Character encoding / poor man's letterspacing

[Urs Liska]

Hi,

I've written a poor-man's implementation of a simple \letterspaced markup command:

#(define-markup-command
  (letterspaced layout props text)(markup?)
  (let*
   ((chars (string->list text))
    (dummy (ly:message "Chars: ~a" chars))
    (spaced-text
     (string-join
      (map string chars) " ")))
   (interpret-markup layout props
     (markup spaced-text))))

However, this scrambles umlauts and presumably other UTF-8 characters as you can see with

{
  s1 ^\markup \letterspaced "Täst"
}

=> Chars: (T � � s t)

Obviously the characters are wrongly en/decoded along the way, which makes me think whether I have simply forgotten an encoding setting somewhere (although I have no idea where and how I should include that) or whether that whole routine is totally clumsy.

Any pointer would be appreciated.

Best Urs