(define (loader-printer s)
  (print "Hello, " s))

(define-syntax include-with-prelude
  (syntax-rules ()
    ((include-with-prelude path)
     (lambda (#!key printer)
       (include-relative path)))))

;(define loaded (include-with-prelude "loaded.scm")) ; doesn't work
(define loaded (lambda (#!key printer) (include-relative "loaded.scm")))

(loaded printer: loader-printer)