| C.Prod ("_",s,t) ->
if not toplevel then F.fprintf f "(";
F.fprintf f "@[<hov 1>";
- aux ~toplevel:true ctx s;
+ (match s with
+ | C.Prod ("_",_,_) -> aux ~toplevel:false ctx s
+ | _ -> aux ~toplevel:true ctx s);
F.fprintf f "@;→ ";
aux ~toplevel:true ("_"::ctx) t;
F.fprintf f "@]";