[Haskell-cafe] Does GADTs imply ExistentialQuantification?

[David Feuer]

I'm not sure. Once you have GADTs, ExistentialQuantification is just
syntax. So from one angle, maybe it doesn't matter too much. On the other
hand, that syntax, whole traditional, is not the clearest in the world. One
could easily imagine a Haskell implementation that chooses only to support
GADT syntax for existentials. So maybe it is a bug.

On Aug 26, 2018 9:43 PM, "Cosmia Fu" <cosmiafu at gmail.com> wrote:

Hey everyone,

I found that it seems that GADTs implies ExistentialQuantification, but not
mentioned in the manual. Is it a bug?
https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#extension-GADTs

GHCi, version 8.4.3: http://www.haskell.org/ghc/  :? for help
Prelude> :set -XGADTs -XExplicitForAll
Prelude> data Q = forall a. Q a
Prelude>

----

Cosmia Fu
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