Learning Haskell with Chess

(Difference between revisions)

Revision as of 08:33, 19 March 2007

This page is about learning Haskell using the board game Chess as a running example. The complete code can be found at http://www.steffen-mazanek.de/dateien/projekte/hsChess.zip.

Define data types that represent boards (
Board
), squares (
Square
), positions (
Pos
), pieces (
Piece
, supported by
PieceColor
and
PieceType
) and game states (
State
).
- Helium: Implement suited eq and show functions.
- Haskell: Define/derive instances of
  Show
  and
  Eq
Implement a function
prettyBoard::Board->String
, that transforms a board into a clearly arranged string representation (human readable :-)). Support this function with auxiliary functions that pretty print pieces, squares, ...
Define the initial board (
initialBoard::Board
), test prettyBoard with initialBoard.
Implement a simple evaluation function
evalBoard::Board->Int
as the difference of material on board (values: Pawn->1, Knight and Bishop->3, Queen->9, Rook->6, King->"infinity"=1000).

Define a data type that represents a game tree (
GameTree
).
Roughly estimate the number of nodes of the gametree with depth 4.
Define a function
play::Gametree->Int
, that computes the value of a given game tree using the minimax Algorithm.
Implement the function
doMove::State->State
, that choses the (best) next state.

@@ Line 5: / Line 5: @@
 ===Learning targets===
 *recapitulate Haskell types (keywords type and data, product and sum types)
-**Helium: define equality functions (pattern matching)
+**Helium: equality and show functions (pattern matching)
-**Haskell: define instances of type classes Show, Eq
+**Haskell: type classes (<hask>Show</hask>, <hask>Eq</hask>, <hask>deriving</hask>
 *pretty printing
 ===Tasks===
-*Define data types that represent boards (<hask>Board</hask>), squares (<hask>Square</hask>), positions (<hask>Pos</hask>), pieces (<hask>Piece</hask>) and game states (<hask>State</hask>).
+*Define data types that represent boards (<hask>Board</hask>), squares (<hask>Square</hask>), positions (<hask>Pos</hask>), pieces (<hask>Piece</hask>, supported by <hask>PieceColor</hask> and <hask>PieceType</hask>) and game states (<hask>State</hask>).
-*Helium: Implement suited eq-functions.
+**Helium: Implement suited eq and show functions.
+**Haskell: Define/derive instances of <hask>Show</hask> and <hask>Eq</hask>
 *Implement a function <hask>prettyBoard::Board->String</hask>, that transforms a board into a clearly arranged string representation (human readable :-)). Support this function with auxiliary functions that pretty print pieces, squares, ...
 *Define the initial board (<hask>initialBoard::Board</hask>), test prettyBoard with initialBoard.