Quickstart

This quickstart shows the core Funkcia flow: model expected failures with Option/Result, then use OptionAsync/ResultAsync for async workflows.

Install

pnpm add funkcia

Import what you need

import { Option, Result } from 'funkcia';
import { OptionAsync } from 'funkcia/option-async';
import { ResultAsync } from 'funkcia/result-async';

Start with Option

Use Option for missing values without throwing.

import { Option } from 'funkcia';

declare function findUserEmail(userId: string): string | null;

const email = Option.fromNullable(findUserEmail('user_123'))
  .filter((value) => value.includes('@'))
  .unwrapOr(() => '[e-mail]');

Use Result for typed failures

Use Result when you want explicit error payloads.

import { Result } from 'funkcia';
import { TaggedError } from 'funkcia/exceptions';

class InvalidCouponError extends TaggedError('InvalidCouponError') {}

function validateCoupon(code: string) {
  return code.length > 5
    ? Result.ok(code)
    : Result.error(new InvalidCouponError('Coupon code is too short'));
}

Move to async with OptionAsync and ResultAsync

import { OptionAsync } from 'funkcia/option-async';
import { ResultAsync } from 'funkcia/result-async';

declare function readToken(): Promise<string | null>;
declare function fetchUser(token: string): Promise<{ id: string }>;

const token = OptionAsync.try(() => readToken());

const user = token
  .andThen((value) => OptionAsync.fromNullable(value))
  .andThen((value) => OptionAsync.try(() => fetchUser(value)));

const safeUser = ResultAsync.try(() => fetchUser('token'));

Next steps

• Learn do-notation:

  • Option Do Notation

  • Result Do Notation

  • OptionAsync Do Notation

  • ResultAsync Do Notation

• Learn error propagation:

  • Option Error Propagation

  • Result Error Propagation

  • OptionAsync Error Propagation

  • ResultAsync Error Propagation