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January 16, 2017 13:29
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Haskell Functions
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--- implementation of useful haskell functions | |
--- http://fi.muny.cz/data/IB015/IB015-neimp-funkcie.pdf | |
myAll :: (a -> Bool) -> [a] -> Bool | |
myAll _ [] = True | |
myAll predicate (x:l) = if not (predicate x) then False else myAll predicate l | |
myAnd :: [Bool] -> Bool | |
myAnd = foldr1 (&&) | |
myAny :: (a -> Bool) -> [a] -> Bool | |
myAny _ [] = False | |
myAny p (x:l) = if p x then True else myAny p l | |
myConcat :: [[a]] -> [a] | |
myConcat = foldl1 (++) | |
myConst :: a -> b -> a | |
myConst x y = x | |
myCurry :: ((a,b) -> c) -> a -> b -> c | |
myCurry f a b = f (a,b) | |
myCycle :: [a] -> [a] | |
myCycle x = x ++ (myCycle x) | |
myDrop :: Int -> [a] -> [a] | |
myDrop 0 l = l | |
myDrop nr (_:l) = myDrop (nr-1) l | |
myDropWhile :: (a -> Bool) -> [a] -> [a] | |
myDropWhile p (x:l) = if p x then myDropWhile p l else (x:l) | |
myElem :: Eq a => a -> [a] -> Bool | |
myElem _ [] = False | |
myElem e (x:l) = if x == e then True else myElem e l | |
myEven :: Integral a => a -> Bool | |
myEven nr = nr `mod` 2 == 0 | |
myFilter :: (a -> Bool) -> [a] -> [a] | |
myFilter predicate list = [index | index <- list, predicate index] | |
myFilter' _ [] = [] | |
myFilter' p (x:l) = if p x then x:(myFilter p l) else (myFilter p l) | |
myFlip :: (a -> b -> c) -> b -> a -> c | |
myFlip f b a = f a b | |
myFoldr :: (a -> b -> b) -> b -> [a] -> b | |
myFoldr _ acc [] = acc | |
myFoldr f acc (x:l) = f x (myFoldr f acc l) | |
myFoldr1 :: (a -> a -> a) -> [a] -> a | |
myFoldr1 f (x:l) = myFoldr f x l | |
myFoldl :: (b -> a -> b) -> b -> [a] -> b | |
myFoldl _ acc [] = acc | |
myFoldl f acc (x:l) = myFoldl f (f acc x) l | |
myFoldl1 :: (a -> a -> a) -> [a] -> a | |
myFoldl1 f (x:l) = myFoldl f x l | |
myFst :: (a,b) -> a | |
myFst (a,b) = a | |
myHead :: [a] -> a | |
myHead [] = error "empty list" | |
myHead (x:s) = x | |
myId :: a -> a | |
myId a = a | |
myInit :: [a] -> [a] | |
myInit [x] = [] | |
myInit (x:l) = x:(myInit l) | |
myIterate :: (a -> a) -> a -> [a] | |
myIterate f a = a : myIterate f (f a) | |
myLast :: [a] -> a | |
myLast [x] = x | |
myLast (_:l) = myLast l | |
myLength :: [a] -> Int | |
myLength [] = 0 | |
myLength (_:l) = 1 + myLength l | |
myMap :: (a->b) -> [a] -> [b] | |
myMap f s = [f n | n <- s] | |
myMap' _ [] = [] | |
myMap' f (x:s) = (f x):(myMap f s) | |
myMax :: Ord a => a -> a -> a | |
myMax a b = if a > b then a else b | |
myMaximum :: Ord a => [a] -> a | |
myMaximum = foldr1 max | |
myMin :: Ord a => a -> a -> a | |
myMin a b = if a < b then a else b | |
myMinimum :: Ord a => [a] -> a | |
myMinimum = foldr1 min | |
myMod :: Integer -> Integer -> Integer | |
myMod a b = if a - b < 0 then a else myMod (a-b) b | |
myNot :: Bool -> Bool | |
myNot True = False | |
myNot False = True | |
myNotElem :: Eq a => a -> [a] -> Bool | |
myNotElem _ [] = True | |
myNotElem a (x:l) = if a == x then False else myNotElem a l | |
myNull :: [a] -> Bool | |
myNull [] = True | |
myNull _ = False | |
myOdd :: Integer -> Bool | |
myOdd x = not (even x) | |
myOr :: [Bool] -> Bool | |
myOr = foldr1 (||) | |
myProduct :: [Integer] -> Integer | |
myProduct = foldr1 (*) | |
myRepeat :: a -> [a] | |
myRepeat x = x:myRepeat x | |
myReplicate :: Int -> a -> [a] | |
myReplicate 0 _ = [] | |
myReplicate times x = x : myReplicate (times-1) x | |
myReverse :: [a] -> [a] | |
myReverse = foldr (\x acc -> acc ++ [x]) [] | |
mySnd :: (a,b) -> b | |
mySnd (a,b) = b | |
mySignum :: Integer -> Integer | |
mySignum 0 = 0 | |
mySignum x = if x < 0 then -1 else 1 | |
mySum :: [Integer] -> Integer | |
mySum = foldr1 (+) | |
myTail :: [a] -> [a] | |
myTail [] = error "empty list" | |
myTail (_:l) = l | |
myTake :: Int -> [a] -> [a] | |
myTake 0 _ = [] | |
myTake nr (x:l) = x : myTake (nr-1) l | |
myTakeWhile :: (a -> Bool) -> [a] -> [a] | |
myTakeWhile _ [] = [] | |
myTakeWhile p (x:l) = if p x then x:myTakeWhile p l else [] | |
myUncurry :: (a -> b -> c) -> (a, b) -> c | |
myUncurry f (a,b) = f a b | |
myUnzip :: [(a,b)] -> ([a], [b]) | |
myUnzip [] = ([], []) | |
myUnzip ((x,y):l) = (x:fst z , y:snd z) where z = myUnzip l | |
myZip :: [a] -> [b] -> [(a,b)] | |
myZip (x:xs) (y:ys) = (x,y):(myZip xs ys) | |
myZip _ _ = [] | |
myZipWith :: (a -> b -> c) -> [a] -> [b] -> [c] | |
myZipWith f (x:xs) (y:ys) = (f x y):(myZipWith f xs ys) | |
myZipWith _ _ _ = [] |
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