http://www.perlmonks.org?node_id=997560


in reply to Re^5: Order in which grep/map receive elements
in thread Order in which grep/map receive elements

uniq:
+ self describing code
+ behavior is guaranteed by module docs
- needs a module (but I have it on our servers already)

grep:
- unobvious construct
- behavior might change in future versions of perl (although that's unlikely)
- declares auxiliary variable that might interfere with other code

The choice is quite obvious to me. :-)