C# library for unions. Similar to OneOf, with a few conceptual changes.

• Better handling of nullable reference types
• Change methods to match C# idioms, rather than adopting F# idioms.

Examples

private static void Main()
{
ReadFileText("C:\\Path\\to\\file.txt").Switch(
_ => Console.WriteLine($"File doesn't exist."),
error => Console.WriteLine($"Error: {error.Value}"),
contents => Console.WriteLine($"File contents: {contents}")
);
}
private static Union<None, Error<string>, string> ReadFileText(string path)
{
try
{
if (File.Exists(path) == false)
return new None();
return File.ReadAllText(path);
}
catch (Exception e)
{
return new Error<string>(e.Message);
}
}

Nulls

Null values are not allowed.

If you have the need to return a null value, I suggest a different pattern - using the None type instead of returning null. See the above example - instead of returning null, Union.None is returned. Thus, all other options are guarenteed to not be null.