On Tue, Jun 30, 2020 at 4:35 PM Marc Nieper-Wißkirchen
<xxxxxx@nieper-wisskirchen.de> wrote:
> Finally, the way it is spec'ed in SRFI 130 doesn't allow an
> implementation of string cursors by integers that are not necessarily
> indices (a cursor could be a byte offset).

You could do it, you just need to box the index in a separate type.
This is how it's done in Gauche, which stores byte offset most of the
time (but with a separate tag, so it's distinct from integers)
--
Duy