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bjackson/prime1.hs

Last active January 4, 2017 21:23
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Prime generation
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prime1.hs
isqrt :: Int -> Int
isqrt = floor . sqrt . fromIntegral
genPrime :: Int -> Int
genPrime n =
[x | x <- 2 : [3, 5..], isPrime x] !! (n - 1)
isPrime :: Int -> Bool
isPrime 1 = False
isPrime n =
n == 2 || (odd n && not (any p ([3, 5..isqrt n])))
where p x = n `mod` x == 0
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