(define-syntax for
  (syntax-rules (:)
    [(_ (init : test : update) body ...)
     (begin init
	    (let loop ()
	      (if test
		  (begin body ... update (loop)))))]))


(define-syntax return-first
  (syntax-rules ()
    [(_) (begin)]
    [(_ e1 e2 ...)
     (let ([temp e1])
       e2 ...
       temp)]))