INTERPRETER

Notes:

• Apparently let has the following syntax: (let (#definitionexprs) (returned expr)) Lets say we want to define $x = 5$, $y = 6$ in a local frame, and then return their sum. We can do: (let ((x 5) (y 6)) (+ x y))

Example: While statements

Sum of squares of even numbers less than 10, beginning with 2

(begin (define (f x total) 
  (if (< x 10)
  (f (+ x 2) (+ x total)) 
  total)
)
(f 2 0)
)

Sum of squares of numbers whose square is less than 50, beginning with 2

(begin 
(define (f x total)
  (if (< (* x x) 50) 
  (f (+ x 1) (+ total (* x x)))
  total
  )
)
 (f 2 0)
)

NEW TASK: WE WANNA CREATE A FUNCTION THAT RETURNS AN EXPRESSION THAT DOES THE ABOVE

(define (sum-while initial-x condition add-to-total update-x)
  `(begin (define (f x total)
  (if ,condition (f ,update-x (+ total ,add-to-total))
  total
  )
)

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