;; short version
; note: once you use one inline colon, all the following forms on that
; line will get closed at the end of the line

define : factorial n
  if : zero? n
    . 1
    * n : factorial : - n 1

display : factorial 5 


;; more vertical space, less colons
define : factorial n
  if : zero? n
    . 1
    * n 
      factorial 
        - n 1

display : factorial 5