Re: ANNOUNCE: GHC 7.4.1 Release Candidate 1

Am Donnerstag, den 22.12.2011, 00:02 +0100 schrieb Bas van Dijk:

On 21 December 2011 19:29, Ian Lynagh wrote:

...

* There is a new feature constraint kinds (-XConstraintKinds): http://www.haskell.org/ghc/dist/stable/docs/html/users_guide/constraint-kind...

I'm trying to run the ConstraintKinds example from the documentation:

{-# LANGUAGE ConstraintKinds, TypeFamilies #-} type family Typ a b :: Constraint type instance Typ Int b = Show b type instance Typ Bool b = Num b

But GHC complains: Not in scope: type constructor or class `Constraint'

By the way, is there a reason behind the fact that “Constraint” uses the ordinary case, while “BOX” has all three letters capitalized? Wouldn’t it be more sensible if it were “Box” instead of “BOX”? Things like capitalization might not seem very important first, but unfortunately, decisions about them seem to persist. Best wishes, Wolfgang