got it working B)

app/Main.hs

@@ -1,6 +1,12 @@
 module Main where
 
 import Lib
+import Parsing
+import Types
 
 main :: IO ()
-main = someFunc
+main = do
+  content <- fmap (concat . lines) getContents
+  print (stringToHTML content)
+  putStrLn ""
+  print (htmlToString $ stringToHTML content)