# Module type Ephemeron.S

    module type S = sig .. end

The output signature of the functor `Ephemeron.K1.Make` and `Ephemeron.K2.Make`. These hash tables are weak in the keys. If all the keys of a binding are alive the binding is kept, but if one of the keys of the binding is dead then the binding is removed.

Propose the same interface as usual hash table. However since the bindings are weak, even if `mem h k` is true, a subsequent `find h k` may raise `Not_found` because the garbage collector can run between the two.

Moreover, the table shouldn't be modified during a call to `iter`. Use `filter_map_inplace` in this case.

    include Hashtbl.S

    val clean : 'a t -> unit

remove all dead bindings. Done automatically during automatic resizing.

    val stats_alive : 'a t -> Hashtbl.statistics

same as `Hashtbl.SeededS.stats` but only count the alive bindings