#clojure – 2016-02-11

2016-02-11

00:18	tolstoy	justin_smith: Remember that "node.js sockets on windows" discussion a few days back? Turns out (™), I had to execute those sorts of things in the "main" process, not in the "render" process. Why it worked great on OSX and Win7, I've no idea.
01:30	renl	Hi may i ask for gen-class, can the class be compiled into .java instead of bytecodes so I can check what code did the gen-class create?
01:43	MasseR	renl: you can always decompile the class
01:43	renl	k thanks :)
01:44	renl	is :state in gen-class fields in a java class?
02:25	renl	anyone used Coinor Ipopt on clojure? or for that matter are there any nonlinear programming library for clojure out there?
02:38	Voxnihili1618	hey
04:07	python476	hi, I get stack overflow with a function of two signature http://pastie.org/10717536
04:07	python476	calling (f) overflow, calling (f <default>) runs fine
04:08	python476	is it misguided to define a fun (defn f ([] (f <default>)) ([a] <real-logic>)) ?
04:09	opqdonut	no that's normal
04:10	opqdonut	the problem is you're calling "(rl [i 32])"
04:10	opqdonut	but you meant "(rl i 32)"
04:10	opqdonut	do you get the differences?
04:11	python476	wtf do I
04:11	python476	I did
04:12	python476	opqdonut: I often do this typo .. I need to rest
04:14	python476	thanks a lot donut
04:37	CStorm	Building a very small api in clojure. I grab some data from an API and saves/replace it to a db ever x hour. Then an app can get that data from my API. I am new to clojure, so which database should i use for this simple project?
04:42	schmir	CStorm: sqlite or H2 may be suitable.
04:42	schmir	or just keep it in memory
04:43	hiredman	the sqlite options for the jvm are not very good, h2 is very odd about multithreading, use derby
04:43	CStorm	maybe i should start doing it en memory and then just move it to a db after
04:45	CStorm	and what about deployment, which should i go for? heroku, digitalocean? were do most deploy their clojure?
04:45	schmir	I didn't run into any problems with sqlite.
04:45	CStorm	if i dont wanna roll my own.
04:45	CStorm	wrote all three possiblities down, schmir and hiredman.
04:52	qsys	CStorm: I usually use H2 for that kind of apps
04:52	CStorm	thanks.
04:52	qsys	I used to think to store it as plain datastructures (compressing with nippy)
04:53	qsys	but I don't see the point of not using a db
04:53	qsys	and I would use 'lightweight datomic' if available :p
04:53	qsys	datascript might be a kind of an option, but that's very browser-oriented
04:53	qsys	so I prefer H2 so far...
04:59	CStorm	thanks.
05:01	hiredman	http://www.h2database.com/html/features.html#multiple_connections explains that h2 synchronizes (serializes via locks) access to databases by default, and if you read further the setting to change that is considered experimental (and has been for I think years now)
05:04	CStorm	Where should i deploy it all if i just want to get something going quickly?
05:05	qsys	true, but never had any issues with it so far, with H2 for small applications. Since v >1.4, it uses MVCC, so no locking
05:05	hiredman	qsys: that is, as far as I know, not true
05:11	WickedShell	is there a way to change where lein is using for scratch space? it keeps filling up disk C (on windows atm sadly) which causes all sorts of problems. I have tons of scratch space on other drives, but C: optimistically has 500mb at the start of the day...
05:12	wmealing	WickedShell: good question, does it put it in temp ?
05:14	WickedShell	wmealing, no clue, I'm assuming, although I'm looking, this is the error I see: http://pastebin.com/cw2ZRSy1
05:14	WickedShell	and of course the fact that there are now 0 bytes free...
05:14	wmealing	ok, lets have a look
05:15	wmealing	i assume its https://github.com/technomancy/leiningen/blob/master/src/leiningen/javac.clj
05:15	wmealing	line 12 makes me think that
05:15	wmealing	its probably
05:15	wmealing	(let [options-file (File/createTempFile ".leiningen-cmdline" nil)]
05:15	wmealing	line 64
05:16	WickedShell	seems reasonable, although I'm working off a different disk
05:16	wmealing	ok
05:16	wmealing	yep
05:16	wmealing	it seems to call javas interpretation
05:16	wmealing	java.io.File
05:16	wmealing	i'm thinking, and i haven't confirmed yet
05:17	wmealing	is that java looks at the windows environment variables
05:17	wmealing	to find where to store tmp files
05:17	wmealing	so, stackoverflow suggests its %TEMP%
05:18	wmealing	start->run->%TEMP%
05:18	WickedShell	hmm yeah that's on C
05:18	wmealing	ok
05:18	wmealing	so, again windows isnt my thing.. i think you can set that
05:18	wmealing	http://answers.microsoft.com/en-us/windows/forum/windows_7-files/change-location-of-temp-files-folder-to-another/19f13330-dde1-404c-aa27-a76c0b450818?auth=1
05:18	wmealing	see the answer given there
05:19	wmealing	starting with "hi mike"
05:19	WickedShell	yeah I can change that, (ironically my temp is only 70 megs :P)
05:19	wmealing	righto !
05:19	wmealing	btw, might be time to clean up C
05:19	wmealing	if you're using a modern windows partition
05:19	wmealing	sorry, not partition
05:19	wmealing	version
05:19	WickedShell	64GB SSD was not enough....
05:19	wmealing	do you realise that symlinks work ?
05:19	WickedShell	the whole windows side by side store thing is awful :P
05:19	wmealing	ie, to make a directory on another disk appear on another drive
05:20	WickedShell	Yeah I have a fair amount of the My Documents etc pointed elsewhere, didn't realize it had proper symlinks
05:20	wmealing	yeah, me neither till not long ago
05:20	WickedShell	a couple of programs (pcb design tools etc) require ~2GB's a pop on C and wouldnt install anywhere else...
05:20	WickedShell	was really annoying
05:21	wmealing	what i did, was install it… then copy it to another disk
05:21	wmealing	then make the symlink
05:21	wmealing	to that new disk
05:21	wmealing	this doesn't work for system things though
05:21	wmealing	only for non core.. stuff
05:25	wmealing	WickedShell: do you need to reboot for that to work ?
05:26	WickedShell	no, usually need to reload any command prompts/enviroments there but otherwise no
05:26	wmealing	oh ok
05:28	WickedShell	thanks
05:28	wmealing	WickedShell: working ?
05:29	WickedShell	yeah
05:29	wmealing	WickedShell: awesome ! have bucketloads of fun
05:30	wmealing	thankyou for flying clojure airlines.
08:18	jweiss	what's the recommended way to factor out common code from a defn where the different arities share code? private function in the same ns?
08:22	opqdonut	jweiss: if you can't just delegate to the more specific arity, then yeah private function seems apropos
08:29	Kamuela	Private functions are achieved how?
08:30	opqdonut	(defn- foo ...)
08:30	opqdonut	which just does (defn ^:private foo ...)
08:30	luma	(defn ^:private foo ...) is the preferred way
08:31	opqdonut	is it?
08:31	opqdonut	why?
08:31	clojurebot	why is Why
08:32	ridcully	Why?
08:32	clojurebot	Why is the ram gone
08:32	ridcully	so true
11:10	sdegutis	Is there a name for this kind of transformation? [[:a] [:b :c] [:d]] => [[:a :b :d] [:a :c :d]]
11:11	luma	cartesian product
11:17	sdegutis	Thanks luma.
11:17	Kah0ona	quick question about testing with Midje. when i (use 'midje.repl), and then run some test, it seems my test environment variables (using environ.core) aren't picked up, instead it picks the 'dev' environment vars
11:18	Kah0ona	anyone any idea where I should specify it? I do `lein repl` -> `(use 'midje.repl)` -> `(autotest)`
11:23	Kah0ona	ah start the repl with-profile +test...
11:23	Kah0ona	duh. :)
11:48	benjyz1	hello. I have a question about protocols and methods
11:48	benjyz1	I have what in Java would be an Interface. I have several of them, and a wrapper around it, i.e. a facade pattern
11:49	benjyz1	what would this be in Clojure? I would define the interface as a protocol?
11:50	benjyz1	it is not a protocol, but it doesn't apply to different types.. perhaps someone has an idea
11:55	justin_smith	benjyz1: in clojure protocols are needed in order to have methods, even if only one type implements it (unless you use gen-class or an existing interface)
11:59	justin_smith	benjyz1: what you want is precisely a protocol - that is how we do facades in clojure
12:01	benjyz1	any different between records and types? I guess in OO everything being a class mixes many different things together
12:02	benjyz1	*difference
12:02	justin_smith	benjyz1: defrecord and deftypes both create classes
12:02	justin_smith	benjyz1: clojure doesn't hide the jvm class system, it just provides opinionated tools that simplify it
12:03	rhg135	A record is merely a class with some implementations
12:03	benjyz1	yes. so far I've taken the approach to avoid types and classes altogether. which works well on a small scale
12:03	justin_smith	benjyz1: there are no types
12:03	rhg135	Importantly, Associative
12:03	justin_smith	deftype and defrecord create classes.
12:03	justin_smith	defrecord automatically implements clojure's hash-map methods
12:04	justin_smith	(in the generated class)
12:04	benjyz1	ok, I see. I think generally class and object and type are now very precise concepts
12:04	benjyz1	*not
12:04	justin_smith	benjyz1: the jvm has classes and primitives
12:04	justin_smith	benjyz1: we do not implement anything in clojure that isn't a class
12:05	justin_smith	benjyz1: contrast to scala which enforces abstractions that don't exist in the bare vm, we don't attempt this
12:05	benjyz1	ah, that's where the mess in scala comes from ^^
12:06	justin_smith	haha
12:07	Glenjamin	wouldn't protocols fall into that category?
12:08	benjyz1	is it a bad idea to have deftypes with the same name as a namespace?
12:08	justin_smith	benjyz1: deftypes should use CamelCase like you would use for Classes
12:08	justin_smith	(as should defrecords)
12:23	rhg135	Not really, Glenjamin, the builtin nashorn engine does it too,
12:23	justin_smith	Glenjamin: do protocols enforce any restrictions their underlying Interface would not?
12:23	justin_smith	Glenjamin: we add functionality but not restrictions, is my impression
12:26	Glenjamin	i see, they're effectively liskov substitutable for interfaces
12:27	justin_smith	I think so
12:28	rhg135	Not exactly. If you pass one extended dynamically the method calls fail
12:33	justin_smith	rhg135: wait, since you can't dynamically extend Interfaces, doesn't this still fit liskov?
12:33	justin_smith	maybe I'm confused
12:34	rhg135	you may be right.
12:34	rhg135	I thought it meant b must work where a does.
12:35	justin_smith	my intent was that protocols can do all things interfaces do, while offering other features as well
12:36	rhg135	Yeah, they're nice.
12:36	justin_smith	under the umbrella of clojure adding functionality but not adding extra restrictions to what the vm offers (unlike eg. scala)
12:36	justin_smith	agreed!
12:37	justin_smith	or would a scala expert counter that the jvm level features will all work and the restrictions are only on scala specific extensions in the same way? I don't know scala well enough to address that, but I wonder.
12:38	rhg135	I think #scala exists
12:39	justin_smith	yes, I might just have to go ask that question
12:39	rhg135	Good luck!
12:51	justin_smith	#scala says "using scala from other langs is a pain in the ass, but can be possible if you are careful to implement all features as java interfaces in the scala code"
12:51	justin_smith	so there we go
12:51	justin_smith	no attempt at the liskov thing there
12:59	rhg135	I guess by pita they mean more than RT.resolve(...).invoke()
13:01	justin_smith	right, they mean it isn't even safe unless the scala is restricted to a java interface
13:01	rhg135	Oh dear. That's bad
13:01	rhg135	Really bad
13:02	justin_smith	there are certain constraints that the scala compiler understands that aren't even represented at the vm level
13:02	yuung	i'm writing a small blog application with clojure. coming from a rails background, i'm very used to the MVC pattern. i was wondering what your thoughts are regarding how I should implement models with clojure/how to handle db interactions?
13:02	justin_smith	so you can try it outside scala if you want but who knows what you get? haa
13:03	yuung	or if i should even stick with the MVC paradigm with a functional language
13:03	yuung	the only library i'm using is ring, and handlers sound a lot like controllers to me
13:04	rhg135	Isn't that like protocols? You get java features but if you use more it won't work
13:04	justin_smith	yuung: well, the typical preference in clojure is to use vanilla clojure data like hash-maps and lists and vectors, and even something as simple as clojure.java.jdbc will easily extend that to the db
13:04	yuung	justin_smith, yeah; i've got jdbc working. just wondering if there was an established pattern
13:05	yuung	justin_smith however i'm happy to use poco :)
13:05	sdegutis	I don't think that's what it's really called.
13:05	yuung	i guess plain old clojure objects is kind of a contradiction... let's say pocd
13:05	sdegutis	It's almost like transposing.
13:07	rhg135	pod
13:08	justin_smith	data :)
13:09	rhg135	But, acronyms are cool
13:09	yuung	ikr ;p
13:10	justin_smith	yuung: you can get pretty far with a record in db becoming a hash-map in clojure, and we have existing tools to put hash-maps into classes when we need to attach custom behaviors for OO (via defrecord).
13:10	yuung	justin_smith what should i google for the hash-map -> classes thing? also doesn't that kind of break the philosophy of fp?
13:11	rhg135	Isn't that a subset of ORM?
13:11	justin_smith	yuung: we use OO unashamedly
13:11	clojurebot	Pardon?
13:12	stoopkid	hi is clojure a total functional programming language?
13:12	justin_smith	stoopkid: no
13:12	rhg135	I don't think of records as OO
13:12	rhg135	More like optimization
13:13	justin_smith	yuung: when you do (defrecord Foo [field field2 ...] SomeInterface (someMethod [this ...] ...)) it creates a function map->Foo which turns a hashmap into a Foo
13:13	justin_smith	rhg135: they tie behaviors to data, that's OO
13:13	rhg135	You could always use anonymous classes
13:13	justin_smith	it's not the shitty part of OO
13:13	justin_smith	but still OO
13:13	rhg135	True
13:14	rhg135	They're hardly OO though
13:17	justin_smith	rhg135: I consider inheritance a parasite on programming that primarily latched onto OO
13:18	rhg135	Lol
13:19	rhg135	But lately I've found that I get many code-induced nightmares due to things other than inheritance
13:24	rhg135	When's that?
13:26	justin_smith	april 15-16 but I am going a day early for the datomic training
13:26	justin_smith	also they billed my opportunity grant donation as if it was a ticket which is slightly odd
13:27	rhg135	That's not too far off
13:27	rhg135	I'm so excited
13:28	justin_smith	well they asked me who the opportunity grant was for so I clicked "I don't know yet" so they said it was snoozed or something
13:30	rhg135	I wonder what the talks will be about
13:31	justin_smith	an ex-coworker of mine got the official approval for a talk about learning clojure as a junior programmer, so her talk is probably just going to be about how I'm a huge jerk.
13:32	rhg135	Lmao, I need to watch that one
13:39	sdegutis	Does this make sense? (= [[:a :b :d :e] [:a :c :d :e] [:a :b :d :f] [:a :c :d :f]] (f [[:a] [:b :c] [:d] [:e :f]]))
13:40	sdegutis	Or https://gist.github.com/sdegutis/6bcbafa56cebb07a9da3 for pretty-printed version.
13:40	sdegutis	I have no idea what this kind of transformation is called.
13:44	sdegutis	Oh yeah cartesian-product does look right actually.
13:46	rhg135	A deduplicated one
13:47	amalloy	sdegutis: in haskell that function is called sequence. in clojure we don't really have it built in, but it's not too ahrd to write with a (for ...) that calls itself recursively
13:47	binjured	asked my wife we could name our first child amalloy, she said no and also we don't want children remember. i tried man!
13:47	amalloy	haha
13:47	sdegutis	amalloy: apparently it's clojure.math.combinatorics/cartesian-product
13:48	amalloy	yes, that too
13:48	sdegutis	Except it results in the middle two collections being swapped.
13:48	sdegutis	amalloy: Hmm thanks for the idea of recursive (for)s. I would like to do it that way preferably.
13:48	sdegutis	However I don't know how to implement it. I never took any CS classes or went to university.
13:49	sdegutis	I went to junior college and all I learned there was Visual Basic .NET
13:49	binjured	that's basically lisp ducks
13:50	sdegutis	Hmm the implementation of clojure.math.combinatorics/cartesian-product uses (loop).
13:51	amalloy	,((fn cart [coll] (lazy-seq (if (empty? coll) '(()) (for [more (cart (rest coll)), x (first coll)] (cons x more))))) '((a b) (c) (d e) (f)))
13:51	clojurebot	((a c d f) (b c d f) (a c e f) (b c e f))
13:51	amalloy	recursive for is an important pattern to get the hang of. it's everywhere, if you start viewing more things as trees
13:51	sdegutis	Hmm neat implementation.
13:51	rcassidy	amalloy: doesn't one use of 'for' get you what you want?
13:51	rcassidy	or am I missing something
13:52	amalloy	try it and see
13:52	sdegutis	amalloy: why is this a lazy collection?
13:52	amalloy	why wouldn't it be?
13:52	rcassidy	,(for [w [:a] x [:b :c] y [:d] z [:e :f]] [w x y z])
13:52	sdegutis	It seems like an optimization, right?
13:52	clojurebot	([:a :b :d :e] [:a :b :d :f] [:a :c :d :e] [:a :c :d :f])
13:53	sdegutis	rcassidy: yeah that was my initial solution, but I couldn't figure out how to do it with a variable number of sequences.
13:53	amalloy	rcassidy: that's fine if you have four different collections
13:53	rcassidy	ahhhhhh OK
13:53	justin_smith	rhg135: but that only works if you know ahead of time how many args
13:53	amalloy	try it with one list of lists
13:53	rcassidy	macros, maybe?
13:53	rcassidy	:p
13:53	justin_smith	err
13:53	amalloy	sure, get back to me when your macro can know at compile-time what data you get at runtime
13:53	rcassidy	hence the maybe. lol.
13:54	sdegutis	Maybe I can macro-expand the for-loop though and use the same logic in that but with variable number of sequences.
13:55	sdegutis	WHOA, never mind!
13:55	rcassidy	that's what I was thinking
13:55	rcassidy	but I'm not familiar with clojure macros yet
13:55	sdegutis	https://gist.github.com/sdegutis/953cf7cee228b755fd97
13:56	rhg135	Oh my.
13:56	rhg135	That's a lot of code
13:57	rcassidy	lol
13:57	rcassidy	yikes
13:57	amalloy	for does a ton of stuff that's either (a) for performance, or (b) for handling weirdo keywords like :let or :when in the middle
13:57	sdegutis	ahh
13:57	amalloy	if you wrote for yourself it would be slower and less expressive, but much shorter
13:58	amalloy	(exercise: implement for)
13:58	rcassidy	found some implementations with for and recur but oh man that's weird
14:01	rhg135	,(macroexpand '(defrecord X [field]))
14:01	clojurebot	(let* [] (clojure.core/declare ->X) (clojure.core/declare map->X) (deftype* sandbox/X sandbox.X [field __meta __extmap] :implements ...) ...)
14:01	WorldsEndless	Can anyone verify that you CANNOT provide contingent definitions in an :or portion of an arguments definition? (unlike let, which allows you to draw on earlier-defined values)
14:02	rhg135	Macros are awesome
14:04	WorldsEndless	Here's code that's not working; I'm probably breaking more than one Clojure rule
14:04	WorldsEndless	https://www.refheap.com/114716
14:05	WorldsEndless	Contingent :or definitions, and nested -> statements
14:06	amalloy	maps aren't ordered, sot he :or clause could get reordered
14:06	amalloy	nothing wrong with nested -> in principle, if used tastefully
14:06	WorldsEndless	Thanks for the verification. I figured
14:09	WorldsEndless	And if I don't provide an :or for some the :keys, and they go un-provided, I'll get an error?
14:15	amalloy	nil
14:16	justin_smith	~amalloy \|is\| basically a repl.
14:16	clojurebot	Ack. Ack.
14:28	sdegutis	~amalloy
14:28	clojurebot	That's the amalloy to you
14:28	sdegutis	hey the amalloy how's it going
14:29	rhg135	Is it just me, or is partial too long a name
14:29	sdegutis	rhg135: it's 7 chars longer than Haskell's version
14:30	sdegutis	About once a year I find myself thinking Haskell looks way super awesome, and then not caring anymore and going back to being productive in Clojure.
14:30	rhg135	I'm starting to think we need to reinstate the rule about haskell
14:31	rhg135	It'd be nice to have a shorter name, it'd delay the #() explosion
14:33	rhg135	It's not like having a clear name makes the meaning obvious
14:37	justin_smith	rhg135: I think if partial, identity, and constantly had shorter names we'd get complaints from newcomers and much cleaner code thanks to actually using those things more often
14:37	justin_smith	of course it's easy enough to make ones own shorter name for all of them but it's not the same is it
14:38	rhg135	(def P partial)
14:42	rhg135	There's something like that in flatland/useful
14:44	justin_smith	rhg135: regarding your earlier "wondering what the clojure/west talks will be out" the clojure/west account has been tweeting about the speakers https://twitter.com/Clojurewest
14:45	mikerod	Someone who feels strong with compiler/jvm semantics perhaps
14:45	mikerod	https://github.com/clojure/clojure/blob/master/src/clj/clojure/core_deftype.clj#L35-L36
14:45	mikerod	is this guaranteed that the class dynamically generated by `gen-interface` won't get GC'ed before the `import` happens?
14:45	hiredman	yes
14:45	mikerod	from what I can tell, only a SoftReference to that class exists
14:45	mikerod	for a very short time
14:46	mikerod	(non-AOT)
14:46	mikerod	we actually had a very hacky situation where we un-imported a Class that was created via definterface, and it actually got GC'ed on us before a JIT loaded namespace tried to import that class later
14:46	mikerod	admittedly this is not a good or common use-case. my question is specifically these 2 lines though
14:47	mikerod	To me, for these to be safe, you'd hvae to hold a local reference to the Class returned from `gen-interface` until the `import` is complete
14:47	hiredman	specifically, it is a let instead of do there to avoid the class being gc'ed
14:47	mikerod	hiredman: I was suspicious of that!
14:48	mikerod	but I have no idea why the `let` is causing a reference to be held still
14:48	mikerod	I guess I need to explore that more
14:48	WorldsEndless	I find myself writing something like, (topic-keywords :file file :model model ...) for a bunch of values. I seem to remember hearing, isn't there an easier way
14:48	mikerod	I would have expected it to need to be `(let [cl (gen-interface :name ~cname :methods ~(vec (map psig sigs)))] (import ~cname))
14:48	WorldsEndless	?
14:49	mikerod	WorldsEndless: do you mean destructruing a map?
14:49	hiredman	if it was a do, it would be a top level do, so each expression within the do would be hoisted in to its own top level form
14:49	mikerod	(let [{:keys[file model]} my-map] <etc>)
14:49	justin_smith	WorldsEndless: the solution is to never write functions that take & {:keys ...} args
14:49	justin_smith	and just use hash-maps instead
14:49	mikerod	justin_smith: good one :)
14:49	mikerod	(inc justin_smith)
14:49	hiredman	and each toplevel form, when it is compiled, basically ends up in its own function like ((fn [] form)) for reasons
14:49	mikerod	hiredman: ok, fair enough on top-level forms. However, what if GC stops the world between `gen-interface` and `import`
14:50	mikerod	can it not do that?
14:50	mikerod	maybe that is where i don't understand well enough
14:50	mikerod	perhaps there is some safety in unused return value references as long as it happens on within the same call stack frame or something
14:50	mikerod	happens within*
14:51	mikerod	I am aware that do's hoist into top-level forms though
14:51	hiredman	exactly
14:51	mikerod	interesting
14:51	hiredman	the let means it all happens within the same method
14:51	hiredman	so you have a live reference on the method stack
14:51	mikerod	yes, I was thinking the return value of `gen-interface` would still have pushed that value to the stack
14:52	mikerod	so then I thought - maybe it is still "live" from a GC point of view
14:52	mikerod	I just wasn't sure of the guarantees there
14:54	hiredman	if the gen-interace and the import where both top level forms, the return value of gen-interface would be thrown away, between forms, and that return value is the reference to the class
14:54	mikerod	yep, that makes sense
14:55	mikerod	I just didn't know that return values are safe to rely on when you don't have any reference to them right away. however, I guess that wouldn't make sense from a JVM-level since you have to push the reference to a local after it has been created
14:55	mikerod	local or global etc
14:57	mikerod	(inc hiredman)
14:58	mikerod	I guess that doesn't work anymore - or changed :P
14:58	hiredman	it is kind of precarious
14:58	justin_smith	mikerod: bot is off the job
14:58	mikerod	I see
14:58	hiredman	I would do something like (let [a (gen-interface ...)] (import ...) a)
15:00	binjured	is there a way to reference a function from another ns in a way that doesn't lose docstring and stuff?
15:01	binjured	like `alias` but for a particular function, i guess
15:01	hiredman	you are confused
15:02	binjured	usually
15:02	hiredman	so your question doesn't make much sense
15:03	hiredman	what are you doing and why do you think you are losing docstrings?
15:03	mikerod	binjured: yeah, doc strings and that sort of information is stored on the var typically if you are thinking of like (defn my-function "my docs [x] )
15:03	mikerod	so you get it from the var object, not the function #'my-function
15:03	mikerod	specifically (meata #'my-function)
15:03	mikerod	ugh
15:03	mikerod	(meta #'my-function)
15:04	binjured	just trying to provide a public api to some functions in deeper namespaces, basically
15:04	mikerod	if you want to transfer that, you can, but I'd probably use something more robust for it like potemkin
15:04	mikerod	https://github.com/ztellman/potemkin#import-vars
15:04	mikerod	Looks like Zach Tellmen had the same thoughts as you
15:05	binjured	ah, cool, thanks!
15:05	mikerod	I do like to use import-vars for a few things. mostly when we need to hide a dependency from some ns we don't want to expose publicly
15:05	hiredman	gross
15:05	binjured	haha
15:05	mikerod	hiredman: hmm, I mean you can do it yourself. however, the idea of needing to hide some of your namespaces from the public API has value
15:05	hiredman	nope
15:05	mikerod	and if you do it yourself, you'll wind up nearly at import-vars
15:06	jcorneli	hello, I have a question about how to override global variables
15:06	jcorneli	This isn't working
15:06	jcorneli	(set! print-length 10) (defmacro print-all [body] (with-redefs [print-length nil] `(do ~body)))
15:06	jcorneli	(print-all (my-function)) will only print ten items
15:06	mikerod	I have a great use-case. we have a library, we have a unbounded ton of consuming code that will use this library. if we want our consumers to use some other clj lib, like schema for example, we need to hide it behind a layer in case they make any api changes.
15:07	mikerod	otherwise we can essentially never upgrade
15:07	mikerod	because we cannot go fix every consumer of our lib
15:07	mikerod	so we want very minimal dependency exposure to these other projects
15:07	mikerod	and they are small and do not need unlimited access to the world of all clj libs
15:07	mikerod	there are times you don't want to expose namespaces
15:07	hiredman	mikerod: shuffling around names in namespaces doesn't do that
15:07	mikerod	not to mention, just general code organization and movement breaks everything
15:08	hiredman	mikerod: there is no such thing as a private namespace
15:08	rhg135	That just seems like a hack around documentation
15:08	mikerod	it isn't private, you just expose a limited view of an api that comes from elsewhere
15:08	mikerod	and you call it your own name, in case they have breaking changes
15:08	mikerod	then you move it out of import-vars and make a pass-through that deals with the breaking change in a non-breaking way
15:08	mikerod	but you have to start off with import-vars since at first, you are the same
15:09	hiredman	you are better off starting without import-vars with your own function
15:09	mikerod	allows a slower roll out of changes, whlie still allowing the dependencies to be uplifted
15:09	mikerod	that part I don't get
15:09	mikerod	it mostly transfers metadata
15:09	mikerod	I mean, we could write it. but it is a tiny lib, so why rewrite it?
15:09	rhg135	So a layer of indirection
15:10	hiredman	don't transfer the metadata
15:10	mikerod	you can have a var point to anotehr var
15:10	mikerod	then your 2 deep in calls though
15:10	mikerod	I guess that's fine
15:10	hiredman	if you are creating an api over another api, do the work and create it
15:11	mikerod	Create schema over again?
15:11	mikerod	hah
15:11	mikerod	honestly, I see very little weirdness in what import-vars is doing
15:11	hiredman	mikerod: no, you say you are carving out some specific subset
15:11	hiredman	and exposing that as a new api
15:11	mikerod	yes, like - everyone use schema stuff that we have exposed
15:12	mikerod	nothing else in case they change a name or something on us in a newer release
15:12	mikerod	(this has happened)
15:12	mikerod	and not only in schema
15:12	hiredman	if that is what you are doing, you should write functions that do that (which may call schema) with their own docstrings describing the semantics of your api
15:12	mikerod	it is identical
15:12	mikerod	so we are just copy/pasting
15:12	mikerod	import-vars = automate that
15:12	mikerod	not to mention there is an entirely different argument here
15:12	mikerod	to be said for the goals of import-vars
15:13	mikerod	that your api structure doesn't need to be your code organization structure
15:13	mikerod	I haven't really went down that path, but I think there is value in that idea
15:13	hiredman	what you have created is just a worse form of vendoring all your deps
15:13	mikerod	it is like vendoring, I'd agree with that part
15:13	hiredman	so vendor
15:13	mikerod	but I don't see the "worst" argument
15:13	mikerod	we'd rather shade it in and rename all namespaces
15:14	mikerod	so they don't conflict with consumers versions etc
15:14	mikerod	but remapping namespaces is risky in clj I'd say
15:14	hiredman	because you don't actually have your own copy of the code that you have control over
15:14	mikerod	so our consumers don't have a dep on schema at all, for example
15:14	mikerod	is how it works to import-vars over it
15:15	mikerod	so we control the version, we control introduction of breaking changes regardless of the version we pick up
15:15	mikerod	and if we use another lib, that also uses schema, and we need to get to the same version to be compatible between our lib and theirs, we can. while still not breaking our consumers
15:15	mikerod	since our consumers don't see these breaks immediately
15:16	mikerod	Perhaps there are other paths to fixing it. import-vars seemed pretty straight forward.
15:17	mikerod	and maybe it is a specialized case in general
15:17	mikerod	basically though, I was going to write similar to import-vars, then I saw it was written already and used quite a bit across other projects
15:21	hiredman	a lot of bad things are done in a lot of projects
15:21	mikerod	Ok, but I still haven't been very convinced of the pitfalls of this approach.
15:22	mikerod	I mostly gather that you don't like it and think it is weak vendoring of some sort.
15:22	mikerod	So I'm always open to good suggestions that explain the pro's and con's. I just am not hearing them.
15:22	hiredman	I think what you are doing is
15:22	hiredman	(weak vendoring)
15:22	hiredman	I don't think all uses of import-vars are
15:23	mikerod	I said I see 2 entirely separate camps of usage of it. (1) decoupling code organization from API organization.
15:23	hiredman	in generally, they seem to be the result of poor code organization, and/or the unwillingness to tackle large refactorings
15:23	mikerod	(2) isolating dependencies
15:23	mikerod	I guess you can call it unwilling, but the reality is its consumers out of "our control"
15:24	mikerod	old things have to keep working until some end-of-life
15:24	mikerod	it is always fun and nice when you can go uplift the world whenever you want, but not always practical
15:24	pullo	does anyone know why, when I 'lein deploy' to a private repository (just a folder on my local drive, different from ~/.m2), the task also creates an empty (i.e. no jar) artifact in my ~/.m2 repo?
15:25	mikerod	and the reality is, we like schema. our consuming projects should use schema. we can't risk being in conflict of versions between us and our consuming libs on schema.
15:25	pullo	I currently have to delete the empty artifact in my ~/.m2 if I want to resolve dependencies from the private repo without lein crapping out.
15:25	mikerod	going with the schema theme
15:26	hiredman	mikerod: sure, if you are committed to providing a compatible api to a legacy schema version, then commit and create a namespace with the set of functions you support, with the doc strings spelling out the semantics you support, and then call out to schema
15:27	mikerod	hiredman: so just have to do that for like 50 vars or more
15:27	mikerod	just sounds like manual work, where a machine can do it just as well
15:27	hiredman	if a schema docstring says "look at website example.org for how feature X works"
15:27	mikerod	when we have an exceptional case, a wrapper, we use our own new var to do it, with its own doc string
15:27	mikerod	we don't import-vars if we have changed it
15:27	hiredman	and a consume bookmarks that website and uses it as their reference
15:27	mikerod	that wouldn't make snese
15:28	mikerod	Ok, that is a good point on how a doc string could become misleading
15:28	mikerod	if it was specific to that version, then they don't realize other vars they are using are different
15:28	hiredman	what happens when you use whatever editors "view source" on your facade?
15:28	mikerod	although they are different namespace, so you really can't just assume they aren't different
15:29	mikerod	with import-vars, looks to jump to the original source
15:29	mikerod	I understand that your cross reference can become weird from doc strings
15:29	mikerod	that is a good point on where it has a pitfall
15:30	mikerod	"this function uses function-name-x"
15:30	mikerod	however, we don't expose function-name-x because it was a breaking change, so we still have function-name-y instead
15:30	mikerod	so you'd hvae to look at function-name-y's doc string, which would say "this is a pass through to function-name-x but left for compatibility with previous versions of lib X"
15:30	mikerod	but still, yes I could see some confusion
15:32	hiredman	unless you are truely vendoring (copying and renaming namespaces) your consumers (and any of their dependneices) could replace the version of schema on the classpath at any time
15:36	jcorneli	I'm still stuck with rebinding print-length in a macro
15:36	jcorneli	the latest non-working version I've come up with is:
15:36	jcorneli	(defmacro print-all [& body] `(do (binding [print-length nil] (do ~@body))))
15:36	justin_smith	jcorneli: what is the outer do for?
15:36	justin_smith	or the inner one, even
15:36	pullo	~'print-length
15:36	clojurebot	I don't understand.
15:37	hiredman	jonathanj: there is no call to print anything in there, why would binding print length do anything?
15:37	mikerod	hiredman: yes they can, and that would break things. it isn't consumers of arbitrary libraries int hat sense
15:37	mikerod	so yes, specialized
15:37	jcorneli	the call to print is in the body
15:37	jcorneli	or in the ~@body, rather
15:37	rhg135	justin_smith: her tweet about the talk didn't even mention that job. I think you are safe :P
15:37	justin_smith	rhg135: it's just jokes, yes
15:38	hiredman	jcorneli: what does it look like?
15:39	jcorneli	The inner function is meant to be "any code"...
15:39	jcorneli	it could be '(1 2 3 4 5 6 7 8 9 10 11)
15:40	hiredman	jonathanj: (def f (print-all (fn [] (prn (range 20))))
15:40	hiredman	then (f)
15:40	hiredman	jcorneli: there is no call to println in that quoted list
15:40	jcorneli	But print-length tells how many items to print from a list
15:41	jcorneli	Given (set! print-length 10), then (print-all '(1 2 3 4 5 6 7 8 9 10 11)) returns (1 2 3 4 5 6 7 8 9 10 ...)
15:41	jcorneli	or rather, that's what it prints to the REPL
15:41	hiredman	jcorneli: yeah, but unless a call to print is in the dynamic extent of the body of the binding the binding doesn't exists
15:42	hiredman	jcorneli: the repl prints results after they have been evaluated, not inside some arbitrary scope in the evaluation
15:42	jcorneli	ok, think I see what's going on
15:43	hiredman	think of each expression you type in to a repl as a function body, that is called, and then the repl prints the result
15:43	jcorneli	It's interesting because (defn save-local [] (binding [print-length nil] (spit "data.clj" (prn-str @node-store)))) works as expected
15:43	jcorneli	But that's not printing to the REPL but rather to a file
15:43	hiredman	nothing "prints to the REPL"
15:43	jcorneli	Well, CIDER does :-)
15:43	hiredman	the repl evaluates an expression, then prints the result
15:44	justin_smith	jcorneli: you aren't relying on the implicit print behavior there, the implicit print of the repl happens outside any of your dynamic scope
15:44	hiredman	the repl is driving the printing
15:44	jcorneli	yes, this is dawning on me now
15:44	justin_smith	unless you started said repl inside your dynamic scope
15:45	jcorneli	Thanks for the help guys
15:50	amalloy	hiredman: i would say that (print 5) is "printing to the repl", because it's printing to a out which is configured to go straight to the repl
15:51	hiredman	semantics
15:52	hiredman	"printing to the same output stream as the repl"
15:54	hiredman	if you embed some kind of repl in your app a common thing is you end up wanting to limit the printing, and that can often start out as creating a custom evaluator that sets the bindings, which is of course terrible, you should create a custom printer that sets them
15:54	hiredman	sorry, not a custom evaluator
15:54	hiredman	wrapping the whole repl in the bindings
16:16	sdegutis	What's that function again that lets you count the numbers of things in a collection, assuming there are duplicates?
16:16	sdegutis	It's some obscure word that I almost remember but can't quite.
16:17	sdegutis	occurrences?
16:17	TEttinger	distinct
16:17	sdegutis	TEttinger: That just removes duplicates without counting them.
16:17	TEttinger	maybe
16:17	sdegutis	TEttinger: The function I'm thinking of counts them. It's kind of like group-by in that sense.
16:17	sdegutis	Hmm let me look for that Clojure cheat sheet, maybe that has it.
16:18	sdegutis	frequencies!
16:18	sdegutis	Phew. Thanks TEttinger.
16:19	TEttinger	ohhh
16:20	TEttinger	yeah I was about to suggest frequencies, it didn't sound like what you wanted
16:20	TEttinger	I thought you meant #(count (distinct %))
16:20	jcorneli	justin_smith hiredman: I believe I've found a simpler solution that actually works: (defn print-all [body] (let [result (do body)] (binding [print-length nil] (print result))))
16:20	jcorneli	thanks again for the guidance
16:21	hiredman	that is nonsense
16:22	hiredman	it is trivially made simpler and better
16:23	hiredman	(let [x y] x) is just x
16:26	justin_smith	*(let [x (do y)] x)
16:28	sdegutis	hiredman: you mean y right?
16:38	sdegutis	,(let [y 2] (= y (let [x y] x)))
16:38	clojurebot	true
16:38	sdegutis	Anyway, programming is hard.
16:38	justin_smith	sdegutis: you left out the do
16:38	sdegutis	justin_smith: Correct.
16:39	justin_smith	,(do 'b (do 'b (do))) ; sinatra
16:39	sdegutis	My original CSS stuff was very incorrect, I'm trying to rewrite it to be correct, and it's a very recursive problem to solve. So I'm struggling to think recursively right now to try to figure that out.
16:39	clojurebot	nil
16:39	sdegutis	justin_smith: hahaha hhaha
16:39	justin_smith	sdegutis: I am afraid of CSS
16:40	sdegutis	justin_smith: CSS itself isn't great, but what I'm struggling with isn't inherent to CSS itself. It's just a transformation of one Clojure structure into another.
16:41	sdegutis	The input can either be a string, a hash-map, or a list containing any of these three things. The output needs to be a re-structured version of it that's not too dissimilar.
16:41	sdegutis	So my natural idea was to create a recursive function that does a cond, with list? string? and hash-map? as its only three conditions.
16:42	sdegutis	But that's where I'm stuck. When it encounters a string, it needs to "add" that to some kind of list, via a return value, which presumably appends to a collection obtained via a parameter one level up.
16:43	sdegutis	Arghh, recursion is hard.
16:44	sdegutis	Why after a decade of professional programming is recursion still so hard?
16:46	amalloy	understanding recursion is only hard because you haven't yet understood the rest of recursion
16:47	pbx	http://www.badum-tish.com/
16:48	justin_smith	amalloy: the hardest part is figuring out when you can escape learning recursion.
16:51	lockdown	sdegutis: because you didn't do "The Little Schemer"
16:51	sdegutis	amalloy: whoa
16:51	sdegutis	justin_smith: oh man
16:51	sdegutis	this is too intense
16:56	rcassidy	what step of the design recipe are you on? /s
16:58	rcassidy	(but seriously, it helps with recursion)
17:06	bendlas	Hi people, any news on the missing latest source packages?
17:06	bendlas	GET https://commondatastorage.googleapis.com/chromium-browser-official/chromium-48.0.2564.109.tar.xz 404s
17:07	justin_smith	bendlas: are you looking for google closure?
17:07	bendlas	justin_smith: ooh sorry
17:20	TimMc	rcassidy: was gonna say it but didn't :-)
17:25	xemdetia	why are we writing faces
17:25	xemdetia	sorry my brain is broken please ignore
17:30	justin_smith	xemdetia: ¯\_(ツ)_/¯
17:45	xemdetia	justin_smith, I have that as a macro in st
17:45	xemdetia	for emergencies
18:14	cortexman	what's the right / easy way to read an edn file off disk
18:15	justin_smith	cortexman: do you want the string or the clojure data?
18:16	justin_smith	for just string, slurp, for clojure data (read-string (slurp f))
18:16	justin_smith	if you don't trust the file (maybe it came from uncertain source) use clojure.edn/read-string
18:23	amalloy	if you do trust the file, use clojure.end/read-string anyway
18:27	justin_smith	yeah, I guess edn/read-string is the better one to use all around now
18:28	rhg135	for edn? yeah always
18:29	rhg135	it's kinda like reading json with eval. it technically works but eventually it'll mess you up
18:45	sdegutis	Is there some simple way to copy a string to an output stream that I'm missing?
18:46	justin_smith	sdegutis: into an existing stream or create a new one based on that string?
18:46	sdegutis	Into an existing output stream.
18:46	justin_smith	and .getBytes isn't doing it?
18:46	sdegutis	The only thing I can think of is to convert the string into a UTF-8 thing using .getBytes
18:47	rhg135	,(do (require 'clojure.java.io) (doc clojure.java.io/copy))
18:47	clojurebot	"([input output & opts]); Copies input to output. Returns nil or throws IOException. Input may be an InputStream, Reader, File, byte[], or String. Output may be an OutputStream, Writer, or File. Options are key/value pairs and may be one of :buffer-size buffer size to use, default is 1024. :encoding encoding to use if converting between byte and char streams. Does not close any streams except thos...
18:48	sdegutis	rhg135: when copy receives a string, it assumes it's a filename or URL.
18:48	sdegutis	rhg135: I'd need to convert a string into an input stream or something first to use it with copy.
18:48	rhg135	StringReader yo
18:48	sdegutis	Which isn't a half-bad idea I guess.
18:48	justin_smith	or just getBytes
18:48	rhg135	or that
18:49	sdegutis	Heck yeah I just created a zip file in Clojure.
20:02	jack_rabbit	I'm reading core.async docs. If I use >!! or <!! in a go block, what happens?
20:03	jack_rabbit	I assume it blocks the thread executing the block rather than yielding?
20:04	amalloy	justin_smith: getBytes :(
20:05	amalloy	it's fine if you need bytes, but converting from characters to bytes in order to process a string should be a sin
20:25	sdegutis	How do you write an InputStream to a file?
20:25	sdegutis	I tried (spit "filename" istream) but no luck.
20:27	rhg135	io/copy
20:28	rhg135	(io/copy in (FileWriter. name))
20:28	rhg135	io/copy is the answer. always.
20:34	sdegutis	Thanks rhg135.
20:35	rhg135	np
20:36	rhg135	I wish something like it existed for node/cljs
20:36	rhg135	but I'm not masochist enough to write it myself
20:38	sdegutis	This is so strange.
20:39	sdegutis	I'm copying from a non-empty byte-array to a file, and it's turning out an empty 0-byte file.
20:39	sdegutis	I'm baffled.
20:57	sdegutis	Okay whatever it works now good enough.
20:58	amalloy	you're probably not closing the writer
21:06	rhg135	maybe I'll write it for nashorn/cljs where it's basically a sed
21:08	justin_smith	amalloy: but outputstreams use bytes not strings
21:17	amalloy	i mean, when you have characters and you're writing to a byte-oriented stream, you need to at least consider encoding. just slapping utf-8 on it is not a solution
21:18	amalloy	you need to make sure whatever's on the other end is prepared to receive your string as utf-8, or else when you get a user in asia your io code will just break
21:21	noncom	hi!
21:22	noncom	can somebody advice a way to organize a file download in compojure?
21:22	noncom	or give a link to an example..
21:22	noncom	i can't find a working example of this
21:22	noncom	i have a byte array for the file
21:39	rhg135	if we all just used utf-8 we wouldn't have that problem, but we'd have the problem of noobs in weakly typed languages using bytes as mutable strings
21:41	noncom	i have found a solution
21:42	noncom	rhg135: huh? it's the first time i hear of that
21:43	rhg135	I saw it all the time in python2
21:43	rhg135	it had no byte type
21:44	rhg135	it was nightmare fuel
21:44	noncom	omg
21:44	justin_smith	multi-byte-character? what's that? who ever heard of such a thing?
21:45	wmealing	nobody ever.
21:45	wmealing	all those chinese people.. they never heard of it
21:45	rhg135	it's funny how much they protested at python3's sanity
21:45	wmealing	if you dont do foreign languages, its pretty easy to miss
21:45	wmealing	ie, not see the need for
21:45	justin_smith	wmealing: I mean, for a multi byte character to be needed, that would require more than 256 symbols
21:46	justin_smith	and I mean there's gotta be less than 100 symbols, total
21:46	rhg135	"we don't need no bytes! it's too hard!"
21:46	wmealing	justin_smith: :)
21:46	rhg135	"now we have to be explicit"
23:19	nikki93	do people like "clojure in action" 2nd ed?
23:39	skjljsk	https://github.com/adzerk-oss/boot-test boot test break if there is a custom source file with build tasks?
23:39	skjljsk	clojure.lang.Compiler$CompilerException: java.io.FileNotFoundException: Could not locate boot/core__init.class or boot/core.clj on classpath., compiling:(build/tasks.clj:1:1)
23:43	skjljsk	anyone else faced this?