https://github.com/gambiteer/srfi-231/commit/24b24f83ef3d5074a71bbf51f19402096f9488df

This commit adds array-stack!, array-decurry!, array-append!,
array-block!, which are not call/cc safe, but which may be faster and
use less space than the call/cc-safe versions.

Once the original routines were call/cc safe, the substantive change to
make each of the new routines was one line of code.

With an explanation near the top of the SRFI documentation about what
the ! means in procedure names, I believe that each of these new
routines will also require only one line of documentation, the procedure
declaration.

More changes soon.

Comments welcome.

Brad