Equivalence

We can also implement the == operator, since again it makes sense to be able to compare two GridMovement objects:

extension GridMovement 
{ 
  static prefix func -><- (movement: inout GridMovement) 
                                            -> GridMovement 
  { 
    return GridMovement (rows: movement.col, cols: movement.row) 
  } 
} 

These GridMovement objects are usable now as, say, chessboard moves that can be added together, multiplied by an integral number of moves, and compared with each other. Now go write a chess program.

Just kidding.