Hi Fergus.
data OrdFuncExist = OE (Ord a = Char - a)
That's not the syntax for a existential type,
that's the syntax for a universally quantified type
with rank-2 polymorphism. With that syntax, the
argument of `OE' must be a polymorphic function
with type `forall a . Ord a = Char -
Hi Alex,
| Here's some of the threatened examples:
|
| data OrdFuncExist = OE (Ord a = Char - a)
| data OrdListExist = OLE (Ord a = [a])
Perhaps this is a GHC/Hugs difference, but the syntax that you've
used here isn't permitted in Hugs ... and in old versions where it
might have been
On 22-Nov-1999, Alex Ferguson [EMAIL PROTECTED] wrote:
Here's some of the threatened examples:
data OrdFuncExist = OE (Ord a = Char - a)
That's not the syntax for a existential type,
that's the syntax for a universally quantified type
with rank-2 polymorphism. With that syntax, the
Hi Mark, all: thanks for the swiftly muddle-dispelling response.
| Here's some of the threatened examples:
|
| data OrdFuncExist = OE (Ord a = Char - a)
| data OrdListExist = OLE (Ord a = [a])
Perhaps this is a GHC/Hugs difference, but the syntax that you've
used here isn't
On 22-Nov-1999, Alex Ferguson [EMAIL PROTECTED] wrote:
Is this supposed to be a heterogenous list,
or a homogeneous list?
Sorry, I should have been a tad less terse: it's intended to be
a homogeneous list, else the maximum wouldn't be well-typed.
Oh, of course -- you're quite correct.
