A null-free optional value library for .NET.
- An optional value is represented as the base type Opt<T>
- Present values are represented as the derived type Opt<T>.Some
- Missing values are represented as the static property Opt<T>.None
See the Examples Tests for more on how to use Opt.
- NuGet packages are available on NuGet.org
- Embedded debug symbols
- Source Link enabled
- NuGet packages from CI builds are available on the libanvl GitHub feed
- Immutable
- Use Opt<T> instead of T? for optional values
- Implicit conversion from T to Opt<T>
- Opts of IEnumerable<T> are iterable
- Deep selection of properties in complex objects
- SomeOrEmpty() for string and enumerables
- SomeOrDefault() for any type
- Change to a null with SomeOrNull()
- Explicitly opt-in to exceptions with Unwrap()
- Cast inner value to compatible type with Cast()
class Car
{
public string Driver { get; set;}
}
public void AcceptOptionalValue(Opt<Car> optCar, Opt<string> optName)
{
if (optCar is Opt<Car>.Some someCar)
{
someCar.Value.Driver = optName.SomeOrDefault("Default Driver");
}
if (optCar.IsNone)
{
throw new Exception();
}
// or use Unwrap() to throw for None
Car bcar = optCar.Unwrap();
}
public void RunCarOperations()
{
var acar = new Car();
AcceptOptionalValue(acar, "Rick");
Car? nocar = null;
AcceptOptionalValue(nocar.WrapOpt(), None.String)
// use Select to project to an Opt of an inner property
Opt<string> driver = acar.Select(x => x.Driver);
}
public void OptsOfEnumerablesAreIterable<T>(Opt<List<T>> optList)
{
// if optList is None, the enumerable is empty, not null
foreach (T item in optList)
{
Console.WriteLine(item);
}
// this is equivalent
foreach (T item in optList.SomeOrEmpty())
{
Console.WriteLine(item);
}
}