(load "record.ss")
(load "1.ss")

(define-record num (val))
(define-record varref (var))
(define-record lambda (formals body))
(define-record app (operator operands))

(define recordify
  (lambda (exp)
    (cond
      ((number? exp) (make-num exp))
      ((symbol? exp) (make-varref exp))
      ((atom? exp) (error 'recordify "illegal expression ~s" exp))
      ((eq? (car exp) 'lambda)
       (make-lambda (cadr exp) (recordify (caddr exp))))
      (else (make-app (recordify (car exp)) (map recordify (cdr exp)))))))

(define listify
  (lambda (exp)
    (variant-case exp
      (num (val) val)
      (varref (var) var)
      (lambda (formals body) (list 'lambda formals (listify body)))
      (app (operator operands)
	(cons (listify operator) (map listify operands)))
      (else (error 'listify "illegeal representation ~s" exp)))))

(define free-vars
  (lambda (exp)
    (variant-case exp
      (num (val) '())
      (varref (var) (list var))
      (lambda (formals body) (remove-all formals (free-vars body)))
      (app (operator operands)
	(append (free-vars operator) (append-all (map free-vars operands))))
      (else (error 'free-vars "illegeal representation ~s" exp)))))

(define convert
  (lambda (exp)
    (convert-h exp '())))

(define convert-h
  (lambda (exp env)
    (variant-case exp
      (num (val) val)
      (varref (var) (list ': (get-depth var env) (get-offset var env)))
      (lambda (formals body)
	`(lambda (,length formals) (convert-h body (cons formals env))))
      (app (operator operands)
	(cons (convert-h operator env)
	  (map (lambda (x) (convert-h x env)) operands)))
      (else (error 'convert "illegeal representation ~s" exp)))))

(define subst
  (lambda (v e b)
    (variant-case b
      (num (val) b)
      (varref (var) (if (eq? v var) e b))
      (lambda (formals body)
	(if (memq v formals) b (make-lambda formals (subst v e body))))
      (app (operator operands)
	(make-app (subst v e operator)
	  (map (lambda (x) (subst v e x)) operands)))
      (else (error 'convert "illegeal representation ~s" b)))))