[Haskell-cafe] Same compiled program behaving differently when called from ghci and shell

21 Nov 2010

      Hello,
I have a very strange (for me) problem that I manage to reduce to this :
I have a small program that reads a file with 1 only character (è = e8)
The program is ftest2.hs :

import IO

import Data.Maybe

tfind s = lookup (head s) $ zip ['\xe8', '\xde'] "12"

main    = do

             h<- readFile "g:\\CODE\\rlib\\test.txt"

             putStrLn h

             print $ tfind h

I compile it from command line :

ghc --make ftest2.hs

Now the weird results :
1/ cmd line:

ftest2.exe

è

Just '2'

2/ ghci

Prelude>  :!ftest2.exe

è

Just '2'

3/WinGHci

Prelude>  :! ftest2.exe

è

Just '1'

I tested different variants, there is always a difference.
Any idea to help me trace this behaviour ?

[Haskell-cafe] Same compiled program behaving differently when called from ghci and shell

Bruno Damour