Brandon S. Allbery KF8NH wrote:
On Oct 19, 2007, at 12:11 , Sebastian Sylvan wrote:
On 19/10/2007, Kalman Noel <[EMAIL PROTECTED]> wrote:
data ExistsNumber = forall a. Num a => Number a
I'm without a Haskell compiler, but shouldn't that be "exists a."?
The problem is that "exists" is not valid in either Haskell 98 or any
current extension, whereas "forall" is a very common extension. But you
can simulate "exists" via "forall", which is the thrust of these
approaches.
When 'exists' is not a keyword, why 'forall' is needed at all?
Isn't everything 'forall' qualified by default? ... or are type
variables sometimes 'exists' qualified by default depending
on context? That would be confusing though...
I do not understand why 'forall' keyword is needed.
Peter.
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