From 48c0636e685f4f9175cde83512220bf52f2737f1 Mon Sep 17 00:00:00 2001
From: kutyel <flaviocorpa@gmail.com>
Date: Sun, 27 Oct 2019 12:34:05 +0100
Subject: [PATCH] All roads lead to traverse!

---
 src/Main.hs  | 41 ++++++++++++++++-------------------------
 src/Morse.hs |  2 +-
 2 files changed, 17 insertions(+), 26 deletions(-)

diff --git a/src/Main.hs b/src/Main.hs
index 136f069..04574d7 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,43 +1,34 @@
 module Main where
 
 import           Control.Monad      (forever, when)
-import           Data.List          (intercalate)
-import           Data.Traversable   (traverse)
 import           Morse              (morseToChar, stringToMorse)
 import           System.Environment (getArgs)
 import           System.Exit        (exitFailure, exitSuccess)
-import           System.IO          (hGetLine, hIsEOF, stdin)
+import           System.IO
+
+convertLine :: (String -> IO ()) -> IO ()
+convertLine convert = do
+  weAreDone <- isEOF
+  when weAreDone exitSuccess
+  -- otherwise, proceed.
+  line <- getLine
+  convert line
 
 convertToMorse :: IO ()
-convertToMorse =
-  forever $ do
-    weAreDone <- hIsEOF stdin
-    when weAreDone exitSuccess
-    -- otherwise, proceed.
-    line <- hGetLine stdin
-    convertLine line
+convertToMorse = forever $ convertLine to
   where
-    convertLine line = do
-      let morse = stringToMorse line
-      case morse of
-        (Just str) -> putStrLn (intercalate " " str)
+    to line =
+      case stringToMorse line of
+        (Just str) -> putStrLn (unwords str)
         Nothing -> do
           putStrLn $ "ERROR: " ++ line
           exitFailure
 
 convertFromMorse :: IO ()
-convertFromMorse =
-  forever $ do
-    weAreDone <- hIsEOF stdin
-    when weAreDone exitSuccess
-    -- otherwise, proceed.
-    line <- hGetLine stdin
-    convertLine line
+convertFromMorse = forever $ convertLine from
   where
-    convertLine line = do
-      let decoded :: Maybe String
-          decoded = traverse morseToChar (words line)
-      case decoded of
+    from line =
+      case traverse morseToChar (words line) of
         (Just s) -> putStrLn s
         Nothing -> do
           putStrLn $ "ERROR: " ++ line
diff --git a/src/Morse.hs b/src/Morse.hs
index 51a9104..6ef1e0e 100644
--- a/src/Morse.hs
+++ b/src/Morse.hs
@@ -59,7 +59,7 @@ charToMorse :: Char -> Maybe Morse
 charToMorse c = M.lookup c letterToMorse
 
 stringToMorse :: String -> Maybe [Morse]
-stringToMorse s = sequence $ fmap charToMorse s
+stringToMorse = traverse charToMorse
 
 morseToChar :: Morse -> Maybe Char
 morseToChar m = M.lookup m morseToLetter