Proposal: Deprecate ExistentialQuantification

[Antoine Latter]

On Sat, Jun 27, 2009 at 5:44 AM, Niklas Broberg<niklas.broberg at gmail.com> wrote:
> Hi all,
>
> Following the discussion on the use of 'forall' and extensions that
> use it [1], I would hereby like to propose that the
> ExistentialQuantification extension is deprecated.
>
> My rationale is as follows. With the introduction of GADTs, we now
> have two ways to write datatype declarations, the old simple way and
> the GADTs way. The GADTs way fits better syntactically with Haskell's
> other syntactic constructs, in all ways. The general style is
> (somewhat simplified) "keyword type 'where' decls", where keyword can
> in Haskell 98 be class or instance, but with GADTs also data. The old
> simple way of defining data types is the odd one out. It certainly has
> its uses though, in particular when defining some simple (but possibly
> large) enum-like datatype (like cabal's Extension type incidentally),
> then it obviously becomes tedious to have to restate the trivial type
> signature for each constructor.

How does the support of the extensions differ between existing implementations?

Antoine