#clojure – 2009-02-28

2009-02-28

00:10	durka42	what does "the oft-requested letrec" do?
00:13	ayrnieu	durka42 - all the bindings established by let are visible within their definitions.
00:14	durka42	so you can let things like fibs?
00:14	ayrnieu	well, that isn't a very interesting case, because it's only one binding.
00:15	ayrnieu	(letrec [even? #(if (zerop %) true (not (odd? (1- %)))) odd? #(if (zerop %) false (not (even? (1- %))))] (even? n))
00:17	durka42	so all the bindings have to be forward declared or some such magic?
00:18	ayrnieu	letrec isn't a function; it isn't that the definition of even? is evaluated and then the definition of odd? is. The magic is just the usual business of deciding when bindings are made and what they're visible to.
00:20	ayrnieu	CL has a LET that doesn't expose its bindings until after they're mind, and a LET* that exposes them sequentially. So (let ((a b) (b a)) ...) renames a B and A defined outside this let, whereas the LET* variant would give you two names for outer-b
00:23	ayrnieu	so does clojure have letrec now, or is it still oft-requested?
00:24	durka42	rhickey added an issue
00:24	durka42	i take it is not a synonym to the scheme letrec
00:25	ayrnieu	why do you take that?
00:28	durka42	i thought scheme letrec named the let so you could refer to it from within itself
00:29	durka42	e
00:29	ayrnieu	scheme's letrec is as I described. The EVEN?/ODD? example comes from t-y-s-i-f-d.
00:29	ayrnieu	teach yourself scheme in fixnum days.
00:30	ayrnieu	scheme also has named lets, but clojure has these already.
00:30	ayrnieu	durka - you might implement letrec in clojure as an exercise. At least at a toplevel macro, it should be very easy.
00:33	danlarkin	why wouldn't clojure's let just gain letrec functionality instead of gaining letrec? Is it that much less efficient?
00:34	msingh	hello is there any example code to look at that uses java sound? i'm interested in writing a small multiplatform audio comm app for voicing because there is nothing that i've tried works on linux
00:34	ayrnieu	danlarkin - it is different functionality.
00:35	danlarkin	ayrnieu: oh, it breaks something that normal let gives you?
00:36	ayrnieu	,(let [a 1 a (inc a) a (inc a)] a)
00:36	clojurebot	3
00:36	danlarkin	I thought it just added more functionality: the ability to have recursive definitions
00:36	durka42	does this page apply? http://neilmitchell.blogspot.com/2007/03/let-vs-letrec.html
00:36	durka42	The rule is that in a letrec you introduce the names you are defining before computing their values (so the x = x refers to itself), but with let you only introduce the names once you get to in (so the x = 1 is still in scope).
00:38	danlarkin	I guess my understanding of letrec was a little off
00:38	ayrnieu	,(let [a 1] (let [b (inc a) a 1] [b a]))
00:38	clojurebot	[2 1]
00:39	ayrnieu	both of these examples would be different in with letrec.
00:40	ayrnieu	rhickey could decide that clojure's `let bind the way letrec does (the way he's already decided that it bind in the way of CL's LET* instead of its LET), but this is not a simple move 'upward'.
00:41	durka42	sorry, how would that last example be different? (inc a) would apply to the second a, which is still 1
00:42	ayrnieu	it's a shifting around of hassles. I think it's not unreasonable to say that letrec's hassles are more bearable in clojure that its present hassles. But if he does decide to do this, he should decide pretty quickly. It's a breaking change that hard to look for.
00:42	ayrnieu	sure, the second a should be something else.
00:43	ayrnieu	,(let [a 1] (let [b (inc a) a :parrot] [b a]))
00:43	clojurebot	[2 :parrot]
00:43	durka42	if the inner let was letrec, ClassCastException
00:45	ayrnieu	anyway, you can write letrec in clojure, definitely as a top-level macro. Have (let [even? #(...) odd? #(...)] (defn integer-filter [...] ... even? ... odd?)) resolve to (do (forward-declaration odd?) (defn GENSYM_even? ...) ... (let [even? GENSYM_even? odd? GENSYM_odd?] ...))
00:53	banisterfiend	hey guys anyone know a tutorial that 'll tell me how to get clojure up and running on a debian linux system?
00:54	ayrnieu	banister - clojure.org -> wiki -> getting started.
00:54	durka42	~pl
00:54	clojurebot	have you heard about the bird? is<reply>The bird, bird, bird, the bird is the word.
00:54	durka42	~transform
00:54	clojurebot	It's greek to me.
00:55	durka42	clojurebot: transform is http://github.com/hiredman/odds-and-ends/blob/8a84e6ddbad9d71f714ba16c3e1239633228a7eb/functional.clj
00:55	clojurebot	Alles klar
02:01	bradbev	I'm trying to use files in my project, like (ns memorytool.unit-tests (:refer memorytool.simheap)), and I want to do (simheap/foo 1 2). I can't figure out how to use :as.
02:03	Chouser	(:use [memorytool.simheap :as simheap :only ()])
02:03	Chouser	or more conventionally, (:require [memorytool.simheap :as simheap])
02:04	bradbev	ah, thanks very much. That's the only thing I miss about Clojure's documentation - small examples of common usage
02:04	durka42	~api examples
02:04	clojurebot	examples is http://en.wikibooks.org/wiki/Clojure_Programming/Examples/API_Examples
02:04	Chouser	yeah.
02:04	durka42	(not complete)
02:05	Chouser	also, contrib
02:05	bradbev	ah, that's cool - I didn't know about that
08:30	blbrown	rhickey, how do you feel about strong static typed languages like haskell or scala. They offer completely different styles from clojure/lisp. Are there places to use one style or the other
08:31	blbrown	...question directed to anyone else that is up, also
08:31	Chousuke	I like haskell's system.
08:31	blbrown	and ideally with haskell's type inference, you don't have to necessarily set the type for each function, etc
08:32	Chousuke	I think type inference is necessary for static typing not to be a nuisance :P
08:32	blbrown	yea
08:33	blbrown	Chousuke, are there are apps where you might use haskell and then apps where you might use haskell. Actually I could see myself using scala for a server project I want to write
08:34	blbrown	scala is being used at Twitter, but I don't have all of the details
08:35	Chousuke	hmmh
08:35	Chousuke	It's difficult to say outright when static typing is better than dynamic typing.
08:36	blbrown	or vice versa
08:36	Chousuke	yeah.
08:37	bOR_	(apply concat \A 1 "a")
08:37	bOR_	?
08:37	bOR_	wonder what you can't do statically that you can do dynamically.
08:37	blbrown	Chousuke: this is just my own subjective opinion, but clojure is certainly going to be a lot lighter and easier to work with. I am using clojure for GUIs and web development. I could see where scala/haskell could be used more for backend/server development
08:38	blbrown	I hear a lot, that lisps are good at bottom up programming
08:38	rhickey	blbrown: the whole trick with type systems is expressivity - do they let you do what you want? Are the benefits they provide worth the complexity, time and effort? Do they introduce rigidity into the system as a whole? I'm not opposed, and think Haskell is fascinating
08:38	Chousuke	With dynamic typing it's easy to misuse a function. in Haskell at least the type system ensures that functions are used where they make sense.
08:38	Chousuke	and nonsensical stuff is caught before runtime
08:39	Chousuke	on the other hand, overriding the type system when it's wrong about something is not as easy.
08:40	blbrown	Chousuke, it also gives you a bit of flexibility
08:40	bOR_	much still to learn in the computer science department for me :).
08:41	blbrown	whateve the case, architecture wise, there is no reason why you can't built a multi-language app. Clojure and Haskell. Clojure and Scala. Clojure and Java
08:41	blbrown	...based careful analysis and a need to do so, of course
08:43	Chousuke	You said you use Clojure for GUIs and web development; I think dynamic typing fits interactive programs well.
08:44	blbrown	exactly
08:44	Chousuke	you might have many input sources and callbacks and whatnot, and dynamic typing allows for a simpler interface because you don't have to worry about typing.
08:45	blbrown	clojure is the new smalltalk, hehe
08:47	rhickey	E.g., what is the 'type' of Clojure code-as-data? All those nested heterogeneous collections etc. It's not hard to understand, but difficult to express using types (at least without abandoning them to a universal unifying type)
08:50	bOR_	taking a break from writing, and reading up on wikipedia / type system to catch a bit of the background :).
08:50	blbrown	hmm, so the coding style associated with clojure doesn't really lend itself to having to define the types, which is fine.
08:53	Lau_of_DK	Guys - Im having a little trouble incorporating jMEPhysics 2 with jME 2.0 - Any one here who's got any experienco ?
09:04	Chouser	blbrown: I don't know that clojure's collections are any less suited for static typing than Java's, it's just that we never bother declaring or casting.
09:05	Chouser	it might be an interesting excercize to try to write a DSL for asserting collection types.
09:05	blbrown	Chouser, I need to write a larger app in haskell and see if there are differences
09:06	leafw	Chouser: about the latter ... I had some not-so-nice experiences developing with clojure. For example, unless one is developing the program interactively, parts of the program may never be executed -- and bugs creep in that only show at run time. And some of this bugs are of the class/type kind, that a compiler or an IDE should catch.
09:06	Chouser	The simplest implementation would just be runtime checks, but it would allow you to play with the syntax to find something succinct and pleasing.
09:06	leafw	IMO, clojure is missing a nice IDE. What is the state of enclojure for net beans? And has net beans a proper text editor (like vim or emacs) integrated?
09:06	Chouser	leafw: yes, but if code is never run there can also be errors that the compiler and IDE won't catch.
09:07	blbrown	leafw, it is how you are coding that might introduce those bugs. For example, using TDD. Code a little, test a little, code a little helps a lot with clojure and other lisps
09:07	Chouser	a static typing compilier may catch some, but if you still need unit tests, and those unit tests would have caught the error too, what's the benefit of the static typing?
09:07	blbrown	same is kind of true for python or ruby
09:07	leafw	blbrown: I know, but one needs a nice IDE to do that. I should change to emacs just for that ... I use vim most of the time.
09:08	blbrown	I use emacs and vim, I haven't needed anything else
09:08	blbrown	of course, eclipse for project management
09:08	leafw	Chouser: I know; static typing is like a premature optimization, and an IDE should attempt to catch them all anyway.
09:08	Chouser	there's jvi that works with netbeans. last I tried it with enclojure it didn't work so well, but that may have changed.
09:09	blbrown	leafw, I see your point and had the same issue with python, when I started with that 10 years ago. But learned to use different coding styles when working with dynamic languages
09:09	Chouser	I submitted a patch ages ago, but I don't know if it ever went in.
09:09	leafw	guess I spent too much time doing things, even if slowed down, than testing IDEs that would speed me up.
09:09	leafw	blbrown: I had the same situation with python, is one of the reasons I don't use it so much (except for Blender).
09:09	blbrown	and I never was a big fan of debuggers, so I normally don't use those anyway. Unless debugging a complex web app
09:10	leafw	blbrown: debuggers for C are a must; at least for me.
09:10	blbrown	...one thing I thought about trying, kind of related. Is using a design by contract development style
09:11	leafw	blbrown: most of the time I develop in a exploratory way; no constraints (which has its good and its bad sides)
09:11	Chouser	leafw: most of my C experience was network device drivers. debuggers were almost completely useless, because as soon as you breakpoint the code, the world has already changed.
09:12	leafw	xD indeed. I am lucky then that all I do is crunching numbers.
09:12	bOR_	question about a stack overflow I am causing with merge-with.
09:12	bOR_	(apply merge-with concat (mapcat adaptedness (subvec (vec (gather :born)) 0 20)))
09:12	bOR_	works fine
09:12	bOR_	but somewhere between a vector of 2500-3000, it gives up.
09:13	bOR_	I've the code here, so I can parse more details if you need them.
09:13	bOR_	{(#{\A \B \C \D \E \F \G \H} #{\A \C \D \E \F} #{\A \C \D \E \F \G \H} #{\B \D \E \F \G \H} #{\A \B \C \D \E \F \H} #{\A \B \C \D \E \G \H} #{\A \F \H} #{\A\ \E \F \H} #{\A \B \C \D \E \G \H}) (5.660244012764965 5.935697382497301), (#{\A \C \D \E \F \G \H} #{\A \B \C \E \F \H} #{\A \B \C \D \E \F \G \H} #{\B \C \ \D \E \F \G} #{\A \B \C \D \F \G \H} #{\A \B \C \D \E \G \H} #{\A \B \C \D \F \G \H} #{\D \E \F} #{\A \C \D \E \
09:14	bOR_	that is its output: a hash-map in which the key is a particular pattern/genotype, and the val is a list of viral loads associated with that genotype.
09:15	bOR_	so it is doing what I want to do.
09:15	bOR_	but not for all 5000 hosts :).
09:15	drewr	Chouser: On the contributors page, can you change mtndrew0 -> aaraines?
09:16	Chouser	drewr: Based on the word of a random IRC nick? :-) Sorry, I don't know the rules.
09:16	drewr	haha
09:17	drewr	That was my sf ID, but since we're using Google now, I thought I'd use my Google one.
09:17	drewr	...and hate to bother rhickey for trivial changes like that.
09:18	Chouser	I think that's a good change to make, as then it matches your name on the issues page, but I don't know what kind of auth rhickey needs for that. Possibly email from that address asking for the change? I don't know.
09:18	drewr	That's fine, I'll email.
09:20	drewr	Make sure you check the headers of my message though. :-)
09:24	bOR_	hmmm. managed to circumvent the stack overflow by splitting my population in 3, doing the apply merge-with concat on each subpopulation and then doing an apply merge-with concat on the three answers.
09:25	Chouser	ick
09:26	bOR_	aint going to win any pretty-prizes :P.
09:26	Chouser	bOR_: can you put together a small runnable example that shows the problem?
09:26	bOR_	should be possible. I'll make a pot of tea and do that :).
09:30	rhickey	bOR_: mmmm, tea
09:32	bOR_	hehe
09:32	bOR_	water finished cooking, example done
09:32	bOR_	pasting it now :)
09:32	bOR_	(def noworld (map #(hash-map (rand-int 10) [%]) (range 25000)))
09:32	bOR_	ef yesworld (map #(hash-map (rand-int 10) [%]) (range 15000)))
09:33	bOR_	(apply merge-with concat yesworld)
09:33	bOR_	(apply merge-with concat noworld)
09:33	bOR_	that ef should be a def
09:33	bOR_	the yesworld works fine, the noworld gives a stackoverflow :)
09:34	bOR_	somewhere at concatting 2000 values to a single hashkey breaks it.
09:34	Chousuke	maybe try to make it less lazy?
09:35	bOR_	how would I do that?
09:35	Chouser	bOR_: nice, thanks for the example.
09:35	Chousuke	bOR_: use doall
09:36	Chousuke	like that, your world is just a lazy seq, so perhaps it'd help to realise it.
09:36	Chousuke	that puts it all in memory at once though.
09:36	bOR_	well, in the model, my world is a large vector of agents.
09:37	bOR_	is that the part you want me to make less lazy? not sure if I can change much there.
09:37	Chouser	,(apply merge-with concat (replicate 25000 {1 2}))
09:37	clojurebot	Eval-in-box threw an exception:java.lang.reflect.InvocationTargetException
09:37	Chouser	hm. that overflows for me
09:38	Chousuke	hmm :/
09:39	bOR_	shouldn't it be {1 [2]} ?
09:39	Chouser	yes
09:39	bOR_	can't concat 2.
09:39	bOR_	nod
09:40	Chouser	overflows either way, though, which is interesting.
09:42	bOR_	yeah, I wondered why. it has to remember three hashmaps. the collector, the first of the seq, and the rest of it. not sure why that would overflow.
09:42	Chouser	(reduce concat (replicate 25000 [2]))
09:43	bOR_	stack overflow as well here.
09:44	Chouser	yep, it's concat on more than 2 args that's recursive
09:44	bOR_	at quite a bit lower numbers than apply concat (replicate ..
09:44	bOR_	ah.
09:44	Chouser	oh, but... hm...
09:44	bOR_	am I supplying more than two args?
09:44	bOR_	hmm.
09:45	Chouser	oh!
09:45	Chouser	hm.
09:45	Chouser	no
09:59	Chouser	as soon as you realize a concat seq, it calls 'rest' on its first arg, which realizes the next lazy-seq, ... boom
09:59	bOR_	hehe.
10:00	bOR_	is it absolutely neccesary that it does that?
10:01	Chouser	seems likely there's another way to do it, but I haven't thought of it yet.
10:03	rhickey	(reduce concat ...) != (apply concat ...), for same reasons as (reduce str ...) != (apply str ...)
10:04	bOR_	noticed that. at first I switched to reduce rather than apply to see if that helped.
10:05	bOR_	(I know I don't know the difference well enough between the two, but that there was a forum post that explained it quite well if I needed to know the difference better)
10:05	rhickey	what's the failing case with apply?
10:07	bOR_	(apply merge-with concat (replicate 2500 {1 [2]}))
10:08	rhickey	bOR_: no problem here - are you trying to print it or something?
10:09	bOR_	hmm. if you use a larger replicate number than 2500?
10:09	bOR_	I'll see what happens if I just want it stored in a def.
10:09	bOR_	yes.
10:09	bOR_	matters if I just enter it in the repl, or send it to a def
10:10	bOR_	ahh.
10:10	bOR_	lemme see if that is the only problem in the original case as well.
10:11	bOR_	yep. it is the printout that happens in the repl that causes the stackoverflow.
10:11	rhickey	(count ((apply merge-with concat (replicate 250000 {1 [2]})) 1))
10:11	rhickey	StackOverflowError
10:12	bOR_	what is with the (( ?
10:12	bOR_	don't see that too often in code.
10:13	bOR_	hmm.
10:13	bOR_	never mind my confusion :)
10:13	rhickey	concat is such a bad operation for this
10:13	bOR_	it is only in a reporting function that I call once every 5 minutes.
10:14	rhickey	user=> (count ((apply merge-with into (replicate 250000 {1 [2]})) 1))
10:14	rhickey	250000
10:15	bOR_	into seems to work fine :)(
10:16	bOR_	what makes concat bad to use in this case?
10:25	bOR_	anyway, thanks for solving it. The endresult works fine: (mKsdge:#2703:^0.927:@6.40 mKsdqq:#1105:^0.515:@5.53 mKsdhj:#781:^0.422:@6.41 mKsdiP:#3\ :^0.252:@6.51)
10:28	rhickey	bOR_: it's expensive to add to the end of a list - we don't build up lists by saying (concat (concat (concat (concat () '(1)) '(2) ) '(3) ) '(4))
10:28	rhickey	which is effectively what you are asking for with reduce concat
10:36	bOR_	still a bit above my comfort level, but I'll keep it in mind. can't tell for example why into does fix this, but I'll figure that out over time.
10:38	Chouser	vectors are efficient for adding onto the right-hand side, which is what into does on a vector.
10:38	bOR_	ah. getting it. and concat is adding at the end of a list.
10:39	bOR_	so if the place in the list doesn't matter to me, conj would have been fine as well.
10:40	bOR_	because adding lefthand side in lists, is fine.
10:40	bOR_	nod.
10:40	Chouser	right. into and conj always add in the way that's efficient for the collection being used.
10:41	bOR_	I'll remember.
10:47	Chouser	the implementation of 'for' is hard to understand.
10:47	rhickey	Chouser: sorry
10:48	Chouser	:-)
10:48	Chouser	I've successfully patched it either without fully understanding it, or have since forgotten what I knew.
10:49	Chouser	I really want to tease out the shared structure between it an doseq.
10:50	clojurebot	svn rev 1313; swtiched to url.openConnection().getLastModified
10:57	thr	rhickey: I suppose you hear this hundreds of times a day, but I just started learning clojure (comming from C# and Python, wierd combo I know) and I've got to say this is... amazing, thanks so much for all your work!
10:57	rhickey	thr: you're welcome!
11:11	thr	Btw, Am I allowed to ask "newbie"-style questions about clojure in here? Reading about it and trying out examples and find something that is a bit ambigius to me
11:12	Chouser	thr: sure
11:12	thr	I have this example that adds an extra metadata tag to shout: (defn #^{:tag String} shout [#^{:tag String} s] (.toUpperCase s))
11:12	thr	Displaying it with ^#'shout seems to work fine
11:12	thr	but the thing that got me was the fact that #^{:tag String} is infront of the symbol s in the argument list also
11:13	thr	removing the #^{:tag String} from the argument vector, everything still seems to be the same when running ^#'shout in the repl
11:14	Chousuke	the latter actually applies to s
11:14	thr	Yeah I figured that, but where is it any good ?
11:14	thr	I mean, you can't access s anywhere
11:14	leafw	can one specify the return type of a function? That is news to me
11:14	Chousuke	type hinting.
11:14	thr	Chouser: aha!
11:14	thr	Thanks
11:15	Chousuke	though That's usually done with #^String isn't it? :/
11:15	Chouser	those are type hints. If Clojure can't tell what method to call because of insufficient type hints, it will figure it out at runtime.
11:15	Chouser	Chousuke: yep, that's a shortcut for what he's got.
11:15	blbrown	stupid general question: with clojure (defn abc [something] (.doIt something)) ...(abc something1-obj) ... (abc something2-obj) ...being able to call abc on two different objects. would that be considered 'polymorphism' or something else. And should lisp be used in this fashion. Or is defmethod a better tool for that
11:16	Chouser	thr: the defn macro actually can access the metadata on s
11:16	thr	Thanks a bunch for the help guys, most appriciated
11:18	Chousuke	blbrown: I guess that's polymorphism, yes. and it's perfectly fine
11:20	Chousuke	blbrown: defmethod is for when you want different behaviour based on some function of the parameters
11:20	Chouser	if something1-obj and something2-obj are two different classes, with their own doIt() method definitions, that's normal Java polymorphism.
11:20	blbrown	Chousuke, I am working on a small test framework. I can create simple mock objects for the test cases and then pass the mock objects to my library functions. But in the real world, I can just use the real objects
11:21	blbrown	kind of an interesting approach
11:21	Chousuke	Chouser: except they don't even have to have a common parent.
11:21	Chousuke	or implement a common interface.
11:21	blbrown	Chouser, yea, what chousuke said
11:22	Chousuke	for testing java?
11:22	blbrown	and I guess with other lisp's it may not be as prevalent because those lisp aren't wrapped around an object oriented language runtime
11:23	Chousuke	there are many clojure test frameworks that do just fine without mock objects :)
11:23	blbrown	Chousuke, I don't really need mock objects, but I could if need be
11:25	blbrown	Chousuke, defmethod seems more like how erlang's pattern matching works
11:28	Chousuke	defmethod does no pattern matching though.
11:29	Chousuke	but I don't know Erlang so I can't say much
11:30	blbrown	Chousuke, it seems like it
11:30	cemerick	is it the case that array classes cannot currently be used as part of gen-class method or constructor signatures?
12:15	blbrown	wtf is waterfront
12:16	gnuvince_	An editor
12:24	blbrown	ah
12:52	danlarkin	Lau_of_DK: Nantes?
13:08	Lau_of_DK	danlarkin: What does that mean ?
13:09	danlarkin	it's a city in France
13:12	Lau_of_DK	Its not bad - Dont know the city though - How 'bout Tokyo ?
13:15	Lau_of_DK	dk.bestinclass.sofiaba> (Vector3f. 1 1 1)
13:15	Lau_of_DK	#<Vector3f com.jme.math.Vector3f [X=1.0, Y=1.0, Z=1.0]>
13:15	Lau_of_DK	dk.bestinclass.sofiaba> (Vector3f. (apply float [1 1 1]))
13:15	Lau_of_DK	; Evaluation aborted.
13:15	Lau_of_DK
13:15	Lau_of_DK	Whats the trick ?
13:26	Chouser	what you have there is the same as (Vector3f. (float 1 1 1))
13:26	Lau_of_DK	Yea ... so whats the trick ?:)
13:26	Lau_of_DK	Its a destructuring of some kind I need
13:36	Chouser	(defmacro mapmac [t f c] (cons t (map (eval f) c)))
13:36	Chouser	(mapmac Vector3f. #(do `(float ~%)) [1 1 1])
13:38	cmvkk	,(- 1.33 1)
13:38	clojurebot	0.33000000000000007
13:40	cmvkk	is that just some weird floating point thing or what?
13:57	durka42	looks like floating point stuff to me
13:58	cmvkk	is there any good way to take x.33 for any x and reliably return 0.33?
13:58	cmvkk	maybe it's just me, but i feel like that ought to be feasable...
14:00	durka42	you could use fixed-point math...
14:00	durka42	,(- 1.33M 1M)
14:00	clojurebot	0.33M
14:00	cmvkk	oooh
14:00	durka42	which is weird because...
14:00	durka42	,(- (BigDecimal. 1.33) (BigDecimal. 1))
14:00	clojurebot	0.3300000000000000710542735760100185871124267578125M
14:01	cmvkk	heh
14:01	durka42	apparently bigdecimal literals are not just bigdecimal literals
14:01	durka42	,(= 1.33M (BigDecimal. 1.33))
14:01	clojurebot	false
14:02	cmvkk	well
14:02	cmvkk	,(BigDecimal. 1.33)
14:02	clojurebot	1.3300000000000000710542735760100185871124267578125M
14:03	cmvkk	it isn't the same number anyway.
14:03	durka42	right that's why i was confused
14:03	durka42	i guess it's because 1.33 literal is converted to a double first and then a bigdecimal
14:03	dreish	That's the exact value of the floating-point number 1.33.
14:03	durka42	instead of
14:03	durka42	,(BigDecimal. "1.33")
14:03	clojurebot	1.33M
14:03	cmvkk	oh hmm
14:11	thr	How are clojure vectors implemented? I assume lists are linked lists, but vectors?
14:11	dreish	They're actually trees.
14:11	thr	Ok, thanks
14:12	thr	dreish: you know what tree algorithm they're implemented as?
14:12	thr	(just curious, not that it matters for me at this point ;p)
14:13	dreish	I can't remember what it's called, but they're 32-way trees. You can see the code in PersistentVector.java
14:13	dreish	It's pretty clever.
14:13	thr	Ok, thanks a bunch - yeah figured it'd be clever ;p
14:13	thr	just curious of the inner workings for no other reason than it's fun to know
14:13	dreish	Indices 0-31 go in the root node, then 32-63 in the first child of that node, etc.
14:14	dreish	I think. I might be describing it incorrectly.
14:14	thr	Hm... I'd figure it would be a b-tree with 31 slots per node
14:15	thr	Because I think the way you said would give horrible performance when searching
14:15	thr	not sure though, semi-professional-guess
14:15	dreish	Really?
14:15	dreish	You always know exactly what path to follow to get to a given index.
14:16	thr	Ah, I totaly missunderstood you
14:16	thr	I thought you ment 0-31 (root) -> 32-63 (31) etc.
14:17	dreish	The code in clojure/lang/PersistentVector.java is more authoritative than anything I could say about it.
14:18	thr	Yeah Ill go check it out, love digging around in the inner works of stuff
14:18	dreish	That's one nice thing about Clojure -- it's small enough that that's easy to do.
14:18	thr	Yeah, I've just been toying with it for not very long, and it's my first Lisp but I do really enjoy it so far
14:19	kotarak	thr: may be of interest to you: http://blog.higher-order.net/2009/02/01/understanding-clojures-persistentvector-implementation/
14:20	thr	thanks :)
14:21	pjb3	so, there's no way to use binding with out a root binding, right?
14:21	pjb3	,(binding [x 1] x)
14:21	clojurebot	java.lang.Exception: Unable to resolve var: x in this context
14:22	dreish	Oh, of course, the root node _becomes_ the first child node once the tree expands past 32 items.
14:24	thr	yeah that is clever
14:25	thr	And the implementation is only ~200 lines? Goddamn I'm impressed
14:26	rhickey	pjb3: you can use binding without a root binding, but not without a var: (def v) ... (binding [v foo]...)
14:26	Lau_of_DK	kotarak: Sweet article, thanks
14:27	kotarak	Lau_of_DK: it's not by me, of course. I just saw some weeks ago in reddit.
14:27	pjb3	rhickey: right, ok
14:27	Lau_of_DK	rhickey: The 0.5F issue we discussed isnt a pressing as I thought, it seems in most cases Java will automatically convert doubles to float when needed
14:27	cmvkk	i need a data structure i can use as a queue but still has good random access. I was using a vector but it keeps overflowing the stack. Maybe i'm doing it wrong?
14:28	dreish	cmvkk: PersistenQueue.
14:28	dreish	t
14:28	rhickey	dreish: PQ doesn't have random access
14:28	dreish	Oh, I didn't notice that.
14:29	dreish	Wouldn't it be easy to add, since it's just a seq on a vector plus a vector?
14:29	cmvkk	i was pushing with conj and popping off the beginning with subvec. is the fact that this blows the stack expected?
14:34	rhickey	cmvkk: currently, subvecs stack, i.e. subvec on a subvec on a subvec builds a chain, will fix...
14:41	Lau_of_DK	Its the cemerick! :)
14:42	cemerick	THE cemerick?
14:42	cemerick	I've noticed a couple of people with handles like that -- the_joe_smith, etc.
14:43	Chouser	The Astute Chas, of the House of Emerick.
14:54	Lau_of_DK	cemerick: Since you got that mention from Norvig I figured you'd go with The Cemerick from now on :)
14:55	cemerick	heh. The fanboy glee has since faded. :-)
14:56	WizardofWestmarc	mention from Norvig?
14:57	mattrepl	what Norvig mention is this?
15:01	arohner	mattrepl: http://norvig.com/ibol.html
15:01	arohner	http://blog.snowtide.com/2009/02/26/whoa-peter-norvig-used-some-of-my-code
15:06	mattrepl	nice, congrats, cemerick. didn't connect your real name to you when read first time
15:06	arohner	what's the syntax if I want a macro to refer to a symbol?
15:06	arohner	~'foo ?
15:06	clojurebot	excusez-moi
15:07	dreish	For symbol capture, yes.
15:07	Lau_of_DK	I have a macro which generates code, which produces some data, I want to call this macro from a function, but I dont want the resulting code, which generates data, I want the data - How do I do? (eval (mymac foo bar)) doesnt do it
15:07	cemerick	mattrepl: thanks
15:07	dreish	arohner: It's filthy, but I do it all the time. :)
15:08	arohner	dreish: I'm doing it for a one-off that will only be used on this page
15:08	arohner	it cleans up the code significantly IMO
15:08	dreish	Yeah, sometimes it really is useful.
15:08	cemerick	Lau_of_DK: try (eval '(mymac foo bar))
15:09	cemerick	,(eval '(and false true))
15:09	clojurebot	DENIED
15:09	cemerick	eh, it doesn't allow eval
15:09	cmvkk	heh
15:09	WizardofWestmarc	Hah that's really cool cemerick :)
15:09	cmvkk	why doesn't the macro get evaluated automatically?
15:09	durka42	Lau_of_DK: what does the eval do? i would expect that to work
15:10	kotarak	Lau_of_DK: why is it a macro generating data not a function?
15:10	Lau_of_DK	Its the only way to go because I need some destructuring
15:10	clojurebot	svn rev 1314; avoid chaining in subvec of subvec
15:10	cmvkk	yeah but, when a macro returns code, that code is evaluated right then, right?
15:11	cmvkk	ooh thanks rhickey
15:11	rhickey	cmvkk: its' still not a queue though
15:11	dreish	That was sudden. :)
15:12	Lau_of_DK	Cemerics trick, did it
15:12	cmvkk	no; well i don't know how else to do what i want to do in any sort of efficient way
15:12	rhickey	since memory is not reclaimed from front
15:12	Lau_of_DK	cmvkk: I thought so - but no
15:13	cmvkk	oh. i don't suppose it would be a good idea to use (into [] (rest myvec)) instead?
15:13	durka42	(eval '(mymac foo bar)) is the same thing as (mymac foo bar), isn't it?
15:13	durka42	maybe (mymac 'foo 'bar)
15:13	rhickey	cmvkk: no, would be very bad perf
15:13	cmvkk	yeah, that's what i thought
15:14	cmvkk	but anything rest returns is O(n) random access?
15:14	arohner	does the #() form work inside of macros?
15:14	ayrnieu	,`(does #(%) work?)
15:14	clojurebot	(sandbox/does (fn* [sandbox/p1__2847] (sandbox/p1__2847)) sandbox/work?)
15:14	rhickey	cmvkk: right, seqs are linear access
15:15	arohner	ayrnieu: I did that, but got "can't use name as qualified parameter"
15:15	ayrnieu	arohner - what do you get that from?
15:15	ayrnieu	oh, actually, I see
15:16	arohner	and translating to "normal" (fn [x#] x#) works fine
15:21	ayrnieu	`(does (fn [%] %) work?)
15:21	ayrnieu	,`(does (fn [%] %) work?)
15:21	clojurebot	arg literal not in #()
15:21	ayrnieu	huh.
15:21	ayrnieu	,`(does (fn [a] a) work?)
15:21	clojurebot	(sandbox/does (clojure.core/fn [sandbox/a] sandbox/a) sandbox/work?)
15:21	durka42	(fn [a] a) != #(%)
15:23	dreish	rhickey: There's no technical reason with a little reworking nthrest couldn't be made O(1) for seqs on random-access structures, right? Just hasn't been done?
15:24	rhickey	dreish: for what purpose?
15:24	rhickey	seq + subvec
15:24	dreish	rhickey: None right now. It was just a thought -- I don't really care when if ever it happens.
15:29	ayrnieu	dreish - even if it were O(1), a series of nthrests on a random-access structure would require memory allocation. nthrest makes sense for sentineled data structures -- C strings, cons lists, where every subrest is already a proper data structure.
15:47	Lau_of_DK	http://paste.lisp.org/display/76291 <-- Could someone, with macroskillz like rhickey, please tell me why this boorks - I really dont understand how evaluation is handled
15:48	kotarak	(eval `(>RGBA ~v))
15:50	Lau_of_DK	Unable to resolve v in this context
15:51	ayrnieu	Lau - look at (macroexpand-1 '(>RGBA v))
15:52	ayrnieu	you don't need to use eval; the bare macro is sufficient.
15:55	Lau_of_DK	ayrnieu: Thats gives me that ISeq error
15:57	ayrnieu	OK, now try (ColorRGBA. (map (fn [x] `(float ~x)) 'v)) :-)
15:58	ayrnieu	you're doing work at macroexpansion time. You don't have the value of v at macroexpansion time -- you just have 'v itself.
16:00	kotarak	clojurebot: eval
16:00	clojurebot	Pardon?
16:00	kotarak	clojurebot: eval is evil
16:00	clojurebot	c'est bon!
16:01	kotarak	clojurebot: eval is also sometimes useful - but only sometimes
16:01	clojurebot	'Sea, mhuise.
16:01	durka42	clojurebot: eval is also DENIED
16:01	clojurebot	Ack. Ack.
16:01	Lau_of_DK	Hmm, Im further now, but my setup is too complicated to see if its entirely working atm, but big thanks to ayrnieu and kotarak :)
16:02	kotarak	np
16:03	Lau_of_DK	Guys - its working, love this community
16:04	Lau_of_DK	I new have a beautiful 3d island, fully detail textured, rendered on a slowly moving pacific ocean! :)
16:04	Lau_of_DK	k
16:04	slashus2	screenshots?
16:05	Lau_of_DK	Hang on
16:06	slashus2	Lau_of_DK: Are you sure that you had to use a macro in that case?
16:08	WizardofWestmarc	hm, strange
16:08	WizardofWestmarc	trying to get clojure working in my ubuntu vm... and when I load slime it looks for util.clj
16:09	slashus2	(defn >RGBA [vektor] (ColorRGBA. (map (fn [x] (float x)) vektor))) won't work?
16:09	Lau_of_DK	http://wiki.github.com/Lau-of-DK/sofiaba
16:10	Lau_of_DK	slashus2: There u go - And yea, I needed a macro, which will be used several places for more than just this purpose
16:10	durka42	awesome
16:10	durka42	it looks... grainy
16:11	Lau_of_DK	Yea - texture is too detailed
16:11	Lau_of_DK	I think it'll work once I scale it up to full playable size
16:13	durka42	what's the speed like?
16:13	Lau_of_DK	Its like... awesome
16:13	Lau_of_DK	Before I added the water it ran at about 800 fps, I havent tested, but I'll add an fps counter soon, Im just in the middle of wrapping and extending functionality
17:01	dpthfltr	ok this is going to be a very very simple question ;) I have two strings and I want to create a seq that contains both.
17:01	dpthfltr	what function can I use ?
17:02	rhickey	dpthfltr: (list s1 s2)
17:27	hiredman	,(into-array Character/TYPE "foo")
17:27	clojurebot	#<char[] [C@14d0183>
17:30	Lau_of_DK	http://github.com/Lau-of-DK/sofiaba/tree/master, for those following this, Ive pushed a massive change provinding quite a few wrappers, screenshots on the wiki - I stripped jmephysics, because its quite problematic in its current state
17:31	rhickey	name game again - I'm thinking of letfns for Clojure's letrec/labels
17:32	Lau_of_DK	example? Im not following
17:33	rhickey	http://paste.lisp.org/display/76297
17:34	ayrnieu	rhickey - why not 'flet' ? It implies something different in CL, but so does LET ; and {'let* 'let, 'labels 'flet} seems consistent.
17:35	ayrnieu	and you can pronounce it instead of sort of mumbling it.
17:35	Lau_of_DK	rhickey: Rich does this have a wider application that Im not seeing, because to me it seems like its just adding bloat to Clojure
17:36	ayrnieu	s/implies/means/
17:36	rhickey	Lau_of_DK: mutually recursive local fns are not currently possible
17:38	Lau_of_DK	oh I see, its like a built in trompoline
17:38	gnuvince_	rhickey: would letfns have a different syntax? something like (letfns [f [x y] (+ x y), g [a b c] (* a (- c b))] body)?
17:38	Lau_of_DK	letfns sounds good to me, it fits well with the rest of clojure
17:38	gnuvince_	Or regular [f (fn [] (...))] ?
17:39	ayrnieu	letrec [also pronounceable] would have the usual syntax, and also work for mutually recursive data structures.
17:40	gnuvince_	Oh, I see you already posted code
17:41	ayrnieu	let-fns corresponds to let-if
17:41	gnuvince_	letfns is fine by me. labels doesn't really scream functions.
17:42	rhickey	gnuvince_: sample: http://paste.lisp.org/display/76297
17:43	rhickey	gnuvince_: right, labels is definitely out, flet has reverse implications
17:43	rhickey	letrec is more general
17:43	rhickey	this is for fns only
17:43	gnuvince_	rhickey: does it support multiple-arity functions?
17:44	gnuvince_	(letfns [(f ([x] x) ([x y] (+ x y)))] ...)?
17:44	rhickey	gnuvince_: sure
17:45	gnuvince_	Then it looks just damn fine to me :) The name is well chosen, the syntax is pretty good.
17:45	rhickey	I like flet, concerned about the reverse implication
17:45	Lau_of_DK	flet is awful
17:45	Lau_of_DK	:)
17:46	rhickey	I always wished that flet did what labels did, hate the name labels
17:46	ayrnieu	anyone bothered by flet has gotten over being bothered by let
17:46	Lau_of_DK	oh, I just realized I hate it because its a danish name for certain way of styling your hair. :)
17:46	rhickey	there's also letf
17:47	rhickey	letfn (not plural)
17:48	ayrnieu	let-fn again, like let-if
17:48	rhickey	ayrnieu: are you asking for a dash?
17:48	gnuvince_	between letfns and letfn, I think I'd go with letfn
17:50	ayrnieu	rhickey - I'd prefer that to letfn
17:51	rhickey	ayrnieu: dash unlikely, sorry. if-let when-let etc are two-step things
17:53	gnuvince_	rhickey: you have notes from 3 years ago?
17:54	rhickey	yeah, all the Clojure design was done in Mac apps Notebook and OmniGraffle, Notebook has nice creation date view
17:55	rhickey	dozens of variants of fn syntax on same page :)
17:55	gnuvince_	cool
17:55	gnuvince_	Do you have notes on where you expected Clojure to be three years from then? :)
17:56	rhickey	nope, just tech specs, no way to have planned what happened
17:58	gnuvince_	I hope you're happy with where you are, it's truly amazing the explosion Clojure has seen in a little over a year in the public eye.
17:58	rhickey	gnuvince_: it's crazy
18:00	gnuvince_	bbl, diner
18:07	duncanm	i'm trying to use slime on linux, and i see this error when i load it up: java.lang.Exception: Unable to resolve symbol: lazy-seq in this context (core.clj:70)
18:10	slashus2	Is there a safe way to do io inside of a transaction? I was looking at the io! macro.
18:11	rhickey	slashus2: you can send to an agent which does the io after the transaction commits, otherwise no, because transactions can retry
18:12	hoeck	duncanm: are you using latest slime & latest clojure (github/svn versions)?
18:13	hoeck	duncanm: i mean the latest jochu-swank-clojure, not slime, sorry
18:14	slashus2	Okay, didn't think of sending it off to an agent.
18:20	clojurebot	svn rev 1315; added letfn, supports mutually recursive local fns
18:23	slashus2	something like (send (agent @overall-count) println) sometimes prints two numbers beside each other in the output.
18:24	slashus2	I am trying to do the producer consumer simulator.
18:25	slashus2	Trying to print out when the producer produces a new number.
18:30	Lau_of_DK	hoeck: I updated SofiaBA heavily, and initially I had to write out jMephysics, because its unstable in its current state - sorry if I got your hopes up
18:30	Lau_of_DK	Its not dropped, its just postponed a little bit
18:31	slashus2	http://pastebin.com/d61e802a3
19:51	Chouser	we could just hook the svn change feed directly to reddit
19:51	rhickey	heh
19:52	rhickey	yeah, some of it isn't going to do anything but make people bored/annoyed
19:52	ayrnieu	This Week in Clojure
19:53	Chouser	ahem not to demean your latest feature, of course. :-)
19:53	rhickey	one more wart removed
19:53	gnuvince_	Speaking of TCO (again), is there any word if Sun is going to include it in JDK7?
19:55	rhickey	unlikely in 7 I think, but there's an implementation in MLVM already
19:55	Chouser	I'm much more interested in tagged numbers
19:55	rhickey	I haven't tried MLVM yet, nor do I know what I'd have to do to enable it
19:56	Chouser	though I guess TCO would be a PR win.
19:56	rhickey	Chouser: tagged numbers even further away I'm afraid
19:56	Chouser	am I right in thinking they would removed the need for most of the explicit primitive declarations?
19:58	rhickey	Chouser: TCO would be genuinely nice, not for loops, but for chained function calls on indefinite input, state machines etc
19:58	rhickey	Chouser: tagged numbers have their own tradeoffs, #1 being that they lose a few bits vs. the machine word
20:01	rhickey	[11:17am] Chouser: but this does not:
20:01	rhickey	Cl-USER 4 > most-positive-fixnum
20:01	rhickey	536870911
20:05	gnuvince_	So numbers would be 29 bits if they were tagged?
20:06	rhickey	gnuvince_: depends on the tagging scheme
20:06	gnuvince_	byte, short, int, long
20:06	gnuvince_	Hmmm
20:06	ayrnieu	byte, short, int, long, tagged fixnum
20:07	rhickey	http://blogs.sun.com/jrose/entry/fixnums_in_the_vm
21:10	hiredman	I don't suppose anyone has tried/got to work serving content from an inputstream with ring?
21:36	Chouser	whee! http://paste.lisp.org/display/76305
21:37	gnuvince_	damn!
21:38	hiredman	;_;
21:38	ayrnieu	well, at least it pretty-printed
21:39	hiredman	ugh
21:39	Chouser	I pretty-printed it manually. :-/
21:39	hiredman	how can I pack a binary array into a string?
21:40	gnuvince_	speaking of which, whatever happened to the pretty printing project?
21:40	hiredman	er
21:40	hiredman	byte array
21:41	cmvkk	what, like base64 encoding or something?
21:41	Chouser	hiredman: String has a constructor that takes byte[]
21:41	rhickey	Chouser: hmm... an early version of the Clojure compiler removed (let []) and (if true ...)
21:42	hiredman	Chouser: yeah, but it doesn't seem to work well with a byte[] filled with jpeg data
21:42	Chouser	hiredman: sounds like a poor fit for a String. why do you want it?
21:43	ayrnieu	he's pretending that sockets are files, is why.
21:43	hiredman	because ring can serve content from a string
21:43	Chouser	ayrnieu: files can't store bytes??
21:43	Chouser	hiredman: sounds like ring could use a new feature.
21:43	cmvkk	what's ring?
21:43	hiredman	yeah
21:44	hiredman	I would really like to serve right from the inputstream I have
21:44	hiredman	~ring
21:44	clojurebot	ring is http://github.com/mmcgrana/ring/tree/master
21:45	hiredman	looks like adding that might be easier then I thought
21:46	hiredman	actually
21:46	hiredman	it looks like it should already work
21:56	hiredman	ah
21:56	hiredman	excellent
21:56	hiredman	that does work
21:56	hiredman	I must have been doing something wrong before, but now ring serves out of a CipherInputStream just fine
22:16	Drakeson`	Which virtual machine hosting you recommend/had success with? (to deploy clojure web applications, etc.)
23:13	mattrepl	Drakeson: http://slicehost.com is nice
23:16	Drakeson	thanks
23:30	cp2	Drakeson i have a vps with http://cheapvps.co.uk/
23:30	cp2	if you dont have a lot of money to spend, they are worth it
23:30	cp2	provided you can deal with managing it yourself
23:43	Drakeson	cp2: great. thanks. I want something that I can manage myself.
23:45	Drakeson	cp2: [sorry to ask this stupid question] is the term "VPS" what I have to search for?
23:46	cp2	huh?
23:47	Drakeson	I mean, is VPS hosting what I am looking for?
23:47	cp2	well, i guess
23:47	cp2	you said virtual machine hosting
23:47	cp2	vpses are virtualized dedicated servers
23:47	cp2	there are several on a big honkin' server
23:48	Drakeson	I was looking for the right term to google it. virtual machine hosting wasn't the right term ;)
23:48	cp2	heh
23:48	cp2	yeah, vps would be better
23:48	Drakeson	cp2: cool. thanks.
23:48	cp2	also, i would check http://www.webhostingtalk.com/
23:49	cp2	lots of reviews and such about providers
23:50	Drakeson	nice, there is a whole VPS hosting board there (in webhostingtalk)
23:50	cp2	yep