Here is a solution to the exercise in which
we extend the RPAL version of Tiny's denotational
semantics description, to a larger language we'll
call Medium.

The RPAL code is in 'medium'.

'doall' is a shell script that runs the medium
interpreter ('mi') on each of 24 test programs.

'mi' is a 'medium interpreter', that
concatenates 'medium' with the given test program,
runs 'rpal' on the resulting temporary file,
and then removes the temporary file.

To run all 24 test programs, simply run 'doall'.
This shell script expects to find 'rpal' in your
current search path.

The expected results are in the 'results' file.

Enjoy.

