#clojure – 2015-03-22

2015-03-22

04:41	ane	is there a shorter way around this: (map (fn [sym] ((resolve sym) a b)) symbols)
04:42	opqdonut	well you can always say (map #((resolve %) a b) symbols)
04:42	opqdonut	but that's it I guess
04:47	ane	hm, yes. so there's no handy "anti-quote" macrothing to do what resolve does?
04:50	amalloy	how could it be a macro? you're asking it to operate on data the exists at runtime
04:52	ane	oh, not a macro
04:53	opqdonut	if you use quote, you'd have to couple it with eval
06:41	dysfun	what's the easiest way to deal with temporary file generation in clojure?
06:42	dysfun	hrm, me.raynes.fs looks easy enough
08:24	spinningarrow	The docstring for empty? says to use seq instead of (not (empty? ...)) but seq doesn't return a boolean. So is that still the right approach when writing a predicate?
08:25	Bronsa	spinningarrow: clojure generally doesn't care about true/false, truthy/falsy is usually enough
08:25	spinningarrow	Bronsa: so if a function returns truthy/falsy, it is still considered a predicate, I suppose?
08:26	gfredericks	yeah people do it all the time
08:26	Bronsa	spinningarrow: eh, no it's not strictly a predicate but we use it as a predicate all the time
08:27	gfredericks	hello Bronsa
08:27	hyPiRion	It sort-of depends – I tend to be a bit careful about that
08:27	hyPiRion	get and nth may return nil, for instance
08:27	spinningarrow	ah cool. Sorry if that was a stupid question, but I was doing a clojure course and the midje tests were explicitly checking if the predicate returned `true` or `false`. Was just wondering if that's common :)
08:27	Bronsa	gfredericks: o/
08:27	gfredericks	\o
08:27	hyPiRion	(for correct lookups)
08:27	hyPiRion	s/correct/successful/
08:28	spinningarrow	hyPiRion: yeah, that's a good point too!
08:31	sahil	exit
08:31	spinningarrow	so I guess that generally it's fine, but something to be careful about
08:45	hyPiRion	yeah, it depends on what the function can return
08:45	hyPiRion	you might get false negatives
08:47	gfredericks	(defn does-has? "Returns :nope if m contains k and :yep otherwise." [m k] ...)
08:47	gfredericks	I think I got that backwards
08:49	spinningarrow	gfredericks: haha
08:50	spinningarrow	well, thank you guys very much for all the clarification! I shall mess around some more in clojure-land gfredericks hyPiRion Bronsa
08:51	hyPiRion	gfredericks: just do (alter-var-root #'does-has? complement)
08:55	gfredericks	hyPiRion: no we're pretty much stuck with it; don't want to make breaking changes
08:55	bcm	spinningarrow: what clojure course is that?
08:55	hyPiRion	gfredericks: oh okay then
08:56	spinningarrow	It's this one - 'Functional programming with Clojure' (http://mooc.fi/courses/2014/clojure/)
08:58	bcm	Clojure is listed as an intermediate language. There isn't that much more to setup is there?
08:59	bcm	This course looks pretty cool
08:59	bcm	really well done use of bootstrap, too
09:49	edeferia	hi. question for the group: i would like know the most idiomatic way of doing the following: i have a list of functions (literaly as a list) and would like to use the thread macro on it. how?
09:50	justin_smith	edeferia: macros work before the compilation stage, they are not a runtime thing
09:51	justin_smith	if the list is known before runtime, you can make a macro that injects that list into a threading macro
09:51	justin_smith	otherwise, you can use reduce
09:51	justin_smith	(to get most of the same functionality, but at runtime)
09:51	edeferia	ah, got it. understand. so basically unroll the list in a macro that uses ->
09:51	justin_smith	`(-> ~x ~@fs)
09:52	justin_smith	inside a macro
09:52	justin_smith	but only works if fs are known when compiling
09:52	edeferia	they are.
09:52	hyPiRion	Well, if you have the list at compile time, why not write (-> x f-1 f-2 f-3) ?
09:53	gfredericks	yeah -> is more for readability; not so useful with macros
09:53	hyPiRion	Otherwise you can just use (defn thrush [x fs] (reduce #(%2 %1) x fs))
09:53	edeferia	hyPiRion: because although the list of functions is known, their sequence can change from call to call
09:54	justin_smith	hyPiRion: yeah, that was the reduce version I was suggesting above
09:54	gfredericks	can't use -> then
09:54	gfredericks	or
09:54	gfredericks	um
09:54	gfredericks	depends on what "call to call" means
09:55	edeferia	multiple invocations of the equivalent of (-> init (…)) would have different ordered set of functions in (…)
09:56	hyPiRion	edeferia: I'd say to go with a function first (thrush), as justin_smith originally suggested.
09:56	hyPiRion	A macro won't give you any notable benefits here, at least not initially
09:56	gfredericks	and has drawbacks
09:56	gfredericks	like it's tricky to reason about
09:56	gfredericks	case in point, I still can't tell even with your last clarification whether this would work
09:57	justin_smith	right. The macro is helpful for readability, and using it programmatically like that avoids that benefit.
09:57	edeferia	agree. thank you all for the assistance. i will try justin_smith’s suggestion. thanks again.
11:06	Manaphy91	Hi! Is there a way to create a non mutable tree, where nodes have parents and childs, with deftype?
11:07	justin_smith	Manaphy91: doubly linked and immutable doesn't work
11:08	justin_smith	Manaphy91: if you don't need parent links from the children, then yeah, you can do that with deftype
11:08	Manaphy91	mmmh, I suppose it but I would like to ask it for a confirm... I dont linke to use loking manually but I think it's what I will do...
11:08	justin_smith	loking?
11:08	gfredericks	locking
11:08	justin_smith	why would you need to lock anything?
11:10	Manaphy91	I would like to use this structure concurrently.... I can use atom for a race safe access...
11:10	justin_smith	Manaphy91: I thought you said it would be immutable
11:11	Manaphy91	Yes!!
11:11	justin_smith	OK, atoms don't use locking at all, and they wrap an immutable datatype
11:12	Manaphy91	Ok, thanks, I will try something!!
11:13	hyPiRion	Manaphy91: bbloom had a talk on immutable graphs in Clojure: https://www.youtube.com/watch?v=YgvJqWiyMRY
11:14	Manaphy91	hyPiRion: Thanks!!
11:14	hyPiRion	at 6:10 specifically
12:22	justin_smith	hyPiRion: that bbloom talk is great, it makes me want to make an adjacency-list based follow up
12:23	justin_smith	(adjacency lists being a way to get a super general reification of traversal context, even handling cycles and cross references)
12:25	hyPiRion	yeah, it's good
12:34	spradnyesh	why do i see *[org.clojure/tools.nrepl "0.2.6" :scope "test" :exclusions [[org.clojure/clojure]]]* in "lein deps :tree" even though my project.clj explicitly lists *[org.clojure/tools.nrepl "0.2.8"]* as a dependency?
12:34	justin_smith	spradnyesh: put the tools.nrepl dep under :dev
12:35	spradnyesh	justin_smith: thanks for the pointer, let me check that
12:35	hyPiRion	spradnyesh: because bugs
12:38	spradnyesh	justin_smith: worked. thanks :)
13:15	mmg	I’m having some basic macro behavior that I don’t get and I’m trying to understand why. I started with a macro I didn’t expect to work but it’s failing in a way I wouldn’t have guessed:
13:15	mmg	(defmacro macro-foo
13:15	mmg	[should-run arg]
13:15	mmg	(when should-run arg))
13:15	mmg	=> (macroexpand '(macro-foo bar baz))
13:15	mmg	baz
13:16	mmg	why does that just expand to baz when it can’t resolve bar at compile time?
13:16	justin_smith	because to the macro code, bar is a symbol
13:16	justin_smith	and symbols are truthy
13:16	mmg	oh....
13:16	mmg	thank you!
13:16	justin_smith	,(when 'ok :go)
13:17	clojurebot	:go
13:17	mmg	yeah I was thinking (when nil :go) => nil
13:17	mmg	I see what I did wrong now
13:17	mmg	thanks a ton
13:17	justin_smith	remember that a macro should return the form that you want to run
13:17	mmg	yeah, no I get that this was a dumb macro, I was just expecting failure to look different (shrug)
13:17	mmg	now I get why ;)
13:17	mmg	thanks again
13:18	justin_smith	np
13:19	justin_smith	amalloy: on the subject of bad commit histories, I have discovered that the combination of "git merge --no-commit" followed by cycles of "git add -p" and "git commit -m" is like magic
13:20	amalloy	hm. what is -m?
13:20	amalloy	something merge-related, but...
13:20	justin_smith	amalloy: oh, sorry, just supplying a message on the command line
13:20	amalloy	oh haha
13:21	amalloy	so, i do cycles of add -p, commit -m all the time. how does it interact with merge no-commit?
13:21	justin_smith	so I run git add -p, and select a "themed" group of changes, then commit them together
13:21	justin_smith	it's like a retroactive cure for add
13:21	justin_smith	amalloy: merge --no-commit means you get all the changes from the other branch, but not its history
13:22	amalloy	ah, i see now
13:22	justin_smith	so it's a way of rewriting the history of a series of messy changes because I have no attention span / focus
13:22	justin_smith	into an alternate, coherent history
13:23	amalloy	i'm still not quite sure how you end up with those changes on an alternate branch that you want to merge
13:24	justin_smith	amalloy: getting mixed up in the development process, and when it comes time to make a pr I realize the history is a total mess
13:24	amalloy	justin_smith: so you create another branch, and merge no-commit your disjointed changes?
13:25	justin_smith	right
13:25	justin_smith	then I turn them into sensible commit history
13:25	amalloy	i would usually just git reset before-dumb-changes, rather than git checkout -b some-branch before-dumb-changes
13:25	justin_smith	aha, yeah I think as usual git has multiple paths to glory
13:25	amalloy	yeah
13:27	justin_smith	oh, yeah, there was actually a reset step in there anyway (between the merge --no-commit and the add-p)
13:27	justin_smith	because even without the commits, it still stages things, so I need to reset to unstage so I can do selective staging
13:28	justin_smith	oh wow, there is a "reset -p", combine that with "add -p" and you have a nice little choose your own adventure
13:30	amalloy	justin_smith: also checkout -p
13:30	justin_smith	oh wow, nice
13:33	Glenjamin	i really like "git cola" for that sort of stuff - Qt based gui around staging/unstaging/comitting
13:35	oddcully	i use tig fiddling togetter proper commits. but i didn't knew about -p
13:35	justin_smith	magit does some of that stuff too, but I end up preferring to just use the terminal
13:35	justin_smith	yeah, -p is like a repl for building commits
13:36	Glenjamin	i dislike the linear nature of add -p
13:36	justin_smith	Glenjamin: like the way it gives you things in a predetermined order?
13:36	Glenjamin	guis are a bit better for random access, and easier to split hunks
13:36	Glenjamin	yes
13:37	kwladyka	hello, i am learning clojure, can you tell me why in this function http://pastebin.com/zTzhVfUy is "when pred"? What is the prupose of this line?
13:37	justin_smith	kwladyka: if pred is nil or false, the next line does not run
13:37	Glenjamin	kwladyka: in that scenario, (when) is equivalent to (if)
13:37	justin_smith	when is like if but only one branch
13:38	kwladyka	justin_smith yes i understand that but why is that necessary? It is example form book, it is index-of-any
13:38	justin_smith	kwladyka: if pred was nil or false, the next line would throw an exception
13:38	kwladyka	justin_smith i uderstand technical aspect "when pred" but i don't undrestand why author wrote this line
13:38	justin_smith	you'd have to look at the rest of the code to know why pred would be nil or false
13:39	justin_smith	I suspect index-filter is being called in a recursive context where pred might be updated on each loop, and might eventually be nil?
13:39	justin_smith	just a guess
13:39	kwladyka	hmm so in clojure there is no exception like try{} catch{} or something like that? Should i write in all places code prevent to exception?
13:39	justin_smith	kwladyka: there is
13:39	justin_smith	kwladyka: but that author is not using it
13:40	kwladyka	so it wouldnt be miskate if i dont write (when pred) in function like that? What is best pracice in clojure?
13:40	justin_smith	in general, exceptions (in any language) should be used for exceptional cases, not for control flow
13:41	justin_smith	we also have things like some-> that do chaining that short circuits if you hit nil
13:41	Glenjamin	kwladyka: many core functions are written to behave without exception when they receive nil
13:41	justin_smith	(doc some)
13:41	clojurebot	"([pred coll]); Returns the first logical true value of (pred x) for any x in coll, else nil. One common idiom is to use a set as pred, for example this will return :fred if :fred is in the sequence, otherwise nil: (some #{:fred} coll)"
13:41	justin_smith	(doc some->)
13:41	Glenjamin	,(get nil)
13:41	clojurebot	"([expr & forms]); When expr is not nil, threads it into the first form (via ->), and when that result is not nil, through the next etc"
13:41	clojurebot	#error{:cause "Wrong number of args (1) passed to: core/get", :via [{:type clojure.lang.ArityException, :message "Wrong number of args (1) passed to: core/get", :at [clojure.lang.AFn throwArity "AFn.java" 429]}], :trace [[clojure.lang.AFn throwArity "AFn.java" 429] [clojure.lang.AFn invoke "AFn.java" 32] [sandbox$eval69 invoke "NO_SOURCE_FILE" -1] [clojure.lang.Compiler eval "Compiler.java" 6784] ...
13:41	jdeisenberg	Is there a way to specify the version of a template that you want to use in Leiningen?
13:41	Glenjamin	oh, whoops - bad example
13:42	justin_smith	jdeisenberg: no, a real peeve of mine actually
13:42	justin_smith	,(get nil :anything)
13:42	clojurebot	nil
13:42	Glenjamin	that's what i meant :)
13:42	Glenjamin	clojure mostly gives you back nil instead of throwing null pointer exceptions
13:43	jdeisenberg	justin_smith: Thanks. Maybe I should look at Leiningen and see if I can figure out how to add that. In my copious spare time, of course :)
13:43	justin_smith	haha, of course
13:44	kwladyka	ok so if i undrestand best practice in clojure is: if function can do what should do return value, in other case return nil?
13:44	justin_smith	that's the usual thing, yeah
13:45	jjttjj	what are people's preferred clojure dynamoDB clients these days?
13:46	jjttjj	I guess I prefer operating on a higher level than having more fine tuned control, if that's a factor
13:46	kwladyka	thx!
14:09	geekyvin_	Hey Guys, I've created a simple web-app in Clojure and deployed it in a remote server. but the problem is my application doesnt seem to serve resource files such as css/javascripts...etc. I couldnt figure out why.
14:09	geekyvin_	I tried jetty with nginx and tomcat7 with nginx
14:09	geekyvin_	this is my project.clj
14:09	geekyvin_	(defproject test_web_app "0.1.0-SNAPSHOT"
14:09	geekyvin_	:description "FIXME: write description"
14:09	geekyvin_	:url "http://example.com/FIXME"
14:09	geekyvin_	:dependencies [[org.clojure/clojure "1.6.0"]
14:09	geekyvin_	[compojure "1.1.6"]
14:09	geekyvin_	[hiccup "1.0.5"]
14:09	clojurebot	It's greek to me.
14:09	geekyvin_	[ring-server "0.3.1"]]
14:09	geekyvin_	:plugins [[lein-ring "0.8.12"]]
14:10	geekyvin_	:ring {:handler test_web_app.handler/app
14:10	justin_smith	geekyvin_: don't do that
14:10	geekyvin_	:init test_web_app.handler/init
14:10	geekyvin_	:destroy test_web_app.handler/destroy}
14:10	justin_smith	geekyvin_: stop
14:10	geekyvin_	:profiles
14:10	geekyvin_	{:uberjar {:aot :all}
14:10	geekyvin_	:production
14:10	geekyvin_	{:ring
14:10	geekyvin_	{:open-browser? false, :stacktraces? false, :auto-reload? false}}
14:10	geekyvin_	:dev
14:10	geekyvin_	{:dependencies [[ring-mock "0.1.5"] [ring/ring-devel "1.3.1"]]}})
14:10	geekyvin_	Opps...sry
14:10	geekyvin_	Opps...
14:10	geekyvin_	Oops..
14:10	andyf	Gist or paste please
14:10	justin_smith	geekyvin_: how are you accessing the resource files?
14:11	geekyvin_	its a simple web-app created with the command lein new compojure-app <web-app-name>
14:12	justin_smith	geekyvin_: that didn't answer my question
14:12	geekyvin_	the statics files are called from html
14:12	justin_smith	what specifically is being done to fetch those resources
14:12	justin_smith	are you using wrap-resource?
14:12	justin_smith	wrap-file?
14:13	geekyvin_	right, I found then but couldnt really find how to use them.
14:14	geekyvin_	shld the :wrap-resource be in project.clj or in my handler?
14:14	justin_smith	wrap-resource is a function, and it should be in your handler
14:18	geekyvin_	ok let me try that.
14:18	geekyvin_	thank Justin.
14:19	justin_smith	np
14:20	gfredericks	"in your handler" in the sense that it's a middleware you should use
14:20	justin_smith	right, "around" would be the better preposition there
15:39	michaelr`	anyone here uses bidi?
15:39	michaelr`	err
15:42	michaelr`	i have one handler which handles both :post and :delete requests, the url of the first is /something and the second is /something/1. is there any way that I can unmatch for both urls from the same handler?
15:45	michaelr`	both routes are guarded with request methods, essentially I'd like to parametrize url generation with the request method
15:49	arrdem	Anyone messed with Racket and care to comment on it?
16:02	justin_smith	arrdem: very clean, a great language for pedagogy, not a huge library ecosystem (like most schemes)
16:02	gfredericks	technomancy likes it
16:02	gfredericks	for...kids
16:03	justin_smith	also, the way you can explicitly choose a language dialect in your source code is kind of cool
16:04	andyf	I find its mob associations make it scary to use. License enforcement by limb mangling?
16:06	justin_smith	andyf: it follows a proud tradition of "scheme" dialect names. See also gambit, larceny, guile
16:06	justin_smith	and some of them get a bit more conceptual, like stalin
16:06	andyf	Holy cow. We may have unearthed a conspiracy here
16:19	ben_vulpes	i've been away from clojure webapp development for a while (9 mos? feels like eternity...). is chestnut awesome or will it be really painful in novel ways after six months?
16:21	_2_Mini	Hola a todos
17:00	tolstoy	Is there any way to avoid this thing: 'Reflection warning, clojure/data/priority_map.clj:215:19 - call to method equiv on java.lang.Object can't be resolved (no such method).'
17:00	tolstoy	Not sure why it's showing up all of a sudden.
17:01	tolstoy	Maybe some interaction with 'aleph'? Hm.
17:01	gfredericks	that's interesting
17:01	tolstoy	Using :global-vars {warn-on-reflection false} doesn't help.
17:02	tolstoy	Also: 'Reflection warning, clojure/core/memoize.clj:72:23 - reference to field cache can't be resolved.'
17:02	gfredericks	tolstoy: are you using priority-map directly? or is aleph requiring it?
17:03	gfredericks	it looks like there's a "fix reflection" commit in their history included in the latest release
17:03	tolstoy	I'm not.
17:03	tolstoy	If it's a lib, I don't see it in "lein deps :tree".
17:04	gfredericks	what version of aleph are you using?
17:04	tolstoy	"0.4.0-beta3"
17:06	tolstoy	Related: http://permalink.gmane.org/gmane.comp.java.clojure.aleph/693
17:14	tolstoy	Ah, I see it now. core.async is indeed using priority_map.
17:15	tolstoy	What's puzzling is that the latest release is from Sep 2014.
17:16	tolstoy	Ah. Update to the latest priority map, and that goes away.
17:17	tolstoy	No newer core.memoize, so out of luck there.
17:25	tolstoy	http://dev.clojure.org/jira/browse/CMEMOIZE-13
18:17	_1_Andrz8766	hey
18:21	_1_Andrz8766	hello?
18:21	clojurebot	BUENOS DING DONG DIDDLY DIOS, fRaUline _1_Andrz8766
18:21	_1_Andrz8766	how do you use this thinh
18:24	justin_smith	_1_Andrz8766: are you new to IRC?
18:26	Bronsa	(inc clojurebot)
18:26	lazybot	⇒ 48
19:53	gfredericks	(inc lojurebot)
19:53	lazybot	⇒ 1
20:01	justin_smith	I may have done something silly. I am working on a data structure lib that represents graphs natively as adjacency lists, and I have functions that attempt to turn a graph into a tree or list
20:01	justin_smith	and the list one is just a lazy list that follows a random outgoing edge at teach step until there are no more outgoing edges left
20:02	justin_smith	so running it twice will give you two different outputs for any graph that can't be represented as a singly linked list
20:02	justin_smith	maybe that's useful?
20:02	justin_smith	if the graph has no non-cyclic paths, you get an infinite lazy-seq
20:10	gfredericks	has anybody made an arithmetic lib for dealing with pretend unsigned bytes/ints/longs?
20:10	gfredericks	presumably by using primitives but doing the arithmetic differently
20:10	justin_smith	gfredericks: that seems like a natural thing, like in some java lib that asists in jni stuff or something
20:11	gfredericks	I think java 8 might have related things
20:11	gfredericks	but that doesn't help for writing fluent clojure
20:12	gfredericks	I was also thinking that anybody who intentionally uses bigdecimal might find a set of arithmetic functions restricted to bigdecimal useful
20:12	gfredericks	to ensure they never accidentally degrade to doubles
20:13	justin_smith	gfredericks: hmm, maybe you could even keep the arithmetic the same (but only do unchecked operations) and just override like >, <, and the print method
20:13	justin_smith	because with twos compliment the rest should just work until you hit over / under flow
20:13	gfredericks	gotta be careful with shifting too
20:14	justin_smith	ahh, yeah
20:19	gfredericks	justin_smith: multiplication wouldn't work right would it?
20:20	gfredericks	without a separate impl I mean
20:28	justin_smith	"The two's-complement system has the advantage that the fundamental arithmetic operations of addition, subtraction, and multiplication are identical to those for unsigned binary numbers (as long as the inputs are represented in the same number of bits and any overflow beyond those bits is discarded from the result)."
20:28	justin_smith	that's why I was thinking it would be elegant
20:28	justin_smith	basic ops just stay the same (and thus also remain as efficient)
20:29	gfredericks	oh wow I didn't know it worked for multiplication as well
20:29	gfredericks	the more I think about it the more skeptical I am
20:30	gfredericks	thinking about the highest bit, and what determines it in an unsigned mult
20:30	justin_smith	gfredericks: I think overflow would just "accidentally" do the right thing
20:31	justin_smith	but that's easy to test with some unchecked math, or even by hand
20:32	gfredericks	where did you get this quote
20:32	justin_smith	wikipedia
20:32	gfredericks	you can't trust that did you know anybody can edit it
20:32	justin_smith	I've heard
20:32	gfredericks	it's like a button on there; you can make it say whatever you want!
20:33	justin_smith	gfredericks: but that wasn't my original source, it was just easier to look up :)
20:34	gfredericks	in multiplication the highest bit in the result is dependent on like every bit of the inputs
20:34	gfredericks	but in signed multiplication that bit has to be the correct sign of the result
20:35	gfredericks	but if it's also dependent on every bit of the inputs I should be able to twiddle the bits of the inputs (without changing their sign) to manipulate the sign of the outputs
20:35	gfredericks	s/outputs/output/
20:36	justin_smith	gfredericks: the two's complement signed multiply and the unsigned multiply, when applied two to numbers with the same bit representation, are guaranteed to result in the same bits in the output
20:36	justin_smith	it's the same operation on the bit level
20:36	gfredericks	you're just stating the position I'm arguing against, right?
20:37	justin_smith	I'm telling you a fact about how two's complement multiply works
20:37	gfredericks	yes I believe you that it's true but it's also totally impossible and I'm trying to explain why
20:38	justin_smith	gfredericks: it's because what is overflow on one side, is a correct multiply on the other
20:38	justin_smith	it's a lot easier to overflow with signed multiply
20:38	gfredericks	sure, but I'm focusing on the value of the highest bit
20:38	gfredericks	after truncating overflow
20:39	gfredericks	which is a bit that must be determined by virtually every bit of the inputs I think
20:40	justin_smith	OK - they are identical for non-overflowing operations, and are respectively correct for ops that don't overflow (there are some signed results that are overflows, that are not overflows in the unsigned version)
20:40	gfredericks	huh?
20:41	justin_smith	I'm going to try to work this out in a simplified model, like with a three bit number
20:41	justin_smith	ok, maybe four bit
20:41	gfredericks	wikipedia says something about having to double the precision beforehand
20:44	justin_smith	if you want to guarantee you don't overflow, sure - double precision and extend the sign bit
20:47	gfredericks	so what you said earlier is that multiplication doesn't work if the ops are large enough to overflow, right?
20:47	gfredericks	which means the sentence in the wikipedia intro is misleading?
20:49	gfredericks	I just did 7+(-3) and got -5
20:49	gfredericks	er 7*(-3)
20:49	gfredericks	which is the correct sign actually
20:50	gfredericks	now that I think about it I don't know what you're supposed to expect semantically from overflow of signed multiplication
20:50	gfredericks	is it equivalent to multiplication mod something somehow?
20:51	gfredericks	this must be my problem I don't actually know what I think it's supposed to do; I just assumed that signs should be well-behaved, but maybe not
20:59	justin_smith	gfredericks: so I just wrote out all the five bit numbers in standard / 2's complement, and picked a random multiplication to show that once you truncate overflowed bits, the output is the same
20:59	justin_smith	http://i.imgur.com/tZX9uuI.jpg
20:59	justin_smith	sorry it's a little sloppy - on the left is bits - unsigned / signed
20:59	justin_smith	on the right is signed on top, then bits, then unsigned
21:00	justin_smith	with the two truncated bits bracketed
21:02	gfredericks	justin_smith: but what happens when the signed op result is semantically out of range?
21:02	gfredericks	e.g., -5 * 7
21:03	justin_smith	one second, scribbling
21:03	gfredericks	I demand moar photo graphs
21:04	gfredericks	faxed to me
21:04	justin_smith	haha
21:05	john2x	there's no date generator in test.check?
21:06	gfredericks	nope
21:07	gfredericks	what kind of distribution would you want on that?
21:07	john2x	just completely random dates. hmm I guess a constant date would work just as well for my current purposes.
21:07	gfredericks	is 19487917373191-02-28 a date?
21:08	john2x	heh yeah.. that could get tricky
21:08	gfredericks	we've got a lot of design work to do on good numeric generators
21:08	gfredericks	which would probably help with what you're wanting
21:09	gfredericks	in the meantime if you think of something obviously generally useful I can probably put it in test.chuck
21:13	justin_smith	gfredericks: with 277, / -57 they still match for the last five bits (which is all the matters since I was doing five bit two's complement) and they only diverge where they overflow
21:13	justin_smith	both end in 11101
21:14	justin_smith	if cl-format wasn't a filthy liar when it comes to binary, I could show you that easily
21:14	justin_smith	*signed binary that is
21:16	gfredericks	,(mod (* 27 7) 32)
21:17	clojurebot	29
21:17	gfredericks	,(mod (* -5 7) 32)
21:17	clojurebot	29
21:17	gfredericks	which is -3 I think?
21:17	justin_smith	gfredericks: if you refer back to my jpg, it says yes
21:18	gfredericks	so I guess the semantics are multiplication mod 2^n and then wrapped around to negative as appropriate
21:19	gfredericks	and therefore the sign is chaotic
21:19	gfredericks	which is what I was intuiting before, but assumed that meant it wasn't working right
21:19	justin_smith	yeah, that sounds about right, and it is intuitive because multiplication is repeated addition
21:19	justin_smith	it's just that there are so many overflowing results you get overflowed overflow etc. :)
21:20	gfredericks	right, a chaotic sign
21:20	justin_smith	gfredericks: are you coming to clojure/west?
21:20	gfredericks	yep
21:21	gfredericks	booked my flights yesterday
21:21	justin_smith	cool
21:21	gfredericks	I've always lived closer to the east coast but I've attended clojure/west a lot more reliably
21:25	gfredericks	now I'm curious how you detect multiplication overflow
21:25	justin_smith	this will be my first clojure conference, and it will be crazy seeing all these people I know online in person
21:25	gfredericks	to the Numbers.javamobile!
21:25	justin_smith	gfredericks: you put the result in a double-sized result, then you check for any set bits
21:25	justin_smith	(in the extra sized side, of course)
21:26	justin_smith	gfredericks: but this is why I was saying before that it would be easy if you do unchecked ops :)
21:26	justin_smith	heh
21:26	justin_smith	because the unchecked results will match (while likely being useless to the application code)
21:26	gfredericks	you're just describing how to do it on a chip, no?
21:26	justin_smith	not just
21:27	justin_smith	you can do the same thing in an algorithm
21:27	gfredericks	Numbers.java is doing something clever
21:27	justin_smith	though I guess you would use a bigint instead of like a 128 bit int
21:27	justin_smith	interesting
21:27	gfredericks	omg there's a whole check for x == Long.MIN_VALUE && y < 0
21:27	gfredericks	maybe that's an edge case you can't detect otherwise
21:28	gfredericks	but then after multiplying it does a divide to see what happened
21:28	gfredericks	if (x&y)/y != x then overflow
21:28	gfredericks	x*y rather
21:28	justin_smith	fascinating, nobody's using those overflow bits on hardware more's the shame
21:29	justin_smith	s/bits/flags
21:29	justin_smith	I wonder if there are like experimental languages that use that feature
21:29	justin_smith	or if everybody's like "c doesn't support it, so we don't"
21:34	rksm	What's the most idiomatic way to read in a project.clj from a jar? I need the project map normally returned from leiningen.core.project/read.
21:34	gfredericks	is it normally in the jar at all?
21:35	gfredericks	you can probably get it into the jar with some :filespecs thing and then just read it with clojure.java.io/resource
21:36	gfredericks	might be a plugin that does this kind of thing already
21:37	justin_smith	gfredericks: rksm: checking a random jar, yeah I find a project.clj
21:37	justin_smith	now how do you get a specific version of a resource that is on the class path multiple times again? I always forget
21:38	gfredericks	a random jar? is it a lib?
21:38	justin_smith	yeah
21:39	justin_smith	gfredericks: yeah, I see them in each clojure lib I check
21:40	gfredericks	huh. well what do you know.
21:40	gfredericks	seems a little bit weird
21:40	rksm	Dealing with the classpath and getting content from a jar I managed to do. However, I want to duplicate none (or at least as little as possible) from leiningen.core.project/read (https://github.com/technomancy/leiningen/blob/master/leiningen-core/src/leiningen/core/project.clj#L950)
21:41	rksm	As read only accepts a file (not a jar URI or jar entry reader).
21:41	rksm	Hmm... how can I convert a buffered reader to a pushback reader?
21:41	tomjack	(java.io.PushbackReader. buffered-reader)
21:42	justin_smith	rksm: so how do I get a resource from a specific jar?
21:43	rksm	tomjack: yep, that works, thanks. now I can use read-raw :)
21:43	Draggor	Is there a tutorial to start with on clojure.test?
21:44	justin_smith	Draggor: the clojuredocs page for it is decent. It's a small library.
21:44	tomjack	justin_smith: (-> (Thread/currentThread) (.getContextClassLoader) (.getResources "foo") (enumeration-seq)) will give you a seq of URLs
21:44	rksm	justin_smith: I use jar files + jar entries for it: https://github.com/cloxp/clj-system-files/blob/master/src/main/clojure/rksm/system_files.clj#L100
21:44	justin_smith	tomjack: oh, nice
21:44	tomjack	I guess you can figure out which one is from which jar from there
21:44	tomjack	I stole that from the stuff in core.clj for data_readers.clj
21:45	justin_smith	tomjack: nice
21:46	tomjack	thank java that is possible..
21:46	Draggor	justin_smith: in particular looking to read about doing setup/teardown and setting a variable for tests
21:46	Draggor	if I were to not use fixtures I'd just do a let form I suppose
21:47	justin_smith	Draggor: typically there is very little setup/ teardown - with pure functions you do stubbing instead of mocking
21:47	justin_smith	and the stubbing can just be data literals and the occasional function literal
21:48	Draggor	justin_smith: sure, anywhere I can see an example of that?
21:48	justin_smith	Draggor: and my preferred approach is to have all my complex logic in pure functions (as much as possible), because stubbing to test all the logic is pretty trivial, then making the side effecting stuff as simple as possible so I can avoid / minimize stubbing
21:48	justin_smith	Draggor: hmm...
21:49	justin_smith	it would be good to have a go to example for that approach
21:55	rksm	Draggor: Take a look at how authentication in leiningen itself is tested. There is a credentials function that returns the content of ~/.lein/credentials.clj.gpg: https://github.com/technomancy/leiningen/blob/master/leiningen-core/src/leiningen/core/user.clj#L122 In order to test that without creating an actual file the var leiningen.core.user/credentials is re-defined at test time: https://github.com/technomancy/leiningen/blo
21:55	rksm	b/master/leiningen-core/test/leiningen/core/test/user.clj
21:55	rksm	Draggor: Take a look at how authentication in leiningen itself is tested. There is a credentials function that returns the content of ~/.lein/credentials.clj.gpg: https://github.com/technomancy/leiningen/blob/master/leiningen-core/src/leiningen/core/user.clj#L122 In order to test that without creating an actual file the var leiningen.core.user/credentials is re-defined at test time:
21:55	rksm	https://github.com/technomancy/leiningen/blob/master/leiningen-core/test/leiningen/core/test/user.clj
21:56	rksm	Most of the time you are best of with directly passing dependencies to your functions, though.
22:00	Draggor	I still feel like I'm missing something simple. I want a fixture that as setup, calls a pure function that returns an immutable object I'm then going to use in my tests. What does that look like?
22:02	justin_smith	Draggor: why does the fixture need to do that?
22:03	justin_smith	fixtures are for things with side effects, they don't pass anything to the tests
22:03	justin_smith	if it's immutable, can't it be a top level def or a let binding?
22:03	Draggor	Good point
22:03	gfredericks	,(def my-test-data 42)
22:03	clojurebot	#'sandbox/my-test-data
22:04	justin_smith	one moment, I'll upload what I am working on right now
22:04	gfredericks	I just made a computer somewhere on the internet keep the number 42 around for a little while just in case
22:07	justin_smith	https://github.com/noisesmith/adj/blob/master/test/org/noisesmith/adj_test.clj
22:07	justin_smith	I define some data structures, and do various things with them in each test
22:08	Draggor	Ahh, yes, it is that simple, thanks!
22:09	justin_smith	sadly, nothing in this project does side effects
22:09	justin_smith	though I guess I may add a db backed ns for persistent graph stuff eventually...
22:09	Draggor	What I'm doing, the side effect is user input which I can fake out in tests, the functions themselves are pure for doing the real work
22:10	justin_smith	right, and that's very simple to test
22:11	rksm	Draggor: And in case your input needs to change you can use dynamic scoping, however, be aware that this creates an indirect dependency between the dynamic state and your tests/code. https://gist.github.com/rksm/4a6c0116b32046290af3
22:12	rksm	And to just have a "template" test the are macro is useful: https://clojure.github.io/clojure/clojure.test-api.html#clojure.test/are
22:30	underplank	Hi all. Im using the fantastic clj-http lib, and I’ve been able to find the {:throw-exception false} parameter for the get function. But im using the request function to do arbitrary requests. Is there a way to pass the :throw-exception keyword in?
22:32	underplank	hmm thats wierd. it seems that the get is actually using request under the covers.
22:32	gfredericks	do (clojure.repl/source clj-http.core/request)
22:32	gfredericks	you can see a lot of opts there
22:32	gfredericks	last I checked they weren't otherwise documented
22:36	underplank	thanks i’ll take a look
22:47	ben_vulpes	man i am baffled. where does react.js come from in the chestnut/cljs templates?
22:49	tolstoy	ben_vulpes: I think it's pulled in as a dependency of [org.omcljs/om "0.8.8"].
22:49	tolstoy	It's in a jar file, if that helps.
22:49	ben_vulpes	hm.
22:50	tolstoy	[cljsjs/react "0.12.2-5"]
22:51	tolstoy	Last I remember (it's been a while) there's a deps.cljs in the jar and other such conventions.
22:51	ben_vulpes	i was using an ancient version of om, apparently.
22:52	spinningarrow	Which text editor or IDE do most people use for Clojure? (hope I'm not starting a war - just genuinely curious)
22:53	srid	Emacs
22:53	justin_smith	spinningarrow: emacs, though cursive (an intellij idea plugin) likely has the best tooling
22:54	srid	but I'm open to learn of better IDEs for Clojure
22:54	ben_vulpes	i know a guy who uses vim/fireplace
22:55	srid	Cursive will be available as an IntelliJ plugin for use with the Community or Ultimate editions, as well as a standalone Clojure-focused IDE. It will be a commercial product, at a similar price point to PyCharm or RubyMine.
22:55	srid	- https://cursiveclojure.com
22:55	justin_smith	srid: yes, but it is available for free right now
22:55	srid	so it is not production ready
22:55	justin_smith	srid: it's more complete than any of the other options
22:57	ben_vulpes	is emacs even production ready?
22:58	justin_smith	ben_vulpes: cider sure the hell isn't, it still changes the abi all the time
22:58	ben_vulpes	tolstoy: i should expect to see react.js get compiled onto my clojurescript path, right?
22:58	ben_vulpes	just by virtue of using org.omcljs/om "0.8.0"
22:58	ben_vulpes	or am i missing something here.
22:59	tolstoy	ben_vulpes: I think (depending on cljs compiler configuration), it gets merged into your main.js file.
22:59	ben_vulpes	hm.
22:59	tolstoy	ben_vulpes: For me, it so often "just works" that I've forgotten about it. ;)
23:00	ben_vulpes	fwiw, i get out/goog/base.js
23:00	ben_vulpes	"works on my machine..."
23:01	tolstoy	Building a project to see where it goes.
23:01	tolstoy	I have a "dev" task which does the source map and optimizations :none thing.
23:02	tolstoy	goog.addDependency("../react.inc.js", ['cljsjs.react'], []);
23:02	tolstoy	It's in my "out" directory.
23:02	ben_vulpes	when you say "dev" task, are you referring to a :dev key in your :builds vector?
23:02	ben_vulpes	er
23:02	tolstoy	Yes.
23:03	ben_vulpes	a build in the build vector with a "dev" value for the :id key, more accurately.
23:03	Draggor	rksm: are looks perfect, thanks
23:03	tolstoy	Yeah: {:builds [{:id "dev" ;; but I get what you mean.
23:03	tolstoy	I've defined an output dir as resources/public/out and react.js gets put in there.
23:04	tolstoy	Extracts from the jar, I imagine.
23:06	ben_vulpes	is it possible that the clojurescript compiler thinks it already copied the react file?
23:06	tolstoy	When I do a "release" build (:optimizations :whitespace), react.js is embedded at close to the top of the resulting "single" main.js file.
23:06	tolstoy	Are you using 0.8.8?
23:07	ben_vulpes	[org.omcljs/om "0.8.8"]
23:09	tolstoy	Oh. You're experiencing an issue or something?
23:09	ben_vulpes	it looks like om etc aren't terribly willing to compile.
23:10	tolstoy	Here's my extremely minimal build config, if that helps.
23:10	ben_vulpes	i just blew away my resources/public/out directory by hand, reran lein cljsbuild auto, and it did not drop goog/**
23:10	tolstoy	https://www.refheap.com/98782
23:11	ben_vulpes	looks pretty identical to mine.
23:11	tolstoy	You have the most recent cljs?
23:11	tolstoy	Yeah, I'm not exploiting a whole lot on CLJS. ;)
23:11	ben_vulpes	yeah, let me restart my jvm
23:12	tolstoy	Actually, I don't have the most recent stuff (this is an EOL project).
23:13	ben_vulpes	hrm.
23:14	ben_vulpes	well i'm rolling back to 0.8.0 rc1 to see if it'll compile google closures etc
23:14	underplank	Ok, so I have a ring server that is being run. I want to se a break point in a handler and use a debug repl to have a look around and step in and out of functions. What is the best way to do this?
23:15	tolstoy	Does "lein deps :tree" reveal anything troubling?
23:16	tolstoy	Latest lib updates produce some interesting warnings, but it all works with regard to react.js.
23:17	ben_vulpes	lein figwheel screamed about misconfigured output-dir path, interestingly.
23:18	tolstoy	Ah, figwheel. Maybe comment that out and see?
23:19	ben_vulpes	now that i think about it, figwheel was how i compiled assets first.
23:19	ben_vulpes	but from inside a repl. i was working to shoehorn figwheel-from-repl into a component
23:20	tolstoy	There's been a lot of repl thrash lately. I think bhauman has been keeping up, but I've given up on it for the duration.
23:20	ben_vulpes	sigh
23:20	ben_vulpes	good to know, thanks.
23:20	tolstoy	According to dnolen, all the repls work great (from Emacs) using an inferior-lisp mode, but not cider.
23:20	ben_vulpes	(classic me, though: "this workflow isn't right! as part of spinning this project up i will make it do the RIGHT THING")
23:21	ben_vulpes	mk, that did it.
23:21	ben_vulpes	:output-dir "resources/public/js/out/"
23:22	tolstoy	Heh. For me, it's, "Surely I need to get a handle on line numbers properly formatted and dimmed rather than my actual hobby project I love working on."
23:22	ben_vulpes	okay, commit.
23:24	tolstoy	The QuickStart guide might interest you, if you're into back-to-basics on a path to building up again.
23:29	ben_vulpes	clojurescript quickstart?
23:38	tolstoy	Yeah.
23:39	tolstoy	https://github.com/clojure/clojurescript/wiki/Quick-Start
23:42	ben_vulpes	yeah, i'm like 80% competent with all of that
23:42	ben_vulpes	lol okay i got figwheel running awesome
23:42	ben_vulpes	now i'm just going to let go of it not being integrated in my component workflow for now, and see if i can hammer out a few om buttons or something
23:42	ben_vulpes	woo
23:42	ben_vulpes	thanks tolstoy
23:43	tolstoy	Excellent! Nah, I just mention it because cljs dev has been improving a lot lately, and it's always nice to go back to take stock. (Like re-reading clojure.core API every once in a while.)
23:48	ben_vulpes	definitely good ideas.