Constraints that any type, resp. no type fulfills https://github.com/leftaroundabout/trivial-constraint
|Version on this page:||0.5.1.0|
|Stackage Nightly 2019-07-18:||0.6.0.0|
|Latest on Hackage:||0.6.0.0|
Since GHC 7.4, constraints are first-class: we have the constraint kind, and thus type-classes have a kind such as
* -> Constraint.
These can be used as parameters to data types. They also can be combined quite nicely,
type NewConstraint a = (Constraint1 a, Constraint2 a)
however you always need to start with a plain old type class when building constraints.
This library provides a type class that is not really a constraint at all, so you can "start from zero" with building up a custom constraint. Also its opposite (a constraint that no type can ever fulfill).