#clojure – 2015-11-03

2015-11-03

02:37	jeaye	How can I explode the result of a function call to the remaining arguments of another?
02:38	jeaye	(wants-three 1 (explode (gives-two)))
02:39	jeaye	Pulling it out into a let would be my first move, I just wonder if there's a library macro for this.
02:41	opqdonut	apply?
02:41	jeaye	Yup.
02:41	opqdonut	,(apply + 1 (concat [2 3] [4 5]))
02:41	jeaye	Just had found that apply can do it.
02:41	clojurebot	15
02:42	jeaye	Thanks.
02:48	jeaye	What's a good way of organizing helper functions in a namespace? foo.core has some helpers, foo.bar has some of its own, etc.
02:49	jeaye	In C++, it's common to have a `detail` or `impl` namespace per each namespace that has helpers.
02:59	jonathanj	is there a convenient way to do: (f (.foo o) (.bar o) (.baz o))?
03:00	jonathanj	since .foo is a reader macro (or something?) ((juxt .foo .bar .baz) o) won't work
03:48	TEttinger	jonathanj: there is memfn for turning java methods into fns
03:49	TEttinger	(doc memfn)
03:49	clojurebot	"([name & args]); Expands into code that creates a fn that expects to be passed an object and any args and calls the named instance method on the object passing the args. Use when you want to treat a Java method as a first-class fn. name may be type-hinted with the method receiver's type in order to avoid reflective calls."
03:49	tdammers	oh wow that looks super useful
03:53	jonathanj	that's useful, just not really so much here
03:55	tdammers	it kind of is, indirectly
03:55	tdammers	you can use memfn to wrap those methods, and then you can thread or compose them
03:56	tdammers	memfn creates actual clojure fns, so unlike the sugared java method calls, you can use those in threading macros without further ado
04:45	cfleming	I'm having a problem with lazy seqs and mutually recursive functions.
04:45	cfleming	I read on SO a post by amalloy saying that they were fundamentally incompatible, but I don't understand why.
04:46	cfleming	I have some code which looks like it should be ok, but blows the stack immediately, with what looks like an infinite loop.
04:46	cfleming	There isn't enough data for it to be the problem from Stuart Sierra's concat post.
04:48	Fender	do you have a link to the source code?
04:48	cfleming	I can refheap it, one sec
04:51	cfleming	Fender: https://www.refheap.com/111314
04:52	cfleming	It's basically a simple top-down parser for a simplified EDN, which should output a lazy sequence of formatting primitives (the {:op...} maps)
04:54	cfleming	The issue appears to be in map-entry, which uses lazy-cat to recursively generate the ops for a series of map entries
04:54	Fender	I don't fully understand what's going on in the top part but a nice way to get an SO over there would be to have #(expression lexer) always return something non-nil
04:55	Fender	you could rule that out by putting some (take 1000) in between
04:55	cfleming	Yeah, it's additionally tricky because the lexer is mutable
04:56	cfleming	I'll try just taking one element from the lexer instead of iterating at line 48
04:57	Fender	yes, you'll probably see by what the lexer generates where it's stuck
04:57	Fender	obviously peek is supposed to consume something in the mutable state there
04:57	cfleming	No, if I replace lines 48-50 with just (expression lexer) it still barfs, it's something in the mutually recursive functions.
04:58	cfleming	No, (peek) doesn't consume - (token) does.
05:00	Fender	is the stacktrace clear as to where it repeats?
05:00	Fender	alternatively you could println something at the entry of each fn
05:01	Fender	additionally, can you make sure that (token) consumes something? because idiomatically it could also be written as (token!)
05:01	cfleming	Yeah, I'm thinking that's what I'll have to do. The loop is RT.seq -> LazySeq.seq -> LazySeq.sval -> concat/cat/fn
05:02	Fender	from my limited understanding I suppose lazyseqs shouldnt be the problem because in the worst case you'd just traverse it all
05:02	Fender	well, that is ...
05:02	Fender	I think you don't know the mutable state when the lazy-seq is executed
05:03	Fender	IOW, you don't know when each lazy-seq is realized
05:05	Fender	so when it's realized it's calling the lexer but it might be that this is not in order
05:06	Fender	so if you have a lazy-seq and you first realize elements 0 and 1 and then deep dive into 0->0 then there could be a problem
05:07	Fender	in get-in syntax this would mean (get-in x [0]) (get-in x [1]) (get-in x [0 0]) would not be the intended order of traversal in a depth-first traversal because [1] should come after [0 0]
05:08	cfleming	I'm pretty sure in this case that the element should always be traversed in order
05:10	cfleming	Oh, I see the problem
05:10	cfleming	I'm not correctly checking for the case where the lexer has no more entries
05:11	cfleming	It's nothing to do with laziness or anything, just a common or garden bug :)
05:11	Fender	haha
05:12	Fender	let me guess, the when-let always returns something because of the vector decomposition?
05:12	Fender	(line 9?)
05:13	luma	no, when-let checks the value of the expression (token lexer), and if that is truthy, destructures that into [type text]
05:13	cfleming	No, in that case when-let... right
05:14	cfleming	I'm not quite sure how it's happening, but map-entry is somehow getting called when the lexer has no more elements, which it shouldn't. It doesn't check for that case, because it shouldn't have to - it should always get a closing }
05:16	Fender	I stand corrected
05:18	Fender	ok, well how about: map-entry is calling itself and collection-element as well
05:18	Fender	that's probably what you mean
05:20	Fender	anyone here knows how to reference a simple clj file with just definitions from cljs?
05:21	Fender	the clj file just contains def'ed code and no dependencies
05:21	Fender	and all of it without side effects
05:32	kungi	Programming: Solving problems yourself you created yourself ... :-\|
05:45	cfleming	Fender: So this is a little embarrassing: (= ClojureTokenTypes/LEFT_CURLY)
05:45	cfleming	(always true)
05:46	Fender	haha ok^^
05:46	cfleming	Ironically I'm actually doing this as part of prep for my conj talk, where I will be talking about how to fix just this sort of error :)
05:47	cfleming	s/fix/get warned about/
05:50	Fender	like in the old days when the compiler writing guys would have been happy to have a compiler that they could use
07:28	Glenjamin	does anyone know a good way to find out what has started an agent? My uberjar compilation is hanging while the agent pool closes
08:37	jeaye	Is there something like update-in which just accesses nested elements based on a "path" of indices?
08:37	filben	get-in?
08:37	jeaye	muahaha
08:37	jeaye	Makes sense; thanks.
08:37	filben	np
08:39	puredanger	Glenjamin: you can build a hacked version of Clojure that dumps stack at the point where an action is dispatched
08:40	Glenjamin	:'(
08:40	Glenjamin	i suppose maybe i could alter-var-root something if i get it in early
08:43	noncom	Glenjamin: also you could avoid building and just redefine things inside the core
08:43	noncom	although, i heard, it may be impossible with clojure 1.8+
08:52	puredanger	The th no you can't do in 1.8 is with-redefs of something in core and have other things in core see it
08:56	puredanger	But it's worth a try - the main things that dispatch are future and send
08:57	gfredericks	Glenjamin: user.clj is a good trick for alter-var-rooting things early
09:08	visof	hi guys
09:12	visof	assume i have list of methods like this (foo bar xxx yyy) and want to apply on something as (yyy (xxx (bar (foo something)))) but method's list has undetermined number of rules, what is the best way to do this (apply comp list-methods something) ?
09:12	visof	this is the right way to do this?
09:13	oddcully	what do you mean by "number of rules"?
09:14	visof	number of methods
09:15	visof	(foo bar xxx yyy) contain 4 methods, maybe 3 or whatever n methods in the list
09:15	oddcully	well apply comp does not look bad?
09:15	oddcully	,((apply comp [inc inc dec]) 5)
09:15	clojurebot	6
09:16	visof	oddcully: ok
09:19	visof	oddcully: but dec is applied first right?
09:19	gfredericks	yep
09:19	visof	(inc (inc (dec 5)))
09:20	visof	ah okay
09:20	visof	so i need to reverse before apply if i want to apply from the beginning of the list
09:22	oddcully	,(reduce #(%2 %1) 5 [inc inc dec])
09:22	clojurebot	6
09:50	phaseNi	,(-> 5 inc inc dec)
09:50	clojurebot	6
09:50	phaseNi	:P
09:56	justin_smith	,(-> 5 / / /)
09:56	clojurebot	1/5
09:56	justin_smith	,(-> 5 / / / /)
09:56	clojurebot	5N
09:56	oddcully	,(defmacro apply-rules [init fns] `(-> ~init ~@fns))
09:56	clojurebot	#'sandbox/apply-rules
09:56	oddcully	,(apply-rules 5 [inc str seq])
09:56	clojurebot	(\6)
09:58	timvisher	is anyone aware of a `safe-min` implementation somewhere in the standard libraries. something like `(defn safe-nil [&args] (->> args (remove nil?) seq (apply min))`?
09:59	justin_smith	no, but I'd do it as (reduce (fn [i n] (if (and n (< n i)) n i)) coll)
09:59	timvisher	justin_smith: 👍
10:00	justin_smith	timvisher: that symbol doesn't work in my irc client :(
10:01	justin_smith	haha, just found it in the log, same to you buddy :)
10:01	justin_smith	( http://clojure-log.n01se.net/ for those curious)
10:02	timvisher	justin_smith: ah. y u no emoji? :)
10:02	gfredericks	justin_smith: doesn't work for me in my client or my browser
10:02	timvisher	i don't have ascii art for thumbsup
10:02	justin_smith	timvisher: tty client running on a virtual ocean droplet - I guess it might be misconfigured?
10:02	justin_smith	gfredericks: it's a thumbs up
10:03	timvisher	justin_smith: mmm. i'm running in a tty session in erc in emacs and it displays for me. but i have fonts set up that can handle it. ¯\_(ツ)_/¯
10:03	timvisher	i wonder what that looks like? :)
10:04	gfredericks	that one looks fine
10:04	justin_smith	timvisher: yeah, it's somewhere between the terminal I am running natively, the tty settings on my vhost, and the settings on my irc client - I'm getting "unknown unicode" directly as a symbol - I assume the client does that?
10:05	justin_smith	timvisher: with broken unicode I expect to at least get some gibberish I can paste into another window and figure out what it really was
10:05	timvisher	justin_smith: i'd guess so. i think the character codes are still present so i'd expect that as well
10:06	justin_smith	I might just switch from this irc client to emacs running just so it can run erc
10:06	justin_smith	hah
10:06	justin_smith	at least I could trust it to handle weird characters
10:06	justin_smith	(even if the font is wrong, it will at least tell you the name of the character)
10:06	timvisher	justin_smith: i have a dedicated emacs instance running with just erc that i mosh to to irc :)
10:07	justin_smith	I might be joining that club
10:07	timvisher	i think i picked that up from technomancy
10:07	justin_smith	is mosh that much better than ssh + screen?
10:08	timvisher	justin_smith: mosh + (screen\|tmux) is _so_ much better than ssh + (screen\|tmux)
10:09	gfredericks	I've stopped using tmux and just use an emacs server now
10:10	justin_smith	that makes sense - emacsclient in a tty is cool
10:10	justin_smith	and who am I kidding - I don't need to do anything on this host I can't do inside an emacs window
10:11	gfredericks	yeah who are you kidding
10:11	gfredericks	it even works better than tmux for having multiple computers logged in
10:11	gfredericks	with tmux I always had to detach everything else so that I wouldn't get sizing constraints
10:12	justin_smith	with screen I learned to love "C-a F"
10:12	justin_smith	(force size to size of current screen)
10:12	gfredericks	I can't even remember anything about screen
10:12	justin_smith	ha
10:12	gfredericks	but I've learned I can use screen inside an emacs term buffer :)
10:13	tdammers	screen inside screen is where it gets weird
10:13	justin_smith	gfredericks: to me, tmux is that program I need to know how to use because I have projects where people think running lein run inside a tmux session is an OK way to run a server
10:13	justin_smith	tdammers: C-aC-a - easy!
10:13	gfredericks	justin_smith: I must be reverse of you; my team does a lot of prod stuff w/ screen
10:14	tdammers	justin_smith: simple vs. easy, huh
10:14	justin_smith	gfredericks: ugh, really everybody, use uberjars and nohup, or better yet, stop using printlns for logs and use a file appender
10:14	timvisher	justin_smith, gfredericks: i've been unable to get anything like the kind of isolation i'm used to with multiple emacs instances inside many tmux sessions in a single emacs server instance.
10:14	Schrostfutz	I'm doing a course on clojure and they introduce head recursion on the example of element count or frequencies, where they pass the count/frequencies to each recursive call. Is there a advantage of doing that instead of tailrecursion which should work there, too?
10:14	timvisher	everything that tries to solve that problem is an ugly hack compared to just running multiple instances.
10:16	tdammers	Schrostfutz: the problem with head recursion is that it leaks stack space; tail recursion can be TCO'd and thus run in constant stack space
10:16	timvisher	but my usage patterns are pathological in many ways, i'm sure :P
10:16	tdammers	Schrostfutz: I have no idea why one would not use tail recursion when that is possible, other than maybe pedagogical reasons
10:16	justin_smith	Schrostfutz: the question of tail recursion or not is much less important when the recursive call generates the next item in a lazy-seq (because the continuation gets turned into a thunk and no longer claims immediate stack), but otherwise I'd think tail recursion is always better
10:17	Schrostfutz	tdammers, justin_smith: okay, thank you.
10:17	Schrostfutz	tdammers: Even if it is pedagocial I think it is bad to use examples where it is the wrong approach
10:18	justin_smith	tdammers: I don't think you can build a lazy seq via tail recursion, but you can via non-tail recursion
10:18	tdammers	Schrostfutz: I'm thinking it might help illustrate the difference
10:18	Glenjamin	justin_smith: 12factor principles says log to stdout and let the process manager handle files/rotation etc :)
10:18	tdammers	justin_smith: well, as you said, when you're building a lazy seq, you don't need to TCO
10:18	tdammers	justin_smith: that's how Haskell gets away with not doing TCO at all (or always doing TCO, depending how you look at it)
10:18	justin_smith	Glenjamin: OK, but screen/tmux are not process managers :P
10:19	Glenjamin	heh, don't disagree there
10:19	Schrostfutz	tdammers: But then you should make sure that you mention tail recursion would be the better option
10:19	tdammers	Schrostfutz: agree
10:20	justin_smith	Schrostfutz: here's the thing - sometimes laziness is better, and laziness can't really be tail recursive
10:20	justin_smith	I don't think...
10:20	tdammers	in a way, it's not recursive at all
10:21	tdammers	as in, the recursive call is deferred
10:21	tdammers	transparent continuation-passing or something like that
10:21	Schrostfutz	justin_smith: yes, but we have not been introduced to anything lazy yet.
10:22	justin_smith	fair enough, sounds like bad choice of example then, unless they are leading to a brilliant gotcha
10:22	justin_smith	like "see how this blows the stack, now lets look at ways of preventing that"
10:22	justin_smith	(the whole teaching philosophy of "show why you need it, before showing the solution")
10:25	tdammers	someone at work just pasted an article about the problem/solution ordering thing
10:25	justin_smith	tdammers: that's what I was thinking of
10:25	justin_smith	the whole thing with video games, keys, doors
10:25	tdammers	yeah, that's the one
10:25	tdammers	headaches and aspirin
10:25	tdammers	monads and monad tutorials :D
10:26	justin_smith	tdammers: of course I see exceptions to this in the real world "show your child the consequences of running into traffic, then teach them to look both ways"
10:26	justin_smith	but in the digital world, we are lucky :)
10:26	tdammers	"have your child run into the traffic, then you won't need to bother with the teaching anymore" :x
10:26	justin_smith	lol
10:27	tdammers	also explains why security is such an orphan child in the digital world
10:27	tdammers	it's impossible to create the headache in a safe way there
10:28	justin_smith	That's true - by the time it hits, you are screwed. And you are strongly disincentivised to talk about the experience (admitting you had the problem makes you look bad in the market).
10:31	adamretter	I have inherited some Java code which is using Clojure as a library. I have a com.github.krukow.clj_lang.IPersistentVector and I somehow need to sort this by a key function (in Java). Can anyone give me any pointers to how to do this?
10:32	justin_smith	adamretter: if it behaves similarly to a clojure.lang.PersistentVector you can use the methods in java.util.collections to get it into an array or ArrayList and then use it natively
10:34	justin_smith	adamretter: sorry, I think I was wrong about collections there - but I know there is a way to get an arbitrary clojure sequential into an array or arralist
10:35	adamretter	justin_smith: having never written a line or clojure or worked with these collections before… I might need a bit more handholding ;-)
10:36	justin_smith	adamretter: sure - check the other interfaces it implements for one (IPersistentVector is not a type, it's an interface, right?)
10:36	justin_smith	adamretter: experimenting in my clojure to get you something concrete right now
10:37	justin_smith	adamretter: if you are comfortable with a bit of clojure (into-array v) should give you a java array of Object containing the elements of the vector
10:37	justin_smith	,(into-array Object [1 2 3])
10:37	clojurebot	#object["[Ljava.lang.Object;" 0x651f98f8 "[Ljava.lang.Object;@651f98f8"]
10:38	adamretter	justin_smith: yes it's an interface, but all the interfaces it implements are from Clojure, so I can't see how to tie it back to a Java array or whatever
10:38	adamretter	justin_smith: erm, sorry I don't know how to write `(into-array v)` in the equivalent java
10:38	justin_smith	adamretter: you can get into-array via clojure.lang.Var, and call it with the args of Object.class and v
10:40	justin_smith	clojure.lang.IFn into_array = clojure.lang.RT.var("into-array"); into_array.invoke(Object.class, v);
10:40	justin_smith	soemthing like this
10:40	justin_smith	it's easier in clojure code :)
10:40	adamretter	hmm RT.var doesn't seem to be a valid method
10:41	justin_smith	adamretter: https://clojurefun.wordpress.com/2012/12/24/invoking-clojure-code-from-java/ I missed an arg
10:41	justin_smith	the args are "clojure.core" "into-array"
10:41	justin_smith	but really that article above is better than my memory right now, heh
10:43	adamretter	justin_smith: hmm but com.github.krukow.clj_lang.RT doesn't seem to have a `var` method?
10:43	justin_smith	adamretter: no! clojure.lang.RT
10:43	justin_smith	you use clojure.lang.RT.var to look up vars
10:43	justin_smith	or do they have some weird version of clojure they are using?
10:43	adamretter	justin_smith: ah so I think the issue os that the project is using this (I just googled it) https://github.com/krukow/clj-ds
10:44	justin_smith	adamretter: OK, I thought you were using clojure
10:44	justin_smith	adamretter: in that case, yeah I'd see what interfaces that object implements, and one of them should give you a toArray or iterator
10:44	adamretter	justin_smith: yeah so did I
10:47	justin_smith	adamretter: looks like that persistentvector has an iterator method, and it should implement count too, you could easily build up an array from its contents given those
10:47	adamretter	justin_smith: okay cool, I will try that, thanks :-)
11:06	justin_smith	TIL instead of "who am i" you can run "who killed jfk" and get the same output
11:15	TimMc	"If ARG1 ARG2 given, -m presumed: `am i' or `mom likes' are usual."
11:15	TimMc	TIL
11:16	justin_smith	TimMc: sadly "who is your daddy" is rejected - too many args
11:25	justin_smith	adamretter: also, looking at krukow.clj_lang.RT - it has a toArray method that should work if you pass the vector in
12:51	Glenjamin	anyone know a similar shorthand to (-> (doto prn)) which works with ->> ?
12:54	muhuk	what are you doing to prn? that's cruel
12:55	Schrostfutz	Is there a way to have a helper function that's only available from within a function?
12:55	justin_smith	Schrostfutz: yes, via fn or letfn
12:55	justin_smith	Schrostfutz: though we don't do as much information hiding, immutability reduces its utility
12:55	Schrostfutz	justin_smith: can the function also be recursive?
12:55	justin_smith	yes
12:56	justin_smith	(fn foo [] (if hmm? (foo)))
12:56	justin_smith	or just via recur also
13:04	Schrostfutz	justin_smith: ah, thanks.
13:08	Schrostfutz	justin_smith: Am I doing something wrong or will recur not work when using the #() notation?
13:08	justin_smith	,(#(if (< % 0) % (recur (- % 10))) 42)
13:09	clojurebot	-8
13:09	justin_smith	that would be much more readable using fn, but recur works there
13:29	{blake}	Does asyc.core use "port" and "channel" interchangeably?
13:40	amalloy	a channel probably has two ports, if i had to guess. the read and write ports
13:45	{blake}	Hmmm. We pass the channel to both puts and gets, ref'ed as "port", but for close! (and I think close! alone) it's ref'ed as "chan".
14:49	baz_	hi, have a logging related question
14:50	baz_	I'm using the tomcat-embed-jasper dependency
14:50	baz_	when I run my program (lein run)
14:50	baz_	I get jasper related logging
14:51	baz_	something like
14:51	baz_	INFO: At least one JAR was scanned for TLDs yet contained no TLDs
14:51	baz_	I would like to disable this output
14:51	baz_	currently looking at clj-logging-config
14:52	baz_	but something like (set-logger-level! "org.apache.jasper.servlet.TldScanner" :off) doesn't work
14:53	baz_	any hints on how to approach this?
15:18	justin_smith	baz_: it might be easier to make a plist file
15:24	baz_	justin_smith: not familiar with a plist file, where can I find more information?
15:25	justin_smith	baz_: http://tutorials.jenkov.com/java-logging/configuration.html
15:26	justin_smith	maybe that's actually a "properties" file now that I reconsider
15:32	baz_	mmm, I would prefer a programmatic way with clj-logging-config
15:47	ambrosebs	Bronsa: can you release a tools.analyzer version with this commit? https://github.com/clojure/tools.analyzer/commit/ef985c4a193470b13edb8822e9b74a1dc1368626
15:48	Schrostfutz	Can I have nested anonymous functions? If so, how do I get the arguments?
15:48	{blake}	Schrostfutz: You can't nest the #() notation but you can nest (fn[x y]...) till the cows come home.
15:49	{blake}	,((fn[a b] ((fn [x y] (+ x y)) a b)) 2 3)
15:50	clojurebot	5
15:50	{blake}	Schrostfutz: Terrible example, but you get the idea?
15:51	Bronsa	ambrosebs: sure
15:52	ambrosebs	Bronsa: thanks, just requires a few changes and I'd rather fix them now.
15:55	{blake}	Given an vector of symbols, is there an elegant way to sort them in an arbitrary way? So, the vector might use :a :b :c :d, but I need them in :d :a :c :b?
16:00	Schrostfutz	{blake}: yes I do.
16:01	ambrosebs	Bronsa: will that commit break core.async?
16:02	Bronsa	unlikely
16:02	{blake}	,(sort-by {:a 2 :b 4 :c 3 :d 1} [:a :b :c :d])
16:02	clojurebot	(:d :a :c :b)
16:03	{blake}	Neat.
16:05	luma	,(defn ->order [s] (zipmap s (range)))
16:05	clojurebot	#'sandbox/->order
16:05	luma	,(sort-by (->order [:d :b :a :c]) [:a :b :c :d])
16:05	clojurebot	(:d :b :a :c)
16:08	{blake}	luma: Nice!
16:15	Schrostfutz	What is wrong with something like this: #(func param %)? The compiler does not expect % it seems...
16:18	hiredman	the compiler actaully has nothing to do with %
16:19	hiredman	by the time the reader is done with #(func param %) % is gone
16:19	hiredman	,'#(func param %)
16:19	clojurebot	(fn* [p1__25#] (func param p1__25#))
16:20	hiredman	the error is almost certainly in the surrounding context, and it is hard to say what it is because you have edditorialized it and halfway incorrectly diagnosed it
16:20	hiredman	likely you are using -> or ->> without understanding that they are purely syntactic transforms
16:21	hiredman	or you are trying to nest #() forms, which isn't allowed, or func just doesn't take the arguments you thing it does
16:21	hiredman	to narrow that down you need to paste bin the actual error you get
17:52	gfredericks	does cljs have a mechanism for programmatically generating docstrings, via alter-meta! or equivalent?
18:05	neoncontrails	Has anyone worked through the canonical Functional Data Structures textbook?
18:06	neoncontrails	Sorry... Purely Functional Data Structures (Okasaki)
18:06	amalloy	~anyone
18:06	clojurebot	Just a heads up, you're more likely to get some help if you ask the question you really want the answer to, instead of "does anyone ..."
18:06	neoncontrails	Heh. Touche, clojurebot
18:07	dnolen	gfredericks: at runtime? no since docstrings aren't a thing at runtime
18:07	clojurebot	Excuse me?
18:07	neoncontrails	I'm wondering the applicability of Okasaki to Clojure specifically, as all the textbook exercises are ML with a dash of Haskell
18:07	gfredericks	dnolen: the use case is reducing duplication in docstrings; I'm guessing I'll just have to put up with it?
18:08	amalloy	clojure still has functions. you can do the exercises in clojure, and mostly just skip the types. you do have to at least recognize ML type signatures to know what you're supposed to implement
18:13	neoncontrails	amalloy: would the data structures translate well into a React environment.? I'd like to have a better understanding how to exploit the monolithic "app-state" paradigm
18:15	amalloy	beats me. i'd guess not, but i'm no expert
18:25	didibus	I've been wondering inside a let expression, it seems I cannot do _ (println "hey") more then once. Anyway around it?
18:27	didibus	Hum, nevermind, it seems it works
18:27	didibus	I must have something else that's the issue
18:29	TEttinger	,(let [_ (print "hey, ") _ (print "party ") _ (print "people!") _ 5] _)
18:29	clojurebot	hey, party people!5
18:32	didibus	I just found my problem, I was trying to bind a name that I have a function defined for, so it ws complaining about how it can't cast the bind into an IFn
18:32	McDougal	Hi, is anyone here using luminus?
18:32	didibus	And that was causing the let to fail past that point
19:19	didibus	Do (deftest) run in the order they are declared? And do they run one after the other or in parralel?
19:21	vilmibm	didibus, run in the order you declared, sequentially
19:21	didibus	ok, thanks
19:40	dnolen	gfredericks: need some more context on what you are trying to do?
19:41	dnolen	you want to automatically generate docstrings for some fns w/o having to write a macro or something?
19:46	gfredericks	dnolen: I don't care what I have to write, I just have 5 functions whose docstrings are 95% identical
19:46	gfredericks	I'll show you how I'm doing it in clj-jvm
19:47	dnolen	gfredericks: you can this with a macro then
19:47	gfredericks	https://github.com/clojure/test.check/blob/6a2f74d4088c11bb16b26899c63fe6887ac17c25/src/main/clojure/clojure/test/check/generators.clj#L598
19:47	dnolen	just add :doc meta
19:47	gfredericks	oh right
19:47	dnolen	s/can/can do
19:47	gfredericks	I'm so used to punching vars that I don't think of macros for that :)
19:47	gfredericks	cool, thanks
19:48	amalloy	gfredericks is just embarrassed to admit he doesn't know how to use macros
19:48	gfredericks	it's a bit less composable, but it works in this case
19:49	numberten	is there a core function for this functionality: (fn [pred f x] (if (pred x) (f x) x))
19:49	numberten	it seems like that would be common, but I can't think of anything off the top of my head
19:50	dnolen	gfredericks: yeah alter-meta! unfortunately in ClojureScript works on runtime ref types
19:51	dnolen	so that excludes using it for banging on compiler information like var metadata
19:51	gfredericks	right
19:52	amalloy	well alter-meta! does the same thing in clj-jvm, right? it's just that vars are also runtime ref types
19:53	gfredericks	yeah
20:09	gfredericks	oh actually
20:09	gfredericks	in clojure you can also use expressions for the docstring
20:09	gfredericks	in either metadata position
20:09	gfredericks	I wonder if that works in cljs too
20:11	celwell	Hello, I recently added some java code to my lein project (using :java-source-paths in project.clj). It works well when I 'lein ring server', but when I deploy to my AWS instance I'm getting: java.lang.UnsupportedClassVersionError: ...... : Unsupported major.minor version 52.0
20:12	hiredman	because the java on your aws instance is older than the java on you local machine where you are compiling your java class files
20:13	amalloy	you can fix it by adding a thing in your project.clj saying what version of java to target when compiling
20:13	celwell	How can I target lower version? I tried :javac-options ["-target" "1.6"] but it didn't help.
20:13	celwell	maybe I need to try some even older version
20:14	hiredman	if I recall it is actually kind of a pain to do that, have you considered upgrading your aws instance to a newer version of java?
20:14	celwell	I will look into that, I'm actually on AWS Elastic Beanstalk, using Tomcat 7 server, I'm not sure how easy it is to choose java version.
20:15	hiredman	52.0 is java 8 (jdk 1.8), and I think java 7 is already EOL
20:15	gfredericks	nope :(
20:16	amalloy	that -target stuff works fine
20:18	hiredman	apparently you can run in to issues if you don't also set the bootclasspath to point to the rt.jar for the correct java version, but I don't think I have every run in to that
20:19	hiredman	https://docs.oracle.com/javase/8/docs/technotes/tools/windows/javac.html#BHCIJIEG
20:22	amalloy	yeah, in theory that is a problem but in practice it has never mattered to me either
20:50	dnolen	people should try ClojureScript master if they can - we're going to ship a new release on Friday - many fixes
20:54	gfredericks	is there a portable way for checking if a transient set contains an element?
20:55	dnolen	@gfredericks hrm don't think so
20:55	gfredericks	welp that's what cljc is for I guess :)
20:55	dnolen	https://github.com/clojure/clojurescript/releases/tag/r1.7.166
20:56	dnolen	actually just try the prelease should hit Maven shortly
20:57	McDougal	How is the web story for clojure nowadays ref basic stuff like emailing html templates, image resize, etc? And how does performance compare with a Go web app?
21:10	owlbird	what's the best way to do if-return earlier in clojure?
21:13	McDougal	Is there an elseif in Clojure?
21:13	justin_smith	McDougal: cond
21:14	McDougal	justin_smith: Aha, gotcha. Thanks. Btw, would you use jetty or immutant or http-kit for a persistence heavy CRUD app?
21:14	gfredericks	I'm finally adding generators to test.check for collections of distinct elements (of particular sizes, optionall)
21:14	gfredericks	it's harder than it sounds
21:15	justin_smith	McDougal: I'd use ring, use the jetty adaptor during dev because that's just easy, and then leave the production decisions based on how you want to deploy
21:16	McDougal	justin_smith: Thanks. Being new to lisp, how long do you think it may take for the simplicity of lisp to kick in. I can get an app working, but at the mo, it sure does feel v diff. As its so new, more thinking everything through vs simplicity. I'm hoping to have that aha moment ref lisp vs reg OO
21:18	justin_smith	McDougal: well, of course complexity is different from unfamiliarity. There are a lot of little revelations to find. One of them is realizing that you rarely need to hunt through code for a needle in a haystack to see why somthing ended up the state it is in - immutable values mean you just look at the immediate context and call stack
21:20	McDougal	justin-smith: I'm about a week in and stuff gets hard wired quicker on a real project. So I'll just keep at it till its fluent
21:22	McDougal	Is clojure-toolbox the best place to look for libs?
21:24	owlbird	It's fantastic to write web app by using clojure (compojure) :-)
21:26	sotojuan	:-)
21:26	justin_smith	McDougal: I start with google to find leads, then crossclj.info to see who uses the lib and how, then github to do a sanity check on the repo / code / developer activity
21:27	justin_smith	McDougal: also, sometimes the best option is to just use interop with a java lib - it's not hard, and there's java libs out there for pretty much everything it would be reasonable to do with clojure
21:28	justin_smith	McDougal: I know that as a newcomer the exciting part is fp, but clojure makes a good lightweight glue for using a few java libs too
21:29	justin_smith	(lightweight in developer time / energy, not lightweight in machine resources)
21:30	McDougal	justin_smith: Thank you, am checking crossclj.info. When you say who the lib is used by, you mean companies or inidividual devs. I agree, it would be good to get a handle on java interop for max flexibility.
21:30	justin_smith	McDougal: I mean look at how widely used it is, as well as what code that uses that lib looks like
21:32	McDougal	justin_smith: Thanks, that's a more holistic approach to gauge lib quality. What have you settled on for rendering views? I'm looking at Hiccup and Selmer.
21:33	justin_smith	McDougal: I'm a contributer to the caribou project (not super active right now, we used to have a company funding us but no longer...) - we have our own markup lib called antlers that I use, but it's similar to selmber. I like hiccup for ad-hoc stuff, especially making templates out of existing html and then doing data transformations. Also I use reagent, which uses hiccup syntax. So yeah, hiccup is great too.
21:34	justin_smith	but for something a designer or frontend-only dev might touch? antlers or selmer is better for that
21:35	McDougal	justin_smith: I looked at caribou about a year ago, it has a v nice admin and looked really slick for doing crud type apps. So clojure community still not leaning towards frameworks for productivity?
21:36	justin_smith	no, for the most part not. Though liberator is a great "framework" for doing REST right.
21:38	McDougal	Prob because its so easy to stitch things together with just the needed libs. Thank you for the tips, I'm having a lot of fun with clojure, its stretching my mind in a v diff way
21:39	justin_smith	McDougal: for some things though, like security, a framework would be so much better
21:39	justin_smith	because security is a weakest link kind of thing, and that's where loose ad-hoc collections tend to fail
21:40	McDougal	justin_smith: I saw the talk on that. Have you found a good approach, mix of libs to plug that hole?
21:41	justin_smith	kind of - I mean, bcrypt, make sure you have nginx with ssl as a reverse proxy (because jvm ssl is a pain in the ass, not worth it)
21:42	justin_smith	the ring middlewares for importing params, clojure.java.jdbc for prepared statements instead of string concatenation for sql
21:42	McDougal	Yeah I always use that, got into bcrypt habit from rails exp. Haven't done the ssl on nginx as reverse proxy tho.
21:43	McDougal	So with string concatenation sql injection is still wide open?
21:43	justin_smith	McDougal: I mean, if you string concatenate and get stuff from a user, how can any environment prevent vulns there?
21:44	McDougal	Gotcha, that makes sense. Ref ssl reverse proxy, does that mean running the entire app in ssl or just persistence?
21:45	justin_smith	it means all access through ssl via the reverse proxy, yeah
21:45	justin_smith	and letting nginx do all the work
21:46	McDougal	That's a good default. What are you using for persistence, java.jdbc or some other lib?
21:48	McDougal	Am leaning towards yesql
21:49	sobel	i just write functions that isolate the queries/jdbc access
21:50	justin_smith	right now? a mixture of caribou's persistence layer (a map oriented thing built on top of jdbc) for the data that really matters and monger (mongodb) for stuff that needs to be fast cheap and easy and we could totally live if it all crashed and burned and we had to recreate the dataset
21:52	owlbird	I've tried compojure/jdbc a few days, and figure out that the best structure of a web app only has 3 files, project.clj, db.clj, handler.clj, and write all business logic and jdbc/query in the handler.clj.....
21:53	justin_smith	owlbird: that works until you have thousands of lines of handler, heh
21:53	McDougal	Gotcha. I'll have to try monger, first foray into nosql. Mostly postgres so far. I'll check into java interop in clojure for the brave, he does pretty good coverage on it
21:53	justin_smith	mongo has some bit gotchas so far in my experience - unless we just use it all wrong :P
21:54	justin_smith	eg. updates leaving a thread open trying to read a socket, and the thread and socket never being released until the app crashes because it runs out of one or the other...
21:54	McDougal	justin_smith: Have you seen Rethinkdb, its an interesting nosql project
21:54	justin_smith	yeah, I've seen it
21:54	justin_smith	almost tried it once
21:54	McDougal	How about Cassandra or any graph dbs?
21:54	justin_smith	McDougal: from a clojure point of view. datomic is pretty interesting
21:55	McDougal	justin_smith: What's the pricing model on Datomic?
21:55	justin_smith	McDougal: we are doing a lot of heavy duty graph stuff, but found that our graphs were too dense for the graph dbs to really pay off -- once a graph is dense enough regular tables make sense again
21:55	McDougal	Datomic is immutable db right?
21:56	McDougal	Which graph dbs did you try out?
21:56	justin_smith	I think that's a good way to put it - yeah - of course you can do inserts / drops / updates, but it's all done with snapshots of time
21:56	McDougal	Is the benefit in Datomic performance or an audit trail?
21:57	justin_smith	McDougal: the stuff about graph dbs is second hand actually, my team / tech lead tried them before I got hired, and I don't remember all the names, but I know they tried a few
21:57	justin_smith	McDougal: correctness
21:57	justin_smith	and avoidance of some common concurrency related mistakes that happen even with a proper transactional db
21:58	McDougal	I'll check it out, at v least as its Rich Hickey. The graphdb I was checking out is orientdb for a recommendation engine
22:00	mysamdog	Hey, does anyone here use dommy?
22:00	mysamdog	I can't seem to get scroll events to work, but click events work just fine
22:01	McDougal	V interesting, a free tier on Datomic, I'm def going to try that, would be a good learning experience
22:03	mysamdog	(dommy/listen! (dommy/sel1 :body) :click check-scroll) works, but (dommy/listen! (dommy/sel1 :body) :scroll check-scroll) doesn't
22:03	McDougal	justin_smith: Is Datomic considered a relational or nosql db?
22:09	mysamdog	Nvm, I figured it out
22:09	mysamdog	I replaced (dommy/sel1 :body) with js/window
22:12	McDougal	justin_smith: Thanks for all your tips, much appreciated. Going through the Datomic docs.
22:59	matthavener	#
22:59	matthavener	whoops
23:23	wegry	Hey all, I'm wondering if anyone has used cljs-ajax here?