On Wed, 18 May 2005, Rob Kinyon wrote:
1) undef (which may or may not contain an exception), or 2) some unit/identity value that is a trait of the operator,
depending on whether or not people think (2) is actually a good idea.
I would think that the Principle of Least Surprise points to (1),
I don't think so. I, for one, would expect [+]; to return zero and [*]; to return 1. But that's only because I {trust,expect} perl(6) to be smart enough to DWIM.
Michele -- \renewcommand\labelitemi{\textcolor{yellow}{\textbullet}} would change the colour of the first-level bullet, and improve the document so's i can't see the bullets. - Robin Fairbairns in comp.text.tex
