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export interface IEither<E, T> {
ok?: T;
err?: E;
mapBoth: <Ee, Tt>(
errBranch: (e: E) => Ee,
okBranch: (o: T) => Tt,
) => IEither<Ee, Tt>;
}
export class Either<E, T> implements IEither<E, T> {
private constructor(readonly err?: E, readonly ok?: T) {}
public mapBoth<Ee, Tt>(errBranch: (e: E) => Ee, okBranch: (t: T) => Tt) {
if (this.err) return new Either<Ee, Tt>(errBranch(this.err));
return new Either<Ee, Tt>(undefined, okBranch(this.ok!));
}
static left<E, T>(e: E) {
return new Either<E, T>(e);
}
static right<E, T>(t: T) {
return new Either<E, T>(undefined, t);
}
}
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