[klauserc]

C# pattern matching gets very close. I think C# can do everything except for their last example ("splitting conditional prefixes in arbitrary places"). One of the things I miss when switching to Rust.

    if foo(args)
        == 0 then "null"
        |> abs
            > 100 then "large"
            < 10 then "small"
            else "medium"

That last syntax took me a while to parse in the paper, but I can imagine numerous places in our everyday code where such syntax would more concisely capture intent.

[lptk]

Genuine question, as I'm not up to date with C#'s recent developments: can C# do this?

    if e is
      ...
      Lit(value)
        and Map.find_opt(value) is Some(result)
        then Some(result)
      ...

where the `...` may include many cases and may contain other Lit cases.

Or this variation:

      ...
      Lit(value)
        and Map.find_opt(value) is Some(result)
        and computation(result) is
          Left(a)  then ...
          Right(b) then ...
      ...

[tobbebex]

Oh but C# can do even those: https://learn.microsoft.com/en-us/dotnet/csharp/language-ref...

[plaguuuuuu]

I'm wondering if you could use Roslyn to implement your snippet's syntax anyway.