Data.Constraint.Trivial

Documentation

class Unconstrained t

Intended to be used as an argument for some type constructor which expects kind * -> Constraint, when you do not actually wish to constrain anything with it.

Unconstrained t can always be added to the constraint list of any signature, without changing anything.

Instances

Unconstrained t

type Impossible t = HiddenEmptyClass t

This constraint can never be fulfilled. Might be useful e.g. as a default for a class-associated constraint; this basically disables any method with that constraint (so it can safely be left undefined).