The Next Step for Generics

Re:The Next Step for Generics by pwm on Wednesday June 17, 2020 @04:33AM (#23549173)

There are expressive type systems around, it’s the industry at large that needs to use them more and educate future generations on why these are useful tools. I 100% agree that spending 2 days on that task is lunacy. But imagine if youcould do it instantly with 0 ceremony. At that point it would 100% worth your while.

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Re:The Next Step for Generics by DaiPlusPlus on Wednesday June 17, 2020 @09:23AM (#23551054)

So, part of those 2 days was spent toying with Roslyn code-generation to try to re-implement C++ templates in C# - but I ran out of time and reverted back to using T4.

The .NET CLI itself places limits on what .NET-based languages can actually do: for example, structural-typing at method boundaries in CIL is only possible by having the compiler generate build-time adapter classes and interfaces - which means that methods accepting structural-types can’t be easily called by non-strucutural-typing-aware languages. The CLI also imposes single-inheritance - so a .NET language cannot implement multiple inheritance at all - and because non-virtual calls cannot be intercepted at all (without hacks like abusing .NET Remoting’s special-cases in the CLR) it’s not possible to have a “every call is virtual” system like Java’s in the CLR (note to self: find out how J# did it). Implementing Go-style composition is hamstrung by the fact we can’t patch the vtable at runtime either (reified vtables would be nice...).

I dare say it - but I think 2020 marks the decline of C# and the CLR because we’re held-back by decisions made over 15 years ago. .NET 5 isn’t showing any sign of significant improvements to the CLR’s type system or fundamental concepts.

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