> Currently, with-let is immutable -- I don't think that's
> the perfect solution, but it's simpler than using
> #_with-let all the time.  A lot of that portion of
> s7 is experimental.

If we manage to arrive at a SRFI 177 design that Scheme implementors are
generally satisfied with, would you be willing to ship the macros with
s7? That way the SRFI implementation can evolve with s7's macro system.

The current s7 implementation is a 27 lines, 5 lines of which is a
`split-last` helper. So it's not huge but it'd be nice to find something
even simpler.