fromNullable<L, R> function

Either<L, R> fromNullable<L, R>(
  1. R? value,
  2. Lazy<L> orElse
)

Create an Either from a nullable value. If the value is null, then the result of the orElse function is used as a Left value.

expect(
  fromNullable('hello', () => 'it was null'),
  right('hello'),
);

expect(
  fromNullable(null, () => 'it was null'),
  left('it was null'),
);

Implementation

Either<L, R> fromNullable<L, R>(
  R? value,
  Lazy<L> orElse,
) =>
    value != null ? right(value) : left(orElse());