[GHC] #3212: getOptions'.parseLanguage(2) went past eof token

[GHC]

#3212: getOptions'.parseLanguage(2) went past eof token
---------------------------------------------------------------+------------
    Reporter:  Jig                                             |        Owner:         
        Type:  bug                                             |       Status:  new    
    Priority:  normal                                          |    Milestone:         
   Component:  Compiler                                        |      Version:  6.10.2 
    Severity:  minor                                           |   Resolution:         
    Keywords:  getOptions'.parseLanguage(2) XFlexibleContexts  |   Difficulty:  Unknown
    Testcase:                                                  |           Os:  Windows
Architecture:  Unknown/Multiple                                |  
---------------------------------------------------------------+------------
Changes (by simonmar):

  * difficulty:  => Unknown

Old description:

> {-# LANGUAGE -XFlexibleContexts #-}
> module Pngloadtest where
> import Control.Monad
> import Control.Arrow
> import Codec.Image.PNG
> import Data.Array.MArray
> import Data.Array.Storable
> import GHC.Word
> --import Data.Array.MArray
> import qualified Data.Matrix.DenseMatrix as DM
>
> openImage :: IO PNGImage
> openImage = do
>   a <- loadPNGFile "C:/users/saftarn/desktop/datasets/pics/face2.png"
>   case a of Left err  -> error err
>             Right img -> return img
>
> dims :: PNGImage -> (Int, Int)
> dims img = join (***) fromIntegral $ dimensions img
>
> size :: PNGImage -> Int
> size img = uncurry (*) $ dims img
>

> --imgToList :: (MArray StorableArray Word8 m, Num b) => PNGImage -> m [b]
> imgToList img = do
>   es <- getElems $ imageData img
>   return $ map fromIntegral es
>
> imgToMatrix :: (MArray StorableArray Word8 m) => PNGImage ->
>                m DM.DenseMatrix
> imgToMatrix im = do
>   let (w,_) = dims im
>   xs <- imgToList im
>   return $ DM.fromFlatList w xs
>
> main = do
>   im <- openImage
>   a <- imgToList im
>   print $ dims im
>   print $ size im
>   --print a
>

>

>
> *Pngloadtest> :load "ComputerVision/Pngloadtest.hs"
> [1 of 2] Compiling Data.Matrix.DenseMatrix ( Data\Matrix\DenseMatrix.hs,
> interpreted )
> [2 of 2] Compiling Pngloadtest      ( ComputerVision\Pngloadtest.hs,
> interpreted )
>
> ComputerVision\Pngloadtest.hs:29:0:
>     Non type-variable argument
>       in the constraint: MArray StorableArray Word8 m
>     (Use -XFlexibleContexts to permit this)
>     In the type signature for `imgToMatrix':
>       imgToMatrix :: (MArray StorableArray Word8 m) =>
>                      PNGImage -> m DM.DenseMatrix
> Failed, modules loaded: Data.Matrix.DenseMatrix.
> *Data.Matrix.DenseMatrix> :load "ComputerVision/Pngloadtest.hs"
> : panic! (the 'impossible' happened)
>   (GHC version 6.10.2 for i386-unknown-mingw32):
>         getOptions'.parseLanguage(2) went past eof token
>
> Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
>
> >
>

>

>

>

>

> Works if using:
> {-# LANGUAGE FlexibleContexts #-}

New description:

 {{{
 {-# LANGUAGE -XFlexibleContexts #-}
 module Pngloadtest where
 import Control.Monad
 import Control.Arrow
 import Codec.Image.PNG
 import Data.Array.MArray
 import Data.Array.Storable
 import GHC.Word
 --import Data.Array.MArray
 import qualified Data.Matrix.DenseMatrix as DM

 openImage :: IO PNGImage
 openImage = do
   a <- loadPNGFile "C:/users/saftarn/desktop/datasets/pics/face2.png"
   case a of Left err  -> error err
             Right img -> return img

 dims :: PNGImage -> (Int, Int)
 dims img = join (***) fromIntegral $ dimensions img

 size :: PNGImage -> Int
 size img = uncurry (*) $ dims img


 --imgToList :: (MArray StorableArray Word8 m, Num b) => PNGImage -> m [b]
 imgToList img = do
   es <- getElems $ imageData img
   return $ map fromIntegral es

 imgToMatrix :: (MArray StorableArray Word8 m) => PNGImage ->
                m DM.DenseMatrix
 imgToMatrix im = do
   let (w,_) = dims im
   xs <- imgToList im
   return $ DM.fromFlatList w xs

 main = do
   im <- openImage
   a <- imgToList im
   print $ dims im
   print $ size im
   --print a





 *Pngloadtest> :load "ComputerVision/Pngloadtest.hs"
 [1 of 2] Compiling Data.Matrix.DenseMatrix ( Data\Matrix\DenseMatrix.hs,
 interpreted )
 [2 of 2] Compiling Pngloadtest      ( ComputerVision\Pngloadtest.hs,
 interpreted )

 ComputerVision\Pngloadtest.hs:29:0:
     Non type-variable argument
       in the constraint: MArray StorableArray Word8 m
     (Use -XFlexibleContexts to permit this)
     In the type signature for `imgToMatrix':
       imgToMatrix :: (MArray StorableArray Word8 m) =>
                      PNGImage -> m DM.DenseMatrix
 Failed, modules loaded: Data.Matrix.DenseMatrix.
 *Data.Matrix.DenseMatrix> :load "ComputerVision/Pngloadtest.hs"
 : panic! (the 'impossible' happened)
   (GHC version 6.10.2 for i386-unknown-mingw32):
         getOptions'.parseLanguage(2) went past eof token

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

 >
 }}}









 Works if using:
 {-# LANGUAGE FlexibleContexts #-}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3212#comment:1>
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