lemper on Compile-Time Checked Truth Tables

Comment on Compile-Time Checked Truth Tables

good thing c# supports pattern match too. just this morning, I wrote something like this

    var thing = (enumA, enumB) switch
    {
        (EnumA.A,EnumB.A) => DoStuff(), 
        _ => throw new Exception(), 
    }

suffice to say, c# is pretty ok, coming from ml family.

KineticLensman 3y

Rust's match is pretty cool as well. Here's Fizzbuzz, lifted from [0]

  match (i % 3 == 0, i % 5 == 0) {
      (false, false)  =>  {  },
      (true, true)    =>  { FizzBuzz },
      (true, false)   =>  { Fizz },
      (false, true)   =>  { Buzz }
  }

I'm moving from C# to Rust at the moment and really enjoying it, especially now that I (almost) understand the borrow checker

[0] https://stackoverflow.com/questions/43896431/c-sharp-equival...

jsmith45 3y

As you hopefully know, the modern C# equivalent is not bad either, especially with top level statements and implicit global usings (The following is the whole program):

    foreach (var i in Enumerable.Range(1,100))
    {
        Console.WriteLine(
            (i%3==0,i%5==0) switch
            {
                (true, true) => "FizzBuzz",
                (true, _) => "Fizz",
                (_, true) => "Buzz",
                (_, _) => $"{i}"
            }
        );
    }

This is so much nicer than what was possible back when the linked question was asked.

recursive 3y

It gets a bit nicer still.

    (i%3,i%5) switch {
        (0, 0) => "FizzBuzz",
        (0, _) => "Fizz",
        (_, 0) => "Buzz",
        (_, _) => i
    }

recursive 3y

Can you match to (i % 3, i % 5) instead?

Philpax 3y

You can, yes: https://play.rust-lang.org/?version=stable&mode=debug&editio...

Smaug123 3y

Enums are a bit leaky, though, because C# enums can just have any old `int` chucked into them, so you really do need the final arm of the `match`. `(EnumA)100` will compile just fine!

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