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.

1 files changed, 8 insertions, 8 deletions

diff --git a/tactics/elim.ml b/tactics/elim.ml
index 855cb206fe..13d64b8e3f 100644
--- a/tactics/elim.ml
+++ b/tactics/elim.ml
@@ -77,7 +77,7 @@ let tmphyp_name = Id.of_string "_TmpHyp"
 let up_to_delta = ref false (* true *)
 
 let general_decompose recognizer c =
-  Proofview.Goal.enter { enter = begin fun gl ->
+  Proofview.Goal.enter begin fun gl ->
   let type_of = pf_unsafe_type_of gl in
   let sigma = project gl in
   let typc = type_of c in
@@ -87,7 +87,7 @@ let general_decompose recognizer c =
 	    (ifOnHyp (recognizer sigma) (general_decompose_aux (recognizer sigma))
 	      (fun id -> clear [id])));
        exact_no_check c ]
-  end }
+  end
 
 let head_in indl t gl =
   let env = Proofview.Goal.env gl in
@@ -101,10 +101,10 @@ let head_in indl t gl =
   with Not_found -> false
 
 let decompose_these c l =
-  Proofview.Goal.enter { enter = begin fun gl ->
+  Proofview.Goal.enter begin fun gl ->
   let indl = List.map (fun x -> x, Univ.Instance.empty) l in
   general_decompose (fun sigma (_,t) -> head_in indl t gl) c
-  end }
+  end
 
 let decompose_and c =
   general_decompose
@@ -132,7 +132,7 @@ let induction_trailer abs_i abs_j bargs =
     (tclDO (abs_j - abs_i) intro)
     (onLastHypId
        (fun id ->
-          Proofview.Goal.enter { enter = begin fun gl ->
+          Proofview.Goal.enter begin fun gl ->
 	  let idty = pf_unsafe_type_of gl (mkVar id) in
 	  let fvty = global_vars (pf_env gl) (project gl) idty in
 	  let possible_bring_hyps =
@@ -150,11 +150,11 @@ let induction_trailer abs_i abs_j bargs =
           let ids = List.rev (ids_of_named_context hyps) in
 	  (tclTHENLIST
             [revert ids; simple_elimination (mkVar id)])
-          end }
+          end
           ))
 
 let double_ind h1 h2 =
-  Proofview.Goal.enter { enter = begin fun gl ->
+  Proofview.Goal.enter begin fun gl ->
   let abs_i = depth_of_quantified_hypothesis true h1 gl in
   let abs_j = depth_of_quantified_hypothesis true h2 gl in
   let abs =
@@ -167,7 +167,7 @@ let double_ind h1 h2 =
        	(fun id ->
            elimination_then
              (introElimAssumsThen (induction_trailer abs_i abs_j)) (mkVar id))))
-  end }
+  end
 
 let h_double_induction = double_ind