gistfile1.hs

-- Modeled on the behavior of https://github.com/burkhartt/Tim.SentenceParser/blob/master/Tim.SentenceParser/Tim.SentenceParser/SentenceParser.cs

import Char

withoutLastWord :: String -> String
withoutLastWord = unwords . init . words

sentenceBefore :: String -> Int -> String
sentenceBefore "" _  = ""
sentenceBefore _ 0   = ""
sentenceBefore inputString lengthToTake
  | lengthToTake <= 0                             = ""
  | lengthToTake >= length inputString            = inputString
  | isSpace (inputString !! (lengthToTake + 1))   = take lengthToTake inputString
  | otherwise                                     = withoutLastWord . take (lengthToTake + 1) $ inputString