Use reserved bang sym for env result

src/Eval.hs

@@ -17,19 +17,19 @@ evalSingle env term
               "Error: Identifier '" ++ name ++ "' is already defined."
         | otherwise ->
             let res = evalAST env body
-            in Map.insert "__result" res (Map.insert name res env)
+            in Map.insert "!result" res (Map.insert name res env)
   | SApp func arg <- term =
       let res = apply (evalAST env func) (evalAST env arg)
-      in Map.insert "__result" res env
+      in Map.insert "!result" res env
   | SVar name <- term =
       case Map.lookup name env of
         Just v  ->
-          Map.insert "__result" v env
+          Map.insert "!result" v env
         Nothing ->
           errorWithoutStackTrace $ "Variable `" ++ name ++ "` not defined\n\
           \This error should never occur here. Please report this as an issue."
   | otherwise =
-      Map.insert "__result" (evalAST env term) env
+      Map.insert "!result" (evalAST env term) env
 
 evalTricu :: Env -> [TricuAST] -> Env
 evalTricu env x = go env (reorderDefs env x)
@@ -37,7 +37,7 @@ evalTricu env x = go env (reorderDefs env x)
     go env []     = env
     go env [x]    =
       let updatedEnv = evalSingle env x
-      in Map.insert "__result" (result updatedEnv) updatedEnv
+      in Map.insert "!result" (result updatedEnv) updatedEnv
     go env (x:xs) =
       evalTricu (evalSingle env x) xs
 
@@ -180,9 +180,9 @@ depends topDefs (SDef _ _ body) =
 depends _ _ = Set.empty
 
 result :: Env -> T
-result r = case Map.lookup "__result" r of
+result r = case Map.lookup "!result" r of
   Just a -> a
-  Nothing -> errorWithoutStackTrace "No __result field found in provided env"
+  Nothing -> errorWithoutStackTrace "No !result field found in provided env"
 
 mainResult :: Env -> T
 mainResult r = case Map.lookup "main" r of

src/Lexer.hs

@@ -23,8 +23,8 @@ identifier = do
               <|> char '_' <|> char '-' <|> char '?' <|> char '!'
               <|> char '$' <|> char '#' <|> char '@' <|> char '%'
   let name = first : rest
-  if (name == "t" || name == "__result")
+  if (name == "t" || name == "!result")
-    then fail "Keywords (`t`, `__result`) cannot be used as an identifier"
+    then fail "Keywords (`t`, `!result`) cannot be used as an identifier"
     else return (LIdentifier name)
 
 integerLiteral :: Lexer LToken

src/Main.hs

@@ -61,7 +61,7 @@ main = do
       putStrLn "Welcome to the tricu REPL"
       putStrLn "You can exit with `CTRL+D` or the `:_exit` command.`"
       library <- liftIO $ evaluateFile "./lib/base.tri"
-      repl $ Map.delete "__result" library
+      repl $ Map.delete "!result" library
     Evaluate { file = filePaths, form = form } -> do
       result <- case filePaths of
         [] -> do

src/Parser.hs

@@ -244,7 +244,7 @@ parseVarM :: ParserM TricuAST
 parseVarM = do
   satisfyM (\case LIdentifier _ -> True; _ -> False) >>= \case
     LIdentifier name
-      | name == "t" || name == "__result" ->
+      | name == "t" || name == "!result" ->
         fail ("Reserved keyword: " ++ name ++ " cannot be assigned.")
       | otherwise                         ->
          pure (SVar name)

src/REPL.hs

@@ -34,7 +34,7 @@ repl env = runInputT defaultSettings (loop env)
               loop env
             | Just p  <- path -> do
               loadedEnv <- liftIO $ evaluateFileWithContext env (strip p) `catch` \e -> errorHandler env e
-              loop $ Map.delete "__result" (Map.union loadedEnv env)
+              loop $ Map.delete "!result" (Map.union loadedEnv env)
         | Just s <- minput -> do
           if
             | take 2 s == "--" -> loop env
@@ -47,7 +47,7 @@ repl env = runInputT defaultSettings (loop env)
       let asts   = parseTricu input
           newEnv = evalTricu env asts
       if
-        | Just r <- Map.lookup "__result" newEnv -> do
+        | Just r <- Map.lookup "!result" newEnv -> do
           putStrLn $ "tricu > " ++ decodeResult r
         | otherwise -> return ()
       return newEnv

test/Spec.hs

@@ -70,9 +70,9 @@ lexer = testGroup "Lexer Tests"
         Right i -> i @?= expect
 
   , testCase "Error when using invalid characters in identifiers" $ do
-        case (runParser tricuLexer "" "__result = 5") of
+        case (runParser tricuLexer "" "!result = 5") of
           Left _ -> return ()
-          Right _ -> assertFailure "Expected failure when trying to assign the value of __result"
+          Right _ -> assertFailure "Expected failure when trying to assign the value of !result"
   ]
 
 parser :: TestTree