Be much less verbose:

bin/Main.hs

@@ -1,21 +1,49 @@
-{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE LambdaCase      #-}
+{-# LANGUAGE RecordWildCards #-}
 module Main where
 
+import           Data.Maybe
 import           Data.Monoid
-import qualified Data.Text.IO       as Text (hPutStr)
-import           System.Environment (getArgs)
+import qualified Data.Text.IO        as Text (hPutStr)
+import           System.Environment  (getArgs)
 import           System.IO
 
+import           Options.Applicative
 import           Text.JaTex
 
+data Options = Options { optsOutputFile   :: Maybe FilePath
+                       , optsTemplateFile :: Maybe String
+                       , optsInputFile    :: FilePath
+                       }
+
+options :: Parser Options
+options =
+  Options <$>
+  optional
+    (strOption
+       (long "output" <> metavar "OUTPUT_FILE" <> help "LaTeX Output File")) <*>
+  optional
+    (strOption
+       (long "template" <> metavar "TEMPLATE_FILE" <> help "Template File")) <*>
+  argument str (metavar "INPUT_FILE" <> help "XML Input File")
+
+optionsPI :: ParserInfo Options
+optionsPI =
+  info
+    (options <**> helper)
+    (fullDesc <> progDesc "Convert JATS-XML INPUT_FILE to LaTeX OUTPUT_FILE"
+    <> header "jats2tex - Customizable JATS to LaTeX Conversion")
+
 main :: IO ()
-main = getArgs >>= \case
-    [inputFile, outputFile] -> run inputFile =<< openFile outputFile WriteMode
-    [inputFile] -> run inputFile stdout
-    _ -> error "Usage: jatex <input-file> <output-file>"
+main = do
+    Options{..} <- execParser optionsPI
+    outputFile <- case optsOutputFile of
+        Nothing -> return stdout
+        Just f  -> openFile f WriteMode
+    run optsInputFile outputFile
 
 run :: FilePath -> Handle -> IO ()
 run inputFile outputHandle = do
-    hPutStrLn stderr ("Using " <> inputFile <> " writting " <> show outputHandle)
+    -- hPutStrLn stderr ("Using " <> inputFile <> " writting " <> show outputHandle)
     contents <- readJats inputFile
     Text.hPutStr outputHandle (jatsXmlToLaTeXText contents)

examples/simple.xml

@@ -0,0 +1,10 @@
+<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <front>
+    <article-meta>
+      <title-group>
+        <article-title xml:lang="pt"><![CDATA[A influência do genótipo da ECA sobre a aptidão cardiovascular de jovens do sexo masculino moderadamente ativos]]></article-title>
+        <article-title xml:lang="en"><![CDATA[The influence of ACE genotype on cardiovascular fitness of moderately active young men]]></article-title>
+      </title-group>
+    </article-meta>
+  </front>
+</article>

src/Text/JaTex.hs

@@ -35,9 +35,9 @@ runJaTeX = runLaTeXT
 readJats :: FilePath -> IO JATSDoc
 readJats inputFile = do
   inp <- ByteString.readFile inputFile
-  print ICU.converterNames
+  -- print ICU.converterNames
   inp' <- decodeLatin inp
-  print (map fromXMLNode (parseJATS inp') :: [Maybe JATSElement])
+  -- print (map fromXMLNode (parseJATS inp') :: [Maybe JATSElement])
   return $ parseJATS inp'
   where
     decodeLatin i = do