#clojure log - Mar 25 2011

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0:03 amalloy: i wish there were a way of doing the following that didn't involve messing around with vectors just for temporary holders: (apply myfn (if some-test [0] '[whoa not 0]))

0:08 i could require that there be a one-arg case, which comes first, but ideally the compiler would magically know where i want to split the two halves of the if clause

0:08 devn: amalloy: once upon a time I actually had some code to generate docs and counted the number, but it's been awhile

0:08 and lots of the stuff in .core is not relevant for most programs

0:08 and by lots i mean...a little bit

0:09 amalloy: devn: i was just making fun of 4-600, which you intended to mean 400-600

0:09 devn: oh, right...

0:09 i think clojure only has like...4 functions...

0:09 +, -, quot, and

0:09 that's all.

0:09 amalloy: it only has like four data types, so four functions should be fine

0:10 devn: madness! why would you include + if you have -?

0:10 &(- 10 (- 4))

0:10 sexpbot: ⟹ 14

0:10 devn: amalloy: it's like car/cdr, except more hardcore

0:11 amalloy: &(let [+ (fn [& args] (- (apply - 0 args)))] (+ 10 20)]

0:11 sexpbot: ⟹ 30 ; Adjusted to (let [+ (fn [& args] (- (apply - 0 args)))] (+ 10 20))

0:12 devn: :D

0:12 amalloy: $botsnack

0:12 sexpbot: amalloy: Thanks! Om nom nom!!

0:13 devn: I think it'd be fun to make $botsnacks /necessary/ for a bot to cooperate in the channel

0:13 like it just refuses to pay attention to you until you give it a few snacks and pet it

0:14 amalloy: devn: i'm sorely tempted to turn off the clojure plugin

0:14 so that you realize the horror

0:14 (dec amalloy)

0:14 sexpbot: You can't adjust your own karma.

0:14 devn: amalloy: speaking of which, i heard you were toying with sexp/irclj to build a sort of generalized framework

0:14 amalloy: wut. i'm not, srsly

0:14 Raynes might be

0:15 devn: i dont like that whole fnmap thing

0:15 amalloy: i mean, sexpbot already is a generalized framework, what more do you want?

0:15 devn: multimethods dont make it much cleaner

0:15 amalloy: it's too fat -- needs to be stripped down

0:16 amalloy: you were saying this to Raynes months ago, weren't you? i don't think either of us got what you wanted

0:16 devn: i was thinking about cond-let, fcase, or something to clean up the condp

0:17 amalloy: i mean, the whole thing is less than 600 lines if you don't count the entirely-optional plugin dir

0:17 * devn nods

0:17 amalloy: including blank lines and comments

0:17 devn: i just think that fnmap is 'unclean' -- and there is some elegant solution but im still not quite sure what it is

0:17 amalloy: ping me when you've mastered human-computer telepathy

0:18 devn: via telepathy or by typing it into the window?

0:18 amalloy: the latter would be less impressive

0:19 devn: i think the ultimate taunt would be to tell someone you've actually figured out a neural interface for your computer, but you refuse to share it, and you do so via your neural interface

0:21 "Jesus, how the heck to do anything?"

0:22 groovy2shoes: devn: that's my favorite so far.

0:24 devn: groovy2shoes: favorite what?

0:25 groovy2shoes: devn: favorite post on the group

0:25 it made me giggle inside

0:25 devn: heh -- i need to review the thread -- if no one has posted a link to stuart halloway's "simplicity" talk they need to

0:26 "why dont i already know how to fly a plane despite the fact i have absolutely no training"

0:33 amalloy: devn: you don't know how to fly a plane? i can fly seven at once

0:47 mec: did java ever add invoke dynamic?

0:50 amalloy: mec: java 7

0:50 that said, people more informed than i tell me it's not that interesting from clojure's POV

0:51 mec: oh?

0:52 scottj: people as in rhickey :)

0:53 amalloy: scottj: i think it's fair to say he's better informed than i about clojure. maybe a close call, but i have to back down on that one

1:00 mec: Maybe clojure isnt as dynamic as I thought, rhickey does happen to be a wiz at interfaces

1:01 scottj: clojure isn't OO like the languages that need invoke dynamic

1:03 amalloy: scottj: that's a much clearer statement than the ten-thousand-page summary i read of why jruby luvs invokedynamic

1:12 devn: amalloy: link me?

1:12 (to the jruby summary)

1:12 amalloy: uhhh

1:13 it was...on twitter like a month ago

1:13 maybe it was http://blog.headius.com/2008/09/first-taste-of-invokedynamic.html

1:13 but that's years old

1:14 i think that's it, all the same

1:14 mec: well invoke dynamic has been around for like 5 years

1:15 amalloy: mec: sure, i'm just surprised something this old would get tweeted about recently

1:15 mec: I just watched a presentation on it from '07 and i figured it had to be in the JVM by now :D

1:20 hiredman: apparently the jvm guys askes rich what changes he would like to see in the jvm, he said just do what you do better and faster

1:20 mec: and tco ;p

1:21 hiredman: well, I for one would love to see tco

1:21 but it doesn't seem to be high on anyone's priorities

1:22 http://www.infoq.com/presentations/Towards-a-Universal-VM

1:22 mec: It would just make trampoline faster right?

1:22 hiredman: clojurebot: towards

1:22 clojurebot: Excuse me?

1:22 hiredman: clojurebot: ~search for towards

1:22 clojurebot: <#clojure:hiredman> clojurebot: towards

1:22 <#clojure:hiredman> http://www.infoq.com/presentations/Towards-a-Universal-VM

1:22 <#clojure:mids> fliebel: "Shifting right by n bits on an unsigned binary number has the effect of dividing it by 2n (rounding towards 0)."

1:22 <#clojure:devn> but most of clojure is geared towards making the things you do pure by default

1:23 hiredman: mec: it would make a lot of interesting control flow abstractions possible and faster without using trampoline

1:24 mec: Would you have an example? I dont know that i've even ever used trampoline

1:25 hiredman: mec: state machines

1:26 mec: I think I saw an example of that in scheme

4:26 xkb: hi again :)

4:26 Still puzzling with my DP boxes problem

4:26 how would you translate this piece of code:

4:26 for (int i=0;i<numBox;++i) {

4:26 for (int j=0;j<numBox;++j) {

4:26 if (i==j) continue;

4:26 if (graph[i][j] && level[i]+1 > level[j]) {

4:26 level[j] = level[i]+1;

4:26 prev[j] = i;

4:26 }

4:26 }

4:26 }

4:26 to clojure?

4:27 sry for the paste..

4:27 I'm thinking of (map .. (map ..))

4:28 raek: nested (for [..] (for [..] ....)) could be one approach

4:28 xkb: the main problem I'm having is translating the "side-effects" of the code to something more functonal

4:28 e.g. level[] and prev[]

4:29 raek: but note that the imperative programming paradigm and the funtional programming paradigm are very different from each other

4:29 xkb: :)

4:29 raek: so you can't in general translate code directly

4:29 xkb: That's why i'm looking for a more functional approach

4:29 something like an accumulator springs to mind

4:29 or actually 2 in this case

4:33 TobiasRaeder: Morning

4:36 raek: the "looping" could be made easily with loop/recur, but can't at a glance really see what the data dependencies of the generetated level and prev values are

4:38 xkb: this is an interesting problem, but I gotta go. there will probably be more people active here when USA wakes up

4:47 hoeck: xkb: I don't really know how to work with matrices in a functional way, so my approach would be to just translate this code line by line to clojure

4:47 xkb: like https://gist.github.com/886553

4:47 ejackson: hey all

4:49 TobiasRaeder: Good Morning :)

9:15 kensho: fliebel: I played a bit with Java2D and the JMonkeyEngine but I haven't made any real game

9:47 tsdh: Hi guys.

9:48 Can anyone see if I could formulate these functions in a more performant way (especially the iseq defmulti at the bottom)? http://pastebin.com/Qm8P4xD5

9:49 One problem is that `type-matcher' is called gazillions of times, which might be a bottleneck. However, memoizing that makes it even slower...

9:51 angerman: if you are dispatching on class anyway, why not use protocols?

9:52 tsdh: Because I'm new to clojure and haven't used them till now. ;-)

9:52 Do you think that will perform better?

9:54 angerman: could only assume. don't know for sure.

9:54 Havvy: I have Clojure load from C:/Clojure/clojure.jar and I want it to load the file at C:/Havvy/Code/LISP/converter.clj

9:54 How would I do this?

9:55 angerman: (load "C:/Havvy/Code/LISP/converter.clj") ?

9:55 stuartsierra: load-file

9:55 clgv: what do you guys use when you want to have an exception-like behavior? clojure.contrib.condition?

9:55 stuartsierra: clgv: exceptions

9:56 clgv: hm but I would have to define a custom one since I want only to handle the special case I am throwing on.

9:56 cemerick: stuartsierra: I think your days on 20% /core duty are making you even snarkier. :-D

9:57 stuartsierra: cemerick: Not possible. :)

9:57 clgv: Rich's recommended approach is a dynamically-bound Var with your error-handling function.

9:58 cemerick: By the way, how can I sign the Clojure 1.2.1 JAR to upload to Sonatype?

10:00 cemerick: stuartsierra: Good question. The release plugin takes care of that automagically, I've never had to do it manually.

10:00 stuartsierra: maybe http://maven.apache.org/plugins/maven-jarsigner-plugin/sign-mojo.html ?

10:00 which appears to wrap jarsigner: http://download.oracle.com/javase/6/docs/technotes/tools/windows/jarsigner.html#Options

10:01 stuartsierra: ok, thanks, will investigate

10:03 tsdh: angerman: I looked at protocols, but since I dispatch on the class of external Java objects, I think I would need to reify them. That doesn't sound better, does it?

10:04 angerman: tsdh: you'd basically write your protocol and then extend the java types.

10:05 someone please correct me if i'm wrong.

10:06 TobiasRaeder: That seems like the way to do and i think (can't provte it right now) that it "should" still be faster using protocols + extend-type than using multimethods

10:06 angerman: (defprotocol Foo (foo [_] "does foo"))

10:06 (extend-type java.lang.String Foo (foo [_] "whatevaaaa"))

10:06 (foo (String. "Hi"))

10:07 ;; => "whatevaaaa"

10:07 tsdh: angerman: Hm, Vertex is the top-level Java class in a probably large, dynamically in-memory compiled class hierarchy. Would extending Vertex in clojure automatically extend all subclasses?

10:08 angerman: tsdh: saw the example i just posted? — concerning the in memory complexity. Don't know if that has any impact at all. … just try?!

10:09 TobiasRaeder: And it seems to work on subclasses

10:09 (defprotocol Foo (foo [_]))

10:09 (extend-type Object Foo (foo [_] (println "abc")))

10:09 (foo (Object.)) -> "foo"

10:09 (foo (String. "")) -> "foo"

10:10 tsdh: TobiasRaeder: What if the String "foo" had already existed before the extend-type? (That's the case for me)

10:12 angerman: tsdh: seems to work as well.

10:12 stuartsierra: extend-type doesn't modify classes, it modifies the protocol. So it works on pre-existing types & objects.

10:13 tsdh: Yes, just checked it.

10:13 Nice.

10:13 stuartsierra: That kind of dispatch won't be as fast as in-line methods in a deftype or Java method definitions, but should still be faster than multimethods.

10:14 * angerman wonders if that behaviour (and approach) just feels more natural to those with ObjC (Smalltalk?) experience

10:14 tsdh: Another question. Why do defprotocols API docs have various *this* in the method sigs, but not the Protocols section on the clojure homepage.

10:14 angerman: tsdh: make it "self" and feel pythonic

10:14 stuartsierra: 'this' isn't a special symbol, just a convention borrowed from Java.

10:15 But every protocol method is required to have at least one argument, which is commonly called' this'.

10:16 dnolen: stuartsierra: 'won't be as fast' - the difference is negligible in my experience. dispatch via extend-type is still in billions of ops per second territory.

10:16 stuartsierra: Some early versions of the protocol API omitted the first "this" argument.

10:16 tsdh: stuartsierra: Ah, ok.

10:17 stuartsierra: cemerick: Come to think of it, where's the key?

10:17 tsdh: Well, then I'll see if protocols improve performance...

10:18 cemerick: stuartsierra: ~/.gnupg on build.clojure.org, last I knew

10:20 stuartsierra: got it. thanks.

10:25 tsdh: Hm, what's the error in http://pastebin.com/JnJ8YsBb ?

10:26 stuartsierra: tsdh: You have a call to the `iseq` protocol method with incorrect arguments somewhere.

10:28 tsdh: stuartsierra: Before, iseq was a defmulti dispatching on the class of the first arg. There, all tests passed (and of course no compile errors). Shouldn't the calls look identical?

10:30 stuartsierra: I don't think protocol methods can have variable arity.

10:30 Instead, define one protocol method with fixed arity, and a helper function to do default arguments.

10:33 tsdh: stuartsierra: My defprotocol was wrong. Different arities are given by: (iseq [this] [this cls] [this cls dir]), as the docs also indicate.

10:33 stuartsierra: ah, right.

10:34 tsdh: Hm, but now I get exceptions at runtime: java.lang.RuntimeException: java.lang.RuntimeException: java.lang.IllegalArgumentException: No distinct mapping found

10:34 gfrlog: is there any good way to handle a java dependecy with leiningen that is not in any maven repo that I can see?

10:35 apparently putting the jar in lib will add it to the classpath, but anything automated is preferred

10:35 tsdh: gfrlog: AFAIK, the answer is, make your own local maven repo. :-(

10:35 stuartsierra: gfrlog: You can install it locally, with mvn install:file

10:36 gfrlog: stuartsierra: okay, thanks

10:36 angerman: is there a cvs reader for clojure?

10:36 stuartsierra: lots, with varying degrees of bugs.

10:36 gfrlog: like the version control system? or the drug store?

10:37 stuartsierra: oh, I assumed csv

10:37 gfrlog: that's why I asked :)

10:46 (defn csv-parse [csv] (map #(s/split #"," %) (s/split #"\n" csv)))

10:47 stuartsierra: there are a surprising number of edge cases with CSV parsing.

10:47 gfrlog: stuartsierra: I would imagine so. Probably a lot of escapes, and you might want options to use the first row as a header and thus output maps

10:48 AWizzArd: gfrlog: https://github.com/davidsantiago/clojure-csv/blob/master/src/clojure_csv/core.clj

10:48 joly: especially with quotes and such, iirc

10:48 AWizzArd: This is a small 150-LOC parser/writer. It lacks lots of features.

10:51 gfrlog: but mine clearly does what I intended it to do :)

10:55 fliebel: neato! Calling addDirtyRegion multiple times gets collapsed into one repaint. Now I can just add that as the watcher for my ref.

11:00 semperos: happy friday

11:00 consbox: It seems that there is no way to read record from string even though there seems to be reader syntax for that (but create method is missing, clojure 1.2.1) ==> (defrecord Test [x]) (read-string (binding [*print-dup* true] (pr-str (Test. nil)))) ; any workaround?

11:00 gfrlog: semperos: likewise

11:01 wooby: consbox: work is being done on adding it, see http://dev.clojure.org/display/design/defrecord+improvements for ideas and details

11:04 fbru02: Hi guys i asked this before , does anyone know how to complie clojure source code (github.com/clojure/clojure) using eclipse or intellij ?

11:04 stuartsierra: fbru02: Current 1.3.0 alpha Clojure source supports building with either Ant or Maven.

11:05 fbru02: stuartsierra: thanks i will try it out

11:20 devn: good morning everyone

11:26 fliebel: good mornign devn

11:27 What happens when I assoc a record? Do I get a new one? Does it do structural sharing? I'm going to assoc it quite much, so it'd be unfortunate if I was creating thousands of huge objects.

11:33 devn: structural sharing fliebel

11:33 fliebel: devn: Thanks :)

11:34 devn: err fliebel sorry no

11:34 fliebel: you mean a defrecord?

11:34 fliebel: yea

11:34 * fliebel is going to kill the GC with his assoc'ing

11:34 devn: okay im going back and forth here -- but yes, i do believe they use structural sharing

11:34 http://stackoverflow.com/questions/4575170/where-should-i-use-defrecord-in-clojure

11:35 fliebel: right there they say 'no' again.

11:36 ah, and then 'yes' again

11:37 We'll see what the JVM thinks of my code...

11:38 If I run into trouble, I might use either regular maps(meh), or deftypes with mutable fields(meh)

11:39 devn: alex miller is generally very knowledgable and i dont know mikera but im inclined to believe that defrecord does do structural sharing

11:40 let me check one more resource for your quick

11:42 fliebel: im inclined to believe that you'll be fine performance-wise with defrecord

11:43 angerman: am I doing something wrong, if I think about performance tuning to come last?

11:43 devn: angerman: you're doing it right and wrong, simultaneously! :)

11:44 angerman: great

11:44 devn: angerman: reasonable attention to the problem you're going to be solving and recognizing some of the performance issues you may run into is a good thing to do before you commit to a solution

11:45 angerman: but in general you're going to want to "tune" last

11:45 that's my opinion

11:45 bbiab

11:47 angerman: devn: sure. The more complex your problem is and the broader your solutions space, a sensible heuristic (performance) may be a good guide finding a workable solution.

11:49 For me though, I've often had to deal with problems that consisted more of writing actual code then to choose from a large solution space. And I feel that a working solution is often more than good enough; rarely a perfect solution or a very near perfect solution is asked for.

11:50 devn: angerman: it all depends, and you seem to be aware of how muddy the water is around this particular topic

11:51 i can't really give an informed answer to your question without understanding the full context, problem, etc. which is more time than i have available unfortunately :)

11:51 best of luck, heading back to work... cheers!

11:51 angerman: lol

12:05 technomancy: is anyone submitting a clojure talk to oscon?

12:10 fliebel: Is there any way I can extend Fn to implement an abstract subclass of Runnable, or is a proxy the way to go here?

12:13 dnolen: fliebel: what subclass of Runnable?

12:13 fliebel: dnolen: java.util.TimerTask

12:14 So close, yet so far! The beauty of just passing a fn to Timer and make it work.

12:15 hiredman: ugh

12:15 don't use timertasks or timers

12:15 fliebel: hiredman: What else?

12:16 hiredman: http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ScheduledThreadPoolExecutor.html

12:16 fliebel: ah!

12:16 Just what I needed!

12:17 hiredman: Thanks a lot, you saved my life, or at least my sanity, or at least.. well thanks :)

12:17 hiredman: clojurebot: search for schedule

12:17 clojurebot: ping?

12:17 clojurebot: PONG!

12:18 hiredman: https://github.com/hiredman/clojurebot/blob/master/src/hiredman/schedule.clj

12:19 fliebel: hiredman: It says it does not use a bound threadpool, so setting that is not helping much in your code, I assume.

12:21 And I don;t think unit is used.

12:22 hiredman: fliebel: look at the example call at the bottom

12:24 fliebel: While this class inherits from ThreadPoolExecutor, a few of the inherited tuning methods are not useful for it. In particular, because it acts as a fixed-sized pool using corePoolSize threads and an unbounded queue, adjustments to maximumPoolSize have no useful effect.

12:24 fliebel: hiredman: Ah, it's called tu inside the function :)

12:24 hiredman: the constructor I call sets the corePoolSize

12:24 fliebel: hiredman: So that is just the maximum really?

12:25 okay, clear :)

12:28 hiredman: Why do you do proc+1?

12:29 hiredman: fliebel: no idea

13:28 fliebel: What model does Aleph use for concurrency? Threads or cooperative? Blocking or non blocking?

13:31 amalloy: LauJensen: someone asking clojureql stuff on SO, and from reading the cql source the behavior he sees doesn't make a lot of sense to me

13:32 haha nevermind, the second i pressed enter there the question got deleted

13:32 dnolen: fliebel: it's an async IO lib built on top of Netty.

13:33 fliebel: dnolen: Well, than I need to figure out how Netty works.

13:33 xkb: https://gist.github.com/887234

13:33 dnolen: fliebel: if you understand why people like node.js, you can understand what Netty is all about.

13:34 fliebel: dnolen: Well, I do, but I heard node is cooperative, so if you do heavy computations it just gets stuck. And I don't like nested callbacks very much.

13:35 I wrote some Twisted app, and then you go like "get this and then… oh, wait let me define another function somewhere"

13:37 dnolen: fliebel: Aleph recently added a async macro which allows you to write async code in a more natural way.

13:44 amalloy: dnolen: ztellman was really excited about his async macro when i met him at a meetup recently; i wasn't aware it was a part of aleph. do you happen to have a link to the macro in question?

13:48 dakrone: clojurebot: ~search for json

13:48 clojurebot: <#clojure:TimMc> http://hubpages.com/hub/Dont-use-XML-JSON-for-Clojure-only-persistence-messaging

13:48 <#clojure:paraseba> long live S-expressions ... no more json needed

13:48 <#clojure:brehaut> its no different to using json frinstance

13:48 <#clojure:TimMc> brehaut: https://github.com/joshua-choi/fnparse/wiki/Sample-JSON-parser

13:53 choffstein: Hey all. I have sort of an algorithm design question. I have a bunch of data that is date indexed. I want to create different groupings based on the first day of week definition. So if the first day is wednesday, I want to lump them into successive Wednesday-Tuesday groups. I've been playing around with group-by and Calendar to try to create a unique key based on the year and week-number, but unfortunately it messes

13:53 up when the week crosses over into a new year (obviously). If I use week-number alone, however, it won't work either because it will group weeks in different years. Any thoughts on an easy way to achieve this?

13:56 sritchie: choffstein: could you just use the starting day, and the period length?

13:57 ie, use the julian day calendar, and forget about weeks?

13:57 (after grouping, that is)

14:03 choffstein: ah, that might work

14:17 angerman: is there a maximum number of fields a record may have?

14:17 dnolen: angerman: if there is, I imagine it's a Java limit.

14:18 amalloy: yeah, clojure doesn't impose one

14:18 java has a limit on classfile size, but it's huge i think

14:19 angerman: weird...

14:20 adding a 9th field to the record, and I get NoSuchMethodErrors.. let's see if they persist after cleaning

14:20 amalloy: angerman: clojureql has a record with ten fields so that's certainly allowed

14:20 NSME is a versioning conflict

14:21 usually involving AOT

14:22 angerman: Hmm. After cleaning all classes and restarting swank, it works.

14:22 amalloy: LauJensen: since i was looking at cql, i saw that RTable.deref returns (fn [rs] (doall rs)) - is there a reason it doesn't just return doall?

14:25 fliebel: amalloy, dnolen: Has the async macro surfaced yet?

14:25 amalloy: fliebel: no; i'm hoping someone will be more excited about it than i am and do some googling

14:27 fliebel: I am: http://groups.google.com/group/aleph-lib/browse_thread/thread/28478c992cbb5555

14:34 https://github.com/ztellman/lamina/blob/master/src/lamina/core/expr.clj#L343

15:01 mec: Is there any difference between (amap a i _ (f (aget a i))) and (amap a i r (aset r i (f (aget a i))))

15:03 amalloy: &(doc amap)

15:03 sexpbot: ⟹ "Macro ([a idx ret expr]); Maps an expression across an array a, using an index named idx, and return value named ret, initialized to a clone of a, then setting each element of ret to the evaluation of expr, returning the new array ret."

15:03 xkb: hi

15:05 amalloy: &(seq (amap (into-array [1 2 3]) i _ (inc (aget a i))))

15:05 sexpbot: java.lang.Exception: Unable to resolve symbol: a in this context

15:06 mec: (let [a (long-array [0 1 2 3 4])] (= (seq (amap a i _ (inc (aget a i)))) (seq (amap a i r (aset r i (inc (aget a i)))))))

15:06 &(let [a (long-array [0 1 2 3 4])] (= (seq (amap a i _ (inc (aget a i)))) (seq (amap a i r (aset r i (inc (aget a i)))))))

15:06 sexpbot: ⟹ true

15:06 xkb: I'm still tinkering with my algorithm: I have a matrix nxn with contents per cell either 0 or 1. A 1 in a cell implies we can navigate from row y to row (column of 1). The algorithm should return all possible paths. Starting from cell [n-1,n-1]. I wrote something similar to this: https://gist.github.com/887234 (with recurs everywhere). This code however does not terminate.

15:06 amalloy: &(seq (let [a (into-array [1 2 3])] (amap i _ (inc (aget a i)))))

15:06 sexpbot: java.lang.IllegalArgumentException: Wrong number of args (5) passed to: core$amap

15:06 amalloy: blah whatever. anyway mec it looks the same to me but i don't use amap a lot

15:12 xkb: you don't mention what the "list" argument starts out as. i don't pretend to follow your algorithm, but setting "list" to (nth orgmat (count more)) looks bizarre out of context

15:13 xkb: amalloy: Ah, good remark. It starts with the bottom row of the matrix

15:13 amalloy: fwiw i also don't see why you use recur in most cases, and then not in the x=1 case

15:13 xkb: I will paste the non working algorithm

15:13 amalloy: bottom as in last?

15:13 xkb: this was just a test :)

15:13 yes

15:14 this is the code as is: https://gist.github.com/887415

15:15 It has become way more uglier than I started with, just trying to find out why it doesnt work

15:15 amalloy: you seem to be actually treating [7, 1]=1 as meaning row 7 can move to row 7, not row 1

15:15 (count more) will be 7 since there are 7 elements *left* in the list

15:15 xkb: ah yes, I reverse the list

15:16 amalloy: haha no offense but i'm going to murder you

15:16 xkb: cool :)

15:16 Now I'm hoping I dont live near you :)

15:16 maybe I should just step back to the intital problem

15:17 given the matrix, how would you calculate the paths

15:18 amalloy: ummmm, that depends on what you mean by "paths". you want to take this graph of direct connections and turn it into a graph of "nodes interconnected by paths of any length"?

15:18 xkb: btw this actually represents stacking boxes :)

15:19 My goal was to create lists of path's, e.g. [7 5 3 1] means from row 7 to 5 to 3 to 1

15:20 amalloy: i don't think you can do that in a tail-recursive way. you need a stack to keep track of where you are, no?

15:20 xkb: I starting to think that way as well

15:20 for the backtracking part

15:21 anyway, as of now, I cant even calculate one path :)

15:21 amalloy: have you looked at http://en.wikipedia.org/wiki/Transitive_closure

15:21 it may not be exactly what you want, but it's closely related and might be useful

15:22 xkb: interesting

15:22 the root problem is an ACM programming contest problem, known as Stacking Boxes. In imperative languages it is implemented using Dynamic programming

15:23 amalloy: dynamic programming just means "memoize except you have to implement it by hand every time"

15:24 xkb: indeed

15:24 so I started using memoize for the recursion parts

15:25 in my C# solution I use 2 arrays to keep track of the calc. history

15:26 much like this solution: http://chchwy.blogspot.com/2008/11/acm-103-stacking-boxes.html

15:27 stuartsierra: Clojure 1.2.1 staged to https://oss.sonatype.org/content/repositories/orgclojure-069/ - how's it look?

15:35 fliebel: Is there something like update-in for sets? Essentially it's just (conj (fn (disj key))), but there might be just a nice one somewhere that does this already.

15:36 s/disj/get/

15:36 sexpbot: <fliebel> Is there something like update-in for sets? Essentially it's just (conj (fn (get key))), but there might be just a nice one somewhere that does this already.

15:36 fliebel: no, wait… hmmm

15:36 (conj (disj key) (fn (get key)))

15:40 amalloy: fliebel: i don't think so

15:40 fliebel: amalloy: Okay, I'll craft my own, it's but a single line.

15:40 amalloy: in particular it wouldn't work if the thing you wanted to update to were already in the set? or at any rate it would behave oddly

15:41 hiredman: how so?

15:41 the thing you want to be in the set would be in the set

15:41 amalloy: hiredman: update-in would be decreasing the size of the set, which it never does for maps

15:42 &(let [s #{1 2 3} k 1] (conj (disj s k) (inc (get s k))))

15:42 sexpbot: ⟹ #{2 3}

15:42 amalloy: which seems "odd" by my lights, but it depends what fliebel wants it to do

15:43 fliebel: amalloy: It's not a proper update indeed, but I want to just take the value from a set, do something to it it and put it back.

15:44 hiredman: update-in is a transform on a map

15:44 getting a new map out with different properties is to be expected

15:45 the update-in-set thing would be a transform on a set, getting a new different set out seems like something that should be expected

15:45 fliebel: but… this is of no use…

15:46 Oh, maybe it is, let's just see how it works out...

15:50 ossareh: morning all

15:55 LauJensen: amalloy: Anything I need to respond to RE CQL ?

15:56 amalloy: LauJensen: nah, i think he was just blaming his problems on far-away code

15:56 though i do still wonder about the doall thing

15:56 fliebel: Oh, I'm sure there is some multimethod or extend-type to make java object print-friendly?

15:56 amalloy: $google amalloy hubpages xml json

15:56 sexpbot: First out of 4 results is: Don't use XML/JSON for Clojure-only persistence/messaging - HubPages

15:56 http://hubpages.com/hub/Dont-use-XML-JSON-for-Clojure-only-persistence-messaging

15:56 LauJensen: amalloy: okay

15:56 amalloy: fliebel: ^

15:57 (the stuff you want is at the end but it's not such a long article)

16:03 fliebel: amalloy: Can't get it to work :(

16:04 amalloy: fliebel: what is your goal? print a java object so that you can read it back in with (read-string)?

16:04 fliebel: amalloy: No, just stuff away all the crap it prints.

16:04 #<BufferedImage BufferedImage@77c30993: type = 5 ColorModel: #pixelBits = 24 numComponents = 3 color space = java.awt.color.ICC_ColorSpace@ed0f59e transparency = 1 has alpha = false isAlphaPre = false ByteInterleavedRaster: width = 215 height = 471 #numDataElements 3 dataOff[0] = 2>

16:04 amalloy: fliebel: it's calling foo.toString

16:05 fliebel: amalloy: I know, but can I do anything about that?

16:05 amalloy: i suspect that's hardcoded into the repl

16:06 what do you want to see instead?

16:07 fliebel: Just… something like <BuferedImage> probably with the width and height, I don;t care for the rest.

16:08 amalloy: i don't believe any such feature exists

16:09 fliebel: oh, I thought I had seen it, but it was probably print-dub. What does that do then, if not what I want?

16:11 TimMc: fliebel: Prints an eval-able representation.

16:12 amalloy: &(do (pr *ns*) (binding [*print-dup* true] (pr *ns)))

16:12 sexpbot: java.lang.Exception: Unable to resolve symbol: *ns in this context

16:12 amalloy: &(do (pr *ns*) (binding [*print-dup* true] (pr *ns*)))

16:12 sexpbot: ⟹ #<Namespace sandbox10597>#=(find-ns sandbox10597)nil

16:12 TimMc: You have to override the print-dup multimethod for most Java objects though.

16:36 dsantiago: I feel like there should be a clever function already around that takes a sequence of functions and an initial value as argument and applies all the funcitons in order, to the output of the previous one?

16:37 brehaut: (comp comp reverse) ?

16:37 ampleyfly: take a look at -> and ->>

16:37 if I understood you correctly

16:37 brehaut: bah no comp is varargs. ignore me

16:38 dsantiago: Ah, comp should do it, I can apply it.

16:38 ampleyfly: &(doc ->)

16:38 sexpbot: ⟹ "Macro ([x] [x form] [x form & more]); Threads the expr through the forms. Inserts x as the second item in the first form, making a list of it if it is not a list already. If there are more forms, inserts the first form as the second item in second form, etc."

16:39 dsantiago: ampleyfly, yeah, that's not quite what I want, because I don't have the list of functions in hand.

16:39 ampleyfly: ah

16:39 brehaut: (comp (partial apply comp) reverse) is what i ment

16:41 dsantiago: brehaut, yes, thanks. That's perfect.

16:41 These things are never named any of the things I try searching the docs for.

16:41 Caffeine: Is there a way en emphasize that a global value is a constant? I know usually global values are between * .. and I know the macro trick to kinda make C #defines, but well yeah, anything else? convention? Being principally a Java programmer I'd write them in caps.. and btwn * maybe

16:41 ampleyfly: brehaut: that's cool

16:41 technomancy: Caffeine: emphasizing that something is constant means implying other things aren't.

16:41 Caffeine: haha

16:41 seen that way

16:42 okay.. you're right... then you just hope someone doesn't use set! on it I guess :)

16:42 technomancy: we're all big kids here

16:48 ossareh: &(= [] '())

16:48 sexpbot: ⟹ true

16:48 ossareh: suprising to anyone?

16:49 dnolen: ossareh: why should that be surprising?

16:49 ,(= [1 2 3] '(1 2 3))

16:49 clojurebot: true

16:49 brehaut: ossareh: collections are compared based on the interface they support rather than the concrete type

16:49 ossareh: dnolen: a nice surprise, btw.

16:50 brehaut: aha, I like that.

16:50 brehaut: ,(= (array-map :a 1) (hash-map :a 1))

16:50 clojurebot: true

16:50 fliebel: Do any of the big O's know what is the fastest way to detect collisions? It seems to me that you almost need to compare every object to every object, but I'm sure you can do some smart elimination.

16:50 dnolen: ossareh: in the presence of lazy sequences it seems like the only reasonable behavior, otherwise you pay for conversions.

16:51 stuartsierra: Any ideas while compiling the Clojure tests would throw java.lang.ClassCastException: clojure.test_clojure.genclass.examples$loading__4293__auto__ cannot be cast to clojure.lang.IFn, compiling:(examples.clj:9) ?

16:51 s/while/why/

16:51 sexpbot: <stuartsierra> Any ideas why compiling the Clojure tests would throw java.lang.ClassCastException: clojure.test_clojure.genclass.examples$loading__4293__auto__ cannot be cast to clojure.lang.IFn, compiling:(examples.clj:9) ?

16:52 dnolen: fliebel: are you talking about collisions in a collection?

16:52 fliebel: dnolen: no, the game type of stuff.

16:52 overlapping bounding boxes.

16:53 hiredman: sounds like an abi mismatch, new clojure with older classfiles sitting around or similar

16:53 stuartsierra: hiredman: possibly, but Clojure is what I'm building. :)

16:53 brehaut: fliebel: buckets of geometry math and 2D or 3D tree structures let you eliminate tests

16:54 fliebel: brehaut: Okay, sounds good, do you have any terms I can google for?

16:55 hiredman: stuartsierra: do you start with a clean tree? like clear out target or classes or whatever

16:55 stuartsierra: yeah

16:55 brehaut: RTree, QuadTree, Octree, bsp tree

16:56 hiredman: seems likely it could be something with the lazy var->fn loading

16:56 but that went in weeks ago

16:57 brehaut: fliebel: im not a game programmer, but ive done stuff with mapping so i might be a bit off with actual game structures, but those should give you an idea of where to go

16:57 danbell: hey, anyone know how to parameterize a SQL statement with multiple parameters in contrib.sql?

16:57 fliebel: brehaut: Thanks :)

16:57 danbell: nm, I think I got it

17:01 tsdh: Can anyone tell me what this exception means? http://pastebin.com/DupydhJy

17:02 stuartsierra: tsdh: maybe a Protocol method invocation with multiple possible implementations?

17:04 tsdh: stuartsierra: You mean, I might have implemented a foo method for A, B, and C, where B implements A and B, and now a method was called for a B instance?

17:04 stuartsierra: yep

17:05 tsdh: Hm, I'll check. The real strange thing is that if I run the form the testmacro executes in the REPL, it works fine.

17:06 hiredman: restart your repl

17:06 stuartsierra: tsdh: it might depend on which namespaces you have loaded at the time.

17:06 tsdh: hiredman: That doesn't change anything.

17:07 hiredman: clear ./classes and restart your repl

17:08 tsdh: Ok, I'll do so.

17:12 hiredman: Oh, great. Now I get the same error at the repl. ;-)

17:17 amalloy: tsdh: i think that may have been his goal. now you've confirmed your code is buggy and don't have to worry about stale classes in the repl or otherwise

17:18 tsdh: amalloy: Yes, I know. But after adding a (println "foo") in the function just before the line that was the error position in my code, C-c C-k to recompile, bang!, it works again at the repl.

17:24 Now I quit the repl, did lein clean again, lein swank, new repl, and this time it works instantly...

17:32 Hm, now the testcase that always errored runs fine, and another one errors. The first place of my own code in the backtrace is my defprotocol...

17:32 stuartsierra: sounds like an order-of-loading issue

17:34 tsdh: And how do I find out what's the right order? And how do I affect the order?

17:34 stuartsierra: you shouldn't have to control the order.

17:35 If the behavior of the code is different depending on what is loaded when, you've got a bug.

17:37 hugod: tsdh - I always require the defining namespace wherever I import the protocol, and never use :reload or :reload-all int he tests

17:37 stuartsierra: :reload or :reload-all in a `(ns…)` is always wrong.

17:38 tsdh: Oh, I'll remove that. I had it there, cause lein new added it automatically

17:38 stuartsierra: yes, that's a bug.

17:38 technomancy: fixed in 1.5.0; time to upgrade.

17:38 stuartsierra: good to hear

17:40 tsdh: Running lein upgrade now. ;-)

17:41 technomancy: it would have been fixed sooner except there's no way to do :reload with load-file, so there's some heinous monkeypatching in swank-clojure to work around that.

17:41 tsdh: But anyway, removing :reload and any AOT and gen-class doesn't help either.

17:41 hugod: the effects of reloading namespaces, at the repl or with :reload, seems to get everyone the first time they use protocols

17:43 tsdh: hugod: You said, I should require the namespace defining the protocols. Now I see that I :use it. Is that wrong?

17:43 stuartsierra: that shouldn't matter

17:44 hugod: tsdh: use or require should work

17:44 tsdh: ok

17:48 fliebel: Yay! My "game" is working! http://yfrog.com/ny71230492p

17:48 stuartsierra: cool

17:52 groovy2shoes: fliebel: w00t!

17:55 * fliebel realizes his game has no frames, you just tell swing what has changed all the time, and it'll decide to repaint sometime.

17:56 Raynes: brehaut: Ping.

18:03 brehaut: Raynes: pong

18:03 Raynes: brehaut: I'm sure you've told me this before, but why is fault a record?

18:04 brehaut: i cant actually remember off the top of my head!

18:04 Raynes: Hehe.

18:05 stuartsierra: w00t! Got Clojure to build all the way with my new plugin!

18:05 brehaut: i think i wanted a concrete type to make it distinct from real values that are returned; there is a fault? predicate to test for its presence, and the attempt-all (average name) that also uses that

18:06 Raynes: brehaut: It's actually okay, since I can just check the type to see if something went wrong.

18:06 For the record, it seems to be working just fine.

18:06 stuartsierra: https://github.com/stuartsierra/new-clojure-maven-plugin

18:06 brehaut: Raynes: from the client RPC function?

18:07 Raynes: I didn't catch a question.

18:08 brehaut: Raynes: checking for a fault response from the 'call' function

18:08 Raynes: Yes, because in this case, it means "Yo, you gave me wrong credentials. I'm sad now."

18:10 brehaut: Raynes: were you expecting it to be an exception?

18:10 Raynes: No.

18:10 I would have expected it to be a map with a :fault? key. I haven't used much code that uses records.

18:10 Nor written much.

18:11 And by much, I mean any.

18:15 brehaut: Raynes: there is also potential that 'corrupted by haskell' is part of the reason

18:15 Raynes: :p

18:20 brehaut: (= (type blogs) necessary-evil.fault.Fault)

18:20 brehaut: Raynes: necessary-evil.fault/fault?

18:21 Raynes: orly

18:21 I didn't want to import anything.

18:22 brehaut: whys that?

18:23 Raynes: Because I plan to have no less than 600 lines of Swing imports before I'm finished. But this is much prettier, so I'll make an exception.

18:23 brehaut: oh yeah swing. :S

18:23 you also want to look at attempt-all in the same namespace

18:23 its like let that is fault aware

18:26 Raynes: an example https://github.com/brehaut/clj-pingback/blob/master/src/clj_pingback/server.clj#L68-83

18:26 Raynes: Cool.

19:32 JanPalencar: Hi guys, anybody experienced strange kind of behaviour with compojue 0.4.0, ring 0.2.0, when routing to .... (file "filename"). After some time Jetty says, IAE: No method in multimethod 'render' for dispatch value: class java.io.File. Perhaps run out of file handles?

19:33 brehaut: JanPalencar: those are really old versions of ring and compojure; are you following an old tutorial?

19:33 JanPalencar: @brehaut, i tried to stick to stable RCs

19:35 brehaut: i was not aware that either project claimed that those versions were stable

19:36 JanPalencar: perhaps try [ring/ring-core "0.3.7"] and [compojure "0.6.2"]

19:36 oh make that [ring "0.3.7"]

19:37 JanPalencar: @brehaut I know they are older, well what i did is that i replaced file with slurp

19:37 everything went fine from that point on

19:41 @brehaut sorry i used RC2, didnt meant it was stable

19:46 p_l|home: are there any nice libraries for working with RMI in Clojure?

19:51 JanPalencar: @brehaut Do you know about uptodate API docs for the 0.6.2 compojure ?

19:52 brehaut: JanPalencar http://weavejester.github.com/compojure/ ?

19:54 JanPalencar: @brehaut More than half of the links are broken in API docs

19:54 brehaut: perhaps try #compojure

19:55 i dont use compojure myself

19:55 i only know bits and pieces from reading the source

19:58 JanPalencar: @brehaut

19:58 thanks

19:58 bbye

19:59 brehaut: no problem

20:10 amalloy: @brehaut so cute when twitter leaks into irc

20:10 hiredman: :(

20:10 amalloy: hiredman: take heart, i don't actually approve

20:13 brehaut: @amalloy: haha #notreally

20:13 * amalloy isn't enough of a twitter hipster to have thought of #notreally

20:14 brehaut: i really dislike hashtags

20:14 amalloy: they're meh

20:15 i find it hard to imagine feeling strongly about them

20:16 brehaut: i skim my twitter thing and hashtags are grey rather than black. people put their actual message into hash tags way too often and i miss it thus get confused later on

20:17 hiredman: hashtags often say important things like #notserious

20:17 #justkidding

20:17 technomancy: #totallylying

20:17 hiredman: etc

20:23 TimMc: Meh, I used @-addressing *before* it was popularized by twitter, #backwhenitwasonvinyl

20:23 amalloy: TimMc: #backinmyday we called it email

20:25 TimMc: Oh hey, I didn't even think of that.

20:26 I used a format like "@amalloy: You're wrong." in blog commenting and such. Now I feel stupid when I use it. :-(

21:04 ngw: guys, I know nothing about java, so please bear with me

21:05 I keep looking at some projects and I'm baffled by the file structure

21:05 like src/clj/http/async

21:06 it seems something that comes from java, but I might be wrong

21:06 is there some naming 'general rule' that I am missing ?

21:06 most of those directories are empty, so I don't really see why someone would want to adopt a structure like that ...

21:13 nobody ?

21:13 a link is fine, I can read :p

21:15 ataggart: java packages are represented in the file system as a hierarchy of directories

21:16 the src/clj is the root directory for clojure source, as opposed to src/java for java source, etc.

21:16 hiredman: only if you are using the clojure maven plugin

21:17 technomancy: actually I think in this case the project is called clj-http, so src/ is the source root

21:17 ngw: leinigen puts a core.clj under src/project

21:17 hiredman: other clojure build tools omit the langauge part of the path, because you are building clojure

21:17 ngw: I see

21:17 thank you

21:19 technomancy: ngw: short version is if you did src/foo.clj, it would go into Java's "default package" which is a no-mans land from which code can't always be loaded consistently

21:19 so there's a convention to put it at least one throwaway directory deep.

21:19 also many Java programmers get paid a commission on a per-directory rate.

21:24 ataggart: Assuming one had the power to change field values on JIRA tickets, where would one find those actions in the UI?

21:25 amalloy: technomancy: i can confirm that when i last wrote java, my classes were in com.mycompany.cassandra.mapreduce.myproject.hadoop.* or something

21:26 technomancy: amalloy: bonus!

21:26 amalloy: technomancy: i get points for the confused notion of how cassandra and hadoop fit together?

21:27 technomancy: sure. even more if it's nested in maven's modules/src/java/main goop.

21:27 hiredman: com.company.southeastasia.factory.automation.ConfigurationFactoryFactoryStrategy

21:28 amalloy: technomancy: sorry, i stay away from maven if i don't have cake/lein as a buffer

21:28 technomancy: also helps justify purchase orders for widescreen monitors

21:28 amalloy: technomancy: i prefer to order expensive word-wrapping software

21:29 hiredman: deviant

21:31 ngw: I waited a bit to answer because I wasn't sure the per-directory commission basis was a joke

21:32 I didn't want to offend anyone :)

21:32 (it's a joke, right ?)

21:32 amalloy: technomancy: your joke was more of a flop than you thought

21:32 ngw: lol

21:33 hiredman: joke?

21:33 clojurebot: Oh, I know the best knock-knock joke! It goes like this... OK, you go first:

21:33 technomancy: amalloy: great, I'll have to stick to my old tried and true HTTP status code burns.

21:34 amalloy: technomancy: 100

21:34 hiredman: zing!

21:34 technomancy: dang; he called my bluff

21:34 501

21:35 amalloy: ngw: anyway, java loves really-deep package names to make sure they're globally unique even if your evil clone in an alternate universe is working on a project to do the same thing

21:35 ngw: thanks amalloy, I got it now

21:35 technomancy: amalloy: good point; better move all my directories to src/earth-616/technomancy

21:35 ngw: I don't think I will conform to this practice honestly :)

21:36 amalloy: ngw: clojure doesn't like them that deep

21:36 just src/myproject/{core,utils,whatever}.clj

21:36 hiredman: ngw: it's ok, I doubt I'll ever use code you write, so do whatever you want

21:37 ngw: I wouldn't use the code I write as well, I understand

21:37 :p

21:38 hiredman: deviation from the norm is not to be recommended unless you understand the norm, and are familiar with the ins and outs of it

21:39 the first thing anyone will say if you ask for help is "this code is in a weird style, rewrite it in the accepted style so I can follow it"

21:41 ngw: compojure uses the same style

21:41 hiredman: what style?

21:41 ngw: src/project/*.clj

21:41 where project is compojure

21:41 hiredman: that is the accepted style

21:41 amalloy: ngw: indeed, there's a reason it's called conventional/standard

21:41 hiredman: it isn't project

21:41 ngw: oh fantastic

21:42 hiredman: it just happens that most projects use the name of the project as the first segment of the namespace

21:42 ngw: no I was asking about deeper structures, that's what I don't like / understand

21:42 hiredman: clojurebot: okay is pokau

21:42 clojurebot: Ok.

21:42 hiredman: clojurebot: pokau is okay

21:42 clojurebot: Ok.

21:43 amalloy: ngw: deeper structures are used when you have "too many" files to shove all in the top level of your project, or some of them naturally seem grouped together

21:43 hiredman: the deeper structures are generally the result of people refusing to give up their death grip on maven

21:44 amalloy: hiredman: i assumed he meant src/myproject/communication/{write,read}.clj or what have you. you're not saying that's a maven symptom, are you?

21:44 hiredman: people who do things like drop a java source file in there for no real reason

21:44 amalloy: could be, a lot of things are

21:45 ngw: I was looking at https://github.com/neotyk/http.async.client/

21:48 * amalloy has core.clj at ~/src/clojure/src/clojure/src/clj/clojure/core.clj

21:48 amalloy: not exactly an inspiring example

21:49 ngw: that's why I asked, it didn't seem right

21:49 but it's a lib I'm using, so ...

21:51 ataggart: Anyone present able to modify a CLJ ticket's field values in jira?

21:54 dnolen: shot in the dark, anybody ever look at the Threads Yield Continuations paper?

21:59 amalloy: dnolen: no, but i remember seeing something on twitter a month or two ago called, maybe, "call/cc? i yield!"

21:59 which sounds like it'd probably at least be interesting to you

22:04 dnolen: amalloy: hmm interesting, thanks, but not quite what I was looking for. I was curious about about the performance profile of the implementation in Threads Yield Continuations paper with respect to the JVM.

23:14 Caffeine: Any data structure with quick indexed access? I need to make a ± big 2D table with indexed access.

23:17 tomoj: ±?

23:18 vector access by index is O(log_32(n))

23:22 Caffeine: about 5000 x 5000

23:22 ok, good

23:22 thanks

23:49 amalloy: tomoj: i choose to believe that log32(n) === 1

23:50 tomoj: sure

23:50 gregh: I choose to live in a 32-dimensional world

23:50 tomoj: but since O-notation is really about asymptotics it seems wrong to say O(1)

23:52 p_l|home: tomoj: except it feels right when you think of "constant function"

23:53 tomoj: huh

23:56 p_l|home: tomoj: technically, O-notation is a case of two functions, O(X), where O is a constant function representing worst-case cost, which multiplies the result of function X. '1' is basically "X is a constant function".

23:57 Or at least that's what my barely churning, forced to work with Java and RMI brain dug out from memory.

23:57 technomancy: http://p.hagelb.org/oscon-clojure.org.html feedback welcome

23:58 tomoj: p_l|home: what you say makes little sense to me

23:58 but my brain, though thankfully not forced to work with java, is soaked in alcohol

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