Could F# type providers be incorporated in C#

Question

The cool new F# 3.0 feature type providers can be used to bridge the mismatch between F# data types or classes and data source structures like XML or WSDL. However this mismatch is also a challenge in other .NET languages like C#.

I'd like to use the F# 3.0 providers in C# code. How can I do this, if at all? Further, if we cannot, what would a C# implementation need to be able to use them?

Answer 1

I think @kvb gives a good overview of some of the technical difficulties. I agree type inference would be problematic - you would be basically limited to using provider generated types locally, similarly to anonymous types. I think C# might come with something similar in Roslyn, but I doubt it will be as elegantly and smoothly integrated as in F# (where type providers are actually language feature and not just tool).

To answer your two specific questions:

[How can I] use the F# 3.0 providers in C# code?

The F# type providers are really only understood by F# compiler, so you'll need to use them from F#. For generative type providers (SQL, Entities, WSDL, config files), you can reference the provider from F# and use the generated types from C# projects.

For erasing type providers you won't be able to do this, because the types do not really exist and only F# can see them. So the best option is to write your processing code in F# and return results as collections of records or other types that are easily consumed from C#.

What would a C# implementation need to be able to use them?

I could, of course, just say "C# would have to support type providers!", but here are some more thoughts. Type providers are just .NET assemblies and they do not use any F#-specific types. The ITypeProvider interface could be consumed by any .NET language including C#, so if C# designers wanted, they could reuse all the great providers already built for F#.

So, submit this suggestion to the C# user voice or advocate it elsewhere (or convince the Mono team to implement this!) and perhaps it will be added in C# (vNext + 1 + ...). For now, you'll only get all the benefits in F#.