sclass SortedListBasedMap<A, B> extends CompactAbstractMap<A, B> {
  O[] entries; // key, value, ... with keys being sorted
  
  *() {}
  *(Map<A, B> map) {
    LPair<A, B> l = pairsSortedByA(mapToPairs(map));
    int n = l(l);
    entries = new O[n*2];
    for i to n: {
      entries[i*2] = l[i].a;
      entries[i*2+1] = l[i].b;
    }
  }
  
  public int size() { ret l(entries)/2; }
  public Set<Map.Entry<A, B>> entrySet() {
    ret toLinkedHashMap().entrySet();
  }
  
  int find(O o) {
    generalizedBinarySearch(entries)
    if (entries != null)
      for (int i = 0; i < entries.length; i += 2)
        if (eq(entries[i], o))
          ret i;
    ret -1;
  }
  
  public bool containsKey(O o) {
    ret find(o) >= 0;
  }
  
  @Override
  public B get(O o) {
    int i = find(o);
    ret i >= 0 ? (B) entries[i+1] : null;
  }
}