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allOf / anyOf / noneOf ​

Problem ​

You need to combine multiple predicate functions with AND, OR, or NOR logic — for example building a compound filter without nested && / || chains.

Solution ​

Use allOf, anyOf, or noneOf to compose predicates into a single function.

ts
import { allOf, anyOf, noneOf } from '@vielzeug/arsenal';

const isWorkingAge = allOf<number>(
  (age) => age >= 18,
  (age) => age < 65,
);

isWorkingAge(30); // true
isWorkingAge(70); // false — fails second predicate

const isSpecialAge = anyOf<number>(
  (age) => age === 0,
  (age) => age === 100,
);

isSpecialAge(0); // true
isSpecialAge(50); // false

const noEvens = noneOf<number>((n) => n % 2 === 0);
[1, 2, 3, 4].filter(noEvens); // [1, 3]

Pitfalls ​

  • allOf with zero predicates returns true (vacuous truth).
  • anyOf with zero predicates returns false (vacuous falsity).
  • noneOf with a single predicate is equivalent to logical NOT — use not for that case to signal intent clearly.