One of the authors thinks this is a good example of what can be achieved in a simple way using TDL. The other author thinks this example is a bridge too far in using component composition. Therefore, we entered this puzzle as a challenge for improvement and as a pun on the title of this chapter.
The example we are going to describe is an implementation of a puzzle you all know from childhood: the 15 square puzzle.
The puzzle has a 4 x 4 square board with 15 ...