let path_string_of t =
let rec aux arity depth = function
| NCic.Appl ((NCic.Meta _|NCic.Implicit _)::_) -> [Variable]
+ | NCic.Appl (NCic.Match _::_) -> [Dead]
| NCic.Appl (NCic.Lambda _ :: _) -> [Variable] (* maybe we should b-reduce *)
| NCic.Appl [] -> assert false
| NCic.Appl l when depth > 10 || List.length l > 50 -> [Variable]