; binding of variables in lambda expressions

; what is the result of evaluating (foo 2) in each case

; Case 1
(define y 1)
(define foo (lambda (x) (+ x y)))
(foo 2)

; Case 2
(define y 2)
(foo 2)

; Case 3
(define y 3)
(foo 2)

; Case 4
(let ((y 4)) (foo 2))

; Case 5
(define foo 
  (let ((y 4))
    (lambda (x) (+ x y))))

(foo 2)