@lucaspaganini/value-objects/src/utils/either.ts

TypeScript first validation and class creation library

export interface Left<L> {
  _tag: 'Left'
  left: L
}

export interface Right<R> {
  _tag: 'Right'
  right: R
}

export type Either<L, R> = Left<L> | Right<R>

export const isLeft = <L, R>(either: Either<L, R>): either is Left<L> => either._tag === 'Left'

export const isRight = <L, R>(either: Either<L, R>): either is Right<R> => either._tag === 'Right'

export const left = <L>(value: L): Left<L> => ({
  _tag: 'Left',
  left: value,
})

export const right = <R>(value: R): Right<R> => ({
  _tag: 'Right',
  right: value,
})