Quick and dirty morse decoder in Haskell

Morse.hs

module Codewars.Kata.DecodeMorse (decodeMorse) where

import Codewars.Kata.DecodeMorse.Preload (morseCodes)

import Data.List.Split (splitOn)
import Data.Map.Strict ((!))

decodeMorse :: String -> String
decodeMorse = unwords . filter (not . null) . map ((>>= (morseCodes!)) . words) . splitOn "   "

MorseDecoder.hs

module Main where

import Data.List.Split (splitOn)
import qualified Data.Map.Strict as M

test :: String
test = ".... . -.--   .--- ..- -.. ."

morseCodes :: M.Map String String -- This is given to us by the exercise
morseCodes = M.fromList [("....", "H"), (".", "E"), ("-.--", "Y"), (".---", "J"), ("..-", "U"), ("-..", "D")]

decodeMorse :: String -> String
decodeMorse = maybe "" unwords . traverse (traverse (`M.lookup` (head <$> morseCodes))) . fmap words . splitOn "   "

MorseWithText.hs

{-# LANGUAGE OverloadedStrings #-}

module Codewars.Kata.DecodeMorse (decodeMorse) where

import Codewars.Kata.DecodeMorse.Preload (morseCodes)

import Data.Map.Strict ((!))
import Data.Text hiding (concatMap, unwords)
import Prelude hiding (words)

decodeMorse :: String -> String
decodeMorse = unwords . fmap (concatMap (morseCodes !) . fmap unpack . words) . splitOn "   " . strip . pack