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module Test.Framework.Seed where
import Test.Framework.Utilities
import System.Random
import Data.Char
data Seed = FixedSeed Int
| RandomSeed
instance Show Seed where
show RandomSeed = "random"
show (FixedSeed n) = show n
instance Read Seed where
readsPrec prec xs = if map toLower random_prefix == "random"
then [(RandomSeed, rest)]
else map (FixedSeed `onLeft`) (readsPrec prec xs)
where (random_prefix, rest) = splitAt 6 xs
-- | Given a 'Seed', returns a new random number generator based on that seed and the
-- actual numeric seed that was used to build that generator, so it can be recreated.
newSeededStdGen :: Seed -> IO (StdGen, Int)
newSeededStdGen (FixedSeed seed) = return $ (mkStdGen seed, seed)
newSeededStdGen RandomSeed = newStdGenWithKnownSeed
newStdGenWithKnownSeed :: IO (StdGen, Int)
newStdGenWithKnownSeed = do
seed <- randomIO
return (mkStdGen seed, seed)
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