here is the source for a working plan 9 version:
http://www.9front.org/extra/crabs.tgz

fun to watch.

On Sat, Feb 22, 2020, 1:02 AM Dave Horsfall <dave@horsfall.org> wrote:

> On Sat, 22 Feb 2020, Warren Toomey wrote:
>
> > http://lucacardelli.name/Papers/Crabs.pdf
>
> Sheer genius in its simplicity of implementation!  For some reason I am
> reminded of "xroach": I used to surprise my cow-orkers with it...
>
> -- Dave
>