filterOrElse method

Either<L, R> filterOrElse(
  1. bool f(
    1. R r
    ),
  2. L onFalse(
    1. R r
    )
)

If f applied on this Either as Right returns true, then return this Either. If it returns false, return the result of onFalse in a Left.

Implementation

Either<L, R> filterOrElse(bool Function(R r) f, L Function(R r) onFalse) =>
    flatMap((r) => f(r) ? Either.of(r) : Either.left(onFalse(r)));