Remove the Sigma (monotonous state) API.

Reminder of (some of) the reasons for removal:

- Despite the claim in sigma.mli, it does *not* prevent evar
  leaks, something like:

  fun env evd ->
  let (evd',ev) = new_evar env evd in
  (evd,ev)

  will typecheck even with Sigma-like type annotations (with a proof of
  reflexivity)

- The API stayed embryonic. Even typing functions were not ported to
  Sigma.

- Some unsafe combinators (Unsafe.tclEVARS) were replaced with slightly
  less unsafe ones (e.g. s_enter), but those ones were not marked unsafe
  at all (despite still being so).

- There was no good story for higher order functions manipulating evar
  maps. Without higher order, one can most of the time get away with
  reusing the same name for the updated evar map.

- Most of the code doing complex things with evar maps was using unsafe
  casts to sigma. This code should be fixed, but this is an orthogonal
  issue.

Of course, this was showing a nice and elegant use of GADTs, but the
cost/benefit ratio in practice did not seem good.

5 files changed, 9 insertions, 15 deletions

diff --git a/plugins/funind/functional_principles_proofs.ml b/plugins/funind/functional_principles_proofs.ml
index c2f705898f..fd49623986 100644
--- a/plugins/funind/functional_principles_proofs.ml
+++ b/plugins/funind/functional_principles_proofs.ml
@@ -1481,7 +1481,7 @@ let new_prove_with_tcc is_mes acc_inv hrec tcc_hyps eqs : tactic =
 			    tclCOMPLETE(
 				    Eauto.eauto_with_bases
 				      (true,5)
-				      [{ Tacexpr.delayed = fun _ sigma -> Sigma.here (Lazy.force refl_equal) sigma}]
+				      [(fun _ sigma -> (sigma, Lazy.force refl_equal))]
 				      [Hints.Hint_db.empty empty_transparent_state false]
 				  )
 			   )
diff --git a/plugins/funind/functional_principles_types.ml b/plugins/funind/functional_principles_types.ml
index a0eb9e2b27..b8070ff885 100644
--- a/plugins/funind/functional_principles_types.ml
+++ b/plugins/funind/functional_principles_types.ml
@@ -12,7 +12,6 @@ open Context.Rel.Declaration
 open Indfun_common
 open Functional_principles_proofs
 open Misctypes
-open Sigma.Notations
 
 module RelDecl = Context.Rel.Declaration
 
@@ -669,11 +668,9 @@ let build_case_scheme fa =
 	 let ind = first_fun_kn,funs_indexes in
 	   (ind,Univ.Instance.empty)(*FIXME*),prop_sort
   in
-  let sigma = Sigma.Unsafe.of_evar_map sigma in
-  let Sigma (scheme, sigma, _) = 
+  let (sigma, scheme) = 
       Indrec.build_case_analysis_scheme_default env sigma ind sf
   in
-  let sigma = Sigma.to_evar_map sigma in
   let scheme_type = EConstr.Unsafe.to_constr ((Typing.unsafe_type_of env sigma) (EConstr.of_constr scheme)) in
   let sorts =
     (fun (_,_,x) ->
diff --git a/plugins/funind/g_indfun.ml4 b/plugins/funind/g_indfun.ml4
index bd2ac8c67b..d28e0aba0a 100644
--- a/plugins/funind/g_indfun.ml4
+++ b/plugins/funind/g_indfun.ml4
@@ -37,9 +37,10 @@ let pr_fun_ind_using_typed prc prlc _ opt_c =
   match opt_c with
     | None -> mt ()
     | Some b ->
-      let (b, _) = Tactics.run_delayed (Global.env ()) Evd.empty b in
+      let (_, b) = b (Global.env ()) Evd.empty in
       spc () ++ hov 2 (str "using" ++ spc () ++ Miscprint.pr_with_bindings prc prlc b)
 
+
 ARGUMENT EXTEND fun_ind_using
   TYPED AS constr_with_bindings option
   PRINTED BY pr_fun_ind_using_typed
diff --git a/plugins/funind/indfun.ml b/plugins/funind/indfun.ml
index a23c51495c..f1a9758e80 100644
--- a/plugins/funind/indfun.ml
+++ b/plugins/funind/indfun.ml
@@ -11,7 +11,6 @@ open Glob_term
 open Declarations
 open Misctypes
 open Decl_kinds
-open Sigma.Notations
 
 module RelDecl = Context.Rel.Declaration
 
@@ -93,7 +92,7 @@ let functional_induction with_clean c princl pat =
       in
       let encoded_pat_as_patlist =
         List.make (List.length args + List.length c_list - 1) None @ [pat] in
-      List.map2 (fun c pat -> ((None,Tacexpr.ElimOnConstr ({ Tacexpr.delayed = fun env sigma -> Sigma ((c,NoBindings), sigma, Sigma.refl) })),(None,pat),None))
+      List.map2 (fun c pat -> ((None,Tacexpr.ElimOnConstr (fun env sigma -> (sigma,(c,NoBindings)) )),(None,pat),None))
         (args@c_list) encoded_pat_as_patlist
     in
     let princ' = Some (princ,bindings) in
diff --git a/plugins/funind/recdef.ml b/plugins/funind/recdef.ml
index e6f199dbae..ff397d2e92 100644
--- a/plugins/funind/recdef.ml
+++ b/plugins/funind/recdef.ml
@@ -42,7 +42,6 @@ open Auto
 open Eauto
 
 open Indfun_common
-open Sigma.Notations
 open Context.Rel.Declaration
 
 (* Ugly things which should not be here *)
@@ -700,11 +699,9 @@ let mkDestructEq :
     observe_tclTHENLIST (str "mkDestructEq")
      [Proofview.V82.of_tactic (generalize new_hyps);
       (fun g2 ->
-        let changefun patvars = { run = fun sigma ->
-          let redfun = pattern_occs [Locus.AllOccurrencesBut [1], expr] in
-          let Sigma (c, sigma, p) = redfun.Reductionops.e_redfun (pf_env g2) sigma (pf_concl g2) in
-          Sigma (c, sigma, p)
-        } in
+        let changefun patvars sigma =
+          pattern_occs [Locus.AllOccurrencesBut [1], expr] (pf_env g2) sigma (pf_concl g2)
+        in
 	Proofview.V82.of_tactic (change_in_concl None changefun) g2);
       Proofview.V82.of_tactic (simplest_case expr)]), to_revert
 
@@ -1357,7 +1354,7 @@ let open_new_goal build_proof sigma using_lemmas ref_ goal_name (gls_type,decomp
 			  (Proofview.V82.of_tactic e_assumption);
 		      Eauto.eauto_with_bases
 			(true,5)
-			[{ Tacexpr.delayed = fun _ sigma -> Sigma.here (Lazy.force refl_equal) sigma}]
+			[(fun _ sigma -> (sigma, (Lazy.force refl_equal)))]
 			[Hints.Hint_db.empty empty_transparent_state false]
 		      ]
 		    )