[commit: random] master: Minor: Added a bit of testing related code corresponding to ticket 5278. (ca16c62)

[Ian Lynagh]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/random

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/ca16c628a340107aba04d75757910cecac90c4f3

>---------------------------------------------------------------

commit ca16c628a340107aba04d75757910cecac90c4f3
Author: Ryan Newton <rrnewton at gmail.com>
Date:   Sun Jun 26 22:52:08 2011 -0400

    Minor: Added a bit of testing related code corresponding to ticket 5278.

>---------------------------------------------------------------

 Benchmark/SimpleRNGBench.hs |   20 ++++++++++++++++++--
 System/Random.hs            |    1 +
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/Benchmark/SimpleRNGBench.hs b/Benchmark/SimpleRNGBench.hs
index 2d1bd72..4b4d42d 100644
--- a/Benchmark/SimpleRNGBench.hs
+++ b/Benchmark/SimpleRNGBench.hs
@@ -21,7 +21,7 @@ import Data.IORef
 import Data.Word
 import Data.List hiding (last,sum)
 import Data.Int
-import Data.List.Split
+import Data.List.Split  hiding (split)
 import Text.Printf
 
 import Foreign.Ptr
@@ -80,7 +80,6 @@ measureFreq = do
   return$ fromIntegral (t2 - t1)
 
 ----------------------------------------------------------------------------------------------------
--- Drivers to get random numbers repeatedly.
 
 -- Test overheads without actually generating any random numbers:
 data NoopRNG = NoopRNG
@@ -92,6 +91,23 @@ instance SplittableGen NoopRNG where
 #endif
   split g = (g,g)
 
+-- An RNG generating only 0 or 1:
+data BinRNG = BinRNG StdGen
+instance RandomGen BinRNG where 
+  next (BinRNG g) = (x `mod` 2, BinRNG g')
+    where (x,g') = next g
+#if 1
+  genRange _ = (0,1)
+instance SplittableGen BinRNG where
+#endif
+  split (BinRNG g) = (BinRNG g1, BinRNG g2)
+   where (g1,g2) = split g
+
+mkBinRNG = BinRNG . mkStdGen
+
+----------------------------------------------------------------------------------------------------
+-- Drivers to get random numbers repeatedly.
+
 type Kern = Int -> Ptr Int -> IO ()
 
 -- [2011.01.28] Changing this to take "count" and "accumulator ptr" as arguments:
diff --git a/System/Random.hs b/System/Random.hs
index b36cb28..693566f 100644
--- a/System/Random.hs
+++ b/System/Random.hs
@@ -418,6 +418,7 @@ randomIvalInteger (l,h) rng
 randomFrac :: (RandomGen g, Fractional a) => g -> (a, g)
 randomFrac = randomIvalDouble (0::Double,1) realToFrac
 
+-- BUG: Ticket #5133 - this was found to generate the hi bound for Floats:
 randomIvalFrac :: (RandomGen g, Real a, Fractional b) => (a,a) -> g -> (b, g)
 randomIvalFrac (a,b) = randomIvalDouble (realToFrac a, realToFrac b) realToFrac