The Preface of the Haskell Report says:
The comittee hopes that Haskell can serve as a basis for future research
in language design. We hope that extensions or variants of the language
may appear, incorporating experimental features.
Various extensions have been proposed or even implemen
Dear sir,
I had written several pages of Haskell scripts, tried HUGS Haskell
on them, debugged, and now I'm trying to complile the stuff with
Glasgow Haskell.
ghc-0.25 dislikes the following declarations:
-
module M where
instance (Num a, Num b) =>
Your error messages from ghc are correct: you have violated the
infamous C-T rule (section 4.3.2, page 32) which restricts instance
declarations to the module containing either the class or the
datatype. Since (,) and Num are both in the prelude, you can't
compile this in official Haskell 1.2.
