add simple REPL to the driver when no arguments are given
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36
Lamb.hs
36
Lamb.hs
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@ -5,7 +5,9 @@
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import System.Environment (getArgs)
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import System.Environment (getArgs)
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import System.Directory (doesFileExist)
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import System.Directory (doesFileExist)
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import System.FilePath (FilePath, splitExtension)
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import System.FilePath (FilePath, splitExtension)
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import Interp (evalFileV, initIO, Value(UnitV))
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import Control.Monad.IO.Class (liftIO)
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import Parser (parseProgram)
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import Interp (evalFileV, evalProgram, initIO, interpret, InterpState, Value(UnitV))
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-- returns Nothing if all files exist, or Just path for the first one that doesn't
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-- returns Nothing if all files exist, or Just path for the first one that doesn't
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allExist :: [FilePath] -> IO (Maybe FilePath)
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allExist :: [FilePath] -> IO (Maybe FilePath)
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@ -16,11 +18,31 @@ allExist (x:xs) = do
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if exists then allExist xs
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if exists then allExist xs
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else return $ Just x
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else return $ Just x
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repl :: InterpState Value
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repl = do
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liftIO $ putStr ">> "
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line <- liftIO getLine
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case parseProgram line of
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Left err -> do
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liftIO $ putStrLn $ "parse error: " ++ show err
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repl
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Right prg -> do
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ev <- evalProgram prg
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liftIO $ print ev
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repl
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repl' :: IO ()
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repl' = interpret repl >> return ()
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main = do
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main = do
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args <- getArgs
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args <- getArgs
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exist <- allExist args
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case args of
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case exist of
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[] -> -- no arguments, launch REPL
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Just file -> putStrLn $ "error: file " ++ file ++ " doesn't exist"
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initIO >> repl'
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Nothing ->
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_ -> do
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initIO >>
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exist <- allExist args
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mapM_ evalFileV args
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case exist of
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Just file -> putStrLn $ "error: file " ++ file ++ " doesn't exist"
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Nothing ->
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initIO >>
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mapM_ evalFileV args
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