Ah !!!
I had read about lazy and eager, but not appreciated what effect it
might have.
So the answer for my Tarjan module, which assumes a static network, is
to replace '.sort' with '.eager' .
However, ... the point at which I was getting an error in the modules
was the following code
Have you considered the effects of lazy evaluation for the hash's values
method? .sort will eagerly evaluate the whole .values list (i.e.
snapshot it) while iterating over it will include added keys and such.
This is to ask advice on how to pin down what appears to be a subtle bug
in Rakudo so that I can file a bug report.
*Background*
I am updating the work I have down on ModuleCitation, which is not
efficient at present.
Since I am create a recursive index, that is modules which cite modules,
