Math.hs


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module Math where

isPrime :: Int -> Bool
isPrime n = (length [ x | x <- [2..(ceiling $ sqrt $ fromIntegral 2)],
                                n `mod` x == 0]) == 0
factors :: Int -> [Int]
factors n = [x | x <- [1..(n `div` 2)], n `mod` x == 0] ++ [n]

intersect' :: [Int] -> [Int] -> [Int]
intersect' a b = [x | x <- a, x `elem` b]