eq-lifting.go

/*

FromEq is a combinator that lifts T ⟼ T ⟼ bool function to
an instance of Eq type trait
*/
type FromEq[T any] func(T, T) bool

// implementation of Eq type class 
func (f FromEq[T]) Equal(a, b T) bool { return f(a, b)}


// Equal is a pure function that compares two integers
func Equal(a, b int) bool { return a == b }

/*

The combinator creates a new instance of Eq trait
that "knows" how to compare int.
*/
var Int Eq[int] = eq.FromEq[int](Equal)