Downcase of a symbol

[Urs Liska]

Hi,

I have written a function to return the lowercase version of a symbol
for use in my library as

% Return the lowercase version of a symbol
#(define (symbol->lowercase sym)
   (string->symbol
    (string-downcase
     (symbol->string sym))))

Just a small question: this seems so general that I can't imagine it
isn't already available somewhere in Scheme, Guile or LilyPond. Of
course I'd prefer using an official function instead of my own.

Thanks for any pointers
Urs