@{
    createList() {
      return {};
    }

    append(s, e) {
      s[length(s)] = e;
    }

    map(f, seq, g) {
      out = {};
      if (g) {
        for (i in seq) {
          e = seq[i];
          if (g(e)) { e = f(e); }
          append(out, e);
        }
      } else {
        for (i in seq) {
          append(out, f(seq[i]));
        }
      }
      out;
    }

    select(f, s) {
      out = {};
      for (i in s) {
        e = s[i];
        if (f(e)) { append(out, e); }
      }
      out;
    }

    reject(f, s) {
      out = {};
      for (i in s) {
        e = s[i];
        if (!f(e)) { append(out, e); }
      }
      out;
    }
    
    last(s) {
      s[length(s)-1];
    }
}