Redirect Support

Perhaps we would want to control redirects from within the scripts - ideally something like below should work:

(redirect! url) 

To enable such handling is straight forward:

(define (redirect! url 
                   #:status (status 'temporary-redirect) 
                   #:headers (headers '()))
  (define (header-helper h)
    (cond ((header? h) h)
          ((pair? h) (make-header (string->bytes/utf-8 (car h))
                                  (string->bytes/utf-8 (cdr h))))
          ((cookie? h)
           (cookie->header h))))
  (redirect-to (if (url? url) (url->string url) url)
               (case status
                 ((found) permanently)
                 ((see-other) see-other)
                 ((temporary-redirect) temporarily))
               #:headers (map header-helper headers)))

The wrapper over redirect-to simplifies type conversion between url and string, and pairs of string to header, as well as cookie to header, so you can do the following:

(redirect! '/another/path' #:headers `(("test" . "me") ,(cookie-ref! "session")))

As redirect-to only returns a response/full struct, we need to raise the struct so we can escape the calling stack if the script is being included. And let's catch the object at the request handling:

(define (handle-request server request)
  (parameterize (($pathinfo ($pathinfo))
                 ($server server)
                 ($request request))
    (parameterize (($cookies (init-cookies!)))
      (eval-script-if-changed! (shp-handler-required server))
      (with-handlers ((response/basic? 
                       (lambda (r) r)))
        (make-response (include! (request-uri request) 
                                 #:topfilter (shp-handler-topfilter server)
                                 #:partial? #t))))))

Now we can do a redirect from within the scripts! ;)