// a persistent list using a clever combination of persisting and logging

// (well, only logging as of now)

// Note: don't put in static initializer (programID not set yet)

static class PersistentList<A> extends AbstractList<A> {

  new List<A> m;

  File file;

  PersistentList(S fileName) {

    this(getProgramFile(fileName));

  }

  PersistentList(S progID, S fileName) {

    this(getProgramFile(progID, fileName));

  }

  *(File *file) {

    for (S s : scanLog(file)) pcall {

      L l = cast unstructure(s);

      if (eq(l.get(0), "add"))

        m.put((A) l.get(1), (B) l.get(2));

      else if (eq(l.get(0), "remove"))

        m.remove((A) l.get(1));

      else

        print("Unknown command in log: " + l.get(0));

    }

  }

  // just delegates

  public int size() {

    ret m.size();

  }

  public B get(int i) {

    ret m.get(i);

  }

  // TODO: calling remove() in the iterator will have unpersisted

  // effects.

  public Set<Map.Entry<A,B>> entrySet() {

    ret m.entrySet();

  }

  // delegates with logging

  public B put(A a, B b) {

    B result = m.put(a, b);

    logQuoted(file, structure(litlist("add", a, b)));

    ret result;

  }

  public B remove(O a) {

    B result = m.remove(a);

    logQuoted(file, structure(litlist("remove", a)));

    ret result;

  }

}