[Udo]

Ah, I'm so dense! Sure, there is also "math.pi" as a built-in for that. (And I fixed this grave rounding error)

I also discovered a scope problem with the recursion example you gave. Turns out, there is (of course) a major bug in there, thanks for discovering that. It's about the visibility of the "factorial" symbol itself, so the workaround is for now:

  factorial = { n |
    factorial = outer.factorial;
    if(n == 0) {
      1
    } {
      n * (factorial (n - 1))
    } 
  };
  println (factorial 5); 

At least, until I restart the service (which I don't want to do while everyone is potentially using the tutorial).