;;; =======================================
;;; Simple examples, not involving sheets, 
;;;          files, or graphics
;;; =======================================

;;; The factorial function
(bulk-define fact integer integer
     (lambda (x) 
       (expect (>= x 0))
       (cond ((<= x 1) 1)
             (#t (* x (fact (- x 1)))))))


;;; vector inputs
(bulk-define vect-combine 
             ((integer-point 2) (integer-point 2)) 
             (integer-point 2)
    (lambda (x y) (* 2 (+ x y))))


;;; multiple return values
(bulk-define split integer (integer integer)
    (lambda (x) (values x (* 2 x))))


;;; no inputs, returns random value
(bulk-define random-output () real
        (lambda () (random-real 2.0 4.0)))


;;; simple example of a conditional
(bulk-define cond-sqrt integer real
       (lambda (x) (if (> x 3) (sqrt x) x)))

;;; ================================================================
;;; compiler handling of missing values
;;; ================================================================

;;; user specifies nothing:  tests for missing inputs are
;;;   inserted automatically
(bulk-define test (integer integer) integer
  (lambda (x y) (if (< x y) (+ x 1) (* y 2))))

;;; Test explicitly inserted by user (redundant in this case,
;;;   but useful for removing tests from inside loops in other 
;;;   examples).
(bulk-define test (integer integer) integer
  (lambda (x y) 
    (expect (not (missing? x)))
    (if (< x y) (+ x 1) (* y 2))))

;;; Another way to explicitly structure tests at the user level
(bulk-define test (integer integer) (integer integer)
  (lambda (x y) 
    (if (or (missing? x) (missing? y))
	(values (make-missing) (make-missing))
	(values (+ x 1) (* y 2)))))

;;; ================================================================
;;; more complex ones 
;;; ================================================================

;;; a loop which adds the squares of the integers 
;;; between i and b (inclusive)
(bulk-define loop (integer integer) integer
       (lambda (i b)
        (do ((j i (+ j 1)) 
             (sum 0))
            ((> j b) sum)
          (set! sum (+ sum (* j j))))))

;;; Set an integer-grid at all positions without a scan
;;; From Dan's thesis.
(bulk-define without-scan
   ((integer-grid 2 1) integer)
   unspecified
   (lambda (ig value)
     (do ((x 0 (+ x 1)))
	 ((= x 640))
       (do ((y 0 (+ y 1)))
	   ((= y 480))
	 (sample-set! (nearest-sample ig x y) value)))))