Sam Mason writes:
Jon Cast wrote:
The intermediate type /is/ needed---it's a (hidden) parameter to your `encode' and `decode' functions. Why do you think it shouldn't be?
Because I couldn't see the woods for the trees. I think I had almost figured out what I was asking (the impossible) before your message appeared. ...
Don't forget that this is the toplevel business, not a universal "disease". GHCi says Prelude> :t (show . read) (show . read) :: String -> String and doesn't complain. But if you define bz = show . read the attempt to load this definition (file: ctest.hs) results in: ctest.hs:3: Ambiguous type variable `a' in these top-level constraints: `Read a' arising from use of `read' at ctest.hs:5 `Show a' arising from use of `show' at ctest.hs:5 Failed, modules loaded: none. Prelude> So, as one of my friends used to say: it should be obvious for everybody that what is obvious for one, need not be obvious for the others... Jerzy Karczmarczuk