Hailperin, Chapter 5

Slides, Higher-Order Procudures, functions as parameters

Slide of ch5a.rkt
=================
(define power
  (lambda (b e)
    (if (= e 1)
        b
        (* (power b (- e 1)) b))))

(define stack-copies-of
  (lambda (quantity image)
    (if (= quantity 1)
        image
        (stack (stack-copies-of (- quantity 1) image) image))))

Load ch5a.rkt and demo:

> (power 2 1)
> (power 2 2)
> (power 2 3)
> (stack-copies-of 1 rcross-bb)
> (stack-copies-of 2 rcross-bb)
> (stack-copies-of 3 rcross-bb)

Slides, How are the functions similar?

Slides, How are the functions different?

Slides, together-copies-of, ..., define power

Load ch5b.rkt and repeat demo:

> (power 2 2)
> (stack-copies-of 2 rcross-bb)

Slide of ch5c.rkt
=================
(define num-digits-in-satisfying
  (lambda (n test?)
    (cond ((< n 0)
           (num-digits-in-satisfying (- n) test?))
          ((< n 10)
           (if (test? n) 1 0))
          ((test? (remainder n 10)) 
           (+ (num-digits-in-satisfying (quotient n 10) test?)
              1))
          (else 
           (num-digits-in-satisfying (quotient n 10) test?)))))

Slide, What is the definition of num-odd-digits?

Slide, What is the definition of num-6s?

Load ch5c.rkt and demo

Slides, The Halting Problem

After the proof, load ch5d.rkt and show that it compiles.

Slides, Procedure factories, Define make-multiplier

Load ch5e.rkt (do not show make-repeated-version-of) and demo

> (double 7)
> (triple 12)

Slides, Manufacture a function that calls itself

After last slide demo

(repeatedly-square 2 2)
(repeatedly-square 2 3)