[greggyb]

If something works based on .NET IL, then it works equally well for F# as C#. Both are first class languages in .NET. Anything written in one can be used from the other (though it is often very un-idiomatic without a wrapper). Both compilers generate the same IL.

[pjmlp]

Not really, as there are restrictions, and for example .NET Native didn't handle some of the IL pattern required by F#. This was never fixed, even though there are some kind of workarounds.

F# also has some issues with some IL constructs generated by C#, with features not exposed in F#, like protected, which can be consumed, but not authored.

[greggyb]

I wasn't aware of the issues with .NET Native.

Your second point is exactly what I said, though. F# can consume things written in C#. Whether the F# language team wants to include some specific feature is a different question. C# libraries that use the protected attribute can be used transparently in F#.

They are different languages with a shared runtime. You can't write a computation expression in C#, but an F# library function that is implemented with CEs can still be called from C#.

[pjmlp]

> C# libraries that use the protected attribute can be used transparently in F#.

Only if you don't need to write data types that need to be consumed by said libraries, as to express those types you need C# features.

Another two key examples are the recent trends from .NET team to depend on Roslyn and code generators, both not supported by F#, so the language can't be fully used in such workloads without a little bit of C# glue.

Really, F# might be from Microsoft, but the .NET team handles it as if it was a 3rd party guest language.

[FrustratedMonky]

Yes. Think this is the frustrating part. MS kind of broadcast like it is equal, full language. But .NET doesn't support everything.

I think this is why .NET core doesn't have typeproviders?