#4236: arrow bug
---------------------------------+------------------------------------------
Reporter: igloo | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.14.1
Component: Compiler | Version: 6.12.3
Keywords: | Testcase:
Blockedby: | Difficulty:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
---------------------------------+------------------------------------------
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.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4236>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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