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, 3 insertions, 1 deletions

diff --git a/plugins/derive/derive.ml b/plugins/derive/derive.ml
index a47dc5b2f..5d1551106 100644
--- a/plugins/derive/derive.ml
+++ b/plugins/derive/derive.ml
@@ -6,6 +6,8 @@
 (*         *       GNU Lesser General Public License Version 2.1        *)
 (************************************************************************)
 
+open Context.Named.Declaration
+
 let map_const_entry_body (f:Term.constr->Term.constr) (x:Safe_typing.private_constants Entries.const_entry_body)
     : Safe_typing.private_constants Entries.const_entry_body =
   Future.chain ~pure:true x begin fun ((b,ctx),fx) ->
@@ -32,7 +34,7 @@ let start_deriving f suchthat lemma =
     let open Proofview in
         TCons ( env , sigma , f_type_type , (fun sigma f_type ->
         TCons ( env , sigma , f_type , (fun sigma ef ->
-        let env' = Environ.push_named (f , (Some ef) , f_type) env in
+        let env' = Environ.push_named (LocalDef (f, ef, f_type)) env in
         let evdref = ref sigma in
         let suchthat = Constrintern.interp_type_evars env' evdref suchthat in
         TCons ( env' , !evdref , suchthat , (fun sigma _ ->