here-1.1: src/Data/String/Here/Internal.hs

module Data.String.Here.Internal (trim) where

import Data.Char

trim :: String -> String
trim = trimTail . dropWhile isSpace

trimTail :: String -> String
trimTail "" = ""
trimTail s = take (lastNonBlank s) s
  where lastNonBlank = (+1) . fst . foldl acc (0, 0)
        acc (l, n) c | isSpace c = (l, n + 1)
                     | otherwise = (n, n + 1)