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GHC 6.4.1 x86-64 does not compile
by Dusan Kolar 09 May '06

09 May '06

Hello all, I've install "universal binary" for x86_64 of GHC 6.4.1. The installation was done on AMD dual core machine. Uname for the machine gives: Linux <machine name> 2.6.16.5 #1 SMP Thu Apr 13 09:08:22 CEST 2006 x86_64 x86_64 x86_64 GNU/Linux While ghci was running some tests well, the ghc ended compilation with a long list of errors starting like this: Chasing modules from: queen-main Compiling QueensDK ( ./QueensDK.hs, ./QueensDK.o ) /tmp/ghc27286.s: Assembler messages: /tmp/ghc27286.s:26: Error: bad register name `%r12' /tmp/ghc27286.s:27: Error: bad register name `%r15' /tmp/ghc27286.s:29: Error: bad register name `%r12)' /tmp/ghc27286.s:30: Error: bad register name `%r12)' /tmp/ghc27286.s:31: Error: bad register name `%r12)' /tmp/ghc27286.s:32: Error: bad register name `%rax' /tmp/ghc27286.s:33: Error: bad register name `%r13)' /tmp/ghc27286.s:34: Error: bad register name `%rbp' /tmp/ghc27286.s:37: Error: bad register name `%rbx)' /tmp/ghc27286.s:38: Error: bad register name `%rbx)' /tmp/ghc27286.s:45: Error: bad register name `%rbp)' /tmp/ghc27286.s:46: Error: bad register name `%r14' /tmp/ghc27286.s:48: Error: bad register name `%rbp)' /tmp/ghc27286.s:49: Error: bad register name `%r13' ... The list is quite long. I've truncated it. Well, OK, the x386 version is running, but it won't compile GHC-6.4.2 and, moreover, it's not optimized for the HW. ;-) Is there any way out, or what may I be doing wrong way? Regards, Dusan

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Predicate Library?
by Neil Mitchell 09 May '06

09 May '06

Hi, I'm trying to manipulate predicates in Haskell, and was wondering if there was a predicate library available that I could use? My predicates consist of `and` and `or` over some constraints. I have various rules which can be used to collapse certain constraints. Currently I have written my own predicate code, but its not great, and the simplification is overly hacky. The main facility I want out of the predicate library is some simplification. Thanks Neil

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Partial Derivatives
by Gerhard Navratil 09 May '06

09 May '06

Hi, I need a library that provides partial derivatives for functions. The solution I came up with is based on a datatype using reversed polish notation to store the function: Type VarName = String data Fkt a = Val a | Var VarName | Add (FktElem a) (FktElem a) | Sub (FktElem a) (FktElem a) | Mul (FktElem a) (FktElem a) | ... I can then use pattern matching to compute the derivative: derivative :: VarName -> Fkt b -> Fkt b derivative name (Var n) = if n == name then Val 1.0 else Val 0.0 derivative name (Add a b) | (containsVar name a) && (containsVar name b) = Add (derivative name a) (derivative name b) | (containsVar name a) && (not(containsVar name b)) = (derivative name a) | (not(containsVar name a)) && (containsVar name b) = (derivative name b) | otherwise = Val 0.0 derivative name (Sub a b) | (containsVar name a) && (containsVar name b) = Sub (derivative name a) (derivative name b) | (containsVar name a) && (not(containsVar name b)) = (derivative name a) | (not(containsVar name a)) && (containsVar name b) = (derivative name b) | otherwise = Val 0.0 derivative name (Mul a b) | (containsVar name a) && (containsVar name b) = Add (Mul (derivative name a) b) (Mul a (derivative name b)) | (containsVar name a) && (not(containsVar name b)) = Mul (derivative name a) b | (not(containsVar name a)) && (containsVar name b) = Mul a (derivative name b) | otherwise = Val 0.0 ... Where the function containsVar :: VarName -> Fkt a -> Bool tests if a function contains the variable. The solution works but is not very elegant. The complete module is appended to the mail. Does anyone have a more elegant solution or is there a package that provides derivatives in a similar way? Thank you, Gerhard ======================================== Gerhard Navratil Teaching- And Research-Assistant Technical University Vienna, Austria Institute of Geoinformation and Cartography Gusshausstr. 27-29, 1040 Vienna Tel.: ++43 (0) 1 / 58 801 - 12712 Fax.: ++43 (0) 1 / 58 801 - 12799 Cel.: ++43 (0) 699 / 197 44 761 http://www.geoinfo.tuwien.ac.at

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Re: [Haskell] how to 'accumulate' values efficiently (time and space) ?
by dons＠cse.unsw.edu.au 08 May '06

08 May '06

noteed: > Hi all, > > the problem is simple but i can't do it : > > I want to generate some values and 'accumulate' them. The meaning of > 'accumulating' is not so important. The only point is that to > 'accumulate' the values, I only have to know one value and the > accumulator (and not all the values). > > The most simple example is that of adding a list of numbers. > > I thought that I could use a haskell list to represent the values > so I could use foldr or mapM to do the accumulation (and not an > imperative-style loop). > > Below are four attempts to solve the problem. It's not solved : in > ghci, I have '*** Exception: stack overflow' with 'test1 5000000'. > > 5000000 is not so much for my application. > > How can I achieve what I want (and efficiently)? > ---------------------------------------------------------------------} > > import Control.Monad.State > import Control.Monad.ST > import Data.STRef > > acc1, acc2, acc3 :: [Int] -> Int > > ---------------------------------------------------------------------- > > acc1 ints = foldr (+) 0 ints Strictify the accumulator? Prelude List Data.List> foldl1 (+) (replicate 5000000 1) *** Exception: stack overflow versus Prelude List Data.List> foldl1' (+) (replicate 5000000 1) 5000000 (Redirected to haskell-cafe@) -- Don

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throwing sugar into the void.
by Marc A. Ziegert 07 May '06

07 May '06

Hi@all! I'd like to hear some comments about the following ideas; maybe they are someway obsolete or even useless nonsense. A few days ago, I thought about abstracting the instance of an object away, like used in Foreign.Storable.sizeOf::(Storable a)=>a->Int, where only the type of an object is used. The problem with the function sizeOf is, that the result should be constant per definition(*), but how can we make the compiler know this? (*) <http://www.haskell.org/ghc/docs/latest/html/libraries/base/Foreign-Storable…> > sizeOf::a->Int > "Computes the storage requirements (in bytes) of the argument. The value of the argument is not used." So I thought we may need a new (abstract) datatype to wrap the type of an object, just to contain no dynamic data: data Type a typeOf :: a -> Type a typeOf = undefined #define TYPE(a) (undefined::Type (a)) ... sizeOf :: (Storable a) => Type a -> Int Maybe this is a little bit too ugly and cumbersomely, just to make sizeOf constant. This version of sizeOf is not really comfortable anymore; but it isn't comfortable to write "(undefined::a)", too. To be able to write "(::a)" instead, would be really nice, IMHO; but how about "(_::a)"? ---------- <trying to be equivocating> undefined is another way to implement ...nothing. </trying to be equivocating> More comfortable would it be to write a single symbol instead of the long word "undefined": _ :: a _ = undefined Using "_" as a function should not be such a problem: it cannot be mixed with the joker "_" as parameter. To define this function may be a problem: It needs a compiler-patch to allow this, ATM. ---------- By the way, this symbol is not used at type-level... How about praefix/postfix operators instead of only infix? -- praefix newtype BigLambda a = BigLambda a (/\) :: _ -> a -> BigLambda a /\ a = BigLambda a -- postfix newtype Lifted a = Lifted a (!^) :: a -> _ -> Lifted a a !^ = Lifted a May this be confusing? Or even impossible? Am I insane? Well, I don't know how hard it would be to implement those language features. I would not like to make anyone implement all this, if it is only a niceToHave-butIDontUseIt, like the implicit parameters feature. - marc

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Haddock seems to generate wrong types in newtype deriving
by Brian Hulley 06 May '06

06 May '06

Hi - I have the following code: data MState = MState -- details omitted type MonadStateMState = MonadState MState -- necessary for Haddock newtype ManagerM a = ManagerM (StateT MState IO a) deriving (Monad, MonadIO, MonadStateMState) which means that ManagerM is an instance of Monad, MonadIO, and MonadState MState. However, the Haddock docs look like: data ManagerM a Instances ??? a => Monad (ManagerM a) ??? a => MonadIO (ManagerM a) ??? a => MonadStateMState (ManagerM a) which doesn't seem at all right to me. I'd have thought it should say: data ManagerM a Instances Monad ManagerM MonadIO ManagerM MonadStateMState ManagerM Is this just a bug in Haddock or am I misunderstanding something about Haskell? Thanks, Brian.

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need help please [HOpenGL]
by enache alex 06 May '06

06 May '06

hello ; I am writing to ask you a thing ; I am writing a little game on Haskell's HOpenGL ; the game isn't much , but I want to make look a little better ; and for that I want to use bitmaps (or textures) ; I don't know very much about this subject ; I've tried to use de bitmap function from Graphics.Rendering.OpenGL.GL.Bitmap , but i gives me an error ; I've used the function like this ; bmp <- bitmap (Size (100,100)) (Vertex2 0 0 ) (Vector2 0 0 ) (Ptr "C:\1.bmp") end it tells me that he doesn't find the Ptr constructor ; if you can supply an full example on this matter it would great ; many thanks ; hope to hear from you soon ; thanks for your time in reading my letter ; PS : the example doesn't have to be big , it just has to contain all the things , in order for me not to miss something --------------------------------- Yahoo! Messenger with Voice. Make PC-to-Phone Calls to the US (and 30+ countries) for 2¢/min or less.

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The case of the missing module
by ihope 06 May '06

06 May '06

In the Haddock source, there's the following line: import Paths_haddock ( getDataDir ) Paths_haddock doesn't seem to be anywhere inside the Haddock distribution, and a Google search doesn't turn up any useful results. Where can I find this thing?

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Re: [Haskell-cafe] #if and #endif
by ihope 06 May '06

06 May '06

On 4/13/06, Jason Dagit <dagit(a)codersbase.com> wrote: > Try using passing -cpp to ghc when you compile. > > Jason Thanks. Will do.

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NewBinary/ BinMem and IO monad
by Marc Weber 06 May '06

06 May '06

I'm trying to write some true type library (implementing only the tables I need at the moment). When loading a font file it doesn't make sense to "parse" every table which isn't needed. So lazyness of haskell would perfectly meet requirements here. My problem: NewBinary supports memory buffers. After loading a file to mem it can't change anymore so I no longer need an IO monad. It looks like this: bh <- readBinMem "file" b::Word8 <- get bh Of cause I can't remove the monad here because bh contains an internal pointer to the current position... but it might be done returning the new pointer: (bh2,b::Word8) = get bh ? Then I would be able to lazily parse the tables eg: getTable1 bh = do bh = seek bh offset -- seek to the beginning of the table get binary data and build internal representation return list of glyph and outlines and ... of cause this mem should be readonly then.. Would it make sense to implement this? Does it already exist? Marc

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