#clojure – 2015-12-25

2015-12-25

00:05	TimMc	TEttinger: Rodents have pretty mean bites, yeah.
00:06	TimMc	oooh, and merry Christmas
00:06	TimMc	I should go to bed.
00:06	justin_smith	I once got jumped by a squirrel
00:06	justin_smith	it lived in a warehouse were I worked, and was semi-tame
00:06	TEttinger	merry ratmas
00:06	sohail	thanks justin_smith, sente looks pretty good
00:06	justin_smith	sohail: it's been pretty easy to use
00:06	justin_smith	as long as you are OK with some core.async to hitch it all up, it works very nicely
00:11	TimMc	justin_smith: Raynes said he doesn't plan on deleting the site, or at least not the data. Phew. But it is going read-only.
00:12	justin_smith	ahh, I must have misread or misremembered
00:13	TimMc	I'm still backing up those pastes. :-P
00:24	justin_smith	TimMc: that's good - it would be cool to have it searchable by function too
00:25	TimMc	Search wouldn't cover the private pastes.
00:28	TimMc	Grabbed 5303 unique pastes. ^_^
00:30	justin_smith	TimMc: sure, but you can't back up private pastes can you?
00:49	TEttinger	5303 pastes eh? I'm compressing a large amount of PNG files again. it seems to be done with 736K files so far
00:49	TEttinger	2.3 GB processed
00:49	TEttinger	not even a third of the way done
01:02	kenrestivo	bikeshed time: this double assoc bothers me https://www.refheap.com/113128
01:03	kenrestivo	double assoc-in anyway
01:03	justin_smith	kenrestivo: #(if % (inc %) 1) is (fnil inc 0)
01:03	kenrestivo	fnil, thanks!
01:03	justin_smith	,((fnil inc 0) 1)
01:03	clojurebot	2
01:04	kenrestivo	yeah, i remember it, i'd forgotten
01:04	justin_smith	,((fnil inc 0) nil)
01:04	clojurebot	1
01:06	kenrestivo	the double update-in still bothers me tho
01:06	justin_smith	kenrestivo: maybe something like (update k (comp #(merge % m) update) :count (fnil inc 0))
01:07	justin_smith	that's weird though
01:07	kenrestivo	it is awkward
01:07	kenrestivo	but concise
01:07	kenrestivo	meh, i guess my double thing is at least easier to read and reason about
01:07	justin_smith	and it nests the ops so the k doesn't get replaced twice
01:08	justin_smith	but yeah
01:08	justin_smith	kenrestivo: there's no rule that says you can't write a proper function for update
01:09	kenrestivo	true, then i could also eliminate the useless merge: in cases where count> 1, the m is the same
01:09	kenrestivo	but my bikeshed limit is reached on this :)
01:10	kenrestivo	i'm avoiding reading a bunch of javascript docs on react
01:10	justin_smith	hah
01:10	kenrestivo	it's funny, i have a bunch of clojure projects that i've dropped at the moment where i have to dive into some other language, because at that point is ceases being fun
01:11	justin_smith	where the clojure project made you need to dive into another language?
01:11	kenrestivo	every single one that deals with the real world :p
01:12	kenrestivo	because the real world is made of java and javascript and css and c and such.
01:12	kenrestivo	to answer your question, i've been messing around with reagent, which is pretty nice.
01:13	kenrestivo	i've come up against a block with how props and such work, so i have to read react docs
01:13	TEttinger	kenrestivo: you need a lisp machine
01:13	kenrestivo	heheh, yeah, the computer museum here has a symbolics
01:14	TEttinger	there's a dude working on one that runs on a beaglebone black (small raspi-like ARM computer)
01:14	kenrestivo	cool. link?
01:14	TEttinger	no idea how far he is on it
01:14	kenrestivo	i have a beaglebone black sitting here
01:14	TEttinger	oh sweet
01:14	kenrestivo	they're great little embedded boards
01:16	justin_smith	I've got a beagle bone black around here somewhere
01:29	TEttinger	I have uh... a tronsmart MK908
01:30	ben_vulpes	kenrestivo: how did you come to be using props with reagent?
01:31	kenrestivo	i want to use :component-did-update, and that requires dealing with props
01:31	ben_vulpes	ah.
01:31	ben_vulpes	what's the story in the code side driving use of :component-did-update?
01:31	ben_vulpes	not that i don't believe that you need it, i'm just trying to peer down the road a bit and get out ahead of any leaky abstraction pain
01:51	kenrestivo	there are a few abstractions: props, lifecycle functions, atoms, and cursors.
01:52	kenrestivo	i get atoms, i think i understand cursors, and the lifecycle functions are similar to other frameworks that have those. it's just props that have me confused.
01:58	kenrestivo	:component-did-update seems to require props
01:59	kenrestivo	i'll play around with it tomorrow. it's probably straightforward, i just haven't seen it explained yet.
02:40	ben_vulpes	i have no idea about cursors man
02:40	ben_vulpes	atoms are enough for me at the moment
02:49	tolstoy	component did update is for when the component gets new "state". You might want to do something as a consequence, perhaps directly to the dom, or drop something in a channel, or whatever. You get the old props and the new props. But "props" in OM is the basic state that triggers rendering. Something like that, anyway.
02:49	tolstoy	I do think it's an "opportunity" to re-think stuff.
02:50	ben_vulpes	tolstoy: so diddling props directly will also trigger a re-render?
02:51	tolstoy	Oh, I think I might have used it to update "component local state" based on changes.
02:51	tolstoy	ben_vulpes: I don't think so.
02:51	tolstoy	They're immutable.
02:51	ben_vulpes	kk
02:51	ben_vulpes	i'm avoiding component local state like the plague
02:51	tolstoy	But you can get the old and the new and compare the two.
02:51	ben_vulpes	how do you use that and still get interactive development?
02:52	tolstoy	Local state or component-did-update?
02:53	tolstoy	When I used local-state (om.prev) it was for forms, mostly. I didn't care if things got cleared out with Figwheel, or whatever.
02:57	ben_vulpes	local state
02:57	ben_vulpes	ah
02:57	ben_vulpes	yeah that drives me a bit batty
02:58	tolstoy	This app I have now, I just have a :form key in my app-state. When I switch to a form, I clear it. Then the component reconfigures it as necessary.
02:59	tolstoy	I never have more than one form at a time, so ... it feels like a register in assembly programming.
03:00	tolstoy	Feels kinda like a dynamic-var, but in a single-threaded, single-user app, it turns out to be far less spaghetti than anything else.
04:07	geirby	hey there. what is the best leiningen cljs template to start with? With figwheel and stuff?
04:08	ridcully_	the figwheel one
04:37	geirby	ridcully_ oh, ok, makes sense :) thanks
08:27	TimMc	justin_smith: I can back up private pastes because I have their URLs, but I wouldn't want to index them -- some of them probably came from privmsg sessions.
08:31	TimMc	justin_smith: Maybe I misunderstand private pastes, though.
09:36	j-pb	how would you deal with a cyclic deftype dependency? declare doesn't seem to work
09:37	j-pb	I have a deftype A which might return objects of deftype B. However, B holds a reference to A and I'd like to type-hint it.
10:39	justin_smith	j-pb: hint the protocol it implements, not the type
10:41	j-pb	justin_smith: you can't type hint protocols afaik
10:41	j-pb	or you mean put the type into the protocol?
10:50	sohail	justin_smith: what's the difference between the websocket impl for sente and http-kit?
10:51	sohail	ah it's server-side only, I think.
10:54	justin_smith	sohail: sente uses http-kit's websockets
10:54	justin_smith	it's an abstraction
10:55	sohail	it's so straightforward
11:07	justin_smith	j-pb: sorry, still waking up. If you call the protocol methods that the deftype implements, you don't need type hints on those calls.
11:07	j-pb	justin_smith: yeah, that's a good point :)
11:07	justin_smith	j-pb: if you absolutely need to type hint usage of each type inside the other, use extend / extend-type to add the methods after both are in scope
11:08	j-pb	I don't really get sente
11:08	j-pb	's api though
11:08	j-pb	I'd either go with callback only or channel only, but it has this weird mix
11:08	justin_smith	j-pb: it gives you some handlers that set up the websocket / ajax fallback, and some channels that give you core.async messages, and functions to send to the other side
11:09	justin_smith	j-pb: you only need to use one - I never use the callbacks myself
11:09	justin_smith	(though I have code I could simplify if I used the callback feature...)
11:10	j-pb	justin_smith: sending is done though a funciton though
11:11	justin_smith	yes
11:11	j-pb	this could also be a channel
11:11	justin_smith	nothing stops you from implementing that channel
11:12	justin_smith	but really on a root level it needs to be a function, and has no need to be a channel, so it's a function
11:12	justin_smith	it's already async
11:44	sohail	Is there some reason why this lein configuration does not seem to use my handler? http://pastebin.com/VuskVAZz
11:45	sohail	weird thing is even if I include a typo in server.clj and type 'lein compile', I don't get any error messages which seems to be a symptom of something more messed up
11:45	justin_smith	sohail: why are you asking figwheel to run your handler?
11:46	sohail	justin_smith: I want to be able to debug the client and server in concert
11:46	sohail	so I just want one server running
11:46	justin_smith	OK, that might work, but I've never done it that way
11:47	justin_smith	I wouldn't be surprised if it worked perfectly; I also wouldn't be surprised if it didn't work at all
11:47	sohail	well... it's clearly NOT working :) how do you do it?
11:47	justin_smith	sohail: I start up a normal server, and let figwheel do its own thing
11:47	justin_smith	I don't need to debug the figwheel server
11:47	justin_smith	it's already a finished product
11:47	sohail	what about the cljs repl?
11:47	justin_smith	figwheel
11:48	sohail	what does your project.clj look like?
11:48	justin_smith	sohail: can't share it, sorry.
11:48	justin_smith	I start lein figwheel, I start my webserver, then I go to the page in the browser and my cljs code connects to the figwheel server
11:48	sohail	do you use emacs?
11:49	justin_smith	yes, but no repls inside emacs
11:49	sohail	ah that's probably it then
11:50	sohail	so you do lein figwheel in one window and lein ring server-headless (or whatever) in another
11:50	sohail	?
11:50	noncom	sohail: i do just that
11:50	justin_smith	sohail: yes
11:50	noncom	never had to type anything into the figwheel repl really
11:50	justin_smith	sohail: in my case I run lein repl, and start the server inside the repl
11:50	sohail	but that sweet repl and code completion
11:51	noncom	i guess first you have to justify using figwheel repl?
11:51	noncom	an interesting topic for me, since i never found a use in it
11:51	noncom	so i'd like to know
11:51	noncom	if you do
11:51	sohail	the code completion works inside emacs
11:51	noncom	ah i see
11:51	noncom	i don't use it then
11:52	noncom	turneds out it was not essential
11:52	noncom	but of course, it's nice to have i guess..
11:52	justin_smith	sohail: I've never seen someone try to run their own handler from the figwheel process. Not that it can't be done, but I definitely have not seen it.
11:52	sohail	I've never actually used code completion before, but having eldoc work is helpful.
11:53	sohail	justin_smith: I was just reading the docs. I'm probably doing something wrong
12:01	sohail	justin_smith: FYI the "chestnut" runs both the web server and figwheel in the same repl
12:01	sohail	the chestnut template, just tested it and it worked. Now to understand it.
12:30	sohail	ah I see they use profiles to execute stuff in the repl to do the work. Works for me.
12:31	pigoz	hello I am kinda new to clojure and following the braveclojure book. I reimplemented assoc-in and update-in in the exercises. Do these look idiomatic enough? http://sprunge.us/RGYN
12:33	justin_smith	pigoz: looks OK, though using update is sneaky :)
12:34	pigoz	you think it makes the exercise too easy?
12:38	justin_smith	pigoz: no, it's just funny because historically update-in was implemented first, and only later we got update
12:38	justin_smith	pigoz: of course using assoc instead of update would be simple
12:50	justin_smith	,(let [days-of-christmas (range 12 0 -1) total-presents (reduce #(+ % (apply + %2)) 0 (take-while seq (iterate rest days-of-christmas)))] total-presents)
12:50	clojurebot	364
14:10	troydm	I have some deftype, is it possible for it to implement CharSequence Java interface?
14:11	justin_smith	,(deftype Dum [] CharSequence (charAt [_ _] \d))
14:11	clojurebot	sandbox.Dum
14:11	justin_smith	,(.charAt (Dum.) 88)
14:11	clojurebot	\d
14:12	justin_smith	troydm: I guess if I was feeling less lazy I could have implemented the other three methods on the interface too
14:12	troydm	justin_smith: ic, that's what I was asking
14:12	troydm	justin_smith: thx
14:17	troydm	justin_smith: say I have (deftype A [a b c]) how do I access fields of that deftype outside of deftype method declaration?
14:18	justin_smith	,(deftype T [a])
14:18	clojurebot	sandbox.T
14:18	justin_smith	,(.a (T. 0))
14:18	clojurebot	0
14:19	troydm	oh, with a dot just like java methods
14:19	troydm	justin_smith: ic, thx
14:19	justin_smith	troydm: in fact, it is a method
14:22	sohail	does sente detect client disconnects on the server? Say the user quits the browser without clicking "quit" or whatever. I'm sure it must, but I don't see it.
14:24	troydm	justin_smith: can you explain what is (charAt [_ _] \d) <- the [_ _] part? it has two arguments
14:24	justin_smith	every method takes the object as the first argument
14:24	j-pb	troydm: there is no implicit this as in java
14:25	troydm	justin_smith: ohh
14:25	troydm	justin_smith: ic, ic
14:32	amalloy	except in proxy, har har
14:34	troydm	strange I'm trying to access field of deftype using .fieldName and it says no matching field found
14:35	justin_smith	troydm: are you sure it's an instance of the same deftype? changing the deftype definition doesn't change old objects to the new type
14:35	troydm	justin_smith: yeah, also field is volatile
14:36	troydm	^:volatile-mutable
14:36	troydm	also that deftype extends a Protocol
14:38	justin_smith	troydm: it's not mentioned in the docs but it makes sense - no accessor is generated if the field is not immutable
14:38	justin_smith	you are free to make an interface or protocol with a getA method
14:41	troydm	justin_smith: ah, ic, thx
14:43	justin_smith	troydm: so when do you use volatile fields? I'm scared of them because the vm is forced to synchronize every update with every thread
14:43	justin_smith	which feels like a heavy thing to be doing
14:44	troydm	justin_smith: err, well I didn't needed it to be volatile, just mutable only, so I had no idea actually how to make it only mutable
14:45	justin_smith	troydm: check out the docs for deftype " They are for experts only - if the semantics and implications of :volatile-mutable or :unsynchronized-mutable are not immediately apparent to you, you should not be using them."
14:45	justin_smith	troydm: the difference is that an unsynchronized-mutable can change without guaranteeing that the change is immediately visible in all threads
14:46	justin_smith	so on the one side you have to ensure that you aren't mutating from multiple threads, on the other every time you make a change you are slowing down every thread in the vm
14:46	troydm	justin_smith: well the thing I'm building won't be used in multiple threads simultaneously
14:47	justin_smith	then you could safely use an unsynchronized-mutable, and that will perform better, but the folks who wrote the doc string for deftype think you are in over your head
14:48	justin_smith	troydm: Java Concurrency in Practice is a good resource if you want to know how this stuff actually works. And it's scary. Immutability and queues become much more attractive after reading that book.
14:50	troydm	justin_smith: I've read it, and I know, thx for a hint
14:51	troydm	also when you write #"abc" does Clojure compile the regexp pattern or you need to explicitly compile it?
14:51	justin_smith	#"abc" returns a compiled regex
14:52	justin_smith	there is also re-compile if you want to do it by hand, or from a string generated at runtime
14:53	troydm	justin_smith: thx, ic
15:02	rhg135	re-pattern it's called
15:19	Bronsa	justin_smith: FYI deftype doesn't create getter methods, with (deftype A [foo]) (.foo (A. 1)) is the same as (.-foo (A. 1)) which is just a getfield call
15:19	Bronsa	with mutable fields those fields are private, that's why you can't access them
15:30	justin_smith	Bronsa: yeah, I knew it was a direct access and not a getter - I was suggesting with something mutable he would probably want a getter
15:31	justin_smith	Bronsa: but the private thing clarifies that, thanks
16:29	zacts	is Clojure from the Ground Up still good?
16:29	zacts	or what are the recommended resources for a complete Clojure newbie?
16:29	zacts	my main initial goal is to do Overtone music synth with Clojure
16:29	MJB47	i quite liked "the joy of clojure"
16:29	zacts	cool
16:29	zacts	MJB47: is this good for a complete newbie?
16:30	MJB47	yup, it assumed you know nothing about lisp
16:30	zacts	oh nice
16:30	zacts	perhaps I'll start there
16:30	pigoz	zacts: I am going through http://www.braveclojure.com/ but have used used lisp/clojure a bit before
16:31	zacts	pigoz: and you like it
16:31	pigoz	yes, the writing style is very fun and informal
16:31	pigoz	good for my attention span :)
16:32	zacts	ok
16:32	zacts	cool
16:32	zacts	thanks!
16:34	zacts	perhaps I'll start with brave clojure to get a feel for the flavor of clojure, and then I'll progress to the Joy of Clojure
16:34	justin_smith	4clojure.com is good for exercises
16:34	zacts	oh cool
16:38	pigoz	justin_smith: oh looks a like a great resource, thanks!
16:39	Seylerius	This is fun: the generated documentation for play-clj has some broken CSS causing the text to fail to render in Firefox, Chromium and Conkeror.
16:41	justin_smith	oops!
16:41	justin_smith	should be an easy pr, right?
16:45	Seylerius	Yep. Just need to figure out what they're using for docs and what broke it.
17:20	sohail	Do you have to do anything special to compile cljc besides add it to :source-paths?
17:20	justin_smith	no
17:20	justin_smith	the clojure and cljs compilers use it like they would any other file
17:21	sohail	I thought so, thanks.
17:26	TEttinger	cfleming: thanks for making open source development with cursive still possible on a nonexistent budget!
17:26	TEttinger	this is the best rosh hashanah ever
17:48	Seylerius	justin_smith: Turned out to be a failure of font failover.
17:56	justin_smith	Seylerius: so it just gives you nothing, instead of a default font?
19:38	BRODUS	say i wanted to model digital logic using core async, would a 'mult' be the right thing to use for a clock signal
19:38	stain	BRODUS: hmmm...
19:39	stain	but you would need to make sure the clocks synced up in the other end?
19:39	stain	send (tick,signal) in the channel?
19:40	stain	otherwise the complexity of your modelling function would falsely add delays
19:43	stain	but yes, I think a mult would work.. but you would either have to collect all the final channels before you tick the clock signal again (e.g. what you feed into the mult) or do as I say.. which would make your simulation asynchronous (you would probably still want to wait up if the delay is too big)
19:45	stain	sorry, this is late.. the blocking from the synchronous nature of mult might be enough for your purposes
19:45	stain	as you wouldn't be able to do the next tick before it's all gone through
19:45	BRODUS	its ok, thats what i was thinking
19:46	stain	I'm just thinking that in a digital logic circuit you would do a lot of gates meeting up again, and then you don't want any one of those to do a off-by-one for whatever reason
19:46	stain	e.g. an exception
19:47	stain	so I would want to basically do a dot product when you meet up so that you match on the clock tick (I guess any delay in the digital logic circuit would be part of the modelling)
19:47	BRODUS	well i dont think it would work if you had a clocked gate that depended on other clocked gates
19:48	stain	right, it could deadlock very easily, you can only do it with a single system clock (real time clock)
19:48	stain	and then base any frequency generators etc. of that one
19:49	BRODUS	i dont follow what you mean with the dot product
19:49	stain	oh.. if you pass (n,signal) then you need to match on n (e.g. the simulated system time tick)
19:50	stain	so you don't accidentally get offset
19:50	stain	or you would have to set your exception handler to kill the system clock
19:50	stain	have you used Keppler? It has a good tick simulation thingie
19:52	BRODUS	i will check it out
19:53	stain	https://kepler-project.org/
19:53	stain	it's a bit old and awkward
19:53	stain	but hey.. they did a Christmas release!
19:55	BRODUS	cool
20:22	tolstoy	Oy. Make a little screencast using QuickTime, can't edit and export it with ANYTHING that keeps the same fidelity.
20:33	tolstoy	1080p export -> blurry. ProRes -> 5 gigs.
20:34	ridcully_	are you sure, this is the right channel for this?
20:35	tolstoy	Of course it's not.
20:38	tolstoy	I _was_ trying to screencast a feature in a CLJS app ... ;), but hey, maybe #MacOSX might actually help.
22:32	kenrestivo	i vaguely remember there being a way to use compojure destructuring and still get the req too
22:32	kenrestivo	i.e. i've got (compojure/GET "/sched/:offset" [offset :<< coerce/as-int] ...) but i want the req too
22:34	justin_smith	kenrestivo: it's been a while, but doesn't compojure use something close to normal destructuring? can't you put an :as in there?
22:44	kenrestivo	yep, that does it, thanks
22:56	kenrestivo	jeez, i wrote a library a few years ago, completely forgot the name of it. had to look it up on github to find out.
23:36	kenrestivo	i wonder now if this already exists somewhere else: https://www.refheap.com/113147