Clean up; use proper INF for alpha/beta

README.md

@@ -26,7 +26,7 @@ The bulk of the work is in making the game itself. See the _turn_based_game_ lib
 * turn_based_game (repo): <https://github.com/JohnAD/turn_based_game>
 * turn_based_game (docs): <https://github.com/JohnAD/turn_based_game/wiki>
 
-Once made, simply import the negamax library and use a `NegamaxPlayer` instead of a normal `Player`. Include the `depth` of the search as an object parameter. The depth is measured in **plies**. One **ply** is a single turn. So, a round of play between two players is two plies.
+Once made, simply import the negamax library and use a `NegamaxPlayer` instead of a normal `Player`. Include the `depth` of the search as an object parameter. The depth is measured in **plies**. One **ply** is a single play. So, one full round of play between two players is two plies.
 
 The Negamax AI specifically requires that the
 

examples/knights_with_negamax.nim → examples/knights_human_vs_negamax.nim

@@ -1,6 +1,6 @@
 import turn_based_game
 import knights
-import "../src/negamax"
+import negamax
 import strutils
 
 const

src/negamax.nim

@@ -3,9 +3,6 @@ import tables
 import turn_based_game
 
 
-let INF = 999999.9
-let NEGINF = -999999.9
-
 proc negamax_core(game: var Game, ai_choice: var string, depth: int, orig_depth: int, alpha_in: float, beta_in: float): float =
 
   var
@@ -36,7 +33,7 @@ proc negamax_core(game: var Game, ai_choice: var string, depth: int, orig_depth:
   # set up defaults/fall-throughs
   #
   var best_move = possible_moves[0]
-  var best_value = NEGINF
+  var best_value = -INF
 
   for move in possible_moves:
 
@@ -81,7 +78,7 @@ proc negamax*(game: var Game, depth: int): string =
     ai_choice: string
     possible_moves: seq[string] = @[]
 
-  alpha = NEGINF
+  alpha = -INF
   beta = INF
 
 
@@ -107,8 +104,6 @@ type
   NegamaxPlayer* = ref object of Player
     depth*: int
 
-
-# TODO: verify that default depth=0 works-ish
 #
 method get_move*(self: NegamaxPlayer, game: Game): string = 
   var new_game: Game