Beginners problem with display in an include file

[Peter Gentry]

\version "2.18.2"
;;; OS Vista and Frescobaldi
;;; attempt to improve include file enharmonic.ly
;;; why does guile display fail to produce an output to thefresobaldi log file
#(ly:message "Test debug 1\n")
#(define (naturalize-pitch p)
(let ((o (ly:pitch-octave p))
(a (* 4 (ly:pitch-alteration p)))
;;; alteration, a, in quarter tone steps,
;; for historical reasons
(n (ly:pitch-notename p)))
(cond
((and (> a 1) (or (eq? n 6) (eq? n 2)))
(set! a (- a 2))
(set! n (+ n 1)))
((and (< a -1) (or (eq? n 0) (eq? n 3)))
(set! a (+ a 2))
(set! n (- n 1))))
(display a)
(cond
 ((> a 2) (ly:message "a>2"))
 ((< a -2) (ly:message "a<-2"))
)
(cond
((> a 2) (set! a (- a 4)) (set! n (+ n 1)))
((< a -2) (set! a (+ a 4)) (set! n (- n 1))))
(cond
 ((< n 0) (ly:message "n<0"))
 ((= n 0) (ly:message "n=0"))
 ((= n 1) (ly:message "n=1"))
 ((= n 2) (ly:message "n=2"))
 ((= n 3) (ly:message "n=3"))
 ((= n 4) (ly:message "n=4"))
 ((= n 5) (ly:message "n=5"))
 ((= n 6) (ly:message "n=6"))
 ((> n 6) (ly:message "n>6"))
)
(if (< n 0) (begin (set! o (- o 1)) (set! n (+ n 7))))
(if (> n 6) (begin (set! o (+ o 1)) (set! n (- n 7))))
(ly:make-pitch o n (/ a 4))))
#(ly:message "Test debug 3\n")
#(define (naturalize music)
(let ((es (ly:music-property music 'elements))
(e (ly:music-property music 'element))
(p (ly:music-property music 'pitch)))
(if (pair? es)
(ly:music-set-property!
music 'elements
(map (lambda (x) (naturalize x)) es)))
(if (ly:music? e)
(ly:music-set-property!
music 'element
(naturalize e)))
(if (ly:pitch? p)
(begin
(set! p (naturalize-pitch p))
(ly:music-set-property! music 'pitch p)))
music))
naturalizeMusic =
#(define-music-function (parser location m)
(ly:music?)
(ly:message "Test debug 4\n")
(naturalize m))

I an trying to get some debug feedback from the code but ly:message only seems 
to allow strings and display reutns nothing. I'll bet
it's a simple missunderstanding of the guile scheme interface.

regards
Peter Gentry