"mid" is too specific. A "mean" function may be good as part of a statistics package. Doesn't seem like a good addition to the core.
How about resorting to algebra and using the commutation my $middle = floor($l / 2 + $r / 2); or, if you want to use bit ops and integer math, "$l +> 1 + $r +> 1 + ($l mod 2 + $r mod 2) +> 1" Though I'm still not convinced that the potential performance hit of upgrading numbers to avoid an overflow on adding large indexes is worth the extra operations in the general case. -y
