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Type Alias: Predicate()<T>

Predicate<T> = (value) => boolean

Defined in: predicate/types.ts:25

A function that takes a value and returns a boolean.

Predicates are used for filtering, validation, and type narrowing. They can be composed using combinators like and, or, and not.

Type Parameters​

T​

T

The type of value the predicate tests

Parameters​

value​

T

Returns​

boolean

Example​

// Simple predicate
const isPositive: Predicate<number> = (n) => n > 0

// Type-narrowing predicate
const isString: Predicate<unknown> = (value): value is string =>
  typeof value === 'string'