no need to set winner until game is over

combinators.nim

@@ -1,5 +1,5 @@
 import algorithm, random, sugar
-import fastrand, fixedseq, game
+import fixedseq, game
 
 
 proc nextPermutation(x: var FixedSeq): bool =
@@ -93,4 +93,4 @@ proc randomFuture*(dice: FixedSeq, r: var Rand): FixedSeq[5, Die, int8] =
   result.initFixedSeq
   let order = dice.dup(shuffle(r))
   for i, color in order:
-    result.add((color, r.fastRand(1..3)))
+    result.add((color, r.rand(1..3)))

fastrand.nim

@@ -1,74 +0,0 @@
-import random, math
-import times, std/monotimes, strformat, strutils
-
-
-proc formatNum(n: SomeNumber): string =
-  let s = $(n.round)
-  let t = s[0 .. s.len - 3]
-  var count = 1
-  for i in countdown(t.high, 0):
-    result.insert($t[i], 0)
-    if count mod 3 == 0 and i != 0:
-      result.insert(",", 0)
-    count += 1
-
-
-proc formatRate(n: Natural, d: Duration): string =
-  result = formatNum(1_000_000'f64 * n.float64 / d.inMicroseconds.float64)
-
-
-const upperBound = uint64(uint32.high)
-
-
-proc fastRand*[T: Natural](r: var Rand, x: T): T =
-  # Nim ranges are usually inclusive, but this algorithm is exclusive
-  let x = x.uint64 + 1
-  let num = if x <= upperBound:
-    ((r.next shr 32) * x.uint64) shr 32
-  else:
-    r.next mod x.uint64
-  result = T(num)
-
-
-proc fastRand*(r: var Rand; x, y: Natural): Natural =
-  let lim = (y - x)
-  result = fastRand(r, lim) + x
-
-
-proc fastRand*[T](r: var Rand, slice: HSlice[T, T]): T =
-  let n = fastRand(r, slice.a.Natural, slice.b.Natural)
-  result = T(n)
-
-
-proc testFastRand(num = 1_000_000_000): Duration =
-  var r = initRand(rand(int64))
-  let start = getMonoTime()
-  for i in 1 .. num:
-    discard r.fastRand(5)
-  result = getMonoTime() - start
-  # echo "fastrand execution rate: ",  1000 * num / dur.inMilliseconds.int, " generated per second."
-
-
-proc testStdRand(num = 1_000_000_000): Duration =
-  var r = initRand(rand(int64))
-  let start = getMonoTime()
-  for i in 1 .. num:
-    discard r.rand(4)
-  result = getMonoTime() - start
-  # echo "std rand execution rate: ", 1000 * num / dur.inMilliseconds.int, " generated per second."
-
-
-when isMainModule:
-  randomize()
-  var r = initRand(rand(int64))
-  let runs = 100_000_000
-  var totals: array[5..9, int]
-  for i in 1 .. runs:
-    let n = r.fastRand(5..9)
-    totals[n] += 1
-  echo totals
-
-  # let fr = testFastRand(runs)
-  # echo "fastrand execution rate: ", formatNum(1_000_000 * runs / fr.inMicroseconds.int)
-  # let sr = testStdRand(runs)
-  # echo "standard execution rate: ", formatNum(1_000_000 * runs / sr.inMicroseconds.int)

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()