Re: [Caml-list] Matching exhausitvity with GADT and modules

[Joris Giovannangeli <joris@giovannangeli.fr>]

> This is a common problem that has annoyed me as well. The issue is that
> B sees foo and bar as abstract types, so cannot be sure they are
> different, so cannot be sure that a value of type foo gadt can't be
> constructed with Bar. If you add explicit constructors for both
> currently-empty types, then their inequality will be exposed and your
> pattern match should work.

That's a nice workaround in the case where foo and bar and phantom types
indeed. Just adding a dummy constructor. In case they are real abstract
type, someone advised me to disable the exhaustivity warning locally
with [@@warning "-8"] code annotation, which is a bit more hack-ish.

Thanks