1 ;; The first three lines of this file were inserted by DrScheme. They record metadata
2 ;; about the language level of this file in a form that our tools can easily process.
3 #reader(lib "htdp-intermediate-reader.ss" "lang")((modname 18.1.14) (read-case-sensitive #t) (teachpacks ((lib "draw.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "draw.ss" "teachpack" "htdp")))))
4 ;A web-page (wp) is a structure:
5 ;(make-wp header doc) where
6 ;header is a symbol and doc is
7 ;a web-document.
8 ;
9 ;A web-document (doc) is either
10 ;1. empty,
11 ;2. (cons sym doc) where sym is a symbol and
12 ;doc is a web-document, or
13 ;3. (cons wp doc) where wp is a webpage and
14 ;doc is a web-document.
15 
16 (define-struct wp (header doc))
17 
18 ;find : wp symbol -> list-of-symbols/false
19 ;Given a-wp and a-symbol, return the headers
20 ;of the web-pages that are accessed on the way
21 ;to locating a-symbol.  Returns false
22 ;if a-symbol never occurs.
23 
24 (define (find a-wp a-symbol)
25   (cond
26     []
27     []
28     []))