narrow (method)

narrow

• narrow<U>(_guard): Opt<U>

• Narrows type inside Opt using given type guard.

  Type Parameters

  • U

  Parameters

  • _guard: ((value) => value is U)

    • • (value): value is U

      • Parameters

        • value: any

        Returns value is U

  Returns Opt<U>

  Example

  some('1' as string | number).narrow(isString) // Some('1'): Opt<string>
  some(1 as string | number).narrow(isString) // None: Opt<string>
  

  See

  narrow