persistable sclass IntArrayBitMatrix extends AbstractMatrix<Bool> is BitMatrix {
  int[] data;
  
  *(int *w, int *h) { data = new int[arrayLength()]; }
  *(int *w, int *h, int[] *data) {}
  
  int arrayLength() { ret (w*h+31)/32; }
  static int arrayLength(int w, int h) { ret (w*h+31)/32; }

  public Bool get(int x, int y) {
    try {
      ret getBitFromIntArray_littleEndian(data, y*w+x);
    } catch e {
      fail(e, "Access out of bounds", +x, +y, +w, +h);
    }
  }
  
  public void set(int x, int y, Bool a default true) { setBitInIntArray_littleEndian(data, y*w+x, a); }
}

Began life as a copy of #1033581