[plt-scheme] efficient string operations yielding immutablestrings

By the way, my use of immutable strings is mainly only to catch library
use errors.  The library API is being designed so that a much less
efficient R5RS reference implementation suitable for SRFI could later be
written.

The SRFI would probably have to specify that "behavior is undefined" if
a program attempts to mutate certain objects.  The PLT implementation of
the SRFI (by virtue of its use of immutable versions of strings,
structs, vectors, pairs) actually signals an error on an erroneous
attempt at mutating.

I'm pretty pleased that this seems to be working out in PLT Scheme.  
Otherwise I'd have to learn Ocaml (and a little French) right now.

-- 
                                             http://www.neilvandyke.org/