SICP Ex 1.3 错误；句法关键字不能用作表达式：#[keyword-value-item 13]

Question

嘿，我正在尝试编写一些方案，你能帮我吗？

(define (square a b) (+ (* a a) (* b b)))

(define (sumsq x y z)
    (cond (and (< x y) (< x z) (square y z))
          (and (< y x) (< y z) (square x z))
          (else (square y z))))

(sumsq 1 2 3)

它给我一个错误;Syntactic keyword may not be used as an expression: #[keyword-value-item 13]

Answer 1

少了几个括号。这是 cond:

的正确语法

(define (sumsq x y z)
    (cond ((and (< x y) (< x z)) (square y z))
          ((and (< y x) (< y z)) (square x z))
          (else (square y z))))

SICP Ex 1.3 错误；句法关键字不能用作表达式：#[keyword-value-item 13]

SICP Ex 1.3 error ;Syntactic keyword may not be used as an expression: #[keyword-value-item 13]

scheme

functional-programming

sicp