#lang plai
(require "wae.rkt")
(define named-expr (add (num 3) (id 'x)))

(test named-expr (parse '{+ 3 x}))

(define with-ex1 (with 'y named-expr (sub (id 'y) (num 7))))

(test with-ex1 (parse 
                '{with {y {+ 3 x}} 
                       {- y 7}}))

(test (subst with-ex1 'x 3) 
      (parse 
       '{with {y {+ 3 3}} 
              {- y 7}}))

(define with-ex2 (with 'y named-expr (sub (id 'y) (id 'x))))

(test with-ex2 (parse 
                '{with {y {+ 3 x}} 
                       {- y x}}))

(test (subst with-ex2 'x 3) 
      (parse 
       '{with {y {+ 3 3}} 
              {- y 3}}))

(define sub-ex (add (num 3) (num 3)))
(test (subst with-ex2 'y 3) with-ex2)
(test (subst with-ex2 'y sub-ex) with-ex2)

;;