% say "@x= @x || 2..4"
2
3
4
 % say "@x ||= 2..4"
Can't modify array dereference in logical or assignment (||=)...

 % say
{ my $x; sub f:lvalue { $x += shift @_; return $x } }
f(2) ||= 3, f(10)
__END__
2
12
 % say
{ my $x; sub f:lvalue { $x += shift @_; return $x } }
f(2)= f(2) || 3, f(10)
__END__
2
14