The version you have put in Rosettacode is good, I have just
added some missing tests at the beginning of the UTM constructor.
Annotations like this are reminders of DMD bugs/limits that
hopefully we'll be fixed/lifeted:
foreach (/*const*/ s, const rule; aa) {
While this annotation:
alias State = char; // Typedef?
means that in a stronger typed entry maybe State should be (but
we have also to benchmark if this doesn't decrease the program
performance for a successive bigger Busy Beaver machine):
alias State = Typedef!char;
This little program is pedagogically very good at showing the
difference between weak and strong static typing. In a strongly
static typed version all (or most) of those run-time tests are
not needed.
Bye,
bearophile
