random 1.0.1.0 → 1.0.1.1

raw patch · 2 files changed

+22/−8 lines, 2 files

Files

• System/Random.hs +17/−6
• random.cabal +5/−2

@@ -6,7 +6,7 @@ -- | -- Module      :  System.Random -- Copyright   :  (c) The University of Glasgow 2001--- License     :  BSD-style (see the file libraries/base/LICENSE)+-- License     :  BSD-style (see the file LICENSE in the 'random' repository) --  -- Maintainer  :  libraries@haskell.org -- Stability   :  stable@@ -114,7 +114,11 @@ -- | The class 'RandomGen' provides a common interface to random number -- generators. --+#ifdef ENABLE_SPLITTABLEGEN -- Minimal complete definition: 'next'.+#else+-- Minimal complete definition: 'next' and 'split'.+#endif  class RandomGen g where @@ -147,7 +151,7 @@  #ifdef ENABLE_SPLITTABLEGEN -- | The class 'SplittableGen' proivides a way to specify a random number--- generator that can be split into two new generators.+--   generator that can be split into two new generators. class SplittableGen g where #endif    -- |The 'split' operation allows one to obtain two distinct random number@@ -355,11 +359,11 @@   random g	  = randomR (minBound,maxBound) g  {-# INLINE randomRFloating #-}-randomRFloating :: (Num a, Ord a, Random a, RandomGen g) => (a, a) -> g -> (a, g)+randomRFloating :: (Fractional a, Num a, Ord a, Random a, RandomGen g) => (a, a) -> g -> (a, g) randomRFloating (l,h) g      | l>h       = randomRFloating (h,l) g     | otherwise = let (coef,g') = random g in -		  (l + coef * (h-l), g')+		  (2.0 * (0.5*l + coef * (0.5*h - 0.5*l)), g')  -- avoid overflow  instance Random Double where   randomR = randomRFloating@@ -423,14 +427,17 @@  | otherwise = case (f n 1 rng) of (v, rng') -> (fromInteger (l + v `mod` k), rng')      where        k = h - l + 1+       -- ERROR: b here (2^31-87) represents a baked-in assumption about genRange:        b = 2147483561        n = iLogBase b k +       -- Here we loop until we've generated enough randomness to cover the range:        f 0 acc g = (acc, g)        f n' acc g =           let 	   (x,g')   = next g 	  in+          -- We shift over the random bits generated thusfar (* b) and add in the new ones. 	  f (n' - 1) (fromIntegral x + acc * b) g'  -- The continuous functions on the other hand take an [inclusive,exclusive) range.@@ -445,8 +452,8 @@          (x, rng') ->  	    let 	     scaled_x = -		fromDouble ((l+h)/2) + -                fromDouble ((h-l) / realToFrac int32Count) *+		fromDouble (0.5*l + 0.5*h) +                   -- previously (l+h)/2, overflowed+                fromDouble ((0.5*h - 0.5*l) / (0.5 * realToFrac int32Count)) *  -- avoid overflow 		fromIntegral (x::Int32) 	    in 	    (scaled_x, rng')@@ -454,6 +461,10 @@ int32Count :: Integer int32Count = toInteger (maxBound::Int32) - toInteger (minBound::Int32) + 1 +-- Perform an expensive logarithm on arbitrary-size integers by repeated division.+-- +-- (NOTE: This actually returns ceiling(log(i) base b) except with an+--  incorrect result at iLogBase b b = 2.) iLogBase :: Integer -> Integer -> Integer iLogBase b i = if i < b then 1 else 1 + iLogBase b (i `div` b) 

@@ -1,7 +1,8 @@ name:		random-version:	1.0.1.0+version:	1.0.1.1  -- 1.0.1.0 -- bump for bug fixes, but no SplittableGen yet+-- 1.0.1.1 -- bump for overflow bug fixes  license:	BSD3 license-file:	LICENSE@@ -10,7 +11,9 @@ synopsis:	random number library category:       System description:-	This package provides a random number library.+	This package provides a basic random number generation+	library, including the ability to split random number+	generators. build-type: Simple Cabal-Version: >= 1.6