Editing Learning Haskell with Chess (section)

==Exercise 2 - move generator==
===Learning targets===
*list comprehension
*stepwise refinement
===Tasks===
*Define a function <hask>movePos::Pos->Pos->Board->Board</hask> such that <hask>movePos p1 p2 b</hask> moves the piece at p1 to p2 (overwrite the square at p2 with the square at p1 and delete p1). Do not check whether the move is valid at this stage. Hint: Define a function <hask>updateBoard</hask> first. On top of this further define a function <hask>deleteSquare</hask>. Its much simpler to have these functions at hand.
*Implement a function <hask>colorPos::PieceColor->Board->[Pos]</hask> whose result is the list of the positions of the pieces of a certain color.
*Define <hask>moves::PieceType->[(Int,Int)]</hask> that returns the base moving vectors for a particular piece (return empty list for pawns here, because their vector depends on the color).
*Implement <hask>genMoves::Board->Pos->[Board]</hask>, it takes a board b and a position p and results in the list of all boards that may follow if you move the piece at p on board b.
*Combine <hask>colorPos</hask> and <hask>genMoves</hask> to a function <hask>nextStates::State->[State]</hask> that returns all possible successor states.