purify-ts

import { Maybe, Either, Just, Nothing, Left, Right } from 'purify-ts'; // Example 1: Handling optional values with Maybe function getUserEmail(id: number): Maybe<string> { const users = { 1: { name: 'Alice', email: 'alice@example.com' }, 2: { name: 'Bob', email: undefined }, 3: { name: 'Charlie', email: 'charlie@example.com' } }; const user = users[id]; return Maybe.fromNullable(user?.email); // Safely get email, handles null/undefined } console.log(`User 1 email: ${getUserEmail(1).map(e => e.toUpperCase()).getOrElse('No email found')}`); // Expected: User 1 email: ALICE@EXAMPLE.COM console.log(`User 2 email: ${getUserEmail(2).map(e => e.toUpperCase()).getOrElse('No email found')}`); // Expected: User 2 email: No email found console.log(`User 4 email: ${getUserEmail(4).map(e => e.toUpperCase()).getOrElse('No email found')}`); // Expected: User 4 email: No email found // Example 2: Working with Either for success/failure function divide(a: number, b: number): Either<string, number> { return b === 0 ? Left('Cannot divide by zero') : Right(a / b); } const result1 = divide(10, 2); result1.ifRight(val => console.log(`10 / 2 = ${val}`)); // Expected: 10 / 2 = 5 result1.ifLeft(err => console.error(`Error: ${err}`)); const result2 = divide(10, 0); result2.ifRight(val => console.log(`10 / 0 = ${val}`)); result2.ifLeft(err => console.error(`Error: ${err}`)); // Expected: Error: Cannot divide by zero // Example 3: Using fromPredicate with type guards const isPositive = (num: number): num is number => num > 0; const maybePositive = Maybe.fromPredicate(isPositive, 5); console.log(`Is 5 positive? ${maybePositive.isJust()}`); // Expected: Is 5 positive? true const maybeNegative = Maybe.fromPredicate(isPositive, -1); console.log(`Is -1 positive? ${maybeNegative.isJust()}`); // Expected: Is -1 positive? false