- -- * If constraint is given then typeKind xi == typeKind tv
- -- See Note [Spontaneous solving and kind compatibility]
- -- in TcInteract
+ -- * If constraint is given then typeKind xi `compatKind` typeKind tv
+ -- See Note [Spontaneous solving and kind compatibility]
+ -- * If 'xi' is a flatten skolem then 'tv' can only be:
+ -- - a flatten skolem or a unification variable
+ -- i.e. equalities prefer flatten skolems in their LHS
+ -- See Note [Loopy Spontaneous Solving, Example 4]
+ -- Also related to [Flatten Skolem Equivalence Classes]