;;  ------------------------------------------------------------------------
;; |   FILE           :  homework07.rkt                                     |
;; |   AUTHOR         :  [ YOUR NAME ]                                      |
;; |   CREATION DATE  :  [ YOUR DATE ]                                      |
;; |   DESCRIPTION    :  [ YOUR COMMENT ]                                   |
;;  ------------------------------------------------------------------------

#lang racket
(require "syntax-procs.rkt")
(provide curry
         empty-set   set-member?   set-add
         set-union
         set-subset?
         free-vars
         preprocess)               ; I provide this from class, for testing

;; --------------------------------------------------------------------------
;; Problem 1                                           (structural recursion)
;; --------------------------------------------------------------------------

(define curry
  (lambda (lambda-exp)
    'fill-in-the-blank))

;; --------------------------------------------------------------------------
;; Problem 2                                        (non-recursive solutions)
;; --------------------------------------------------------------------------

(define empty-set
  (lambda ()
    'fill-in-the-blank))

(define set-member?
  (lambda (sym S)
    'fill-in-the-blank))

(define set-add
  (lambda (sym S)
    'fill-in-the-blank))

;; --------------------------------------------------------------------------
;; Problem 3                                           (structural recursion)
;; --------------------------------------------------------------------------

(define set-union
  (lambda (S1 S2)
    'fill-in-the-blank))

;; --------------------------------------------------------------------------
;; Problem 4                                           (structural recursion)
;; --------------------------------------------------------------------------

(define set-subset?
  (lambda (S1 S2)
    'fill-in-the-blank))

;; --------------------------------------------------------------------------
;; Problem 5                                           (structural recursion)
;; --------------------------------------------------------------------------

(define free-vars
  (lambda (exp)
    'fill-in-the-blank))

;; --------------------------------------------------------------------------
;; preprocess :: full-exp -> core-exp          (for use in testing Problem 5)
;; --------------------------------------------------------------------------

(define preprocess
  (lambda (exp)
    (cond
      ( (varref? exp) (make-varref exp) )
      ( (lambda? exp)
           (make-lambda (lambda->param exp)
                        (preprocess (lambda->body exp))) )
      ( (app? exp)
           (make-app (preprocess (app->proc exp))
                     (preprocess (app->arg  exp))) )
      ( else  ;; let
           (let ((var  (let->var  exp))
                 (val  (let->val  exp))
                 (body (let->body exp)))
             (make-app (make-lambda var (preprocess body))
                       (preprocess val)) ) ))))

;; --------------------------------------------------------------------------