Refinements

Refinements are standalone functions that wrap an existing validator to add a constraint. They are the building blocks used internally by validator methods like .url() and .min().

Independent Refinements

These functions are exported from @ctroenv/core for cases where you want to apply a refinement to a custom validator.

url

function url(): <T extends string>(v: Validator<T>) => Validator<T>

Wraps a string validator to require a valid URL:

import { url, string } from "@ctroenv/core"

const myUrlValidator = url()(string().min(1))

email

function email(): <T extends string>(v: Validator<T>) => Validator<T>

Wraps a string validator to require a valid email format.

regex

function regex(pattern: RegExp, message?: string): <T extends string>(v: Validator<T>) => Validator<T>

Wraps a string validator to require a regex match.

min

function min<N extends number>(limit: N): {
  <T extends string>(v: Validator<T>): Validator<T>
  <T extends number>(v: Validator<T>): Validator<T>
}

Wraps a string or number validator to require a minimum length/value.

• For strings: checks value.length >= limit
• For numbers: checks value >= limit

max

function max<N extends number>(limit: N): {
  <T extends string>(v: Validator<T>): Validator<T>
  <T extends number>(v: Validator<T>): Validator<T>
}

Wraps a string or number validator to require a maximum length/value.

• For strings: checks value.length <= limit
• For numbers: checks value <= limit

port

function port(): <T extends number | string>(v: Validator<T>) => Validator<T>

Wraps a number or string validator to require a valid port (1-65535).

integer

function integer<T extends number>(): (v: Validator<T>) => Validator<T>

Wraps a number validator to require an integer value.

When to Use Refinements vs Methods

In most cases, you should use the type-specific methods:

string().url()       // ✅ Preferred
number().int()       // ✅ Preferred

Standalone refinements are useful when building custom validator factories or when you need to apply a refinement that isn't available as a method:

import { url, createValidator, applyChain } from "@ctroenv/core"

const myUrlValidator = applyChain(
  createValidator<string>(
    (input, context) => { /* custom parsing */ },
    { typeLabel: "url" },
  ),
)

// Apply the URL refinement
const validated = url()(myUrlValidator)