Module UnivProblemSource

Constraints for type inference

When doing conversion of universes, not only do we have =/<= constraints but also Lub constraints which correspond to unification of two levels which might not be necessary if unfolding is performed.

UWeak constraints come from irrelevant universes in cumulative polymorphism.

Sourceval is_trivial : t -> bool
Sourcemodule Set : sig ... end
Sourcetype 'a accumulator = Set.t -> 'a -> 'a option
Sourcetype 'a constrained = 'a * Set.t
Sourcetype 'a constraint_function = 'a -> 'a -> Set.t -> Set.t
Sourceval enforce_eq_instances_univs : bool -> Univ.Instance.t constraint_function
Sourceval to_constraints : force_weak:bool -> UGraph.t -> Set.t -> Univ.Constraint.t

With force_weak UWeak constraints are turned into equalities, otherwise they're forgotten.