#clojure – 2016-01-15

2016-01-15

02:37	ulischinz	hey there
02:37	ulischinz	i
02:40	ulischinz	i'm trying to transform a vector of maps to a map of vectors, maybe someone can help me
02:40	ulischinz	given [{:a 1, :b 2, :c 3, :d 4, :e 5} {:a 9, :b 8, :c 7, :d 6, :e 5}]
02:40	ulischinz	i'd like to get {5 [{:a 1, :b 2, :c 3, :d 4, :e 5} {:a 9, :b 8, :c 7, :d 6, :e 5}]
02:42	ulischinz	i tried a lot but i cant manage... best result so far was a list of vectors :)
02:42	ulischinz	(for [p [{:a 1 :b 2 :c 3 :d 4, :e 5} {:a 9 :b 8 :c 7 :d 6 :e 5}]] [(:e p) p])
02:44	ulischinz	but thats not really what i want..
02:52	qsys	where's the 'p' comming from?
02:58	Kneiva	ulischinz: each map has an :e that you want to use as the key?
02:59	luma	(group-by :e maps)
03:06	ulischinz	sry tel...
03:08	ulischinz	now... @qsys i'd say that p is each element in that array...
03:08	ulischinz	Kneiva: exactly
03:09	ulischinz	luma: maps is ment to be the array of maps?
03:09	luma	yes
03:09	Kneiva	ulischinz: then what luma said above.
03:10	ulischinz	gonna check it out
03:10	Kneiva	,(group-by :e [{:a 1, :b 2, :c 3, :d 4, :e 5} {:a 9, :b 8, :c 7, :d 6, :e 5}])
03:10	clojurebot	{5 [{:a 1, :b 2, :c 3, :d 4, :e 5} {:a 9, :b 8, :c 7, :d 6, :e 5}]}
03:10	ulischinz	uhhhh how nice, thank you a lot
03:27	ulischinz	thanks again, its workig in my dev-environment with my production data...
03:30	Kneiva	(inc luma)
03:30	Kneiva	:/
03:33	yunfan	what do you guys recommend for using clojure developing website?
04:32	TEttinger	yunfan: depends what you want
04:33	TEttinger	a lot of people prefer to avoid using a stack of existing libraries that must be used together (ruby has this with rails, it has good and bad sides)
04:34	TEttinger	if you want a stack like that but a little more clojure-y, there's caribou
04:34	TEttinger	~caribou
04:34	clojurebot	Excuse me?
04:34	TEttinger	I think luminus is also a thing
04:35	TEttinger	otherwise, the various ring stuff may be what you're after, maybe look at how Om examples are hosted
04:35	yunfan	well i dont need rails like TEttinger
04:36	yunfan	it should be better to use a flask like one for me
04:36	TEttinger	http://www.clojure-toolbox.com/
04:50	qsys	yunfan: I usually use vert.x, which is not clojure. However, client-side I like clojurescript (rum) a lot, client side, I call clojure code from Java. vert.x just makes all kind of auth, communication, ... extremely easy. vert.x 2 could handle clojure. There's a clojure implementation on the way in vert.x 3, I hope :p.
04:50	qsys	... server side, I call clojure code from Java...
05:09	yunfan	qsys: thanks
08:31	neoncontrails	I think this is syntactically okay: (sql/db-do-commands "postgresql://localhost:5432/sandbox” (sql/create-table-ddl :testing [:data :text]))
08:32	neoncontrails	I got it from the Heroku Clojure/Postgresql quick start guide.
08:32	neoncontrails	But I'm getting the following error:
08:32	neoncontrails	BatchUpdateException Batch entry 0 CREATE TABLE testing (data text) was aborted. Call getNextException to see the cause. org.postgresql.jdbc2.AbstractJdbc2Statement$BatchResultHandler.handleError (AbstractJdbc2Statement.java:2762)
08:34	neoncontrails	How do I call getNextException? (and on what?) I found some solutions, but the wrapper they used is since deprecated.
08:34	justin_smith	neoncontrails: you get the exception object e, and call (.getNextException e)
08:35	justin_smith	you get that object by catching it, or in the repl, it will be bound to *e
08:36	neoncontrails	That asterick might be what was throwing me off. I'll try that
08:36	justin_smith	neoncontrails: *e is just the magic value in the repl
08:37	justin_smith	in real code you would do (try .... (catch BatchUpdateException e (println e) (println (.getNextException e)))) -- something like this
08:40	justin_smith	neoncontrails: also, I think the root issue is that db-do-commands does a transaction, and transactions and ddl don't mix
08:41	neoncontrails	justin_smith: weird. Let me make sure it's the same command I borrowed from Heroku
08:44	neoncontrails	Yeah, that's the same command as here: http://webcache.googleusercontent.com/search?q=cache:EOVSDgZ_WHgJ:https://devcenter.heroku.com/articles/clojure-web-application+&cd=1&hl=en&ct=clnk&gl=us (original seems to be down at the moment)
08:44	justin_smith	neoncontrails: https://clojure.github.io/java.jdbc/#clojure.java.jdbc/db-do-commands
08:46	justin_smith	neoncontrails: maybe ddl can be done in a transaction? anyway, getNextException will show you more info, if you catch the exception, log it, and then do the same with the nested exception
08:48	neoncontrails	Good idea. Thanks for telling me about *e, I had tried it the way and couldn't understand why it wasn't working
08:48	neoncontrails	*the other way
10:45	justin_smith	amalloy_: so did that compojure GET trick with runtime symbols work?
11:32	kungi	I am trying to compile an uberjar and keep getting "Method too large" errors from my compojure routes ...
11:33	kungi	Any Idea what I might be doing wrong?
11:33	tcrayford____	kungi: do you have lots of routes? Do they call lots of code?
11:34	justin_smith	kungi: put the body of the handler in a function, and call the function in the route
11:34	kungi	justin_smith: I do that everywhere.
11:34	justin_smith	unless the problem is having thousands of routes...
11:35	kungi	No not thousands. Less than 100.
11:35	justin_smith	kungi: are you using any macros like core.match or core.async inside the route definitions?
11:35	kungi	justin_smith: no
11:36	kungi	Firstly I wrapped all routes in a record to use them as components. Which worked fine.
11:36	kungi	I usually compile my application to an uberjar.
11:37	kungi	Then I added a small middleware function and the compilation started to fail.
11:37	justin_smith	maybe it would help to make sure you are not destructuring in the route definitions, and move the destrucuring into the individual handler functions
11:37	kungi	So I put all routes back into defroutes and eleminated the wrapping records etc...
11:37	justin_smith	or to split up the routes - you can define a set of routes as a handler
11:38	kungi	justin_smith: I did this. But it still fails.
11:39	kungi	I had the same problem a couple of days ago with my api routes (depending on compojure-api). I unwrapped them from their records and put them in compojure-api/defroutes* and it worked fine.
11:41	kungi	Somehow building an uberjar merges all the handlers together or ... something
11:43	ikitommi_	kungi: pre 1.0.0 compojure-api uses compile-time route resolution, which might cause that. With 1.0.0, the route tree is resolved at runtime. Should remove these issues
11:43	kungi	ikitommi_: there is a 1.0.0 compojure api?
11:44	kungi	I am using 0.24.4
11:44	ewilazarus	hey there guys. i need a little help with this function: http://pastebin.com/W3dDne9k - how could i break out of a for loop?
11:44	MJB47	you cant in clojure
11:44	luma	ewilazarus, for isn't a loop
11:44	MJB47	if you need to you can use loop recur, or reduce/reduced
11:45	luma	it's a list comprehension
11:45	MJB47	or just normal recursion
11:45	ikitommi_	kungi: soon, see https://github.com/metosin/compojure-api/blob/runtime-route-resolution/CHANGELOG.md#100-snapshot
11:45	luma	if you want a loop, use recursion or loop/recur
11:45	ewilazarus	ok, but in that case would i be able to break?
11:47	kungi	ikitommi_: I'll try compiling it with 1.0.0-SNAPSHOT
11:47	kungi	ikitommi_: 1.0.0. is not on clojars yet?
11:47	ikitommi_	kungi: not at clojars yet, will finalize things on weekend
11:48	justin_smith	ewilazarus: in a loop, all you need to do is not call recur, and it won't continue
11:48	lambda-11235	Are clojure's symbols the same as other lisps in that they have a comparison time of O(1)?
11:48	ikitommi_	need to write migration guide & make better error messages.
11:49	justin_smith	ewilazarus: if you use for, and generate a comprehension, it's lazy, so you can just top taking values from the list comprehension when you get "enough", whatever that means in your case
11:49	ewilazarus	justin_smith thanks
11:49	justin_smith	ewilazarus: also, the for list comprehension has a :while key where you can specify a condition that makes the results stop
11:49	justin_smith	but it's not a loop, it's generating a list
12:20	orz	Are there any software engineers here who might be willing to answer a few career-related questions from someone just starting out? I promise not to take up much of your time.
12:35	kungi	orz: sure
12:38	blake__	orz: Sure.
12:42	mpenet	ikitommi_: compojure-api looks sweet
12:43	mpenet	anyone cared to bench compojure routing ("clout") vs bidi for instance, I am curious?
12:58	blake__	I've got ClojureScript added into my Compojure project: Yay, me.
12:58	bitfx	affirmative :)
12:58	blake__	I created a clojure function called "log-message".
12:58	blake__	And I'm calling it from Compojure like: :onchange "cmart.core.log_message.call(null, 'Hello from Clojure!')"
12:59	bitfx	ahh, the exiting moments when trying out a new new language.
12:59	lokien	exiting :^)
13:00	blake__	Is that about how it goes? I know inside of cljs I can be all Clojure-y. But to talk from Compojure, I need the ugly Javascript?
13:01	blake__	Or is there some way to alias?
13:03	ridcully	blake__: just to have it asked: does this still work with :advanced compilation?
13:06	blake__	ridcully: Dunno, but thanks for asking. I wondered about name-mangling.
13:07	blake__	I'll have to check it out.
13:07	blake__	So what does one do?
13:11	blake__	Or am I the only one doing this? We either go big, all ClojureScript, or go home (to Javascript, shudder).
13:30	ikitommi_	mpnet: thanks ;) there is some bench at bidi readme https://github.com/juxt/bidi/blob/master/README.md#contributing
13:32	amalloy	justin_smith: yeah
13:33	amalloy	(apply routes (for [uri [...]] (GET [uri] ...)))
13:34	justin_smith	cool
13:34	justin_smith	I'm guessing that feature came after we did our own wacky solution
13:36	blake__	So, :advanced compilation doesn't seem to change anything, which makes me think I did it wrong.
13:36	blake__	But maybe it doesn't name mangle?
13:36	justin_smith	advanced should definitely be name mangling
13:38	amalloy	justin_smith: tbh i'm guessing that features has been there for a long long time. weavejester's stuff tends to support arbitrary inputs, and then additionally optimize for compile-time-known inputs
13:39	blake__	Maybe it's too simple a case.
13:39	amalloy	like how (html [:div foo]) compiles to like (str "<div>" foo "</div>"), but (let [tag :div] (html [tag foo])) still works, by analyzing the tag at runtime
13:45	blake__	OK, so I'm thinking the safe, clean way to do this is to export my clojurescript functions.
14:34	itruslove	scgilardi you're back!
14:48	TimMc	\o/
14:49	TimMc	Mr. Scenario C. Gilardi
14:51	amalloy	haha
15:17	lokien	how are you guys so quiet today? now I feel bad about that I'm procrastinating
15:18	lokien	not reading interesting irc stuff or anything
15:23	TEttinger	heh. I'm complaining about Firefox crashing constantly in #perl6 to someone I suspect may be a Mozilla fan
15:25	lokien	and you're.. a chromium fan?
15:25	kwladyka	is any nicer method to write ((first coll-f)) ? something like (run (first col-f)) or something less confuse?
15:27	TEttinger	lokien: if Firefox didn't crash for me and use hefty memory since an update several years ago, I would still be a firefox fan
15:27	lokien	TEttinger: several years ago and you're still mad at it? oh man
15:29	TEttinger	well I still need to open it occasionally
15:29	TEttinger	uptime: 54 milliseconds before crashing
15:30	lokien	aand you're on windows?
15:42	domgetter	I'm having trouble understanding namespaces. I'm trying to make a Luminus app, and when I'm in the repl, I can access myapp.views.index/html, but in the code in myapp.routes, I can't access that function unless I (ns myapp.routes (:require [myapp.views.index :refer :all]))
15:42	domgetter	Does the repl behave differently than my code does when I lein run it?
15:47	tdammers	depends how you start the repl, but yes
15:59	domgetter	Is there something like a let-ns which lets you do something in a namespace, but when the form ends, goes back to the previous namespace?
16:00	justin_smith	domgetter: wanting to write code in another ns is a symptom of a design problem, from what I have seen the solution is usually that you need another ns that accesses both of them
16:01	domgetter	justin_smith: I'll admit I may be doing something problematic. I'm trying to make a web framework that will be familiar to Rails developers.
16:02	domgetter	That is, this framework will be "opinionated"
16:03	justin_smith	well surely one can be opinionated without being wrong, and wanting to put code in another namespace is usually a sign you are doing it wrong
16:04	justin_smith	perhaps you need to inject a dependency, protocols are good for this
16:04	lokien	aren't our frameworks good enough though?
16:05	domgetter	lokien: Yes, I'm just trying to make something with the explicit goal of feeling familiar to Rails devs
16:06	domgetter	justin_smith: I'm trying to make it so that when a route is generated from, say {:get "/photos"}, a helper is available in the views for (photos-path) that makes a link to that route
16:07	justin_smith	domgetter: then I would create the namespace using create-ns and use intern to create the values, and make it clear that the ns is a runtime thing only and has no static file corresponding to it
16:07	justin_smith	it's still ugly, but at least that way it's possible
16:08	justin_smith	domgetter: also, consider that instead of an ns you could have a simple hashmap of keys to functions
16:08	justin_smith	especially since it would not be meant to map to any ns that actually exists
16:08	justin_smith	(as a file, that is)
16:19	domgetter	justin_smith: ah interning is the solution for which I was looking. I do promise to consider the hashmap with keys to functions solution.
16:20	justin_smith	domgetter: a pattern that has worked for me in the past is attaching keys to the request object, containing hash maps that the request handler can look in to find runtime resources, or custom handler functions that can't be provided at compile time
16:20	justin_smith	eg. a map that you can look in to find a cache of db results, or the current db config, or an asset pipeline the handler should invoke
16:24	hiredman	domgetter: you are not the first person to come from rails to want something like that, https://github.com/macourtney/Conjure comes to mind, but no one who uses clojure regularly seems to want that
16:47	domgetter	hiredman: Interesting. I like what they did with generators, but I think I have a pretty slick idea for routing. We'll see how it pans out
16:58	nanuko	anyone know why prismatic has moved to plumatic on github?
17:02	justin_smith	nanuko: google fu, the libs interfering with the result standing of their product?
17:03	justin_smith	nanuko: maybe this is a sign ... http://getprismatic.com/home
17:04	justin_smith	nanuko: "On December 20 2015 the company closed its consumer-facing apps and focuses on offering its machine learning algorithms to publishers and hedge funds.[5]" https://en.wikipedia.org/wiki/Prismatic_(app)
17:11	nanuko	justin_smith: yeah, after poking around a bit, i found an article http://venturebeat.com/2015/12/11/prismatic-is-shutting-down-its-news-app-for-ios-android-and-web-on-december-20/
17:42	princeso	justin_smith: are you into caribou man?
17:59	justin_smith	princeso: I am one of the caribou devs, but we haven't been working on it very actively lately
18:19	domgetter	How come + is available everywhere without requiring clojure.core?
18:20	domgetter	Is it possible to make something like that myself? Or would I have to modify Clojure itself?
18:20	domgetter	(I'm not saying I want to, I'm just trying to understand)
18:20	justin_smith	domgetter: the ns macro implicitly calls refer-clojure
18:20	justin_smith	which is basically (require '[clojure.core :refer :all])
18:21	justin_smith	domgetter: vinyasa has tools for doing similar stuff with your own stuff for dev
18:21	domgetter	ahh I see
18:29	WickedShell	Gotta be a stupid question: I'm porting some Java code to clojure and woking with interop i have a case where in java I would pass Rectangle.class what would the equivlent be in clojure?
18:30	amalloy	,String
18:30	justin_smith	Rectangle
18:30	clojurebot	java.lang.String
18:30	WickedShell	just pass it directly? well thats farrrr more convient
18:51	justin_smith	is it possible to request that clojure.data.xml be more lax about input? or perhaps there is anotherl lib that similarly does lazy sax based parsing and is flexible about input validity?
18:52	amalloy	justin_smith: tagsoup or a relative?
18:55	justin_smith	amalloy: the "lazy" option of clj-tagsoup is not actually lazy in terms of consuming the input, or even parsing.
18:56	justin_smith	amalloy: just fixed a thread leak in my app caused by the thread clj-tagsoup uses to generate elements never exiting if you don't fully consume the stream it creates
18:56	justin_smith	(doall x) - wow, 4000 threads is now 400 threads
18:56	amalloy	well, when you have a clojure library that wraps a java library badly, go to the source
18:57	justin_smith	right, right
18:57	amalloy	tagsoup alleges to expose a sax-like api
18:57	justin_smith	I spent a little time reading tagsoup, and ... yeah, I guess I know what's going to be giving me a headache this weekend :)
18:57	amalloy	but i can't easily find api docs
18:57	justin_smith	yeah, looks like I'
18:57	justin_smith	ll be making that wrapper
18:58	amalloy	well, "badly". arguably it wraps the java library in a way that is just at a different place on the convenience/correctness spectrum
19:00	justin_smith	right, right. I need specific features it wasn't providing.
19:01	justin_smith	but "create a thread that never exits unless you consume all the elements of this lazy seq" is a hell of a gotcha
19:02	amalloy	you'd be surprised how many people have created lazy seqs that assume you will fully consume them
19:05	hiredman	:(
20:25	oracle	how to split [1 2 3 5 6 7] into [1 3 6] [2 5 7]
20:25	oracle	split by position
20:27	justin_smith	,(apply map list (partition-all 2 [1 2 3 5 6 7]))
20:27	clojurebot	((1 3 6) (2 5 7))
20:27	justin_smith	,(apply map list (partition-all 3 [1 2 3 5 6 7]))
20:27	clojurebot	((1 5) (2 6) (3 7))
20:27	oracle	great, thx
20:31	ridcully	,(apply map list (partition-all 2 (range 7)))
20:31	clojurebot	((0 2 4 6))
20:33	justin_smith	,(apply map list (partition 2 (range 7)))
20:33	clojurebot	((0 2 4) (1 3 5))
20:33	justin_smith	aha! a case where partition is a bit better behaved than partition-all
20:36	TEttinger	,(take-nth [1 2 3 4 5 6 7] 2)
20:36	clojurebot	#<IllegalArgumentException java.lang.IllegalArgumentException: Don't know how to create ISeq from: java.lang.Long>
20:36	TEttinger	,(take-nth 2 [1 2 3 4 5 6 7])
20:36	clojurebot	(1 3 5 7)
20:36	TEttinger	oh there was no 4
20:39	ridcully	,(let [r (range 6)] (map (partial take-nth 2) [r (rest r)]))
20:39	clojurebot	((0 2 4) (1 3 5))
20:39	ridcully	,(let [r (range 7)] (map (partial take-nth 2) [r (rest r)]))
20:39	clojurebot	((0 2 4 6) (1 3 5))
20:47	pilne	i blew up my clojure >.<
20:48	pilne	although it actually might be leiningen
20:49	ridcully	errors?
20:50	pilne	installed lein per the website, then ran "lein" and then when i tried to run "lein repl" i get all sorts of java.security.* errors
20:53	justin_smith	pilne: what lein version?
20:53	pilne	2.5.3
20:54	justin_smith	os and java?
20:54	pilne	ubuntu 15.10 openjdk 1.8
20:54	pilne	64bit
20:54	justin_smith	hmm
20:55	pilne	i concur
20:56	pilne	lein run in a made project gives: Could not transfer artifact org.clojure:clojure:pom:1.7.0 from/to central (https://repo1.maven.org/maven2/): java.lang.RuntimeException: Unexpected error: java.security.InvalidAlgorithmParameterException: the trustAnchors parameter must be non-empty
20:58	justin_smith	pilne: http://stackoverflow.com/questions/4764611/java-security-invalidalgorithmparameterexception-the-trustanchors-parameter-mus
21:00	pilne	you the man
22:00	kenrestivo	i wonder how much time could be saved if IDEs had a "google" button that copied/pasted the error message into google
22:01	kenrestivo	i have to think that's the #1 debugging approach around. amazed it hasn't been automated yet
22:13	pilne	pretty sure it can be added to atom somehow, it has hoogle integration for haskell
22:40	amalloy	do people really google entire stacktraces?
22:40	TEttinger	yes.
22:40	TEttinger	me.
22:41	TimMc	"do people really google $FOO?" "yes"
22:41	TEttinger	normally you need to take some of it out
22:42	TEttinger	yeah amalloy, why are you asking that question? "do people really google twerking dogs?" might be more interesting
23:36	sdegutis	Is there a way to combine cond and let somehow?
23:37	sdegutis	I'd like to have a ton of conditions in the cond, and guard against bad values early on, and if they're good values, transform them and continue with the conditions.
23:37	sdegutis	I'm 99% certain it's not possible, but if it can be done, I'm 100% certain justin_smith would be the one to come up with the way :D
23:38	lambda-11235	sdegutis: You mean like if-let?
23:38	sdegutis	Kinda, but within cond, so I don't have to have another cond within a cond.
23:38	sdegutis	I've seen cond-let, but I'm pretty sure it's one-shot like if-let is.
23:39	sdegutis	I'm thinking more like (cond (nil? email) :error, bind 'user (get-user email), (nil? user) :error, ... )
23:39	sdegutis	Or something weird.
23:40	justin_smith	sdegutis: I assure you good sir, your high esteem of my knowledge in all things clojure is undeserved, and on this question I must disappoint you. I'd probably end up making some terrible concoction using delay and deref chains. There might be something like what you want hidden in the depths of flatland/useful though.
23:40	sdegutis	Haha
23:41	amalloy	nah, this massive let is not really a style we love. it exists, though, as egamble/let-else
23:42	sdegutis	Hmmm interesting.
23:43	sdegutis	But yeah, it's a bit gross.
23:43	sdegutis	I'll just have to get comfortable with nested conds.
23:43	sdegutis	Or an if-let at top.
23:43	sdegutis	Meh, nothing's perfect.
23:44	justin_smith	sdegutis: in all seriousness, in cases where I have complex logic that decides which bindings should be realized, I've found a let block full of delays, (some of which derefing other delays internally), combined with a cond block that decides which ones to deref given the runtime conditions works out OK
23:45	sdegutis	Hmm. Interesting idea.
23:46	amalloy	flatland/useful does have let-later, to manage that for you
23:47	sdegutis	Very neat.
23:55	sdegutis	Good night amalloy and justin_smith.