arrow bug

Initially reported here: http://www.haskell.org/pipermail/glasgow-haskell-users/2010-July/019035.html

This program:

{-# LANGUAGE Arrows #-}
module Main where

import Control.Arrow

foo :: (b -> String) -> ((((b, Int), Float), Double) -> String) -> (b -> String)
foo f g b = f b ++ " " ++ g (((b, 8), 1.0), 6.0)

bar :: (t -> String) -> ((t, Double, Float, Int) -> String) -> t -> String
bar f g  = proc x -> do
  (f -< x) `foo` \n m k -> g -< (x,n,m,k)

main = do
  putStrLn $ foo show show 17
  putStrLn $ bar show show 17
  putStrLn $ foo show show 42
  putStrLn $ bar show show 42

produces the wrong output:

17 (((17,8),1.0),6.0)
17 (17,4.0e-323,1.0,4618441417868443648)
42 (((42,8),1.0),6.0)
42 (42,4.0e-323,1.0,4618441417868443648)

Note that, e.g.,

*Main GHC.Exts GHC.Prim> D# (unsafeCoerce# 4618441417868443648#)
6.0

-dcore-lint failes with multiple errors.

Trac metadata

Trac field	Value
Version	6.12.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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