1 files changed, 0 insertions, 122 deletions
diff --git a/lore/System/Random/Shuffle.hs b/lore/System/Random/Shuffle.hs
deleted file mode 100644
index 02cd3e0..0000000
--- a/lore/System/Random/Shuffle.hs
+++ /dev/null
@@ -1,122 +0,0 @@
-{- |
-Module      : System.Random.Shuffle
-Copyright   : (c) 2009 Oleg Kiselyov, Manlio Perillo
-License     : BSD3 (see LICENSE file)
-
-<http://okmij.org/ftp/Haskell/perfect-shuffle.txt>
-
-
-Example:
-
-    import System.Random (newStdGen)
-    import System.Random.Shuffle (shuffle')
-
-    main = do
-      rng <- newStdGen
-      let xs = [1,2,3,4,5]
-      print $ shuffle' xs (length xs) rng
--}
-{-# OPTIONS_GHC -funbox-strict-fields #-}
-
-module System.Random.Shuffle
-  ( shuffle
-  , shuffle'
-  , shuffleM
-  )
-where
-
-import           Data.Function                  ( fix )
-import           System.Random                  ( RandomGen
-                                                , randomR
-                                                )
-import           Control.Monad                  ( liftM
-                                                , liftM2
-                                                )
-import           Control.Monad.Random           ( MonadRandom
-                                                , getRandomR
-                                                )
-
-
--- | A complete binary tree, of leaves and internal nodes.
--- Internal node: Node card l r
--- where card is the number of leaves under the node.
--- Invariant: card >=2. All internal tree nodes are always full.
-data Tree a = Leaf !a
-            | Node !Int !(Tree a) !(Tree a)
-              deriving Show
-
-
--- | Convert a sequence (e1...en) to a complete binary tree
-buildTree :: [a] -> Tree a
-buildTree = (fix growLevel) . (map Leaf)
- where
-  growLevel _    [node] = node
-  growLevel self l      = self $ inner l
-
-  inner []             = []
-  inner [e           ] = [e]
-  inner (e1 : e2 : es) = e1 `seq` e2 `seq` (join e1 e2) : inner es
-
-  join l@(Leaf _      ) r@(Leaf _      ) = Node 2 l r
-  join l@(Node ct _ _ ) r@(Leaf _      ) = Node (ct + 1) l r
-  join l@(Leaf _      ) r@(Node ct  _ _) = Node (ct + 1) l r
-  join l@(Node ctl _ _) r@(Node ctr _ _) = Node (ctl + ctr) l r
-
-
--- |Given a sequence (e1,...en) to shuffle, and a sequence
--- (r1,...r[n-1]) of numbers such that r[i] is an independent sample
--- from a uniform random distribution [0..n-i], compute the
--- corresponding permutation of the input sequence.
-shuffle :: [a] -> [Int] -> [a]
-shuffle elements = shuffleTree (buildTree elements)
- where
-  shuffleTree (Leaf e) [] = [e]
-  shuffleTree tree (r : rs) =
-    let (b, rest) = extractTree r tree in b : (shuffleTree rest rs)
-  shuffleTree _ _ = error "[shuffle] called with lists of different lengths"
-
-  -- Extracts the n-th element from the tree and returns
-  -- that element, paired with a tree with the element
-  -- deleted.
-  -- The function maintains the invariant of the completeness
-  -- of the tree: all internal nodes are always full.
-  extractTree 0 (Node _ (Leaf e) r       ) = (e, r)
-  extractTree 1 (Node 2 (Leaf l) (Leaf r)) = (r, Leaf l)
-  extractTree n (Node c (Leaf l) r) =
-    let (e, r') = extractTree (n - 1) r in (e, Node (c - 1) (Leaf l) r')
-
-  extractTree n (Node n' l (Leaf e)) | n + 1 == n' = (e, l)
-
-  extractTree n (Node c l@(Node cl _ _) r)
-    | n < cl
-    = let (e, l') = extractTree n l in (e, Node (c - 1) l' r)
-    | otherwise
-    = let (e, r') = extractTree (n - cl) r in (e, Node (c - 1) l r')
-  extractTree _ _ = error "[extractTree] impossible"
-
--- |Given a sequence (e1,...en) to shuffle, its length, and a random
--- generator, compute the corresponding permutation of the input
--- sequence.
-shuffle' :: RandomGen gen => [a] -> Int -> gen -> [a]
-shuffle' elements len = shuffle elements . rseq len
- where
-      -- The sequence (r1,...r[n-1]) of numbers such that r[i] is an
-      -- independent sample from a uniform random distribution
-      -- [0..n-i]
-  rseq :: RandomGen gen => Int -> gen -> [Int]
-  rseq n = fst . unzip . rseq' (n - 1)
-   where
-    rseq' :: RandomGen gen => Int -> gen -> [(Int, gen)]
-    rseq' 0 _   = []
-    rseq' i gen = (j, gen) : rseq' (i - 1) gen'
-      where (j, gen') = randomR (0, i) gen
-
--- |shuffle' wrapped in a random monad
-shuffleM :: (MonadRandom m) => [a] -> m [a]
-shuffleM elements
-  | null elements = return []
-  | otherwise     = liftM (shuffle elements) (rseqM (length elements - 1))
- where
-  rseqM :: (MonadRandom m) => Int -> m [Int]
-  rseqM 0 = return []
-  rseqM i = liftM2 (:) (getRandomR (0, i)) (rseqM (i - 1))