ES: parser as-pats

Author: Anabra

grin/src/Grin/ExtendedSyntax/Grin.hs

@@ -26,7 +26,7 @@ instance FoldNames Val where
 instance FoldNames BPat where
   foldNames f = \case
     VarPat v     -> f v
-    AsPat t vs v -> f v <> foldNames (ConstTagNode t vs)
+    AsPat t vs v -> f v <> foldNames f (ConstTagNode t vs)
 
 
 instance FoldNames CPat where

grin/src/Grin/ExtendedSyntax/Parse/AST.hs

@@ -54,8 +54,9 @@ alternative i = Alt <$> try (L.indentGuard sc EQ i *> altPat) <*> (op "@" *> var
 -- and we don't want to parenthesize variables, literals and units.
 bindingPat :: Parser BPat
 bindingPat =
-  try (flip AsPat <$> value <*> (op "@" *> var)) <|>
-  VarPat <$> var
+  VarPat <$> var <|>
+  mkAsPat <$> parens ((,) <$> tag <*> many var) <*> (op "@" *> var)
+  where mkAsPat (tag, fields) var = AsPat tag fields var
 
 
 altPat :: Parser CPat