Shift and Unshift on Inf lists

[Stevan Little]

Okay, more edge cases here.
Both these examples:
pugs -e 'my @a = (1 .. Inf); shift(@a);'
pugs -e 'my @a = (1 .. Inf); unshift(@a, 10);'
take forever (or rather, however long Inf is, but that is a discussion 
for another list).

I think this might be the wrong behavior. I would expect that for pop() 
or push() which need to find the end of the list, and therefore take a 
*very* long time. But why do shift() and unshift() need to find the end 
of the list?

I freely admit that I may be completely naive on this subject, so 
please correct me if I am wrong.

Thanks,
Stevan