- b = binder; vars = LIST1 IDENT SEP SYMBOL ",";
- typ = OPT [ SYMBOL ":"; t = term -> t ];
+ b = binder;
+ (vars, typ) =
+ [ vars = LIST1 IDENT SEP SYMBOL ",";
+ typ = OPT [ SYMBOL ":"; t = term -> t ] -> (vars, typ)
+ | PAREN "("; vars = LIST1 IDENT SEP SYMBOL ",";
+ typ = OPT [ SYMBOL ":"; t = term -> t ]; PAREN ")" -> (vars, typ)
+ ];