Is there a workaround for this bug?

[Dominic Steinitz]

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