#clojure – 2015-12-22

2015-12-22

00:29	allhailcaesar	Is there a way to make lein check already downloaded dependencies? I'm on a bad connection, and am worried I might be seeing some errors in a project due to connection instability.
01:07	chomwitt	good morning.
01:08	chomwitt	a newbie question. where is ring.core ?
01:13	allhailcaesar	@chomwitt are you getting an error that you don't have it?
01:15	chomwitt	no. i'm trying to understand some basic things. http://ring-clojure.github.io/ring/ i dont see any ring.core in tha API
01:15	allhailcaesar	adding [ring/ring-core "1.4.0] to your dependencies will pull it to your classpath
01:16	hiredman	the docs show namespaces, and there is no ring.core namespace, so it is not in the docs
01:17	hiredman	but there is a maven artifact (a jar) with the group-id `ring` and the artifact-id `ring-core`
01:18	hiredman	namespaces and maven coordinates are orthogonal, and can be completely different, but many projects have maven coordinates that are similar to their namespaces
01:19	chomwitt	what the diff of including in my project.clj [ring "1.4.0"]] and [[ring/ring-core "..."]]
01:19	chomwitt	?
01:19	hiredman	the ring artifact will bring in ring-core and some other stuff as dependencies
01:19	chomwitt	hiredman: your explanation i think is some levels above me :-)
01:20	chomwitt	i dont have an idea what a maven artifact is
01:20	hiredman	what goes in your project.clj are maven coordinates for dependencies (lein grabs stuff from maven repos)
01:20	hiredman	chomwitt: basically a jar
01:20	chomwitt	better :-)
01:20	chomwitt	a jar brings some bells :-)
01:21	hiredman	a zip file full of code
01:21	hiredman	when you see `foo/bar` in project.clj `foo` is what maven calls the group id and `bar` is what maven calls the artifact id
01:22	chomwitt	so why some tutorials use ring/ring.core and others just ring ?
01:22	hiredman	if you have something like `ring` lein assumes the group id and the artifact id are the same, so `ring` is the same as `ring/ring`
01:22	chomwitt	hiredman: i see. makes sense nwo
01:22	chomwitt	now
01:23	allhailcaesar	chomwitt: This might help you with the practical side of your question, http://kendru.github.io/restful-clojure/2014/02/19/getting-a-web-server-up-and-running-with-compojure-restful-clojure-part-2/
01:24	hiredman	the ring project used to be published as a single ring artifact, but it is now published as a finer grained set of libraries, you can still get everything by depending on `ring`, but you can also depend on smaller parts of ring, like `ring/ring-core`
01:24	hiredman	so for tutorials they are likely interchangable
02:54	keep_learning	Hello everyone
02:54	keep_learning	I am trying to extract the information https://www.refheap.com/112992
02:55	keep_learning	when I am using (map (comp :href :attrs) (list-of-element)) then it return all the links
02:55	keep_learning	but I want to extract the :content also
02:56	keep_learning	so I have written (map :content (list-of-element)) gives me list of list of one element
02:56	keep_learning	I tried to combined it together
02:57	keep_learning	(map (fn [x] ( (comp :href :attrs) x, :content x)) (list-of-element))
02:57	keep_learning	but getting error
03:04	Kneiva	keep_learning: (Without looking at the paste): That last anonymous function could be something like (juxt (comp :href :attrs) :context)
03:06	keep_learning	Kneiva, Thank you
03:09	Kneiva	uh, :content instead of :context
05:29	keep_learning	https://www.refheap.com/112993
05:29	keep_learning	Hello everyone.
05:29	keep_learning	I have list of url links
05:30	keep_learning	and I want to navigate through all these links sequentially
05:30	keep_learning	so I can't write (map fetch-page-from-link url-links)
05:30	keep_learning	I want to do it sequential manner
05:34	kungi	keep_learning: does fetch-page-from-link have sideeffects? If yes then `doseq` is right for you.
05:35	keep_learning	(defn fetch-page-from-url
05:35	keep_learning	"fetch page source/html page from given url"
05:35	keep_learning	[url]
05:35	keep_learning	(do
05:35	keep_learning	(t/set-driver! {:browser :firefox}) ;set this for moment
05:35	keep_learning	(t/get-url url)
05:35	keep_learning	(t/page-source)))
05:35	keep_learning	kungi, Yes but it returns page of url
05:35	kungi	returning something is not a sideeffect. But set-driver! probably is.
05:35	keep_learning	I have to process that html page
05:36	kungi	keep_learning: why are you using `do` here?
05:36	keep_learning	and (t/get-url url) is also a side effect
05:36	kungi	probably yes
05:36	keep_learning	kungi, For sequential execution
05:36	kungi	keep_learning: defn and fn also do an "implicit do"
05:37	keep_learning	kungi, Thank you
05:37	keep_learning	so I can write (map fetch-page-from-url url-link) ?
05:38	kungi	keep_learning: as far as I see it yes.
05:38	keep_learning	Thank you
05:38	kungi	keep_learning: hmm ok wait. Maybe lazyness will screw you there
05:38	kungi	keep_learning: I would use `doseq`
05:51	owlbird	how to generate q SQL according different parameter pairs. for example, parameters name and department both are optional, (department maybe used to join another table), what the best way to handle this? Do I have to write a long long (cond ..) ?
06:03	Kneiva	owlbird: I'm not sure I understood the question right. But how about giving parameters in a map and render the SQL from its entries?
06:03	Kneiva	,(clojure.string/join " AND " (map (fn [[k v]] (str (name k) "=" v)) {:id 12 :name "aa"}))
06:03	clojurebot	"id=12 AND name=aa"
06:05	Kneiva	And I would think there is some library that can do this kind of thing for you.
06:10	owlbird	select * from user u (if department != "") join dept d on u.dept = d.dept and d.name=? (if name != "") where u.name=?
06:11	owlbird	department/name both are optional parameter, which would be treated like a SQL segment switch, to open/close a logical.
06:20	Kneiva	owlbird: search for sql abstraction here: http://www.clojure-toolbox.com/
06:25	ridcully	banging strings together has a good chance to introduce sql injections - so watch out here
06:26	keep_learning	Hello everyone
06:26	keep_learning	I have clojure file and want to covert it to jar file
06:27	keep_learning	https://www.refheap.com/112994
06:42	keep_learning	Do I need to add main in clojure file
06:44	Kneiva	If you want it to be runnable jar.
06:48	keep_learning	Kneiva, I want to call go-to-tripadv from other java file
06:49	powered	if you want to use the jar as a library then you don't need a main
06:50	keep_learning	powered, Thank you
06:51	keep_learning	I have run lein uberjar
06:51	keep_learning	and it generated the jar in target directory
06:53	powered	you can also run lein jar if you don't want to include dependencies
06:58	keep_learning	I am getting two jar files
06:58	keep_learning	tripadvisor-0.1.0-SNAPSHOT.jar
06:58	keep_learning	tripadvisor-0.1.0-SNAPSHOT-standalone.jar
06:59	keep_learning	Which one I should add to java project to fetch go-to-tripadv function
06:59	keep_learning	?
07:06	Kneiva	keep_learning: standalone has all the dependencies like Clojure, selenium and other things you use in your clojure code. If you do not have them on the classpath otherwise you should use the standalone jar.
07:08	keep_learning	Kneiva, I have added both the jar file
07:09	keep_learning	but having problem in calling the function go-to-tripadv
07:14	Kneiva	keep_learning: Maybe this helps: http://stackoverflow.com/a/23555959
08:57	vy	Hi all! I am looking at TechEmpower web framework benchmarks: https://www.techempower.com/benchmarks/ Can somebody enlighten me how on earth Compojure can beat Java servlets in the very same benchmarks, given the fact that Compojure depends on Ring, which depends on Java servlets. What am I missing?
09:05	hiredman	ring and servlets are both interfaces, not implementations, so neither of those things can actually be benchmarked
09:06	hiredman	the servlet api specifies how http can be represented as java method calls, ring specifies how http can be represented as clojure data structures
09:07	vy	hiredman: I agree, but I would expect Compojure to come after vanilla Java Sevlets, assuming that they are compared using identical servlet container configurations.
09:07	hiredman	an adapter exists that allows you to turn serlvet apis in to ring apis, but ring is a spec that doesn't depend on servlets
09:10	hiredman	the ring spec can be implemented (and has been) on other things besides servlets
09:10	hiredman	and compojure is built on top of ring
09:12	ridcully	since #1 and #3 seems to differ in db, i'd like to see, how compojure there would do with postgres
09:12	hiredman	so to benchmark "compojure" as a thing, without specificy compojure + what implementation of the ring spec, doesn't make sense
09:13	vy	hiredman: The code is available: https://github.com/TechEmpower/FrameworkBenchmarks/tree/master/frameworks/Clojure/compojure/hello
09:17	hiredman	vy: if you are comparing it to the servlet-raw numbers of techempower, (which is such a meaningless name, there is no such thing, the servlet api is an interface) then it looks like `servelet raw` is using some other servlet implementation, and whatever servlet implementation the compojure benchmark is using happens to be faster
09:17	vy	hiredman: Hrm... Thanks for the explanations.
09:19	hiredman	the techempower numbers are really neat, but non-trivial to interpret, and some of the ways the results are presented don't make much sense
09:20	vy	I think it is just yet another page for comparing apples and oranges. But that's my idea...
09:20	hiredman	alioth for http
09:21	vy	Alioth is measuring/benchmarking more comparable things.
09:23	hiredman	alioth is measuring performance of c ffi to libgmp
10:57	jcrossley3	little_lamb: cool nick, bro
10:58	little_lamb	jcrossley3: I did it JUST FOR YOU
10:58	jcrossley3	:)
12:20	aurelian	hello
12:20	aurelian	what's a nicer way of doing this: https://www.refheap.com/113004 ?
12:21	aurelian	I tend to solve most of this kind of problems with reduce/map/filter, but I feel there must be a better way
12:23	yenda	with specter maybe
12:23	yenda	(select [ALL :sources ALL] lolz)
12:23	ridcully	is the order important?
12:23	aurelian	nope, order is not important
12:24	aurelian	yenda -- will check that out thanks
12:25	ridcully	(into #{} (mapcat :sources lolz))
12:26	aurelian	oh, wow
12:27	aurelian	thanks
12:32	aurelian	and to keep it unique and as a vector is it better to apply distinct and use into [] or convert the result to vec?
12:33	justin_smith	I'd use ((comp vec distinct mapcat) :sources lolz)
12:34	aurelian	I'm very comfortable using reduce but somehow in clojure there's always a better / nicer way
12:36	mavbozo	,(doc mapcat)
12:36	clojurebot	"([f] [f & colls]); Returns the result of applying concat to the result of applying map to f and colls. Thus function f should return a collection. Returns a transducer when no collections are provided"
12:36	mavbozo	,(doc distinct)
12:36	clojurebot	"([] [coll]); Returns a lazy sequence of the elements of coll with duplicates removed. Returns a stateful transducer when no collection is provided."
12:36	aurelian	yup, is exactly what I doing in that reduce
12:36	aurelian	mapcat I mean
12:36	mavbozo	ah, justin_smith's version uses transducers
12:37	mavbozo	,(doc vec)
12:37	clojurebot	"([coll]); Creates a new vector containing the contents of coll. Java arrays will be aliased and should not be modified."
12:38	justin_smith	mavbozo: it doesn't actually, but it could probably be converted to do so
12:39	mavbozo	justin_smith, oh, my mistake
12:39	aurelian	,(doc comp)
12:39	clojurebot	"([] [f] [f g] [f g & fs]); Takes a set of functions and returns a fn that is the composition of those fns. The returned fn takes a variable number of args, applies the rightmost of fns to the args, the next fn (right-to-left) to the result, etc."
12:40	justin_smith	,((comp vec distinct mapcat) :foo [{:foo [1 2 3]} {:foo [2 3 4]} {:foo [3 4 5]} {:bar [42]}])
12:40	clojurebot	[1 2 3 4 5]
12:41	aurelian	sweet, thanks
12:56	justin_smith	,(into [] (comp (mapcat :foo) (distinct)) [{:foo [1 2 3]} {:foo [2 3 4]} {:foo [3 4 5]} {:bar [42]}]) ; mavbozo - this is the transducing version
12:56	clojurebot	[1 2 3 4 5]
12:56	mavbozo	,(into [] (comp (mapcat :foo) (distinct)) [{:foo [1 2 3]} {:foo [2 3 4]} {:foo [3 4 5]} {:bar [42]}])
12:56	clojurebot	[1 2 3 4 5]
12:56	WorldsEndless	What is the syntax for :require :only in an ns statement? I don't seem to be having luck with (:require [ring.util.io :only [piped-input-stream]])
12:57	justin_smith	haha, mavbozo did you just come up with the same thing right when I did?
12:57	mavbozo	justin_smith, zing isn't it? LOL
12:57	justin_smith	WorldsEndless: I thought it was use / only and require / refer
12:58	WorldsEndless	justin_smith: I'm not managing to parse that sentence...
12:58	justin_smith	mavbozo: especially because I had to help a coworker with a couple of things before coming back and figuring that out, haha
12:58	justin_smith	WorldsEndless: (:use [foo :only [bar]]) (:require [foo :refer [bar]])
12:59	mavbozo	justin_smith, jinx
12:59	WorldsEndless	Ok; so no :only for refer in ns? (unlike refer http://clojuredocs.org/clojure.core/refer)
12:59	justin_smith	WorldsEndless: (doc use) mentions :only, (doc require) mentions :refer
13:00	WorldsEndless	Guess I'm confused by the first example from the refer clojuredoc page
13:00	mavbozo	justin_smith, hahaha, took me quite some time to realize that the (comp ...) order is reversed
13:00	justin_smith	OK, but the args of require aren't given directly to refer
13:01	WorldsEndless	Ah, I see. My mind was transposing "require" and "refer" ...
13:07	qsys	I get a ClassNotFoundException when I try to (:gen-class :extends [some.class]) using maven. I have something like (ns my.namespace (:import (some class)) (:gen-class :extends [some.class]))
13:08	qsys	and I'm using the com.theoryinpractis:clojure.maven.plugin:1.7.1 maven plugin
13:09	justin_smith	qsys: have you verified that the class you are trying to extend is on the classpath?
13:09	qsys	for some reason, the sme.class is not found (it is present in the maven depencies)
13:09	justin_smith	qsys: you shouldn't need to import, btw
13:09	qsys	so yeah, I would suppose if it's in the maven dependencies, it's in the classpath (but apparently, it's not :p)
13:10	justin_smith	qsys: I don't know maven so well, but is there a way to make maven dump the classpath it would use for a given command?
13:10	qsys	yes, I thought it wasn't needed in the import, but due to the class not found exception, I added it... so I'll remove it
13:10	qsys	hmm, I'll check for maven
13:11	justin_smith	qsys: import just changes whether package qualifiers are needed, it doesn't do any class loading magic
13:11	qsys	allright, makes sense...
13:15	qsys	not that much logging/debug info with maven. searching for classpath when running plugins.
13:15	justin_smith	qsys: what about looking at the command line args when starting a repl?
13:16	justin_smith	via ps or whatever
13:18	qsys	nothing much about classpaths - don't like that
13:20	justin_smith	qsys: what about 'mvn dependency:build-classpath'
13:22	justin_smith	qsys: when I run "ps x" it shows the full classpath as specified on the command line of any java command I have running
13:22	qsys	then I get the right classpaths - when I add some.class from Java, there's no problem.
13:23	qsys	yeah, but with 'ps -x', well, I'm not fast enough: I run maven and it's 'immediately' done before I can say 'ps -x' :)
13:23	justin_smith	qsys: which is why I suggested starting a repl (if needed commenting out the gen-class so the repl runs)
13:23	devth_afk	there's a problem i've never had: mvn being too fast :)
13:24	justin_smith	the repl should stay running until you tell it to stop
13:24	justin_smith	haha
13:24	qsys	ok... thx - lol
13:24	qsys	I'm a slow speaker :)
13:28	qsys	all mvn jobs from the plugin don't seem to add other mvn dependencies in the classpath... I'll check that plugin config again
13:30	slester	I struggled to get Cursive to actually run my Leiningen project. I ended up having to ragequit and just run things from the command line like I always do. :(
13:34	justin_smith	slester: that seems like it misses out on a bunch of the benefits of using cursive
13:35	j-pb	slester: resyncing with lein often helps
13:35	slester	yeah, I follow the instructions I found to import a project from leiningen but I couldn't figure out how to get Run to work properly
13:35	j-pb	the leiningen tab on the right
13:35	justin_smith	slester: did you see these docs? https://cursive-ide.com/userguide/leiningen.html
13:35	j-pb	and then the sync symbol
13:35	slester	justin_smith: that's the one I followed, yup :(
13:35	justin_smith	slester: at what step did it fail?
13:35	slester	I'll try again later, but whew. IDEA is just huge and complicated.
13:36	slester	I just couldn't get clicking Run to work is all
13:36	qsys	lein is another option... but it does take more steps to build - I'd rather have it done in maven
13:36	slester	maybe I didn't go into the right menu like the one j-pb suggested
13:36	j-pb	slester: to get run working you also need to configure a repl for example
13:36	slester	the REPL worked
13:37	justin_smith	qsys: lein is friendlier for clojure specific stuff though (like clojure.test / clojure specific linters / other clojure test frameworks / etc.)
13:37	j-pb	slester: what didn't then :)?
13:38	slester	I don't know how many ways I can say "the run button" :( but as I said, one of my first times using IDEA so I probably did something wrong
13:38	slester	but it was a lot less plug-and-play than I had imagined when people are tweeting about the release of the Cursive IDE for Clojure I guess
13:40	ridcully	left of the run/debug/chronos/... buttons is a dropdown. there you can "edit configurations"
13:41	j-pb	slester: no but what do you expect the run botton to do? for me a repl would be what I need
13:44	slester	lein run?
13:45	j-pb	hrm, tbh I never use that
13:46	j-pb	slester: you would probably have to set up a clojure application configuration in intellij then
13:46	j-pb	however
13:46	j-pb	I don't see a reason for running lein run
13:46	j-pb	in development mode you want a repl
13:46	j-pb	in deploy you want a jar
13:46	ridcully	me neither. but if i extrapolate from the other build tools, you can either run it once from the (right hand side) lein tab (it there is one) or you should be able to add a configuration with that lein <run> task?
13:47	slester	well, I am a newb so it's probable I'm doing it wrong
13:47	j-pb	slester: generally when developing in clojure you want to use the repl
13:47	j-pb	because it allows you to hotload code into your program while you develop it
13:50	slester	it seems like a big pain to get code in there
13:51	MJB47	most people have a function in their editor to send code to the repl
13:51	slester	like I have no idea how I'd use it effectively. I usually use the REPL to try out code
13:53	j-pb	slester: yeah but you can also call your main from there
13:54	j-pb	slester: and then you can reevaluate parts of the code while its running
13:54	slester	I guess I need to watch a video or read some more about it, then.
14:12	devth	anyone using spacemacs for clojure?
14:12	devth	https://github.com/syl20bnr/spacemacs
14:16	TimMc	"An Emacs distribution"
14:16	rhg135	how do you deal with state like open sockets in an evented design?
14:16	devth	i'm a heavy vim user but thinking about seeing if all my workflows could be ported to spacemacs.
14:17	rhg135	the kind you can't recreate
14:17	TimMc	Oh dear. Soon we will see a rant parallel to GNU+Linux where someone complains that Emacs is really just the kernel and that $FOO is the toolchain that matters.
14:17	justin_smith	TimMc: most of emacs is just RMS' .emacs
14:17	wink	TimMc: it's Emacs/Linux, not "Linux"
14:19	justin_smith	TimMc: oh, someone could pull an ubuntu, and make an "easy to use" emacs which randomly sends you to amazon.com
14:19	TimMc	justin_smith: Ha, so it has already happened.
14:20	justin_smith	TimMc: some of us still remember the huge Lucid/GNU emacs split (I was too young for the gosmacs / gnumacs split though)
14:21	TimMc	GNU+Emacs
14:21	TimMc	I didn't start with emacs until maybe 2010.
14:22	justin_smith	part of the motivation for inventing the GPL: https://en.wikipedia.org/wiki/Gosling_Emacs
14:23	devth	i'm of the opinion that something as core as $EDITOR should be used for near-life in order to approach maximum potential proficiency and familiarity. so switching is a big deal :) but i've only used vim since 2009, and this would still be "vim-nature".
14:25	justin_smith	devth: I used vi, then vim, then emacs (back when Viper was the best vi emulation mode available), after many years with emacs I started to get wrist pain so switched to evil (the best current vim emulation mode)
14:25	justin_smith	spacemacs is built on evil mode
14:25	devth	nice. right
14:26	devth	long term i think emacs is positioned to better support lang workflows. scala in emacs is pretty amazing. clojure in vim and emacs are probably nearly on-par.
14:26	devth	haskell in emacs is way better than vim from what i've gathered.
14:26	BRODUS	can anyone recommend a good resource to learn about core.async
14:27	justin_smith	BRODUS: have you walked through the official intro?
14:27	BRODUS	no, im reading the section on braveclojure, im finding its explanations lacking
14:27	qsys	gen-class again... something really weird: when I use (:gen-class :implements [some.Class]), it compiles, however, some.Class is a abstract class... so when I change it to (:gen-class :extends [some.Class])
14:28	qsys	I get an ClassNotFoundException
14:28	qsys	it's not a classpath issue, since it does compile with :implements
14:29	justin_smith	qsys: maybe this is related to how how abstract classes are implemented in the vm - there are a lot of things that are abstracted one way in java and another in the vm, and clojure as a rule uses the vm's version
14:29	qsys	am I missing something about :extends and abstract classes (clojure 1.7.0, by the way)
14:32	slester	is there a good place to learn about using the REPL to its maximum when developing?
14:37	devth	slester: some good stuff at http://thinkrelevance.com/blog/2013/06/04/clojure-workflow-reloaded
14:44	spieden	slester: here's my ~/.lein/profiles.clj https://gist.github.com/spieden/5af1b11cadceaeed83b9
14:44	spieden	slester: might be old versions -- haven't checked in a while
14:45	slester	devth: thanks!
14:45	slester	and spieden!
15:09	BRODUS	am i understanding this correctly? (doseq [i (range 10 100)] (go (>! c (blocking-io-function i)))) will create 90 blocking processes, each one put on a thread in my thread pool. Since there are only 6 threads(4 core machine), only 6 processes will be able to execute concurrently.
15:10	qsys	allright, so :extend in :gen-class doesn't expect a vector - makes sense, a class can only extend one other class (in Java/on the JVM). sometimes things can be a little subtle
15:10	justin_smith	BRODUS: core.async creates 42+(nprocs*2) threads for its pool
15:11	justin_smith	BRODUS: but yes, this would lock up all 50 threads, then use more as they are available
15:11	justin_smith	which is why clojure.core.async/thread exists - for when you are doing blocking IO in core.async
15:14	justin_smith	BRODUS: if you use async/thread, it will return a channel that you can consume, and your go block can properly park and not own a thread (go (>! c (<! (thread (blocking-io-function i)))))
15:15	justin_smith	*not own a core.async pool thread - of course it still owns a (mostly inactive, blocking on io) thread
15:15	benjyz1	hi. is it possible to name async channels?
15:15	benjyz1	I want to implement publish-subscribe to topics
15:18	justin_smith	benjyz1: core.async/pub takes a "topic function" - you create your value (probably via a hash-map) so that the topic can be looked up in it. core.async/sub takes a topic as an argument.
15:20	BRODUS	justin_smith: i get it, but whats the other kind of thread if its not a core.async pool thread
15:20	justin_smith	BRODUS: a thread
15:21	justin_smith	you can make as many as you want, until the OS stops letting java create more
15:22	justin_smith	BRODUS: thread pools are useful because they let you reuse threads, which is good for performance, but you can always just make a new thread unless the OS tells you otherwise
15:22	justin_smith	see also java.lang.Thread
15:23	BRODUS	justin_smith: why would you want to reuse a thread?
15:23	justin_smith	BRODUS: because it is expensive to make new ones
15:24	justin_smith	BRODUS: core.async/thread actually uses a cached thread pool so even it can reuse threads https://github.com/clojure/core.async/blob/a6dc01d2ebb692a39e923988b0853ff2bd1a431b/src/main/clojure/clojure/core/async.clj#L420 the definition of thread is a couple blocks down from the pool definition there
15:25	benjyz1	interesting. a bunch of async functions have been moved to transducers
15:26	rhg135	but still you are bound by how many the hardware can run at a time, no?
15:26	justin_smith	benjyz1: I think the experience of designing and implementing core.async was part of the motivation for making transducers - they realized how much work they were redoing in order to map / filter / etc. on channels
15:26	justin_smith	rhg135: well, in terms of how many can run, sure, but the question started with a thread that would be blocked for a long duration
15:27	justin_smith	and that's handled with kernel level context switches and interrupts, it doesn't block a hardware thread (or else your computer wouldn't be very usable)
15:27	rhg135	ah I see
15:27	benjyz1	what about message durability? for me the problem is that its far from trivial to wrap TCP semantics in several scenarios
15:28	benjyz1	Peer-to-Peer networks and security is generally hard to do with TCP
15:28	justin_smith	benjyz1: yeah, core.async isn't about TCP or durability
15:28	justin_smith	benjyz1: I thought you meant pub-sub in core.async
15:28	BRODUS	justin_smith: thanks for the help
15:28	justin_smith	BRODUS: np
15:29	benjyz1	yes. I mean pub-sub over the internet via async. I assume both sides run the JVM
15:29	justin_smith	benjyz1: core.async as part of implementing pub-sub over sockets is a whole other can of worms, and you're probably better off using kafka and maybe tying that to core.async on your end if you want to use core.async
15:29	justin_smith	benjyz1: core.async is not a networking tool
15:30	benjyz1	yes absolutely, it is a can of worms
15:31	benjyz1	its kind of reason I'm drawn to Clojure in the first place. doing TCP means in a sense each process can use any language
15:32	benjyz1	Scala has Akka, and there is a wrapper around it called Okku
15:42	spieden	i much prefer core.async/CSP over Akka/Actors
16:33	pilne	ok, clojure has me stumped
16:34	BRODUS	pilne: whatsup?
16:34	pilne	(for [i (range 1 10)] (print i)) is returnning: 123456789(nil nil nil nil nil nil nil nil nil)
16:34	pilne	in the REPL
16:34	MJB47	what do you want it to output?
16:35	pilne	the nils confuse me?
16:35	MJB47	for returns a lazy seq
16:35	BRODUS	the list of nils is the output of for
16:35	MJB47	of all the returned values
16:35	MJB47	print returns nil
16:35	MJB47	if you dont care about the return values
16:35	MJB47	use doseq
16:35	MJB47	or dotimes
16:35	pilne	ohhhhhhhhhhhhh
16:35	BRODUS	the numbers preceding are side effects of the operations within for
16:38	pilne	whereas the for literally returns nothing (nil) on its own
16:40	cfleming	slester: If you're still having problems with a lein project feel free to ping me if you'd like help
16:41	BRODUS	for returns a lazy sequence, each item in the sequence is going to the be result of (print i)
16:41	BRODUS	print will print a string but it returns nil
16:43	pilne	because every function has to return "something" to be considered a function?
16:43	BRODUS	no, print is a function
16:44	BRODUS	it just always returns nil
16:44	justin_smith	pilne: the only things in clojure that I know of that do not return something are System/exit and throw (for obvious reasons you never get a return value when calling either)
16:45	justin_smith	even using interop with java / jvm stuff, if nothing else you'll get a return value of nil
16:45	pilne	well, it might be a bit quirky (for someone like me), but at least it is consistent (:
16:46	MJB47	well
16:46	justin_smith	pilne: that's how a lot of things in clojure are - not what you might be used to, but probably more consistent than what you are used to
16:46	MJB47	its the basis of functional programming
16:47	pilne	clojure is my first real REPL experience other than haskell, which makes it obvious up-front (in all the tutorials i found) that since it the REPL is inside the IOMonad, it will be quirky. So this is a fun new experience overall for me
16:48	justin_smith	pilne: yeah, the whole lang of clojure is in "io" more or less - which means source files and the repl are more mutually consistent, but we also don't have the benefit of purity
16:48	justin_smith	with the exception of the rarely used io! macro
16:49	BRODUS	pilne, heres a function that will print your string and return the string you passed in (defn print-with-return [s] (do (print s) (identity s)))
16:49	justin_smith	pilne: but even in haskell print returns - it's just that you are less likely to get a list of units returned by list processing - you'd get a type error instead more likely
16:49	MJB47	you can use print-str
16:50	justin_smith	BRODUS: #(doto % print)
16:50	MJB47	https://clojuredocs.org/clojure.core/print-str
16:50	justin_smith	MJB47: that's not a printing function though
16:50	justin_smith	that's for getting what print would have printed, but as a string
16:50	MJB47	wut
16:50	MJB47	oh
16:50	MJB47	you are correct
16:50	MJB47	nvm me
16:50	ridcully	i like doto too. it injects easily into existing code
16:51	amalloy	justin_smith: well, map print xs :: [IO a], so you might well not get a type error until later
16:51	BRODUS	nice, haven't seen doto yet
16:51	amalloy	er, IO ()
16:51	justin_smith	amalloy: yeah, my haskell is still very weak
16:52	amalloy	i've been doing the advent of code exercises in haskell
16:52	amalloy	it's good practice
16:52	justin_smith	cool!
16:52	amalloy	https://github.com/amalloy/advent-of-code if you are interested
16:52	justin_smith	I'm going through bitemyapp's book (slowly)
16:52	justin_smith	cool, I'll need to check that out
16:53	pilne	my gf bought me bitemyapp's book for xmas, but i don't get the download key until xmas eve >.<
16:54	pilne	i was smart enough to not argue when she wanted to wear one of the outfits i got her for xmas yesterday though >.<
16:55	pilne	what can i say, i'm a functional programming junkie, i've even taken an interest in factor lol
17:00	tem0p	(second [123 1001])
17:00	tem0p	=> 1001
17:00	tem0p	(second [123 01001])
17:01	justin_smith	tem0p: 01001 means "1001 in octal"
17:01	justin_smith	,0xff
17:01	clojurebot	255
17:01	justin_smith	,010
17:01	clojurebot	8
17:01	tem0p	justin_smith: so what does that second statement return?
17:01	justin_smith	tem0p: I forget, but it's 1001 in octal
17:01	justin_smith	,01001
17:01	clojurebot	513
17:02	justin_smith	,8r1001
17:02	clojurebot	513
17:02	tem0p	justin_smith: Urgggh, so I'll have to change it to ["123" "01001"]?
17:02	justin_smith	tem0p: if you want it to print with a leading 0, use a format string
17:03	tem0p	justin_smith: Ahh good idea, thanks!
17:03	justin_smith	,(format "%05d" 1001)
17:03	clojurebot	"01001"
17:04	tem0p	justin_smith: I was testing with [513000 01001] and getting 513 back lol, so confusing.
17:04	justin_smith	ahh, yeah I can see how that would be confusing
17:07	TEttinger	tem0p: neat the starting zero for octal is an annoyance in many languages. however, clojure adds a new and interesting thing like starting 0 for base 8 or 0x for base 16...
17:08	TEttinger	,[2r001001]
17:08	clojurebot	[9]
17:08	TEttinger	,[3r001001 4r001001 5r001001 6r001001 7r001001]
17:08	clojurebot	[28 65 126 217 344]
17:08	TEttinger	,[13r001001 14r001001 15r001001 16r001001 17r001001]
17:08	clojurebot	[2198 2745 3376 4097 4914]
17:09	justin_smith	,36rjustinsmith
17:09	clojurebot	72595113320300741
17:09	TEttinger	and my absolute favorite is using 36r to encode arbitrary alnum strings as numbers, yes
17:09	tem0p	lol
17:09	TEttinger	,36rTETTINGER
17:09	clojurebot	82974197147859
17:10	justin_smith	,(> 36rjustinsmith 36rtettinger)
17:10	clojurebot	true
17:10	justin_smith	:P
17:10	TEttinger	,(> 29rjustinsmith 35rTOMMYETTINGER)
17:10	clojurebot	#<NumberFormatException java.lang.NumberFormatException: For input string: "justi">
17:11	TEttinger	eh?
17:11	TEttinger	,(> 30rjustinsmith 35rTOMMYETTINGER)
17:11	clojurebot	#<NumberFormatException java.lang.NumberFormatException: For input string: "justi">
17:11	TEttinger	,(> 30rjustinsmith 35rTOMMYETTINGER)
17:11	clojurebot	#<NumberFormatException java.lang.NumberFormatException: For input string: "justi">
17:12	TEttinger	ohhh t
17:12	TEttinger	,(> 31rjustinsmith 35rTOMMYETTINGER)
17:12	clojurebot	false
17:12	TEttinger	wonder why it stopped at i not t
17:12	TEttinger	I thought you stuck a \ufeff in there
17:14	justin_smith	nah, the number formatter wouldn't even take that
17:15	wink	daily wtf
17:18	wink	suddenly my joke proposal for 0sqprFFXIV for roman numbers sounds sane.
17:18	wink	(different language though)
17:18	wink	and it's spqr of course
17:19	justin_smith	,(clojure.pprint/cl-format "wink: ~@r" 42)
17:19	clojurebot	#error {\n :cause "clojure.pprint"\n :via\n [{:type java.lang.ClassNotFoundException\n :message "clojure.pprint"\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$1 run "URLClassLoader.java" 355]\n [java.security.AccessController doPrivileged "AccessController.java" -2]\n [java.n...
17:19	justin_smith	,(require 'clojure.pprint)
17:19	clojurebot	nil
17:19	justin_smith	,(clojure.pprint/cl-format "wink: ~@r" 42)
17:19	clojurebot	#error {\n :cause "Don't know how to create ISeq from: java.lang.Long"\n :via\n [{:type java.lang.IllegalArgumentException\n :message "Don't know how to create ISeq from: java.lang.Long"\n :at [clojure.lang.RT seqFrom "RT.java" 535]}]\n :trace\n [[clojure.lang.RT seqFrom "RT.java" 535]\n [clojure.lang.RT seq "RT.java" 516]\n [clojure.core$seq__4116 invokeStatic "core.clj" 137]\n [clojure.co...
17:20	justin_smith	ergh
17:20	justin_smith	,(clojure.pprint/cl-format nil "wink: ~@r" 42)
17:20	clojurebot	"wink: XLII"
17:20	justin_smith	,(clojure.pprint/cl-format nil "wink: ~r" 42)
17:20	clojurebot	"wink: forty-two"
17:20	wink	not half as cool :P
17:20	justin_smith	haha
17:21	wink	still, wow
17:22	wink	I'm not sure I'd apply violence to a coworker using that example here though: https://clojuredocs.org/clojure.pprint/cl-format
17:22	wink	(cl-format true "There ~[are~;is~:;are~]~:* ~d result~:p: ~{~d~^, ~}~%"
17:23	wink	"oh sorry, my cat walked over the keyboard"
18:18	devth	,(def a 1)
18:18	clojurebot	#'sandbox/a
18:19	devth	when you def something in clojurebot how long does it last? does clojurebot auto-reset the sandbox on some interval?
18:19	devth	,help
18:19	clojurebot	#error {\n :cause "Unable to resolve symbol: help in this context"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.RuntimeException: Unable to resolve symbol: help in this context, compiling:(NO_SOURCE_PATH:0:0)"\n :at [clojure.lang.Compiler analyze "Compiler.java" 6704]}\n {:type java.lang.RuntimeException\n :message "Unable to resolve symbol: help in this co...
18:19	justin_smith	devth: yeah, I think it's around 5 minutes
18:19	devth	interesting
18:19	justin_smith	but it's not 5 minutes from when you made the def, it's just every 5 minutes
18:20	devth	yeah. so you could get erased mid-experiment :)
18:20	amalloy	well don't use def then
18:20	devth	would be cool if you could snapshot/save sessions
18:20	devth	mainly curious for my own bot's lang repls :)
18:24	justin_smith	~help
18:24	clojurebot	Nobody can help with "X doesn't work". Please provide context: what you did, what you hoped would happen, and what happened instead. A stack trace is especially helpful, if applicable.
18:25	justin_smith	well there's a nice domain error for me
18:25	amalloy	dang, that might be the most polite factoid i've written
18:30	spieden	bah, doesn't work with abstract classes
18:32	justin_smith	spieden: try proxy
18:32	justin_smith	unlike reify, proxy can do concrete inheritance
18:34	amalloy	abstract classes :(
18:34	spieden	cool thanks
18:34	spieden	yeah so gross =\
18:34	spieden	it only has one concrete method
19:19	devth	hm, started using protocols and now i have to `lein clean` all the time
19:20	devth	lots of weird error messages like "No single method: foo of interface ..."
19:21	justin_smith	devth: protocols and cached stuff / reloading don't really play nicely
19:21	devth	i'd expect a repl restart to fix things though
19:21	devth	and at first they did
19:21	justin_smith	devth: lein caches things
19:22	devth	k
19:22	devth	just can't quite figure out when i would have to clean
19:22	justin_smith	devth: iirc target/stale/
19:23	devth	rm -rf it to clear cache?
19:23	devth	mine has a single file: extract-native.dependencies
19:24	justin_smith	I mean this is what lein clean should be cleaning, is the whole target dir
19:24	devth	ah
19:26	devth	i don't know if my code is actually reloading at all. time for some (log/debug "WTF?")
19:28	devth	lol it was a shadowing problem
19:28	justin_smith	oops!
19:29	devth	while trying to debug another problem of a dynamically bound var being unexpectedly nil...
19:31	devth	hm. so if i pass a fn as a callback using #'myfn syntax, when myfn gets called, bindings are not persisted?
19:32	justin_smith	Calling #'myfn as a function always looks up the latest value of that var. If you are using something like tools.namespace the var might have been deleted from the namespace instead of mutated, but otherwise, with normal code reloading, the function calling the var should end up invoking the new value.
19:39	devth	hm. looks you're right.
19:39	devth	still i will remove #' and see what happens.
19:42	devth	do bindings cross ref boundaries?
19:43	devth	the irc lib is taking my callbacks and storing them in a ref
19:45	tem0p	is there a way to add multiple singular elements at once? so something like (<fname> v ({:a a :b b} {:c c :d d})) => [{:a a :b b} {:c c :d d}]
19:47	ridcully	apply conj?
19:47	justin_smith	,(apply conj [] '({:a a :b b} {:c c :d d}))
19:47	clojurebot	[{:a a, :b b} {:c c, :d d}]
19:47	justin_smith	,(into [] '({:a a :b b} {:c c :d d}))
19:47	clojurebot	[{:a a, :b b} {:c c, :d d}]
19:47	ridcully	there you have it from authority
19:47	justin_smith	into is just a beefed-up apply conj
19:47	tem0p	Ahh perfect, thanks :)
19:56	devth	this is what's going on: https://gist.github.com/devth/77067d61b7b0922bf6ec (Thread. ...) is being created in the irclj lib https://github.com/Raynes/irclj/blob/master/src/irclj/core.clj#L143
19:56	devth	bindings don't get copied into new Thread instances
19:57	devth	hmm. not sure how to fix since it's in the lib.
19:58	justin_smith	devth: if you use future instead of Thread it will propagate thread bindings
19:58	devth	hmm. maybe i will submit a PR
19:58	devth	Raynes: you around?
20:04	devth	justin_smith: yep that fixed it
20:05	justin_smith	devth: bonus, it also uses the expandable thread pool instead of one off thread creation
20:05	devth	ah cool
20:05	justin_smith	agent-send-off-pool is the one iirc
20:06	devth	https://github.com/Raynes/irclj/pull/35
20:06	devth	gotta go for now. thx for the help (again) justin_smith!
20:08	justin_smith	devth_afk: glad I could help
21:26	BRODUS	this is a really good video on core async https://www.youtube.com/watch?v=VrmfuuHW_6w
21:29	noncom\|2	i just found a super weird thing that kills (into {})
21:30	noncom\|2	,(into {} (partition 2 [:a 1]))
21:30	clojurebot	#error {\n :cause "clojure.lang.Keyword cannot be cast to java.util.Map$Entry"\n :via\n [{:type java.lang.ClassCastException\n :message "clojure.lang.Keyword cannot be cast to java.util.Map$Entry"\n :at [clojure.lang.ATransientMap conj "ATransientMap.java" 44]}]\n :trace\n [[clojure.lang.ATransientMap conj "ATransientMap.java" 44]\n [clojure.lang.ATransientMap conj "ATransientMap.java" 17]\n ...
21:30	noncom\|2	coz
21:30	noncom\|2	,(into {} '((:a 1)))
21:30	clojurebot	#error {\n :cause "clojure.lang.Keyword cannot be cast to java.util.Map$Entry"\n :via\n [{:type java.lang.ClassCastException\n :message "clojure.lang.Keyword cannot be cast to java.util.Map$Entry"\n :at [clojure.lang.ATransientMap conj "ATransientMap.java" 44]}]\n :trace\n [[clojure.lang.ATransientMap conj "ATransientMap.java" 44]\n [clojure.lang.ATransientMap conj "ATransientMap.java" 17]\n ...
21:30	noncom\|2	but
21:30	noncom\|2	,(into {} [[:a 1]])
21:30	clojurebot	{:a 1}
21:30	noncom\|2	wtf?
21:33	noncom\|2	is this the intended behavior?
21:35	BRODUS	looks like it, from the first example here: https://clojuredocs.org/clojure.core/into
21:35	justin_smith	,(vec {:a 1})
21:35	clojurebot	[[:a 1]]
21:35	justin_smith	noncom\|2: looks good to me!
21:36	justin_smith	,(into [] {:a 1})
21:36	clojurebot	[[:a 1]]
21:36	turbofail	,(conj {} [:a 1])
21:36	clojurebot	{:a 1}
21:36	justin_smith	(more direct comparison)
21:36	turbofail	,(conj {} '(:a 1))
21:36	clojurebot	#error {\n :cause "clojure.lang.Keyword cannot be cast to java.util.Map$Entry"\n :via\n [{:type java.lang.ClassCastException\n :message "clojure.lang.Keyword cannot be cast to java.util.Map$Entry"\n :at [clojure.lang.APersistentMap cons "APersistentMap.java" 42]}]\n :trace\n [[clojure.lang.APersistentMap cons "APersistentMap.java" 42]\n [clojure.lang.RT conj "RT.java" 645]\n [clojure.core$co...
21:36	noncom\|2	umm.. see, i get a list.. i want to (->> list (partition 2) (into {}))
21:37	justin_smith	noncom\|2: (map vec)
21:37	turbofail	just add a (map vec) after the partition
21:37	noncom\|2	oh
21:37	turbofail	basically, conj on a map knows what to do when it sees a vector, but not a sequence
21:37	noncom\|2	very strange really
21:38	noncom\|2	it could as well understand a two-element (), just like a two-element []
21:38	noncom\|2	can't imagine why shouldn't it
21:38	justin_smith	noncom\|2: but you can make a map entry out of a vector directly, you can't make one out of a list directly
21:38	noncom\|2	esp that most functions return ()s
21:38	noncom\|2	justin_smith: yeah, turns out so
21:39	noncom\|2	it's just that that is counter-intuitive
21:39	noncom\|2	is there any real reason for that?
21:39	noncom\|2	some greater good?
21:39	justin_smith	noncom\|2: I meant that literally - thecode that make a map entry can use a vector to make a map entry, a list would need converting
21:40	justin_smith	noncom\|2: so nobody made the converting default
21:40	noncom\|2	aha, that's what
21:40	noncom\|2	i see
21:40	justin_smith	noncom\|2: like it or not, clojure avoids building some conveniences that would have larger hidden costs
21:41	justin_smith	whether "larger" follows any reasonable standard of measure is another question :)
21:41	noncom\|2	well, yes, that makes sense. but in this particular case and with this particular error message it just an unexpected startling stumble
21:42	noncom\|2	good that you are here, guys, and can explain
21:42	BRODUS	is it that getting the two elements from the vector is faster than getting them from a list?
21:42	justin_smith	that's true - it's not something that can be caught statically when compiling, and often clojure messages that can't be caught while compiling are very odd
21:42	justin_smith	BRODUS: I'm not totally certain actually
21:44	turbofail	i feel like a performance-based reason is unlikely
21:45	turbofail	but who knows
21:45	justin_smith	turbofail: try submitting a patch that checks for non-vector sequentials and makes vectors automatically
21:45	justin_smith	turbofail: it will be rejected for performance reasons
21:46	justin_smith	turbofail: they reject patches that do sanity checks at runtime in order to have better failure messages - once again, performance reasons
21:50	turbofail	perhaps. but i feel like this particular thing could be implemented with basically no performance impact
21:50	justin_smith	do tell?
21:54	tem0p	is there a version of into that doesnt add duplicates for vectors? or do I just run (distinct col) over it after?
21:55	justin_smith	,(into [] (distinct) [1 2 3 3 4 5 1])
21:55	clojurebot	[1 2 3 4 5]
21:55	tem0p	ahhh, perfect, you're awesome, thanks
21:56	justin_smith	tem0p: the only thing is (distinct) won't check for items already in the vector
21:56	justin_smith	,(into [5] (distinct) [1 2 3 3 4 5 1])
21:56	clojurebot	[5 1 2 3 4 ...]
21:56	justin_smith	stupid cut off
21:56	justin_smith	,(into [2] (distinct) [1 2 3 3 4 5 1])
21:56	clojurebot	[2 1 2 3 4 ...]
21:56	tem0p	justin_smith: Oh right damn
21:57	tem0p	justin_smith: If i used a set then I could use union right?
21:57	justin_smith	tem0p: if you don't care about order
21:57	tem0p	justin_smith: yeah I dont mind order, that seems good then :) cheers
21:58	turbofail	hm, actually i see the real reason, looking at the code - it's because if it's not a vector, it assumes that what's coming in is going to be convertable to a sequence of map entries - e.g. another map
21:59	turbofail	,(into {} {:a 0 :b 1})
21:59	clojurebot	{:a 0, :b 1}
21:59	turbofail	so basically it's to make conj do what might be the right thing for map arguments
22:00	turbofail	and, i guess, any other sequences of MapEntries
22:01	turbofail	if it weren't for that you could totally remove the instanceof check for vectors, and just call clojure.lang.RT.nth to get the first and second args, and that'd be plenty fast for vectors
22:01	turbofail	(it'd still be slow for lists, but it wouldn't slow down the vector case)
22:03	turbofail	whoops, messed up my example
22:03	turbofail	,(conj {} {:a 0 :b 1})
22:03	clojurebot	{:a 0, :b 1}
22:36	justin_smith	,(conj :a {:b 2} {:c 3})
22:36	justin_smith	erm
22:36	clojurebot	#error {\n :cause "clojure.lang.Keyword cannot be cast to clojure.lang.IPersistentCollection"\n :via\n [{:type java.lang.ClassCastException\n :message "clojure.lang.Keyword cannot be cast to clojure.lang.IPersistentCollection"\n :at [clojure.core$conj__4104 invokeStatic "core.clj" 87]}]\n :trace\n [[clojure.core$conj__4104 invokeStatic "core.clj" 87]\n [clojure.core$conj__4104 doInvoke "core....
22:36	justin_smith	,(conj {} :a {:b 2} {:c 3})
22:36	clojurebot	#error {\n :cause "Don't know how to create ISeq from: clojure.lang.Keyword"\n :via\n [{:type java.lang.IllegalArgumentException\n :message "Don't know how to create ISeq from: clojure.lang.Keyword"\n :at [clojure.lang.RT seqFrom "RT.java" 535]}]\n :trace\n [[clojure.lang.RT seqFrom "RT.java" 535]\n [clojure.lang.RT seq "RT.java" 516]\n [clojure.lang.APersistentMap cons "APersistentMap.java"...
22:36	justin_smith	oh, right
22:36	justin_smith	,(conj {} [:a {:b 2}] {:c 3})
22:36	clojurebot	{:a {:b 2}, :c 3}