Yes, I think you're getting the gist. Pattern matching with one or two
nulls is just an equality test or three. In practice, we'd want a fixed
number of evenly spaced nulls, allowing jump table techniques to be used
when there are more cases. We'd presumably have a hard limit for the number
of nulls a type is allowed to have.
On Wed, Oct 14, 2020, 10:29 AM Spiwack, Arnaud
Ok, I believe get it now,
Let's imagine (to take only the simplest case) that we have a `Nullable# a` type, such that `Nullable# a = (# (##) | a #)`. What would be the kind of `Nullable#`? I imagine that it would be something like `TYPE (BoxedRep Lifted) -> TYPE (BoxedRep Nullable)`.
Then you would want to abstract the type of arrays/tvars/whatnot from `Type -> Type` to `forall r. TYPE (BoxRep r) -> Type`.
Is that a correct interpretation of your suggestion?
If so, my guess would be that all the above is fine, but I suspect (and I'm quite a bit out of my comfort zone here) that there can be considerable difficulties in implementing pattern-matching for such a type.