#clojure – 2013-04-30

2013-04-30

00:00	technomancy	postgres devs should know better =\
00:00	callen	I really wish Clojure on Android didn't have such a slow startup time.
00:01	hiredman	to be fair 1.5 is pretty old
00:01	hiredman	even 1.6 is supposed to be EOL any day now
00:02	j4x0n	Apparently they've done it before. It was fixed then someone must have recompiled.
00:02	technomancy	hiredman: actually it's just Oracle's JDK that is going to be EOLed
00:02	technomancy	OpenJDK has no such plans
00:04	callen	OpenJDK performs just fine as well, anecdotally.
00:09	tieTYT	here's some code I converted from java. How could this be changed to be more idiomatic? https://www.refheap.com/paste/43d1ca29fe152a2cd3f80f1cb
00:11	callen	tieTYT: the manual type-checking and dorun usage is very meh.
00:11	callen	as is the direct interaction with Swing.
00:12	callen	tieTYT: http://daveray.github.io/seesaw/ at least use it pedagogically, if not actually in your thing.
00:12	tieTYT	callen: I don't think I can use seesaw for this
00:12	tieTYT	if you assume that, how could I avoid the manual type-checking?
00:13	callen	tieTYT: that is very unfortunate. learn from seesaw then.
00:13	callen	tieTYT: learn more Clojure and you'll get your answers re: avoid manual type-checking.
00:14	tieTYT	callen: I've been reading seesaw source for days now
00:15	brehaut	tieTYT: is the purpose of the type check to ensure that its not nil or something?
00:15	brehaut	and if you want real type checking, theres a library for that
00:15	tieTYT	brehaut: it's to ensure that it is a JComponent. If it's not a JComponent, it won't have a getInputMap
00:15	callen	brehaut: (instance? ...)
00:15	tieTYT	and getComponents returns Component, not JComponent
00:16	brehaut	callen: obvious its instance at the moment, but i presume theres a reson for the check if its ported from java
00:17	tieTYT	if I don't do that check, it could try to call getInputMap on an instance that doesn't have that method
00:23	brehaut	well, if you need polymorphic functions, protocols are probably a better way to go about it
00:23	brehaut	you can implement protocols for nil or object if needed
00:23	brehaut	for your default behaviours
00:23	brehaut	this is assuming you are passing non-compliant objects into the function
00:24	tieTYT	i'm always passing a JComponent in
00:24	tieTYT	does that mean i shouldn't use protocols?
00:25	brehaut	if you always pass in something that supports that method then no protocols, no type checks
00:25	brehaut	just dont go passing the wrong thing in
00:26	tieTYT	line 11 may pass in a Component that's not a JComponent
00:26	tieTYT	i thought you meant me as in what the programmer passes in
03:04	noprompt	does anyone use pre/post conditions?
03:05	noprompt	i rarely see them used "in the wild" but the seem useful.
03:06	Raynes	noprompt: Not really.
03:07	murtaza52	is it possible to short circuit a `reduce`, like what `some` does
03:10	Raynes	murtaza52: In Clojure 1.5 you can return (reduced) to stop the reduce.
03:10	Raynes	But only in 1.5+
03:11	noprompt	Raynes: yeah. so i take it no one uses them.
03:12	noprompt	well, what's a clean way to assert arguments meet a certain criteria?
03:12	Raynes	&(doc assert)
03:12	lazybot	⇒ "Macro ([x] [x message]); Evaluates expr and throws an exception if it does not evaluate to logical true."
03:12	Raynes	noprompt: But if you're gonna use assert, might as well use pre conditions and shit.
03:12	Raynes	I mean, just because nobody uses them doesn't mean they aren't perfect for your usecase.
03:12	Raynes	They were added for a reason.
03:13	Raynes	Very little is in Clojure that Rich didn't think was useful.
03:14	sw2wolf	Does Rich has id in this channel ?
03:14	noprompt	the AssertionError could be a bit cryptic though for a function in a public api.
03:14	tgoossens	sw2wolf: yes
03:14	sw2wolf	Is it Rich ?
03:15	sw2wolf	i just want to highlight it in my ERC configuration
03:15	Raynes	noprompt: Well, then throw ex-info instead.
03:15	Raynes	rhickey
03:15	tgoossens	I know that rich has been on IRC in the past. But I don't know about now
03:15	Raynes	He isn't here right now. Doesn't come very often.
03:15	Raynes	When he does it's rhickey.
03:16	tgoossens	whats with all the 'idiomatic'. I seriously never encountered a community that used the word 'idiomatic' so often
03:16	noprompt	Raynes: ex-info?
03:16	Raynes	&(doc ex-info)
03:16	sw2wolf	Now i have erc-pals '("Hindley" "rhickey")
03:16	lazybot	⇒ "([msg map] [msg map cause]); Alpha - subject to change. Create an instance of ExceptionInfo, a RuntimeException subclass that carries a map of additional data."
03:16	Foxboron	tgoossens: you can't come from Python.
03:16	Raynes	You're not very good at this, are you noprompt?
03:17	Raynes	:p
03:17	Foxboron	tgoossens: the Python community uses "idiomatic" all the time.
03:17	Foxboron	"idiomatic python! idiomatic classes! idiomatic this and that!"
03:17	noprompt	tgoossens: so does the Ruby community too.
03:17	Foxboron	http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html
03:17	noprompt	Raynes: my brain is a little fried i guess. :/
03:18	Raynes	noprompt: <3
03:18	noprompt	i've been working on porting this legacy application at work to Clojure.
03:18	Raynes	&(throw. (ex-info {:some :data :about :the :exception})
03:18	lazybot	java.lang.RuntimeException: Map literal must contain an even number of forms
03:18	Raynes	&(throw. (ex-info {:some :data :about :the :exception}))
03:18	lazybot	java.lang.RuntimeException: Map literal must contain an even number of forms
03:18	Raynes	FUUUU
03:18	Raynes	&(throw. (ex-info {:some :data :about :the :exception :okay}))
03:18	lazybot	java.lang.IllegalArgumentException: Unable to resolve classname: throw
03:18	Raynes	ffffffffffuuuuuuuuuu
03:18	Raynes	&(throw (ex-info {:some :data :about :the :exception :okay}))
03:18	lazybot	clojure.lang.ArityException: Wrong number of args (1) passed to: core$ex-info
03:18	noprompt	Raynes: that happened to me last week. :P
03:19	Raynes	&(throw (ex-info "Goddamn it." {:some :data :about :the :exception :okay}))
03:19	lazybot	clojure.lang.ExceptionInfo: Goddamn it. {:about :the, :some :data, :exception :okay}
03:19	Raynes	Thank you.
03:19	Raynes	&(try (throw (ex-info "Goddamn it." {:some :data :about :the :exception :okay})) (catch ExceptionInfo e (ex-data e)))
03:19	lazybot	java.lang.SecurityException: You tripped the alarm! catch is bad!
03:19	Raynes	Oh blow me lazybot.
03:20	noprompt	but gawd. the application is a maze of 6-year-old php and javascript (interleaved of course).
03:20	murtaza52	I have a seq of vectors. I want to iterate through them. Modify only the first vector that meets a pred. Return back the coll with the modified vector.
03:21	Raynes	&(doc ex-data)
03:21	lazybot	⇒ "([ex]); Alpha - subject to change. Returns exception data (a map) if ex is an ExceptionInfo. Otherwise returns nil."
03:21	murtaza52	How do I do the above? bcoz all methods such as for and reduce will modify all vectors that meet the pred, while I want to modify only the first that meets the criteria.
03:21	Raynes	noprompt: So my code should work. As an example.
03:21	Raynes	noprompt: ExceptionInfo is basically an exception that doesn't suck and allows you to pass data out.
03:21	tgoossens	and with idiomatic i guess you mean "conventional" ?
03:22	noprompt	Raynes: that's neat-o.
03:23	noprompt	gonna try it out in the repl real quick.
03:23	itemad	http://www.youtube.com/watch?v=UrMWRAaFdIc&feature=youtu.be
03:23	itemad	ops! :-P
03:26	noprompt	hmm... i'm debating whether i should add a dependency, steal code, or hand-roll a color lib for garden.
03:27	tomoj	murtaza52: https://www.refheap.com/paste/7dc0b0d3e81f5ed63c7b4d589 hmm, surely there is a better way?
03:27	noprompt	aren't those always the choices? geeze. i think i need a drink...
03:28	Foxboron	tgoossens: idiomatic is an idiom. It could be obscure code which is widely known to be the "right" way. Think of it as language idioms. "Break a leg" is an idiom.
03:28	tomoj	I would like to write it as something like (update-in vecs [map (some pred)] f)
03:29	tomoj	(hypothetical)
03:29	tomoj	(.. and probably confusing because the names 'map and 'some are taken. ignore me)
03:32	noprompt	Raynes: i guess what i like about the pre conditions is that it can make something like (if (meets-criteria x) do-stuff (throw ...)) a bit cleaner.
04:12	Odinodin	Given I run lein test, when a test fails, the process just hangs and I have to manually stop it. Does anyone know if there is anything to get around that?
04:13	noprompt	/quit
04:20	noidi	Odinodin, maybe you have a thread that's still alive and blocking the app from exiting
04:22	noidi	I think you can use VisualVM to see what's going on while the process hangs http://docs.oracle.com/javase/6/docs/technotes/guides/visualvm/
04:23	Odinodin	noidi: ah, thanks, that seems very probable. We have a jetty server running during the tests thats probably the culprit
04:26	nbeloglazov	What is the usage of symbols in edn format? I cannot find any real use case for them.
04:29	tomoj	datomic is an example where they are used
04:30	tomoj	the rest interface accepts queries like [:find ?x :where [?x :foo]] as edn
04:33	tomoj	I guess datomic shows two use cases: representing binding in edn, and referring to clojure vars
04:37	tomoj	my intuition is that the space of symbols in a language encoded in edn will tend to be more closed (less open) than the space of keywords
04:38	tomoj	hmm
04:39	tomoj	I guess the difference is really more just that keywords are supposed to mean themselves where symbols can be assigned particular meanings
04:48	nbeloglazov	tomoj: thank you
05:09	no7hing	does anybody know of a java/clojure lib similar to https://github.com/jubos/fake-s3 ?
05:11	jaley	no7hing: are you just trying to stub out an S3 server for testing purposes?
05:11	jaley	no7hing: jClouds' blobstore abstraction has a stub provider implementation, which can be useful for that
05:12	no7hing	@jaley yes
05:12	no7hing	@jaley i'll have a look at it, thanks
05:16	jaley	no7hing: if you depend on [org.jclouds/jclouds-blobstore "1.6.0"] in your project.clj
05:17	jaley	no7hing: you can then (:require [org.jclouds.blobstore2 :as blob]) and use (blobstore "transient" "" "") to get a fake instance
05:17	jaley	no7hing: all of the blob/put-blob blob/get-blob will work with it, storing entries in ram
05:18	jaley	no7hing: I believe there's also a filesystem implementation if you need it
05:18	no7hing	ram only sounds perfect for my needs
05:19	no7hing	i'll just pre-populate the blobstore with my data and don't need to tamper with the application code, as it's tested from another vm
05:20	jaley	no7hing: presumably you also want your code to actually talk to S3 later?
05:20	jaley	no7hing: when you want to plug into s3, you need to add a dependency on the s3 "blobstore" provider to your project and create an instance of that with (blobstore "aws-s3" "access-key" "secret-key") instead
05:20	no7hing	already doing it
05:20	jaley	no7hing: cool
05:21	no7hing	thanks for your help!
05:21	jaley	no7hing: no problem
05:49	nbeloglazov	Is there some clojure expression that is not valid edn expression?
06:00	tomoj	nbeloglazov: ::foo
06:00	tomoj	among others..
06:00	tomoj	#(foo)
06:00	tomoj	@foo
06:01	tomoj	#'foo
06:01	nbeloglazov	:) Ok, thanks
06:01	tomoj	though
06:01	tomoj	those last ones are all sort of cheats
06:01	tomoj	(fn [] (foo))) and (deref foo) and (var foo) are all valid edn..
06:02	tomoj	#java.net.URI["/foo"]
08:48	CookedGryphon	Hey all. So I don't much like the try/catch form in clojure. I find it always produces ugly, hard to follow, hard to re-use and hard to compose code. What i do instead is in this gist: https://gist.github.com/AdamClements/5488162 what do people think of this? I'm tempted to make it a library, but a dependency and a require feel like overkill for one/two macros!
08:51	clgv	CookedGryphon: probably, you do not know "dire" https://github.com/MichaelDrogalis/dire
08:52	clgv	CookedGryphon: that lib allows you to decouple error handlers from the functions they might appear in
08:53	clgv	CookedGryphon: as well as pre-/post-hooks
08:53	CookedGryphon	clgv: I do know dire, I find it's overkill for most of my use cases
08:53	CookedGryphon	and does var rebinding, which I don't really like
08:54	CookedGryphon	as it's all too easy to miss that your error handling is subverting your code path, making it hard to read
08:55	clgv	CookedGryphon: but you can really dcouple the handlers from code which is one step further than your macros
08:55	CookedGryphon	if you see (defn times [a b] ...) and then something which calls (times 2 3), you'd expect it to go straight into that function, which could lead to unpredictable behaviour if you've actually rebound the times var
08:56	CookedGryphon	I feel it's a step too far and has the potential to reduce readability, especially if you're reading someone else's code and aren't used to dealing with errors in that way
08:56	clgv	CookedGryphon: well, that's what documentation is for. if you have a coding guideline for error handlers of this kind in your project - you'll expect that those handlers will kick in
08:57	clgv	CookedGryphon: it is certainly a matter of personal taste. but I'd choose dire before those macros in the gist, since using them consistently also makes the code quiet complex.
08:58	CookedGryphon	my point is, someone's going to see this, think great, write a separate namespace for handlers (to keep similar things bundled together), gleefully rebind these variables. Someone else comes along and they're missing half the code but don't even realise it because there's no reference to the error stuff
08:58	clgv	CookedGryphon: but that is a documentation problem.
08:59	CookedGryphon	not really, it's an evident code problem
08:59	CookedGryphon	I don't want to have to read a manual on how this particular codebase handles errors, that sounds like the java way of doing things
09:00	Morgawr	what function can I use if I want to update all the values of a hashmap without touching the keys?
09:00	Morgawr	like a map but only on the values
09:00	clgv	Morgawr: there is none. you can build it via reduce-kv
09:01	Morgawr	I'll try, thanks
09:01	CookedGryphon	Morgawr: I believe there's something in the flatland/useful library which does that
09:01	Morgawr	CookedGryphon: I'm using ClojureScript so I can't really rely on external libraries
09:02	clgv	Morgawr: if you change all values you actually build a new map even if you use assoc. since there does not remain much for structural sharing
09:02	CookedGryphon	Morgawr: fair enough, you could copy the implementation though
09:04	Morgawr	clgv: the thing is, I have a hashmap that contains all filenames and I want to append a different extension at the end of said filenames (to distinguish between .mp3 and .ogg sounds depending on the browser)
09:06	clgv	Morgawr: (defn update-map-values [m f & args] (persistent! (reduce-kv (fn [r, k, v] (assoc! r k (apply f v args))) (transient {}) m)))
09:06	clgv	Morgawr: you might also add the key to the function invocation
09:06	Morgawr	oh wait
09:07	Morgawr	I found a much easier way
09:07	Morgawr	http://stackoverflow.com/questions/1676891/mapping-a-function-on-the-values-of-a-map-in-clojure this seems pretty good
09:07	Morgawr	and it works :)
09:07	clgv	Morgawr: yes that works. the reduce-kv is the faster approach in Clojure - dont know about ClojureScript
09:09	Morgawr	I don't really need speed at the moment though, it's a very simple function. Thanks either way :)
09:11	LiaoPengyu	Hello?
09:11	clojurebot	BUENOS DING DONG DIDDLY DIOS, fRaUline LiaoPengyu
09:11	LiaoPengyu	javadoc
09:11	LiaoPengyu	ToUpperCase
09:51	xeqi	Raynes: ping; what kind of info do you scrape off clojars for lazybot?
09:57	no7hing	is there a fast way to add a virtual host to ring/jetty?
09:57	weavejester	no7hing: A virtual host is just dispatching off the Host header
09:58	weavejester	In Compojure, you can write: (context "http://subdomain.example.com/" [] ...)
09:59	weavejester	At least in theory...
09:59	no7hing	@weavejester i didn't get them to show up in the app, but haven't gone for those context's though
09:59	weavejester	Actually, it would probably be better to write:
09:59	weavejester	(ANY "http://subdomain.example.com/" [] (routes …))
09:59	weavejester	I know that one works
09:59	weavejester	Not sure about the context
09:59	no7hing	will try that, thanks
10:00	weavejester	But you can always dispatch off the (get-in request [:headers "host"]) anyway
10:00	no7hing	i understood them to be a way to bundle up handlers;
10:00	no7hing	but that's just e
10:00	no7hing	me
10:00	no7hing	was thinking too complicated. again.
10:00	weavejester	The context macro is a way to add a common prefix to a set of routes.
10:01	no7hing	what i thought
10:01	no7hing	but couldn't express
10:08	mefesto	any know if the docs for weavejester/{hiccup,compojure} currently in a transition? Seems like the links are broken and no css
10:09	mefesto	http://weavejester.github.io/hiccup
10:09	weavejester	mefesto: Looks like github.io domain shift broke the redirect
10:10	weavejester	http://weavejester.github.io/hiccup/
10:10	weavejester	If you add an ending / it works
10:10	mefesto	weavejester: ahh thank you
10:10	weavejester	Not sure how to fix that for a static site...
10:11	weavejester	I guess I should alert github to the issue. "/foo" should redirect to "/foo/"
10:12	wink	yeah
10:13	Anderkent	technomancy: https://github.com/technomancy/leiningen/blob/master/src/leiningen/pom.clj#L234
10:13	Anderkent	(if (seq extra-src) (add-test-sources)) ? :(
10:13	mefesto	weavejester: it loads the index page correctly but the resources within the page are relative (js/blah.js) whereas (/hiccup/js/blah.js) would fix it
10:14	weavejester	mefesto: Yes, but that would require the docs to know where they are being deployed to.
10:14	mefesto	maybe i shouldn't say `fix it` but work-around it
10:14	mefesto	weavejester: ah i see
10:15	weavejester	Ideally the docs should work as local files as well
10:15	weavejester	Which means relative links
10:15	mefesto	yeah definitely wouldn't want to sacrifice that.
10:16	mefesto	knowing to put a slash at the end is enough for me :)
10:19	kasterma	I just run into some confusing (for me) behaviour of equality. See https://gist.github.com/kasterma/5489015. It seems declared but unset symbols are treated specially for =.
10:20	kasterma	Is it that, or am I missing something in the behaviour of '?
10:22	clgv	kasterma: thats symbol versus variable value
10:23	kasterma	Could you explain a little more?
10:23	clgv	kasterma: those list constructions are not the same: (def x 42) (list x) => (42), '(x) => (x)
10:25	kasterma	(= (list \|) dd) => true
10:25	kasterma	Ahh, but why did it work with a keyword?
10:25	clgv	keywords evaluate to themselves
10:26	kasterma	So in the equality test the content of the list is evaluated, and evaluating \| doesn't work?
10:27	clgv	kasterma: in that expression you construct a list with a single element which is the value that is bound to \|
10:27	kasterma	Which does not exist.
10:28	clgv	kasterma: \| is unbound and thus returns an instance of clojure.lang.Var$Unbound which is an implementation detail
10:29	kasterma	clgv: thx, for the help.
10:30	mefesto	when using lein-ring and lein-cljsbuild is a typical workflow for generating a standalone jar something like the following or is there another way? lein cljsbuild prod && lein ring uberjar
10:32	mefesto	ideally, i'd like to only have to issue `lein ring uberjar` and have cljs build with all the optimizations for production
10:35	clgv	kasterma: a simple rule to remember: only use '(1 2 3 4 5) to construct list of constants
10:35	ucb	when I eval this I get :default, where am I going wrong? (condp <= 1 0xff "yes" 0xffff "no" :default)
10:36	clgv	,(<= 1 0xffff)
10:36	clojurebot	true
10:37	kasterma	clgv: thx
10:38	ucb	,(<= 1 0xff)
10:38	clojurebot	true
10:38	clgv	&(condp >= 1 0xff "yes" 0xffff "no" :default)
10:38	lazybot	⇒ "yes"
10:38	akells`	Is a [B not a bytearray? I'm trying to call .length on something that is a [B and its telling me 'no matching field found: length for [B'
10:38	clgv	the application of arguments is the other way round in condp
10:39	clgv	quote: " & & & & & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 1 & & & & \\"
10:39	clgv	oops
10:39	nDuff	akells`: there's an alength function
10:39	clgv	quote: "For each clause, (pred test-expr expr) is evaluated."
10:39	nDuff	akells`: ...Java exposing it as a field is syntactic sugar.
10:39	ucb	clgv: ooh, nice, thanks
10:39	ucb	clgv: totally misread that
10:40	akells`	nDuff: that seems to be working. is this the length, in bytes?
10:40	akells`	thank you very much, by the way
10:40	clgv	ucb: I would have guessed for (pred expr test-expr) as well
10:40	nDuff	akells`: number of array elements, so for a byte array, yes.
10:40	ucb	nod
10:40	akells`	much appreciated!
11:26	akells`	Is this going to actually concatenate these two byte arrays? Or is my repl misleading me a little bit by saying it returns one? (byte-array (concat (.getBytes "edf") (.getBytes "abc")))
11:33	xeqi	(let [x 3 _ (println x) y (+ 1 2) _ (println y)] y)
11:33	xeqi	&(let [x 3 _ (println x) y (+ 1 2) _ (println y)] y)
11:33	lazybot	⇒ 3 3 3
11:33	gfredericks	(let [a (b), :do (things), c (d)] ...)
11:33	gfredericks	xeqi: yeah, I use that for debugging. feels to awkward to use for real code
11:58	dnolen	ibdknox: congrats on the latest release!
11:59	ibdknox	dnolen: thanks :)
12:10	seangrove	ibdknox: Yes, it seemed very well received on hn, great job
12:10	n_b	I'll second that!
12:10	n_b	It's helped get a few of my friends into Clojure :)
12:43	saolsen	that js integration is great, does it work that well for clojurescript?
13:00	dnolen	saolsen: LT is written entirely in ClojureScript as far as I know and I believe ibdknox uses LT to dev LT, so I imagine it works OK. Would like to see more docs on that tho.
13:04	ibdknox	saolsen: dnolen: because of the way cljs works, you'd have to do some weird things to get the same level of eval. For one, it requires replacing the source of a file, which means you'd have to completely recompile on every eval :/
13:05	ibdknox	that being said, LT gets around this because of the BOT architecture - everything is late bound
13:09	dnolen	ibdknox: hmm, why do you need to re-compile the whole file if you just want to change a single def?
13:09	ibdknox	dnolen: because I need the complete output of bootstrap.js or whatever you call the cat'd source
13:10	dnolen	stuartsierra: can we do another CLJS at some point? It's been a while. Main changes would be Clojure 1.5.0 dependency and data.json 0.2.2
13:10	stuartsierra	will do
13:10	stuartsierra	may need updating since Sonatype Nexus change — I'll look into it
13:11	dnolen	ibdknox: oh this is for dev'ing LT directly, I guess less a problem if you're using LT to dev your own CLJS stuff?
13:11	dnolen	stuartsierra: 1.5.1 I meant
13:11	stuartsierra	ok
13:11	ibdknox	dnolen: nope, this is for the VM patching for any CLJS. You can always do normal eval, which is actually more than enough in most cases for CLJS
13:12	ibdknox	dnolen: but to do the same things I was showing in the cube video, I have to replace the original source file with a new one and they have to be relatively similar - so I would need the new result of compilation to swap it out with
13:21	dnolen	ibdknox: hmm make some sense ... is there some way you see to make that process smoother?
13:22	wink	hm, anyone ever tried to put json into mysql via korma? looks like an encoding problem, but it's weird
13:22	saolsen	I've been working on a cljs game and that level of interaction with a threejs canvas would be the greatest thing ever
13:40	ibdknox	saolsen: depending on how you write your game, you may not need that stuff
13:41	ibdknox	dnolen: I haven't though through it too far yet. There may be something clever to do.
13:54	akells`	clojure.java.io/copy should be able to handle any byte array, correct?
13:56	amalloy	akells`: i doubt it
13:57	amalloy	well, i guess it does. it implicitly creates a Reader from it. okay
13:57	amalloy	er...an InputStream
13:57	akells`	I must be doing something else wrong. It works fine with a byte array from an image file
13:57	akells`	but it doesn't seem to be working quite the same with a byte array from a text/html file
13:58	akells`	well, its actually a byte array that is a concat of two other byte arrays. but it works fine for the concat that uses an image file's byte array, but not for the concat that uses a text/html file's byte array
13:59	amalloy	well that's obviously a red herring. the jvm doesn't remember where arrays came from
14:00	akells`	I just wanted to make sure clojure.java.io/copy should work in any case. sounds like I've got an issue somewhere else. this was helpful, thanks amalloy
14:01	_francis_	I'm looking at this code https://www.refheap.com/paste/14081 and wondering why you would put a type in a function metadata - thoughts anyone?
14:05	arrdem	_francis_: one day god willing we will have optional typing able to take advantage of that data
14:05	_francis_	arrdem: thanks
14:06	arrdem	_francis_: actually no. in this case you are type-hinting the function.
14:06	_francis_	arrdem: I thought that type hints go in the arg list?
14:07	arrdem	_francis_: you can put them there too.
14:07	arrdem	_francis_: I'm not clear on the details, but I understand that it type-specializes the generated code. Used for performance and for Java interop.
14:09	_francis_	arrdem: Are you certain that types in the metadata will be used for type-hinting? In this case the fn will return that type, but can accept several different types.
14:09	arrdem	_francis_: that's why I say I'm not sure. I'
14:10	arrdem	ve seen argument metadata used to clamp down the function dispatch time, but I'm not sure what effect typing the return value has.
14:11	_francis_	Could you supply an example?
14:12	svedubois	In CLJS, how can I set some value inside a "doto".
14:12	svedubois	For example, I have this:
14:12	svedubois	(set! (.-color sphere) "red")
14:12	svedubois	And I would like to have something like this:
14:12	svedubois	(doto (sphere.)
14:12	svedubois	(.-color "red"))
14:13	dnolen	_francis_: the compiler will use that information, it makes interop less tedious
14:14	dnolen	_francis_: for example if you locally bind the result of invoking that function in let, that type hint will be propagated by the compiler
14:14	_francis_	dnolen: Awesome.
14:14	arrdem	dnolen: thanks for the save :p, didn't know (let) could use type hinting
14:15	arrdem	_francis_: I can't find it ATM but I believe that the community matrix library is the last place I saw hinting in the wild.
14:16	dnolen	arrdem: most of binding forms really as they generally macro expand to let
14:16	matko	hi #clojure, I was wondering, in a multi-threaded environment, is it a bad thing to have many threads lying around that do nothing? For example, 5000 threads that mostly sleep but wake up now and then to update something? Or does this incur little cost?
14:16	dnolen	now that I think about it, I think all?
14:17	technomancy	matko: IIRC the primary cost there is creating and destroying threads; I think once they're around they're supposed to be cheap. but you might want to look into a thread pool anyway to avoid re-inventing the wheel
14:17	arrdem	dnolen: everything but def should macroexpand to a let at the end of the day
14:17	matko	technomancy: futures already use a threadpool right?
14:17	matko	I was thinking of using futures for this
14:17	n_b	futures use the agent thread pool I believe
14:17	matko	hm.. is that bad?
14:17	matko	I'd assume that means the send-off pool
14:18	n_b	That's my understanding
14:18	technomancy	matko: it just means you don't have a lot of control over it
14:18	technomancy	may or may not be a problem in practice
14:18	matko	ok, so startup is costly, but a sleeping thread is not a bad thing
14:18	matko	thank you :)
14:18	technomancy	well, not on a decently-sized linux system
14:19	matko	what about windows?
14:19	n_b	matko: I just did a pretty large threaded importer, and ended up using threadpools because I had tens of thousands of threads bein created when I just used futures
14:19	technomancy	matko: no idea about windows or mac
14:19	matko	ok
14:19	n_b	but it was a memory consumption issue due to my workload
14:19	matko	I'll have to test
14:19	technomancy	virtualized linux also might not be so hot
14:19	technomancy	you'll have to test anyway; don't trust random advice on IRC =)
14:19	matko	hahah, that's advice I will trust
14:19	stuartsierra	Futures use the Agent send-off thread pool.
14:19	n_b	Benchmark both ways, and remember IFn implements Runnable so you can always (.new (Thread. #(some_fn))
14:20	matko	woah, I forgot about that
14:20	matko	thanks for reminding
14:20	stuartsierra	In Clojure 1.5 you can configure the thread pools, e.g. set bounds.
14:20	n_b	matko: It makes using Executors much easier :)
14:20	matko	does clojure come with libraries for thread pools?
14:21	n_b	matko: Outside the basic concurrency constructs, not to my knowledge. Using Java interop was very easy IME
14:21	stuartsierra	matko: java.util.concurrent
14:22	n_b	Though IRC did much to help fill the gaps in my knowledge of it
14:22	matko	stuartsierra: that's not clojure :) but sure that works
14:22	stuartsierra	Clojure generally makes little effort to hide details of its host platform.
14:22	antares_	matko: agents use a thread pool and can be (ab)used very similarly to executes in j.u.c.
14:23	matko	j.u.c.?
14:23	technomancy	clojurebot: j.u.c?
14:23	clojurebot	Titim gan éirí ort.
14:23	matko	.... scary
14:23	technomancy	clojurebot: java.util.concurrent?
14:23	clojurebot	java.util.concurrent is "When I find myself in times of trouble / Prof. Doug Lea comes to me / Coding lines of wisdom / j.u.c."
14:24	matko	oh doh
14:24	nDuff	matko: RH has been pretty explicit about building Clojure's concurrency primitives to supplement, not replace, java.util.concurrent.
14:24	matko	cool, so I guess I'll prototype using futures. If it turns out to be problematic, I'll switch to a thread pool. either way should work fine for my purposes
14:24	tcrayford	man do I love that j.u.c. thing. That's cscotta or somebody like that originally?
14:24	technomancy	tcrayford: tnm
14:26	nDuff	matko: If a future isn't the right thing for the job, don't be shy about going straight to j.u.c. Clojure functions implement both Runnable and Callable; there's nothing at all difficult about using them with the Java APIs.
14:27	tcrayford	technomancy: oh, of course. I'm sad that dude deleted all his tweets, he was the best
14:27	technomancy	what; he did?!
14:27	matko	hm. I should have a good look at that library anyway. Guess I'll do so now
14:27	technomancy	weird
14:27	tcrayford	yeah :(((
14:27	technomancy	well it's immortalized in clojurebot now
14:31	matko	oh, I guess the thing I actually want is a scheduled thread pool. good thing I looked
14:47	xorola	is clojure strongly typed? i think so.
14:47	technomancy	xorola: yes
14:49	SegFaultAX	xorola: Java is strongly typed, yes.
15:01	ToBeReplaced	how can i extend the Closeable interface to an existing type i don't own? extend-type yells b/c Closeable is an interface, not protocol
15:03	ToBeReplaced	for personal use, of course... i want to take a jzmq context which has a .term destructor that matches libzmq and make it usable from clojure with with-open
15:04	xeqi	you can't directly. One option is (proxy Closeable ...) and decorate the object
15:04	gfredericks	hmm
15:04	gfredericks	promises can't act like futures by throwing exceptions on deref can they :/
15:04	xeqi	hmm, I think I want reify there
15:04	xeqi	instead of proxy
15:05	xeqi	can never remember which until I try
15:05	gfredericks	oh nevermind I can combine futures and promises in a magical mystery way
15:05	ToBeReplaced	yeah reify would work, it would also muck with the type which might make reflections not happy, but i suppose that makes sense
15:05	ToBeReplaced	thanks
15:25	svedubois_	I have a vector (def v ["a" "b" "c"])
15:25	svedubois_	And I would like to create a classname for each element in the vector in only one line.
15:25	svedubois_	Is it possible, how?
15:25	svedubois_	(def a (classname.))
15:26	SegFaultAX	svedubois_: What do you mean create a classname? Why does it have to be one line?
15:27	svedubois_	One global variable for each element in the vector
15:28	svedubois_	With the vector ["a" "b" "c" ... ], create (def a (classname.)), def b ..., def c ...
15:29	SegFaultAX	svedubois_: Why do you want to do this?
15:31	amalloy	yeah, that is not a thing you want to do
15:33	matko	(map #(eval `(def ~(symbol %))) v)
15:34	gdev	,(map class [0.07 "james" :bond])
15:34	clojurebot	(java.lang.Double java.lang.String clojure.lang.Keyword)
15:40	svedubois_	ClojureScript can list all files in a given directory?
15:41	gfredericks	probably in whatever manner you would normally do that in javascript
15:41	gfredericks	which is "no" in a traditional browser setting
16:17	arrdem	can I add hooks to a lein command? so "ring server" triggers "lessc" in my specific case.
16:25	technomancy	arrdem: :prep-tasks ["lessc"] will cause lessc to happen before any code runs inside a project
16:25	arrdem	technomancy: thanks
16:25	technomancy	lessc needs to be fast if there's no work to do, because it'll trigger on every repl, complie, test, etc
16:26	arrdem	it's pretty fast atm since it doesn't seem to be building my CSS files -_-
16:26	technomancy	fast is good
16:26	arrdem	silent failure is bad tho
16:28	wink	hmm. (clojure.java.io/copy (clojure.java.io/input-stream "http://...x.png") (clojure.java.io "/path/to/foo")) copies one image and not another. reproducably. any ideas? :)
16:29	wink	*add /output-stream ofc where needed
16:42	gdev	my eyes, they bleed, warning: java code https://www.refheap.com/paste/af945a051690ee85ec1d018cf
16:43	Raynes	gdev: This is beautiful code.
16:43	Raynes	I strive to write this kind of code in Clojure.
16:44	arrdem	Raynes: not sure if sarcasm
16:44	Raynes	arrdem: Sarcasm.
16:44	arrdem	gud
16:44	iwo	hey, does anyone know of an example on how to create a vector of keys that is compatible with get-in/assoc-in/update-in FROM a map?
16:44	mthvedt	clojure is not type-safe and enterprise-ready, it cannot make code that beautiful
16:44	Raynes	I think amalloy wrote something to do that.
16:45	amalloy	doesn't ring a bell, sorry
16:45	iwo	so i have a nested map structure - i'm trying to decide how I could navigate this map to create all valid keys for get-in
16:45	Raynes	amalloy: You wrote a function to get all possible keyseqs from a map.
16:45	Raynes	amalloy: I know you did because we discussed the implementation.
16:45	Raynes	Don't screw with me, bro.
16:45	amalloy	i write a lot of functions. i don't remember this one
16:46	gdev	L.A. GUI with an Oakland back end
16:48	amalloy	it's not hard to write, though
16:48	amalloy	https://www.refheap.com/paste/5823c0e842a3948b579c42cc5
16:49	amalloy	modulo your decision about whether (:b) is a valid answer as well
16:49	Raynes	amalloy: I'm greping every piece of code you ever wrote until I find the one you wrote in the first place.
16:51	amalloy	it actually comes out a lot nicer if you're willing to count (:b) as a keyseq: https://www.refheap.com/paste/5885807c958f35ab9b80976c1
16:51	Raynes	I can't remember the bloody project.
16:51	Raynes	Jiraph? Telemetry? BAH.
16:51	Raynes	This is going to haunt me.
16:53	arrdem	Raynes: you were right, noir -> compojure wasn't that bad at all.
16:56	Raynes	arrdem: Whoa, you just now did it?
16:56	arrdem	Raynes: yeah I just got the user facing parts of my site ported in the last two hours
16:56	ppppaul	i want to output a JSON stream from my ring endpoint (using cheshire, and can't really figure out how to get an input-stream form it's generate-stream fn
16:56	ppppaul	any help
16:57	ppppaul	:)
16:57	gfredericks	ppppaul: oh there was something for this
16:58	arrdem	Raynes: once I got about 15 github documentation pages open it was dead easy
16:58	Raynes	arrdem: Worth it!
16:58	arrdem	ppppaul: someone hacked this live here a few months ago....
16:58	gfredericks	ppppaul: first find ring.util.io/piped-input-stream
16:58	ppppaul	gfredericks, i found some issues on cheshire and ring about this, but i'm looking for a hacked up solution now :)
16:59	ppppaul	i have the piped-input-stream src open...
16:59	gfredericks	then make your body (piped-input-stream (fn [out] (->> out (OutputStreamWriter.) (BufferedWriter.) (json/generate-stream data))))
16:59	ppppaul	i know i'm going to use it, and i know where to use it, but the cheshire stuff is what i'm tripping over
16:59	ppppaul	gfredericks, woooooo thanks so much :D
17:06	ppppaul	this is now a part of my liberator fork
17:06	ppppaul	woot
17:07	ppppaul	never has seeing a data dump from datomic felt so good
17:08	ppppaul	feel like watermelon
17:09	gfredericks	:)
17:09	gfredericks	I should pass on credit to whoever gave me that snippet in the first place
17:09	gfredericks	I have no idea who that was
17:09	gfredericks	(inc anonymous)
17:09	lazybot	⇒ 1
17:09	arrdem	(inc clojure) ;; since gfredrics is passing
17:09	lazybot	⇒ 11
17:10	gdev	yay, this works, but it seems hacky and amateurish which is a good description of my coding style so not surprising https://www.refheap.com/paste/cbb89e7032d2418dc20d66c84
17:11	gdev	gfredericks:) I'm still working on that database thing you helped me with; doseq on the update statement meant my update to database call was 1 to 1
17:12	gfredericks	gdev: how do you do updates without that being the case?
17:12	gfredericks	I've often wanted that
17:12	gdev	gfredericks:) I'll let you know when I figure it out =)
17:12	gfredericks	ha
17:13	gdev	having the data pre-staged was half the battle
17:15	gfredericks	ppppaul: ha I started that issue
17:15	ppppaul	:)
17:16	gfredericks	somebody, I think weavejester, pointed out at some point that the ring spec might need some amending to handle cases like this
17:17	gfredericks	not basic json, but any kind of streaming that involves an open resource
17:18	asteve	a coworker is trying to pull in a clojure project and is getting checksum errors on com/google/guava; he is using leiningen 2.1.x and we tried remove ~/.m2
17:19	asteve	26 days ago the developers for guava claimed they pushed a corrected checksum and that it would propagate over the next few hours
17:19	asteve	any ideas?
17:21	stuartsierra	dnolen: FYI, ClojureScript release build will need some changes to accommodate new Sonatype Nexus version.
17:21	stuartsierra	I'm burnt out now but I'll try to get to it this week.
17:29	asteve	this is the exact problem a coworker was having earlier today http://stackoverflow.com/questions/15818219/failed-retrieving-guava-libs-from-maven
17:29	asteve	we tried lein clean and we tried removing ~/.m2 entirely
17:30	asteve	is there a way to download the dep manually?
17:30	arrdem	asteve: your best bet is probably gonna be to force lein to load without checks...
17:30	arrdem	asteve: not sure how to do that tho.
17:31	technomancy	asteve: you can always build from source
17:31	technomancy	mvn install or whatever
17:31	technomancy	turning off checksum checks is pretty sketchy
17:31	arrdem	oooh yeah
17:31	technomancy	would strongly not recommend leaving checksum checks off
17:31	gdev	gfredericks:) sorry, I didn't mean ratio of database calls to update statement, im still trying to figure out how to interpret this oracle database trace file
17:31	technomancy	maybe turn it off once, download the dep, and turn it back on
17:31	technomancy	asteve: sometimes bad checksums get stuck on a specific mirror
17:32	technomancy	so only users from certain geographic locations see them
17:32	asteve	ah
17:32	technomancy	anyway you should definitely continue to communicate with the maintainers
17:32	asteve	ok
17:32	technomancy	until it's resolved upstream all you have are workarounds
17:38	iwo	hey, is there a neat way to do 'cons if not nil' in clojure?
17:38	arrdem	,(cons 1 nil)
17:38	clojurebot	(1)
17:38	iwo	basically: (if x (cons x l) l)
17:39	arrdem	oh identity over list?
17:39	iwo	i suppose i could do: (keep identity (cons x l))
17:39	arrdem	,(doc keep_
17:39	clojurebot	#<RuntimeException java.lang.RuntimeException: EOF while reading>
17:39	iwo	but that's even less neat :)
17:39	arrdem	,(doc keep)
17:39	clojurebot	"([f coll]); Returns a lazy sequence of the non-nil results of (f item). Note, this means false return values will be included. f must be free of side-effects."
17:40	arrdem	no that's neater, it's just not gonna do what you want.
17:40	iwo	?
17:41	iwo	this would work: (keep identity (cons x l))
17:41	iwo	i.e. cons regardless, but use keep identity to remove x if it was nil
17:42	iwo	what i'd really like is (if x (cons x l) l)
17:42	iwo	but in a single fn from clojure core :)
17:42	technomancy	iwo: useful's "fix" function might do that
17:42	technomancy	nothing in core though
17:42	amalloy	iwo: (keep identity (cons x l)) doesn't do what you want at all
17:42	amalloy	it will remove all the nils that were already in the list
17:43	sw2wolf	,(doc identity)
17:43	clojurebot	"([x]); Returns its argument."
17:43	iwo	amalloy: not a problem for me, the list contains no nils
17:43	arrdem	amalloy: thanks, I didn't think it would behave but I wasn't sure what it _would_ do :p
17:44	iwo	technomancy: do you mean flatland/useful?
17:44	technomancy	iwo: yeah, but amalloy would know for sure
17:44	amalloy	fix can kinda do it, but it's awkward: (fix l x (partial cons x)) would work most of the time, or (fix l (not (nil? x)) (partial cons x)) to be careful
17:45	amalloy	i don't think i'd use fix for this
17:45	technomancy	yeah, it's an awkward request =)
17:45	amalloy	(concat (keep identity [x]) l)?
17:45	amalloy	but that's much harder than the simple (if x (cons x l) l)
17:46	amalloy	i think test-> in 1.5 does a decent job of it, doesn't it?
17:47	amalloy	(test-> l x (->> (cons x))) probably works
17:47	amalloy	,(doc test->)
17:47	clojurebot	Gabh mo leithscéal?
17:53	iwo	i guess clojurebot doesn't speak 1.5
17:54	iwo	(if x (cons x l) l) it is :)
17:57	mthvedt	is there a way to make a private defrecord, say Foo, and not have it expose ->Foo
17:58	gfredericks	mthvedt: you could muck with the var if you really wanted to
17:59	amalloy	mthvedt: this sounds like a great opportunity to use a hashmap instead of a record
17:59	gfredericks	haha
17:59	gfredericks	amalloy the hashmap salesman
18:00	amalloy	my hashmaps provide genuine, FDA-certified constant-time lookup time, won't you try one?
18:01	gfredericks	would "unused arguments" be a good kibit rule?
18:01	gdev	amalloy:) are they organic?
18:01	arrdem	amalloy: but can you optimize them out to structs at runtime?
18:01	amalloy	i was aiming more for the 1950s "door-to-door salesman" archetype, not the 2000s-era organic stuff
18:01	tcrayford	amalloy: I only use grass-fed, home grown vegan kosher paeleo primal hashmaps, you got any of those?
18:02	mthvedt	amalloy: can your hash maps implement protocols? :P
18:02	gdev	tcrayford:) lol at vegan paeleo
18:02	amalloy	use multimethods! technomancy is probably willing to put on an evangelism act to match my salesmanship, telling you how protocols are the devil
18:03	tcrayford	true story, I know a dude who's on something like that. Asking him "what he eats" leads to a pretty short list
18:03	technomancy	be free of their tyranny
18:03	PudgePacket	Hi, I'm having some trivial problems importing jara .jars for a clojure project. I'm not sure where to keep the .jar, and how the import should refer to it, I'm used to C++ style of using a filename!
18:03	mthvedt	they are not my protocols
18:03	amalloy	technomancy: i'm afraid to google "jack chick tract"
18:03	tcrayford	technomancy: I use a protocol for this core abstraction (of data storage) in my app. Please be mad
18:03	Glenjamin	amalloy: i can't seem to find test->, did you mean cond-> ?
18:03	technomancy	tcrayford: there is still hope for you
18:03	amalloy	~repeatability
18:03	clojurebot	repeatability is crucial for builds, see https://github.com/technomancy/leiningen/wiki/Repeatability
18:03	tcrayford	how do I teach clojurebot shit?
18:03	tcrayford	~amalloy
18:04	clojurebot	amalloy is the spotlight illuminating my dumb mistakes
18:04	arrdem	loooool
18:04	amalloy	Glenjamin: i probably do. i didn't pay attention to the renaming thing
18:04	gdev	~nDuff
18:04	clojurebot	Please don't use pastebin.com: there are lots of annoying animated ads. Instead, try http://refheap.com, an ad-free pastebin written in Clojure.
18:04	arrdem	PudgePacket: amalloy is telling you to import your jars to maven and then make them lein deps
18:04	arrdem	PudgePacket: as of lein 2 lein no longer supports local non-maven jars
18:05	Glenjamin	,(doc cond->)
18:05	clojurebot	"([expr & clauses]); Takes an expression and a set of test/form pairs. Threads expr (via ->) through each form for which the corresponding test expression is true. Note that, unlike cond branching, cond-> threading does not short circuit after the first true test expression."
18:05	PudgePacket	arrdem, can i just use maven commands in lein? I only have leiningen
18:05	arrdem	clojurebot: remember arrdem is about 85% corect
18:05	clojurebot	'Sea, mhuise.
18:05	tcrayford	technomancy: also this app has a "util" namespace where I rewrote "keys" and "values" to be sane, also wrote get so it throws an exception if the key isn't there. Be more mad.
18:05	technomancy	tcrayford: non-nilling get is great
18:05	arrdem	PudgePacket: don't think so. you'll need maven to manipulate ~/.m2 in any reasonable way.
18:05	technomancy	but "util" is sad times
18:06	tcrayford	technomancy: I should just open up clojure.core right?
18:06	technomancy	totes
18:06	djwonk	I am using `bz2-reader` from http://www.paullegato.com/blog/reading-bzip2-files-clojure/ but I'm having a problem with it: https://gist.github.com/bluemont/8e8b717a732446fc9a8e#file-core-clj-L61
18:06	tcrayford	realtalk, I wish nil didn't exist. Clojure doesn't technically need it except for interop
18:07	Glenjamin	what is a good way to deal with "util" aka random bucket of functions i wish were in core?
18:07	Glenjamin	also, what's so bad about Protocols?
18:08	arrdem	it's clojurebot: forget <phrase>, right?
18:09	tcrayford	clojurebot: forget forget
18:09	clojurebot	It's greek to me.
18:12	PudgePacket	arrdem, I've downloaded and got maven working, do i just perform a similar task to running a lein operation ? navigate to project directory then run the command?
18:15	arrdem	PudgePacket: http://www.pgrs.net/2011/10/30/using-local-jars-with-leiningen/
18:19	PudgePacket	arrdem, it says there is no project object model in the directory, im running from the project directory, do i need to create a POM somehow?
18:20	Glenjamin	xeqi: am i missing something, or does kerodon not handle select elements?
18:20	SegFaultAX	PudgePacket: Probably a good idea to read a tutorial on Maven.
18:21	PudgePacket	SegFaultAx, i'm just trying to use a local .jar file in my clojure code, this seems a pretty ridiculous amount of fiddling to get something so trivial working :/
18:24	technomancy	tcrayford: "except for interop" is kind of a really big thing though =(
18:24	technomancy	but I would love a nil-free clojure
18:25	tcrayford	ofc ;). In a modern dynamically typed lang, with Maybe supplied by the lang, there's no need for nil (in my book)
18:26	Glenjamin	is Maybe actually an improvement over nil?
18:27	Glenjamin	doesn't it just move the nil along to some point where you need a value?
18:29	tcrayford	it's different
18:29	tcrayford	Maybe as a return type says "this quite possibly will return nothing"
18:29	tcrayford	usually you have to dig in non-existent docs or read the code to find out if something can return nil
18:30	mthvedt	what's the point of maybe without type checking and/or pattern matching
18:30	Glenjamin	^^ this
18:30	tcrayford	if you look at a function, and what you get out of it is a nil, then you know you have to handle the nil case
18:31	tcrayford	wheras if you look at a function, often you don't know if there is a nil case, then fail to handle it, then your program blows up in weird and wonderful ways
18:31	technomancy	it just forces awareness, right?
18:31	tcrayford	without pattern matching/monads/type checking, yeah
18:31	mthvedt	so, the point of maybe is to replace java annotations
18:31	mthvedt	got it
18:33	Glenjamin	but where do you write the Maybe return type in a dynamic language?
18:34	technomancy	docstring
18:34	technomancy	the point is, you can't not handle maybe
18:34	tcrayford	also, you'd see it when you called the function at the repl
18:35	Glenjamin	right, you have to unpack it
18:35	Glenjamin	i see
18:35	technomancy	like a reference type
18:37	SegFaultAX	"The point of maybe is to replace Java annotations" wut.
18:38	hiredman	if you fail to handle nil you aren't using mapcat enough
18:41	mthvedt	segfaultax: sarcasm
18:41	amalloy	(def easy-version-of-technomancy's-annoying-Maybe-fn (comp fromJust technomancy's-annoying-Maybe-fn)) ;; now i don't have to handle maybe anymore!
18:42	Anderkent	amalloy: fromJust throws on Nothing, surely
18:42	Anderkent	it wouldnt return nil
18:43	amalloy	Anderkent: of course, that's the joke. you're back to exceptions, just like you wanted
18:43	amalloy	not you specifically, of course
18:45	Glenjamin	xeqi: going to see if i can get dropdown support into kerodon, the enlive stuff is a bit black-magicky to me though - will send a PR if i get something reasonable
18:46	technomancy	I imagine haskell users look upon nil with the same disdain exception users look upon languages that use numeric error codes as return values
18:47	Anderkent	Sounds reasonable to me - I think nils are the source of more than half of the bugs i introduce
18:48	Anderkent	Oh, you forgot to initialize your map values to sets? Here, let me give you a nil so that you can conj onto it and break the code mysteriously 20 calls later :)
18:49	Glenjamin	isn't that basically what happens if you use Maybe with do notation in haskell?
18:50	Glenjamin	the Monad composition just shuffles the Nothing along?
18:50	Anderkent	sure, but that's not what my problem is
18:50	Anderkent	the problem is that conj eats the nil happily
18:50	Anderkent	and gives you back a list :)
18:50	SegFaultAX	Glenjamin: That's the whole /point/ of Maybe.
18:50	SegFaultAX	Anderkent: nil is the empty list.
18:51	Glenjamin	is there a conj-set ?
18:51	SegFaultAX	conj-set?
18:51	Anderkent	I know, that's why this problem exists? If conj threw up on nil, I'd get errors at the failure point. But it doesn't, so I only get errors in some random other place that expects a set but sees a list
18:51	Glenjamin	a conj that always gives you a set :p
18:52	SegFaultAX	Anderkent: conj is fine. You should be correctly checking for errors in your data.
18:53	Anderkent	I should have a map type that throws on non-existing keys, instead of silently pretending there was a nil in it
18:54	Glenjamin	or better yet, a map type that gives you empty sets on new keys
18:54	Anderkent	well not quite, because it's rare you'd want an empty set for every key
18:54	Anderkent	it's like
18:54	Glenjamin	in this case
18:55	Glenjamin	something like python's defaultdict, unsure if that fits the clojure model really
18:55	dnolen	And even tho the MLs got rid of null, ya still got the empty list to produce show stopping runtime errors - http://stackoverflow.com/questions/4883169/why-im-getting-exception-prelude-head-empty-list
18:55	Anderkent	you have some state, you store it as (def my-state (ref {:id-ste #{} :some-other-map {}})) and then somewhere else you have (update-in my-state [:id-set] conj new-id)
18:56	dnolen	c'est la vie
18:56	Anderkent	like what kind of idiom would prevent this from blowing up?
18:56	Anderkent	never conj in update-in?
18:57	SegFaultAX	Anderkent: Is it exceptional for the key to not be present?
18:57	hiredman	,(doc fnil)
18:57	clojurebot	"([f x] [f x y] [f x y z]); Takes a function f, and returns a function that calls f, replacing a nil first argument to f with the supplied value x. Higher arity versions can replace arguments in the second and third positions (y, z). Note that the function f can take any number of arguments, not just the one(s) being nil-patched."
18:57	brehaut	dnolen: something something dependant types and total functions something handwaves solves that problem just fine
18:58	Anderkent	SegFaultAX: yes, the key is only not present because of the typo in original declaration
18:58	dnolen	brehaut: ;)
18:58	Glenjamin	oh, i see
18:59	Glenjamin	if all you're worried about is typos, you're probably ok
19:00	Anderkent	I don't think "don't make typos" is a solution
19:01	Glenjamin	write some tests to express behaviour, you'll catch them soon enough
19:01	Glenjamin	or take a typing class, i don't class typos as one of the major problems in software development
19:08	Anderkent	That was uncalled for. Whatever, I'm probably more likely to use something like (defn sget [map key] (when-not (contains? map key) (throw ...)) (map key)). I can imagine at least 2 ways in which even full test coverage wouldn't catch a similar update-in conj issue, but since it seems you never make mistakes I won't bother
19:10	SegFaultAX	Glenjamin: Humans are prone to typing errors. Some non-trivial percentage of programs are types by humans. Therefore some non-trivial percentage of programs are prone to typing errors. To categorically exclude typing errors as a source of bugs in software is utterly short-sighted.
19:10	Glenjamin	sorry, that came across as snarky, wasn't intended that way
19:11	Glenjamin	if you're concerned that typos will be a major source of bugs, then you probably want a statically typed language?
19:11	SegFaultAX	Glenjamin: Humans are the source of bugs.
19:12	Glenjamin	which is why we write automated tests, and abstractions :)
19:12	SegFaultAX	Glenjamin: Automated tests can only capture at most a certain subset of all possible errors. Likewise with static typing. There is no silver bullet.
19:13	Glenjamin	agreed
19:14	Glenjamin	i'm not claming i never make typos or introduce bugs
19:14	Glenjamin	i'm claiming that I don't introduce enough bugs from typos to change my entire approach to development to attempt to avoid them
19:15	Glenjamin	i feel like my tone isn't transferring very well though :(
19:17	brehaut	actually, you dont need static typing to catch typoes; clojure eliminates a large number of typo causing errors by requiring all symbols to be defined before they are reference lexically
19:17	SegFaultAX	Or at least declared.
19:17	brehaut	obviously whenever strings and keywords etc enter the mix, you reintroduce the potential for that type of typo
19:18	brehaut	yeah sorry
19:18	SegFaultAX	As is the case in lots of languages that have forward decls.
19:18	SegFaultAX	(Dynamic or otherwise)
19:18	brehaut	(yup
19:19	tieTYT2	is there a function/library that takes a POJO and converts it into a clojure data structure?
19:19	SegFaultAX	On a related tangent, I've never really understood the justification for variable hoisting in JS.
19:19	brehaut	(clojure,set/subset? static-types static-analysis)
19:19	SegFaultAX	tieTYT2: Records are POJOs
19:19	tcrayford	dnolen: re the head of an empty list case, that's been a long complain of mine for haskell. Head should return a Maybe.
19:20	brehaut	also the bean function
19:20	tieTYT2	SegFaultAX: my java pojo already exists. Is that an issue?
19:20	tieTYT2	ooh bean function
19:20	SegFaultAX	tieTYT2: Oh then you'll probably have to write a converter for it.
19:20	SegFaultAX	pojo->map or something.
19:20	tieTYT2	SegFaultAX: well it looks like bean would work?
19:20	brehaut	tieTYT: it creates a proxy thoguh, not a persistent structure
19:20	tieTYT2	am I wrong?
19:20	tieTYT2	aw
19:21	tieTYT2	it says it's read-only
19:22	SegFaultAX	Plus the bean function is probably a lot more expensive than it's worth if you're converting a lot of these objects.
19:23	SegFaultAX	I don't really know anything about how HotSpot may or may not optimize lots of reflective calls.
19:23	tieTYT2	k, i'll write my own converter
19:25	tieTYT2	here's what I'm trying to do. I've got a list of this POJO. For shitty reasons, its equals() impl is worthless. I need to find instances in the list that are the same based off of specific fields and only keep the instance with the earliest date. Then I need to take the ones that are the same based on a DIFFERENT set of fields, copy the data (except for a primary key field) over to the
19:25	tieTYT2	instance with a primary key... etc.
19:26	tieTYT2	to me this sounds like a functional problem and it'd be easier to do in clojure. This is a javaee app and the class is an entity
19:27	Glenjamin	you might be as well just breaking into small functions for each step like you would in clojure, but staying on the java side
19:28	tieTYT2	Glenjamin: it's really hard to do that without a useful equals(). The collections have to be mutated along the way
19:28	tieTYT2	and it's hard to figure out what's going on
19:28	Glenjamin	are the fields public?
19:28	tieTYT2	no, but you can get them through getters
19:28	hiredman	(->> objs (group-by identity-function) vals (map (partial sort-by date-of)) (map first) (group-by second identity) vals (map (partial apply merger)))
19:28	hiredman	that should be second-identity
19:29	Glenjamin	just have your service class define it's own domain specific equals() function
19:29	tieTYT2	hiredman: yeah that's a shitload of code in java IMO
19:29	hiredman	and there is no need to make maps
19:30	Glenjamin	that certainly looks better than my idea :)
19:30	tieTYT2	hiredman: are you advocating what Glenjamin's suggesting with your comment?
19:31	hiredman	I dunno, I have Glenjamin on ignore
19:31	Glenjamin	:(
19:31	tieTYT2	sounds like a no
19:34	tieTYT2	hiredman: why'd you mention the maps thing?
19:34	tieTYT2	did you mean no need for a converter?
19:35	hiredman	yes
19:35	tieTYT2	ah, cool
19:35	tieTYT2	i'll try it out, thanks
19:37	Glenjamin	i take it all back, i just got a mysterious null pointer error from deep in the stack :(
19:40	amalloy	check for typos
19:41	Glenjamin	heh, forgot to save a file :(
19:42	Raynes	I read "heh, forgot to save a life :("
19:43	tieTYT2	is this out of date? The second one looks like what I want to do
19:43	tieTYT2	http://stackoverflow.com/questions/2181774/calling-clojure-from-java
19:43	tieTYT2	it says: No need to call RT.init() anymore
19:43	tieTYT2	but it only works if I do
19:44	djwonk	My bzip2 problem was that I needed to use the second constructor form. Groan: http://www.paullegato.com/blog/reading-bzip2-files-clojure/
19:44	djwonk	Who knew that bzip2 files could be concatenated anyways?
19:45	tieTYT2	gives me this: java.lang.ExceptionInInitializerError at clojure.lang.Compiler.<clinit>(Compiler.java:47)
19:45	djwonk	Making the default be false, which breaks stuff when you don't expect it, is crazytown.
20:22	gdev	,(#(* %)#_(if youre happy and you know it print a one)(*))
20:22	clojurebot	1
20:22	ToxicFrog	MY BRAIN
20:22	gdev	your braine on drugs
20:24	tomoj	holy crap, pst takes a depth
20:26	tomoj	now I can stop lein-swanking instead of jacking-in just to be able to see .printStackTrace