replace m >>= return . f with fmap f m

main.hs

@@ -17,14 +17,15 @@ data ProgArgs = ProgArgs
 	} deriving (Show)
 
 parser :: IO (ParserSpec ProgArgs)
-parser = path >>= \path -> return $ ProgArgs
+parser = (\path -> ProgArgs
   `parsedBy` boolFlag      "interactive" `Descr` "Manually insert numbers"
   `andBy`    optFlag  path "dictionary"  `Descr` "Specify dictionary file path"
   `andBy`    optFlag  6    "lenght"      `Descr` "Number of words in a passphrase"
-  `andBy`    optFlag  1    "phrases"     `Descr` "Number of passphrases to generate"
+  `andBy`    optFlag  1    "phrases"     `Descr` "Number of passphrases to generate")
+  <$> path
 
 interface :: IO (CmdLnInterface ProgArgs)
-interface = 
+interface =
   (`setAppDescr` "A diceware passphrase generator") <$>
   (`setAppEpilog` "Alea iacta est.") <$>
   (mkApp =<< parser)
@@ -39,7 +40,7 @@ path = getDataFileName "dict/diceware"
 -- Read dictionary file
 readDict :: ProgArgs -> IO ProgArgs
 readDict args@ProgArgs{..} =
-  readFile dictionary >>= \x -> return args {dictionary = x}
+  (\x -> args {dictionary = x}) <$> readFile dictionary
 
 -- Main function
 exec :: ProgArgs -> IO ()
@@ -47,8 +48,8 @@ exec args@ProgArgs{..} =
 	if interactive
 	  then interact (unlines . map dice . lines)
 	  else do
-			  randWords dictSize phraseLength >>= putStrLn . unwords . map dice'
-			  when (phrases > 1) $ exec args {phrases = phrases - 1}
+	    randWords dictSize phraseLength >>= putStrLn . unwords . map dice'
+	    when (phrases > 1) $ exec args {phrases = phrases - 1}
 	where
 	  (dict, dictSize) = (parseDiceware dictionary, length dict)
 	  dice  n = readDiceware  dict (read n :: Int)