]> Hello all, I'm having a bit of difficulty getting the sort of type abstraction I want. I have the following sort of module: module type Alg = sig type t type bin_t = t -> t -> t val add : bin_t val sub : bin_t end which just encapsulates a domain and a few operations that can be performed over values. What I want to do is expose the type "t" but _not_ "bin_t" to the world. The specific reason I want this is so that people can only apply functors like the following: module PairLifter : functor ( A : Alg ) -> functor ( Op : sig val op : A.bin_t end ) -> sig val op : (A.t * A.t) -> (A.t * A.t) -> (A.t * A.t) end with operations explicitly defined in implementations of type Alg. That is, assuming there is an implementation of: module IntAlg : Alg with type t = int then I want: module PairAdd = PairLifter(IntAlg)(struct let op = IntAlg.add end) to work fine, but: module PairAdd = PairLifter(IntAlg)(struct let op = ( + ) end) to fail. It is somewhat crucial for the type "t" to be exposed, however, to simplify passing of constants, etc. Anyway, this is a simplified version of what I'm trying to do, and I fear there might be fundamental problems with my understanding of the type system. So, feel free to hold my hand... Thanks, -Andy ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners