Data commit

Task/Sleeping-Beauty-problem/Haskell/sleeping-beauty-problem.hs

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+import Data.Monoid   (Sum(..))
+import System.Random (randomIO)
+import Control.Monad (replicateM)
+import Data.Bool     (bool)
+
+data Toss = Heads | Tails deriving Show
+
+anExperiment toss =
+  moreWakenings <>
+  case toss of
+    Heads -> headsOnWaking
+    Tails -> moreWakenings
+  where
+    moreWakenings = (1,0)
+    headsOnWaking = (0,1)
+
+main = do
+  tosses <- map (bool Heads Tails) <$> replicateM 1000000 randomIO
+  let (Sum w, Sum h) = foldMap anExperiment tosses
+  let ratio = fromIntegral h / fromIntegral w
+  putStrLn $ "Ratio: " ++ show ratio