SICP - Solution: Exercise 1.42

# SICP - Solution: Exercise 1.42

##### October 29, 2018

Exercise 1.42: Let $f$ and $g$ be two one-argument functions. The composition $f$ after $g$ is defined to be the function ${x\mapsto f(g(x))}$. 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


Solution

From the definition, we can write:

(define (compose f g)
(lambda (x)
(f (g x))))