1 files changed, 19 insertions, 8 deletions
diff --git a/src/Haskell/SimpleParser.hs b/src/Haskell/SimpleParser.hs
index 26308de..841e41c 100644
--- a/src/Haskell/SimpleParser.hs
+++ b/src/Haskell/SimpleParser.hs
@@ -22,7 +22,7 @@ pToplevel = TopDef <$> pDef
 
 pDef :: Parser Def
 pDef = do
-    n <- pNameV
+    n <- pVariable
     args <- many pNameV
     symbolO "="
     ex <- pExpr
@@ -34,8 +34,8 @@ pDef = do
 pExpr :: Parser Expr
 pExpr = pLam <|> pCase <|> pApp
   where
-    pSimpleExpr = choice [LitNum <$> pNum
-                         ,Ref <$> (pName <|> try (parens pOperator))
+    pSimpleExpr = choice [Num <$> pNum
+                         ,Ref <$> pVariable
                          ,parens (pExpr `sepBy` symbolO ",") >>= \case
                             [ex] -> return ex
                             exs  -> return $ Tup exs]
@@ -53,10 +53,10 @@ pExpr = pLam <|> pCase <|> pApp
 
     pCase = do
         symbolW "case"
-        n <- pNameV
+        e <- pExpr
         symbolW "of"
         arms <- braces (pCaseArm `sepBy` symbolO ";")
-        return $ Case n arms
+        return $ Case e arms
 
     pCaseArm = do
         pat <- pLargePat
@@ -80,18 +80,26 @@ pNum :: Parser Integer
 pNum = (char '-' >> (negate <$> pPositive)) <|> pPositive
   where pPositive = read <$> many1 digit
 
+pVariable :: Parser Name
+pVariable = pName <|> try (parens pOperator)
+
 pName :: Parser Name
-pName = liftM2 (:) (satisfy isAlpha) pNameRest
+pName = notReserved $ liftM2 (:) (satisfy isAlpha) pNameRest
 
 pNameV :: Parser Name
-pNameV = liftM2 (:) (satisfy isLower) pNameRest
+pNameV = notReserved $ liftM2 (:) (satisfy isLower) pNameRest
 
 pNameT :: Parser Name
-pNameT = liftM2 (:) (satisfy isUpper) pNameRest
+pNameT = notReserved $ liftM2 (:) (satisfy isUpper) pNameRest
 
 pNameRest :: Parser Name
 pNameRest = many (satisfy $ \d -> isAlphaNum d || d == '_') <* aheadW
 
+notReserved :: Parser Name -> Parser Name
+notReserved p =
+    try $ p >>= \n ->
+        if n `elem` reservedWords then unexpected "reserved word" else return n
+
 pOperator :: Parser String
 pOperator = many1 (oneOf ":!#$%&*+./<=>?@\\^|-~") <* aheadO
 
@@ -122,3 +130,6 @@ aheadO = do
 
 whitespace :: Parser ()
 whitespace = void $ many space
+
+reservedWords :: [String]
+reservedWords = ["case", "of", "class", "instance", "where", "let", "in"]