An interesting demo

[Doug McIlroy]

For a demonstration of the power of m4 stripped to the
bare minimum--no builtins other than `define'--see
www.cs.dartmouth.edu/~doug/barem4.txt. (Because browsers
may not like .m4 files, it's called .txt--but is not
Windows format.) Well-commented code builds quickly from
nothing to binary arithmetic. Final remarks outline how
to simulate a computer and its memory--all within m4.

To try it, you might begin by entering one of the many
examples given in the program's comments:

prompt> m4 barem4.txt -
base2(mpy(add(one,two)),two))
110
add(one,two)
(1,(1,()))

I hope you enjoy it. Comments and criticism will be
gratefully received.

Doug