@to_be_sorted=qw( cat bird dog tiger puma mouse );
@order=qw( mouse cat dog lion elephant );

%order=();
for($_=0; $_<@order; $_++) { $order{$order[$_]}=$_; }

@sorted=sort {
        $order{$a}=@order unless exists $order{$a};
        $order{$b}=@order unless exists $order{$b};
        $order{$a}<=>$order{$b}
         } @to_be_sorted;