General game solver in Haskell

Games are instances of the class GameState. The minimal complete definition for this class must implement the following function:

• player - the player whose current turn it is (either Maximizer or Minimizer).
• terminal - this must be set to Nothing for all terminal nodes, and to Just val where val is the outcome of the game.
• actions - these is a list of pairs (name, result) where name is the move's name, and branch is the is sub branch of the game that is reached with the move.

All instances of GameState are also Show, and their show value is a presentation of the game's state to the user.

Better documentation will perhaps happen some day in the future.