val create : init:'b -> f:('b -> 'a -> 'b) -> name:Base.String.t -> ('b -> Sexp.t) -> ('a, 'b) t
val id : ('a, 'b) t -> 'b Type_equal.Id.t
With_fold.Key
val create : init:'b -> f:('b -> 'a -> 'b) -> name:Base.String.t -> ('b -> Sexp.t) -> ('a, 'b) t
val id : ('a, 'b) t -> 'b Type_equal.Id.t