From bc620adb5a07d791c67c42abd29d30e5c1a5c4d2 Mon Sep 17 00:00:00 2001
From: Einhard Leichtfuß <alguien@respiranto.de>
Date: Wed, 21 May 2025 12:40:11 +0200
Subject: Distinguish first-pass expression parser

---
 src/Language/SimpleShell/Parser/Expr.hs     | 22 ++++++++++++----------
 src/Language/SimpleShell/Parser/Function.hs |  4 ++--
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/Language/SimpleShell/Parser/Expr.hs b/src/Language/SimpleShell/Parser/Expr.hs
index 672bb05..441e890 100644
--- a/src/Language/SimpleShell/Parser/Expr.hs
+++ b/src/Language/SimpleShell/Parser/Expr.hs
@@ -1,12 +1,13 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE TupleSections #-}
+{-# LANGUAGE FlexibleContexts #-}
 
 module Language.SimpleShell.Parser.Expr
   ( ExprParser
   , runExprParser
   , exprP
   , strongTermP
-  , strongTermP_
+  , strongTermP0_
   )
 where
 
@@ -38,11 +39,12 @@ import Data.Map (Map)
 import qualified Data.Map as Map (empty, lookup, fromList)
 import Data.Text (Text, unpack)
 import Data.Tuple (swap)
-import Text.Megaparsec (takeWhile1P, oneOf, many)
+import Text.Megaparsec (MonadParsec, takeWhile1P, oneOf, many)
 import Text.Megaparsec.Char (char)
 import qualified Text.Megaparsec.Char.Lexer as L (charLiteral, decimal)
 
 
+type ExprParser0 = RootParser
 type ExprParser = ReaderT ExprContext RootParser
 
 
@@ -96,10 +98,10 @@ strongTermP
 
 -- | Parse a strong term--assuming its correctness--without yielding a result.
 --   This basically only checks for matching parentheses.
-strongTermP_ :: ExprParser ()
-strongTermP_
+strongTermP0_ :: ExprParser0 ()
+strongTermP0_
    =  void literalP
-  <|> varP_
+  <|> varP0_
   <|> symbol "(" *> void (many tok) <* symbol ")"
   where
     -- Notes:
@@ -108,7 +110,7 @@ strongTermP_
     --    * string literals
     --    * comments
 
-    tok :: ExprParser ()
+    tok :: ExprParser0 ()
     tok
        =  void strLitP
       <|> symbol "(" *> void (many tok) <* symbol ")"
@@ -124,7 +126,7 @@ strongTermP' :: String -> SimpleType -> ExprParser Expr
 strongTermP' errMsg t = forceType t strongTermP <|> fail errMsg
 
 
-literalP :: ExprParser TypedExpr
+literalP :: (MonadParsec e Text m) => m TypedExpr
 literalP
    =  (IntType,)  . IntLiteral  <$> lexeme L.decimal
   <|> (StrType,)  . StrLiteral  <$> strLitP
@@ -134,7 +136,7 @@ literalP
        =  True  <$ keyword "true"
       <|> False <$ keyword "false"
 
-strLitP :: ExprParser String
+strLitP :: (MonadParsec e Text m) => m String
 strLitP = lexeme $ char '"' *> manyTill L.charLiteral (char '"')
 
 varP :: ExprParser TypedExpr
@@ -144,8 +146,8 @@ varP = do
   t <- lookupVar x
   return (t, Var x)
 
-varP_ :: ExprParser ()
-varP_ = void (char '$') <* nameP
+varP0_ :: ExprParser0 ()
+varP0_ = void (char '$') <* nameP
 
 funP :: ExprParser TypedExpr
 funP = do
diff --git a/src/Language/SimpleShell/Parser/Function.hs b/src/Language/SimpleShell/Parser/Function.hs
index 3565966..be3f424 100644
--- a/src/Language/SimpleShell/Parser/Function.hs
+++ b/src/Language/SimpleShell/Parser/Function.hs
@@ -16,7 +16,7 @@ import Language.SimpleShell.Parser.Common.Root (RootParser)
 import Language.SimpleShell.Parser.Expr
   ( runExprParser
   , strongTermP
-  , strongTermP_
+  , strongTermP0_
   )
 import Language.SimpleShell.Parser.Name (nameP, keyword)
 import Language.SimpleShell.Parser.SimpleType (simpleTypeP, forceType)
@@ -57,4 +57,4 @@ bodyP :: [Typed VarName] -> RootParser (Typed Expr)
 bodyP params = runExprParser params strongTermP
 
 bodyP_ :: RootParser ()
-bodyP_ = runExprParser [] strongTermP_
+bodyP_ = strongTermP0_
-- 
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