Re: [Haskell-cafe] Fun with multi-parameter type classes

On Thu, 19 Aug 2004, Sam Mason wrote:

class Foo t where encode :: String -> t decode :: t -> String

test = decode . encode

This currently fails, because the type checker insists on trying to figure out what its type should be - even though it shouldn't be needed.

In contrast to that, test = encode . decode should not fail. :-) Btw. for my association of the names 'encode' and 'decode' the signatures are the other way round, i.e.

decode :: String -> t encode :: t -> String