Make the successful return value from a match expression be truthy and the failure value false. This avoids an extra method call when checking the result and avoids allocating a new object when a match fails.

#{
fib <- :n {
  if: n < 2 {
    1
  } else: {
    (fib: n-1) + (fib: n-2)
  }
}

main <- {
  print: (string: (fib: 30)) . "\n"
}

}