2020-05-18-am.rkt

#lang racket

(module sim-AQSE3.5 racket

  (provide
   (rename-out [lambda lam])
   #%module-begin
   #%app
   #%datum
   + - * / >= <= > <
   if
   box
   unbox
   set-box!
   vars
   begin
   )

  (define-syntax-rule (vars ([x e] ...) eb)
    ((lambda (x ...) eb) e ...))
  )
  
;; put all of your code in the "foo" module, below.

;; 1) write a block of code that creates a box containing 22, updates the
;; box to be 44, and then returns the value in the box.

;; 2) write a function box-incr that accepts a box and an integer and updates
;; the box to contain the original value in the box plus the value of the
;; integer. What should it return? It doesn't matter. Return the number 17.

;; 3) using "vars" and the self-reference technique we described earlier,
;; define a "while" function that accepts itself and also a "guard" and
;; a "body" procedure. The while function should call the "guard" procedure,
;; and if it returns true, call the "body" procedure and then re-invoke the
;; "while" function. If the guard returns false, the "while" function exits
;; with the value 1235.

;; 4) use your "while" function to model this loop as it would be written in C:
#|
  int sum = 0;
  int n = 10;
  while (n > 0) {
    sum = sum + n;
    n = n - 1;
  }
|#

(module foo (submod ".." sim-AQSE3.5)

  {+ 33 44}
  
  )

(require 'foo)