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
这个练习是使用高阶函数的另外一个例子。
(define (compose f g)
(lambda (t)
(f (g t))))
;;; tests begin
(load "../testframe.scm")
(assert= ((compose square (lambda (x) (+ x 1))) 6) 49)