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Function: unwrapOrElse()

Call Signature​

unwrapOrElse<T, E>(validation, fn): T

Defined in: validation/unwrap/index.ts:151

Extracts the value from a Valid validation or computes a default from errors.

Type Parameters​

T​

T

E​

E

Parameters​

validation​

Validation<T, E>

The validation to unwrap

fn​

(errors) => T

Function that takes errors and returns a default value

Returns​

T

The value from Valid, or the computed default

Example​

// Data-first
unwrapOrElse(valid(42), () => 0)
// => 42

unwrapOrElse(invalid(['error1', 'error2']), (errors) => {
  console.error('Validation failed:', errors)
  return 0
})
// Logs errors and returns 0

// Data-last (in pipe)
pipe(
  validateInput(input),
  unwrapOrElse((errors) => {
    reportErrors(errors)
    return fallbackValue
  })
)

// Real-world: Log errors and return default
const getConfig = (raw: unknown) =>
  pipe(
    validateConfig(raw),
    unwrapOrElse((errors) => {
      logger.error('Config validation failed', { errors })
      return defaultConfig
    })
  )

// Real-world: Create error report
const processForm = (data: FormData) =>
  pipe(
    validateForm(data),
    unwrapOrElse((errors) => {
      showNotification({
        type: 'error',
        message: `Validation failed with ${errors.length} errors`
      })
      return emptyForm
    })
  )

See​

  • unwrapOr - for a static default value
  • match - for comprehensive error handling

Call Signature​

unwrapOrElse<T, E>(fn): (validation) => T

Defined in: validation/unwrap/index.ts:155

Extracts the value from a Valid validation or computes a default from errors.

Type Parameters​

T​

T

E​

E

Parameters​

fn​

(errors) => T

Function that takes errors and returns a default value

Returns​

The value from Valid, or the computed default

(validation): T

Parameters​

validation​

Validation<T, E>

Returns​

T

Example​

// Data-first
unwrapOrElse(valid(42), () => 0)
// => 42

unwrapOrElse(invalid(['error1', 'error2']), (errors) => {
  console.error('Validation failed:', errors)
  return 0
})
// Logs errors and returns 0

// Data-last (in pipe)
pipe(
  validateInput(input),
  unwrapOrElse((errors) => {
    reportErrors(errors)
    return fallbackValue
  })
)

// Real-world: Log errors and return default
const getConfig = (raw: unknown) =>
  pipe(
    validateConfig(raw),
    unwrapOrElse((errors) => {
      logger.error('Config validation failed', { errors })
      return defaultConfig
    })
  )

// Real-world: Create error report
const processForm = (data: FormData) =>
  pipe(
    validateForm(data),
    unwrapOrElse((errors) => {
      showNotification({
        type: 'error',
        message: `Validation failed with ${errors.length} errors`
      })
      return emptyForm
    })
  )

See​

  • unwrapOr - for a static default value
  • match - for comprehensive error handling