2 files changed, 40 insertions, 1 deletions
diff --git a/src/Language/SimpleShell/Parser.hs b/src/Language/SimpleShell/Parser.hs
index d75602b..be16c9f 100644
--- a/src/Language/SimpleShell/Parser.hs
+++ b/src/Language/SimpleShell/Parser.hs
@@ -4,6 +4,7 @@ module Language.SimpleShell.Parser
   ( Parser
   , lexeme
   , symbol
+  , commentFirstChars
   , lookupVar
   , lookupFun
   , declareVars
@@ -50,12 +51,17 @@ initContext = Context
   }
 
 
+-- Must be kept in sync with 'commentFirstChars'.
 sc :: Parser ()
 sc = L.space
   space1
   (L.skipLineComment "//")
   (L.skipBlockComment "/*" "*/")
 
+-- | List of all characters that may start a comment.
+commentFirstChars :: [Char]
+commentFirstChars = "/"
+
 lexeme :: Parser a -> Parser a
 lexeme = L.lexeme sc
 
diff --git a/src/Language/SimpleShell/Parser/Expr.hs b/src/Language/SimpleShell/Parser/Expr.hs
index 1c782bc..cabf522 100644
--- a/src/Language/SimpleShell/Parser/Expr.hs
+++ b/src/Language/SimpleShell/Parser/Expr.hs
@@ -4,6 +4,7 @@
 module Language.SimpleShell.Parser.Expr
   ( exprP
   , strongTermP
+  , strongTermP_  -- TODO: Unused.
   )
 where
 
@@ -14,6 +15,7 @@ import Language.SimpleShell.Parser
   ( Parser
   , lexeme
   , symbol
+  , commentFirstChars
   , lookupVar
   , lookupFun
   )
@@ -26,9 +28,11 @@ import Control.Monad.Combinators.FailExpr
   )
 
 import Control.Applicative ((<|>))
+import Control.Monad (void)
 import Control.Monad.Combinators (manyTill)
 import Data.Foldable (asum)
 import Data.Text (Text)
+import Text.Megaparsec (takeWhile1P, oneOf, many)
 import Text.Megaparsec.Char (char)
 import qualified Text.Megaparsec.Char.Lexer as L (charLiteral, decimal)
 
@@ -50,6 +54,30 @@ strongTermP
   <|> varP
   <|> symbol "(" *> exprP <* symbol ")"
 
+-- | Parse a strong term--assuming its correctness--without yielding a result.
+--   This basically only checks for matching parentheses.
+strongTermP_ :: Parser ()
+strongTermP_
+   =  void literalP
+  <|> varP_
+  <|> symbol "(" *> void (many tok) <* symbol ")"
+  where
+    -- Notes:
+    --  * We need to make sure to correctly handle:
+    --    * parentheses
+    --    * string literals
+    --    * comments
+
+    tok :: Parser ()
+    tok
+       =  void strLitP
+      <|> symbol "(" *> void (many tok) <* symbol ")"
+      <|> void (lexeme $ takeWhile1P Nothing isBoring)
+      <|> void (lexeme $ oneOf commentFirstChars)
+      where
+        isBoring :: Char -> Bool
+        isBoring = not . (`elem` "()\"" ++ commentFirstChars)
+
 
 -- | Parse "strong" term with fixed type.
 strongTermP' :: String -> SimpleType -> Parser Expr
@@ -62,11 +90,13 @@ literalP
   <|> (StrType,)  . StrLiteral  <$> strLitP
   <|> (BoolType,) . BoolLiteral <$> boolLitP
   where
-    strLitP = lexeme $ char '"' *> manyTill L.charLiteral (char '"')
     boolLitP
        =  True  <$ keyword "true"
       <|> False <$ keyword "false"
 
+strLitP :: Parser String
+strLitP = lexeme $ char '"' *> manyTill L.charLiteral (char '"')
+
 varP :: Parser TypedExpr
 varP = do
   _ <- char '$'
@@ -74,6 +104,9 @@ varP = do
   t <- lookupVar x
   return (t, Var x)
 
+varP_ :: Parser ()
+varP_ = void (char '$') <* nameP
+
 funP :: Parser TypedExpr
 funP = do
   fname <- nameP