Higher Order Procedures:

1. Define a procedure (pa f x) which "partially applies" a 2 argument
procedure f to its first argument x.  Example:
  (define inc (pa + 1))
  (inc 3) => 4

(define (pa f x)





2. Currying lets us pass a procedure its arguments one at a time.
From the problem set, curry is defined as
  (define (curry f)
    (lambda (x)
      (lambda (y)
	(f x y))))

Write a procedure (uncurry cf) which takes a curried procedure and
returns a procedure of two arguments (so (uncurry (curry +)) is +)

(define (uncurry cf)





3. What does the procedure returned by (pa pa pa) do?



4. What does the procedure returned by (uncurry curry) do?



List Practice:

1. Use map to double every element of a list l.



2. Use filter to remove from a list l any numbers that are not squares
of integers.



3. Use accumulate to count the number of even numbers in a list l.