Interface Applicative<A>

Applicative functor - supports applying wrapped functions to wrapped values

Laws:

• Identity: pure(x => x).ap(v) ≡ v
• Composition: pure(compose).ap(u).ap(v).ap(w) ≡ u.ap(v.ap(w))
• Homomorphism: pure(f).ap(pure(x)) ≡ pure(f(x))
• Interchange: u.ap(pure(y)) ≡ pure(f => f(y)).ap(u)