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, 12 insertions, 14 deletions

diff --git a/proofs/refine.ml b/proofs/refine.ml
index 63ae41075..caa6b9fb3 100644
--- a/proofs/refine.ml
+++ b/proofs/refine.ml
@@ -7,7 +7,6 @@
 (************************************************************************)
 
 open Util
-open Sigma.Notations
 open Proofview.Notations
 open Context.Named.Declaration
 
@@ -73,7 +72,6 @@ let add_side_effects env effects =
 let generic_refine ?(unsafe = true) f gl =
   let gl = Proofview.Goal.assume gl in
   let sigma = Proofview.Goal.sigma gl in
-  let sigma = Sigma.to_evar_map sigma in
   let env = Proofview.Goal.env gl in
   let concl = Proofview.Goal.concl gl in
   (** Save the [future_goals] state to restore them after the
@@ -129,19 +127,20 @@ let generic_refine ?(unsafe = true) f gl =
 let lift c =
   Proofview.tclEVARMAP >>= fun sigma ->
   Proofview.V82.wrap_exceptions begin fun () ->
-  let Sigma (c, sigma, _) = c.run (Sigma.Unsafe.of_evar_map sigma) in
-  Proofview.Unsafe.tclEVARS (Sigma.to_evar_map sigma) >>= fun () ->
+  let (sigma, c) = c sigma in
+  Proofview.Unsafe.tclEVARS sigma >>= fun () ->
   Proofview.tclUNIT c
   end
 
-let make_refine_enter ?unsafe f =
-  { enter = fun gl -> generic_refine ?unsafe (lift f) gl }
+let make_refine_enter ?unsafe f gl = generic_refine ?unsafe (lift f) gl
 
 let refine_one ?(unsafe = true) f =
   Proofview.Goal.enter_one (make_refine_enter ~unsafe f)
 
 let refine ?(unsafe = true) f =
-  let f = { run = fun sigma -> let Sigma (c,sigma,p) = f.run sigma in Sigma (((),c),sigma,p) } in
+  let f evd =
+    let (evd,c) = f evd in (evd,((), c))
+  in
   Proofview.Goal.enter (make_refine_enter ~unsafe f)
 
 (** Useful definitions *)
@@ -154,17 +153,16 @@ let with_type env evd c t =
   in
   evd , j'.Environ.uj_val
 
-let refine_casted ?unsafe f = Proofview.Goal.enter { enter = begin fun gl ->
+let refine_casted ?unsafe f = Proofview.Goal.enter begin fun gl ->
   let gl = Proofview.Goal.assume gl in
   let concl = Proofview.Goal.concl gl in
   let env = Proofview.Goal.env gl in
-  let f = { run = fun h ->
-    let Sigma (c, h, p) = f.run h in
-    let sigma, c = with_type env (Sigma.to_evar_map h) c concl in
-    Sigma (c, Sigma.Unsafe.of_evar_map sigma, p)
-  } in
+  let f h =
+    let (h, c) = f h in
+    with_type env h c concl
+  in
   refine ?unsafe f
-end }
+end
 
 (** {7 solve_constraints}