#clojure – 2017-01-05

2017-01-05

10:44	smandy	hi all, has anyone got a simple example of embedding nrepl into an existing app so I can poke at it from cider in emacs?
10:44	smandy	the examples I find are mostly clojure examples. I'd like to see a java one...
10:45	dysfun	there are mostly just gists floating around on github i think
10:46	smandy	dysfun: thanks - found one.
10:46	dysfun	clojure is super easy to embed, so you have the option of just using the snippet on the "java interop" page and adapting it
10:48	smandy	dysfun: yeah what I'm doing not working. Does clojur eneed to have a runtime booted up or something?
10:50	dysfun	it needs to be included as a dependency in your build
10:51	dysfun	org.clojure/clojure
10:51	dysfun	(e.g. 1.8.0 )
10:51	smandy	dysfun: I've got that far. Cider seems to connect then immediately disconnect. Neither party reporting anything too helpful :-(
10:52	dysfun	lovely
10:52	smandy	Hmm.. in messages cider claims 'Establishing SSH tunelled connection' Not sure if that's what I wanted... (using cider-connect).
10:52	dysfun	ssh tunnelled?
10:53	dysfun	how are you connecting to nrepl from cider?
10:54	smandy	cider-conect then answering host/port questions...
10:54	sobel	my brief experience adding clojure to a java project: i think i saved myself some trouble by deploying an uberjar to a local maven repo, so all the clojure-side deps got managed by lein
10:55	sobel	then i simply added a dep on that uberjar from my java app, regular maven style (hacking pom.xml)
10:55	dysfun	can't maven recursively add deps?
10:55	sobel	of course it can
10:56	sobel	the thing was letting lein indicate all my clojure deps in the ubjerjar and maven resolves those recursively from the java app side
10:57	sobel	point being, i gotta list the deps in project.clj, deploying an ubjerjar automates those into my java app via 1 dep
10:58	sobel	maintaining similar lein deps in pom.xml seems error-prone. i like the automation for progmatically squeezing out a class of build error.
11:13	osfabibisi	it has a list of what look like environment variables
11:13	osfabibisi	but aren't
11:13	osfabibisi	it would actually be Really Convenient to have boot set some environment variables for us in development ...
11:14	osfabibisi	e.g. so that we can run 'boot test' and 'boot run' locally, instead of 'some-locally-hacked-together-boot-wrapper test'
11:30	dysfun	osfabibisi: however the properties do share the name of environment variables
11:31	dysfun	but no, they're java properties in a properties file
11:31	osfabibisi	we're doing that part of 12-factor
11:31	osfabibisi	so much of our config is in environment (via baked AWS config, or consul or whatever)
11:31	osfabibisi	I don't understand java properties at all
11:32	osfabibisi	but certainly going to boot repl and typing (get-env) doesn't show me anything usefully like the result of (System/getenv)
11:42	sobel	really? aren't they a serialization of HashMap?
11:42	sobel	that you can access via the classpath
11:43	sobel	i always liked the pattern of hardcoded defaults -> props files -> env vars
11:43	sobel	(order of priority/fwd reference)
11:44	sobel	so props files might indicate env vars that could contain values that override defaults or props. for example.
11:51	osfabibisi	ah. I don't really know java, which doesn't help
11:51	osfabibisi	and when you search for e.g. "how do I get boot to set environment variables?" it doesn't help that it talks about "environment" and you don't know whether it means the OS ENV, or Java environemnt, or the "boot environment"
11:54	sobel	"the environment" generally means the actual OS-supplied environment variables. i've never heard it to mean props files. sometimes people point to props files with env vars or vice-versa but they are distinct in my experience
11:56	osfabibisi	ok... but in your build.boot, (set-env!) doesn't set an environment variable
11:57	sobel	i think that's an unfortunate overloading of "environment" in/by boot docs
12:12	dm3	osfabibisi: Boot has its own environment which you modify with `set-env!`/`merge-env!` and the likes. The system environment in Java/Clojure is accessed via `System/getenv`/`System/getProperties` and various other wrappers people have built around it (e.g. https://github.com/weavejester/environ)
12:14	osfabibisi	ah yes, "It works well for applications following the 12 Factor App pattern"
12:15	osfabibisi	I think we'd glanced at it briefly, and though it was better to use System/ for now
12:15	osfabibisi	but I'll have another look, ta dm3
12:18	sobel	12 factors sounds like a lot
12:19	technomancy	it signifies completion or perfection in jewish numerology
12:19	sobel	that's obnoxious of boot to overload "environment"
12:19	sobel	numerology has a place in s/w eng?
12:21	technomancy	software engineering is largely superstition anyway; might as well openly acknowledge it
12:21	sobel	...
12:22	technomancy	"I heard node.js is really good at scaling because it has async."
12:22	osfabibisi	I hear it's web scale
12:22	osfabibisi	and real-time
12:24	jmasseo	i liek empiricism in my software
12:25	osfabibisi	imperialist swine!
12:28	deadghost_	webscale non-blocking scrum enterprise waterfall
12:30	deadghost_	make sure to spin your laptop around 3 times before running your tests
12:30	MJB47	hands up who has a rubber duck on their desk
12:31	TMA	those are immensely hard to come by
12:31	osfabibisi	if they're hard, the rubber has probably degraded
12:31	TMA	not cool enough for the toy stores to stock them, not enough geek stores around
12:34	hiredman	clojurebot: hiredman is a rubber duck
14:00	justin_smith	TMA: your city and mine are different
14:28	dysfun	oops, i appear to be drunk and in charge of clojurescript
14:29	justin_smith	dysfun: this day in history, 1998: "oops, I appear to be sniffing glue and in charge of PHP"
14:30	dysfun	no dude, my descent into depravity isn't for another decade yet (i hope!)
15:12	tdammers	justin_smith: sadly, not much has changed, except the amount of glue
15:14	ragepandemic	Is there a recommended way of dealing with uniqueness validation spanning multiple columns in the luminus stack? I haven't really found any info in bouncer
15:14	tolstoy	Does :pre / :post go before the docstring, or after?
15:14	tolstoy	After params, before docstring?
15:15	amalloy	tolstoy: everything after the params is function body
15:15	tolstoy	Where is this documented?
15:15	amalloy	there is no such place as "after params, before docstring", because the docstring goes before the params
15:15	amalloy	(doc defn)
15:15	clojurebot	"([name doc-string? attr-map? [params] prepost-map? ...] [name doc-string? attr-map? ([params] prepost-map? body) + ...]); Same as (def name (fn [params* ] exprs)) or (def name (fn ([params ] exprs*)+)) with any doc-string or attrs added to the var metadata. prepost-map defines a map with optional keys :pre and :post that contain collections of pre or post conditions."
15:15	tolstoy	Oh, right.
15:16	amalloy	really, you put prepost-map after params?
15:16	amalloy	it this a dang joke?
15:16	tolstoy	And there I was wandering around in special-forms.
15:16	amalloy	i guess it makes sense because the preconditions depend on params
15:16	tolstoy	Yeah.
15:16	tolstoy	(defn name doc-string? attr-map? [params*] prepost-map? body)
15:17	amalloy	kinda funny though that if you want to define a function that returns a precondition map (eg for use in a macro) you'd have to wrap it in (do {:pre ...})
15:20	tolstoy	I've seen new folks put the doc string after the params and ... it doesn't error out. ;)
15:21	ragepandemic	I have these DB constraints https://www.refheap.com/124505 and I haven't really found a "nice" way of dealing with them (E.g. django which throws a validation exception). I could always do an explicit query for title, artist and album, but that doesn't feel like a nice way of doing it
15:23	kwladyka	(s/def ::weight (s/and number? pos?)) -> generate Infinity - is it something new for clojure spec? i didn't notice it before.
15:23	kwladyka	i really don't want such value, how to remove it?
15:24	ridcully	,(Double/POSITIVE_INFINITY)
15:24	clojurebot	Infinity
15:25	kwladyka	ok but how to prevent clojure spec to generate this value?
15:26	kwladyka	oh probably i should add something like int? there
15:26	luma	by changing the spec so that infinity isn't a valid value
15:26	kwladyka	hmm i didn't notice it before...
15:26	amalloy	"new folks". i do it myself all the time, tolstoy. aside: one good reason to run a linter
15:28	kwladyka	sorry, my fault
15:28	osfameron	what's a good clojure linter?
15:28	ragepandemic	amalloy, are there any linters?
15:29	ridcully	1.9 would fail to compile, right?
15:29	ridcully	atleast there is a spec for defn
15:29	amalloy	eastwood
15:29	luma	there's eastwood
15:31	technomancy	https://p.hagelb.org/clap.gif
15:31	technomancy	I. Just. Got. That.
15:32	technomancy	now I know how those people who get the Leiningen reference after using it for three years feel like I guess
15:32	ragepandemic	nice, thanks
15:33	ragepandemic	technomancy, can you explain, just incase there's people here that don't know... haha
15:33	osfameron	the Leiningen one probably requires you to aware of the obscure children's book doesn't it?
15:33	technomancy	it's not a children's book, but sure; it's obscure
15:34	technomancy	https://en.wikipedia.org/wiki/Leiningen_Versus_the_Ants
15:34	osfameron	leiningen is a terrible name, but at least it's googlable. boot one-upped them on that front...
15:34	technomancy	on the other hand it did get made into a film with Charleton Heston
15:34	ridcully	theres a movie?
15:34	technomancy	https://en.wikipedia.org/wiki/The_Naked_Jungle
15:35	ragepandemic	well, TIL
15:35	ragepandemic	thanks
15:35	technomancy	...any time?
15:35	osfameron	hmm, I wonder why I thought it was a kids' book, nvm
15:36	ridcully	that sounds awesome
16:08	Frozenlock	osfameron: because once upon a time kids stories were full of violence and dire consequences.
16:09	osfameron	just like the Tiger Who Came To Tea!
16:13	Frozenlock	I was thinking a little older. Like this one https://en.wikipedia.org/wiki/Pied_Piper_of_Hamelin
16:14	ragepandemic	does compojure-api support spec by any chance?
16:14	osfameron	woo, ooo, another thing that a linter might have caught... boils down to e.g. (defn foo [a] + a a)
16:14	osfameron	what does that actually do?
16:15	osfameron	oh, because you can have any number of forms in a function, and those forms can be atoms
16:15	osfameron	they're just helpfully ignored (except the last)?
16:32	amalloy	osfameron: (a) "atom" is a different thing in clojure; (b) they're evaluated for side effects, not ignored
16:35	scriptor	hm
16:35	scriptor	is there any tway that just referencing a var could cause a side effect?
16:36	amalloy	well if the var doesn't exist, you will get the side effect of an exception being thrown
16:37	amalloy	at compile time, i guess
16:43	justin_smith	if you expand from vars to classes, there are definitely classes that do weird things when referenced (even if you don't do anything to them)
16:44	amalloy	well. when referenced for the first time
16:44	amalloy	loading them isn't really the same thing as referencing them at all
16:47	timvisher	i desire a positional data structure that is indexed by a string, such that index-of is constant time.
16:48	timvisher	so (index-of ["foo" "bar" "bat"] "bar") => 1 or whatever
16:49	timvisher	rather than using, say, a hash-map with values as the position
16:49	timvisher	i feel like this must already exist
16:49	amalloy	constant time lookup by an arbitrary string? i feel like this not only doesn't already exist but is impossible
16:50	amalloy	log(n) is easy
16:50	TEttinger	yeah, constant time is probably right out because keys require some amount of time to hash, longer for longer strings
16:50	technomancy	constant time is also somewhat at odds with special relativity
16:51	timvisher	hmm… am i using the wrong term?
16:51	TEttinger	oh you
16:51	technomancy	TEttinger: =D
16:51	TEttinger	O(1) is constant time, sorta
16:51	timvisher	aren't key lookups in hash-maps considered 'constant time'?
16:51	TEttinger	strictly speaking, no
16:51	timvisher	ah
16:52	TEttinger	they're O(something related to k)
16:52	TEttinger	where k is the key size
16:52	TEttinger	not sure if it's log(k) or k
16:52	timvisher	well then i guess what i mean is that i want a data structure that i can dump stuff into, and then use the stuff dumped into it to lookup what order i dumped it in as
16:52	timvisher	that has something like the performance of a hash map :)
16:53	TEttinger	you may want ordered collections,which are a clojure lib called... ordered
16:53	TEttinger	in flatland
16:53	TEttinger	those don't, as far as I recall, allow you to get what ordering position an item is at
16:53	amalloy	they also assume items in the coll are unique
16:54	timvisher	the items i'm dealing with are unique
16:54	TEttinger	but it's trivial to use two collections here, one a map of strings to ints (assigned sequentially) , and one a vector of strings
16:55	amalloy	"trivial" unless you ever want to remove items
16:55	timvisher	i'm mapping a string to a priority, and i was hoping to avoid the monkey work of manually writing out the ordering
16:55	TEttinger	(it gets less trivial if it changes, yeah)
16:55	timvisher	and yes, making it easier to edit
16:55	timvisher	whatever :)
16:55	TEttinger	immutable, though, amalloy :)
16:55	amalloy	what does immutable have to do with it. disj and pop exist
16:56	amalloy	and dissoc
16:56	timvisher	but yeah i guess this is less common then i thought it would be :)
16:57	TEttinger	amalloy: I was being somewhat snarky about how clojure data doesn't change after creation
16:57	amalloy	timvisher: if you can reframe your problem to generate a lazy seq of all insertions you need to do up-front, then you can just wrote (zipmap insertions (range))
16:57	timvisher	amalloy: right. i can play with it like that. just figured this would be a standard data structure that i hadn't heard of before :)
16:58	timvisher	there is of course .indexOf on a vector but that's not anything like a hash-map lookup
16:58	timvisher	but honestly what i'm playing with right now is so small it's not going to matter
17:08	technomancy	psa: seattle clojure group is this evening
17:09	justin_smith	so is portland clojure group
17:09	justin_smith	sorry, you have to pick one, can't be at both
17:09	jeaye	What about SF Clojure group, if there's such a thing? :)
17:20	justin_smith	things not to do: debug code with the cache layer in front of it still turned on
17:55	ryan123	What books do you all recommend for a Clojure beginner? I got half way though "living clojure" and "clojure for the brave and true" and didn't like them much. I like books that have me writing code and thinking as I learn, not just copying code line by line from the book to see what it does... I really like the K&R C book.. show me a few key thing
17:55	ryan123	and have me write code and try to solve small problems...
17:56	tolstoy-	Maybe you don't need a book at all?
17:56	tolstoy-	Just start up a project, then ask Google?
17:57	ridcully	or go for one of the code challenge sites out there (e.g. 4clojure)
17:58	tolstoy-	I tend to want to learn, first, how to query a database or set up a quick webservice before I get interested in partition or group-by or whatever, so I'm guessing it depends on how you learn.
17:58	ryan123	Good suggestions.. I do like learning from a book first though... or along side something like 4clojure.
17:59	ryan123	Has anyone read "professional clojure" or the o'reilly "clojure programming" books?
18:17	technomancy	the oreilly one is great
18:29	devn	long live clojure irc
18:53	justin_smith	professional clojure is very good too
18:54	justin_smith	it has a bunch of stuff I had to learn by hanging out in IRC because it wasn't in books at the time
18:59	mikeyhc	https://www.tab.co.nz/racing/runner.html?date=2017-01-06&meetno=2&raceno=1&entryno=1
18:59	mikeyhc	whoops, ww
20:48	itissid	Does someone have access to clojure source Javadoc
20:48	itissid	Link pls..
20:53	om	itissid: they are on maven
20:59	itissid	om: https://mvnrepository.com/artifact/org.clojure/clojure/1.9.0-alpha14 ?
20:59	itissid	Thats just the jar. I wanted a browsable javadoc link though..
21:00	om	yeap
21:01	om	itissid: if you use Dash, you can import the jar and browse it there
21:02	om	itissid: but there are very few comments, you'd be better off reading the source
23:27	marshzor	,(->> (range) (filter odd?) (map (+ 2)) (take 3))
23:27	clojurebot	#<ClassCastException java.lang.ClassCastException: java.lang.Long cannot be cast to clojure.lang.IFn>
23:34	justin_smith	marshzor: (+ 2) is 2
23:34	justin_smith	2 is not a function
23:34	justin_smith	,(+)
23:34	clojurebot	0
23:34	justin_smith	,(+ 2)
23:34	clojurebot	2
23:35	justin_smith	,(1 2 3)
23:35	clojurebot	#error {\n :cause "java.lang.Long cannot be cast to clojure.lang.IFn"\n :via\n [{:type java.lang.ClassCastException\n :message "java.lang.Long cannot be cast to clojure.lang.IFn"\n :at [sandbox$eval113 invokeStatic "NO_SOURCE_FILE" 0]}]\n :trace\n [[sandbox$eval113 invokeStatic "NO_SOURCE_FILE" 0]\n [sandbox$eval113 invoke "NO_SOURCE_FILE" -1]\n [clojure.lang.Compiler eval "Compiler.java" 69...
23:35	justin_smith	err
23:35	justin_smith	,(+ 1 2 3)
23:35	clojurebot	6
23:36	justin_smith	,(sequence (comp (filter odd?) (map #(+ 2 %)) (take 3)) (range))
23:36	clojurebot	(3 5 7)
23:36	justin_smith	(bonus transducer version)
23:43	marshzor	,(->> (range) (filter odd?) (map #(+ 2 %)) (take 3))
23:43	clojurebot	(3 5 7)
23:43	marshzor	is there a better way?
23:44	justin_smith	the transducer version avoids making three out of the four lazy seqs that the ->> version makes
23:45	justin_smith	the clojure compiler is not especially smart, and (take ... ( map ... (filter ... (range)))) makes four lazy seqs, and throws three of them away
23:45	technomancy	I just realized the l2l compiler tries to calculate transducers for nested map/filter stuff at compile time
23:45	technomancy	confused the hell out of me when I read the source
23:46	justin_smith	l2l?
23:46	technomancy	lisp->lua compiler
23:47	technomancy	https://github.com/meric/l2l/blob/master/l2l/ext/iterator.lisp#L73 completely unreadable imo
23:48	technomancy	but I asked him about it and I think the answer he gave was actually transducers even though he didn't use the term
23:48	cemerick	cfleming: defaulting to aligning comments to column 60? We need to have a talk. ;-P
23:48	technomancy	cemerick: so I hear you are looking for a keyboard
23:48	technomancy	and maybe a text editor?
23:48	technomancy	I can give you a 2 for one deal
23:48	cemerick	heh
23:49	cemerick	I think you're probably late on the latter
23:49	cemerick	I'd already been using intellij for java stuff, and cursive is the Real Deal™ at this point
23:50	cemerick	I spent a day with proto-repl and atom, and that would have been perfectly workable and a fun thing to contribute to (in my copious free time I guess?), but mmm that static analysis is sweet stuff.
23:50	technomancy	oh yeah I forgot Java is a thing
23:50	cemerick	nice burn
23:51	cemerick	technomancy: but I have the atreus page open right now
23:51	technomancy	I should mention in the salespitch that it's designed using lisp
23:51	cemerick	heh
23:52	cemerick	I really like it fundamentally, but the layers thing makes me think I'd never actually use it
23:52	technomancy	it takes some getting used to
23:52	technomancy	having a numpad is a lot nicer than digits across the top once you do IMO
23:54	cemerick	I'm more worried about cursor keys, I think?
23:54	technomancy	you have the cursor keys on the home row with fn
23:55	technomancy	if I was local to you I'd offer a loaner =)
23:56	cemerick	what do you do about left/right alt (for compose key, etc?)
23:57	technomancy	I don't do it personally but you can set fn+alt to right alt
23:57	cemerick	ok
23:57	cemerick	I dunno, this is almost foot-pedal-for-esc territory :-)
23:58	technomancy	yeah it's definitely optimized for emacs/vim users to be sure
23:58	cemerick	well, I plan on reviving my actual-vim use for non-clojure/java stuff, and ideavim is supposed to be good, so
23:59	cemerick	do you find that you're able to use regular keyboards still without too much pain?
23:59	technomancy	it's not bad unless I try to go back to qwerty
23:59	cemerick	oh, you're dvoraking?
23:59	technomancy	yup yup