A general method to traverse neighboring elements in lists.

ReferenceSurroundings.hs

-- This module demonstrates two key principles:
--   1. A general method of traversing neighboring elements in lists
--   2. Appropriate and understandable abstractions are always your friends

module ReferenceSurroundings where

-- | Returns sublists from xs of length `size`
--   i.e. chunkIntoSize 3 [1..5] ==
--        [[1, 2, 3], [2, 3, 4], [3, 4, 5]]
chunkInto :: Int -> [b] -> [[b]]
chunkInto size xs
    | size >= length xs = [xs]
    | otherwise = take size xs : chunkInto size  (tail xs)

-- | Example usage
main = do
    -- Adds [1, 2, 3], [2, 3, 4] ... [8, 9, 10]
    print $ map sum $ chunkInto 3 [1..10]

    -- Adds chunks in [1..10] for every chunk size less than 10
    mapM_ (print . sumOfChunks) [1..10]
        where sumOfChunks size = map sum $ chunkInto size [1..10]