stepanvanzuriak / one.macro

one.macro

Macros collection

guard

import { guard } from 'one.macro';

function earlyReturn(value, flag) {
  guard(value || flag, 'Required');
  guard(value > 12);

  return 'Fine';
}

earlyReturn(10); // returns undefined
earlyReturn(100); // returns "Fine"
earlyReturn(); // returns "Required"

overload

import { overload } from 'one.macro';

const greeting = overload(
  (name = 'John') => 'Hello, John!',
  (name = 'World') => 'Hello, World!',
  (name, lastName) => `Hello, ${name} ${lastName}!`,
  (any) => 'Hello anyway!',
);

greeting('John'); // Hello, John!
greeting('World'); // Hello, World!
greeting('Matt', 'Doe'); // Hello, Matt Doe!
greeting(42); // Hello anyway!

Custom when guard example

import { overload, when } from 'one.macro';

const isJson = (kind, someStatus) => kind === 'JSON' && someStatus > 100;
const isCSV = (kind, someStatus) => kind === 'CSV' && someStatus > 150;
const statusGuard = (_, someStatus) => someStatus < 0;

const dummyIdentifier = overload(
  when(isJson, () => 'Yep, JSON'),
  when(isCSV, () => 'Yep, CSV'),
  when(statusGuard, () => 'Status code error'),
  (any, someStatus) => 'Unknown',
  (any) => 'Status code required',
);

dummyIdentifier('JSON', 110); // Yep, JSON
dummyIdentifier('CSV', 160); // Yep, CSV
dummyIdentifier('JSON', -100); // Status code error
dummyIdentifier('XML'); // Status code required
dummyIdentifier('XML', 100); // Unknown

Array sum example

import { overload, when } from 'one.macro';

const sumList = overload(
  (list = [], acc) => acc,
  ([head, ...tail], acc) => sumList(tail, head + acc),
);

sumList([1, 2, 3], 0); // 6
sumList([1, 2, 3], 6); // 12
sumList([], 100); // 100