Names.DirPathType of directory paths. Essentially a list of module identifiers. The order is reversed to improve sharing. E.g. A.B.C is "C";"B";"A"
val hash : t -> intHash over directory paths.
val make : module_ident list -> tCreate a directory path. (The list must be reversed).
val repr : t -> module_ident listRepresent a directory path. (The result list is reversed).
val empty : tThe empty directory path.
val is_empty : t -> boolTest whether a directory path is empty.
val dummy : tUsed in Safe_typing.empty_environment and similar
val to_string : t -> stringPrint non-empty directory paths as "root.module.submodule"