Enum Never

Represents an uninhabitable type.

Namespace: Maki

Assembly: Maki.dll

Syntax

public enum Never

Examples

Never is impossible to instantiate, thus it can be use to denote absence of a value. The following example shows two use-cases of Never: explicitly showing a method does not return and as a generic type argument to remove the type option.

using Maki;
using System;

namespace Samples
{
    class Program
    {
        // This function never returns
        static Never Fail(string message)
        {
            throw new Exception(message);
        }

        // This function also never returns
        static Never LoopForever()
        {
            while (true)
            { }
        }

        // Assume a generic library method which expects an Either<T, U>
        static void NeedsGenericEither<T, U>(Either<T, U> either)
        {
            // ...
        }

        static void Main(string[] args)
        {
            // We can remove a type from Either by providing Never
            Either<int, Never> either = 42;

            NeedsGenericEither(either);
        }
    }
}