(define bubble-sort 
    X -> (bubble-again-perhaps (bubble X) X))

(define bubble 
  [ ] -> [ ]  
  [X] -> [X]  
  [X Y | Z] -> [Y | (bubble [X | Z])] 		where (prior? Y X)
  [X Y | Z] -> [X | (bubble [Y | Z])])

(define bubble-again-perhaps  
   X X -> X  
   X _ -> (bubble-sort X))

(define prior?
   Name1 Name2 -> (string< (surname Name1) (surname Name2)))

(define surname
   Name -> (surname-help Name ""))

(define surname-help
   "" Surname -> Surname
   (@s S Name) _ -> (surname-help Name "")	where (whitespace? S)
   (@s S Name) Surname ->  (surname-help Name (cn Surname S))) 

(define whitespace?
   S -> (let N (string->n S) (element? N [9 10 13 32])))

 (define string<
   (@s S _) (@s S# _) -> true 	where (< (string->n S) (string->n S#))
   (@s S Ss) (@s S Ss#) -> (string< Ss Ss#)
   "" (@s _ _) -> true
   _ _ -> false)

(bubble-sort ["Rudolf Carnap"  "Richard Dawkins" 
                              "John Backus"  "Harold Abelson" ])