previous | index | next

Function Composition

Recall: If g is a function whose values are acceptable as arguments to f, then the composition of f and g is: 
     f(g(x))
Exercise 5.16: Write a procedure that takes two procedures as arguments and returns the procedure that is their composition as a result. 
     (define compose	
       (lambda (f g)	
         (lambda (x) (f (g x)))))
Q: How to define sqrt_abs (using compose) so that 
     (sqrt_abs -16) ⇒ 4 ?
A: 
     (define sqrt_abs (compose sqrt abs))
previous | index | next