Missing case for Constraint for fmap and <*>

[expipiplus1]

No description provided.

[expipiplus1]

Ahh! This is actually annoying for passing in monadic/user state to the productions because if we put the constraining function inside a Prod (as is done for Many and Alts) then we can't discover the nulls without the user state, and hence can't use user state for avoiding rerunning the grammar!

[ollef]

Oof. Can you see a way to implement it? Might have to be removed.

[expipiplus1]

As it is, the constraint production can't remain at the same type, because without a Prod which is positive in the eventual Constraint type we have nowhere to push <*> into.

The constraint function however wouldn't need to change as it could easily forward to Constraint myProd (Pure myPredicate)