Create utility function for loading and parsing files

app/MimaAsm/Main.hs

@@ -1,10 +1,9 @@
 module Main where
 
-import qualified Data.Text.IO as T
 import           Options.Applicative
-import           Text.Megaparsec
 
 import           Mima.Assembler.Parser
+import           Mima.IO
 import           Mima.Load
 
 data Settings = Settings
@@ -33,13 +32,10 @@ main = do
   settings <- execParser opts
 
   putStrLn $ "Loading assembly file at " ++ infile settings
-  asm <- T.readFile (infile settings)
+  asm <- parseFile parseState (infile settings)
-
+  case asm of
-  putStrLn "Parsing assembly"
+    Nothing -> pure ()
-  let parsed = parse parseState (infile settings) asm
+    Just (state, _) -> do
-  case parsed of
-    Left errorBundle      -> putStrLn $ errorBundlePretty errorBundle
-    Right (state, _) -> do
       putStrLn "Parsing successful"
       putStrLn $ "Writing result to " ++ outfile settings
       saveStateToFile (outfile settings) state

src/Mima/IO.hs

@@ -0,0 +1,17 @@
+module Mima.IO
+  ( parseFile
+  ) where
+
+import qualified Data.Text.IO as T
+import           Text.Megaparsec
+
+import           Mima.Parser.Common
+
+parseFile :: Parser a -> FilePath -> IO (Maybe a)
+parseFile parser filepath = do
+  content <- T.readFile filepath
+  case parse parser filepath content of
+    Right a           -> pure $ Just a
+    Left errorBundle  -> do
+      putStrLn $ errorBundlePretty errorBundle
+      pure Nothing