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Created Aug 8, 2018
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Split the given string up based on a max length, breaking at spaces
splitBy :: (a -> Bool) -> [a] -> [[a]]
splitBy p = map reverse . reverse . splitByInner [[]] p
splitByInner :: [[a]] -> (a -> Bool) -> [a] -> [[a]]
splitByInner acc _ [] = acc
splitByInner (current:rest) predicate (x:xs) =
if predicate x then
splitByInner ([]:current:rest) predicate xs
splitByInner ((x:current):rest) predicate xs
text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
divideIntoGroups :: Foldable t => Int -> [t a] -> [[t a]]
divideIntoGroups n = map reverse . reverse . divideIntoGroupsInner [[]] n
divideIntoGroupsInner :: Foldable t => [[t a]] -> Int -> [t a] -> [[t a]]
divideIntoGroupsInner acc _ [] = acc
divideIntoGroupsInner (current:rest) n (x:xs) =
if newLength > n then
divideIntoGroupsInner ([x]:current:rest) n xs
divideIntoGroupsInner ((x:current):rest) n xs
where newLength = sum (map length current) + length x + length current
joinWith :: a -> [[a]] -> [a]
joinWith _ [] = []
joinWith _ (x:[]) = x
joinWith c (x:xs) = x ++ c:(joinWith c xs)
splitByWords :: Int -> String -> [String]
splitByWords maxChars =
map (joinWith separator)
. divideIntoGroups maxChars
. splitBy (==separator)
where separator = ' '
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