public static Either <A, Option <BB> > flatMapT <A, B, BB>(
this Either <A, Option <B> > m, Fn <B, Option <BB> > mapper
) => m.mapRight(_ => _.flatMap(mapper));
public static Either <Left, IEnumerable <ElemTo> > mapRightC <CollFrom, Left, ElemFrom, ElemTo>(
this Either <Left, CollFrom> e,
Fn <ElemFrom, ElemTo> mapper
) where CollFrom : IEnumerable <ElemFrom> =>
e.mapRight(mapC <CollFrom, ElemFrom, ElemTo>(mapper));
[PublicAPI] public static Either <L, R1> Select <L, R, R1>(this Either <L, R> e, Fn <R, R1> f) => e.mapRight(f);
[PublicAPI] public static Either <A, Option <BB> > mapT <A, B, BB>(
this Either <A, Option <B> > m, Fn <B, BB> mapper
) => m.mapRight(_ => _.map(mapper));