Hello all,
I believe the following program is valid Haskell'98:
>>>
module Main where
data Hash = Hash{ (#) :: Int }
deriving (Show, Read)
main =
do print s
print (read s :: Hash)
where
s = show (Hash 3)
<<<
The problem is the use of (#) as a field name.
The expected output of the program is something like:
>>>
"Hash{(#)=3}"
Hash{(#)=3}
<<<
Hugs98's, Hbc's and Ghc's derived read and show
all choke on it though:
Hugs says:
>>>
"Hash{#=3}"
Program error: Prelude.read: no parse
<<<
Hbc says:
>>>
"Hash { (#) = 3 }"
Bug: Error: Prelude.read: no parse
<<<
Ghc says:
>>>
"Hash{#=3}"
Fail: PreludeText.read: no parse
<<<
The question is: should operators be allowed to be valid
field names or not?
Regards,
Koen.
--
Koen Claessen,
[EMAIL PROTECTED],
http://www.cs.chalmers.se/~koen,
Chalmers University of Technology.
