haunt-sass-hack.scm

(make-page "foo.css"
           ;; Add other necessary context here.
           '((input-file . "foo.scss"))
           (lambda (args port)
             ;; I don't use a sass compiler so I'm just making the
             ;; options up.  Hopefully sass can output to STDOUT.
             (let* ((pipe (open-pipe* OPEN_READ "sass" (assq-ref args 'input-file))))
               ;; There's ways of doing i/o redirection so you don't
               ;; have to read the entire pipe output into Scheme, but
               ;; I don't remember how off the top of my head and this
               ;; is just a quick example rather than an efficient
               ;; one.
               (display (get-string-all pipe) port)
               (unless (zero? (status:exit-val (close-pipe pipe)))
                 (error "uh oh")))))