while (<HANDLE>) { ... } # same as ...
while (defined($_ = <HANDLE>)) { ... }

##</code><code>##

foreach (@list) { ... } # same as foreach $_ (@list) { ... }

##</code><code>##

$count = grep { BLOCK } LIST;
@result = grep { BLOCK } LIST;
@result = map { BLOCK } LIST;
map { BLOCK } LIST; # invalidates your warranty