sicp每日一题[1.42]

Exercise 1.42

Let $f$ and $g$ be two one-argument functions. The $composition$ $f$ after $g$ is defined to be the function $x->f(g(x))$. Define a procedure compose that implements composition. For example, if $inc$ is a procedure that adds 1 to its argument,

 ((compose square inc) 6)49

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这道题也非常简单，跟上一题几乎一模一样，只是把 double 换成一个通用的单参数函数而已。

(define (compose f g)(lambda (x) (f (g x))))((compose square inc) 6)
((compose inc square) 6); 执行结果
49
37