UsefulFunctions.hs

-- ### LIST SPECIFICS ###

-- Replicate any `a` an int number of times
replicate :: int -> a -> [a]

-- Apply binary operator to starting element and list, reduces left to right
foldl :: (b -> a -> b) -> b -> [a] -> b
-- Apply binary operator to starting element and list, reduces right to left
foldr :: (a -> b -> b) -> b -> [a] -> b

-- Maps a list to another list given a mapping
map :: (a -> b) -> [a] -> [b]

-- Filters a list
filter :: (a -> Bool) -> [a] -> [a]

-- Concats two lists (also works on strings)
(++) :: [a] -> [a] -> [a]

-- Concats n lists
concat :: [[a]] -> [a]

-- Zips two list into a list of corresponding pairs
zip :: [a] -> [b] -> [(a,b)]

-- Zips two list into one according to given function
zipWith :: (a -> b -> c) -> [a] -> [b] -> [c]

-- Other (operations that go without saying)
head :: [a] -> a
tail :: [a] -> [a]
last :: [a] -> [a]
reverse :: [a] -> [a]

-- Determines if list is empty
null :: [a] -> Bool

-- Gets element in a list at certain index
(!!) :: [a] -> Int -> a

-- Returns prefix of length of given int
take :: Int -> [a] -> [a]

-- Return suffix after given int
drop :: Int -> [a] -> [a]

-- Find minimum in list
minimum :: Ord a => [a] -> a

-- Finds the index for the sought after element
elemIndex :: Eq a => a -> [a] -> Maybe Int

-- Removes duplicste elements from the list, keeps first occurence
nub :: Eq a => [a] -> [a]

-- ### STRING SPECIFICS ###

-- Breaks up string into words seperated by space
words :: String -> [String]

-- Join words with seperating space
unwords :: [String] -> String

-- Breaks up string into lines
lines :: String -> [String]

-- Joins lines with newline
unlines :: [String] -> String


-- ### FUNCTION SPECIFICS ###

-- Function composition
(.) :: (b -> c) -> (a -> b) -> a -> c

-- application operator: b will be evaluated before being used as paramter for a
($) :: (a -> b) -> a -> b

-- reverse of the application operator
(&) :: a -> (a -> b) -> b


-- ### TUPLE SPECIFICS ###

-- Finds value of b corresponding to given a
lookup :: Eq a => a -> [(a,b)] -> Maybe b

-- Get first element in tuple
fst :: (a,b) -> a

-- Get second element in tuple
snd :: (a,b) -> b

-- Swaps first and second
swap :: (a,b) -> (b,a)


-- #### IO SPECIFICS ####

-- Writes string to std. output device, returns void IO
putStr :: String -> IO ()

-- Adds newline character, returns void IO
putStrLn :: String -> IO ()

-- Takes any showable and prints to std. output device, returns void IO
print :: Show a => a -> IO ()

-- Reads line from std. input device, returns IO containing string
getLine :: IO String

-- Reads line from std. input device, returns generic IO type
readLn :: IO a

-- Takes any showable and converts to String
show :: Show a => a -> String

-- Takes String and convert to any readbale value contained in it
read :: Read a => String -> a

-- Returns unicode value of character
ord :: Char -> Int
-- Returns character of unicode value
chr :: Int -> Char


-- ### MONAD SPECIFIC ###

-- (If-without-else) Takes bool condition and performs given monadic if bool succeeds
when :: Monad m => Bool -> m () -> m ()

-- Extract the value from a Maybe Monad
fromJust :: Maybe a -> a

-- Promotes function application
ap :: Monad m => m (a -> b) -> m a -> m b

-- Replicates a monad type into a monad of list values
replicateM :: Monad m => Int -> m a -> m [a]

-- Zips two lists with a given function into a monad of list values
zipWithM :: Monad m => (a -> b -> m c) -> [a] -> [b] -> m [c]

-- Maps a list with given function into a monad of list values
mapM :: Monad m => (a -> m b) -> [a] -> m [b]