[lachlan-sneff]

That code in the comment above isn't actually rust. It's a lisp, I believe.

In Rust, you'd write something more like:

  fn f(x: &[i32]) -> bool {
      match x {
          [x, y, _] if x == y => true,
          _ => false,
      }
  }

[steveklabnik]

... and you could write

  fn f(x: &[i32]) -> bool {
      x.len() == 3 && x[0] == x[1]
  }

if you wanted. Honestly, I probably would.