{-# LANGUAGE CPP                   #-}
{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE MagicHash             #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE ScopedTypeVariables   #-}
{-# LANGUAGE TypeFamilies          #-}
{-# LANGUAGE UnboxedTuples         #-}
-- |
-- Module     : System.Random.PCG.Class
-- Copyright  : Copyright (c) 2014-2015, Christopher Chalmers <c.chalmers@me.com>
-- License    : BSD3
-- Maintainer : Christopher Chalmers <c.chalmers@me.com>
-- Stability  : experimental
-- Portability: CPP
--
-- Classes for working with random numbers along with utility functions.
-- In a future release this module may disappear and use another module
-- for this functionality.
module System.Random.PCG.Class
  ( -- * Classes
    Generator (..)
  , Variate (..)

    -- * Type restricted versions
    -- ** uniform
  , uniformW8, uniformW16, uniformW32, uniformW64
  , uniformI8, uniformI16, uniformI32, uniformI64
  , uniformF, uniformD, uniformBool

    -- ** uniformR
  , uniformRW8, uniformRW16, uniformRW32, uniformRW64
  , uniformRI8, uniformRI16, uniformRI32, uniformRI64
  , uniformRF, uniformRD, uniformRBool

    -- ** uniformB
  , uniformBW8, uniformBW16, uniformBW32, uniformBW64
  , uniformBI8, uniformBI16, uniformBI32, uniformBI64
  , uniformBF, uniformBD, uniformBBool

   -- * Utilities
  , Unsigned
  , wordsTo64Bit
  , wordToBool
  , wordToFloat
  , wordsToDouble
  , sysRandom
  ) where

#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
#include "MachDeps.h"
#endif

import Control.Monad
import Data.Bits
import Data.ByteString (useAsCString)
import Data.Int
import Data.Word
import Foreign         (castPtr, peek)
import System.Entropy

class Monad m => Generator g m where
  uniform1 :: (Word32 -> a) -> g -> m a
  uniform2 :: (Word32 -> Word32 -> a) -> g -> m a
  uniform1B :: Integral a => (Word32 -> a) -> Word32 -> g -> m a

class Variate a where
  -- | Generate a uniformly distributed random vairate.
  --
  --   * Use entire range for integral types.
  --
  --   * Use (0,1] range for floating types.
  uniform  :: Generator g m => g -> m a

  -- | Generate a uniformly distributed random vairate in the given
  --   range.
  --
  --   * Use inclusive range for integral types.
  --
  --   * Use (a,b] range for floating types.
  uniformR :: Generator g m => (a,a) -> g -> m a

  -- | Generate a uniformly distributed random vairate in the range
  --   [0,b). For integral types the bound must be less than the max bound
  --   of 'Word32' (4294967295). Behaviour is undefined for negative
  --   bounds.
  uniformB :: Generator g m => a -> g -> m a

------------------------------------------------------------------------
-- Variate instances
------------------------------------------------------------------------

instance Variate Int8 where
  uniform :: g -> m Int8
uniform = (Word32 -> Int8) -> g -> m Int8
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> a) -> g -> m a
uniform1 Word32 -> Int8
forall a b. (Integral a, Num b) => a -> b
fromIntegral
  {-# INLINE uniform  #-}
  uniformR :: (Int8, Int8) -> g -> m Int8
uniformR (Int8, Int8)
a g
g = (Int8, Int8) -> g -> m Int8
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Int8, Int8)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Int8 -> g -> m Int8
uniformB Int8
b g
g = (Word32 -> Int8) -> Word32 -> g -> m Int8
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Int8
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Int8 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Int8
b) g
g
  {-# INLINE uniformB #-}

instance Variate Int16 where
  uniform :: g -> m Int16
uniform  = (Word32 -> Int16) -> g -> m Int16
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> a) -> g -> m a
uniform1 Word32 -> Int16
forall a b. (Integral a, Num b) => a -> b
fromIntegral
  {-# INLINE uniform  #-}
  uniformR :: (Int16, Int16) -> g -> m Int16
uniformR (Int16, Int16)
a g
g = (Int16, Int16) -> g -> m Int16
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Int16, Int16)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Int16 -> g -> m Int16
uniformB Int16
b g
g = (Word32 -> Int16) -> Word32 -> g -> m Int16
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Int16
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Int16 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Int16
b) g
g
  {-# INLINE uniformB #-}

instance Variate Int32 where
  uniform :: g -> m Int32
uniform = (Word32 -> Int32) -> g -> m Int32
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> a) -> g -> m a
uniform1 Word32 -> Int32
forall a b. (Integral a, Num b) => a -> b
fromIntegral
  {-# INLINE uniform  #-}
  uniformR :: (Int32, Int32) -> g -> m Int32
uniformR (Int32, Int32)
a g
g = (Int32, Int32) -> g -> m Int32
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Int32, Int32)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Int32 -> g -> m Int32
uniformB Int32
b g
g = (Word32 -> Int32) -> Word32 -> g -> m Int32
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Int32
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Int32 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Int32
b) g
g
  {-# INLINE uniformB #-}

instance Variate Int64 where
  uniform :: g -> m Int64
uniform = (Word32 -> Word32 -> Int64) -> g -> m Int64
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> Word32 -> a) -> g -> m a
uniform2 Word32 -> Word32 -> Int64
forall a. Integral a => Word32 -> Word32 -> a
wordsTo64Bit
  {-# INLINE uniform  #-}
  uniformR :: (Int64, Int64) -> g -> m Int64
uniformR (Int64, Int64)
a g
g = (Int64, Int64) -> g -> m Int64
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Int64, Int64)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Int64 -> g -> m Int64
uniformB Int64
b g
g = (Word32 -> Int64) -> Word32 -> g -> m Int64
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Int64
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Int64 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Int64
b) g
g
  {-# INLINE uniformB #-}

instance Variate Word8 where
  uniform :: g -> m Word8
uniform = (Word32 -> Word8) -> g -> m Word8
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> a) -> g -> m a
uniform1 Word32 -> Word8
forall a b. (Integral a, Num b) => a -> b
fromIntegral
  {-# INLINE uniform  #-}
  uniformR :: (Word8, Word8) -> g -> m Word8
uniformR (Word8, Word8)
a g
g = (Word8, Word8) -> g -> m Word8
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Word8, Word8)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Word8 -> g -> m Word8
uniformB Word8
b g
g = (Word32 -> Word8) -> Word32 -> g -> m Word8
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Word8
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Word8 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word8
b) g
g
  {-# INLINE uniformB #-}

instance Variate Word16 where
  uniform :: g -> m Word16
uniform = (Word32 -> Word16) -> g -> m Word16
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> a) -> g -> m a
uniform1 Word32 -> Word16
forall a b. (Integral a, Num b) => a -> b
fromIntegral
  {-# INLINE uniform  #-}
  uniformR :: (Word16, Word16) -> g -> m Word16
uniformR (Word16, Word16)
a g
g = (Word16, Word16) -> g -> m Word16
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Word16, Word16)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Word16 -> g -> m Word16
uniformB Word16
b g
g = (Word32 -> Word16) -> Word32 -> g -> m Word16
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Word16
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Word16 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word16
b) g
g
  {-# INLINE uniformB #-}

instance Variate Word32 where
  uniform :: g -> m Word32
uniform = (Word32 -> Word32) -> g -> m Word32
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> a) -> g -> m a
uniform1 Word32 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral
  {-# INLINE uniform  #-}
  uniformR :: (Word32, Word32) -> g -> m Word32
uniformR (Word32, Word32)
a g
g = (Word32, Word32) -> g -> m Word32
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Word32, Word32)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Word32 -> g -> m Word32
uniformB Word32
b g
g = (Word32 -> Word32) -> Word32 -> g -> m Word32
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Word32 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word32
b) g
g
  {-# INLINE uniformB #-}

instance Variate Word64 where
  uniform :: g -> m Word64
uniform = (Word32 -> Word32 -> Word64) -> g -> m Word64
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> Word32 -> a) -> g -> m a
uniform2 Word32 -> Word32 -> Word64
forall a. Integral a => Word32 -> Word32 -> a
wordsTo64Bit
  {-# INLINE uniform  #-}
  uniformR :: (Word64, Word64) -> g -> m Word64
uniformR (Word64, Word64)
a g
g = (Word64, Word64) -> g -> m Word64
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Word64, Word64)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Word64 -> g -> m Word64
uniformB Word64
b g
g = (Word32 -> Word64) -> Word32 -> g -> m Word64
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Word64
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Word64 -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word64
b) g
g
  {-# INLINE uniformB #-}

instance Variate Bool where
  uniform :: g -> m Bool
uniform = (Word32 -> Bool) -> g -> m Bool
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> a) -> g -> m a
uniform1 Word32 -> Bool
wordToBool
  {-# INLINE uniform  #-}
  uniformR :: (Bool, Bool) -> g -> m Bool
uniformR (Bool
False,Bool
True)  g
g = g -> m Bool
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g
  uniformR (Bool
False,Bool
False) g
_ = Bool -> m Bool
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False
  uniformR (Bool
True,Bool
True)   g
_ = Bool -> m Bool
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
True
  uniformR (Bool
True,Bool
False)  g
g = g -> m Bool
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g
  {-# INLINE uniformR #-}
  uniformB :: Bool -> g -> m Bool
uniformB Bool
False g
_ = Bool -> m Bool
forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False
  uniformB Bool
_     g
g = g -> m Bool
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g
  {-# INLINE uniformB #-}

instance Variate Float where
  uniform :: g -> m Float
uniform = (Word32 -> Float) -> g -> m Float
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> a) -> g -> m a
uniform1 Word32 -> Float
wordToFloat
  {-# INLINE uniform  #-}
  uniformR :: (Float, Float) -> g -> m Float
uniformR (Float
x1,Float
x2) = (Word32 -> Float) -> g -> m Float
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> a) -> g -> m a
uniform1 (\Word32
w -> Float
x1 Float -> Float -> Float
forall a. Num a => a -> a -> a
+ (Float
x2Float -> Float -> Float
forall a. Num a => a -> a -> a
-Float
x1) Float -> Float -> Float
forall a. Num a => a -> a -> a
* Word32 -> Float
wordToFloat Word32
w)
  {-# INLINE uniformR #-}
  -- subtract 2**(-33) to go from (0,b] to [0,b) (I think)
  uniformB :: Float -> g -> m Float
uniformB Float
b g
g = (Float -> Float -> Float
forall a. Num a => a -> a -> a
subtract Float
1.16415321826934814453125e-10) (Float -> Float) -> m Float -> m Float
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` (Float, Float) -> g -> m Float
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (Float
0,Float
b) g
g
  {-# INLINE uniformB #-}

instance Variate Double where
  uniform :: g -> m Double
uniform = (Word32 -> Word32 -> Double) -> g -> m Double
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> Word32 -> a) -> g -> m a
uniform2 Word32 -> Word32 -> Double
wordsToDouble
  {-# INLINE uniform  #-}
  uniformR :: (Double, Double) -> g -> m Double
uniformR (Double
x1,Double
x2) = (Word32 -> Word32 -> Double) -> g -> m Double
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> Word32 -> a) -> g -> m a
uniform2 (\Word32
w1 Word32
w2 -> Double
x1 Double -> Double -> Double
forall a. Num a => a -> a -> a
+ (Double
x2Double -> Double -> Double
forall a. Num a => a -> a -> a
-Double
x1) Double -> Double -> Double
forall a. Num a => a -> a -> a
* Word32 -> Word32 -> Double
wordsToDouble Word32
w1 Word32
w2)
  {-# INLINE uniformR #-}
  -- subtract 2**(-53) to go from (0,b] to [0,b) (I think)
  uniformB :: Double -> g -> m Double
uniformB Double
b g
g = (Double -> Double -> Double
forall a. Num a => a -> a -> a
subtract Double
1.1102230246251565404236316680908203125e-16) (Double -> Double) -> m Double -> m Double
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` (Double, Double) -> g -> m Double
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (Double
0,Double
b) g
g
  {-# INLINE uniformB #-}

instance Variate Word where
#if WORD_SIZE_IN_BITS < 64
  uniform = uniform1 fromIntegral
#else
  uniform :: g -> m Word
uniform = (Word32 -> Word32 -> Word) -> g -> m Word
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> Word32 -> a) -> g -> m a
uniform2 Word32 -> Word32 -> Word
forall a. Integral a => Word32 -> Word32 -> a
wordsTo64Bit
#endif
  {-# INLINE uniform  #-}
  uniformR :: (Word, Word) -> g -> m Word
uniformR (Word, Word)
a g
g = (Word, Word) -> g -> m Word
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Word, Word)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Word -> g -> m Word
uniformB Word
b g
g = (Word32 -> Word) -> Word32 -> g -> m Word
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Word
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Word -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word
b) g
g
  {-# INLINE uniformB #-}

instance Variate Int where
#if WORD_SIZE_IN_BITS < 64
  uniform = uniform1 fromIntegral
#else
  uniform :: g -> m Int
uniform = (Word32 -> Word32 -> Int) -> g -> m Int
forall g (m :: * -> *) a.
Generator g m =>
(Word32 -> Word32 -> a) -> g -> m a
uniform2 Word32 -> Word32 -> Int
forall a. Integral a => Word32 -> Word32 -> a
wordsTo64Bit
#endif
  {-# INLINE uniform  #-}
  uniformR :: (Int, Int) -> g -> m Int
uniformR (Int, Int)
a g
g = (Int, Int) -> g -> m Int
forall g (m :: * -> *) a.
(Generator g m, Integral a, Variate a, Integral (Unsigned a),
 Bounded (Unsigned a), Variate (Unsigned a)) =>
(a, a) -> g -> m a
uniformRange (Int, Int)
a g
g
  {-# INLINE uniformR #-}
  uniformB :: Int -> g -> m Int
uniformB Int
b g
g = (Word32 -> Int) -> Word32 -> g -> m Int
forall g (m :: * -> *) a.
(Generator g m, Integral a) =>
(Word32 -> a) -> Word32 -> g -> m a
uniform1B Word32 -> Int
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Int -> Word32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Int
b) g
g
  {-# INLINE uniformB #-}

instance (Variate a, Variate b) => Variate (a,b) where
  uniform :: g -> m (a, b)
uniform g
g = (,) (a -> b -> (a, b)) -> m a -> m (b -> (a, b))
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` g -> m a
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g m (b -> (a, b)) -> m b -> m (a, b)
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` g -> m b
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g
  {-# INLINE uniform  #-}
  uniformR :: ((a, b), (a, b)) -> g -> m (a, b)
uniformR ((a
x1,b
y1),(a
x2,b
y2)) g
g = (,) (a -> b -> (a, b)) -> m a -> m (b -> (a, b))
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` (a, a) -> g -> m a
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (a
x1,a
x2) g
g m (b -> (a, b)) -> m b -> m (a, b)
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` (b, b) -> g -> m b
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (b
y1,b
y2) g
g
  {-# INLINE uniformR #-}
  uniformB :: (a, b) -> g -> m (a, b)
uniformB (a
b1,b
b2) g
g = (,) (a -> b -> (a, b)) -> m a -> m (b -> (a, b))
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` a -> g -> m a
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB a
b1 g
g m (b -> (a, b)) -> m b -> m (a, b)
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` b -> g -> m b
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB b
b2 g
g
  {-# INLINE uniformB #-}

instance (Variate a, Variate b, Variate c) => Variate (a,b,c) where
  uniform :: g -> m (a, b, c)
uniform g
g = (,,) (a -> b -> c -> (a, b, c)) -> m a -> m (b -> c -> (a, b, c))
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` g -> m a
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g m (b -> c -> (a, b, c)) -> m b -> m (c -> (a, b, c))
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` g -> m b
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g m (c -> (a, b, c)) -> m c -> m (a, b, c)
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` g -> m c
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g
  {-# INLINE uniform  #-}
  uniformR :: ((a, b, c), (a, b, c)) -> g -> m (a, b, c)
uniformR ((a
x1,b
y1,c
z1),(a
x2,b
y2,c
z2)) g
g =
    (,,) (a -> b -> c -> (a, b, c)) -> m a -> m (b -> c -> (a, b, c))
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` (a, a) -> g -> m a
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (a
x1,a
x2) g
g m (b -> c -> (a, b, c)) -> m b -> m (c -> (a, b, c))
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` (b, b) -> g -> m b
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (b
y1,b
y2) g
g m (c -> (a, b, c)) -> m c -> m (a, b, c)
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` (c, c) -> g -> m c
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (c
z1,c
z2) g
g
  {-# INLINE uniformR #-}
  uniformB :: (a, b, c) -> g -> m (a, b, c)
uniformB (a
b1,b
b2,c
b3) g
g = (,,) (a -> b -> c -> (a, b, c)) -> m a -> m (b -> c -> (a, b, c))
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` a -> g -> m a
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB a
b1 g
g m (b -> c -> (a, b, c)) -> m b -> m (c -> (a, b, c))
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` b -> g -> m b
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB b
b2 g
g m (c -> (a, b, c)) -> m c -> m (a, b, c)
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` c -> g -> m c
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB c
b3 g
g
  {-# INLINE uniformB #-}

instance (Variate a, Variate b, Variate c, Variate d) => Variate (a,b,c,d) where
  uniform :: g -> m (a, b, c, d)
uniform g
g = (,,,) (a -> b -> c -> d -> (a, b, c, d))
-> m a -> m (b -> c -> d -> (a, b, c, d))
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` g -> m a
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g m (b -> c -> d -> (a, b, c, d))
-> m b -> m (c -> d -> (a, b, c, d))
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` g -> m b
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g m (c -> d -> (a, b, c, d)) -> m c -> m (d -> (a, b, c, d))
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` g -> m c
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g m (d -> (a, b, c, d)) -> m d -> m (a, b, c, d)
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` g -> m d
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g
  {-# INLINE uniform  #-}
  uniformR :: ((a, b, c, d), (a, b, c, d)) -> g -> m (a, b, c, d)
uniformR ((a
x1,b
y1,c
z1,d
t1),(a
x2,b
y2,c
z2,d
t2)) g
g =
    (,,,) (a -> b -> c -> d -> (a, b, c, d))
-> m a -> m (b -> c -> d -> (a, b, c, d))
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` (a, a) -> g -> m a
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (a
x1,a
x2) g
g m (b -> c -> d -> (a, b, c, d))
-> m b -> m (c -> d -> (a, b, c, d))
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` (b, b) -> g -> m b
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (b
y1,b
y2) g
g m (c -> d -> (a, b, c, d)) -> m c -> m (d -> (a, b, c, d))
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap`
                  (c, c) -> g -> m c
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (c
z1,c
z2) g
g m (d -> (a, b, c, d)) -> m d -> m (a, b, c, d)
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` (d, d) -> g -> m d
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR (d
t1,d
t2) g
g
  {-# INLINE uniformR #-}
  uniformB :: (a, b, c, d) -> g -> m (a, b, c, d)
uniformB (a
b1,b
b2,c
b3,d
b4) g
g = (,,,) (a -> b -> c -> d -> (a, b, c, d))
-> m a -> m (b -> c -> d -> (a, b, c, d))
forall (m :: * -> *) a1 r. Monad m => (a1 -> r) -> m a1 -> m r
`liftM` a -> g -> m a
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB a
b1 g
g m (b -> c -> d -> (a, b, c, d))
-> m b -> m (c -> d -> (a, b, c, d))
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` b -> g -> m b
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB b
b2 g
g m (c -> d -> (a, b, c, d)) -> m c -> m (d -> (a, b, c, d))
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` c -> g -> m c
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB c
b3 g
g m (d -> (a, b, c, d)) -> m d -> m (a, b, c, d)
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
`ap` d -> g -> m d
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB d
b4 g
g
  {-# INLINE uniformB #-}

------------------------------------------------------------------------
-- Type restricted versions
------------------------------------------------------------------------

-- uniform -------------------------------------------------------------

uniformI8 :: Generator g m => g -> m Int8
uniformI8 :: g -> m Int8
uniformI8 = g -> m Int8
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformI8 #-}

uniformI16 :: Generator g m => g -> m Int16
uniformI16 :: g -> m Int16
uniformI16 = g -> m Int16
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformI16 #-}

uniformI32 :: Generator g m => g -> m Int32
uniformI32 :: g -> m Int32
uniformI32 = g -> m Int32
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformI32 #-}

uniformI64 :: Generator g m => g -> m Int64
uniformI64 :: g -> m Int64
uniformI64 = g -> m Int64
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformI64 #-}

uniformW8 :: Generator g m => g -> m Word8
uniformW8 :: g -> m Word8
uniformW8 = g -> m Word8
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformW8 #-}

uniformW16 :: Generator g m => g -> m Word16
uniformW16 :: g -> m Word16
uniformW16 = g -> m Word16
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformW16 #-}

uniformW32 :: Generator g m => g -> m Word32
uniformW32 :: g -> m Word32
uniformW32 = g -> m Word32
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformW32 #-}

uniformW64 :: Generator g m => g -> m Word64
uniformW64 :: g -> m Word64
uniformW64 = g -> m Word64
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformW64 #-}

uniformBool :: Generator g m => g -> m Bool
uniformBool :: g -> m Bool
uniformBool = g -> m Bool
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformBool #-}

uniformF :: Generator g m => g -> m Float
uniformF :: g -> m Float
uniformF = g -> m Float
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformF #-}

uniformD :: Generator g m => g -> m Double
uniformD :: g -> m Double
uniformD = g -> m Double
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform
{-# INLINE uniformD #-}

-- uniformR ------------------------------------------------------------

uniformRI8 :: Generator g m => (Int8, Int8) -> g -> m Int8
uniformRI8 :: (Int8, Int8) -> g -> m Int8
uniformRI8 = (Int8, Int8) -> g -> m Int8
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRI8 #-}

uniformRI16 :: Generator g m => (Int16, Int16) -> g -> m Int16
uniformRI16 :: (Int16, Int16) -> g -> m Int16
uniformRI16 = (Int16, Int16) -> g -> m Int16
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRI16 #-}

uniformRI32 :: Generator g m => (Int32, Int32) -> g -> m Int32
uniformRI32 :: (Int32, Int32) -> g -> m Int32
uniformRI32 = (Int32, Int32) -> g -> m Int32
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRI32 #-}

uniformRI64 :: Generator g m => (Int64, Int64) -> g -> m Int64
uniformRI64 :: (Int64, Int64) -> g -> m Int64
uniformRI64 = (Int64, Int64) -> g -> m Int64
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRI64 #-}

uniformRW8 :: Generator g m => (Word8, Word8) -> g -> m Word8
uniformRW8 :: (Word8, Word8) -> g -> m Word8
uniformRW8 = (Word8, Word8) -> g -> m Word8
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRW8 #-}

uniformRW16 :: Generator g m => (Word16, Word16) -> g -> m Word16
uniformRW16 :: (Word16, Word16) -> g -> m Word16
uniformRW16 = (Word16, Word16) -> g -> m Word16
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRW16 #-}

uniformRW32 :: Generator g m => (Word32, Word32) -> g -> m Word32
uniformRW32 :: (Word32, Word32) -> g -> m Word32
uniformRW32 = (Word32, Word32) -> g -> m Word32
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRW32 #-}

uniformRW64 :: Generator g m => (Word64, Word64) -> g -> m Word64
uniformRW64 :: (Word64, Word64) -> g -> m Word64
uniformRW64 = (Word64, Word64) -> g -> m Word64
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRW64 #-}

uniformRBool :: Generator g m => (Bool, Bool) -> g -> m Bool
uniformRBool :: (Bool, Bool) -> g -> m Bool
uniformRBool = (Bool, Bool) -> g -> m Bool
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRBool #-}

uniformRF :: Generator g m => (Float, Float) -> g -> m Float
uniformRF :: (Float, Float) -> g -> m Float
uniformRF = (Float, Float) -> g -> m Float
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRF #-}

uniformRD :: Generator g m => (Double, Double) -> g -> m Double
uniformRD :: (Double, Double) -> g -> m Double
uniformRD = (Double, Double) -> g -> m Double
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
(a, a) -> g -> m a
uniformR
{-# INLINE uniformRD #-}

-- uniformB ------------------------------------------------------------

uniformBI8 :: Generator g m => Int8 -> g -> m Int8
uniformBI8 :: Int8 -> g -> m Int8
uniformBI8 = Int8 -> g -> m Int8
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBI8 #-}

uniformBI16 :: Generator g m => Int16 -> g -> m Int16
uniformBI16 :: Int16 -> g -> m Int16
uniformBI16 = Int16 -> g -> m Int16
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBI16 #-}

uniformBI32 :: Generator g m => Int32 -> g -> m Int32
uniformBI32 :: Int32 -> g -> m Int32
uniformBI32 = Int32 -> g -> m Int32
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBI32 #-}

uniformBI64 :: Generator g m => Int64 -> g -> m Int64
uniformBI64 :: Int64 -> g -> m Int64
uniformBI64 = Int64 -> g -> m Int64
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBI64 #-}

uniformBW8 :: Generator g m => Word8 -> g -> m Word8
uniformBW8 :: Word8 -> g -> m Word8
uniformBW8 = Word8 -> g -> m Word8
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBW8 #-}

uniformBW16 :: Generator g m => Word16 -> g -> m Word16
uniformBW16 :: Word16 -> g -> m Word16
uniformBW16 = Word16 -> g -> m Word16
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBW16 #-}

uniformBW32 :: Generator g m => Word32 -> g -> m Word32
uniformBW32 :: Word32 -> g -> m Word32
uniformBW32 = Word32 -> g -> m Word32
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBW32 #-}

uniformBW64 :: Generator g m => Word64 -> g -> m Word64
uniformBW64 :: Word64 -> g -> m Word64
uniformBW64 = Word64 -> g -> m Word64
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBW64 #-}

uniformBBool :: Generator g m => Bool -> g -> m Bool
uniformBBool :: Bool -> g -> m Bool
uniformBBool = Bool -> g -> m Bool
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBBool #-}

uniformBF :: Generator g m => Float -> g -> m Float
uniformBF :: Float -> g -> m Float
uniformBF = Float -> g -> m Float
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBF #-}

uniformBD :: Generator g m => Double -> g -> m Double
uniformBD :: Double -> g -> m Double
uniformBD = Double -> g -> m Double
forall a g (m :: * -> *).
(Variate a, Generator g m) =>
a -> g -> m a
uniformB
{-# INLINE uniformBD #-}

------------------------------------------------------------------------
-- Utilities
------------------------------------------------------------------------

sub :: (Integral a, Integral (Unsigned a)) => a -> a -> Unsigned a
sub :: a -> a -> Unsigned a
sub a
x a
y = a -> Unsigned a
forall a b. (Integral a, Num b) => a -> b
fromIntegral a
x Unsigned a -> Unsigned a -> Unsigned a
forall a. Num a => a -> a -> a
- a -> Unsigned a
forall a b. (Integral a, Num b) => a -> b
fromIntegral a
y
{-# INLINE sub #-}

add :: (Integral a, Integral (Unsigned a)) => a -> Unsigned a -> a
add :: a -> Unsigned a -> a
add a
m Unsigned a
x = a
m a -> a -> a
forall a. Num a => a -> a -> a
+ Unsigned a -> a
forall a b. (Integral a, Num b) => a -> b
fromIntegral Unsigned a
x
{-# INLINE add #-}

wordsTo64Bit :: Integral a => Word32 -> Word32 -> a
wordsTo64Bit :: Word32 -> Word32 -> a
wordsTo64Bit Word32
x Word32
y =
    Word64 -> a
forall a b. (Integral a, Num b) => a -> b
fromIntegral ((Word32 -> Word64
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word32
x Word64 -> Int -> Word64
forall a. Bits a => a -> Int -> a
`shiftL` Int
32) Word64 -> Word64 -> Word64
forall a. Bits a => a -> a -> a
.|. Word32 -> Word64
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word32
y :: Word64)
{-# INLINE wordsTo64Bit #-}

wordToBool :: Word32 -> Bool
wordToBool :: Word32 -> Bool
wordToBool Word32
i = (Word32
i Word32 -> Word32 -> Word32
forall a. Bits a => a -> a -> a
.&. Word32
1) Word32 -> Word32 -> Bool
forall a. Eq a => a -> a -> Bool
/= Word32
0
{-# INLINE wordToBool #-}

wordToFloat :: Word32 -> Float
wordToFloat :: Word32 -> Float
wordToFloat Word32
x      = (Int32 -> Float
forall a b. (Integral a, Num b) => a -> b
fromIntegral Int32
i Float -> Float -> Float
forall a. Num a => a -> a -> a
* Float
m_inv_32) Float -> Float -> Float
forall a. Num a => a -> a -> a
+ Float
0.5 Float -> Float -> Float
forall a. Num a => a -> a -> a
+ Float
m_inv_33
    where m_inv_33 :: Float
m_inv_33 = Float
1.16415321826934814453125e-10
          m_inv_32 :: Float
m_inv_32 = Float
2.3283064365386962890625e-10
          i :: Int32
i        = Word32 -> Int32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word32
x :: Int32
{-# INLINE wordToFloat #-}

wordsToDouble :: Word32 -> Word32 -> Double
wordsToDouble :: Word32 -> Word32 -> Double
wordsToDouble Word32
x Word32
y  = (Int32 -> Double
forall a b. (Integral a, Num b) => a -> b
fromIntegral Int32
u Double -> Double -> Double
forall a. Num a => a -> a -> a
* Double
m_inv_32 Double -> Double -> Double
forall a. Num a => a -> a -> a
+ (Double
0.5 Double -> Double -> Double
forall a. Num a => a -> a -> a
+ Double
m_inv_53) Double -> Double -> Double
forall a. Num a => a -> a -> a
+
                     Int32 -> Double
forall a b. (Integral a, Num b) => a -> b
fromIntegral (Int32
v Int32 -> Int32 -> Int32
forall a. Bits a => a -> a -> a
.&. Int32
0xFFFFF) Double -> Double -> Double
forall a. Num a => a -> a -> a
* Double
m_inv_52)
    where m_inv_52 :: Double
m_inv_52 = Double
2.220446049250313080847263336181640625e-16
          m_inv_53 :: Double
m_inv_53 = Double
1.1102230246251565404236316680908203125e-16
          m_inv_32 :: Double
m_inv_32 = Double
2.3283064365386962890625e-10
          u :: Int32
u        = Word32 -> Int32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word32
x :: Int32
          v :: Int32
v        = Word32 -> Int32
forall a b. (Integral a, Num b) => a -> b
fromIntegral Word32
y :: Int32
{-# INLINE wordsToDouble #-}

-- IO randoms

-- | Generate a random number using "System.Entropy".
--
--   Use RDRAND if available and XOR with @\/dev\/urandom@ on Unix and
--   CryptAPI on Windows. This entropy is considered cryptographically
--   secure but not true entropy.
sysRandom :: IO Word64
sysRandom :: IO Word64
sysRandom = do
  ByteString
bs <- Int -> IO ByteString
getEntropy Int
8
  ByteString -> (CString -> IO Word64) -> IO Word64
forall a. ByteString -> (CString -> IO a) -> IO a
useAsCString ByteString
bs ((CString -> IO Word64) -> IO Word64)
-> (CString -> IO Word64) -> IO Word64
forall a b. (a -> b) -> a -> b
$ Ptr Word64 -> IO Word64
forall a. Storable a => Ptr a -> IO a
peek (Ptr Word64 -> IO Word64)
-> (CString -> Ptr Word64) -> CString -> IO Word64
forall b c a. (b -> c) -> (a -> b) -> a -> c
. CString -> Ptr Word64
forall a b. Ptr a -> Ptr b
castPtr

uniformRange
  :: (Generator g m, Integral a, Variate a, Integral (Unsigned a),
      Bounded (Unsigned a), Variate (Unsigned a))
  => (a,a) -> g -> m a
uniformRange :: (a, a) -> g -> m a
uniformRange (a
x1,a
x2) g
g
  | Unsigned a
n Unsigned a -> Unsigned a -> Bool
forall a. Eq a => a -> a -> Bool
== Unsigned a
0    = g -> m a
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g   -- Abuse overflow in unsigned types
  | Bool
otherwise = m a
loop
  where
    -- Allow ranges where x2<x1
    (a
i, a
j) | a
x1 a -> a -> Bool
forall a. Ord a => a -> a -> Bool
< a
x2   = (a
x1, a
x2)
           | Bool
otherwise = (a
x2, a
x1)
    --
    n :: Unsigned a
n       = Unsigned a
1 Unsigned a -> Unsigned a -> Unsigned a
forall a. Num a => a -> a -> a
+ a -> a -> Unsigned a
forall a.
(Integral a, Integral (Unsigned a)) =>
a -> a -> Unsigned a
sub a
j a
i
    buckets :: Unsigned a
buckets = Unsigned a
forall a. Bounded a => a
maxBound Unsigned a -> Unsigned a -> Unsigned a
forall a. Integral a => a -> a -> a
`div` Unsigned a
n
    maxN :: Unsigned a
maxN    = Unsigned a
buckets Unsigned a -> Unsigned a -> Unsigned a
forall a. Num a => a -> a -> a
* Unsigned a
n
    loop :: m a
loop    = do Unsigned a
x <- g -> m (Unsigned a)
forall a g (m :: * -> *). (Variate a, Generator g m) => g -> m a
uniform g
g
                 if Unsigned a
x Unsigned a -> Unsigned a -> Bool
forall a. Ord a => a -> a -> Bool
< Unsigned a
maxN then a -> m a
forall (m :: * -> *) a. Monad m => a -> m a
return (a -> m a) -> a -> m a
forall a b. (a -> b) -> a -> b
$! a -> Unsigned a -> a
forall a.
(Integral a, Integral (Unsigned a)) =>
a -> Unsigned a -> a
add a
i (Unsigned a
x Unsigned a -> Unsigned a -> Unsigned a
forall a. Integral a => a -> a -> a
`div` Unsigned a
buckets)
                             else m a
loop
{-# INLINE uniformRange #-}

-- Type family for fixed size integrals. For signed data types it's
-- its unsigned couterpart with same size and for unsigned data types
-- it's same type
type family Unsigned a :: *

type instance Unsigned Int8  = Word8
type instance Unsigned Int16 = Word16
type instance Unsigned Int32 = Word32
type instance Unsigned Int64 = Word64

type instance Unsigned Word8  = Word8
type instance Unsigned Word16 = Word16
type instance Unsigned Word32 = Word32
type instance Unsigned Word64 = Word64

-- GHC-7.6 has a bug (#8072) which results in calculation of wrong
-- number of buckets in function `uniformRange'. Consequently uniformR
-- generates values in wrong range.
#if (WORD_SIZE_IN_BITS < 64) && (__GLASGOW_HASKELL__ == 706)
type instance Unsigned Int   = Word32
type instance Unsigned Word  = Word32
#else
type instance Unsigned Int   = Word
type instance Unsigned Word  = Word
#endif