3 ms·

I have the same objection but coming from the other side. The mainstream languages used to have pervasive mutation and side-effects. Now they have pervasive m

by mrkeen 2y ago

I have the same objection but coming from the other side. The mainstream languages used to have pervasive mutation and side-effects. Now they have pervasive mutation and side-effects with lambdas. But my question is: what is missing from the OO side? What would it take for C# and/or others to "do OO well"?

LAC-Tech 2y ago
To be clear I don't really come from "the other side". I very much enjoy and like functional programming. But again, that's what F# is for, right? If we push the state of the art in another directrion, the whole landscape benefits more - because I think we both agree C# is never going to be a better FP language than F#. As for what C# could do better, the OO solution to the problem pattern matching solves is multiple dispatch - with single dispatch languages you need things like the visitor pattern. Making that a first class part of C# would be fantastic. https://shawnhargreaves.com/blog/visitor-and-multiple-dispatch-via-c-dynamic.html https://shawnhargreaves.com/blog/visitor-and-multiple-dispat...
lyu07282 2y ago
> What would it take for C# and/or others to "do OO well"? Multiple inheritance. (j/k)
- LAC-Tech 2y ago
  Unironically this. Having "interfaces" and "abstract classes" is just a kludge, multiple inheritance covers all of this with one language construct. The "diamond problem" is a C++ issue, every other language solved it.
  - lyu07282 2y ago
    I think they solved the problem by not supporting multiple inheritance, instead supporting interfaces and/or traits. But also "composition over inheritance" pretty much won, thankfully imho.
    - hakanderyal 2y ago
      Mixins via inheritance is a sweet pattern that I miss in C# sometimes.
      - mastry 2y ago
        C# has default interface implementations now, that can be used to create mixins... https://learn.microsoft.com/en-us/dotnet/csharp/advanced-topics/interface-implementation/mixins-with-default-interface-methods https://learn.microsoft.com/en-us/dotnet/csharp/advanced-top...
        hakanderyal 2y ago
        Yeah I sometimes use them but they don’t cover all the cases. I’m waiting for roles/extensions to see if I can achieve a similar result. https://github.com/dotnet/csharplang/discussions/5496 https://github.com/dotnet/csharplang/discussions/5496
    - LAC-Tech 2y ago
      https://en.wikipedia.org/wiki/Multiple_inheritance#Mitigation https://en.wikipedia.org/wiki/Multiple_inheritance#Mitigatio... CLOS and Ocaml figured it out
      - freilanzer 2y ago
        When in doubt look to CLOS.
  - consteval 2y ago
    The "diamond problem" isn't a C++ problem. C++ solved it with virtual inheritance. Also C++ has exactly what you want. No interfaces, multiple inheritance. People don't utilize it unless it's a GUI lib.

by mrkeen 2y ago

LAC-Tech 2y ago

To be clear I don't really come from "the other side". I very much enjoy and like functional programming. But again, that's what F# is for, right? If we push the state of the art in another directrion, the whole landscape benefits more - because I think we both agree C# is never going to be a better FP language than F#. As for what C# could do better, the OO solution to the problem pattern matching solves is multiple dispatch - with single dispatch languages you need things like the visitor pattern. Making that a first class part of C# would be fantastic. https://shawnhargreaves.com/blog/visitor-and-multiple-dispatch-via-c-dynamic.html https://shawnhargreaves.com/blog/visitor-and-multiple-dispat...

lyu07282 2y ago

> What would it take for C# and/or others to "do OO well"? Multiple inheritance. (j/k)

LAC-Tech 2y ago
Unironically this. Having "interfaces" and "abstract classes" is just a kludge, multiple inheritance covers all of this with one language construct. The "diamond problem" is a C++ issue, every other language solved it.
- lyu07282 2y ago
  I think they solved the problem by not supporting multiple inheritance, instead supporting interfaces and/or traits. But also "composition over inheritance" pretty much won, thankfully imho.
  - hakanderyal 2y ago
    Mixins via inheritance is a sweet pattern that I miss in C# sometimes.
    - mastry 2y ago
      C# has default interface implementations now, that can be used to create mixins... https://learn.microsoft.com/en-us/dotnet/csharp/advanced-topics/interface-implementation/mixins-with-default-interface-methods https://learn.microsoft.com/en-us/dotnet/csharp/advanced-top...
      - hakanderyal 2y ago
        Yeah I sometimes use them but they don’t cover all the cases. I’m waiting for roles/extensions to see if I can achieve a similar result. https://github.com/dotnet/csharplang/discussions/5496 https://github.com/dotnet/csharplang/discussions/5496
  - LAC-Tech 2y ago
    https://en.wikipedia.org/wiki/Multiple_inheritance#Mitigation https://en.wikipedia.org/wiki/Multiple_inheritance#Mitigatio... CLOS and Ocaml figured it out
    - freilanzer 2y ago
      When in doubt look to CLOS.
- consteval 2y ago
  The "diamond problem" isn't a C++ problem. C++ solved it with virtual inheritance. Also C++ has exactly what you want. No interfaces, multiple inheritance. People don't utilize it unless it's a GUI lib.