←2007-09-16 2007-09-17 2007-09-18→ ↑2007 ↑all
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02:32:19 <edwardk> anyone awake who is versed in haskell syntax? playing with a toy language with similar syntax at the moment
02:32:32 <pikhq> oerjan? Oh oerjan?
02:32:34 <oerjan> *ahem*
02:32:39 <edwardk> but with no types
02:32:41 <edwardk> heya oerjan
02:33:23 <edwardk> basically i figured out a way to code up monads without types, so i've been playing with a framework somewhat between haskell and erlang for the last few days
02:34:06 <edwardk> ever used erlang?
02:34:37 <oerjan> nope
02:34:41 <edwardk> the idea in erlang is that you have atoms lists and tuples, and a few primitive types, but nothing else really and no type system.
02:35:30 <edwardk> what i went back and did was revisit the notion of a constructor in a typeless setting, so now i just say that a given constructor has some 'arity' associated with it. i.e. cons has arity 2 and nil has arity 0, but avoid specifying the types of the terms that go in each slot.
02:36:01 <oerjan> ok. similar to prolog i guess.
02:36:16 <edwardk> so in erlang you'd have to say {cons, x, xs} or {nil} whereas in this setting you can say arity 2 Cons, then Cons x xs and the default arity is 0
02:36:29 <edwardk> sorta, except it can be written applicatively because of the basic lazy semantics
02:36:30 <oerjan> (i vaguely recall erlang being descended somewhat from prolog, btw)
02:36:53 <edwardk> so you get haskell style pointfree syntax
02:37:27 <oerjan> yeah
02:37:31 <edwardk> so the dilemma comes about with monads, right since traditionally you think of a monad as doing different things based on the type it is inhabiting
02:38:15 <oerjan> pretty essential if you want more than one with the same syntax
02:38:15 <edwardk> so if you don't have types, haskell style monads seem like they are right out without passing around some sort of additional parameter that indicates the 'type of monad you are in' and using that. i.e. the haskell dictionary passing style
02:38:26 <edwardk> well, turns out you don't need that after all =)
02:38:46 <edwardk> the trick is the monad laws
02:38:59 <oerjan> i have thought similar thoughts
02:39:16 <edwardk> so for a concrete example lets define the identity monad
02:39:17 <edwardk> return = Ok
02:39:21 <edwardk> Ok x >>= f = f x
02:39:39 <edwardk> now Ok is a constructor which can be used as a tag when pattern matching on >>= so it knows what case its in.
02:39:45 <edwardk> mzero = Nil
02:39:50 <edwardk> Nil >>= f = f x
02:39:51 <edwardk> er
02:39:55 <edwardk> Nil >>= f = Nil
02:40:07 <edwardk> ok, so now we have the Identity Monad, and a Maybe monad
02:40:29 <edwardk> but what we need to do is anticipate that anywhere we could use the resulting monad we could also get 'Ok'
02:40:41 <edwardk> runReader (Reader f) = f
02:40:46 <edwardk> runReader (Ok x) = const x
02:41:19 <edwardk> so, then we consider something like 'ask' which seems to behave differently depending on context.
02:41:23 <edwardk> ask = Reader id
02:41:24 <oerjan> yep, you need a return that can be used everywhere. same solution as i thought of.
02:41:49 <edwardk> so the trick there is to autolift that into the reader transformer
02:41:49 <oerjan> there is some limitation though.
02:42:17 <edwardk> there are, in that you always have to tag it with a constructor
02:42:18 <oerjan> you can only use this for monads where >>= is strict in the first argument.
02:42:23 <edwardk> there is no 'true identity monad'
02:42:27 <edwardk> that is also true
02:42:35 <oerjan> Reader is not really
02:42:39 <edwardk> at least strict insofar as the outermost tag
02:43:28 <oerjan> otoh if you use something like runReader, maybe you can avoid that.
02:43:35 <edwardk> yeah
02:43:38 <edwardk> so the other fix
02:44:01 <edwardk> was to do something like the solution i want to play with for how to handle the monomorphism restriction and numerical classes
02:44:11 <edwardk> which reverts to carrying around the type parameter
02:44:41 <edwardk> if we define : to be an infix function, and + to be an arity 2 constructor you can say things like
02:44:59 <edwardk> a + b : Int = mp_add (a : Int) (b : Int)
02:45:21 <oerjan> haskell uses ::
02:45:22 <edwardk> and so on and so forth as a way to define how to recursively evaluate an expression as an integer
02:45:39 <edwardk> yeah the : in that case is an actual operator in my toy language. and i never liked haskell's :: =)
02:45:49 <oerjan> ML uses :
02:45:51 <edwardk> yeah
02:45:56 <oerjan> and the opposite for lists
02:46:09 <edwardk> i'm : for 'types' in this case and ; for lists
02:46:45 <edwardk> so with that same machinery you can make 'Return' and >>= both into constructors and define a similar decomposition
02:47:10 <edwardk> Return x : List = (x; Nil)
02:47:49 <edwardk> m >>= k : List = concat (map k m)
02:48:23 <edwardk> then the same expression consisting of Returns and >>='s can be reused in different monads until you apply a : to 'type' it
02:48:46 <edwardk> there are some tricks that still entails because : T should be idempotent, etc.
02:48:58 <oerjan> didn't you play around with a language with lots of types and (partially undecidable) inference a while ago?
02:49:03 <edwardk> and basically all : T is doing it taking the place of runT
02:49:34 <edwardk> yeah this is the same language i just stripped out the types for a while, since the non-type aspects (the substructural annotations and the theorem proving parts) are the parts I care about
02:49:55 <edwardk> so i wanted to see how far i could go with no types in the traditional sense, just detected pattern match failure
02:49:56 <oerjan> oh
02:50:08 <edwardk> basically its if i use ndm's CATCH tool as my type system ;)
02:50:25 <edwardk> or ESC/Haskell without the /Haskell =)
02:50:59 <edwardk> i figured it was a much stronger result to be able to duplicate existing techniques with the machinery than to just layer another abstraction on top
02:51:17 <oerjan> ic
02:51:57 <edwardk> otherwise the language remains unchanged, optimistic evaluation with lazy semantics, still has the theorem proving bits, but none of those pesky types
02:52:17 <edwardk> having the monads above lets me stay lazy and not go crazy
02:52:52 <edwardk> constructor elimination becomes of course a critical optimization step because EVERYTHING is tagged and constructors are global
02:53:11 <edwardk> so my apply/dispatch mechanism is uglier
02:53:44 <edwardk> and as a result of the above reasoning its necessary for me to allow extension of the same function (say >>=) in many locations in the code
02:53:57 <edwardk> so its hard to do separate compilation
02:54:01 <edwardk> but its a fun mental puzzle
02:54:06 <oerjan> "We're all mad here. I'm mad, you're mad." "How do you know i'm mad?" Said Alice. "You must be." Said the Cat, "or you wouldn't have come here."
02:54:26 <oerjan> (regarding going crazy ;) )
02:54:51 <edwardk> =)
02:56:11 <edwardk> http://comonad.com/r5.opt
02:56:19 <edwardk> is sort of a spew of random gibberings in this setting
02:57:23 <edwardk> arity declarations are kind of like haskell fixity declarations, but for right now fixities are er. fixed coz i'm lazy and haven't added them =)
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02:57:49 <edwardk> \x. foo ~= \x -> foo since there is no legal use for a . inside a pattern there
02:57:58 <edwardk> and its closer to the lambda calculus formalism
02:58:58 <edwardk> i like the fact that it sort of naturally subtypes back and forth between the monads (Nil and Nothing collapse, etc)
02:59:12 <edwardk> the Identity monad is just a Maybe monad where Nil is never used, etc.
02:59:36 <edwardk> i had an earlier version with "types" for the monads before i realized i could live without the type tags
03:00:40 <edwardk> http://comonad.com/r3.opt
03:01:45 <edwardk> basically anything without a = in the line is taken to be an 'axiom' which is just a function that any time the pattern matches returns true, and if none of the patterns match anywhere it returns false
03:02:03 <edwardk> and i do prolog/erlang style structural equality tests if you use the same term in a pattern twice
03:02:06 <edwardk> x <: x
03:02:09 <edwardk> for instance
03:03:45 <oerjan> hm... you get sort of a supermonad that includes all the others...
03:03:51 <edwardk> but plumbing around the monad type everywhere got ugly, i did a version with a sort of implicit type-level reader monad and another draft using dynamic binding and delimited control to change a dynamically scoped 'current monad' variable with pattern matching support on dynamic variables
03:03:53 <edwardk> yeah
03:04:16 <edwardk> brings to mind that somewhat horrid 'unimo' paper iirc
03:04:52 <edwardk> but basically i find it amusing that it lets me express a subtyping relationship among the different monads thats more or less impossible to express in a hindley milner style formalism
03:06:02 <edwardk> i started down this slippery slope with http://comonad.com/reader/2007/parameterized-monads-in-haskell/
03:06:35 <edwardk> one thing i like about it is the reductions are confluent even if you are locally working in a different 'sub-monad'
03:07:09 <edwardk> i.e. if you work with just returns and >>= you stay in 'identity' until you mix in an 'ask' then you get lifted out into Reader, then maybe you 'get' so you get placed in a state monad, etc.
03:07:23 <edwardk> then when you runFoo you peel off the layers of the onion
03:07:31 <edwardk> and you coerce the types to fit
03:08:02 <edwardk> so locally you can avoid having to pay the overhead of the full monad you are in
03:09:19 <edwardk> which when you add in constructor-elimination should open up a lot of optimization opportunities that you never get exposed to in haskell because you can't see them through the monad-noise
03:10:09 <edwardk> the pain in the ass comes from the fact that i have to try to use control flow analysis to see if you ever do the wrong thing ;)
03:11:39 <edwardk> still playing with it
03:11:48 <edwardk> but i thought it was a neat way to tackle the 'untyped monad'
03:12:09 <edwardk> as opposed to the dictionary passing style mechanism that dpiponi used in his toy untyped monadic language
03:12:40 <edwardk> coz passing dictionaries everywhere explicitly gets rid of the nice syntactic benefits of having monads
03:21:37 <oerjan> i guess a mathematician if necessary would put the monad as index on the >>=
03:22:26 <edwardk> i played with carrying around an explicit type using the : as a reduction operator, which lets you do things like the anonymous reader monad as well
03:22:36 <edwardk> not sure if thats a win though
03:23:00 <edwardk> the : reduction technique is how i'm thinking about handling the monomorphism restriction though
03:23:05 <edwardk> its a funny way to view the world though
03:23:09 <edwardk> + as a constructor
03:23:26 <edwardk> then applying an evaluation function (:) to the constructed value the evaluate it
03:24:36 <oerjan> your mixing of monads might be a bit awkward if the transformers don't commute
03:24:48 <edwardk> yeah a known issue =/
03:25:19 <edwardk> you may have to inject a runFoo or a : t to disambiguate
03:27:06 <edwardk> x : READER = Reader (runReader x)
03:27:33 <edwardk> so that its idempotent
03:28:04 <edwardk> then i can stick to my 'typeless monad' approach and use (:) as a disambiguation operator letting it retain its 'type-annotation' like connotation
03:51:22 <bsmntbombdood> f(15) = 16; f(34) = 92; f(13) = 8; f(20) = ???
03:52:30 <oerjan> huh?
03:52:57 <oerjan> is this all the information about f you've got?
03:54:16 <oerjan> 13 is a prime, and 8 is the previous fibonacci number
03:54:27 <bsmntbombdood> that's all the information i have
03:54:41 <edwardk> ah one sec
03:54:48 <edwardk> just looked at my screen i think i know it
03:54:56 <bsmntbombdood> oh, edwardk
03:55:14 <bsmntbombdood> you were the one with the language that no one but oerjan understood, right?
03:55:51 <edwardk> > let f x = x*4 - 44 in map f [15,34,13,20] ===> (10:55:49 PM) Lambda Bot: [16,92,8,36]
03:56:01 <edwardk> yeah
03:56:38 <edwardk> its changed into a simpler language with basically the same issue ;)
03:56:58 <oerjan> :D
03:57:32 <edwardk> bsmntbombdood: anyways that should answer your question
03:58:03 <edwardk> the key insight for me was the f(15) and f(13), i backed that out to guess f(11) and used f(34) to test its linearity
03:58:31 <bsmntbombdood> aaah
04:00:35 <oerjan> exercise: now, if it hadn't been linear, why wouldn't it be a good idea to try a second degree polynomial? ;)
04:00:51 <edwardk> heh
04:01:11 <edwardk> coz you could always find one? =)
04:01:21 <oerjan> edwardk wins the prize!
04:01:32 <edwardk> i knew that math degree was good for something ;)
04:02:11 <edwardk> actually thats a perfectly good use for a second degree polynomial for these silly underspecified problems =P
04:03:13 <oerjan> probably
04:03:15 <bsmntbombdood> what about f(361) = 22; f(121) = 14; f(81) = 12; f(25) = ??
04:03:31 * edwardk watches as #esoteric does bsmntbombdood's homework =)
04:03:42 <bsmntbombdood> not my homework!
04:03:50 <bsmntbombdood> (my dads) :P
04:04:02 <edwardk> look at f(121) and f(81), do the same trick i did above
04:04:05 <oerjan> in this case we are looking at squares
04:04:15 <edwardk> oerjan: ?
04:04:45 <oerjan> all the arguments are squares
04:04:46 <edwardk> 'every 20 it changes by 1', so find 0
04:05:07 <edwardk> rise over run
04:05:10 <oerjan> sqrt(n)+3
04:05:21 <oerjan> in fact
04:05:57 <edwardk> i'll buy that
04:06:45 <bsmntbombdood> wow
04:06:46 <bsmntbombdood> thanks
04:10:40 <edwardk> oerjan is right in that case since that one fails the naive linearity test: > let f x = x/20 + 7.95 in map f [81,121,361,25] ==> Lambda Bot: [12.0,14.0,> 26.0 < ,9.2]
04:11:08 <edwardk> and it looks ugly when you try it linearly ;)
04:13:05 <edwardk> so do you think people would like to play with a (sort-of) untyped lazy language with just constructors and easily extensible cases? it opens up a haskell-like language to the erlang-like use cases of long-uptime systems, etc.
04:13:22 <edwardk> since its easy to code-swap in that sort of system
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06:20:41 <pikhq> Just a tiny game I've been designing in PEBBLE. . .
06:20:54 <pikhq> (PEBBLE being a macro language I devised which compiles to Brainfuck)
06:21:16 <Guilt> oh? :)
06:21:18 <pikhq> http://pikhq.nonlogic.org/pebble.php If you need to ask me questions, do so later; I'm going to bed, since it's late.
06:21:27 <pikhq> Sorry.
06:21:32 <Guilt> okay :) nighty night
06:21:35 <bsmntbombdood> getting up early--
06:21:36 <pikhq> Enjoy Brainfucking with everyone else. . .
06:21:40 <pikhq> If they're here.
06:21:54 <Guilt> i will! :)
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08:12:55 <Guilt> i was wondering. would the equivalent of code-compression in brainfuck involve functions? :)
08:13:12 <Guilt> brainfuck code is kinda' huge
08:16:41 <Guilt> brainfuck code looks easy to compress, you know.
08:17:01 <Guilt> with lz, you could put those identified patterns together
08:24:07 <lament> yes, it's easy to compress.
08:24:23 <lament> try bzip2 :)
08:25:42 <Guilt> lament: no, at executable code level.
08:25:56 <Guilt> upxing gave me a 14% compression thing.
08:26:10 <Guilt> 14% of uncompressed executable data
08:26:36 <Guilt> i was wondering if anybody tried doing code compression. :)
08:26:47 <Guilt> so you can also identify reusable brainfuck patterns
08:26:52 <Guilt> like a library of sorts.
08:27:15 <Guilt> hmm. the next best thing: a portable brainfuck library :D
08:27:17 <Guilt> hehe
08:27:18 <lament> i'm not sure whether "at executable code level" is meaningful.
08:27:38 <lament> there're several macro preprocessors for brainfuck, though.
08:27:42 <Guilt> lament: http://guilt.bafsoft.net/downloads/wip/Brainfuck.tar.bz2 check this out.
08:28:02 <Guilt> LostKng.b compiled to an executable of size 2 odd megs.
08:28:12 <lament> oh, i see
08:28:53 <Guilt> you know, which is why i wondered if there would be a way to reduce code.
08:29:05 <Guilt> like combining a compiler with a compressor. ;) lol
08:29:08 <lament> yes, of course.
08:30:15 <Guilt> hmm. one easy way to partition it is to take loops which lead to the same text pattern. make them functions with labels. call them instead of jumping to them, and return back.
08:30:37 <Guilt> that way you could save considerable space.
08:30:55 <Guilt> you're not passing any data through the stack, which makes it a little slower, but smaller
08:31:14 <lament> also, identify patterns of brainfuck code that can be compiled into single instructions
08:32:52 <lament> ie balanced loops
08:34:15 <Guilt> i'm already coercing shifts and additions
08:34:29 <Guilt> is that what you are talking about?
08:35:44 <Guilt> er. balanced loops
08:35:45 <Guilt> er. balanced loops?
08:35:53 <Guilt> didn't get that one?
08:36:16 <lament> loops which don't move the memory pointer
08:36:21 <lament> eg [->++<]
08:36:40 <Guilt> that don't move it?
08:36:55 <lament> the memory pointer is unchanged by the loop
08:37:13 <lament> the effect is m[mp+1] = m[mp] * 2; m[mp] = 0;
08:37:20 <Guilt> well. but it's used to increase the adjacent cell by twice the current cell value
08:37:27 <Guilt> yea
08:37:32 <lament> i'm not sure what the "but" in your sentence means.
08:38:06 <Guilt> for small shifts it's okay. but with a moving loop and shift it's impossible.
08:38:37 <Guilt> like, to set all values to zero (of lower and current cell): [[-]<]
08:39:23 <lament> that's not a balanced loop.
08:39:27 <Guilt> yea
08:39:36 <lament> but [-] is
08:39:38 <Guilt> oh okay :)
08:40:06 <Guilt> hm. i see. a balanced loop contains balanced loops and doesn't change the memory pointer position\
08:40:42 <Guilt> alright. will read a bit about this :)
08:40:43 <Guilt> brb
08:40:47 <lament> good night
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09:58:39 <Guilt> back
09:58:45 <Guilt> lament, you slept?
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13:18:11 <oklopol> this time i actually understood (partly) what edwardk said!
13:18:19 <oklopol> oh the joy
14:26:01 <SimonRC> dadadadom
14:26:10 <ehird`> what did he say
14:26:36 <SimonRC> I was quoting Beethoven.
14:27:44 <ehird`> edwardk
14:27:46 <ehird`> i meant
14:29:57 <SimonRC> ahell of a lot
14:42:14 <oklopol> even though i'm pretty sure i understood, i am certainly not confident enough to try to explain it to you, so check the logs :P
14:43:36 <oklopol> i didn't get all of the monad stuff, but i mean last time i didn't understand one single sentence completely, i'm pretty sure :P
14:44:23 <oklopol> i did understand the idea, that was pretty obvious, but he's got a lot of words
14:55:10 <bsmntbombdood> SimonRC: Leck mich im Arsch
14:56:08 <bsmntbombdood> (just quoting beethoven)
14:56:15 <ehird`> mozart
14:56:16 <ehird`> actually
14:56:48 <bsmntbombdood> damnit
14:57:15 <bsmntbombdood> stupid identical old guys
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17:21:05 <SimonRC> bsmntbombdood: ?!
17:30:32 <oerjan> beethoven and mozart, presumably. famous decomposers.
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20:13:29 * ehird` is a famous decomposer
20:17:39 <RodgerTheGreat> like a maggot?
20:17:48 <ehird`> and beethoven and mozart
20:18:11 <RodgerTheGreat> no, those two are decomposing composers
20:18:47 <RodgerTheGreat> beethoven, for example, wasn't famous for his decomposing until after his death
20:21:14 <ehird`> oerjan
20:21:14 <ehird`> 17:29:47
20:21:14 <ehird`> beethoven and mozart, presumably. famous decomposers.
20:21:19 <ehird`> so ha
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22:48:33 <bsmntbombdood> how much work is a compiler allowed to do and still be called a compiler?
22:52:07 <oerjan> just about anything?
22:52:39 <oerjan> remember that a compiler cannot access actual runtime input, which limits things
22:52:53 <bsmntbombdood> only a little
22:53:13 * ehird` thinks that in /me's perfect language, compiler and interpreter would be the same word!
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23:43:14 <GregorR> bsmntbombdood: Compilers are just language translators that target languages not intended to be read by humans.
23:43:34 <GregorR> bsmntbombdood: If your program does something aside from language translation, it's not a compiler.
23:44:03 <bsmntbombdood> i was thinking about optimizations
23:44:11 <GregorR> I guess I can remove the clause "not intended to be read by humans"
23:44:46 <GregorR> bsmntbombdood: Optimization is a component of the translation. It's like translating a phrase into a coined expression instead of into a roundabout explanation.
23:45:05 <GregorR> (To compare it to real language translation)
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