On Wednesday, 2002-10-16, 09:40, CEST, Simon Peyton-Jones wrote: > > I want to define something like > > class (Eq (forall a. T a), Monad T) => C T > > where the context shall mean that T has to be an instance of Monad > > and > > that for every type a the type T a has to be an instance of Eq. > > Is such a thing possible with some Haskell implementation? > > Not currently, but I think it makes sense, and I'll implement it if > enough people ask. > > Presumably you mean 'instance' not 'class'? A class decl always has a > type variable after the =>; thus ...=> C a.
Hello again, I mean "class" but I have made a mistake in the code above: The uppercase T should be a lowercase t. > There aren't many type constructors T for which T a is an equality > type... I only wanted to illustrate what kind of construction I'd like to have by using standard Haskell classes. In my application I don't use Eq. > Simon Wolfgang _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
