Main.hs


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{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE TupleSections #-}
module Main where

import System.Environment (getArgs)
import System.Exit (die, exitFailure)

import Parser


main :: IO ()
main = do
    (source, fname) <- getArgs >>= \case
        [] -> (,"<stdin>") <$> getContents
        [fname] -> (,fname) <$> readFile fname
        _ -> die "Usage: hs-visinter [filename.hs]"

    prog <- case parse fname source of
      This errs -> do
          mapM_ (putStrLn . printErrMsg) errs
          exitFailure
      These errs res -> do
          mapM_ (putStrLn . printErrMsg) errs
          return res
      That res -> return res

    print prog