Is there a workaround for this bug?

[Roman Cheplyaka]

Hi Dom,

I can confirm that your example compiles (with minimal adjustments)
under GHC 7.6.2 RC1. You can get it here:

http://www.haskell.org/ghc/dist/7.6.2-rc1/

Roman

* Dominic Steinitz <dominic at steinitz.org> [2013-01-01 20:30:10+0000]
> Thanks - I'll probably wait for the next release.
> 
> On 1 Jan 2013, at 19:48, Simon Peyton-Jones <simonpj at microsoft.com> wrote:
> 
> > I think the patch did get into 7.6.2 (which is about to be released) though.
> > 
> > I don't think there's a workaround, except by not using External Core, or not using Integer literals (use Ints?).  Sorry.
> > 
> > Simon
> > 
> > |  -----Original Message-----
> > |  From: glasgow-haskell-users-bounces at haskell.org [mailto:glasgow-haskell-users-
> > |  bounces at haskell.org] On Behalf Of Dominic Steinitz
> > |  Sent: 26 December 2012 18:14
> > |  To: glasgow-haskell-users at haskell.org
> > |  Subject: Is there a workaround for this bug?
> > |  
> > |  AFAICT this bug fix http://hackage.haskell.org/trac/ghc/ticket/7239 did not make
> > |  it into 7.6.1. Also I am happily working on the Haskell Platform with 7.4.1 and I'd
> > |  rather avoid upgrading if possible.
> > |  
> > |  Is there a workaround? I've attached my code below along with the error message
> > |  (which is the same as in the above bug report). I'm rather hoping I won't have to
> > |  build HEAD.
> > |  
> > |  Thanks, Dominic.
> > |  
> > |  bash-3.2$ ghc -fext-core --make Test.hs
> > |  [1 of 1] Compiling Main             ( Test.hs, Test.o )
> > |  ghc: panic! (the 'impossible' happened)
> > |   (GHC version 7.4.1 for x86_64-apple-darwin):
> > |  	MkExternalCore died: make_lit
> > |  
> > |  {-# LANGUAGE FlexibleContexts #-}
> > |  
> > |  {-# OPTIONS_GHC -Wall -fno-warn-name-shadowing -fno-warn-type-defaults #-}
> > |  
> > |  import Data.Array.Repa as Repa
> > |  import Data.Array.Repa.Eval
> > |  import Control.Monad
> > |  
> > |  r, sigma, k, t, xMax, deltaX, deltaT :: Double
> > |  m, n :: Int
> > |  r = 0.05
> > |  sigma = 0.2
> > |  k = 50.0
> > |  t = 3.0
> > |  m = 80
> > |  xMax = 150
> > |  deltaX = xMax / (fromIntegral m)
> > |  n = 800
> > |  deltaT = t / (fromIntegral n)
> > |  
> > |  data PointedArrayU a = PointedArrayU Int (Array U DIM1 a)
> > |   deriving Show
> > |  
> > |  f :: PointedArrayU Double -> Double
> > |  f (PointedArrayU j _x) | j == 0 = 0.0
> > |  f (PointedArrayU j _x) | j == m = xMax - k
> > |  f (PointedArrayU j  x)          = a * x! (Z :. j-1) +
> > |                                   b * x! (Z :. j) +
> > |                                   c * x! (Z :. j+1)
> > |   where
> > |     a = deltaT * (sigma^2 * (fromIntegral j)^2 - r * (fromIntegral j)) / 2
> > |     b = 1 - deltaT * (r  + sigma^2 * (fromIntegral j)^2)
> > |     c = deltaT * (sigma^2 * (fromIntegral j)^2 + r * (fromIntegral j)) / 2
> > |  
> > |  priceAtT :: PointedArrayU Double
> > |  priceAtT = PointedArrayU 0 (fromListUnboxed (Z :. m+1)
> > |                            [ max 0 (deltaX * (fromIntegral j) - k) | j <- [0..m] ])
> > |  
> > |  coBindU :: (Source U a, Source U b, Target U b, Monad m) =>
> > |            PointedArrayU a -> (PointedArrayU a -> b) -> m (PointedArrayU  b)
> > |  coBindU (PointedArrayU i a) f = computeP newArr >>= return . PointedArrayU i
> > |   where
> > |       newArr = traverse a id g
> > |         where
> > |           g _get (Z :. j) = f $ PointedArrayU j a
> > |  
> > |  testN :: Int -> IO (PointedArrayU Double)
> > |  testN n =  h priceAtT
> > |            where
> > |            h = foldr (>=>) return
> > |                (take n $ Prelude.zipWith flip (repeat coBindU) (repeat f))
> > |  
> > |  main :: IO ()
> > |  main = do r <- testN n
> > |           putStrLn $ show r
> > |  
> > |  
> > |  _______________________________________________
> > |  Glasgow-haskell-users mailing list
> > |  Glasgow-haskell-users at haskell.org
> > |  http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
> 
> 
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