;; To run this code, first open interpreter.scm in DrRacket and type (start),
;; then type (load-quietly "examples.txt") at the ==> interpreter prompt.
;;
;;----------------------------------------------------------------------------
;; Examples of BlooP programs

(define procedure "square" (n)
  (block 0 begin
	 (output <= (n * n))))

(define procedure "cube" (n)
  (block 0 begin
	 (output <= (n * n))
	 (output <= (output * n))))

(define procedure "two-to-the-three-to-the" (n)
  (block 0 begin
	 ((cell 0) <= 1)
	 (loop n times
	       (block 1 begin
		      ((cell 0) <= (3 * (cell 0)))))
	 ((cell 1) <= 1)
	 (loop (cell 0) times
	       (block 2 begin
		      ((cell 1) <= (2 * (cell 1)))))
	 (output <= (cell 1))))

(define procedure "factorial" (n)
  (block 0 begin
	 (output <= 1)
	 ((cell 0) <= 1)
	 (loop n times
	       (block 1 begin
		      (output <= (output * (cell 0)))
		      ((cell 0) <= ((cell 0) + 1))))))

(define procedure "even?" (n)
  (block 0 begin
	 (if ((remainder n 2) = 0) then
	     (output <= yes))))

(define procedure "odd?" (n)
  (block 0 begin
	 (if ((remainder n 2) = 1) then
	     (output <= yes))))

(define procedure "prime?" (n)
  (block 0 begin
	 (if (n < 2) then
	     (quit block 0))
	 ((cell 0) <= 2)
	 (loop at most (minus n 2) times
	       (block 1 begin
		      (if ((remainder n (cell 0)) = 0) then
			  (quit block 0))
		      ((cell 0) <= ((cell 0) + 1))))
	 (output <= yes)))

(define procedure "goldbach?" (n)
  (block 0 begin
  	 (if (not (even? n)) then
	     (quit block 0))
	 ((cell 0) <= 2)
	 (loop at most n times
	       (block 1 begin
	       	      (print "testing" (cell 0) "and" (minus n (cell 0)))
		      (if ((prime? (cell 0)) and
			   (prime? (minus n (cell 0)))) then
			  (block 2 begin
				 (output <= yes)
				 (quit block 0)))
		      ((cell 0) <= ((cell 0) + 1))))))