sclass Attractor implements IAttractor, Runnable {
  F1<S, Bool> tester;
  Runnable action;
  S input; // when matched

  *() {}
  *(F1<S, Bool> *tester, Runnable *action) {}
  *(Runnable *action) {}
  
  public bool matches(S s) {
    ret isTrue(callF(tester, s));
  }
  
  public void run {
    callF(action);
  }
  
  toString { ret standard_toString(this); }
  
  bool matches_public(S s) {
    ret false if !matches(s);
    ret true with a.input = input;
  }
}

sclass DefaultAttractor > Attractor {
  *() { this(null); }
  *(Runnable *action) { tester = f1_true(); }
}

sclass MatchAttractor > Attractor {
  S pattern;
  
  *() {}
  *(S *pattern) {}
  *(S *pattern, Runnable *action) {}
  
  public bool matches(S s) {
    ret matchX2(pattern, s);
  }
}

sclass YesAttractor > Attractor {
  *() {
    tester = f<S, Bool> isYes_1;
  }
  
  *(Runnable action) { this(); this.action = action; }
}