#clojure – 2016-03-01

2016-03-01

02:54	Kneiva_	sdsd
05:07	umu-erik	Hello, I'm writing a discussion on Clojure in my beginner's level project. I've found many discussions on the advantages of Clojure but now I'm trying to find the other side of the argument. What would an example of a use case where Clojure is not suitable be?
05:10	qsys	... in an environment that's not open for 'non-Java' ;)
05:12	tdammers	umu-erik: anything where type-driven development is a serious advantage, anything hard-realtime, anything where running on JVM is out of the question, anything where you need to hire dirt-cheap developers and can afford atrocious quality, anything that needs to start up from scratch in a matter of milliseconds
05:12	TEttinger	anything where lines of code written are a metric of work done
05:12	tdammers	TEttinger: that's a subset of my last point ;)
05:13	TEttinger	hehe
05:13	tdammers	or rather the one before that
05:14	tdammers	the alternative choices in those cases, btw., would be Haskell, C or C++ or maybe Rust, Scheme or Common Lisp, PHP, and Scheme or Common Lisp again
05:15	TEttinger	also the stuff Ada is used for is a good example of what Clojure should not be used for. Ada has a lot of use in avionics (planes and military computer stuff), in part because if someone dies as a result of coding error, and that person was not INTENDED to die (an important distinction in the department of defense's fav lang), you can figure out what code did that
05:15	tdammers	yes
05:15	TEttinger	Ada is hideously verbose, but that's in part due to copious safety checks
05:15	tdammers	Ada also has a strong static type system right?
05:15	TEttinger	very
05:16	TEttinger	stronger than C or C++, weaker than Haskell
05:16	tdammers	then not "very" :D
05:16	tdammers	but "fairly" or "reasonably" :D
05:16	TEttinger	not much weaker than haskell
05:16	tdammers	I was under the impression that in terms of static guarantees it was about on par with Haskell, but less expressive and more verbose
05:17	tdammers	which, in a high-security / high-stakes environment, might arguably be a benefit even
05:17	TEttinger	it does have some neat features designed to ensure imperative code doesn't have a lot of the bugs it often has
05:17	mokuso	wow, a language can have stronger static type than C? Interesting !
05:17	tdammers	mokuso: C's static type system is so weak that it's hardly worth mentioning
05:17	tdammers	int i = "Hello, world!"; printf("%s", i); // ouch
05:17	mokuso	so, one could say that Haskell is the language with the hardest static type system ?
05:18	TEttinger	like you can have enumerated integers, that are limited to (for instance) between 1 and 100. or 0 and 99, if you want an array index
05:18	tdammers	TEttinger: that's something Haskell is painfully lacking
05:18	mokuso	tdammers: how would you write the same thing in Haskell? I can google, but hey, since we're talking .. :)
05:18	TEttinger	if you assign 100 to the 0-99 range, you loop around to 0 instead of erroring
05:19	tdammers	mokuso: you wouldn't, that's the point. It'd be something like: do { let i = "Hello, world!" :: Int; putStr i }
05:19	TEttinger	mokuso: if you want the strongest type system I'd guess Agda? there's likely something newer
05:19	tdammers	but it wouldn't compile, because the types don't match up
05:19	mokuso	tdammers: aha, thanks
05:20	tdammers	(btw, if you'd remove the :: Int type hint, it would compile, but i would be inferred as String
05:20	umu-erik	Thanks for the responses, would I be correct to assume that Clojure needs a virtual machine to interpet its bytecode. This is a strength but could also be a big weakness.
05:20	TEttinger	clojure doesn't have bytecode itself
05:20	tdammers	umu-erik: in theory, clojure could run on other backends; there's clojurescript, which compiles to JavaScript, and I believe there an implementation that targets the .NET CLR
05:20	mokuso	thanks TEttinger , I'm just being curious. I'll have a look tho
05:21	umu-erik	Doesn't AOT compilation of clojure create JVM-bytecode?
05:21	TEttinger	it can produce JVM bytecode that is essentially the same as what Java produces, though it may use the clojure libs (java can too)
05:21	tdammers	umu-erik: but in practice, most clojure projects are somehow tied into Java's library ecosystem, so while you're still using the same core language, most libraries won't transfer as-is
05:21	tdammers	unless they were designed to be backend-agnostic
05:22	tdammers	practical clojure projects can be assumed to require a working JVM
05:22	clojurebot	Titim gan éirí ort.
05:22	TEttinger	and clojurescript is pretty much a separate language, but is extremely similar
05:22	TEttinger	IIRC the macros in clojurescript use clojure to produce their final output
05:22	tdammers	TEttinger: arguably, yes. I'd call it the same language but with an incompatible standard library
05:23	TEttinger	that sounds fair, yeah
05:23	tdammers	the macro thing is kind of annoying IMO
05:23	tdammers	part of the beauty of clojure, IMO, is that macros are written in the exact same language as the code they produce
05:23	TEttinger	yeah
05:23	tdammers	so you can have a function that is used both in macro space and in code space
05:23	TEttinger	most lisps have that, right?
05:23	TEttinger	or at least schemes
05:24	tdammers	yes, that's kind of the unique selling point
05:24	tdammers	"homoiconic" being the fancy word
05:24	TEttinger	oh that's what you mean
05:24	tdammers	but in clojurescript it feels a bit second-class, because it's not 100% the same language, and there's a noticable barrier
05:24	TEttinger	I thought the "macro space/code space" thing was referring to the differences between scheme and CL
05:24	J_Arcane	hopefully that can be fixed now that CLJS is self-hosting.
05:25	mokuso	tdammers: I've seen this term before. I think in a clojure book. It's similar to the notion of isomorphism if I got it right
05:25	TEttinger	homoiconic is homo- "same" iconic "representation", to mangle the greek
05:25	mokuso	I know
05:26	mokuso	I'm Greek :)
05:26	TEttinger	hehe
05:26	tdammers	TEttinger: you mean lisp-1 vs. lisp-2
05:26	TEttinger	I can never remember what iso is in greek
05:26	TEttinger	yes
05:26	mokuso	iso stands for equal
05:26	tdammers	TEttinger: clojure/scheme, where functions are lambdas bound to variables, vs. CL, where functions live in a namespace of their own
05:26	TEttinger	oh that makes sense :)
05:27	mokuso	that's why in Greek the equation is called "isotita" :>
05:27	TEttinger	isometric is equal distance measurement, which makes total sense
05:27	mokuso	yeh :)
05:27	mokuso	isosceles , etc
05:28	mokuso	sceles stands for legs, more or less
05:28	TEttinger	I think if isomorphism is related to the term polymorphism, then homoiconic refers to something else DESPITE being made of synonyms
05:29	TEttinger	equal shape and same representation I think in this case refer to different "levels" of the language's design
05:29	tdammers	isomorphism means the same shape; homoiconic means the same symbols
05:29	mokuso	I'm not sure how 'isomorphism' is used in functional languages. I've seen it only in Graph theory, so far
05:30	tdammers	two things that are isomorphic have the same shape, despite that shape being implemented using a different set of symbols, and being filled with different content
05:30	mokuso	between two graphs that are the same, if you change the name of the nodes and the vertices
05:30	TEttinger	homoiconic in lisps refers to the same syntax being used for data and code
05:30	tdammers	for example, a structured text document and a file system are isomorphic, because they're both tree-shaped
05:31	tdammers	by contrast, homoiconic means that two things are expressed in the same symbolic representation, despite having different meanings or referring to different domains
05:31	mokuso	nice
05:31	TEttinger	that is, one uniform syntax for everything. it doesn't have to be lisp-like to be homoiconic though. APL, REBOL, a few others of note
05:31	TEttinger	I think Io is homoiconic
05:32	tdammers	for example, the form (pr 1) and the form '(1 2) are homoiconic; they use the same symbolic language (s-expressions), but one is interpreted as a function call, and the other is a list containing two numbers
05:32	tdammers	and to some degree, the term "homoiconic" is completely meaningless, because on some level, all programming languages are homoiconic
05:33	tdammers	C programs are represented as byte sequences, and they can operate on byte sequences
05:33	tdammers	which means that C is homoiconic, the symbols being bytes
05:33	tdammers	(interpreted as source code, or as byte sequences, or as 8-bit encoded strings)
05:34	TEttinger	lisp-like syntax is one of the things that clojure diverges from its roots on somewhat. using non-parenthesis punctuation like {} and [] for some data is definitely different, and it's purely for programmer benefits; there's IIRC no difference between (vector 1 2 3) and [1 2 3]
05:34	TEttinger	the use of it in destructuring has no parallel though, that I can think of
05:34	tdammers	correct, but it doesn't really change clojure's homoiconicity
05:35	TEttinger	yes, it's just a difference from how lisp does it
05:35	tdammers	yes
05:35	TEttinger	or common lisp or scheme, I guess is more accurate
05:35	tdammers	on a side note, in Scheme you can use [] and () interchangeably
05:35	TEttinger	I've been told that by people who use [] for unusual purposes in scheme
05:36	tdammers	well, "unusual"...
05:36	tdammers	usually in the context of minilanguages or certain macros
05:36	TEttinger	not usual for the scheme community in his case
05:37	TEttinger	this guy used [] around... was it macro calls? and () for anything else
05:37	TEttinger	which does kinda make sense
05:38	tdammers	I'd use [] for things that are important macrostructures (pun intended), vs. () for the nuts-and-bolts code
05:38	TEttinger	also makes sense
05:39	TEttinger	it's nice to see C# 7's proposed features being mostly FP stuff https://github.com/dotnet/roslyn/issues/2136
05:39	clojurebot	Huh?
05:40	tdammers	C# has been drifting this way for a long while now
05:40	TEttinger	yeah, it's nice and seems to be pushing java in the same direction, slowly
05:41	TEttinger	very slowly now that Java 9 is delayed another year
05:41	tdammers	god, the thought that I may have to sign up for a Java job in the near future fills me with dread
05:42	TEttinger	http://www.java9countdown.xyz/
05:42	TEttinger	only 418 days!
05:42	TEttinger	ONLY
05:42	tdammers	418 days
05:42	tdammers	I could probably design and implement a working programming language in 418 days
05:42	hyPiRion	tdammers: It's alright to use Java if you can use the library named Clojure :)
05:42	tdammers	hyPiRion: that's not the kind of job I'm talking about ;)
05:43	hyPiRion	It's not too bad if you start from scratch and doesn't need old libraries either, but that rarely happens
05:43	tdammers	well, the problem isn't so much Java the language, or the JVM; it's the kind of organisation that tends to go with it
05:44	hyPiRion	yep
05:44	TEttinger	agreed
05:44	tdammers	the kind where they've been doing straight up waterfall until 2013, then heard about this Agile thing and now they're doing Scrum wrong and in a situation that it's not suitable for in the first place, and they're still running Ubuntu 12, and getting a test server takes 3 months
05:45	TEttinger	if you use Java to code what is essentially C, it actually isn't bad at all. I've ported C code to Java and somehow managed to reduce the line count in a few cases :)
05:48	prohobo	TEttinger: is that a surfboard?
05:49	TEttinger	prohobo: the black and white A-shaped thing with a red dot in the middle is Duke, the decrepit java mascot
05:49	prohobo	ah
05:50	prohobo	but, he's a surfboard right?
05:51	TEttinger	I would have gone with a trained monkey myself. which is suitable in a number of ways, especially since java coders can often be outsourced to India, where you have a lot of wild monkeys that could potentially be writing your outsourced cheap-as-can-be code
05:51	prohobo	why not a cup of spanish coffee
05:51	prohobo	with a fedora
05:52	TEttinger	i mean a surfboard makes sense because the island of java has good surf
05:52	TEttinger	not sure what he is supposed to be
05:52	prohobo	what
05:52	prohobo	there's an island called Java?
05:53	TEttinger	yes, are you a product of the american public school system by any chance?
05:53	prohobo	canadian actually
05:53	TEttinger	aw
05:53	prohobo	how is it a burn that i dont know irrelevant geographical information
05:53	TEttinger	i was absolutely awed by how few districts teach any geography at all here
05:54	prohobo	Java looks like a nice place
05:54	prohobo	in fact, it looks like the island they used to film Jurassic Park at
05:54	TEttinger	java the island is IIRC where the kind of coffee gets its name
05:54	TEttinger	that was kauai in hawaii
05:54	TEttinger	been there
05:54	prohobo	similar landscape
05:54	TEttinger	sumatran coffee refers to sumatra in indonesia
05:55	TEttinger	where they have some funky and cool wildlife
05:55	prohobo	lemurs?
05:55	TEttinger	rhinos with red hair sticking out from under their thick hides
05:55	TEttinger	no, a bit far for lemurs
05:55	prohobo	my lack of geographical knowledge showing through again
05:55	prohobo	as far as im concerned, lemurs can be anywhere
05:56	TEttinger	lemurs are mostly found in madagascar, on the other side of the indian ocean. some can be found rarely on the african mainland. there are close relatives though, other prosimians like lorises
05:56	prohobo	i look for them
05:56	TEttinger	lorises range from cuddly looking but, I am not making this up, mildly venomous, to looking like something out of a horror movie, but not actually dangerous to pet
05:57	TEttinger	slow lorises look like cartoon teddy bears. venomous itch-causing saliva, can kill bugs
05:57	shadow6ram420	How high am i?
05:57	TEttinger	slender lorises look like slenderman mixed with some kind of bear
05:58	TEttinger	shadow6ram420: not enough. I haven't even gotten to the ocean fauna in the java area :P
05:58	TEttinger	mantis shrimp that can punch through aquarium glass with the force of a 9mm handgun
05:59	TEttinger	mimic octopuses that can change shape to imitate the silhouette of a fish
05:59	TEttinger	plus prohobo is right, it looks beautiful and tropical
05:59	shadow6ram420	so lost, or maybe for the first time... truth.
06:00	TEttinger	haha. doritos shall set you free, or something
06:00	TEttinger	I could be asleep right now for all I know, I took a sleeping pill 30 minutes ago
06:02	shadow6ram420	itchy saliva and mimicing octopie. this is the internet huh? eh.
06:02	TEttinger	haha
06:02	TEttinger	this is the one that isn't venomous, it just moves spider-like http://dharing.zenfolio.com/img/s/v-3/p587617820-3.jpg
06:02	tdammers	"relax, this one just looks like a huge spider, nothing to worry about"
06:03	shadow6ram420	omg a f-ing link i smiled inside and out.
06:03	TEttinger	this is the poisonous one, believe it or not http://www.acuteaday.com/blog/wp-content/uploads/2011/04/cute-slow-loris.jpg
06:04	shadow6ram420	i was told not to click links. or was that 4chan? idk gave someone im ip adress for tech support.
06:05	TEttinger	you can do a google image search for: slow loris
06:05	TEttinger	and see tons of em. sad stuff is when they get smuggled as pets, they usually remove teeth so they can't bite
06:06	shadow6ram420	now you want me to open another tab click a text feild input aformentioned text. kindda putting me out here arnt you? fuk it ill do it. brb
06:06	TEttinger	haha
06:07	TEttinger	30 seconds later "awwwww so cute"
06:08	shadow6ram420	so its kinda like if some kittiens were vemnous some arnt?
06:08	shadow6ram420	that thing would kill me no problem.
06:08	TEttinger	lol exactly
06:08	shadow6ram420	cuz id pick that thing up in a heartbeart.
06:09	shadow6ram420	think i like it more knowing it may be deadly(to somthing?)
06:09	TEttinger	there's only a handful of venomous mammals. one is the platypus, sometimes called the duck-billed platypus, which has a "non-lethal, wink" stabby thing on its hind legs, but only the males have it and only during some of the year.
06:10	TEttinger	it won't KILL you. but it will make you go into a coma from pain for a month
06:10	TEttinger	and it's specifically meant to stab predators who pick it up from above, like big eagles
06:11	shadow6ram420	platypus are deadly when mating, good to know. you need a show on animal planet
06:11	TEttinger	it can kill dogs, they know that from when they would shoot a platypus and send a dog to fetch its fur, find out platypus isn't dead, now your dog is
06:11	TEttinger	totally
06:12	shadow6ram420	you should watch VHF staring weird al
06:12	TEttinger	I should, it's been recommended before
06:13	shadow6ram420	badgers i didnt order any stinking badgers!
06:14	shadow6ram420	damn dual screen. now i have 25 pairs of big cute eyes looking at me.
06:15	TEttinger	and my cat https://dl.dropboxusercontent.com/u/11914692/Satchmo_Portrait.png
06:15	shadow6ram420	was tempted to check out platypus but i feel the moment has passed.
06:15	TEttinger	i'm typing at an awkward angle because my cat stole my chair
06:16	shadow6ram420	oroin's belt?
06:17	shadow6ram420	MIB reference nm
06:17	TEttinger	i wish. it does jingle though
06:18	TEttinger	best picture I have of him I think, at least recently. he was entranced by the dangling headphone cables that I knocked partway off the table, that's why his eyes are so wide
06:18	shadow6ram420	still looking at the same 25 img's
06:20	prohobo	seriously?
06:20	prohobo	a platypus can put me in a coma for a month?
06:20	prohobo	ahahahhaha
06:21	prohobo	that makes them so much better
06:33	TEttinger	prohobo: it isn't the poison that puts you in the coma though. when you get to a hospital with a platypus sting, you're screaming from the most intense pain imaginable. so they inject morphine, does NOTHING. they could give you all the morphine they have, won't change the pain. they put you in a coma to prevent you from going crazy from pain
06:33	TEttinger	or screaming all the patients away
06:33	prohobo	dude, thank god i haven't met a platypus up to now
06:33	prohobo	i'd try to hug it or something
06:33	TEttinger	they're cuddly yes
06:34	TEttinger	females never have the spurs
06:35	prohobo	more painful than a bullet ant?
06:35	prohobo	doubtful
06:37	TEttinger	much more. the poison's only effect is pain
06:37	TEttinger	it targets pain transmitters directly, bypassing the receptors
06:38	TEttinger	so morphine targets receptors
06:38	TEttinger	big whoop to platypus venom!
06:39	prohobo	that's insane
06:39	prohobo	we should build an army of platypuses
06:40	TEttinger	haha
06:40	TEttinger	it's being researched as a way to treat people who are also experiencing pain but strong painkillers don't help
06:41	TEttinger	if you can figure out how platypus venom bypasses receptors and CAUSES pain in transmitters, you could do the opposite and STOP pain in transmitters
07:31	aurelian	need to host a small ring/compojure app (no db required yet) is heroku the best free option? are there any alternatives?
07:40	justin_smith	aurelian: you can use beanstalk on aws free tier, iirc. And it's easy to deploy an uberwar on beanstalk.
08:13	solatis	okay, so i have two sequences, and i want to iterate over both of them, in nested loops
08:13	solatis	what is the function i would be looking for for this?
08:13	solatis	is it zip?
08:14	justin_smith	solatis: for
08:14	justin_smith	or doseq, depends if you want a return value or side effects
08:14	justin_smith	,(for [a [1 2 3] b [4 5 6]] [a b])
08:14	clojurebot	([1 4] [1 5] [1 6] [2 4] [2 5] ...)
08:15	solatis	yes i want a return value -- basically, i want to iterate over both sequences, call a function, and get a one-dimensional sequence back with the results
08:15	justin_smith	that's for
08:15	solatis	awesome
08:15	justin_smith	,(for [a [1 2 3] b [4 5 6]] (* a b))
08:15	clojurebot	(4 5 6 8 10 ...)
08:17	justin_smith	,(for [a [1 3] b [5 7]] (* a b))
08:17	clojurebot	(5 7 15 21)
08:28	aurelian	thanks justin_smith... my connection dropped :\
08:28	aurelian	will check that beanstalk out
08:29	aurelian	where do you get aws free tier?
08:31	Kneiva	aurelian: https://aws.amazon.com/free
08:31	aurelian	cheers! I already have an aws account and paying for some s3 stuff afair, I guess I'll need to signup with another email or something
08:33	Kneiva	aurelian: I'm using https://www.openshift.com for a small python site. The free part does not expire after a year and you don't even need a credit card.
08:34	Kneiva	Reading from their forums a Clojure application should work as well.
08:34	aurelian	cool, I'll check it out
08:34	codefinger	aurelian: are you have problems with heroku?
08:35	aurelian	nope, just asking for alternatives
08:35	aurelian	as far as I remember heroku didn't keep my app warm, so usually first request was taking foreever
08:36	Empperi	that isn't actually a heroku problem
08:36	Empperi	that happens with normal virtual servers too
08:37	aurelian	that's depends on the provider I guess
08:37	Empperi	operating system kernels tend to move idle applications to virtual memory so that more active applications have more physical memory available
08:37	aurelian	I see
08:38	Empperi	it happens with actual physical servers too
08:38	Empperi	so if your app does nothing and you wait long enough it'll end up in virtual memory
08:38	Empperi	and when it receives activity then it'll be moved back to physical memory if there's enough space left
08:38	codefinger	aurelian: heroku puts free apps to sleep if it's not being used (i.e. receiving requests)
08:38	aurelian	that :)
08:39	Empperi	that should cause even longer pauses
08:39	Empperi	but anyway, that "first request takes forever" is a more general problem
08:39	Empperi	I've had some funny talks with some guys who have been banging their heads to the wall because of that problem
08:40	Empperi	and the problem goes away with a simple monitoring script which one should have in place anyway :)
08:41	codefinger	yea, general warm-up is a java thing. many java shops spend several minutes warming up a process before bring it online
08:42	codefinger	i've heard of financial firms that execute bogus stock trades in the morning before the markets open, knowing they'll fail, but they warmup all the right parts of the app that way
08:42	Empperi	it's a thing in any JIT
08:42	Empperi	but that is a different problem
08:43	Empperi	that is about JIT optimizations which can be done only when the application is actually ran
08:44	Empperi	Clojure actually benefits hugely from JIT, it might hit it's default inlining values pretty quickly
09:06	AdmiralBumbleBee	So what is the preferred non-emacs environment for clojure these days?
09:07	ridcully	cursive or vim-fireplace ?
09:07	aurelian	I have great success with vim, but that's because I'm using vim since 2006
09:08	aurelian	atom with proton looked also nice
09:08	AdmiralBumbleBee	I'm currently trying an experiment to not use emacs for a month, as I really overrely on it
09:08	aurelian	and cursive they say is's awesome
09:08	AdmiralBumbleBee	and I need to get my clojure environment back up
09:08	ridcully	http://blog.cognitect.com/blog/2016/1/28/state-of-clojure-2015-survey-results look for "primary development environment" if you want to go with popular vote
09:08	schmir	AdmiralBumbleBee: I've heard good things about spacemacs :)
09:09	qsys	tux-vum here
09:09	AdmiralBumbleBee	schmir: I'm trying to avoid the whole emacs at all thing.
09:09	ridcully	i use vim too
09:09	qsys	*tux-fim
09:09	qsys	*tux-vim - damn'd, typing is hard today :p
09:09	Empperi	Cursive is great but it has one big drawback: macros
09:10	Empperi	I love Cursive but if your clojure programming style is heavily relying on macros then you are pretty much screwed with Cursive
09:10	AdmiralBumbleBee	Empperi: Why? because I am..
09:10	Empperi	however I hear it'll have some improvements in the near future
09:11	Empperi	AdmiralBumbleBee: Cursive doesn't use REPL for syntax evaluation thus it doesn't understand macros which need to be executed to make any sense out of them
09:11	Empperi	it uses static analysis
09:11	AdmiralBumbleBee	Empperi: that sounds not very good.
09:11	Empperi	both approaches have their benefits
09:13	AdmiralBumbleBee	I suppose I'll try Cursive and encounter any issues on my own
09:14	AdmiralBumbleBee	It looks to be the type of program I'm looking to experience by avoiding emacs for a while
09:14	qsys	once I crossed euh... lighttable
09:15	qsys	you might like that one, I don't know.
09:56	phorse	how are file downloads typically handled in a SPA? Ajax is giving me a bunch of guff.
10:01	justin_smith	phorse: so you are trying to get files via Ajax?
10:05	amoe	is there any predicate for datetimes returned from clj-time? or should I just test with 'instance?'
10:12	phorse	justin_smith: that's right - a simple crud setup - fetch from database, write to csv/xlsx, allow clients to download file
10:13	phorse	I'm using re-frame, but I feel like I'm really fighting when it comes to file uploads and downloads
10:14	justin_smith	phorse: why does the file have to exist on your server, why not send the bytes to the client?
10:14	phorse	justin_smith: I haven't explored that, where can I look to learn more?
10:14	justin_smith	phorse: in my cljs / reagent app we generate a "file download" 100% in frontend code, by crunching the data in the app state
10:15	justin_smith	phorse: one moment, let me see if I can find a good example or summarize what we do in our (closed source) code
10:16	phorse	Thanks! Some of these downloads are pretty big, though - up to 1 MB
10:16	justin_smith	phorse: but the high level version is that the file doesn't have to exist as a "file" anywhere in order to be a download, all you need is to generate the right bytes and then offer it to the user and label it as a download
10:17	renl	hi when i see a #+clj in the source code what does it mean?
10:17	justin_smith	renl: it's a cljx file, which is deprecated
10:17	renl	does #+ mean anything in clojure syntax?
10:17	renl	oh mmm
10:17	justin_smith	no, it's a special cljx directive, the cljx preprocessor will take that file and generate a clj file and a cljs file
10:18	justin_smith	but since cljc is in clojure.core, cljx is pretty much over
10:19	renl	okie thanks
10:20	phorse	justin_smith: that would simplify a lot. Do you use something like data.csv to order things on the frontend?
10:20	justin_smith	phorse: basically you end up with something like [:a {:href (str "data:attachment/" filetype "," encoded)} :target "_blank" :download (str filename "." extension)} "Download"]
10:21	justin_smith	phorse: we use testdouble.cljs.csv
10:21	justin_smith	in the above "encoded" is the actual csv data shoved into the URL
10:21	justin_smith	there's other ways to do that, but that worked out OK for our CSV (~1000 rows usually)
10:21	justin_smith	oh, and we used (js/encodeURIComponent data) to make encoded
10:22	justin_smith	and data was the outptu of the csv/write-csv call
10:23	phorse	justin_smith: thanks for walking me through that - I'll experiment with that this morning.
10:24	justin_smith	phorse: here's some docs on dataurls http://dataurl.net/#about
10:26	justin_smith	phorse: instead of data urls of course you can generate the data on the backend in a request handler, but the same concept applies - you tell the client it's a file, and just generate the content when they need it
11:27	justin_smith	I just had a random editor movement idea that probably isn't unique and might even exist
11:28	justin_smith	a keypress to move "forward by forms at this level"
11:28	justin_smith	which would mean not jumping down into lower nestings, and alwas leaving your cursor in a place so it would continue moving forward by forms of that level (if possible)
11:30	justin_smith	so if you have (defn ^f [] (x) (y) (z (+ 1 1))) moving forward would give you (defn f ^[] (x) (y) (z (+ 1 1))) then (defn f [] ^(x) (y) (z (+ 1 1)) then (defn f [] (x) ^(y) (z (+ 1 1))) etc.
13:25	cortexman	anyone using emacs/cider ? the stack traces could use some work...
13:37	amalloy	justin_smith: you mean C-M-f?
13:38	amalloy	(bound to forward-sexp)
13:38	justin_smith	amalloy: oh, does it actually do that? I guess I don't use it
13:38	amalloy	it's probably my most-used sexp movement command
13:44	amalloy	the ones that i much more rarely remember to use are paredit-forward-down, paredit-backwards-up, and so on
13:45	amalloy	i mostly only use those for defining keyboard macros
13:59	cortexman	is there a way to get the repl to respond to interrupt signals faster
13:59	cortexman	i don't care if it comes at a performance cost during debugging
13:59	cortexman	when i do C-c C-c, i need it to stop.
15:40	justin_smith	cortexman: is this because it's crucial that the process stop? because if it is about being able to access the prompt again you can just make another repl connection, since C-c C-c can only interrupt the top level process in a particular repl
15:53	Shayanjm	justin_smith: sorry for bugging you about this again - the looping process to consume messages from kafka using clj-kafka... how does that work precisely?
15:53	cortexman	justin_smith, i will try that
15:53	Shayanjm	I create a consumer c outside of the looping process, and (def msgs (messages c "test")). Intuitively I would think I could just throw (take 1 msgs) into a (while true) and append the output to some atom
15:54	Shayanjm	but I guess also intuitively that causes my REPL to hang and be generally useless
15:54	Shayanjm	how do you handle this?
15:55	j-pb	future
15:55	cortexman	justin_smith - do you use emacs / know how to make a second repl connection?
15:55	j-pb	Shayanjm: (future (something that blocks
15:55	j-pb	starts it in a new thread
15:55	j-pb	don't deref that future though otherwise you'll block again
15:55	Shayanjm	j-pb: the above was wrapped in a (future)
15:56	justin_smith	Shayanjm: the way I ended up doing it was using create-message stream, getting an iterator from that, and looping on .message calls
15:56	justin_smith	err, looping .next, and calling .message on each result
15:57	justin_smith	so pretty much not using the higher level clj-kafka stuff
15:57	Shayanjm	ah gotcha
15:57	justin_smith	iirc I made this choice because clj-kafka was providing a lazy-seq and I wanted something more explicitly stateful to connect to core.async
15:57	justin_smith	something about push vs. pull semantics and plugged up messages
15:58	Shayanjm	yeah, and I'm not sure how to pull from that lazy seq in a 'nice' way that won't hang
15:58	Shayanjm	https://gist.github.com/shayanjm/6301cad1d64191b8ecad
15:58	Shayanjm	this is currently crashing my repl
15:58	justin_smith	well, .next hangs too
15:58	justin_smith	that's the point, it hangs until you get another result from the other end
15:58	cortexman	hmm, @justin_smith, i used M-x cider-connect to connect to the existing repl server, went into the same namespace as my other repl connection, and i could not access the variables i had defined there
15:59	justin_smith	cortexman: are you sure you were in the same namespace? because that contradicts everything I know about clojure namespaces
15:59	j-pb	Shayanjm: I don't she how that should hang except for overloading the repl process as long as that future isn't referenced
16:00	justin_smith	j-pb: it will block until there's a message to read
16:00	j-pb	justin_smith: yeah but it shouldn't block general repl execution
16:00	justin_smith	j-pb: these are two conversations
16:01	justin_smith	brb, interviewing a potential hire
16:01	j-pb	justin_smith: I think "this is currently crashing my repl" was in reference to that code though
16:02	j-pb	Shayanjm: btw the same could proably be achieved by doing (future (doall (map #(swap! message-log conj %)) msgs)))
16:02	Shayanjm	j-pb ah you're right
16:03	j-pb	Shayanjm: what do you mean with "crash repl" btw?
16:03	Shayanjm	I'm currently in emacs cider so I haven't tried this in the proper terminal repl yet
16:03	Shayanjm	but
16:03	Shayanjm	when I create that future, the repl slows down until I simply can't run anything anymore
16:03	j-pb	loool
16:04	Shayanjm	(println "hi") simply doesn't execute after creating that future
16:04	j-pb	ahem how many messages do you have in there?
16:04	Shayanjm	not even that many
16:04	Shayanjm	probably like 500-1k stacked up so far?
16:04	j-pb	maybe the GC is going crazy?
16:04	Shayanjm	could be
16:05	Shayanjm	maybe I need to be running this on a heftier host...
16:05	cortexman	justin_smith i just confirmed that's the behavior i'm getting
16:05	Shayanjm	oh yeah
16:06	Shayanjm	j-pb: OutOfMemoryError GC overhead limit exceeded
16:06	Shayanjm	rekt
16:09	j-pb	Shayanjm: I think the best way to go right now is using the new kafka 9 consumer direclty
16:09	j-pb	it has some really nice improvements
16:09	Shayanjm	I don't even know how I'd go about doing that in Clojure honestly
16:09	j-pb	java interop
16:09	j-pb	works super easiy
16:10	j-pb	object.method(foo, bar)
16:10	j-pb	(.method object foo bar
16:10	j-pb	)
16:14	Shayanjm	ah right
16:14	Shayanjm	okay sweet, i'll check it out
16:15	j-pb	Shayanjm: it makes it possible to access offsets manually more easily
16:21	cortexman	what's this thing APersistentMap$ValSeq
16:21	cortexman	and how can i get the val:)
16:21	TEttinger	cortexman: looks like the return of vals
16:22	TEttinger	,(vals {:a 1 :b 2})
16:22	clojurebot	(1 2)
16:22	TEttinger	,(class (vals {:a 1 :b 2}))
16:22	clojurebot	clojure.lang.APersistentMap$ValSeq
16:22	cortexman	i see. thanks
16:22	TEttinger	it is as you would expect a sequence of possibly more than one va;
16:22	TEttinger	val
16:23	TEttinger	but you can go through it with map or filter, etc.
16:23	TEttinger	,(map inc (vals {:a 1 :b 2}))
16:23	clojurebot	(2 3)
16:24	TEttinger	,(filter zero? (vals {:a 1 :b 0}))
16:24	clojurebot	(0)
17:29	WorldsEndless	I need leiningen to perform a "lein clean" every time before "lein uberwar". Is there something I can put in my project.clj for this?
17:36	cortexman	i'm trying to do (vec (concat (for [...] {}) {})) resulting in a vector of dictionaries where most were generated by the for loop, but the final one was not
17:38	cortexman	my final dictionary gets converted into vectors
17:43	justin_smith	cortexman: that's because you are calling concat on a hash map
17:43	justin_smith	cortexman: perhaps you want (concat (for ...) [{}])
17:44	justin_smith	,(concat [:a :b :c] {:a 0})
17:45	clojurebot	(:a :b :c [:a 0])
17:45	justin_smith	,(concat [:a :b :c] [{:a 0}])
17:45	clojurebot	(:a :b :c {:a 0})
17:45	justin_smith	I think you want the latter
17:47	cortexman	thanks:)
17:48	justin_smith	cortexman: also if you can prove that two connections to the same nrepl server see different namespaces (other than user I guess?) that would be a big bug in clojure.core
17:48	justin_smith	it could be that ns user is handled differently though
17:53	cortexman	i tried ns user, but i also tried another namespace
18:37	tolstoy	WorldsEndless: You can use an alias: :aliases {"uwar" ["do" "clean" "uberwar"]} or something like that.
18:43	justin_smith	tolstoy: WorldsEndless: oh, I didn't see that question. What you want is :prep-tasks
18:43	justin_smith	thses are run in order when doing an uberjar
18:44	justin_smith	well, if you add :prep-tasks to the :uberwar task, etc.
18:44	justin_smith	each profile can have its own prep-tasks definition
18:46	justin_smith	my prep-tasks for uberjar are basically ["clean" ["shell" "compile-less-files"] ["shell" "get-git-tag"] ["cljsbuild" "once" "app"] "compile"]
18:47	tolstoy	Ah, cool. I sure hope I remember :prep-tasks a year from now when I need it! ;)
18:48	justin_smith	haha
18:49	justin_smith	it's in lein help sample
18:49	tolstoy	Yes, but if you don't even know to look for it, you'll never see it.
18:49	justin_smith	tolstoy: "I need to do something when compiling" "there's an example in lein help sample" are sufficient to find the info in a minute or two
18:51	tolstoy	Just looked at it, and the examples "compile protobuf" or whatever (coffeescript, say) seems clear, but it never occurred to me to put a clean there.
18:52	justin_smith	it's almost a bug that it doesn't clean when doing an uberjar anyway, but it's easy enough to work around with a prep task
18:52	tolstoy	Yeah, it might just be an uberwar thing, or perhaps he has other generated artifacts.
18:53	tolstoy	Talk about "confusing": There's this DEQ cert you have to get for DMV in Portland, so you go to the site, type in your address, and it says I'm "inside the VIP boundary". Does that mean I need it, or not?
18:53	tolstoy	I feel like one of those TV actors who says at the beginning of every episode: It's never easy.
18:54	justin_smith	it just means you are important
18:55	tolstoy	Not Very Ignorant Peon?
19:10	tolstoy	Ah. Vehicle Inspection Station.
19:11	tolstoy	I bet the conversation over on Slack isn't this scintillating and off topic.
19:12	rhg135	~slack
19:12	clojurebot	Excuse me?
19:13	rhg135	I forget the syntax
19:43	Guthur	I recently updated my cider and it now seems to be font locked on clojure functions
19:43	Guthur	any ideas how to turn this off?
19:48	Guthur	thankfully this only seems to be the case in the REPL
19:54	cortexman	any idea on this? Caused by: java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: :db.error/not-a-data-function Unable to resolve data function: {:blah/blerg .....}
19:56	justin_smith	cortexman: is this a datascript error, maybe datomic?
20:00	cortexman	datomic yes
20:00	cortexman	i am trying to transact a vector of maps
20:01	tolstoy	cortexman: I've gotten that a lot. It's something simple, I think, like not passing the DB param or something.
20:06	cortexman	hmm.
20:08	tolstoy	If d/transact, it might be something like (d/tramsact conn [{:db/id 23 :other/attr "blah"}]) ;; missing the "conn" param, or not putting the values in a vector.
20:08	tolstoy	In other words, it's not the data, but something at issue with passing it in (at least when I get that error).
20:08	tolstoy	Or misspelling transact as tramsact. ;)
20:17	cortexman	i think the prob is i have to specify :db/add
21:00	celwell	Hello, I have a macro printing out a sexp an then the time it takes to eval (think: simple profiler). But for some reason it always wraps the sexp in an extra () when printed. Also, any advice on the macro in general?
21:00	celwell	(defmacro time-it [& body] ('do (println body) `(time ~@body)))
21:02	hiredman	,((fn [& body] (prn body)) 1 2 3 4)
21:02	clojurebot	(1 2 3 4)\n
21:04	celwell	hmmm, that's not quite the same behavior. I'm trying to print out the sexp as is (before evaluation). I.e., the code.
21:05	celwell	Here's a use case: (time-it (+ 100 (rand-int 100)))
21:06	celwell	Current macro gives: ((+ 100 (rand-int 100)))\n"Elapsed time: 0.083534 msecs"
21:06	hiredman	,((fn [& body] (prn body)) '(foo))
21:06	clojurebot	((foo))\n
21:08	celwell	then I would have to prepend a single quote every time I use it. also it doesn't call (time) on the body, which might be harder to do without a macro
21:09	hiredman	look, I think you are missing my point
21:09	hiredman	[& foo] in function arg lists in varargs syntax, it is all the arguments collected in a sequence
21:09	hiredman	so in your macro body, is all the arguments collected in to a sequence
21:10	hiredman	you pass it one thing, so body is a sequence containing that one thing
21:11	celwell	oh yeah... thanks. so maybe: (defmacro time-it [& body] ('do (apply println body) `(time ~@body)))
21:15	hiredman	you are printing the body at macro expand time, not run time
21:15	hiredman	and your macro expands to something like ('do nil (time ...))
21:16	hiredman	err
21:16	hiredman	(time ...)
21:16	hiredman	because at macro expand time you are looking up the symbol 'do in the result of the println (which is nil)
21:16	hiredman	and returning `(time ~@body) if no result is found