Maybe<T> is a simplistic implementation of an option type, much like Optional in Java.

While option types for value types are supported natively in the BCL through Nullable<T>, there is currently no equivalent for reference types. This (very small) library aims to complement the BCL by providing such a type, allowing developers to handle null values more succinctly - namely through Maybe<T>.NoValue.

Maybe's implementation is contained in a single struct.

You can find the reason this implementation was written in this post on my blog.

You can obtain the latest version from NuGet. The NuGet package supports .NET Standard 1.0 through 2.0.

Constructing an option type can be done in several different ways. The first, and most obvious, is simply new-ing an instance:

    var maybe = new Maybe<string>("hello");

However, we can also let the compiler infer the type argument for us, through the use of the various Of methods:

    var maybe = Maybe.Of("hello");

If we're unsure whether the value we're passing to Of is null or not, you can also use OfNullableReferenceType, since Of will throw an ArgumentNullException if its value argument is null.

Whichever way we choose to construct the Maybe<T> instance with, we can always check whether it has a value with maybe.HasValue, and retrieve its value with maybe.Value, if it contains one. Note that if maybe.Value is called on an instance which doesn't contain a value, an InvalidOperationException will be thrown, since there is no sensible way to handle that case without exposing null (which is what we're trying to prevent here in the first place).

For the sake of consistency, it could be desirable to wrap value types in an option type. While this is supported, do keep in mind that Maybe<T> does not get the same special treatment Nullable<T> gets - i.e. Maybe<T> can be boxed, whereas Nullable<T> will never get boxed.

To create a Maybe<T> instance from either a value type or a Nullable<T>, you can use something along the lines of:

    var maybe = Maybe.OfValueType(Guid.Empty);

This code is licensed under the Apache 2.0 license. For a brief summary on what this license entails, please refer to Tldrlegal. Please respect all licenses.

Questions and contributions are very much welcome. When submitting a pull request, please make sure it is accompanied by an issue on the issue tracker, and if a non-trivial change, have been discussed prior to putting in the effort.

When contributing code, please try and adhere to the coding style already present as much as possible. If you are unsure what coding style that is, it is fairly close to the .NET Core coding style.