(import (srfi 25))

(define-syntax dotimes
  (syntax-rules ()
    ((_ (i n) body ...)
     (do ((i 0 (+ i 1)))
         ((>= i n))
       body ...))))


(define (pascal-upper n)
  (let ((p (make-array (shape 0 n 0 n) 0)))
    (dotimes (i n)
      (array-set! p 0 i 1))
     (dotimes (i (- n 1))
       (dotimes (j (- n 1))
         (array-set! p (+ 1 i) (+ 1 j)
                     (+ (array-ref p i j)
                        (array-ref p (+ 1 i) j)))))
     p))

(define (pascal-lower n)
  (let ((p (make-array (shape 0 n 0 n) 0)))
    (dotimes (i n)
      (array-set! p i 0 1))
     (dotimes (i (- n 1))
       (dotimes (j (- n 1))
         (array-set! p (+ 1 i) (+ 1 j)
                     (+ (array-ref p i j)
                        (array-ref p i (+ 1 j))))))
     p))
(define (pascal-symmetric n)
  (let ((p (make-array (shape 0 n 0 n) 0)))
    (dotimes (i n)
      (array-set! p i 0 1)
      (array-set! p 0 i 1))
     (dotimes (i (- n 1))
       (dotimes (j (- n 1))
         (array-set! p (+ 1 i) (+ 1 j)
                     (+ (array-ref p (+ 1 i) j)
                        (array-ref p i (+ 1 j))))))
     p))


(define (print-array a)
  (let ((r (array-end a 0))
        (c (array-end a 1)))
    (dotimes (row (- r 1))
      (dotimes (col (- c 1))
        (display (array-ref a row col))
        (display #\space))
      (newline))))