cpp-prelude

← This doesn't mean that everything is all right!

Implement functionality from Haskell's Prelude in C++11. Just for fun. Errors guaranteed.

After playing around with functional immutable lists in C++11, I though it would be nice to have the functionality from Haskell's Prelude (or at least the interesting functions) in C++. This is an attempt to implement some of the functionality on STL containers. Whenever possible, functionality from the STL is used.

Functionality

List operations

• map :: (a -> b) -> [a] -> [b]
• (++) :: [a] -> [a] -> [a] as join
• filter :: (a -> Bool) -> [a] -> [a]
• head :: [a] -> a
• last :: [a] -> a
• tail :: [a] -> [a]
• init :: [a] -> [a]
• null :: [a] -> Bool
• length :: [a] -> Int
• (!!) :: [a] -> Int -> a as at
• reverse :: [a] -> [a]

Reducing lists (folds)

• foldl :: (b -> a -> b) -> b -> [a] -> b
• foldl1 :: (a -> a -> a) -> [a] -> a
• foldr :: (a -> b -> b) -> b -> [a] -> b
• foldr1 :: (a -> a -> a) -> [a] -> a

Special folds

• and :: [Bool] -> Bool
• or :: [Bool] -> Bool
• any :: (a -> Bool) -> [a] -> Bool
• all :: (a -> Bool) -> [a] -> Bool
• sum :: Num a => [a] -> a
• product :: Num a => [a] -> a
• concat :: [[a]] -> [a]
• concatMap :: (a -> [b]) -> [a] -> [b]
• maximum :: Ord a => [a] -> a
• minimum :: Ord a => [a] -> a

Building lists

• scanl :: (b -> a -> b) -> b -> [a] -> [b]
• scanl1 :: (a -> a -> a) -> [a] -> [a]
• scanr :: (a -> b -> b) -> b -> [a] -> [b]
• scanr1 :: (a -> a -> a) -> [a] -> [a]

Infinite lists

Without lazy evaluation, there is not really any way to produce infinite lists. Maybe I'll implement these functions with an additional size parameter.

Sublists

• take :: Int -> [a] -> [a]
• drop :: Int -> [a] -> [a]
• splitAt :: Int -> [a] -> ([a], [a])
• takeWhile :: (a -> Bool) -> [a] -> [a]
• dropWhile :: (a -> Bool) -> [a] -> [a]
• span :: (a -> Bool) -> [a] -> ([a], [a])
• break :: (a -> Bool) -> [a] -> ([a], [a])

Searching lists

• elem :: Eq a => a -> [a] -> Bool
• notElem :: Eq a => a -> [a] -> Bool
• lookup :: Eq a => a -> [(a, b)] -> Maybe b

Zipping and unzipping lists

• zip :: [a] -> [b] -> [(a, b)]
• zip3 :: [a] -> [b] -> [c] -> [(a, b, c)]
• zipWith :: (a -> b -> c) -> [a] -> [b] -> [c]
• zipWith3 :: (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d]
• unzip :: [(a, b)] -> ([a], [b])
• unzip3 :: [(a, b, c)] -> ([a], [b], [c])