2014-10-14 18:09:58 +02:00
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module Alea.Random where
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2014-10-13 21:26:55 +02:00
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import System.Random
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2014-10-14 18:09:58 +02:00
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import Alea.List
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2014-10-13 21:26:55 +02:00
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-- Get n random numbers from the list ys
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randPick :: (Eq a, RandomGen g) => [a] -> Int -> g -> ([a], g)
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randPick [] _ gen = ([], gen)
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randPick _ 0 gen = ([], gen)
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randPick ys n gen = (x : xs', gen'')
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where
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(randIndex, gen') = randomR (0, length ys - 1) gen
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(x, xs) = removeAt randIndex ys
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(xs', gen'') = randPick xs (n-1) gen'
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-- Generate k random number in the range [0, n)
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randWords :: Int -> Int -> IO [Int]
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randWords n k = getStdRandom (randPick [0..n] k)
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