;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-intermediate-lambda-reader.ss" "lang")((modname lets) (read-case-sensitive #t) (teachpacks ((lib "docs.rkt" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "docs.rkt" "teachpack" "htdp")) #f)))
(let ((x 2))  (* x x))   ; should return 4
(let ((x 2)) (let ((y 1)) (+ x y))) ; should return 3

(let* ((x 10) (y (* 2 x))) (* x y)) ; yields 200

;(let ((x 10) (y (* 2 x))) (* x y))
;  (let ((x 10) (y (* 2 x))) (* x y)) is in error as can't have dependences 
;  between binding list elements because that implies an order of execution
;  message sent is this  x: this variable is not defined

(let ((x 10))
  (let ((f (lambda (a) (+ a x))))
    (let ((x 2)) (f 5)))) ; returns 15 which s (+ 5 10) NOT (+ 5 2)
                          ; good example of lexical scoping; inner varible x
                          ; hides the outer scope x

(define (f z)
  (let* ((x 5) (f (lambda (z) (* x z))))
    (map f z)))
(f '(1 2 3))