[sledge] Add List.Assoc support for deriving compare, equal, sexp_of

Reviewed By: ngorogiannis

Differential Revision: D29441157

fbshipit-source-id: cc90ad68b

sledge/nonstdlib/list.ml

@@ -112,6 +112,9 @@ let pp_diff ~cmp ?pre ?suf sep pp_elt fs (xs, ys) =
 module Assoc = struct
   include Assoc
 
+  let compare (type k v) compare_k compare_v = [%compare: (k * v) list]
+  let equal (type k v) equal_k equal_v = [%equal: (k * v) list]
+  let sexp_of_t sexp_of_k sexp_of_v = [%sexp_of: (k * v) list]
   let mem elt seq ~eq = mem ~eq elt seq
 end
 

sledge/nonstdlib/list.mli

@@ -103,7 +103,9 @@ val symmetric_diff :
   cmp:('a -> 'a -> int) -> 'a t -> 'a t -> ('a, 'a) Either.t t
 
 module Assoc : sig
-  include module type of Assoc
+  type ('k, 'v) t = ('k * 'v) list [@@deriving compare, equal, sexp_of]
+
+  include module type of Assoc with type ('k, 'v) t := ('k, 'v) t
 
   val mem : 'a -> ('a, _) t -> eq:('a -> 'a -> bool) -> bool
 end