[Haskell-cafe] type/class question: toString

[Graham Fawcett]

Hi folks,

Is there a way to declare a 'toString' function, such that

toString x | <x is a String> = x
toString x | <x's type is an instance of Show> = show x

Perhaps, in the type system, there's a way to declare a ToString
class, and somehow "inherit" all instances of Show as ToString
instances?

Thanks,
Graham