Lines: numbering, replacing tabs with arrows

import Data.Text (Text, pack, replace, unpack)
import System.Hclip (setClipboard, getClipboard)
import System.Process (callCommand)
import Text.Regex (Regex, mkRegexWithOpts, subRegex, matchRegex)

tab :: Text
tab = pack "\t"

arrow :: Text
arrow = pack " → "

regex :: Regex
regex = mkRegexWithOpts "^[0-9]+\\. " True False

arrowsWithTabs :: Text -> String
arrowsWithTabs = unpack . replace arrow tab

tabsWithArrows :: Text -> String
tabsWithArrows = unpack . replace tab arrow

lineNumberer :: String -> String
lineNumberer =
  unlines .
  map (\(number, string) -> show number ++ ". " ++ string) . zip [1 ..] . lines

lineDenumberer :: String -> String
lineDenumberer =
  unlines . map (\item -> Text.Regex.subRegex regex item "") . lines

inputCheck :: String -> Maybe [String]
inputCheck = matchRegex regex

dispatcher :: String -> IO ()
dispatcher input
  | inputCheck input == Nothing = do
      setClipboard . lineNumberer . tabsWithArrows $ pack input
      callCommand "espeak -v whisper -a 25 -s 300 'Numbered!'"
  | otherwise = do
      setClipboard . lineDenumberer . arrowsWithTabs $ pack input
      callCommand "espeak -v whisper -a 25 -s 300 'Denumbered!'"

main :: IO ()
main = do
  input <- getClipboard
  dispatcher input