void
read_csv(list t, text path)
{
    file f;
    list l;

    f_affix(f, path);
    while (f_news(f, l, 0, 0, ",") ^ -1) {
        l_append(t, l);
    }
}

list
sum_columns(list t)
{
    list c, l;
    integer i;

    l_append(c, "SUM");
    for (i, l in t) {
        if (i) {
            integer j, sum;
            text s;

            sum = 0;
            for (j, s in l) {
                sum += atoi(s);
            }

            l_append(c, sum);
        }
    }

    return c;
}

void
add_column(list t, list c)
{
    integer i;
    list l;

    for (i, l in t) {
        l_append(l, c[i]);
    }
}

void
write_csv(list t, text path)
{
    integer i;
    file f;
    list l;

    f_create(f, path, 00644);
    for (i, l in t) {
        f_(f, l[0]);
        l_ocall(l, f_, 2, 1, -1, f, ",");
        f_newline(f);
    }
}

integer
main(void)
{
    list t;

    read_csv(t, "tmp/CSV_data_manipulation.csv");
    add_column(t, sum_columns(t));
    write_csv(t, "tmp/CSV_data_manipulated.csv");

    return 0;
}