Type classes

export interface Lookup<F> {
  lookup: (key: Key<F>) => <A>(fa: HKT<F, A>) => Option<A>
}

export interface Lookup1<F extends Keyed1 & URIS> {
  lookup: (key: KeyOf1<F>) => <A>(fa: Kind<F, A>) => Option<A>
}

export interface Lookup2<F extends Keyed2 & URIS2> {
  lookup: <E>(key: KeyOf2<F, E>) => <A>(fa: Kind2<F, E, A>) => Option<A>
}

export interface Lookup2C<F extends Keyed2 & URIS2, E> {
  lookup: (key: KeyOf2<F, E>) => <A>(fa: Kind2<F, E, A>) => Option<A>
}

export interface Lookup3<F extends Keyed3 & URIS3> {
  lookup: <R, E>(key: KeyOf3<F, R, E>) => <A>(fa: Kind3<F, R, E, A>) => Option<A>
}

export interface Lookup3C<F extends Keyed3 & URIS3, E> {
  lookup: <R>(key: KeyOf3<F, R, E>) => <A>(fa: Kind3<F, R, E, A>) => Option<A>
}

export interface Lookup4<F extends Keyed4 & URIS4> {
  lookup: <S, R, E>(key: KeyOf4<F, S, R, E>) => <A>(fa: Kind4<F, S, R, E, A>) => Option<A>
}