no need to track leader until game is over

game.nim

@@ -57,7 +57,7 @@ type
     squares*: array[1..16, Square]
     camels*: array[Color, range[1..16]]
     diceRolled*: array[Color, bool]
-    leader*: Option[Color]
+    winner*: Option[Color]
     gameOver*: bool
     initialized: bool
 
@@ -66,6 +66,10 @@ type
 template `[]`*[T](b: var Board, idx: T): var Square =
   b.squares[idx]
 
+# apparently we need separate ones for mutable and non-mutable
+template `[]`*[T](b: Board, idx: T): Square =
+  b.squares[idx]
+
 
 proc hash*(b: Board): Hash =
   var h: Hash = 0
@@ -87,6 +91,11 @@ proc init*(b: var Board) =
   b.initialized = true
 
 
+proc leader*(b: Board): Color =
+  let leadSquare = max(b.camels)
+  result = b[leadSquare].camels[^1]
+
+
 proc display*(b: Board, start, stop: int) =
   for i in start..stop:
     let sq = b.squares[i]
@@ -108,9 +117,6 @@ proc setState*(b: var Board;
   for (tile, dest) in tiles:
     b[dest].tile = some(tile)
 
-  let leadCamel = b[max(b.camels)].camels[^1] # top camel in the last currently-occupied space
-  b.leader = some(leadCamel)
-
 
 proc diceRemaining*(b: Board): ColorStack =
   result.initFixedSeq
@@ -119,7 +125,7 @@ proc diceRemaining*(b: Board): ColorStack =
 
 
 proc resetDice*(b: var Board) =
-  for c, rolled in b.diceRolled:
+  for c in Color:
     b.diceRolled[c] = false
 
 
@@ -130,7 +136,7 @@ proc advance*(b: var Board, die: Die) =
   var endPos = startPos + roll
   
   if endPos > 16: # camel has passed the finish line
-    b.leader = some(b[startPos].camels[^1])
+    b.winner = some(b[startPos].camels[^1])
     b.gameOver = true
     return
 
@@ -154,8 +160,4 @@ proc advance*(b: var Board, die: Die) =
     for i in (dstPrevHigh + 1) .. b[endPos].camels.high:
       b.camels[b[endPos].camels[i]] = endPos
   
-  # if we are stacking on or moving past the previous leader
-  if endPos >= b.camels[b.leader.get]:
-    b.leader = some(b[endPos].camels[^1])
-  
   b.diceRolled[color] = true

simulation.nim

@@ -52,7 +52,7 @@ iterator legEndStates(b: Board): Board =
 
 proc getLegScores*(b: Board): ScoreSet =
   for prediction in b.legEndStates:
-    inc result[prediction.leader.get]
+    inc result[prediction.winner.get]
 
 
 # =====================
@@ -65,7 +65,7 @@ proc randomGame*(b: Board, r: var Rand): Color =
     for roll in randomFuture(projection.diceRemaining, r):
       projection.advance(roll)
       if projection.gameOver:
-        return projection.leader.get
+        return projection.winner.get
     projection.resetDice()