From 67967f029305c663fb3fbb4e0f1a6e375f5d572c Mon Sep 17 00:00:00 2001
From: "Juan J. Martinez" <jjm@usebox.net>
Date: Tue, 6 Sep 2022 12:10:57 +0100
Subject: Group variable declaration

---
 src/Parser.hs | 59 +++++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 47 insertions(+), 12 deletions(-)

(limited to 'src/Parser.hs')

diff --git a/src/Parser.hs b/src/Parser.hs
index 2f60b52..2817208 100644
--- a/src/Parser.hs
+++ b/src/Parser.hs
@@ -63,6 +63,7 @@ type' = do
   try typFn
     <|> typ <?> "type"
 
+-- argument
 arg :: Parser (String, Type, Bool, SourcePos)
 arg = do
   pos <- getPosition
@@ -71,6 +72,7 @@ arg = do
   t <- type' <?> "type"
   return $ (i, t, True, pos)
 
+-- function definition (common to def and lambda)
 fdef :: Ident -> Bool -> Bool -> SourcePos -> Parser Expr
 fdef ident priv anon pos = do
   args <- parens $ commaSep arg
@@ -81,8 +83,13 @@ fdef ident priv anon pos = do
           rtyp <- type' <?> "return type"
           return $ rtyp
       )
-  body <- braces $ many statement
-  return $ Func ident args rtyp body priv anon pos
+  body <-
+    braces $
+      many $
+        try (grVar False) <|> do
+          x <- statement
+          pure $ [x]
+  return $ Func ident args rtyp (concat $ body) priv anon pos
 
 function :: Bool -> Parser Expr
 function priv = do
@@ -91,20 +98,42 @@ function priv = do
   ident <- identifier
   fdef ident priv False pos
 
-var :: Bool -> Parser Expr
-var priv = do
-  reserved "var"
+-- ident: type = value
+varWithValue :: Bool -> Parser Expr
+varWithValue priv = do
   (ident, typ, _, pos) <- arg
+  -- FIXME: this error hint is not being used
   reservedOp "=" <?> "assignation"
   value <- expr
-  reservedOp ";"
   return $ Var ident typ value priv pos
 
-privateDfn :: Parser Expr
-privateDfn = do
+-- group variable declaration
+grVar :: Bool -> Parser [Expr]
+grVar priv = do
+  reserved "var"
+  xs <- parens $ commaSep $ varWithValue priv
+  reservedOp ";"
+  return $ xs
+
+-- variable declaration
+var :: Bool -> Parser Expr
+var priv = do
+  reserved "var"
+  x <- varWithValue priv
+  reservedOp ";"
+  return $ x
+
+-- private definition
+privateDf :: (Bool -> Parser Expr) -> Parser Expr
+privateDf f = do
+  priv <- optionMaybe $ reserved "private"
+  f (isJust priv)
+
+-- private group definition
+privateDfn :: (Bool -> Parser [Expr]) -> Parser [Expr]
+privateDfn f = do
   priv <- optionMaybe $ reserved "private"
-  let isPriv = isJust priv
-  try (function isPriv) <|> var isPriv
+  f (isJust priv)
 
 lambdaId :: SourcePos -> Ident
 lambdaId s =
@@ -162,8 +191,14 @@ module' = do
 program :: Parser [Expr]
 program = do
   m <- module'
-  n <- many $ do privateDfn <|> statement
-  return $ [m] ++ n
+  n <-
+    many $
+      try (privateDfn grVar) <|> do
+        x <-
+          try (privateDf function) <|> try (privateDf var)
+            <|> statement
+        pure $ [x]
+  return $ [m] ++ (concat $ n)
 
 parse :: Parser [Expr]
 parse = program
-- 
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