CLEANUP: Context.{Rel,Named}.Declaration.t

  Originally, rel-context was represented as:

    Context.rel_context = Names.Name.t * Constr.t option * Constr.t

  Now it is represented as:

    Context.Rel.t = LocalAssum of Names.Name.t * Constr.t
                  | LocalDef of Names.Name.t * Constr.t * Constr.t

  Originally, named-context was represented as:

    Context.named_context = Names.Id.t * Constr.t option * Constr.t

  Now it is represented as:

    Context.Named.t = LocalAssum of Names.Id.t * Constr.t
                    | LocalDef of Names.Id.t * Constr.t * Constr.t

Motivation:

  (1) In "tactics/hipattern.ml4" file we define "test_strict_disjunction"
      function which looked like this:

        let test_strict_disjunction n lc =
          Array.for_all_i (fun i c ->
            match (prod_assum (snd (decompose_prod_n_assum n c))) with
            | [_,None,c] -> isRel c && Int.equal (destRel c) (n - i)
            | _ -> false) 0 lc

      Suppose that you do not know about rel-context and named-context.
      (that is the case of people who just started to read the source code)
      Merlin would tell you that the type of the value you are destructing
      by "match" is:

        'a * 'b option * Constr.t                    (* worst-case scenario *)

      or

        Named.Name.t * Constr.t option * Constr.t    (* best-case scenario (?) *)

      To me, this is akin to wearing an opaque veil.
      It is hard to figure out the meaning of the values you are looking at.
      In particular, it is hard to discover the connection between the value
      we are destructing above and the datatypes and functions defined
      in the "kernel/context.ml" file.

      In this case, the connection is there, but it is not visible
      (between the function above and the "Context" module).

      ------------------------------------------------------------------------

      Now consider, what happens when the reader see the same function
      presented in the following form:

        let test_strict_disjunction n lc =
          Array.for_all_i (fun i c ->
            match (prod_assum (snd (decompose_prod_n_assum n c))) with
            | [LocalAssum (_,c)] -> isRel c && Int.equal (destRel c) (n - i)
            | _ -> false) 0 lc

      If the reader haven't seen "LocalAssum" before, (s)he can use Merlin
      to jump to the corresponding definition and learn more.

      In this case, the connection is there, and it is directly visible
      (between the function above and the "Context" module).

  (2) Also, if we already have the concepts such as:
      - local declaration
      - local assumption
      - local definition
      and we describe these notions meticulously in the Reference Manual,
      then it is a real pity not to reinforce the connection
      of the actual code with the abstract description we published.

1 files changed, 5 insertions, 3 deletions

diff --git a/proofs/proof_using.ml b/proofs/proof_using.ml
index a69645b116..681a7fa1ad 100644
--- a/proofs/proof_using.ml
+++ b/proofs/proof_using.ml
@@ -10,6 +10,7 @@ open Names
 open Environ
 open Util
 open Vernacexpr
+open Context.Named.Declaration
 
 let to_string e =
   let rec aux = function
@@ -33,7 +34,8 @@ let in_nameset =
 
 let rec close_fwd e s =
   let s' =
-    List.fold_left (fun s (id,b,ty) ->      
+    List.fold_left (fun s decl ->
+      let (id,b,ty) = Context.Named.Declaration.to_tuple decl in
       let vb = Option.(default Id.Set.empty (map (global_vars_set e) b)) in
       let vty = global_vars_set e ty in
       let vbty = Id.Set.union vb vty in
@@ -61,13 +63,13 @@ and set_of_id env ty id =
         Id.Set.union (global_vars_set env ty) acc)
       Id.Set.empty ty
   else if Id.to_string id = "All" then
-    List.fold_right Id.Set.add (List.map pi1 (named_context env)) Id.Set.empty
+    List.fold_right Id.Set.add (List.map get_id (named_context env)) Id.Set.empty
   else if CList.mem_assoc_f Id.equal id !known_names then
     process_expr env (CList.assoc_f Id.equal id !known_names) []
   else Id.Set.singleton id
 
 and full_set env =
-  List.fold_right Id.Set.add (List.map pi1 (named_context env)) Id.Set.empty
+  List.fold_right Id.Set.add (List.map get_id (named_context env)) Id.Set.empty
 
 let process_expr env e ty =
   let ty_expr = SsSingl(Loc.ghost, Id.of_string "Type") in