$ echo 'Applying pattern match to @array will act on scalar(@array) at e.pl lin
e 29'|splain|fmt
Applying pattern match to @array will act on scalar(@array) at e.pl line
29 (#1)
    (W misc) The pattern match (//), substitution (s///),
    and transliteration (tr///) operators work on scalar values.
    If you apply one of them to an array or a hash, it will convert the
    array or hash to a scalar value -- the length of an array, or the
    population info of a hash -- and then work on that scalar value.
    This is probably not what you meant to do.  See perlfunc/grep and
    perlfunc/map for alternatives.