Problem 21

Recall that the composition of two functionsf and g-- is h(x) = f(g(x)). Of course, the range of g must be a subset of the domain of f. Implement a generic compose combinator.

Problem 22

Use recursion and your solution to problem 1 to implement the self-composition iterator combinator:

def selfIter[T](f: T=>T, n: Int) = f composed with itself n times.

Test your function with:

def inc(x: Double) = x + 1

def double(x: Double) = 2 * x

Note:

selfIter(f, 0)= id where id(x) = x.