Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Official proposal for Type Unions in C#

github.com

Post reply on HN
Print view View original

21–30 of 315 posts

Re: Official proposal for Type Unions in C#

#21

Post by fluoridation »

wk_end wrote: post #12
ComputerGuru wrote: post #8

Every time the question of preferred programming languages comes up, I'm usually in the extreme minority with my preferences being Rust (for small/fast) and C# (for productive and easy, where GC is acceptable), a combination that doesn't seem to appeal to too many people. But for the projects that fall right about in the middle where it could go either way and I could see either language working, I almost always pick…

Instead of C#, why not F#? You get proper ADTs among many other great features, but you still get all the utility of the .NET ecosystem.

I get the feeling F# is a second-class citizen in the ecosystem. How likely is it (or is it at all possible) that I'm going to run into some library that doesn't work with F#?

Re: Official proposal for Type Unions in C#

#22

Post by mlinhares »

ComputerGuru wrote: post #8

Every time the question of preferred programming languages comes up, I'm usually in the extreme minority with my preferences being Rust (for small/fast) and C# (for productive and easy, where GC is acceptable), a combination that doesn't seem to appeal to too many people. But for the projects that fall right about in the middle where it could go either way and I could see either language working, I almost always pick…

C# is great, likely the best mainstream programming language nowadays, but its in the hands of microsoft and microsoft didn't really care much about building a community or getting it to work natively in other OSes/toolchains.

Its a shame, they even had a second change when Oracle bought sun and no one knew what was going to happen with Java, but fumbled that as well.

Re: Official proposal for Type Unions in C#

#24

Post by hnrodey »

mlinhares wrote: post #22
ComputerGuru wrote: post #8

Every time the question of preferred programming languages comes up, I'm usually in the extreme minority with my preferences being Rust (for small/fast) and C# (for productive and easy, where GC is acceptable), a combination that doesn't seem to appeal to too many people. But for the projects that fall right about in the middle where it could go either way and I could see either language working, I almost always pick…

C# is great, likely the best mainstream programming language nowadays, but its in the hands of microsoft and microsoft didn't really care much about building a community or getting it to work natively in other OSes/toolchains. Its a shame, they even had a second change when Oracle bought sun and no one knew what was going to happen with Java, but fumbled that as well.

Come again?

Re: Official proposal for Type Unions in C#

#25

Post by msk-lywenn »

mlinhares wrote: post #22
ComputerGuru wrote: post #8

Every time the question of preferred programming languages comes up, I'm usually in the extreme minority with my preferences being Rust (for small/fast) and C# (for productive and easy, where GC is acceptable), a combination that doesn't seem to appeal to too many people. But for the projects that fall right about in the middle where it could go either way and I could see either language working, I almost always pick…

C# is great, likely the best mainstream programming language nowadays, but its in the hands of microsoft and microsoft didn't really care much about building a community or getting it to work natively in other OSes/toolchains. Its a shame, they even had a second change when Oracle bought sun and no one knew what was going to happen with Java, but fumbled that as well.

This comment feels like it's been written 20 years ago. C# runs natively anywhere and this has been true for at least a decade.

Re: Official proposal for Type Unions in C#

#26

Post by DaiPlusPlus »

wk_end wrote: post #12
ComputerGuru wrote: post #8

Every time the question of preferred programming languages comes up, I'm usually in the extreme minority with my preferences being Rust (for small/fast) and C# (for productive and easy, where GC is acceptable), a combination that doesn't seem to appeal to too many people. But for the projects that fall right about in the middle where it could go either way and I could see either language working, I almost always pick…

Instead of C#, why not F#? You get proper ADTs among many other great features, but you still get all the utility of the .NET ecosystem.

The benefits of F# only really apply when using a 100% F# codebase.

Try doing WinForms in F#...

Re: Official proposal for Type Unions in C#

#27

Post by nightski »

fluoridation wrote: post #21
wk_end wrote: post #12

Earlier quoted context omitted.

Instead of C#, why not F#? You get proper ADTs among many other great features, but you still get all the utility of the .NET ecosystem.

I get the feeling F# is a second-class citizen in the ecosystem. How likely is it (or is it at all possible) that I'm going to run into some library that doesn't work with F#?

None, it's a CLR after all. That said many libraries may not utilize the best features F# has to offer.

Re: Official proposal for Type Unions in C#

#28

Post by DaiPlusPlus »

mlinhares wrote: post #22
ComputerGuru wrote: post #8

Every time the question of preferred programming languages comes up, I'm usually in the extreme minority with my preferences being Rust (for small/fast) and C# (for productive and easy, where GC is acceptable), a combination that doesn't seem to appeal to too many people. But for the projects that fall right about in the middle where it could go either way and I could see either language working, I almost always pick…

C# is great, likely the best mainstream programming language nowadays, but its in the hands of microsoft and microsoft didn't really care much about building a community or getting it to work natively in other OSes/toolchains. Its a shame, they even had a second change when Oracle bought sun and no one knew what was going to happen with Java, but fumbled that as well.

> but its in the hands of microsoft and microsoft didn't really care much about building a community or getting it to work natively in other OSes/toolchains.

That statement was true - until 2016. Times change, Microsoft changed.

Re: Official proposal for Type Unions in C#

#29

Post by louthy »

wackro wrote: post #18

What would the rough timeframe be for seeing adoption of this into the language? I was considering introducing the OneOf library into our codebase, but if this is < a year or so away it might not be worth the effort.

You won't be able to leverage C#'s pattern-matching effectively with a library.

Really though, you don't need a library to do sum-types in C#:

It's best to just use records for now:

    public abstract record Maybe
    {
        private Maybe() { }

        public sealed record Just(A Value) : Maybe;
        public sealed record Nothing : Maybe;
    }
The private constructor and sealed case-types stops anybody else deriving from `Maybe`, so the type is effectively closed and finite.

You can then construct like so:

    var mx = new Maybe.Just(123);
    var my = new Maybe.Nothing();
Then you can use the pattern-matching:

   var r = mx switch
   {
      Maybe.Just (var x) => x,
      Maybe.Nothing      => 0
   };
Of course, we don't get exhaustiveness checking, that'll have to wait for the proper sum-types (although the compiler does some pretty good work on this right now); but until then this is the most expressive and powerful way of doing sum-types in C#.

And, if you want a load of pre-built ones, then my library language-ext will help [1]

[1] https://github.com/louthy/language-ext/

Re: Official proposal for Type Unions in C#

#30

Post by pathartl »

DaiPlusPlus wrote: post #28
mlinhares wrote: post #22

Earlier quoted context omitted.

C# is great, likely the best mainstream programming language nowadays, but its in the hands of microsoft and microsoft didn't really care much about building a community or getting it to work natively in other OSes/toolchains. Its a shame, they even had a second change when Oracle bought sun and no one knew what was going to happen with Java, but fumbled that as well.

> but its in the hands of microsoft and microsoft didn't really care much about building a community or getting it to work natively in other OSes/toolchains. That statement was true - until 2016. Times change, Microsoft changed.

Yeah, really. I'm distributing a .NET 8 app across Windows, macOS, Linux and x64/arm.
Post reply on HN