#clojure – 2011-05-05

2011-05-05

01:06	stirfoo	/quit
01:06	stirfoo
01:30	bhenry	before i write it, is there already a macro or function that will print and return the result of what's inside it? i.e. (prn-ret {:a 1}) will print {:a 1} but also return {:a 1} instead of nil like prn.
01:39	amalloy	bhenry: there are a few
01:39	amalloy	one in cc.logging, but it logs instead of printing iirc
01:40	amalloy	bhenry: https://github.com/amalloy/amalloy-utils/blob/master/src/amalloy/utils/debug.clj is mine
01:40	amalloy	though if you want a super-simple one you can just ##(doto (inc 3) println)
01:40	sexpbot	⟹ 4 4
02:17	thorwil	semperos: thanks for the mail, but i'm well aware of enlive'e substitute. the problem is extracting the content of the tag that is to be replaced ;)
02:17	semperos	thorwil: I figured
02:26	semperos	thorwil: I think you might find your answer by looking at the implementation of the content fn
02:26	semperos	as enlive deals with the HTML as maps, :content is just one of the keys
02:26	semperos	:tag is another
02:27	semperos	you can probably put together your own little fn in the same form, replacing the :tag instead of the :content for the target enlive node
02:27	thorwil	good point.
02:28	thorwil	i saw mention of a let-select function on the enlive list, so i have a few things to try now. ty
03:09	thorwil	given (def test-html (en/html-snippet "<p><span>Previous</span> <span>Next</span></p>"))
03:09	thorwil	((en/transformation [:span] ((fn [& values] #(assoc % :tag (en/flatten-nodes-coll values))) "a" )) test-html)
03:09	thorwil	comes close, but i need a way to insert an :a
03:11	thorwil	of course! ((en/transformation [:span] ((fn [& values] #(into % (en/flatten-nodes-coll values))) {:tag :a} )) test-html)
04:25	clgv	Are there any LISP conferences or deadlines for LISP related journals for the remaining year that one should know about?
04:37	fliebel	Is the clojure reader extensible?
04:37	ejackson	fliebel: no reader macros
04:38	fliebel	ejackson: Waiting for the new compiler, or by design?
04:38	clgv	fliebel: in a repl context you can wrap around it by passing an own function with :read to clojure.main/repl
04:38	ejackson	by design - Rich believes they lead to fragmentation and difficulties.
04:40	fliebel	clgv: What do you mean with :read?
04:41	clgv	fliebel: if you are shooting for reader macros like ejackson said then I guess it wont help you. didnt read that in time ;)
04:42	fliebel	clgv: But what will it help with?
04:44	clgv	fliebel: as far as I thought about it - you can define own commands for your repl that do not need to be clojure functions or macros. I used it for some stuff with the debug-repl
04:45	fliebel	Meh, it was a bad idea anyway probably… I'm thinking about templating languages.
04:45	clgv	that means?
04:46	fliebel	Well… scala has xml literal support ;)
04:47	clgv	you could build a clojure DSL though - it just has these additional parantheses ;)
04:48	fliebel	clgv: that'd be hiccup, but then uglier.
04:49	fliebel	Are there any other exotic ones besides enlive? I mean, anything other than PHP style.
04:51	clgv	hmm is it really desirable to use literal xml in programs? I don't have an opinion on that myself atm...
04:51	fliebel	clgv: Not at all! Just a silly alternative to hiccup.
04:51	clgv	fliebel: ah your playing around and searching limits? ;)
04:52	fliebel	probably :) But the end goal is to find some really awesome templating
05:04	thorwil	from the outside, most templating engines seem to differ mainly in how/where to handle logic.
05:05	fliebel	thorwil: In that case, I'm in the no-logic camp. But that is only the start. I'm not all to happy with introducing a new mini language at all.
05:06	fliebel	So I say, templates should be html and clojure, .-.-.- (full stop)
05:07	thorwil	that's why i really like enlive. no logic in templates, no new language (macros are on the edge, admittedly)
05:08	fliebel	thorwil: Yea, Enlive is great, but I was wondering if there was any competition in this space.
05:09	thorwil	if there's anything that might start to bug me, it will likely be the inroduction of javascript. especially in the "reverse-ajax/comet" (ain't those silly terms?) case
05:09	fliebel	thorwil: What?
05:10	thorwil	fliebel: the server triggers client code case
05:11	fliebel	thorwil: Yea, what about it? I haven't seen Enlive do that, which is what my confusion is about.
05:12	thorwil	fliebel: so far it only means that i have to insert tokens generated on the server into the JS
05:13	thorwil	i do that with selecting the nth script tag and en/prepend to insert a single JS line
05:13	fliebel	oh, that :)
05:14	thorwil	a less explicit way to handle that would be nice. the Erlang web framework Nitrogen seems to be really great at that
05:14	thorwil	(but has only very rudimentary templating)
05:15	thorwil	fliebel: i think among other more interesting template engines are http://genshi.edgewall.org/ and http://beebole.com/pure/
05:16	fliebel	genshi is nice
05:27	andrewclegg	morning all... I'm trying to create a Date with no arguments like this: (def now (Date.))
05:27	andrewclegg	but I get thisL
05:27	andrewclegg	:
05:27	andrewclegg	java.util.Date cannot be cast to clojure.lang.IFn
05:28	andrewclegg	Am I losing the plot? :-)
05:29	Chousuke	that should work just fine
05:29	andrewclegg	it's not :-(
05:30	Chousuke	how are you using now? :/
05:30	Chousuke	also are you sure you didn't typo something
05:30	andrewclegg	I'm passing it to a function like this:
05:30	andrewclegg	(crap-date-format now)
05:30	andrewclegg	which isL
05:31	andrewclegg	:
05:31	andrewclegg	(defn crap-date-format [date]
05:31	andrewclegg	"TODO: make this less crap."
05:31	andrewclegg	(apply str (take 19 (.toString (date)))))
05:31	andrewclegg	oh hang on
05:31	Chousuke	there's the problem
05:31	andrewclegg	I see it, sorry
05:31	Chousuke	btw, you can use subs to get a substring
05:31	andrewclegg	err, thanks :-)
05:31	andrewclegg	oh, I hadn't seen that, thanks
05:32	andrewclegg	still n00bing away
05:32	Chousuke	yeah, well subs is just a wrapper for the java method
05:32	andrewclegg	less typing is always good
05:40	andrewclegg	sorry chousuke, another Date q. -- should this work? (def date (java.util.Date. 0)) for 1970-01-01 00:00:00:000
05:40	andrewclegg	because I get No matching ctor found for class java.util.Date
05:42	Chousuke	andrewclegg: no idea, check the javadocs?
05:42	andrewclegg	public Date(long date): Allocates a Date object and initializes it to represent the specified number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.
05:42	andrewclegg	not casting to Long by default or something?
05:43	Chousuke	try doing (Date. (long 0)) then
05:44	andrewclegg	aha, thanks, didn't know you had to (or could) upcast ints to longs
05:44	andrewclegg	cheers for your patience
07:45	manutter	I have an enlive question:
07:46	manutter	In PHP I might do something like this -- $banner = "<div class='welcome-banner'>Logged in as $user_id</div>"; echo $banner;
07:46	manutter	Is there an easy way to do that using enlive?
07:47	fliebel	manutter: yes
07:47	manutter	I get the impression enlive wants me to use a template something like <div class='welcome-banner'>Logged in as <span id="user_id"></span></div>
07:47	manutter	but I want to replace $user_id in the middle of the content (and possibly in more than one place
07:48	manutter	)
07:48	fliebel	manutter: Well, the idea is that you add just the banner div with the default content, and insert that whole message using enlive. I think the content/replace do what you want.
07:50	manutter	content/replace sounds promising, I'm not familiar with that
07:51	manutter	I don't want to build the whole message in clojure because I'd like to use the template itself for internationalization, so the surrounding text will be different depending on the locale
07:52	pareidolia	Hi all! Is it possible to loop through a sequence (doseq/for) in blocks, not taking just one element? Thanks!
07:53	fliebel	manutter: idk, the span seems like the way to go.
07:53	fliebel	pareidolia: parition
07:53	fliebel	*partition
07:53	manutter	I'm not overly averse to the idea, just want to explore the alternatives :)
07:53	manutter	tks much
07:56	pareidolia	fliebel: Nice! I haven't seen it suggested in my search results, but it's right there in the api. Thanks!
09:46	bulters	is it possible to create an anonmyous 'multimethod'o
09:46	bulters	?
09:47	fliebel	bulters: Yes, with a lot of manual plumbing. Check the source for defmulti and defmethod. You just need to create the object yourself.
09:57	hyperboreean	what's the idiomatic way of storing paths to config/input files in clojure? I am using lein for building if this matters
10:06	jjido	hyperboreean: you can't use a Java File object?
10:06	raek	hyperboreean: if you want to read a resource file that is to be bundled with the program, you can put it in resources/ which is added to the classpath (and generated jar files) by lein
10:08	raek	hyperboreean: to load a resource on the classpath, do something like (require '[clojure.java.io :as io]) (-> "foo/bar.txt" io/resource io/reader)
10:08	raek	the file should be in resources/foo/bar.txt, relative to the project directory (which becomes foo/bar.txt relative to the class path)
10:09	raek	for resource file paths, / should always be used as the delimiter
10:10	raek	for ordinary file system paths in a platform independent way, construct the path with io/file by giving it the path segemts
10:10	raek	(io/file returns a java File object, which represents a file path)
10:14	raek	hyperboreean: the "resources" approach is typically used for things like icons and maybe config files for libraries the app uses.
10:20	pyr	hi
10:20	pyr	what is the accepted best way to deploy a ring/compojure app, in terms of performance ?
10:21	pyr	I'm using nginx in front of the jetty handler
10:21	pyr	AFAIK each request is mapped to a thread from a thread-pool, right ?
10:22	bulters	fliebel: thanks, will try it out :D
10:22	Belaf	Hello everybody.
10:23	cemerick	pyr: right; FWIW, there's not really any reason to proxy jetty or tomcat, unless you have other requirements that make that convenient.
10:24	pyr	cemerick: yep, i just don't wanna handle the rate limiting there
10:24	pyr	but point taken
10:24	pyr	cemerik: so this is basically the fastest way to deploy right now ?
10:25	cemerick	pyr: if by "fastest", you mean "least overhead", that's fine.
10:25	cemerick	There's not a lot of variation in Java webapp servers, really.
10:26	Belaf	I made an attempt at using gen-class to extend java.awt.image.RGBImageFilter. Now everything seems to work fine, only I have some doubts on the performance I get calling the new object's methods: they seem some 100 times slower than a function doing the same job (in my case very little). Is this to be expected?
10:26	pyr	cemerick: sometimes i wish there was an async_ring
10:26	cemerick	pyr: which would do what?
10:26	manutter	Belaf: are you using type hints on your function parameters?
10:27	pyr	cemerick: run requests and replies in a single thread
10:27	Belaf	Uh, no... should I give it a try?
10:27	cemerick	pyr: Wouldn't be too hard, but you wouldn't be able to deploy it in a servlet container like jetty or tomcat.
10:28	manutter	Belaf: I'm not much good at interop stuff, but whenever I hear people talking about slowdowns, type hints seem to come up a lot
10:28	pyr	cemerick: yes, it'd be a matter of adding some sugar on top of netty from what i gather
10:29	cemerick	pyr: Sure. I don't see the point, but then I don't do high-volume web stuffs.
10:30	Belaf	You mean adding type hints to the method definitions, right? I can try adding them, but I'm puzzled, as the methods already have their signature declared in the :methods gen-class declaration...
10:31	manutter	Belaf: could be, like I said I don't know all that much about interop stuff
10:31	manutter	Perhaps someone else can chime in? :)
10:32	Belaf	allright, I'll try experimenting with type hints, I need to learn something about them, anyway :)
10:32	Belaf	Thanks
10:32	clgv	Belaf: the first step should always be measuring to get to know where most of the time is spent and possibly lost ;)
10:32	pyr	cemerick: high volume is an application, websockets and bindings to/from QMS's are another
10:33	pyr	cemerick: i'll just shut up and code :)
10:33	cemerick	Belaf: FWIW, if you're only using your RGBImageFilter subclass from within Clojure, proxy is recommended over gen-class.
10:34	Belaf	clgv: I somehow measured it, actually:
10:34	Belaf	user> (time (dotimes [n 1000000] (gdtest.core/filter0 0 0 0)))
10:34	Belaf	"Elapsed time: 30.198033 msecs"
10:36	hyperboreean	raek: thanks
10:36	Belaf	cemerick: I think I couldn't use proxy, as I needed to access the protected canFilterIndexColorModel member in RGBImageFilter and proxy doesn't seem to allow it.
10:37	cemerick	Belaf: True enough. nm then :-)
10:39	Belaf	the sad point is that the filter works by calling a method once for each image pixel, so for big pictures it slows down a lot...
10:41	cemerick	Belaf: If there is any reflection going on, compiling with warn-on-reflection bound to true will emit useful warnings.
10:41	clgv	Belaf: you should measure inner and outer time to see if type hints might be really the reason
10:41	Belaf	cemerick: allright, I'm going to try that, thanks.
10:42	Belaf	clgv: sorry, what do you mean by inner and outer time?
10:43	clgv	Belaf: you just measured the outer time. the inner one is within the function.
10:45	Belaf	clgv: do you have any suggestion on how to measure it? the code inside is really basic, actually:
10:45	Belaf	(defn -filter1
10:45	Belaf	[this x y rgb]
10:46	hv	Is there a Trie class (hopefully with collection inteface) in clojure?
10:46	clgv	Belaf: you tried the warn-on-reflection hint already? I'd do that before
10:47	Belaf	cemerick: is this what you were suggesting "(binding [warn-on-reflection true] (compile 'gdtest.aux))" I got no warnings from it.
10:47	clgv	Belaf: do (set! warn-on-reflection true) after your ns-statement
10:49	Belaf	clgv: I had some warnings, actually:
10:49	Belaf	Reflection warning, gdtest/aux.clj:24 - call to setCanFilterIndexColorModel can't be resolved.
10:49	Belaf	Reflection warning, gdtest/aux.clj:30 - reference to field filter can't be resolved.
10:49	clgv	time to fix them with type hints ;)
10:50	Belaf	Allright, going to try it... Thanks for your support!
10:55	fliebel	hv: http://stackoverflow.com/questions/1452680/clojure-how-to-generate-a-trie
10:55	fliebel	Smart use of assoc-in :)
11:44	Belaf	Just in case it might be useful to somebody else: fixing the reflection warnings did the trick, now the (trivial) filter is 15 times faster. The only needed thing was to add a type hint to the class being defined to the 'this' parameter of method definitions.
11:44	Belaf	Thanks so much for your help.
11:44	manutter	Thanks for the report :)
11:45	manutter	I'll have to add "reflection warnings" to the list of terms I mindlessly parrot whenever I hear about performance issues.
11:46	Belaf	Well, it seems a good tool to know.
11:47	clgv	but dont forget to comment them before compiling a jar ;)
11:47	manutter	I'd heard of it before, but was kind of hazy on the details
11:47	clgv	warn-on-reflection, I mean ;)
11:47	manutter	indeed
11:48	Belaf	I might try it, but... what would the result be?
11:49	Belaf	oh, I think I know what you mean... I compiled one of my other files with it ... :-)
11:49	clgv	a compiler error
11:50	clgv	or wait. I think I get it when trying to run the jar
11:50	clgv	had it with print-length and print-level so I just used (binding [print-length 10, print-level 9] ...) in my main method
11:51	Belaf	compiling another of my files I got a number of such warnings, but I think I'm not going to add type hints for all of them, unless they are slowing things down... I like so much using things without knowing too much what they are... ;-)
11:52	clgv	seems you do a lot interop then ;)
11:52	manutter	what would be useful would be some kind of mechanism that would let you conditionally compile code based on whether you were executing lein repl or lein jar
11:54	zippy314	Hi folks, I'm trying to write a macro or function that defines a function in a particular namespace (by calling ns) and then then switches back to the current namespace, but this: (defn x [] (ns fish) (defn y [] 1) (ns user)) doesn't seem to work. Is this possible?
11:55	zippy314	What I'm trying to do is to put functions into namespaces on the fly.
11:57	clgv	zippy314: binding ns to the namespace could work
11:58	technomancy	manutter: there's a :repl-init-script setting you could use
11:59	manutter	I was looking at that, hmmm
11:59	manutter	Just brainstorming, though, don't have an immediate use for it
12:00	manutter	we were just talking about (set! warn-on-reflection true) and the need not to compile that into the final jar.
12:00	technomancy	(when (System/getenv "LEIN_VERSION") (set! warn-on-reflection true))
12:01	manutter	aha, nice :)
12:08	zippy314	cigv: how do you do that?
12:39	zippy314	Is there an opposite to refer? I.e. if you used (refer 'some-ns) and now you want to do something like (unrefer 'some-ns)
12:41	semperos	zippy314: :exclude can be used on individual fn's within a namespace
12:42	zippy314	hmm. It looks like ns-unmap actually does what I want.
12:43	zippy314	But it looks like if you use refer and that overwrites a reference you can't get the old one back easily.
12:43	semperos	you can provide aliases and rename fn's using the ns macro, so if you see that you have a conflict, there are several ways to mitigate it
12:51	raek	zippy314: to get the old one: ns-unmap and then refer
12:52	raek	or refer to it with it's fully qualified name
12:52	zippy314	I'm doing this because I'm defining functions on the fly and I want them to go into their own namespaces, so it gets kind of hairy...
12:54	raek	zippy314: maybe you could let them have a certain prefix (assuming they can have arbitrary names which might not "respect" clojure names)
12:55	zippy314	hmm that might work for starters...
12:56	amalloy	it seems to me like you're a zillion times better off not trying to define top-level functions at runtime in the first place. why do you feel you need to do this?
12:56	raek	or if their usage is determined "on the fly" too (i.e. you don't have hand-written code that uses the names), put them in one map
12:57	raek	using a namespace as a map is not as ideomatic in Clojure as corresponding practices are in Ruby and Python
13:00	raek	it's ok to have functions outside vars :)
13:02	manutter	,(let [foo (fn [] (println "foo")), bar (fn [] (println "bar")), fly {:foo foo, :bar bar}] ((fly :foo)))
13:02	clojurebot	foo
13:02	dnolen	zippy314: what about your application requires these functions needs to be defined at runtime?
13:05	zippy314	What I'm writing is a system in which you can define grammars and semantics for those grammars as the running system. So for example I'd like to be able to do things like have lexically scoped grammatical constructs, just as we are used to lexically scoped variables.
13:06	zippy314	In other words I'd like to define a grammar which includes positions of things, plus functions, and have them appear to be usable lexically, as opposed to in the context of an entire file.
13:06	dnolen	zippy314: then why not local functions?
13:07	zippy314	like how?
13:07	dnolen	,(let [f (fn [a b] (+ a b))] (f 1 2))
13:07	clojurebot	3
13:08	zippy314	hmm. That might work...
13:08	semperos	things like what clj-record does make sense for creating top-level fn's at runtime
13:09	semperos	but if you just need scoping, local fn's are probably a better bet
13:09	zippy314	I've read a little about clj-record, I need to dig into the source for that.
13:09	semperos	well, not at runtime perse, but dynamically
13:10	semperos	it's init-model macro dynamically generates CRUD fn's for a given database table
13:10	semperos	so that they're available elsewhere for CRUDdy activities
13:10	zippy314	But, the issue with local functions is that you can only use them once, wouldn't you have to re-declare them every time? The idea is to define the grammar for such functions, and then be able to use that grammar, lexically scoped.
13:11	semperos	zippy314: you might need to provide actual/pseudo code examples to get across exactly what you want
13:11	raek	zippy314: are you making a macro that will run once during initialization or an interpreter that will do this at run-time?
13:11	zippy314	the latter.
13:12	raek	then you should definitely not use defs for this
13:12	KirinDave	zippy314: If only we could pass functions around in a map :)
13:12	KirinDave	If only we could have... functions... without names. :)
13:12	zippy314	although the former might work too.
13:12	zippy314	:-)
13:13	raek	if you will never write any source code that refers to the generated functions, there is no need for defs
13:14	raek	defs are for programmers :)
13:38	ejackson	dnolen: what kind of American are you - that's FRENCH !
13:39	dnolen	heh, I suppose I lack that level of nationalism.
13:39	manutter	Eh oui? Et qu'est-ce qu'ils ont, les francais? Hmm?
13:39	manutter	:)
13:39	ejackson	:)
13:42	fliebel	dnolen: What is the relation between OCaml and Go?
13:42	dnolen	fliebel: high performance systems programming languages w/ high-level features.
13:43	fliebel	dnolen: Oh, maybe I should check that out, I heard they have good pattern matching ;)
13:44	dnolen	fliebel: ;)
13:46	fliebel	dnolen: I have read some of the big paper by now, still not making much sense. I get the general idea, but when they start to bend equals signs ( ⊇ ), I get lost.
13:47	dnolen	fliebel: don't be confused, just means subset
13:47	fliebel	Wow, awesome, my unicode pallet has names for these things that make sense
13:48	fliebel	Maybe I should read it again with the pallet at hand :)
13:50	dnolen	fliebel: you should, the math stuff is really about defining some things tersely. The only part that doesn't make sense to me is the operational semantics (?) notation. But that's not important to understand the paper anyhow.
13:52	fliebel	ah-ha!
13:56	dnolen	fliebel: it also turns out that using if + instance? checks is probably going to much faster for most predicate dispatch use cases. They put us in the 90ms territory versus 2000ms for multimethods.
13:58	dnolen	i.e. when looking at 1e8 iterations on a 3 test dispatch.
13:58	subnetmax	hello - is there an elegant way to create a sequence with each item based on a function of all the previous items?
13:58	subnetmax	lazily would be nice
13:59	fliebel	subnetmax: iterate, kind of...
13:59	amalloy	subnetmax: reductions
14:00	amalloy	&(reductions + (range 5))
14:00	sexpbot	⟹ (0 1 3 6 10)
14:01	fliebel	dnolen: Wait, what are multimethods using internally? And are we talking a flat if, or some hand crafted DAG?
14:01	subnetmax	sorry, not able to get my head around how to use that.... i have a function next-item that takes a list of all previous items, could you show me how to use iterate or reductions to do that?
14:02	amalloy	subnetmax: all previous elements that you've output?
14:02	subnetmax	yeah
14:02	fliebel	(iterate #(conj % (next-item %)) the-items)
14:03	amalloy	fliebel: yeah, looks good
14:03	subnetmax	and the-items is [] for the first call of this?
14:03	amalloy	subnetmax: it depends what your input is
14:04	amalloy	that is: imagine this function already existed. how would you call it?
14:04	subnetmax	i should say that i'm using rand to help generate each item, so my function is not referentially transparent
14:05	fliebel	subnetmax: well, the-items could be [], so then it'd invoke next-item with [] and conj that onto the empty vector.
14:05	subnetmax	ok, i'll see if i can make that work, thanks very much
14:05	amalloy	this all sounds too much like unfold
14:06	subnetmax	well everything sounds like some kind of fold if you think about it enough :)
14:06	fliebel	&(take 10 (iterate #(conj % (reduce + %)) [1]))
14:06	sexpbot	⟹ ([1] [1 1] [1 1 2] [1 1 2 4] [1 1 2 4 8] [1 1 2 4 8 16] [1 1 2 4 8 16 32] [1 1 2 4 8 16 32 64] [1 1 2 4 8 16 32 64 128] [1 1 2 4 8 16 32 64 128 256])
14:06	fliebel	sweeet :)
14:06	fliebel	amalloy: Time to mention amalloy-utils :)
14:07	amalloy	fliebel: why would i, when you're here to do it for me
14:07	fliebel	amalloy: Because I don;t know where unfold lives :O
14:07	amalloy	aww
14:07	amalloy	it's in seq
14:07	amalloy	https://github.com/amalloy/amalloy-utils/blob/master/src/amalloy/utils/seq.clj#L48
14:09	fliebel	amalloy: How would you solve this problem using unfold?
14:09	amalloy	note that if you actually depend on all the previous outputs, you can never generate an infinite sequence - you'll be holding onto the head of a large sequence forever
14:10	amalloy	fliebel: i wouldn't, really, because unfold assumes you want to generate an infinite sequence
14:10	subnetmax	i'm only looking to generate max 30 items, and performance does not matter
14:10	fliebel	amalloy: You can never generate infinite sequences in a finite universe :)
14:10	amalloy	and the assumption that element x really depends on all previous elements is anathema to me
14:11	fliebel	subnetmax: What are you doing with all those ellements?
14:12	subnetmax	well for example, picking people for tasks, you need to know who has already been picked, along with other considerations
14:13	manutter	subnetmax: for that you could just generate a list of people, shuffle it, and pick them off in order
14:13	manutter	(which will be a random order after the shuffle)
14:14	subnetmax	imagine that as you pick each person, you need to look at who has already been picked to avoid personality clashes
14:14	subnetmax	but the issue is not important enough to start looking a large constraints solver
14:14	manutter	ah, ok
14:14	amalloy	subnetmax: don't generate a sequence of persons, imo
14:14	fliebel	subnetmax: Oh, I was just about to mention Logos.
14:14	amalloy	reduce from a sequence of tasks into a map of assignments
14:14	amalloy	then you only depend on the one object: a map
14:15	subnetmax	why is depending on a map better than depending on a list
14:15	amalloy	it's not, really
14:15	amalloy	but it's much easier to work with
14:17	fliebel	subnetmax: Have a look at the readme of core.logic, especially disequallity and defining facts. https://github.com/clojure/core.logic
14:26	dnolen	fliebel: multimethods use a couple of things, memoization, PersistentHashMap of dispatch values
14:27	dnolen	fliebel: DAG -> if. but I want it to be flexible enough to goto case if we see that that'll be more efficient. shared parts of the tree are lifted into fns, like matchure.
14:28	dnolen	fliebel: the coolest thing about the paper is the notion of necessity from lazy evaluation - that's what makes the smaller trees possible.
14:29	subnetmax	i can solve my problem like this http://pastebin.com/083aRBUe - i was just thinking that i seem to be doing something that other people do and so perhaps there is already a function for
14:32	fliebel	subnetmax: Well, iterate and unfold would work.
14:33	amalloy	iterate or unfold, i think is clearer
14:35	fliebel	dnolen: Okay, I did not understand that necessity part at all.
14:41	no_mind	If I define a record with two attributes lets say first_name and last_name. Can I define a protocol which will change the attributes of the record ?
14:41	fliebel	dnolen: The raging hordes are starting to respond to your question :)
14:42	fliebel	no_mind: records are immutable
14:42	fliebel	But you can say (assoc this :first_name "foo" :last_name "bar")
14:53	subnetmax	Is it right that (disj #{1 2 3} #{2}) evaluates to #{1 2 3}? I was expecting #{1 3}
14:56	manutter	,(doc disj)
14:56	clojurebot	"([set] [set key] [set key & ks]); disj[oin]. Returns a new set of the same (hashed/sorted) type, that does not contain key(s)."
14:57	manutter	hmm
14:57	manutter	,(disj #{1 2 3} #{2})
14:57	clojurebot	#{1 2 3}
14:57	subnetmax	user=> (disj #{1 2 3} #{2})
14:57	subnetmax	#{1 2 3}
14:58	manutter	,(disj #{1 2 3} 2)
14:58	clojurebot	#{1 3}
14:58	manutter	,(disj #{1 #{2} 3})
14:58	clojurebot	#{1 #{2} 3}
14:58	manutter	doh
14:59	manutter	ok, got it
14:59	manutter	,(= #{2} #{2})
14:59	clojurebot	true
14:59	manutter	well, got most of it
15:00	subnetmax	sorry, what am i doing wrong?
15:00	manutter	#{2} != 2
15:01	subnetmax	oh i see, it's not two sets, it a set and a list of keys to remove
15:01	manutter	#{2} is not one of the values in #{1 2 3}
15:01	manutter	yeah
15:01	subnetmax	how can i do a disjunction between two sets?
15:02	dnolen	fliebel: heh, not getting much upvotes, but noone responding w/ an interesting answer either. Except "easier" maybe.
15:03	manutter	,(remove #{2} #{1 2 3})
15:03	clojurebot	(1 3)
15:03	manutter	hrm, close
15:04	manutter	,(into #{} (remove #{2} #{1 2 3}))
15:04	clojurebot	#{1 3}
15:04	manutter	,(into #{} (remove #{1 4} #{1 2 3 4 5}))
15:04	clojurebot	#{2 3 5}
15:04	fliebel	dnolen: How do you know? (not= minutes upvotes) I wonder if anyone there knows both OCaml and Go ( and Rust?)
15:05	raek	subnetmax: check out the functions in clojure.set
15:05	manutter	subnetmax: "into #{}" plus "remove" seems to work
15:06	bartj	subnetmax, disjunction = union of two sets ?
15:06	manutter	I'd have thought there'd be a built-in for that, but...
15:06	bartj	there is
15:06	fliebel	manutter: there is, raek said it.
15:06	bartj	check out clojure.set
15:06	manutter	,(disj #{1 2 3 4 5} (seq #{2 4}))
15:06	clojurebot	#{1 2 3 4 5}
15:06	subnetmax	ah, difference
15:07	manutter	sigh
15:07	raek	,(clojure.set/difference #{1 2 3 4 5} #{2 4})
15:07	clojurebot	#{1 3 5}
15:07	manutter	I thought that one might have worked
15:07	subnetmax	it's just that difference and disjunction have exactly the same meaning, so why would i look for difference when i had found disj?
15:07	dnolen	fliebel: it doesn't look like it. But honest opinion if you know OCaml you'll think is a bad joke.
15:07	dnolen	think Go
15:07	manutter	Oh, there it is, I was looking in clojure-contrib.set
15:08	raek	subnetmax: disjunction means "or", so that means the set of the elements that are in set a or set b
15:08	raek	(inclusive or)
15:08	raek	disj stands for disjoin
15:08	raek	which means to separate
15:09	fliebel	dnolen: I'd say one needs some brains to write a language, so someone must have thought Go was a good idea. One of those people even said Rust was written in OCaml.
15:10	raek	hrm. but "disjoin" and "disjunction" do share a common root. I guess the meaning of "disjunction" has shifted in meaning over the history
15:15	dnolen	fliebel: Go is a classic example of Worse Is Better. That maybe a good or bad thing depending on your perspective.
15:39	dnolen	fliebel: re: necessity. it's just about figuring which column must be tested. if it's going to be tested in every path, test it first, turns out this can usually produce smaller trees.
15:41	fliebel	dnolen: But how do you ever figure that out? I mean, okay, when you write (and (< x 3) (< x 4)) you could maybe figure out that the first one is redundant, how can you know?
15:41	fliebel	Is this why the wiki said you had to define predicates and their relations?
15:42	dnolen	fliebel: logic programming remember.
15:42	dnolen	fliebel: exactly, those kinds of issues are checked before we produce the dag.
15:43	fliebel	Subclassing and negation is the easiest to check probably.
15:45	bartj	what does ~ and ` mean while writing macros ?
15:45	bartj	*do
15:46	fliebel	&(let [x 5] `(+ 1 ~x))
15:46	sexpbot	⟹ (clojure.core/+ 1 5)
15:47	bartj	oh, I was reading ` as a '
15:48	raek	bartj: syntax-quote ` is very similar to quote ' except that it resolves symbols and has a unquote feature
15:49	dnolen	fliebel: yeah the key bit is that you can't use just anything for a guard. You have declare the predicates you will use as guards, then we can reason about them.
15:53	bartj	,(doc `)
15:53	clojurebot	Unmatched delimiter: )
15:53	fliebel	dnolen: So in the end you have kind of a trie of guards instead of words :)
15:54	raek	bartj: it's documented here http://clojure.org/reader
16:26	bartj	raek, thank you, as usual
16:45	lawrent	Does clojure support currying? If not, do you often find that you miss this feature?
16:46	opqdonut_	,(doc partial)
16:46	clojurebot	"([f arg1] [f arg1 arg2] [f arg1 arg2 arg3] [f arg1 arg2 arg3 & more]); Takes a function f and fewer than the normal arguments to f, and returns a fn that takes a variable number of additional args. When called, the returned function calls f with args + additional args."
16:46	lawrent	That's a little clumsy, no?
16:46	opqdonut_	not really, no
16:46	lawrent	Seems to me that currying is one of the very basics of functional programming, along with referential transparency, and clojure does neither well
16:46	opqdonut_	I miss a real type system more than currying
16:47	opqdonut_	and clojure does referential transparency better than any other lisp
16:47	opqdonut_	or any other jvm language for that matter
16:47	lawrent	...but not better than haskell
16:47	kephale	partial can be limiting due to ordering of arguments
16:47	lawrent	exactly!
16:47	opqdonut_	well so is ordinary currying
16:48	amalloy	kephale: define flip, then partial a flipped version
16:48	kephale	but you can get the same effect with the #( blah %1 %2 ) macro
16:48	opqdonut_	but yeah, there's no equivalent of flip/rcurry in the clojure standard lib
16:48	kephale	amalloy: i tend to just use the function reader macro
16:48	amalloy	so do i
16:49	amalloy	but it's not hard to get partial to fill in something other than the first N arguments
16:49	kephale	noted
16:49	amalloy	i have a reodering library for juggling around function arguments in various ways if you need something more sophisticated than flip
16:50	dnolen	lawrent: given fns can have variable arity how do you see currying as useful in Clojure?
16:51	dnolen	lawrent: a pure function in Clojure is just as referentially transparent as in any other lang, FP or not.
18:02	zippy314	how come (defn x.x [] 1) works, but you can't call (x.x)?
18:02	zippy314	heh
18:02	zippy314	(defn y.y [] 1)
18:03	hiredman	the code that resollves symbols to vars/classes assumes a symbol with a dot in it is a class
18:07	zippy314	hiredman: thanks. another q: why can't I do something like this: (def x "foo") (defn (symbol x) [] "bar")
18:09	amalloy	because (symbol x) isn't a symbol, it's a list
18:09	amalloy	defn needs a literal symbol
18:09	amalloy	&`(defn ~(symbol "test") [] "data")
18:09	sexpbot	⟹ (clojure.core/defn test [] "data")
18:09	hiredman	zippy314: the defn special form doesn't evaluate the first arg
18:10	hiredman	or any of it's args
18:13	amalloy	hey hiredman, does clojurebot have a trigger to make him process commands or eval forms mid-message? something like, "hey zippy314, check out ~~source defn"?
18:15	hiredman	no
18:21	semperos	writing a Clojure api around a Java lib; what do folks thing would be a good name for a namespace that only has defmethod's of print-method to make printing the Java original objects more meaningful?
18:26	amalloy	myapp.tostring?
18:27	lawfulfalafel	could someone recommend a good tutorial for making your first project with lein?
18:27	lawfulfalafel	I am having a bit of trouble finding an explicit and up to date version
18:27	technomancy	lawfulfalafel: have you read through "lein help tutorial"?
18:28	lawfulfalafel	oh sweet, your the author right?
18:28	amalloy	https://github.com/technomancy/leiningen/blob/master/TUTORIAL.md
18:28	technomancy	aye
18:29	amalloy	looks like our good friend technomancy updated that yesterday. hard to get more canonical and current than that
18:29	lawfulfalafel	oh that looks really useful, I was stuck on the initial github page and didn't see it
18:29	technomancy	these days it's bundled with lein under the help task
18:33	brehaut	has anyone using clojure.contrib.sql or clojureql encounted "Generated keys not requested. You need to specify Statement.RETURN_GENERATED_KEYS to Statement.executeUpdate() or Connection.prepareStatement()."
18:36	hiredman	brehaut: yes
18:37	brehaut	hiredman: any suggestions on how i might fix it?
18:37	hiredman	it is a problem with c.c.jdbc
18:37	hiredman	we ended up writing our own thinner wrapper over jdbc
18:37	hiredman	that we use in conjuction with c.c.jdbc
18:37	hiredman	just some convience stuff around raw jdbc statements
18:38	hiredman	(not available anywhere, btw)
18:38	brehaut	ok, thanks
18:38	ataggart	Since the new clojure.java.jdbc is being worked on currently, it's a good time to give feedback.
18:38	scgilardi	https://github.com/clojure/java.jdbc also has some code that may be helpful.
18:39	hiredman	I think the new one already defaults to asking for generated keys to be returned, but I don't recall for sure
18:39	technomancy	the dude himself returns
18:40	brehaut	huh the most curious thing is that this same project works fine running locally connected to the live database via ssh tunnel
18:43	clizzin	any best practices for dealing with date/time in clojure? is there a wrapper for that hideous beast, the java calendar?
18:43	seancorfield	hiredman: brehaut scgilardi yes, c.j.j will return generated keys by default for any single insert operation
18:43	brehaut	seancorfield: cool
18:44	technomancy	clizzin: avoid j.u.Calendar and Date at any cost; you want clj-time
18:44	seancorfield	there will be a 0.0.1 release this weekend (snapshots exist right now)
18:44	brehaut	seancorfield: is that going to be backward compat with 1.2.x?
18:44	clizzin	technomany: ah yes, i remember using that once but had forgotten all about it. thanks!
18:45	seancorfield	brehaut: should be - all the new behavior is optional (naming strategies etc)
18:45	brehaut	seancorfield: thats great, thanks :)
18:45	seancorfield	oh, exceptions are no longer printed to err - but the print-* functions are exposed so you can leverage them
18:45	seancorfield	otherwise it should be just the same by default...
18:46	seancorfield	and it has its own resultset-seq so you'll be able to control how sql entity names are converted to keywords (and vice versa)
18:46	seancorfield	i'd love to get some folks using it (apart from me!) so i can get more feedback :)
18:47	zrilak	Just saw a Clojure snippet to lazy-generate a Fibonacci sequence: (def fib (lazy-cat [0 1] (map + fib (rest fib)))) , and happened upon something superficially very similar in the SICP chapter on stream processing. Is that some kind of well-known "pattern" (for want of a better word) in functional programming? :)
18:49	brehaut	zrilak: its (probably) not something you would want to do in clojure because the program will hold onto the head of the fib sequence
18:49	brehaut	zrilak: meaning that as you realize more and more of it you will permenantly consume your heap
18:50	zrilak	I understood it will generate an embedded concatenation of [0 1] [1 [2 [3 [5... ]
18:50	zrilak	gotcha, yes, I thought so myself
18:51	brehaut	zrilak: the pattern is well known; you see that sort of thing more in haskell though
18:51	zrilak	all right!
18:52	zrilak	brehaut: that's good to know, since a good part of recognizing a piece of code lies in having been exposed to isomorphic examples
18:52	zrilak	isomorphous*
18:56	joshua__	Where can I find a project.clj file which uses clojure-contrib 1.3? I'm trying to use 1.3 priority map, but lein deps is giving me errors.
18:56	VT_entity	christ are we already on 1.3?
18:56	joshua__	It is alpha etc.. but I need a priority queue and priority map works for that.
18:57	VT_entity	I dunno if I can help you... out of curiosity... what changed in 1.3?
18:58	technomancy	joshua__: I don't think there's a monolithic contrib that works with 1.3
18:58	joshua__	technomancy, I just want clojure-contrib/priority-map
18:59	technomancy	if there's no AOT in it you may be able to use 1.2
18:59	joshua__	technomancy, alright. Thanks.
19:00	joshua__	VT_entity, https://github.com/clojure/clojure/blob/master/changes.txt shows some changes. The most interesting changes I've read about is the change to contrib. It is being set up so you can choose to include only the libraries you want.
19:00	VT_entity	thank you
19:06	clizzin	if i run a shell command from clojure (using java's Runtime.exec), does anyone know if that starts a separate process, or is it contained within the same java process?
19:07	technomancy	it's a separate process, with caveats
19:08	technomancy	there's a bug in the JVM where the second process temporarily requires as much memory as the parent process
19:08	technomancy	which makes it usually fail in production
19:09	clizzin	technomancy: i see. hmmm
19:12	clizzin	if i'm exec-ing several processes simultaneously using future, does each new process require the cumulative memory amount of all the previously exec-'d processes?
19:12	Derander	anyone have any experience inserting piles of data w/ congomongo? I keep getting "db message size is too big (some number) max is (some slightly smaller number)"
19:13	clizzin	(basically, i have a ruby script that does some shell commands, and i thought i'd try to take advantage of clojure's concurrency to run some of those shell commands concurrently since they don't always depend on one another.)
19:13	Derander	https://gist.github.com/958174 <-- this is the clojure code that I'm running. it's trying to insert a collection of hashes.
19:16	technomancy	clizzin: not cumulative, no. each subprocess will just take as much memory as the parent
19:16	technomancy	for it to work reliably you need the ruby process to be launched independently and communicate with it over a socket or rest or something
19:17	technomancy	unless you know your JVM will never be using more than 50% of the system's available memory
19:19	clizzin	technomancy: oh, the idea is to replace the ruby script with the clojure program. this sounds potentially dangerous though, since each of the shell commands i'm running is a hadoop job (a small hadoop job, but still, potentially bad)
19:20	technomancy	who's doing the launching?
19:21	clizzin	clojure is launching the jobs
19:21	clizzin	the goal is to cut ruby out entirely
19:22	technomancy	isn't the point of hadoop to run jobs on a remote cluster?
19:24	seancorfield	joshua__: this monolithic contrib exists for 1.3.0 http://build.clojure.org/releases/org/clojure/contrib/standalone/1.3.0-alpha4/
19:25	seancorfield	i recall it being a bit fussy due to some additional settings in leiningen
19:25	clizzin	yes. basically, there are a series of hadoop jobs i need to run, and i invoke them by calling 'hadoop jar job.jar class-name args' on the shell. but i want to run several of these jobs regularly, so i was hoping to automate that. i did it initially using ruby, but thought it might be easier to run several commands at once using clojure
19:25	seancorfield	if you want to try, i can look in git history of project.clj to see how i used to have it setup back then
19:25	clizzin	there is probably a better way to do this though -- any ideas?
19:26	jnberg	bash script + cron! :D
19:26	clizzin	jnberg: can that kick off asynchronous commands?
19:26	jnberg	thought you were just looking to queue up jobs for hadoop
19:27	clizzin	yeah. but when i run 'hadoop jar ...', the shell blocks until the job is done, no?
19:27	seancorfield	joshua__: here's what i had in project.clj for alpha2: [org.clojure.contrib/standalone "1.3.0-alpha2"]
19:28	jnberg	hmm, not sure with hadoop honestly, sorry :( With gridengine it doesn't block, but that doesn't help :-/
19:30	clizzin	oh wait, duh, i can run the command with '&' at the end
19:32	clizzin	oh, well, ruby doesn't run that in background, but there's another easy way to do it. anyway, i'll stop talking about non-clojure stuff now.
20:30	zippy314	&(+ 1 1)
20:30	sexpbot	⟹ 2
23:43	symbole	What's the recommended way of making a Clojure application aware of the environment that it's running in, and subsequently load the correct config file (properties equivalent in the Java world)?
23:43	hiredman	there is System/env
23:45	symbole	I was thinking of passing -Denv=foo, and loading foo's config file. Is this idomatic, or are multiple approaches used?
23:45	symbole	Loading foo's config file by looking at System properties, I meant.
23:52	symbole	I gess Clojureland is at sleep. I'll come back later.