Quick Reference

• allOf / anyOf / noneOf
• assert
• constant
• debounce
• identity
• memo
• not
• once
• pipe
• runAll
• tap
• throttle

Common Patterns

import {
  allOf,
  anyOf,
  assert,
  compareBy,
  constant,
  debounce,
  identity,
  memo,
  noneOf,
  once,
  pipe,
  tap,
  throttle,
} from '@vielzeug/arsenal';

assert(Array.isArray([1, 2, 3]), 'Expected array');

const sortUsers = compareBy<{ name: string; age: number }>({ age: 'desc', name: 'asc' });

const trimUpper = pipe(
  (s: string) => s.trim(),
  (s) => s.toUpperCase(),
);

// allOf: true only when every predicate matches (vacuous truth with zero predicates)
const isWorkingAge = allOf<number>(
  (age) => age >= 18,
  (age) => age < 65,
);

// anyOf: true when at least one predicate matches (vacuous falsity with zero predicates)
const isSpecialAge = anyOf<number>(
  (age) => age === 0,
  (age) => age === 100,
);

// noneOf: true when no predicate matches — single predicate equivalent to logical NOT
const odds = [1, 2, 3, 4].filter(noneOf((n: number) => n % 2 === 0));

const expensive = memo((n: number) => n * n);
const identityValue = identity('ok');
const alwaysFive = constant(5);
const observed = tap(42, (value) => console.log('tap', value));
const initOnce = once(() => console.log('init'));
const onInput = debounce((q: string) => console.log(q), 250);
const onScroll = throttle(() => console.log('scroll'), 100);

console.log(
  sortUsers,
  trimUpper('  alice  '),
  expensive(4),
  identityValue,
  alwaysFive(),
  odds,
  observed,
  isWorkingAge(32, 0, [32]),
  isSpecialAge(0, 0, [0]),
  initOnce(),
  onInput,
  onScroll,
);