eiriklv/unexceptional

Exception safe functions and promises by converting thrown errors to values (like Go and Lua)

Unexceptional

Exception safe functions and promises by converting thrown errors to values (like Go and Lua). See this gist for background.

NOTE: This meant initially developed for usage together with async/await and function*/yield, so all results are converted to promises (see the source in index.js for more info).

Usage examples

Safe(r) functions:

const { safeFunction } = require('unexceptional');

function iThrowThingsSometimes(val, shouldThrow) {
  if (shouldThrow) {
    throw new Error('Something went wrong');
  } else {
    return val;
  }
}

const iDontThrowAnyMore = safeFunction(iThrowThingsSometimes);

async function main() {
  const [error, result] = await iDontThrowAnyMore(50);
  // error === undefined
  // result === 50

  if (error) {
    // handle error as a value or ignore
  }

  const [error2, result2] = await iDontThrowAnyMore(50, true);
  // error2 === Error('Something went wrong');
  // result2 === undefined

  if (error2) {
    // handle error as a value or ignore
  }
}

main();

Safe(r) promises:

const { safePromise } = require('unexceptional');

function iRejectSometimes(val, shouldReject) {
  return new Promise(function(resolve, reject) {
    if (shouldReject) {
      reject(new Error('Something went wrong'));
    } else {
      resolve(val);
    }
  });
}

async function main() {
  const [error, result] = await safePromise(iRejectSometimes(50));
  // error === undefined
  // result === 50

  if (error) {
    // handle error as a value or ignore
  }

  const [error2, result2] = await safePromise(iRejectSometimes(50, true));
  // error2 === Error('Something went wrong');
  // result2 === undefined

  if (error2) {
    // handle error as a value or ignore
  }
}