;; This buffer is for notes you don't want to save, and for Lisp evaluation.
;; If you want to create a file, visit that file with C-x C-f,
;; then enter the text in that file's own buffer.

(define-syntax my-let 
  (syntax-rules ()
    [(_ ((x v) ...) e1 e2 ...)
     ((lambda (x ...) e1 e2 ...)
      v ...)]))

(define-syntax my-if
  (syntax-rules (then else)
    [(_ e1 then e2)
     (if e1 e2)]
    [(_ e1 then e2 else e3)
     (if e1 e2 e3)]))

(define-syntax ++
    (syntax-rules ()
      [(_ x)
       (begin 
	 (set! x (+ x 1))
	 x)]))

(define-syntax ++-post
  (syntax-rules ()
    [(_ x)
     (let ([original-value x])
       (set! x (+ 1 x))
       original-value)]))

(define-syntax my-and
  (syntax-rules ()
    [(_) #t]
    [(_ exp) exp]
    [(_ exp1 exp2 ...)
     (if (not exp1)
	 #f
	 (my-and exp2 ...))]))

(define-syntax for
  (syntax-rules (:)
    [(_ (init : test : update ...) body ...)
     (begin
       init
       (let loop ()
	 (if test
	     (begin
	       body ...
	       update ...
	       (loop)))))]))
     

(for ((begin (define i 0)(define j 1)) : (< i 12) : (++ i))
     (display i)
     (display " ")
     (display j)
     (newline)
     (set! j (* 2 j)))