Function isLeft

isLeft<E, A>(
either: Either<E, A>,
): either is Readonly<{ isRight: false; left: E }>
Type guard that checks if an either is Left<E>.
Type Parameters
- E
- A
Parameters
- either: Either<E, A>
  The Either to check
Returns either is Readonly<{ isRight: false; left: E }>
true if the Either is Left<E>, false if it is Right<A>
- Defined in packages/util-ts/src/lib/functional/either.ts:77