@philiprehberger/result-chain
v0.1.6598 downloadsMIT
Chainable Result monad for error handling without exceptions
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npm install @philiprehberger/result-chainREADME
@philiprehberger/result-chain
Chainable Result monad for error handling without exceptions
Installation
npm install @philiprehberger/result-chain
Usage
import { ok, err, Result } from '@philiprehberger/result-chain';
// Create results
const success = ok(42);
const failure = err('something went wrong');
// Chain operations
const result = ok(10)
.map((v) => v * 2)
.flatMap((v) => (v > 15 ? ok(v) : err('too small')))
.mapErr((e) => `Error: ${e}`);
// Extract values
const value = result.unwrapOr(0);
// Pattern match
const message = result.match({
ok: (v) => `Got ${v}`,
err: (e) => `Failed: ${e}`,
});
// Wrap throwable functions
const parsed = Result.fromThrowable(() => JSON.parse(rawInput));
// Wrap promises
const fetched = await Result.fromPromise(fetch('/api/data'));
// Combine results
const all = Result.all([ok(1), ok(2), ok(3)]); // Ok([1, 2, 3])
const settled = Result.allSettled([ok(1), err('x')]); // Ok({ ok: [1], err: ['x'] })
API
Factories
ok<T, E>(value: T): Result<T, E>- Creates an Ok result containing the given value.err<E, T>(error: E): Result<T, E>- Creates an Err result containing the given error.
Instance Methods
.isOk(): boolean- Returnstrueif the result is Ok..isErr(): boolean- Returnstrueif the result is Err..map<U>(fn: (value: T) => U): Result<U, E>- Transforms the Ok value, leaving Err untouched..mapErr<F>(fn: (error: E) => F): Result<T, F>- Transforms the Err value, leaving Ok untouched..flatMap<U, F>(fn: (value: T) => Result<U, F>): Result<U, E | F>- Chains a function that returns a Result..unwrap(): T- Returns the Ok value or throws if Err..unwrapOr(defaultValue: T): T- Returns the Ok value or the provided default..unwrapOrElse(fn: (error: E) => T): T- Returns the Ok value or computes a default from the error..match<U>(handlers: { ok, err }): U- Pattern matches on the result, calling the appropriate handler.
Static Methods
Result.fromPromise<T, E>(promise: Promise<T>): Promise<Result<T, E>>- Wraps a promise, catching rejections as Err.Result.fromThrowable<T, E>(fn: () => T): Result<T, E>- Wraps a function that may throw into a Result.Result.all<T, E>(results: Result<T, E>[]): Result<T[], E>- Returns Ok with all values if every result is Ok, otherwise the first Err.Result.allSettled<T, E>(results: Result<T, E>[]): Result<{ ok: T[]; err: E[] }, never>- Collects all results, separating Ok values and Err errors.
Development
npm install
npm run build
npm run typecheck
npm test
Support
If you find this project useful: