LISP Programming 1062_ex1

exercise 1: figure out the sum of squares of the minimum two arguments
Write a procedure named 'sum-of-square-min-two' which accepts three  
arguments and will figure out the sum of squares of the minimum two
arguments. 

$ scheme48
> ,load ex1-sum-square-min-two.scm
> 
> (sum-of-square-min-two 1 2 3)
5
> (sum-of-square-min-two 1 2 -3)
10
> (sum-of-square-min-two 2 2 2)
8
> ,exit
$

解答:
;figure out the sum of squares of the minimum two arguments 
(define (square x)
      (* x x))
(define (min-two-square a b c)
    (if (<= a b)
        (if (<= b c)
            (list (square a) (square b))
            (list (square a) (square c)))
        (if (<= a c )
            (list (square b) (square a))
            (list (square b) (square c)))))
(define (sum-data x y)
    (+ x y))
(define (sum-of-square-min-two a b c)
    (apply sum-data (min-two-square a b c)))

執行結果：