my %op_table = (
    le => sub { $_[0] <= $_[1] },
    ge => sub { $_[0] >= $_[1] },

    # etc.
    );

exists $op_table{ $op } or die "The operator '$op' does not exist.\n";

if ( $op_table{ $op }->( $a, $b ) ) {
    do something
    }
else {
    do something else
    }