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Function: fromPredicate()

fromPredicate<T, E>(predicate, error): Validator<T, T, E>

Defined in: validation/constructors/index.ts:101

Creates a validator from a predicate function.

If the predicate returns true, returns Valid with the value. If the predicate returns false, returns Invalid with the error.

Type Parameters​

T​

T

E​

E

Parameters​

predicate​

Predicate<T>

Function that tests the value

error​

E

Error to return when predicate fails

Returns​

Validator<T, T, E>

A validator function

Example​

import { gt } from 'receta/predicate'

// Simple predicate validator
const isPositive = fromPredicate(
  (n: number) => n > 0,
  'Must be positive'
)
isPositive(5) // => Valid(5)
isPositive(-1) // => Invalid(['Must be positive'])

// Using predicate builders
const isAdult = fromPredicate(
  gt(18),
  'Must be 18 or older'
)

// Real-world: Email validation
const isEmail = fromPredicate(
  (s: string) => /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(s),
  'Invalid email format'
)

See​

fromPredicateWithError - for dynamic error messages