$ perl -wMstrict -Mdiagnostics -le 'my @array; print defined(@array)'
Can't use 'defined(@array)' (Maybe you should just omit the defined()?) at -e
	line 1 (#1)
    (F) defined() is not useful on arrays because it
    checks for an undefined scalar value.  If you want to see if the
    array is empty, just use if (@array) { # not empty } for example.
    
Uncaught exception from user code:
	Can't use 'defined(@array)' (Maybe you should just omit the defined()?) at -e line 1.

$ perl -wMstrict -le 'my @array=(undef); print @array?"true":"false"'
true