Help! \mark, and lesson in Scheme

[Anthony W. Youngman]

I'm trying to "fix" \mark, so it works for me. Unfortunately, not 
knowing my way round Scheme, I've fixed it but in a way that might 
crash, and which will be wiped out by an upgrade.

Basically, I've increased the vector size (I guess that's what I'd call 
an array?). It seems to be necessary, but I don't understand why. Do 
vectors start at 0? I've also tried to increase the check on i, but I've 
realised that's probably a mistake! But *might* that cause a crash when 
we get to Z?

And I've commented out the line that increments i if it's the equivalent 
of "I" or bigger. The result is I'm now getting the letter I as a 
rehearsal mark.

============== (original from 2.4.2 define-markup-commands ll 629-

;(define number->mark-letter-vector (make-vector 25 #\A))
(define number->mark-letter-vector (make-vector 26 #\A))

(do ((i 0 (1+ i))
     (j 0 (1+ j)))
; swapping these two gets it to work ...
    ((>= i 26))
;    ((>= i 27))
;  (if (= i (- (char->integer #\I) (char->integer #\A)))
;      (set! i (1+ i)))
  (vector-set! number->mark-letter-vector j
               (integer->char (+ i (char->integer #\A)))))

==============

All I now need do is make it permanent. I want to create a 
"format-mark-alphabet" markFormatter. It seems so obvious - look in 
translation-functions.scm, and go from there. Except it seems I need to 
modify a copy of make-markletter-markup, and I can't find it to modify! 
(And I want to create a "format-mark-barnumber" markFormatter too.)

Both these formatters are needed for Band (both Brass and Wind) music. 
Since I noticed (and moaned about) format-mark-letter omitting the 
letter I a few months ago, I've been looking for examples. And I have 
yet to find ONE. Of the thirty or so pieces I've played since then, if 
they had an H, it was followed either by an I or the end of the piece. 
And while I haven't looked especially, I think the use of bar numbers 
outnumbers the use of numbers as a rehearsal mark. So that's why the 
other one's necessary.

Cheers,
Wol
--
Anthony W. Youngman - wol at thewolery dot demon dot co dot uk
HEX wondered how much he should tell the Wizards. He felt it would not be a
good idea to burden them with too much input. Hex always thought of his reports
as Lies-to-People.
The Science of Discworld : (c) Terry Pratchett 1999