Richard Kelsey <xxxxxx@s48.org> writes:
>    If I'm using some exotic string representations (I'm working on a
>    functional-splay-tree string type for Pika) -- same deal:
>    extract-string may take some (possibly GC-causing) work.
>
> This does worry me (it's listed in the 'issues' section of the SRFI).
> I think we went overboard here.  Something like
>
>     SCHEME_EXTRACT_STRING_CONTENTS(scheme_value, index, count, buffer)
>
> which copies 'count' characters starting from 'index' into 'buffer'
> would be better.  Presumably this can be done without GCing.

For what it's worth:

The Xerox PARC Portable Common Runtime had "ropes", which were a
tree-based string representation that could include portions whose
contents were computed lazily, by calling a function when they were
referenced.