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57 lines
1.2 KiB
57 lines
1.2 KiB
module ReaderPractice where |
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import Control.Applicative |
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import Data.Maybe |
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x :: [Integer] |
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x = [1, 2, 3] |
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y :: [Integer] |
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y = [4, 5, 6] |
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z :: [Integer] |
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z = [7, 8, 9] |
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xs :: Maybe Integer |
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xs = lookup 3 $ zip x y |
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ys :: Maybe Integer |
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ys = lookup 6 $ zip y z |
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zs :: Maybe Integer |
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zs = lookup 4 $ zip x y |
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z' :: Integer -> Maybe Integer |
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z' n = lookup n $ zip x z |
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x1 :: Maybe (Integer, Integer) |
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x1 = liftA2 (,) xs ys |
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x2 :: Maybe (Integer, Integer) |
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x2 = liftA2 (,) ys zs |
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x3 :: Integer -> (Maybe Integer, Maybe Integer) |
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x3 = liftA2 (,) z' z' |
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summed :: Num c => (c, c) -> c |
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summed = uncurry (+) |
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bolt :: Integer -> Bool |
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bolt = liftA2 (&&) (>3) (<8) |
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sequA :: Integral a => a -> [Bool] |
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sequA m = sequenceA [(>3), (<8), even] m |
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s' :: Maybe Integer |
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s' = summed <$> ((,) <$> xs <*> ys) |
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main :: IO () |
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main = do |
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-- print $ sequenceA [Just (3 :: Integer), Just 2, Just 1] |
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-- print $ sequenceA [x, y] |
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-- print $ sequenceA [xs, ys] |
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-- print $ summed <$> ((,) <$> xs <*> ys) |
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-- print $ fmap summed ((,) <$> xs <*> zs) |
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-- print $ bolt 7 |
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-- print $ fmap bolt z |
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print $ and $ sequA (7 :: Integer) |
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print $ sequA $ fromMaybe 0 s' |
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print $ bolt $ fromMaybe 0 ys
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