#clojure – 2015-12-30

2015-12-30

00:15	mindbender1	Is boot operations slower than lein operations?
00:19	TEttinger	mindbender1: it's a good question.
00:19	TEttinger	~faster
00:19	clojurebot	faster is https://github.com/technomancy/leiningen/wiki/Faster
00:19	TEttinger	those are some suggestions for lein, they may be some for boot and some may apply to both (I think drip works for either)
00:22	mindbender1	TEttinger: I just wanted to be sure this was not happening only on my system.
00:23	TEttinger	are you using Boot and it's noticeably slower?
00:30	mindbender1	TEttinger: I have not really taken it for a proper test drive just the time it takes to do `boot -h` and `boot repl` got me concerned.
00:31	TEttinger	mm. lein repl takes a fair bit of time too for me
00:32	mindbender1	I guess I should play with it a bit more. And they better have good documentation for speed optimizations such as the one you pointed to.
00:33	mindbender1	One of the reasons I like lein is the author's will to make lein bendable to the user's will.
00:53	nys-	what does the .nrepl-port file do?
01:01	ridcully	nys-: it contains the port number of the nrepl
01:03	ridcully	e.g. tools/editors can pick it up. the port usually is random
04:00	favetelinguis	im building a webserver and am now looking for a way to spawn worker processes using core.async, both go blocks and threads will be used, the problem i have is how to manage starting and stopping of the processes at runtime, any known framworks that deals with this?
07:25	nicola	hi - i'm building something with lein uberjar, and i'm deciding where to put the resulting jar file in the unix filesystem (I'm making a debian package). Is there a conventional directory for these?
07:26	nicola	there will be a shell script that invokes 'java -cp ... args...' and it will go in /usr/local/bin, but i'm not sure where the jar itself should go
07:46	pvinis	hello. i have a list like (def a '(1 2 3 4)), and a fn that takes 4 args. how can i call that with my list?
07:47	pvinis	if i do (myfn a) then its just one arg
07:47	pvinis	can i explode it somehow?
07:50	luma	(apply myfn a)
07:54	pvinis	aha..
07:55	pvinis	cool. thanks
08:51	favetelinguis	what is the idomatic way to spawn and kill core-async go blocks at runtime? for example i need an go block to what makes rest request every 5sec push this out on a websocket, i need to be able to kill this go block when im done with it but since i want it to be controlled by time i cant use the pattern och blocking on the incomming channel
10:15	justin_smith	favetelinguis seems to have left, but they can block on the incoming channel and a timeout at the same time, by using alts!
10:18	TimMc	clojurebot: mutation is exciting!
10:18	clojurebot	c'est bon!
10:22	g0w	hi everyone.. i'm having some trouble understanding this syntax. How do I pass-in a different value of tempo?
10:22	g0w	https://www.irccloud.com/pastebin/3fktOx7x/tempo.clj
10:23	g0w	Can't quite the understand the destructuring that's going on in the function argument
10:23	clojurebot	Huh?
10:23	justin_smith	g0w: (test-args [] :tempo 80)
10:23	justin_smith	and we don't really use the & {} thing much any more
10:23	g0w	hello again @justin_smith
10:23	g0w	ah okay! thanks a lot!
10:24	g0w	what do we generally use in these cases?
10:24	justin_smith	g0w: just a hash map with keys and values
10:24	TimMc	Just drop the & and have a map arg there :-)
10:24	justin_smith	(like what you tried to use)
10:24	justin_smith	yeah
10:24	g0w	got it! thanks!
10:24	TimMc	You can add another arity to default the map to empty or nil.
10:25	g0w	@TimMc yup.. that would be my preference too.. i found this code in a book
10:26	g0w	so I had one meta question with immutability in clojure..
10:27	g0w	does the immutability thing hold true only for clojure datatypes?
10:27	g0w	for example, I was using a BitSet yesterday, and calling (.set bitset) didn't return a new bitset
10:27	justin_smith	the clojure datatypes, strings, and primitives are all effectively immutable
10:27	justin_smith	everything else is mostly mutable, it's the same objects java uses
10:27	engblom	I am new to concurrent programming with Clojure and I want to check up if I understand things right. First, can I from two different threads define the same named promise?
10:28	engblom	And if I am able to define the same named promise in both, and I deliver from a third thread, will only one of the other threads quit blocking if both do deref?
10:28	justin_smith	engblom: yes, but it might not do what you want. Where is the name being assigned?
10:28	justin_smith	do you mean def?
10:29	g0w	so the issues with using java objects in writing concurrent code still exist? ie. i would need to manually synchronize access to a bitset object ?
10:29	justin_smith	g0w: pretty much, yeah. And you shouldn't put mutable objects inside atoms or refs either
10:30	g0w	ok.. got it.. what's the accepted best practice in these cases? rely as less as you can on java objects?
10:30	yenda	is there a way to check for more recent dependencies with boot ?
10:30	justin_smith	engblom: to be super pedantic, promises never have names, but using let or def you can bind one to a name, and either will let you bind two things to the same name, and simply render the first one inaccessible by name
10:32	engblom	justin_smith: Assume I have two threads, both doing binding my-promise either through let or def (for example (def my-promis (promise)) ) Then a third thread is started and it does (deliver my-promise "whatever"). Both original threads are doing @my-promise, will one of them continue to block
10:32	engblom	?
10:34	TimMc	g0w: Clojure doesn't change the way Java and the JVM work, it just provides alternatives and wrappers.
10:34	justin_smith	engblom: well, you can't have more than one thread binding values in a single let block, so we have to assume it is defs. and yes, the one waiting on the first promise will wait forever, because nobody else has a handle on the old promise, and nobody will deliver to it.
10:34	justin_smith	engblom: this is just one reason def at runtime is usually wrong
10:35	TimMc	g0w: If you need to modify BitSets, your functions will need to be defensive in the same way that Java methods need to be defensive -- cloning.
10:35	g0w	cloning? can you elaborate a bit more?
10:35	engblom	justin_smith: To be more specific, I am looking at this library: https://github.com/juxt/dirwatch
10:36	TimMc	g0w: If I hand you a mutable object, you might want to create a copy so that I can't accidentally modify your instance.
10:36	g0w	but woulnd't a deep clone of every object be expensive with no structural sharing in place?
10:37	TimMc	It can be, yes.
10:37	justin_smith	but you shouldn't need deep cloning, because you don't need the mutable collection types
10:37	engblom	justin_smith: I wish to use it in this way: Wait blocking until a certain file has changed. So I planned to use promises, and have the function 'watch-dir' will run to deliver
10:37	g0w	justin_smith: BitSet is a mutable collection type, right?
10:38	engblom	But then I begun to wonder if this is thread-safe. What will happen if several processes does the very same on the same file?
10:38	justin_smith	kind of - it's not really a container though, it can only hold bits (a real container can contain any Object type). you don't "deep copy" a bitset, you just copy it
10:39	g0w	@justin_smith: ah yes, I get what you mean.
10:39	justin_smith	engblom: if you set up the promise to be delivered to, the process waiting on the promise, and the watcher to deliver to the promise, all in one local scope, there's no chance of "clobbering". The clobbering would happen if you were using a def and there was a race condition in your def usage.
11:05	jjttjj	I have a connection object from a java library i'm working with. It relies on some external state, for instance a new client-id is needed for each connection. requests can be made from the connection, and each request must have a unique, auto-incrementing ID, and i’m queueing all responses to the requests in a core.async chan. do i just shove all these things in a map when I create a connection and pass it around everywhere?
11:12	justin_smith	jjttjj: there are many ways to handle this. You could use an atom with a map, you could create a go block that lexically closes over each ID and then broadcast via core.async...
11:24	m1dnight_	A bit off topic, but are there some more general programming-related channels I could check out on freenode (or others)?
11:30	sdegutis	m1dnight_: ##programming
11:30	sdegutis	m1dnight_: ##webdev
11:30	m1dnight_	Oh, that is rather obvious :> thanks
11:30	m1dnight_	Joined them
11:30	sdegutis	:)
12:04	favetelinguis	i want to conj to a IPersistentCollection, is this possible or how can to clone the IPersistentCollection vector and then use the new to conj what i want?
12:35	TimMc	,(clojure.string/escape "foo" {\o \e})
12:35	clojurebot	"fee"
12:36	TimMc	favetelinguis: IPersistentCollection is pretty vague. Do you know anything else about the value?
12:51	sfz-	,(clojure.string/escape "foo.com?q=bar baz qux" {' ' '+'})
12:51	clojurebot	#<RuntimeException java.lang.RuntimeException: Map literal must contain an even number of forms>
12:51	sfz-	hm
12:51	MJB47	use " instead of '
12:51	sfz-	,(clojure.string/escape "foo.com?q=bar baz qux" {" " "+"})
12:51	clojurebot	"foo.com?q=bar baz qux"
12:52	sfz-	nope, how would you replace a space?
12:52	MJB47	try string/replace
12:53	TimMc	,(clojure.string/escape "f " {space \o})
12:53	clojurebot	#error {\n :cause "Unable to resolve symbol: space in this context"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.RuntimeException: Unable to resolve symbol: space in this context, compiling:(NO_SOURCE_PATH:0:0)"\n :at [clojure.lang.Compiler analyze "Compiler.java" 6704]}\n {:type java.lang.RuntimeException\n :message "Unable to resolve symbol: space in this...
12:53	TimMc	urgh
12:53	TimMc	,(clojure.string/escape "f " {\space \o})
12:53	clojurebot	"foo"
12:53	TimMc	sfz-: ^ But really you wouldn't, you'd use a URL library.
12:53	sfz-	,(clojure.string/escape "foo.com?q=bar baz qux" {\space \+})
12:53	clojurebot	"foo.com?q=bar+baz+qux"
12:53	justin_smith	favetelinguis: when you call conj on any object implementing IPersistentCollection you get a copy with your data added to the collection
12:54	sfz-	TimMc: right, was just curious, thanks!
12:54	sfz-	TimMc: I know ring lib has stuff for that, still a relative n00b to clj though so trying to pick up all the tricks I can
12:55	justin_smith	,(java.net.url/URLEncode "foo.com?q=bar baz qux" "UTF-8")
12:55	clojurebot	#error {\n :cause "java.net.url"\n :via\n [{:type java.lang.ClassNotFoundException\n :message "java.net.url"\n :at [java.net.URLClassLoader$1 run "URLClassLoader.java" 366]}]\n :trace\n [[java.net.URLClassLoader$1 run "URLClassLoader.java" 366]\n [java.net.URLClassLoader$1 run "URLClassLoader.java" 355]\n [java.security.AccessController doPrivileged "AccessController.java" -2]\n [java.net.U...
12:56	justin_smith	,(java.net.URLEncoder/encode "foo.com?q=bar baz qux" "UTF-8")
12:56	clojurebot	"foo.com%3Fq%3Dbar+baz+qux"
12:56	justin_smith	really you would only encode the part that goes after the ? of course
12:56	sfz-	right
12:56	sfz-	thanks again
12:56	TimMc	,(->> (range 256) (map char) (filter #(not= (count (pr-str %)) 2)))
12:56	justin_smith	,(str "foo.com?" (java.net.URLEncoder/encode "q=bar baz qux" "UTF-8")
12:56	clojurebot	#<RuntimeException java.lang.RuntimeException: EOF while reading>
12:56	clojurebot	(\backspace \tab \newline \formfeed \return ...)
12:57	justin_smith	,(str "foo.com?" (java.net.URLEncoder/encode "q=bar baz qux" "UTF-8"))
12:57	clojurebot	"foo.com?q%3Dbar+baz+qux"
12:57	TimMc	except URLEncoder is wrong :-(
12:57	justin_smith	TimMc: I still think I'm using it wrong...
12:57	TimMc	and this is where replace actually does come in
12:57	sfz-	,(ring.util.codec/url-encode "clojure url")
12:57	clojurebot	#error {\n :cause "ring.util.codec"\n :via\n [{:type java.lang.ClassNotFoundException\n :message "ring.util.codec"\n :at [java.net.URLClassLoader$1 run "URLClassLoader.java" 366]}]\n :trace\n [[java.net.URLClassLoader$1 run "URLClassLoader.java" 366]\n [java.net.URLClassLoader$1 run "URLClassLoader.java" 355]\n [java.security.AccessController doPrivileged "AccessController.java" -2]\n [java...
12:57	sfz-	aw, no clojars eh?
12:57	justin_smith	sfz-: clojurebot won't have any ring stuff
12:57	TimMc	justin_smith: https://github.com/timmc/johnny/blob/master/src/main/java/org/timmc/johnny/Codecs.java#L28
12:58	justin_smith	sfz-: it might use clojars, but that's not how you add something ot the classpath
12:58	justin_smith	TimMc: ahh
12:58	TimMc	wait, that's decoding... but you just do it in reverse
13:47	jjttjj	how should i clojureize the name of the java class EClientSocket... "e-client-socket"? "eclientsocket"? first seems more typical but looks weird here is the second one dumb to do?
13:48	jjttjj	maybe i'll just do ecs/ECS?
13:49	justin_smith	why are you clojureizing a class name?
13:49	jjttjj	i need to stick the connection object in a map, trying to figure out what to name the key
13:51	justin_smith	I would usually use a key like :socket - depending on context etc. of course
13:51	jjttjj	justin_smith: cool thanks! getting hung up on dumb things today
14:02	TimMc	:☃-socket
14:03	justin_smith	TimMc: well, it is a Snowman, so as an initialism :☃ ocket should work
14:07	TimMc	nice, even more concise
14:07	justin_smith	it even has a compatible outline
15:08	TimMc	Incanter doesn't appear to have fourier transforms... what am I missing?
15:36	justin_smith	TimMc: clearly they expect every user to hand-roll their own fft
15:36	creese	I've been reading about om.next. I'm wondering what if anything has been done on the back-end portion. Has anyone build a ring app that takes om.next queries and return responses using a datastore other than Datomic?
15:37	Kajtek	Hi guys, so I've run into a problem when using map destructuring and lazy sequences.
15:37	Kajtek	Basically, whenever I pass a lazy seq with odd number of elements to a function that uses destructuring I get an exception.
15:37	Kajtek	Even-numbered sequences work as expected.
15:38	Kajtek	Here's a minimal reproduction: ((fn [{:keys [k]}] k) (lazy-seq [{:k :a}]))
15:38	Kajtek	Is it a known bug? I don't really follow Clojure development.
15:38	Kajtek	Also, this happens on Clojure 1.7.0.
15:38	MJB47	{:keys...} only works correctly if the input is a map
15:38	justin_smith	Kajtek: that argument is incorrect
15:38	MJB47	you have a sequence of maps
15:39	justin_smith	if you replaced [{:keys [k]}] with [[{:keys [k]}]] in the function definition it would work
15:39	justin_smith	(but other calls would likely break)
15:40	Kajtek	Then it working for even-numbered seqs is kind of misleading.
15:40	justin_smith	Kajtek: yes, it works accidentally, and is unlikely to give a correct result
15:40	justin_smith	Kajtek: there are many things in clojure that work accidentally
15:41	justin_smith	,(:or :a :b) ; a classic mistake, which might even pass your tests sometimes
15:41	clojurebot	:b
15:42	Kajtek	I guess warts happen.
15:42	Kajtek	Thanks for the help. I suppose I'll get rid of destructuring and check if the argument passed is a map beforehand.
15:43	ystael	justin_smith: chokes on popcorn that's a trap that never occurred to me
15:43	justin_smith	ystael: I've seen it!
15:43	justin_smith	,(:or false :a) ; the version that looks like it works
15:44	clojurebot	:a
15:44	ystael	i don't think i knew that keyword-as-map-extractor could take a second arg
15:44	justin_smith	ystael: see also (:require '[it doesn't matter what you put here]) - returns nil, as you expect
15:44	justin_smith	and of course, does nothing at all
15:45	ystael	this sounds like an argument for tutti frutti syntax coloring
15:46	justin_smith	heh - or a stricter programming language :P
15:46	ystael	Well, yes, but this is #clojure :)
15:46	justin_smith	ystael: syntax highlighting wouldn't work with the :require mistake - you expect it to be a keyword, you just don't realize it only works like that inside the ns macro...
15:47	ystael	Fortunately I typically err in the opposite direction instead, typing (require '[...) inside the ns macro
15:48	justin_smith	it's an easy typo/thinko to make, because the syntaxes are so similar, and they do the same thing, they just happen to be incompatible and one of them tends to be a silent noop
15:48	ystael	ah well, I use clojure because it's a good set of practical compromises, not because I think it's perfect :)
15:48	justin_smith	thinko is of course short for thinkographical error
16:00	jiamo	I find hard to transalte this algorthm into clojure
16:00	jiamo	n=”the evil big number” if n mod 2=0 then lastFactor=2 n=n div 2 while n mod 2=0 n=n div 2 else lastFactor=1 factor=3 maxFactor= n while n>1 and factor<=maxFactor if n mod factor=0 then n=n div factor lastFactor=factor while n mod factor=0 n=n div factor maxFactor= n factor=factor+2 if n=1 then output lastFactor else output n
16:01	jiamo	It is a Procedural paradigm
16:02	justin_smith	jiamo: the trivial transormation is to turn the while into a loop, and make every value mutated inside the while into a loop binding
16:02	justin_smith	that doesn't always give the best result of course, but its the version that is easiest to translate
16:03	justin_smith	nested while might require a let binding to bind the loop variables coming out from the inner loop
16:04	justin_smith	also, if you have multiple mutations inside one cycle, you can use shadowing in a let block, or explicitly transform it into multiple vars, each chaining from the previous one's value
16:13	justin_smith	oh, how sad, I started to play with how one would translate that, then realized the block syntax in that pseudo code is totally ambiguous and jiamo isn't here to ask for clarification
16:16	sohail	is there a way to dispatch on the values in a vector without unpacking it just for dispatch? Specifically, I have a vector that looks like this: [:keyword {..}]
16:17	justin_smith	sohail: what do you mean by "without unpacking it" ?
16:18	sohail	justin_smith: I mean without doing something like (my-multi (first data) (second data))
16:18	justin_smith	(defmulti my-multi first)
16:18	sohail	oh!
16:19	sohail	I think I need to read this stuff more carefully
16:19	justin_smith	or maybe (defmulti my-multi (comp type first)) if you still want to dispatch by type...
16:19	justin_smith	and that needs adjusting if your method takes multiple args too, of course
16:20	justin_smith	sohail: there are a lot of examples of defmulti on grimoir - it can do a lot!
16:20	sohail	what is grimoir?
16:20	justin_smith	http://conj.io/store/v1/org.clojure/clojure/1.7.0/clj/clojure.core/defmulti/
16:20	justin_smith	conj.io is grimoir
16:21	justin_smith	incidentally, I fixed and/or wrote most of the defmulti examples myself
16:22	sohail	awesome, thanks justin_smith
16:24	amalloy	justin_smith has accidentally betrayed his alter-ego, MultiMethodMan
16:25	justin_smith	what's that? commisioner Gordon has lit the dispatch signal - wait a moment while I look up the method that signal dispatches to
16:28	amalloy	oh no! the joker has replaced your dispatch function with (#(% %) #(% %))! now you'll never get to the crime scene in time!
16:28	justin_smith	haha
16:29	justin_smith	holy combinators batman!
16:34	TimMc	I want to bucket a list of monotonically increasing numbers by multiples of 1000, e.g. [1 35 456 2005 3045 3987] => [[1 35 456] [] [2005] [3045 3987]]
16:34	TimMc	I think my best bet is a loop and split-with, but is there something even simpler?
16:35	justin_smith	,(group-by #(count (str (/ % 1000))) [1 35 456 2005 3045 3987]
16:35	justin_smith	oops
16:35	clojurebot	#<RuntimeException java.lang.RuntimeException: EOF while reading>
16:35	justin_smith	,(group-by #(count (str (/ % 1000))) [1 35 456 2005 3045 3987])
16:35	clojurebot	{6 [1 456], 5 [35], 7 [2005 3045], 9 [3987]}
16:36	justin_smith	oh, that wasn't a truncating divide, d'oh
16:37	TimMc	The key is that I also want empty buckets.
16:37	justin_smith	,(group-by #(int (/ % 1000)) [1 35 456 2005 3045 3987])
16:37	clojurebot	{0 [1 35 456], 2 [2005], 3 [3045 3987]}
16:37	justin_smith	ahh
16:38	justin_smith	TimMc: maybe a trick with (comp max keys) and range and (fnil (m %) [])
16:38	TimMc	hrm
16:38	ystael	or you could just write the reduce by hand
16:38	luma	,(mod 2005 1000)
16:39	clojurebot	5
16:39	luma	ah, not modulo
16:39	ystael	(you have reduce, why do you need anything else? :))
16:39	TimMc	I think loop is better here since I need to bind 2-3 values on each iteration.
16:39	luma	,(quot 2005 1000)
16:39	clojurebot	2
16:39	luma	this one
16:40	justin_smith	luma: yeah, better to use quot than (comp int /)
16:42	TimMc	Here's my solution: https://gist.github.com/timmc/35c969e97ac1c5e7f72f
16:43	justin_smith	(let [in [1 35 456 2005 3045 3987] by-count (group-by #(quot % 1000) in)] (map #(get by-count % []) (range (inc (apply max (keys by-count))))))
16:43	justin_smith	,(let [in [1 35 456 2005 3045 3987] by-count (group-by #(quot % 1000) in)] (map #(get by-count % []) (range (inc (apply max (keys by-count))))))
16:43	clojurebot	([1 35 456] [] [2005] [3045 3987])
16:44	TimMc	"now make it lazy"
16:44	justin_smith	:)
16:45	TimMc	I've made a maximally lazy coll-of-colls splitter like this before and it was annoying to write: https://github.com/timmc/rand/blob/master/src/rand/core.clj#L26
16:46	TimMc	The approach was to lazily inject sentinels at the boundaries, then lazily group on the sentinels.
16:58	justin_smith	,(let [ord #(quot % 1000)] (apply mapcat (fn [prev sub] (concat (repeat (dec (- (ord (first sub)) (ord (first prev)))) []) [sub])) ((juxt identity rest) (cons [0] (partition-by ord [1 35 456 2005 3045 3987]) )))) ; bizarre, but works and is lazy
16:58	clojurebot	((1 35 456) [] (2005) (3045 3987))
16:59	justin_smith	there is probably a way to make that less loony
17:02	justin_smith	also that [0] should probably be a -1 and the behavior around various orders of magnitude as starting values probably needs fixing
17:05	tolstoy	clojars still out, eh?
17:06	justin_smith	oh wow, what happened?
17:06	tolstoy	No idea. My "lein ancient" was having issues. Checked: https://linode.statuspage.io, which clojars mentioned on their twitter account 3 days ago.
17:07	tolstoy	Ah, it's back in the browser, now.
17:07	justin_smith	tolstoy: https://twitter.com/clojars
17:07	justin_smith	oh, d'oh, while I am looking that up you mention their twitter, heh
17:07	tolstoy	Yeah, that was Dec 27.
17:08	justin_smith	do you know which location they are using?
17:08	tolstoy	Okay, it's back.
17:08	tolstoy	No idea.
17:11	TimMc	linode is being DOS'd
17:11	TimMc	Has been for a couple days, I think?
17:12	tolstoy	Fastmail's been having a problem as well.
17:12	tolstoy	AIs getting a little feisty?
17:19	TimMc	Someone's probably trying to extort them.
17:53	justin_smith	repeating my core.async / cljs question here because #clojurescript is looking a bit underattended right now
17:53	justin_smith	OK, I have an issue that comes up because <!! is missing in cljs
17:53	justin_smith	in my cljs startup, I need to delay the rest of the app coming up until I get a specific message on a core.async channel
17:54	justin_smith	in other words I need to block until I get a message - but can't use <!!
17:54	justin_smith	is there a sane / normal way to do this? - I understand realistically that the code which sends the message would be blocked if I used <!!, but I also don't want to suck all my init code up into a go block just so I can synchronize on a channel at one place
17:54	tolstoy	Are you using one of the reacty things?
17:54	justin_smith	yes, but none of the reacty crap is running yet when this happens
17:55	tolstoy	Oh. I was going to suggest just run as normal, but set a prop in the state such that nothing gets rendered.
17:55	justin_smith	this is during initial page load, handshaking a websocket with the server, and then I need a specific message from the server before the rest of the code in the app can safely run
17:55	tolstoy	When the appropriate message comes in, reset that, and the GUI will pop-up.
17:55	justin_smith	tolstoy: yeah, this is about more than props
17:55	justin_smith	right
17:56	tolstoy	(swap! state assoc :view :loading)
17:56	tolstoy	I do that, anyway.
17:56	justin_smith	tolstoy: I'm actually using stuart sierra's component lib, and this is a component init, and really I don't want to return from the init of this component until the confirmation message (and the data it sends) is present
17:56	tolstoy	If (:user state) is nil, render a loading component. Eventually, data comes in and it works.
17:57	justin_smith	other components do things (before react renders) that will break badly if this data is not present
17:57	tolstoy	Oy.
17:57	justin_smith	and I can't just put the data in the cljs file
17:58	tolstoy	That's a bit of a monkey-wrench.
17:58	bja	justin_smith: could you use take! and write a function that delivers to a promise then deref that?
17:58	justin_smith	bja: no promises in cljs!
17:58	justin_smith	I thought of that one too
17:58	bja	could you use $.deferred or something likethat?
17:58	justin_smith	hmm... we aren't using $ at all, but maybe there's an alternative I could use
17:59	bja	isn't there a pure-cljs promise library
17:59	justin_smith	bja: maybe, I didn't check for that
17:59	bja	https://github.com/funcool/promesa
17:59	justin_smith	it would be just the thing I guess as long as it played nicely with async stuff that needs to happen
17:59	tolstoy	https://github.com/jamesmacaulay/cljs-promises
18:00	justin_smith	and when I say that, I start to think maybe I do need to suck my whole component system into core.async... oh no
18:00	tolstoy	Maybe have a whole bootstrap system, then invoke component stuff once it's complete?
18:01	justin_smith	maybe I could pull this component out of stuartsierria/component and start it first
18:02	justin_smith	usint take with a "start all the other components" as the callback?
18:02	justin_smith	clearly we need "components, but async"
18:02	bja	does component work in cljs now?
18:03	tolstoy	(go (let [data (<! (bootstrap))] (start-system data)))
18:03	justin_smith	yeah - I did my own cljc port ages ago, and eventually I will switch to the official cljc port which came out more recently
18:03	justin_smith	tolstoy: exactly
18:03	justin_smith	tolstoy: that's probably what I need to do, thanks
18:04	justin_smith	the sad thing is that I had been using a shared component for the websockets - same code for frontend and backend, this would mean splitting them
18:05	justin_smith	but it's probably for the best, there was a high density of conditionals already
18:06	tolstoy	I've never have luck with shared code until the end of a project. That's when I figure out the abstractions I actually needed.
18:07	bja	as an aside, people who start nrepls outside of lein repl and use components, do you have an nrepl component? Do you start it outside the rest of your system?
18:09	tolstoy	Maybe take a config prop and add it to the SystemMap depending on that prop?
18:10	bja	maybe
18:11	justin_smith	yeah - I would make a component that is either optionally part of the system map, or optionally starts the nrepl
18:11	tolstoy	Yeah. Could just take a config and then when "start" is called, does (potentially) nothing.
18:11	tolstoy	I like that better.
18:11	justin_smith	if you have lots of things that conditionally start, then it can be cool to manipulate that in the system map rather than having lots of conditional short circuits in the components
18:12	bja	right now mine just conditionally starts
18:12	justin_smith	I even made a simple "resolver", which says "start my system, but without foo" and it removes foo, and anything that depends on foo, before starting the system
18:12	bja	or rather, it always tries to start, but we accept failure as an option, and we never actually stop it
18:13	justin_smith	it's all data!
18:13	bja	from when I was doing storm stuff I was making a lot of systems and so I represent logical systems as maps and then merge those together before creating the system map
18:14	bja	since different bolts needed different stuff
18:14	bja	so I ended up with a myriad of systems
18:14	bja	I also have a settings component
18:15	bja	that, out of the box, uses environ to resolve settings, reconciles those against a schema for the system, and if all that works, continues
18:15	justin_smith	cool
18:15	justin_smith	bja: it's pretty cool what you can do with something represented as data structures
18:15	bja	so that my settings are available in the map (to be depended on (and destructured, but that's a different story))
18:16	bja	so that components can want something like db-uri, but I can destructure/rename analytics-db-uri for that component
18:17	bja	yeah
18:17	bja	the basis of most of the "amazing wins" (to some of the people I work with) are just due to representing as much of my world as data as possible
18:18	bja	leads to some really cool wins like being able to use the same query language to define data permissions as well as store partial filters and execute real-time matches against incoming docs
18:20	justin_smith	this line of thought makes me think we could do some really amazing things if we made better data validation tools (prismatic/schema is great, but I think other tools could be useful too (even if I don't know what they look like yet))
18:21	tolstoy	Yeah, even just storing the config as EDN (or JSON, I guess) and using prismatic really makes QA think you're with it.
18:21	bja	yeah
18:22	bja	basically all of our apps have something like this: https://gist.github.com/emidln/005fa93f70744cc5fe5f
18:23	bja	it's very nice to be able to be able to know exactly where to look for config settings and what their expected format is
18:23	bja	also nice not having to validate that all over the app
18:23	justin_smith	very cool
18:26	tolstoy	Speaking of p/schema: vectors of variable types. Not [(s/enum t1 t2 t3)]?
18:30	justin_smith	(s/validate [s/Any] [:a 1]) works
18:30	justin_smith	depends what all needs to be in there?
18:30	justin_smith	Any may be broader than what you want of course
18:31	tolstoy	{:id uuid :type :a :data [...]} with three different "type" values. The data depends on the type.
18:31	tolstoy	I can make a schema for each one, but not sure how to put them in the envelope.
18:31	justin_smith	oh, so what is allowed in :data needs to be calculated based on the value for :type
18:32	tolstoy	Yeah. Kinda like {:id "asda" :type :num :data 23}.
18:32	justin_smith	once you have that piece of data, you can do (s/validate [(:type m)] (:data m))
18:32	justin_smith	wait, that's not in a vector!
18:33	justin_smith	you said it would be in a vector
18:33	tolstoy	Well, I'm trying to be abstract.
18:33	tolstoy	Imagine a collection schema with three possible shapes. Enum isn't working.
18:33	tolstoy	Perhaps "maybe".
18:33	justin_smith	tolstoy: sure - general idea, you can look up the schema (in a map you make for example) based on the :type tag
18:33	justin_smith	then validate the :data key
18:34	tolstoy	Ah, so a two part validation step.
18:34	justin_smith	right
18:34	justin_smith	this is a lisp after all!
18:34	justin_smith	tolstoy: this is of course more fiddly and less general than a regular schema
18:35	justin_smith	there may be a way to "hoist" this concept into a proper schema that validates if the :data and :type keys agree in the way we are describing
18:35	tolstoy	Yeah. Seems like they'd have a way to validate a heterogeneous collection of values.
18:35	tolstoy	Given that's allowable in Clojure. Perhaps it's just too ill-advised. ;)
18:36	tolstoy	Maybe "either" is it.
18:37	tolstoy	Deprecated. Hm. "conditional" I guess.
18:38	rhg135	pred is also an option
18:40	tolstoy	java.lang.IllegalArgumentException: No implementation of method: :spec of protocol: #'schema.core/Schema found for class: clojure.lang.Keyword
18:41	tolstoy	sigh
18:42	tolstoy	Can you validate exact keywords?
18:42	justin_smith	tolstoy: this is why I was suggesting looking up the schema in a hash map, based on the key under :data
18:42	justin_smith	oh, I misunderstood
18:43	tolstoy	I think there's a facility for that (s/contitional :a ThisSchema :b ThatSchema).
18:43	tolstoy	Assuming :a is invoked as a function in the value. No actual example of contitional.
18:44	rhg135	s/eq
18:45	rhg135	that validates equality
18:46	tolstoy	thanks!
18:46	tolstoy	Hm. The s/conditional is "cond" like, but how do you get a reference to the value?
18:48	rhg135	I think the first args of the pairs, like :a or :b in your example, are ifn
18:49	rhg135	predicates
18:49	tolstoy	I end up having to do (s/condition (= #(:type %) :text) TextSchema ..).
18:49	tolstoy	Now I get a "value does not match schema" and it prints 15 lines. ;)
18:55	tolstoy	Hah! Worked!
18:56	rhg135	yay
18:56	tolstoy	(s/conditional #(= (:type %) :foo) FooSchema #(= (:type %) :bar) BarSchema)
18:56	justin_smith	tolstoy: sweet
18:56	justin_smith	TIL
18:56	tolstoy	Sure is nice, in Cider, to just C-x, C-e stuff and have to shoot out the side of the function.
18:58	tolstoy	justin_smith: It was basically what you said, except inside the DSL.
18:58	rhg135	now just factor it out to a type? function that returns a predicate, and BAM!; declarative!
18:58	tolstoy	Yeah.
18:58	justin_smith	(inc rhg135)
18:59	rhg135	I'm glad they finally implemented this
19:02	tolstoy	It's almost like having algebraic types.
19:03	rhg135	if you squint hard, defschema looks like type
19:08	tolstoy	I kinda like the schema emphasis on data validation rather than type signatures. Feels like lateral thinking compared to most language concerns.
19:51	TimMc	justin_smith: Something went deeply wrong with that bucketing code I wrote. I know that it should only have about 4 items per bucket, but I graphed the results, and 2 of the buckets ended up with ~30000 items.
19:51	justin_smith	woah
19:51	TimMc	ohshi-
19:52	justin_smith	TimMc: well I did show you that lazy version (which might have an issue or two still, but not like that...)
19:52	TimMc	I know what went wrong! The data wasn't monotonically increasing, that's how I screwed up.
19:52	TimMc	hahahahaha
19:52	justin_smith	oh, that would do it!
19:53	TimMc	I wonder how long it takes to sort a million timestamps.
19:53	justin_smith	one million
19:55	TimMc	O(100000*log(1000000))
19:56	TimMc	justin_smith: I had tried to do a fourier transform on the event counts per second and got this: https://i.imgur.com/XODAZSp.png
19:57	justin_smith	pretty!
19:57	TimMc	yeah!
19:57	TimMc	(the graph oscillates between two curves, creating a solid appearance)
19:58	TimMc	But clearly screwed up, since I was expecting something mostly flat with a big spike and a couple side spikes.
19:58	justin_smith	at this moment I would like to say that stuartsierra's decision to make hash maps implement component by returning themselves when you call start was a very smart decision that makes this refactor very easy
19:59	tolstoy	Heh. That really screwed me up for a while, missing that fact.
20:00	tolstoy	How come component worked in the repl, but not when starting via a main method?
20:00	tolstoy	(I thought the SystemMap contained an atom or something.)
20:33	athan	Does clojure like monads?
21:25	tolstoy	athan: https://github.com/clojure/algo.monads ?
21:37	princeso	1) write 0. (zero dot) in your REPL. 2) put the cursor between them (0\|.) . 3) write a digit 4) ?? 5) profit.
21:38	justin_smith	princeso: what was that supposed to do?
21:38	g0w	https://usercontent.irccloud-cdn.com/file/LiQkSixv/Screen%20Shot%202015-12-30%20at%209.37.40%20PM.png
21:39	g0w	princeso: this is expected, right?
21:39	princeso	justin_smith There is some bug that prevents from writing digits. i dont know.
21:39	justin_smith	princeso: not in my repl
21:40	g0w	princeso: works for me too
21:40	justin_smith	princeso: what repl - maybe it's a bug in your editor or terminal?
21:42	g0w	anyone done with problem 8 with advent of code? I'm stuck on it since like forever :\|
21:43	princeso	it is the one provided by CCW i guess.
21:49	princeso	justin_smith im using this clojuresque:clojuresque-nrepl:1.0.0
21:50	justin_smith	princeso: CCW has been unsupported for a while, right?
21:52	princeso	g0w that was like ... you profited
21:53	g0w	:D
21:55	princeso	what repl are you using?
21:58	princeso	g0w what problem is that?
21:59	g0w	me? the standard one... lein repl - http://i.imgur.com/PVbYrDX.png
21:59	justin_smith	nice prompt string
22:00	princeso	good
22:00	tester	hey all
22:00	g0w	princeso: the problem about escaping strings - having a hard time figuring out how to escape the ", \ etc. http://adventofcode.com/day/8
22:00	g0w	thanks @justin_smith
22:01	justin_smith	g0w: oh, interesting - did you check out pr-str ?
22:02	justin_smith	,(pr-str "\"")
22:02	clojurebot	"\"\\\"\""
22:02	justin_smith	,(count (pr-str "\""))
22:02	clojurebot	4
22:02	g0w	,(count (pr-str "\x27"))
22:02	clojurebot	#<RuntimeException java.lang.RuntimeException: Unsupported escape character: \x>
22:02	g0w	how do i get the \x27 testcase to work?
22:02	justin_smith	yeah, we don't use the same escapes
22:02	justin_smith	you need an adaptor I guess...
22:03	justin_smith	,(count (pr-str "\\x27"))
22:03	clojurebot	7
22:03	justin_smith	they they don't expect "\\x27" to print as \x27
22:04	g0w	"\x27" is 6 characters of code
22:04	g0w	that's the part i'm struggling with
22:06	justin_smith	well, it's 6 characters in some language
22:06	justin_smith	illegal in ours
22:06	g0w	yup
22:07	g0w	but if we can't somehow make it match 6, we wouldn't be able to make the testcase pass right?
22:08	justin_smith	g0w: oh, you could compare count of str of the string to count of print-str of string
22:08	justin_smith	,(map count (juxt str print-str) "\\")
22:08	clojurebot	#<IllegalArgumentException java.lang.IllegalArgumentException: Don't know how to create ISeq from: clojure.core$juxt$fn__4498>
22:09	justin_smith	,(map count ((juxt str print-str) "\\"))
22:09	clojurebot	(1 1)
22:09	justin_smith	err
22:09	justin_smith	I know there is a way to make this work!
22:10	justin_smith	,(map count ((juxt str pr-str) "\"\\x27\""))
22:10	clojurebot	(6 11)
22:13	g0w	the output we're looking for is (6 1) right/
22:13	g0w	?
22:14	justin_smith	yeah, so that's not helping at all
22:14	justin_smith	you would need your own rule to turn \xNN into a single result
22:15	justin_smith	,\u0027
22:15	clojurebot	\'
22:15	justin_smith	turn every \x into a \u00 ?
22:15	amalloy	it's really not hard to implement that by hand. trying to use pr-str and such is cute, but not really worth the hassle
22:16	justin_smith	yeah, probably not, you're right
22:16	amalloy	like my solution in haskell was trivially short, and very simple/clear: https://github.com/amalloy/advent-of-code/blob/master/day8/src.hs
22:17	g0w	,(- (count "\"\u0027\"") 2)
22:17	clojurebot	1
22:18	g0w	@amalloy: is this for part 1 or part 2?
22:18	amalloy	both. the first function is part1, the second part2
22:19	g0w	is that pattern matching?
22:19	amalloy	yeah
22:19	g0w	sorry.. i've never read haskell code before
22:20	amalloy	you could do something similar in clojure with a bunch of cond clauses
22:20	justin_smith	or the silly way, with multimethods
22:21	amalloy	(cond (empty? s) 2, (.startsWith s "\\x") (+ 3 (overhead (drop 4 xs))) ...)
22:21	amalloy	though i guess you'd need to use subs instead of drop, if you want to use string operations
22:22	amalloy	multimethod man to the rescue?
22:22	g0w	amalloy: the trick is to replace "\x" into a \u00?
22:22	amalloy	well that was justin_smith's proposal
22:23	justin_smith	I think amalloy has the better plan here
22:23	amalloy	i'm just saying to write a recursive function on a string, and if you find it starts with \x then remove 4 characters from the string and add 3 to the recursive call
22:23	g0w	amalloy: got it.. let me give this a shot
22:26	amalloy	justin_smith: i did try implementing it with haskell's versions of pr-str and read-string though, first
22:26	princeso	,(type .123456789012345678901234567890)
22:26	amalloy	i think it's a reasonable shortcut to try to take, but if anything goes wrong with that shortcut i'd just abandon it and do it by hand
22:26	clojurebot	#error {\n :cause "Unable to resolve symbol: .123456789012345678901234567890 in this context"\n :via\n [{:type clojure.lang.Compiler$CompilerException\n :message "java.lang.RuntimeException: Unable to resolve symbol: .123456789012345678901234567890 in this context, compiling:(NO_SOURCE_PATH:0:0)"\n :at [clojure.lang.Compiler analyze "Compiler.java" 6704]}\n {:type java.lang.RuntimeException\n...
22:27	justin_smith	princeso: numbers can't start with a . in clojure, you need 0.
22:28	princeso	justin_smith that makes sense
22:29	justin_smith	I think it's partially because we use . so much for interop stuff? dunno