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#lang racket/base
(require web-server/http
net/url)
(define interface-version 'stateless)
(provide start interface-version)
(define (start req)
(let* ([uri (request-uri req)]
[qry (url-query uri)])
(cond
[(assoc 'second qry)
=> (lambda (a-pair)
(response/xexpr
`(html (head (title "Answer Page"))
(body
(h1 "Answer Page")
(p ,(format "The answer is: ~a"
(+ (string->number (cdr a-pair))
(string->number (cdr (assoc 'first qry))))))))))]
[(assoc 'first qry)
=> (lambda (a-pair)
(response/xexpr
`(html (head (title "Second Page"))
(body
(h1 "Second Page")
(form ([action ,(url->string uri)]
[method "get"] [enctype "application/x-www-form-urlencoded"])
"Enter the second number to add: "
(input ([type "hidden"] [name "first"] [value ,(cdr a-pair)]))
(input ([type "text"] [name "second"] [value ""]))
(input ([type "submit"] [name "enter"] [value "Enter"])))))))]
[else
(response/xexpr
`(html (head (title "Hello"))
(body
(h1 "Hello World!")
(form ([action ,(url->string uri)]
[method "get"] [enctype "application/x-www-form-urlencoded"])
"Enter the first number to add: "
(input ([type "text"] [name "first"] [value ""]))
(input ([type "submit"] [name "enter"] [value "Enter"]))))))])))
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