REPL import warning; version info in CLI

Adds the ability to toggle result decoding in REPL. Adds several more
useful functions to the base library.

src/REPL.hs

@@ -6,55 +6,69 @@ import Lexer
 import Parser
 import Research
 
-import Control.Exception         (SomeException, catch)
-import Control.Monad.IO.Class    (liftIO)
-import Control.Monad.Catch (handle, MonadCatch)
-import Data.Char                 (isSpace)
-import Data.List                 (dropWhile, dropWhileEnd, intercalate)
+import Control.Exception      (SomeException, catch)
+import Control.Monad.IO.Class (liftIO)
+import Control.Monad.Catch    (handle, MonadCatch)
+import Data.Char              (isSpace)
+import Data.List              ( dropWhile
+                              , dropWhileEnd
+                              , intercalate
+                              , isPrefixOf)
 import System.Console.Haskeline
 
 import qualified Data.Map as Map
 
 repl :: Env -> IO ()
-repl env = runInputT defaultSettings (withInterrupt (loop env))
+repl env = runInputT defaultSettings (withInterrupt (loop env True))
   where
-    loop :: Env -> InputT IO ()
-    loop env = handle (interruptHandler env) $ do
+    loop :: Env -> Bool -> InputT IO ()
+    loop env decode = handle (interruptHandler env decode) $ do
       minput <- getInputLine "tricu < "
       case minput of
         Nothing -> outputStrLn "Exiting tricu"
         Just s
+          | strip s == "" -> loop env decode
           | strip s == "!exit" -> outputStrLn "Exiting tricu"
-          | strip s == "" -> loop env
-          | strip s == "!import" -> do
+          | strip s == "!decode" -> do
+              outputStrLn $ "Decoding " ++ (if decode then "disabled" else "enabled")
+              loop env (not decode)
+          | "!import" `isPrefixOf` strip s -> do
+              let afterImport = dropWhile (== ' ') $ drop (length ("!import" :: String)) (strip s)
+              if not (null afterImport)
+                then outputStrLn "Warning: REPL imports are interactive; \
+                                  \additional arguments are ignored."
+                else pure ()
               path <- getInputLine "File path to load < "
               case path of
                 Nothing -> do
                   outputStrLn "No input received; stopping import."
-                  loop env
+                  loop env decode
                 Just p -> do
-                  loadedEnv <- liftIO $ evaluateFileWithContext env 
+                  loadedEnv <- liftIO $ evaluateFileWithContext env
                     (strip p) `catch` \e -> errorHandler env e
-                  loop $ Map.delete "!result" (Map.union loadedEnv env)
-          | take 2 s == "--" -> loop env
+                  loop (Map.delete "!result" (Map.union loadedEnv env)) decode
+          | take 2 s == "--" -> loop env decode
           | otherwise -> do
-              newEnv <- liftIO $ processInput env s `catch` errorHandler env
-              loop newEnv
+              newEnv <- liftIO $ processInput env s decode `catch` errorHandler env
+              loop newEnv decode
 
-    interruptHandler :: Env -> Interrupt -> InputT IO ()
-    interruptHandler env _ = do
+    interruptHandler :: Env -> Bool -> Interrupt -> InputT IO ()
+    interruptHandler env decode _ = do
       outputStrLn "Interrupted with CTRL+C\n\
                   \You can use the !exit command or CTRL+D to exit"
-      loop env
+      loop env decode
 
-    processInput :: Env -> String -> IO Env
-    processInput env input = do
+    processInput :: Env -> String -> Bool -> IO Env
+    processInput env input decode = do
       let asts   = parseTricu input
           newEnv = evalTricu env asts
-      if
-        | Just r <- Map.lookup "!result" newEnv -> do
-          putStrLn $ "tricu > " ++ decodeResult r
-        | otherwise -> return ()
+      case Map.lookup "!result" newEnv of
+        Just r -> do
+          putStrLn $ "tricu > " ++ 
+            if decode 
+              then decodeResult r
+              else show r
+        Nothing -> pure ()
       return newEnv
     
     errorHandler :: Env -> SomeException -> IO (Env)