Lexical and Dynamic Scoping - Answers to Mini-Exercises

1. What does this print? What would it print if Racket used dynamic scoping?

   (define y 0)
   (define (y-printer) (display y))
   
   (let ((y 10))
     (y-printer))
   
   
   Racket: 0
   Racket with dynamic scoping: 10
   

2. What is the value of the let? What would it be if Racket used dynamic scoping?

   (define y 0)
   
   (let ((y 10)
         (f (lambda (x) (+ x y))))
     (f 1))
   
   
   Racket: 1
   Racket with dynamic scoping: 11  (since we'd find the y=10 binding instead
   of the global one)
   

3. Consider the following Racket code.

   (define n 0)
   
   (define (get-n) n)
   
   (define (squid) (get-n))
   
   (define (octopus n) (squid))
   

   what does (squid) evaluate to? What does (octopus 8) evaluate to? What would be the result in a dynamically scoped version of Racket?

   Racket: (squid) evaluates to 0; (octopus 8) also evaluates to 0 
   
   
   Racket with dynamic scoping:
   (squid) evaluates to 0; (octopus 8) evaluates to 8