Module type Eva_lattice_type.With_Widening

module type With_Widening = Lattice_type.With_Widening

type t 
type widen_hint 
hints for the widening
val widen : widen_hint ->
t ->
t -> t
widen h t1 t2 is an over-approximation of join t1 t2. Assumes is_included t1 t2