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Exercise 2.20
Generalized compose ***


We have seen the compose function on a previous slide.

Let us here work with a variant of compose called self-compose:

 (define (self-compose-2 f)
   (lambda (x)
     (f (f x))))

You first job is to generalize self-compose-2 to self-compose*, which composes the f with itself n times:

 (define (self-compose* f n)
   ...)

Test your function appropriately.

Also, program a function compose* which takes a list of functions as arguments. Each function in the list must be of a single parameter. Your function must return the composition of all the functions. Here is an example of the intended use of the function:

 > ((compose* (list incr - fac)) 5)
 -119

fac is here supposed to be the factorial function, and incr is the usual increment function. The expression (compose* (list incr - fac)) should be equivalent to (lambda (x) (incr (- (fac x)))).

Are you able to program compose* with a reduction function and compose?


Solution