javascript-either

Either Implementation

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English

Introduction

This implementation represents a type that can hold either a value of type L (Left) or a value of type R (Right). It is a common pattern in functional programming to handle computations that can result in two different types of outcomes, such as success or failure.

Usage

Creating an Either instance

To create an Either instance, you can use the static methods left and right:

const { Either } = require('./either');

// Create a Left value
const leftValue = Either.left('Error occurred');

// Create a Right value
const rightValue = Either.right(42);

Checking the type of the value

if (leftValue.isLeft) {
  console.log('This is a Left value');
}

if (rightValue.isRight) {
  console.log('This is a Right value');
}

Output

const left = leftValue.left(); // 'Error occurred'
const right = rightValue.right(); // 42