Welcome to the CHICKEN Scheme pasting service

;;; first idea
;; this is pretty verbose, redundant and error-prone

(vhost-map `(((* any) . ,
              (with-headers-dump
               (with-session
                (lambda (continue)
                  ...))))))


(define (with-headers-dump handler)
  (lambda (continue . args)
    (pp (headers->list (request-headers (current-request))))
    (apply handler continue args)))

(define (with-session handler)
  (lambda (continue . args)
    (parameterize ((current-session ...))
      (apply handler continue args))))


;;; second idea
;; this is similar to how spiffy handlers themselves work and is less
;; redundant but requires a helper procedure `wrap-handler'

(vhost-map `(((* any) . ,
              (wrap-handler 
               with-headers-dump
               with-session
               (lambda (continue)
                 ...)))))

(define (wrap-handler . wrappers)
  (let* ((wrappers (reverse wrappers))
         (handler (car wrappers))
         (wrappers (cdr wrappers)))
    (fold (lambda (wrapper handler)
            (lambda args
              (wrapper (lambda ()
                         (apply handler args)))))
          handler
          wrappers)))


(define (with-headers-dump continue)
  (pp (headers->list (request-headers (current-request))))
  (continue))

(define (with-session continue)
  (parameterize ((current-session ...))
    (continue)))