Polymorphic Numerics on .Net and In C#

Question

It\'s a real shame that in .Net there is no polymorphism for numbers, i.e. no INumeric interface that unifies the different kinds of numerical types such as bool, byte, uint

Answer 1

The csharp language team is already looking into this. If you want a view onto the future of type classes in C# start reading at

https://github.com/dotnet/csharplang/issues/164

It seems to have the support of Mads Torgesson so it's not just a random post by a wandering Haskell fanboy.

The example given of a typeclass or shape in C# land is

public shape SGroup<T>
{
    static T operator +(T t1, T t2);
    static T Zero { get; }
}

notice this is not like an interface. It is declaring static method that belong to SGroup. Read on for more details and discussion.

Answer 2

If you plan to use C# 4.0 then you can easily simulate generic mathematical operations using dynamic. Here is an example of a simple addition function (for more information see this blog):

public static T Add<T>(T a, T b) {
  dynamic ad = a;
  dynamic bd = b;
  return ad + bd;
}

I haven't played with this, so I can't say much about the performance. There will certainly be some performance price for using dynamic, but I think the DLR should be able to do very effective optimizations if you'll invoke the function multiple times. In fact, I won't be surprised if it had similar performance profile as Generic Operators mentioned above.

Answer 3

Someone has already gone to the effort of writing something which may solve your delemma. It's called Generic Operators, and is available in the Miscellaneous Utility Library.