gives you a new vector
10:53	opqdonut	means you don't need to worry about leaking references to your private structures, or insert deep copies everywhere
10:53	spacepluk	yeah, I really like that too
10:53	spacepluk	and jvm/js interop is a big plus
10:54	spacepluk	I also like the syntax sugar for the different data structures
10:54	spacepluk	hardcore lispers would disagree I guess
10:55	ryuo	i come from the world of low level C. i've been trying to break into functional, but Lisp is somewhat confusing to navigate in terms of where I expend my efforts.
10:55	ryuo	I should*
10:56	opqdonut	yeah it's not easy
10:56	spacepluk	if you're trying to interop with c code gambit or chicken might be better for you
10:56	spacepluk	there's clojure-terra but it's not finished
10:56	opqdonut	for getting stuff done you could look at clojure, but if you don't need the jvm or want to learn an "authentic" lisp go for some scheme variant
10:57	ryuo	Hm.
10:58	opqdonut	but it doesn't really matter, it's easy to transition from clojure to scheme or vice versa
10:59	opqdonut	just do something and see what happens
11:00	spacepluk	yup, switching from low-level to a functional style is the hard thing to do
11:02	spacepluk	maybe lua might help there, it's pretty much scheme with syntax
11:03	ryuo	i was thinking it wouldn't be too bad, considering i have a talent for abstract math...
11:04	ryuo	hm.
11:05	spacepluk	it's not too bad, just try to make something :)
11:06	ryuo	C did teach me that it is important to know a great deal about language nuances.
11:07	ryuo	if you want to use it to do a lot of programming at least.
11:07	spacepluk	the good thing about lisps is that the language itself doesn't have a lot of nuances, it's as simple as it gets.
11:08	ryuo	the rest is grasping the sheer flexibility you have?
11:08	spacepluk	yes hehehe
11:08	spacepluk	do you have any specific needs? or is it just for learning?
11:08	ryuo	well, i was wanting to learn a higher level language of the Lisp family to use for developing a MUD server's content.
11:09	ryuo	i was thinking C is a poor choice here due to the higher development costs.
11:10	ryuo	it takes longer to make anything useful with C. you have to implement a lot of support code before you get to the real content.
11:10	spacepluk	clojure sounds like a good fit for that
11:12	ryuo	is it still possible to draw from C libraries? i was planning to at least use C libraries to handle networking, unless java has some telnet lib.
11:12	spacepluk	I'm sure there are some
11:12	spacepluk	you can use JNI or JNA for the c code but it's not fun
11:14	spacepluk	or maybe this -> https://github.com/bagucode/clj-native
11:14	ryuo	okay, then is there some recommended reading for a through introduction to clojure? oreilly has a number of books but
11:14	ryuo	thorough*
11:14	ryuo	some appear to be for advanced topics in clojure.
11:15	ryuo	i still plan to write C code, but i need to also learn to use higher level languages.
11:15	ryuo	i can't limit myself to only low level. that's how i feel.
11:16	spacepluk	I read these: http://www.braveclojure.com/ https://www.manning.com/books/the-joy-of-clojure-second-edition
11:17	spacepluk	I think you might like lua, it's very easy to interact with c code and you can write functional code with it
11:17	ryuo	one other question. how stable is clojure for API? i'm used to C where APIs typically remain the same indefinitely.
11:17	spacepluk	specially luajit's ffi is great
11:17	spacepluk	I think clojure itself is pretty stable
11:17	ryuo	at least for ISO and POSIX.
11:17	ZimaBlue`	ryuo: I wouldn't recommend Joy Of Clojure, I read that already knowing bits about FP and found it way too hard. Probably the hardest textbook I've ever read. braveclojure is a good intro and currently enjoying "clojure programming"
11:19	ryuo	ZimaBlue`, I assume you had experience with non-FP before?
11:19	ryuo	i've used C for the last 7 years and enjoyed it, but i need something more.
11:19	ryuo	shell scripts only go so far as well.
11:20	ryuo	hm.
11:21	luxbock	ryuo, you could also look at Racket
11:21	luxbock	I haven't really used it much, but my impression is that it has an easier FFI support than Clojure
11:22	ryuo	so many Lisp implementations. -head explodes-
11:22	ryuo	haha
11:22	spacepluk	heheh
11:22	spacepluk	ryuo: you can also go this way http://www.buildyourownlisp.com/ :D
11:22	luxbock	John Carmack is using Racket to script his VR work
11:22	ryuo	maybe it would be best if i just studied what Lisps have in common.
11:23	ryuo	for now. i wonder if there is a book for that. =p
11:23	ZimaBlue`	the original paper by mcarthy
11:23	ZimaBlue`	called something like recursive functions of symbolic expressions
11:23	ZimaBlue`	http://www-formal.stanford.edu/jmc/recursive.pdf
11:24	luxbock	also, Structure and Intepretation of Computer Programs, which uses Scheme (which Racket is a dialect of)
11:25	ryuo	ah.
11:25	ZimaBlue`	it's pretty readable, I think I read that the compiler code in it has a couple of issues but you get the idea. Also halfway through he gets bored and invents GC
11:25	spacepluk	I think you'll learn more effectively if you can apply the stuff to real projects you're working on, that's what made it for me with lua/js
11:25	spacepluk	you see the benefits immediately
11:26	ryuo	that's the funny thing. it took me years of writing stupid things before I was good enough with C to do anything productive.
11:26	ryuo	I was used to high level doing so much implicitly.
11:26	ryuo	haha
11:26	luxbock	I have also heard many people praise this book http://www.ccs.neu.edu/home/matthias/HtDP2e/
11:27	luxbock	but I haven't read it myself, it's on the TODO list :)
11:27	spacepluk	little schemer is also very cool
11:27	spacepluk	and it's an easy read
11:27	luxbock	yeah, very funny as well
11:27	ryuo	the best application i've found for C was optimizing tasks that i couldn't find another way to speed up.
11:28	spacepluk	c is good for using c libraries hehe
11:28	spacepluk	are you familiar with oop?
11:29	ryuo	vaguely. mainly the general ideas i had to apply in a C context.
11:29	ryuo	a structure plus common functions.
11:29	noncom	how can i create a routing table for compojure so that it gets re-resolved on each http access to my server? ideally i'd like to store everything in a {} that i can update from time to time
11:29	spacepluk	good, don't waste your time :P
11:29	ryuo	that's about all it is in C.
11:29	tdammers	C is kind of cleansing
11:30	tdammers	useful for the rare occasions where you need a lot of control, at the expense of safety
11:30	ryuo	spacepluk, waste my time in C?
11:30	spacepluk	OOP
11:30	ryuo	yet it is what is so wildly advocated.
11:30	ryuo	all they talk about is OOP in my college courses.
11:31	ryuo	lol
11:31	tdammers	OOP is a local optimum
11:31	spacepluk	most people don't understand oop though
11:31	hfaafb	no true OOP
11:31	tdammers	and frankly, the original Kay OOP isn't such a bad idea at all
11:31	luxbock	I recently read http://arcanesentiment.blogspot.sg/2013/09/why-concatenative-programming-matters.html which makes me want to give Factor a try
11:32	ryuo	there's so many paradigms.
11:32	luxbock	there's tons of great posts in that blog
11:32	tdammers	but ironically, one of the languages that most closely does that isn't considered OOP at all, but "functional"
11:32	ryuo	even array programming. XD
11:32	spacepluk	tdammers: agreed
11:32	TMA	ryuo: OOP is easily explained to a pointy haired boss (on the level: see you have a car that has four wheels; let call each piece an object)
11:32	tdammers	yeah
11:32	tdammers	OOP looks familiar to management types
11:33	luxbock	oh whops, I meant to link http://evincarofautumn.blogspot.com/2012/02/why-concatenative-programming-matters.html
11:33	spacepluk	most people think that OOP is about shoehorning design patterns in your code and overengineering until you have to thow away the whole thing
11:34	spacepluk	at least that's my perception of it, with the people I've worked with
11:34	hfaafb	that's not what people think OOP is, that's what people experienced in big legacy monolithic repos
11:34	ryuo	huh. it talks about composition vs application.
11:34	hfaafb	like the ... eventual outcome of large oop systems
11:34	ryuo	what's the difference? at some point it has to executed...
11:34	tdammers	spacepluk: consider yourself lucky... it means that the people you've worked with are at least semi-enlightened
11:34	spacepluk	hehehe
11:35	spacepluk	fuck that's depressing
11:35	ryuo	i always thought composition was just combining functions to form a new kind of function
11:35	tdammers	ryuo: the difference isn't about how it gets executed; it's about how you keep your code manageable
11:35	luxbock	ryuo: yeah that whole explanation he gives for it is what really made me appreciate the post
11:35	tdammers	oh wait, different discussion
11:35	crazydiamond	Hi. How do I install library like this to use from Clojure? https://github.com/dren-dk/HunspellJNA I've installed it by "mvn install" but (import 'dk.dren.hunspell.Hunspell) raises java.lang.ClassNotFoundException
11:38	luxbock	crazydiamond are you using Leiningen?
11:38	crazydiamond	luxbock, boot
11:38	crazydiamond	luxbock, it's like leiningen in terms of :dependencies etc
11:39	spacepluk	crazydiamond: is it running with the correct classpath?
11:40	crazydiamond	spacepluk, at least I have access to other libs from ~/.m2 , like datomic
11:41	spacepluk	crazydiamond: are the native binaries included in the jar? :?
11:41	crazydiamond	dunno, but I have some in my system :)
11:41	spacepluk	I don't really know how that works, just shooting ideas
11:42	crazydiamond	it passed tests
11:42	crazydiamond	during mvn install
11:42	crazydiamond	spacepluk, it seems quite hard to get it working :-(
11:42	spacepluk	it looks like the bundle the binaries in a different jar, maybe it's a separate dependency?
11:42	crazydiamond	ah, you mean Java binaries
11:43	crazydiamond	not C
11:43	spacepluk	no the native binaries
11:43	crazydiamond	(it's the lib that gives access to C lib via JNA)
11:43	spacepluk	I think they put them in a jar
11:44	spacepluk	check for hunspell-linux* hunspell-win* etc.
11:44	spacepluk	maybe they are in a separate maven package
11:47	lambda-smith	Man, Clojure is so nice, I couldn't stop using it
11:47	crazydiamond	spacepluk, I've just added to :dependencies in my build.boot, and it works
11:48	spacepluk	ah cool, then it was the classpath
11:49	sdegutis	What's your usual technique on having a test-service (e.g. for email) and replacing it with a live-service (e.g. AWS-SES) when your program is live?
11:50	spacepluk	reader conditionals? :?
11:50	spacepluk	I have no usual technique though since I'm a noob hehe
11:51	sdegutis	Hmm I wonder... I bet the people who normally could answer this have me on /ignore
11:52	spacepluk	hehehe
11:53	sdegutis	Hi justin_smith.
11:59	justin_smith	sdegutis: hello
11:59	sdegutis	You must be really productive at work today justin_smith.
11:59	justin_smith	just getting started
12:02	spacepluk	is there any async alternative to monger?
12:02	justin_smith	doesn't monger support fire and forget? I thought that was the default with mongo stuff.
12:03	justin_smith	or do you mean like queries with callbacks
12:03	spacepluk	I don't know, it looks like it blocks the current thread
12:03	spacepluk	because it returns the result of the queries
12:03	spacepluk	yes
12:05	sdegutis	spacepluk: The nature of Mongo is that all queries block the entire Mongo server, in order to ensure consistent results.
12:06	sdegutis	We moved to Datomic in large part for that reason.
12:06	spacepluk	that doesn't mean that you need to block the client though
12:06	sdegutis	Datomic Free is working amazingly for us.
12:06	spacepluk	I really want to try that
12:09	spacepluk	but for this I need mongodb :/
12:11	spacepluk	I guess I can just use the java driver but monger looked so good :(
12:11	justin_smith	spacepluk: you could use (future (callback (monger/query ....)))
12:11	justin_smith	unless the java driver does something nicer I guess
12:12	justin_smith	also what about using monger and then using the java driver directly for the features monger doesn't support?
12:12	spacepluk	will that spawn a thread for every query? I'm still learing clojure's in and outs
12:12	spacepluk	that's a good idea
12:13	justin_smith	spacepluk: each call to future uses a thread from the thread pool
12:13	justin_smith	the thread gets returned to the pool when the callback returns
12:13	spacepluk	the limits the number of concurrent queries, right?
12:13	spacepluk	s/the/that/
12:13	justin_smith	the thread pool is unlimited
12:13	justin_smith	well, limited by what your OS can do thread wise I guess
12:13	spacepluk	that sounds scary hehehe
12:14	justin_smith	you can also use core.async or your own thread pool if you want something more controlled
12:14	justin_smith	you could mitigate this by putting one callback on a series of queries all in one future
12:14	justin_smith	or by making a thread pool doing queries where you specify the max size
12:15	noncom	does anyone know how to get data from backend into a reagent form ?
12:15	noncom	i want the page to be generated with data from the backend... is this possible at all?
12:15	justin_smith	noncom: I typically use a websocket
12:15	noncom	justin_smith: can you give a tiny code example?
12:16	justin_smith	noncom: or you can have a backend service that serves up your form I guess
12:16	justin_smith	noncom: websockets and tiny examples don't really go together so nicely...
12:16	noncom	oh ok
12:16	spacepluk	justin_smith: thank you, that's very helpful :)
12:16	justin_smith	unless you were planning on a websocket architecture, what about a service on your backend that returns your base form for reagent as json?
12:16	noncom	i'm just trying to get some real data into html forms generated in luminus, which uses reagent on this
12:17	justin_smith	OK
12:17	justin_smith	well, you could make luminus put real data in there right?
12:17	noncom	no
12:17	justin_smith	is it really that inflexible?
12:17	noncom	i think i'm missing something, that's what. i can't believe it is that inflexible
12:18	noncom	yes, a backend service that returns forms is how i always did it in the past
12:18	justin_smith	noncom: eg. I'd think you could make a function that takes a template, fills in some parts of it, and returns a new template for the frontend reagent to use
12:18	noncom	but you see, luminus has new features now so i am tryin to explore them
12:18	justin_smith	noncom: or you could have a ajax/json service that gives the data to reagent...
12:19	sdegutis	justin_smith: how do you select between services (e.g. an email-service) depending on your environment, so that you get an in-memory service when running tests or running a dev environment, and a live one in production?
12:19	justin_smith	noncom: OK, best of luck
12:19	noncom	justin_smith: yeah.. i just don't know how to organize data transfer between my clj and cljs code..
12:19	noncom	eh, this is all too much.. i have to figure out many things before i get there.. or just use the old approach - simply make the backend generate the forms
12:20	justin_smith	sdegutis: I use environ usually - my latest madness is to have a "config" component that sets up all this environment specific stuff (or at least populates an options map so my other components can be configured)
12:20	sdegutis	by component do you mean stuartsierra/component ?
12:20	justin_smith	noncom: I think the json/ajax approach is straightforward enough - reagent makes ajax request, gets json data, fills in data used for rendering, renders page
12:21	justin_smith	sdegutis: indeed
12:21	noncom	yes. now i just have to find out how to add ajax request and data display to reagent templates..
12:21	justin_smith	noncom: reagent should already be taking data from memory (an ratom right?) and using that to render
12:21	sdegutis	Hmm everyone seems to be using Component these days.
12:22	justin_smith	noncom: the only extra step is making an ajax request and putting data from the result into your ratom(s)
12:22	sdegutis	I built my app before the days of Component so I don't really know how I'd restructure it to fit that in hree.
12:22	sdegutis	*here
12:22	justin_smith	sdegutis: using environ to select your config map from a map of maps should work with or without component, component just makes the whole thing cleaner
12:23	noncom	justin_smith: you mean that reagents atom incapsulates ajax interaction?
12:23	sdegutis	Right, I was going on a tangent :P
12:23	justin_smith	sdegutis: or alternately instead of a map of maps you can have a directory of edn files staging.clj dev.clj prod.clj
12:23	justin_smith	noncom: I mean make an ajax request and in the callback put data you get from the request into the ratom in order to change parts of the page
12:24	sdegutis	justin_smith: my current approach is to use (System/getProperty "myapp.env") to get the env name, and then selecting a plain Clojure map of settings based on that.
12:24	noncom	ah i see, right
12:24	sdegutis	justin_smith: the problem with this approach is it only describes the settings for the live environment, or whether to use the memory-environment -- it can't actually switch between them.
12:24	justin_smith	noncom: websockets have a similar logic, but are faster (it's one connection that stays open instead of separate requests that get negotiated)
12:25	justin_smith	sdegutis: that's the part that component makes easier
12:25	justin_smith	shut down components, reset config, start up components
12:25	noncom	justin_smith: i used websockets a bit before. do you think that they are better than ajax in almost any case?
12:25	sdegutis	justin_smith: So each service has a default in-memory implementation, just made up of normal vars, like (defn send-email [to from subject body] ...), and there's an alternative implementation in an adjacent namespace that actually uses the real service (e.g. SES), along with a function in that namespace called go-live! which just uses alter-var-root to replace the default implementation in the other namespace with this function in t
12:25	sdegutis	his namespace.
12:25	justin_smith	noncom: I prefer them where they are supported, definitely - much smoother
12:25	sdegutis	This technique feels... a bit weird.
12:26	noncom	i see
12:26	justin_smith	sdegutis: yeah, I prefer having a component which provides the configurable part of the emailer
12:27	justin_smith	noncom: also, if you ever want such a thing, websockets free you from the request/response paradigm - you can have pushes of data in either direction, and whether that needs a response can be negotiable
12:28	noncom	yeah, i once made a prototype of an online RTS with them.. seemed really pleasant to work with
12:28	noncom	but somehow it all seems a bit clunky.. the whole web thing
12:30	sdegutis	justin_smith: Hmm. Thanks. I'll have to think on this for a while and try to wrap my head around it.
12:32	noncom	justin_smith: have you ever worked with reagent sessions + ajax?
12:33	noncom	justin_smith: now i managed to get ajax working and i got this kind of code: http://joxi.ru/Y2Lj69ehaPbWr6
12:33	noncom	feels a bit weird :D
12:35	noncom	justin_smith: btw what are you using for websockets? immutant?
12:45	oddcully	noncom: your gut feeling is right
12:45	oddcully	the more you keep stuff like this out of your html/hiccup/... the better
12:45	oddcully	tell some fn or some message bus (e.g. core async), that something needs to be done
12:46	oddcully	then let it happen and when it happended update the atom/datascript/state/...
12:46	oddcully	which the propagates into an update of the html
12:47	oddcully	s/the/&n/
12:54	sdegutis	,(-> :foo {:bar})
12:55	clojurebot	#<RuntimeException java.lang.RuntimeException: Map literal must contain an even number of forms>
12:55	sdegutis	:(
12:55	sdegutis	,(-> :foo (hash-map :bar))
12:55	clojurebot	{:foo :bar}
12:55	sdegutis	:D
12:57	sobel	gah, i can't get clojure.java.jdbc/insert! to work on my (Oracle) table to save myself. is there a special trick w/oracle?
12:57	sobel	i can select so i know the connection is there but insert! seems to generate bad sql. ORA-00926: missing VALUES keyword
13:03	sdegutis	Is there a less vacuous way of accomplishing this?
13:03	sdegutis	,(->> ["command" "web" "port" "8080"] (partition 2) (map (fn [[a b]] [(keyword a) b])) (apply concat) (apply hash-map))
13:03	clojurebot	{:command "web", :port "8080"}
13:11	ystael	sdegutis: clojure.walk/keywordize-keys
13:12	sdegutis	,(->> ["command" "web" "port" "8080"] (apply hash-map) (clojure.walk/keywordize-keys))
13:12	clojurebot	#error {\n :cause "clojure.walk"\n :via\n [{:type java.lang.ClassNotFoundException\n :message "clojure.walk"\n :at [java.net.URLClassLoader$1 run "URLClassLoader.java" 366]}]\n :trace\n [[java.net.URLClassLoader$1 run "URLClassLoader.java" 366]\n [java.net.URLClassLoader$1 run "URLClassLoader.java" 355]\n [java.security.AccessController doPrivileged "AccessController.java" -2]\n [java.net.U...
13:12	sdegutis	,(require 'clojure.walk)
13:12	clojurebot	nil
13:12	sdegutis	,(->> ["command" "web" "port" "8080"] (apply hash-map) (clojure.walk/keywordize-keys))
13:12	clojurebot	{:command "web", :port "8080"}
13:12	sdegutis	ystael: I like your style.
13:12	ystael	glad i could help :)
13:15	justin_smith	noncom: sente, http-kit implementation
13:16	noncom	i see
13:34	lper	howdy, has anyone here had success using gen-class to override a protected method (javax.swing.JPanel/paintComponent) without reflection warnings?
13:44	vince`	\help
13:45	vince`	erc-list
13:46	vince`	/erc-list
13:46	vince`	//channel
13:46	vince`	/erc-list
13:47	amalloy	sobel: nobody can guess what is wrong with your insert! if you don't paste an example call to it. and of course it's possible that oracle doesn't support even the most basic sql, but i'd first guess that it's my own code
13:49	noncom	justin_smith: i am exploring the example with websockets in luminus. i did everything as in the tutorial, however, i am gettin some strange error in the server log
13:49	noncom	the response of the ws compojure handler is {:status 200, :body #<UndertowWebsocketChannel org.projectodd.wunderboss.web.async.websocket.UndertowWebsocketChannel@4fe927d1>}
13:50	noncom	so it is trying to return the websocket object as a result
13:50	noncom	but then there comes the error: Cannot JSON encode object of class: class org.projectodd.wunderboss.web.async.websocket.UndertowWebsocketChannel: org.projectodd.wunderboss.web.async.websocket.UndertowWebsocketChannel@4fe927d1
13:51	noncom	could you shed some light on this? i am sure i am not supposed to send a java object as a response body
13:51	buharin	hello
13:51	buharin	:)
13:51	amalloy	noncom: i am pretty sure you are
13:51	buharin	I start reading Clojure for the Brave and True
13:51	amalloy	it's a Channel into which stuff gets written
13:52	buharin	cause I thought I am brave and true enough to read it
13:52	amalloy	i'd guess that the issue is rather that you're wrapping a json middleware around a route that doesn't return json (instead returning a websocket)
13:52	buharin	but I am afraid that there are no jobs for clojure and it is waste of time
13:52	buharin	:(
13:52	noncom	amalloy: so, i am sending it to the html frontend? why then compojure complains that it cannot JSON-encode it ..
13:52	noncom	ah, i am supposed to encode it somehow?
13:53	noncom	buharin: that depends. actually clojure is getting pretty much of a foothold on the world-wide arena...
13:53	amalloy	i am claiming that you are probably encoding it when you're not supposed to
13:53	amalloy	probably with some json middleware, as i said
13:54	noncom	buharin: even in my country where clojure invitations are rare, i am able to apply clojure to my daily work and it gives very good results and brings pleasure
13:54	amalloy	that error is rather unlikely to be coming from compojure itself, because compojure doesn't do any json encoding
13:54	expez	anyone have a leiningen hook I can look at? The docs seem to be somewhat out of date.
13:55	noncom	amalloy: ah, so this is just some middleware getting in the way? the object should be sent without any encoding
13:55	noncom	?
13:55	amalloy	that is my guess
13:55	buharin	noncom, oh ok
13:55	amalloy	but i don't know what you are doing aside from following some tutorial
13:56	noncom	amalloy: heh, nothing else. i am actually, moving very closely to the luminus tutorial
13:56	noncom	probably the tutorial on websockets diverges from the rest of the tutorial, i will look more closely to its github repo
14:11	lambda-smith	So guys, any news on the GUI front? Is Seesaw still the best option?
14:12	justin_smith	lambda-smith: I'd say a majority of our frontends (at least out of those vocal here) are html / cljs. I've seen some people using JavaFX via interop as well.
14:13	lambda-smith	Hi see, thanks justin_smith
14:30	sdegutis	lambda-smith: yeah most people use cljs/html/reagent afaik
14:30	sdegutis	lambda-smith, justin_smith: I've toyed with using Reagent inside Electron.
14:31	lambda-smith	Yeah, it seems like web app/using Electron is the way to go nowaday.
14:31	lambda-smith	Oh well, I guess it's about time I learn Electron + Clojure web stack
14:32	sdegutis	Personally I just stuck with plain old Electron + JavaScript (+ a few libs of course). Clojure isn't a significant improvement over JS, so it's not worth the difficulties it causes.
14:32	justin_smith	man, "reagent electron" is a shitty google search
14:33	sdegutis	One of the worst in fact.
14:33	sdegutis	Extremely real science term.
14:33	justin_smith	adding javascript helped, but really now
14:33	sdegutis	Btw is the overhead of (#'foo) significantly higher than (foo)?
14:33	justin_smith	sdegutis: crit/bench will give you the info you seek
14:33	lambda-smith	sdegutis: what kind of overhead?
14:34	sdegutis	I'm considering changing my massive entry-point (defroutes ...) to have things like #'user-routes instead of user-routes for dynamic reloading to work better.
14:34	sdegutis	CPU I guess.
14:34	justin_smith	lambda-smith: it needs to do the var indirection on every call
14:34	sdegutis	justin_smith: never heard of that, thanks
14:34	lambda-smith	Hm.. I see
14:34	justin_smith	sdegutis: criterium.core/bench
14:34	sdegutis	(woo finally made it to reddits front page, my life's checklist is almost complete)
14:34	tcrayford____	actually so does calling it without the var quote, right?
14:35	justin_smith	tcrayford____: the difference is how often / under what circumstances lookup is forced
14:35	justin_smith	#'foo is looked up anew on every invocation, foo can be inlined, or if used as an arg to a first class function is only looked up on the invocation of said function (which may used that looked up value N times)
14:36	justin_smith	tcrayford____: in sdegutis ' usage, he passes #'foo to a handler which spends the rest of the app lifetime derefing #'foo on every usage, where if passed foo it would have only looked it up once
14:36	tcrayford____	ah, yep
14:36	tcrayford____	uh haha
14:36	sdegutis	So I guess it might be slower. But it's the JVM so probably not noticeably slower in produciton.
14:37	tcrayford____	bahaha
14:37	tcrayford____	(if (:development env) #'user-routes user-routes) it's fine
14:37	justin_smith	tcrayford____: hey we could even make a macro for that!
14:39	sdegutis	Will that thread well inside -> ?
14:39	sdegutis	Oh wait it's inside (defroutes) not (->)
14:51	sdegutis	It's not working.
14:52	sdegutis	My code isn't noticing my redefined function.
15:03	sdegutis	What could cause a redefined function (redefined with `C-c C-k` while CIDER is running) to not be seen and used by the running code?
15:05	sobel	Can anyone help me figure out how to diagnose my fairly fundamental problem getting clojure.java.jdbc/insert! to work...at all?
15:06	sobel	i can query but insert! complains: SQLSyntaxErrorException ORA-00926: missing VALUES keyword
15:08	sdegutis	Please Help. I ran (jetty/run-jetty #'my-handler {:port 8080}) and now inside CIDER I evaluated (defn my-handler [] {:status 200 :body "ok so far"}) and refresh but the change is not visible.
15:08	sdegutis	What am I doing wrong??
15:08	lazybot	sdegutis: Definitely not.
15:09	mdeboard	what
15:09	mdeboard	@ lazybot
15:09	sdegutis	mdeboard: lazybot has really lame responses programmed in for when you type ?? at the end of something
15:10	sdegutis	It's annoying but you learn to just get used to it.
15:10	mdeboard	oh
15:14	clojurian	Hi, I'm having trouble with dynamic reloading using CIDER. First I ran (run-jetty #'my-handler). Loaded my page and the handler shows. Now, inside CIDER, I evaluated a new definition of my-handler using C-x C-e, and refreshed my browser, but the change is not visible. What am I missing or doing wrong?
15:15	justin_smith	$mail sdegutis so not even an exception thrown because your handler got an arg and you didn't define it to take one?
15:15	lazybot	Message saved.
15:15	mdeboard	Sure clojurian is sdegutis
15:15	mdeboard	Surely*
15:16	clojurian	Well there goes my one shot at trying to ask this question of all those who have me on /ignore
15:16	justin_smith	I still haven't found this thing called "electron" that can be used in combination with the "reagent" library because electron+reagent is just giving me a bunch of chemistry results
15:16	TimMc	mdeboard: I was confused why you said that, but it's probably based on messages I had ignroed.
15:16	sdegutis	justin_smith: Oh I thought you knew what it was already.
15:17	sdegutis	justin_smith: https://github.com/atom/electron/
15:17	justin_smith	OK they renamed atom
15:17	justin_smith	I know what atom is
15:17	sdegutis	justin_smith: right not even an exception was thrown
15:17	justin_smith	*was
15:17	sdegutis	justin_smith: no they renamed atom-shell
15:17	mdeboard	TimMc, lol
15:17	sdegutis	justin_smith: Atom is still Atom
15:17	mdeboard	I have no idea who sdegutis is, was just trying ot help out justin_smith :P
15:17	sdegutis	What did TimMc say?
15:17	TimMc	because surely a complaint about cider being weird is not very specific.
15:18	justin_smith	OK
15:18	sdegutis	I can't see it at all but I don't have him on ignore.
15:18	sdegutis	Ooooh.. I see.. TimMc private messaged mdeboard to let him know I'm a troll he should /ignore.
15:18	sdegutis	Friendliest community ever. A+.
15:18	mdeboard	I regret so much about my actions in the last 5 minutes now
15:18	mdeboard	pretend I said nothing
15:18	sdegutis	done
15:18	sdegutis	justin_smith: no exception, nothing
15:19	sdegutis	not in the emacs-cider-repl, not in the terminal repl.. nothing
15:19	cfleming	$mail snowell: That's great, thanks! You can reformat using Code->Reformat Code, or whatever you have that bound to (the menu will show you). If you have code selected, only that code will be reformatted.
15:19	lazybot	Message saved.
15:19	cfleming	$mail hante_monsta: You can configure all the indentation in Cursive - if you're having problems doing that, let me know.
15:19	lazybot	Message saved.
15:21	sdegutis	Okay already #clojure, I can take a hint. Enjoy your peace and quiet without trolls like me ruining it.'
15:22	TimMc	mdeboard: Consider the logs wiped.
15:22	TimMc	but now my messages to you look weird!
15:22	mdeboard	I appreciate your business advice re: my frozen yogurt stand
15:27	TimMc	:-)
15:29	amalloy	sobel: i already gave you a suggestion
15:30	amalloy	as you can see if you scroll back, my suggestion was to gist an example insert! that's not working. otherwise the only thing we have to work with is "it doesn't work", and the only useful advice to give is "have you tried turning it off and back on again?"
15:38	sobel	amalloy: i didn't see that earlier. i eventually narrowed it to problems mapping tags to table names
15:52	host	Hello beautiful Clojuristas! I've recently changed OS to Windows (needed Photoshop). Is Clojure development on that OS plausible? Or pain in the bum?
15:55	Rurik	host, use an IDE for sanity
15:55	host	Rurik: Light Table + Leiningen is enough?
15:56	Bronsa	host: I'd suggest IntelliJ
15:56	host	Bronsa: Why?
15:56	Bronsa	with cursive
15:56	Bronsa	host: cursive is really good
15:56	Bronsa	https://cursiveclojure.com/
15:56	host	Bronsa: Does it have instant feedback?
15:56	Bronsa	it's easy to setup and really powerful
15:57	host	or instarepl of some sort?
15:57	Bronsa	host: it has an integrated repl
15:57	Bronsa	no, not like lighttable's instarepl
15:57	host	Bronsa: instarepl is a killer feature for me
15:57	host	so I guess cursive is not in my type
15:58	host	but I will look at it
15:58	Bronsa	oh well, then it sounds like light table is actually what you want :)
15:58	host	I've also had issues with \n and \r\n here, are pitfalls like this common on Windows?
15:59	host	like these*
16:00	tdammers	sheesh... you don't need an IDE for clojure
16:01	Rurik	tdammers, command line on windows sucks
16:02	tdammers	did I say "command line"?
16:03	vaitel	I'm using Emacs + cider on windows; it seems to work pretty well.
16:03	Bronsa	tdammers: nobody said you need an IDE
16:04	ashwink005	can anyone tell me how do I make a sqlite db SELECT call
16:05	ashwink005	SELECT * FROM database WHERE id=x name=y
16:05	ashwink005	how do I pass in the variables? i.e. x and y
16:07	ashwink005	anyone please!
16:08	host	Maybe something with "let" statement? But I'm a noob, you don't have to listen to me
16:09	ashwink005	no I know I need to call the jdbc library's function
16:09	Bronsa	ashwink005: https://github.com/ogrim/clojure-sqlite-example
16:09	ashwink005	but what and how do I pass the SELECT string
16:11	ashwink005	Bronsa: yeah how do I add arguments to the where clause
16:11	ashwink005	Bronsa: any idea? (def output (query db "select * from news"))
16:11	Bronsa	https://github.com/clojure/java.jdbc#example-usage
16:23	ashwink005	Bronsa: thanks I'll look into it
17:11	ashwink005	how do I make a post request in Clojure?
17:11	ashwink005	is the hiccup form the only way
17:12	surtn	ashwink005: clj-http should work - https://github.com/dakrone/clj-http#post
17:22	ZimaBlue`	I'm having some project.clj problem, when I add my source paths it gives me could not locate on classpath. The relevant line is: :source-paths ["src/cljs" "src/demo"] and that matches the directory structure but I always get Could not locate demo/core__init.class or demo/core.clj on classpath.
17:22	ZimaBlue`	but with the source commented out, it's fine
17:25	expez	ZimaBlue`: like you don't have a src/demo/demo/core.clj file, which is what leiningen is looking for
17:26	expez	s/like/likely/
17:26	expez	ZimaBlue`: so just change "src/demo" to "src" and you'll be good to go.
17:31	ZimaBlue`	expez: thanks, but I don't understand - is it adding together my prefixed demo in the main and suffixed demo in the src string?
17:31	expez	ZimaBlue`: the default value for source-paths is ["src" "test"], you told it to consider src/demo the root of your source directory
17:32	expez	ZimaBlue`: so if you have a namespace named demo.core then leiningen will look at the root for a folder named demo and then look for a file there called core.clj
17:33	ZimaBlue`	I think I understand, thank you!
17:57	ZimaBlue`	I'm still failing, now cljs isn't working:
17:57	ZimaBlue`	structure: src/cljs/demo/app.cljs, code: (ns demo.app)
17:57	ZimaBlue`	(.write js/document "Hello, ClojureScript!")
17:57	ZimaBlue`	config:
17:57	ZimaBlue`	:cljsbuild {:builds
17:57	ZimaBlue`	[{:source-paths ["src/cljs"] :compiler {
17:57	ZimaBlue`	:output-to "resources/public/js/app.js"
17:57	troydm	how can I make sure that cider-nrepl is loaded?
17:57	ZimaBlue`	:optimizations :whitespace
17:57	ZimaBlue`	:pretty-print true}}]}
17:57	ZimaBlue`
17:57	troydm	when I type lein repl and I have cider-nrepl in user profile in .lein/profiles.clj how can I make sure it's actually loaded?
17:59	oddcully	ZimaBlue`: please don't paste large portions of code here. use a gist/refheap/... instead
17:59	oddcully	ZimaBlue`: also "isn't working" might need some more elaboration
18:01	ZimaBlue`	sorry - what I mean is that when I go into resources, there isn't a compiled js file. I'll use that link in future - not been on irc mnuch before.
18:02	dnolen	ZimaBlue`: there's also a #clojurescript channel these days
18:03	dnolen	ZimaBlue`: I would make a gist w/ your project.clj and your project structure so people can examine that.
18:03	ZimaBlue`	ok, I'll repost the question over there. Thanks
18:13	kwladyka	Did you hear about remote job for Clojure Junior or in Europe with relocation? :)
18:45	expez	troydm: when you call cider-jack in (in emacs) you'll get a warning if the middleware is missing or misconfigured. If you want to check in `lein repl` if the middleware is active (although I can't see why) you can check for the presence of any of cider.nrepl.* namespaces
18:52	troydm	expez: ic
19:02	hiredman	/win 19
19:09	ashwink005	what does -> mean in clojure
19:09	ashwink005	can't google it
19:10	Rurik	ashwink005, threading macro
19:10	TEttinger	ashwink005: yep, there's a good resource for ungoogleable symbols in clojure
19:10	ashwink005	TEttinger: could u send me a link?
19:10	TEttinger	https://yobriefca.se/blog/2014/05/19/the-weird-and-wonderful-characters-of-clojure/
19:10	ashwink005	Rurik: thanks :)
19:16	TEttinger	ashwink005: you may also want to bookmark clojuredocs and/or grimoire
19:17	ashwink005	TEttinger: I have bookmarked clojure docs. But couldn't find the name of the operator
19:17	ashwink005	thanks man :)
19:18	TEttinger	http://conj.io/ is the quick reference page of grimoire
19:19	troydm	grimoire only contains core library right?
19:20	TEttinger	nope http://conj.io/store/v1/org.clojure/clojure/1.7.0/clj/clojure.string
19:20	TEttinger	need to click the + but it does have all the standard stuff
19:21	TEttinger	"oh you wish you were using common lisp do you?" http://conj.io/store/v1/org.clojure/clojure/1.7.0/clj/clojure.pprint/cl-format
20:23	gargsms	I am a Clojure newbie. I made a Compojure project and configured the routes. I can do GET properly but in case of POST, I get `Invalid Anti Forgery Token` error. Any help?
20:28	thearthur	gargsms: the corasponding get request should be sending you a csfr prevention token (Cross Sire Request Forgery)
20:28	gargsms	thearthur, How do I do that?
20:29	thearthur	this needs to be passed to the post request to prevent CSRF attacks (on all web applications, this is not Clojure specific)
20:29	gws	gargsms: https://github.com/ring-clojure/ring-anti-forgery
20:29	gws	gargsms: you've probably configured that, and you can either disable it for now to test your routes, or pass the __anti-forgery-token form parameter
20:35	gws	as the README mentions you can get the value that is associated with that parameter by calling ring.util.anti-forgery/anti-forgery-field
20:37	gws	which will generate the HTML necessary, rather. You can get the actual value out of a dynamic var in that lib if you want to create some custom HTML
20:47	troydm	is there a builtin function that would remove element from a list returning a new copy of list?
20:48	rhg135	rest
20:48	rhg135	or pop
20:51	justin_smith	troydm: you don't need copies of immutable data
20:51	justin_smith	rhg135: neither of those copy
20:52	rhg135	justin_smith: I didn't see the copy
20:52	rhg135	why would you want it though?
20:53	justin_smith	probably because he didn't realize clojure lists were immutable, or didn't understand the implications of that fact
20:54	justin_smith	rhg135: that was the right answer for what troydm wanted, I was just being pedantic about the assumed details
20:56	justin_smith	rhg135: clojure-blindness
20:56	rhg135	indeed
20:57	troydm	justin_smith: let's say I want to implement a function that would give me all possible permutations of a list, how would I go about implementing it? I have no clue
20:57	rhg135	being more pedantic, that is more due to the persistence
20:57	rhg135	non-persistent lists might get copied for perf
21:00	justin_smith	troydm: clojure.combinatorics has that function if you just need the functionality
21:01	justin_smith	troydm: but the general pattern in clojure is to write a recursive function where each iteration gets more results until you have created all of them
21:01	troydm	justin_smith: I know about that, but I'm more interested in implementing it by my own
21:04	justin_smith	troydm: so - how I would break it down - first take the elements of the list, and pass those as the "head" and all other members of the list as the "tail elements" for each recursive call. Then for the recursive calls generate a new set of heads and tails. recursively concatenate all results of this, stopping when each tail hits empty list
21:04	justin_smith	hmm, that's not very clear is it
21:06	troydm	justin_smith: hmm, I got general idea
21:10	gargsms	gws, I have the value. I tried passing it in the `X-Csrf-Token` header from the browser. I still get the same error.
21:17	gws	you're getting the value from the server and sending it back on each POST, or you've copied the value from some point in time and are passing that to test?
21:17	gargsms	Ah. Finally. Somehow I got it working.
21:17	justin_smith	troydm: here's a broken version that shouldn't be far from working https://www.refheap.com/109034
21:17	gargsms	Thanks thearthur gws
21:18	troydm	justin_smith: ic, thx
21:19	justin_smith	,((juxt take drop) 3 (range 10))
21:19	clojurebot	[(0 1 2) (3 4 5 6 7 ...)]
21:22	TEttinger	I can't remember, does the group of all permutations of a, say, 10-element list include 1-element and 2-element sublists or just re-orderings of the 10-element?
21:25	justin_smith	TEttinger: "a rearrangement of the elements of an ordered list into a one-to-one correspondance with itself"
21:25	TEttinger	if order doesn't matter, that's a combination, not a permutation right?
21:25	justin_smith	if order doesn't matter, permutation isn't defined
21:26	TEttinger	(and there are less comb's than perm's)
21:29	TEttinger	like if the store sells 6 kinds of fruit, and I can buy any number of any of the kinds of fruit, and I want to know how many item numbers will be on the receipt (so quantity doesn't matter if > 0), that's a combination (there are 63 here, since you don't get a receipt if you buy nothing)
21:29	TEttinger	but if it was something like arranging 6 different fruits in a line on a table, that's a different problem
21:54	justin_smith	TEttinger: well I figured out a way to do it, but it feels like a silly solution https://www.refheap.com/109034
21:55	justin_smith	I am sure that can be golfed down to like 1/4 the size
22:06	TEttinger	justin_smith: yeah I think you're right about the size
22:06	TEttinger	,(let [limit 6] (nth (iterate #(for [p %, n (range (inc (count p)))] (concat (take n p) [(count p)] (drop n p))) [[0]]) (dec limit)))
22:06	clojurebot	((5 4 3 2 1 ...) (4 5 3 2 1 ...) (4 3 5 2 1 ...) (4 3 2 5 1 ...) (4 3 2 1 5 ...) ...)
22:06	TEttinger	&(let [limit 7] (nth (iterate #(for [p %, n (range (inc (count p)))] (concat (take n p) [(count p)] (drop n p))) [[0]]) (dec limit)))
22:06	lazybot	Execution Timed Out!
22:06	TEttinger	haha
22:06	TEttinger	&(let [limit 5] (nth (iterate #(for [p %, n (range (inc (count p)))] (concat (take n p) [(count p)] (drop n p))) [[0]]) (dec limit)))
22:06	lazybot	⇒ ((4 3 2 1 0) (3 4 2 1 0) (3 2 4 1 0) (3 2 1 4 0) (3 2 1 0 4) (4 2 3 1 0) (2 4 3 1 0) (2 3 4 1 0) (2 3 1 4 0) (2 3 1 0 4) (4 2 1 3 0) (2 4 1 3 0) (2 1 4 3 0) (2 1 3 4 0) (2 1 3 0 4) (4 2 1 0 3) (2 4 1 0 3) (2 1 4 0 3) (2 1 0 4 3) (2 1 0 3 4) (4 3 1 2 0) (3 4 1 2 0) (... https://www.refheap.com/109038
22:07	TEttinger	there should be 120 elements there
22:07	justin_smith	fancy
22:07	justin_smith	I'm bad at lazy stuff
22:08	TEttinger	it can be quickly adapted to just get the nth item from the original list, too
22:09	TEttinger	&(let [limit 5 original [:a :b :c :d :e]] (map (partial map nth original) (nth (iterate #(for [p %, n (range (inc (count p)))] (concat (take n p) [(count p)] (drop n p))) [[0]]) (dec limit))))
22:09	lazybot	java.lang.UnsupportedOperationException: nth not supported on this type: Keyword
22:09	TEttinger	aww
22:10	TEttinger	&(let [limit 5 original [:a :b :c :d :e]] (map #(map (partial nth original) %) (nth (iterate #(for [p %, n (range (inc (count p)))] (concat (take n p) [(count p)] (drop n p))) [[0]]) (dec limit))))
22:10	lazybot	⇒ ((:e :d :c :b :a) (:d :e :c :b :a) (:d :c :e :b :a) (:d :c :b :e :a) (:d :c :b :a :e) (:e :c :d :b :a) (:c :e :d :b :a) (:c :d :e :b :a) (:c :d :b :e :a) (:c :d :b :a :e) (:e :c :b :d :a) (:c :e :b :d :a) (:c :b :e :d :a) (:c :b :d :e :a) (:c :b :d :a :e) (:e :c :b ... https://www.refheap.com/109039
22:11	TEttinger	I had a bit of help from wikipedia and 14th century math whizzes in India :)
22:11	justin_smith	haha, cheater
22:11	TEttinger	https://en.wikipedia.org/wiki/Permutation#Generation_in_lexicographic_order
22:12	TEttinger	(that's not the algo I used though)
22:12	TEttinger	this one, with no opts https://en.wikipedia.org/wiki/Steinhaus%E2%80%93Johnson%E2%80%93Trotter_algorithm
22:16	chouser	can I play?
22:16	justin_smith	oh, please do
22:16	justin_smith	with any luck I might learn something
22:17	chouser	&((fn perm [r m p] (if (> m 0) (mapcat #(comb (disj r %) (dec m) (conj p %)) r) [p])) '#{a b c d e} 5 [])
22:17	lazybot	java.lang.RuntimeException: Unable to resolve symbol: comb in this context
22:17	chouser	heh
22:17	justin_smith	what is comb ?
22:17	chouser	&((fn perm [r m p] (if (> m 0) (mapcat #(perm (disj r %) (dec m) (conj p %)) r) [p])) '#{a b c d e} 5 [])
22:17	lazybot	⇒ ([a e c b d] [a e c d b] [a e b c d] [a e b d c] [a e d c b] [a e d b c] [a c e b d] [a c e d b] [a c b e d] [a c b d e] [a c d e b] [a c d b e] [a b e c d] [a b e d c] [a b c e d] [a b c d e] [a b d e c] [a b d c e] [a d e c b] [a d e b c] [a d c e b] [a d c b e] [... https://www.refheap.com/109040
22:17	justin_smith	ahh
22:17	justin_smith	nice!
22:17	chouser	Works with sets, so no good if the input it meant to have duplicates.
22:19	chouser	That's an oldie, btw. 11 June 2008.
22:19	justin_smith	it's a classic problem, that just happens to hit some aspects of clojure programming I am pretty bad at
22:21	chouser	oh, I didn't mean to suggest you were bad at anything, just that I was cheating off my former self.
22:21	justin_smith	oh, no, I volunteered that part :)
22:22	justin_smith	that's the reason I was asking for improvements / other approaches
22:22	chouser	If you always want the full set of inputs:
22:22	chouser	&((fn perm [r p] (if (seq r) (mapcat #(perm (disj r %) (conj p %)) r) [p])) '#{a b c d e} [])
22:22	lazybot	⇒ ([a e c b d] [a e c d b] [a e b c d] [a e b d c] [a e d c b] [a e d b c] [a c e b d] [a c e d b] [a c b e d] [a c b d e] [a c d e b] [a c d b e] [a b e c d] [a b e d c] [a b c e d] [a b c d e] [a b d e c] [a b d c e] [a d e c b] [a d e b c] [a d c e b] [a d c b e] [... https://www.refheap.com/109041
23:14	justin_smith	someday I hope to attain this level of craftsmanship http://i.imgur.com/BUpsUAF.gifv
23:29	TEttinger	(inc chouser)
23:29	lazybot	⇒ 23
23:30	TEttinger	justin_smith: IS THAT TRANSPARENT WOOD
23:32	justin_smith	TEttinger: it's wood cut so incredibly thin that you can see through it
23:32	justin_smith	by hand
23:32	TEttinger	and I thought the joins they do were amazing
23:32	TEttinger	wow
23:32	jeaye	Is it the technique or the tool?
23:32	justin_smith	an act of remarkable skill and handicraft - he probably spent decades getting that good
23:32	justin_smith	jeaye: I'm sure the tool is a part of it too
23:33	justin_smith	anyway, metaphorically it is all about how much he crafted and honed his craft which is what will inspire me to become a better programmer
23:34	TEttinger	https://www.youtube.com/watch?v=W1pvUlQgYtk
23:36	justin_smith	TEttinger: having worked on American mcmansion style construction sites, the comparison is really embarrassing
23:36	TEttinger	I can imagine!
23:37	justin_smith	it's amazing what these guys do with hand tools
23:41	TEttinger	it's interesting because japan doesn't have endless quantities of lumber that they could just throw more sequoias at a building project, and doesn't have much iron that historically could have been used for mass-producing large heavy weapons (like the horribly successful 10-15-foot spike of metal called a pike and used heavily by disposable peasants in european wars)
23:41	TEttinger	japan's traditional building techniques emphasize not wasting materials
23:42	TEttinger	it makes you wonder about what scarcities drive programming innovation
23:43	justin_smith	TEttinger: developer attention span and discipline
23:43	justin_smith	which leads us to things like fp and OO which at least in theory keep the worst outcomes from happening when we forget what we were doing :)
23:43	TEttinger	clojure got a lot of attention initially because the multicore revolution was starting, and it seems to have already ended, but clojure is still (thankfully) in use
23:46	TEttinger	it seems like a lot of clojure's big new ideas are going to be needed for future developments (GPU programming could really benefit from some kind of immutability when you have hundreds or thousands of tiny compute units)