From 954fbd3b102060ed1e2122f571a430f05a174e42 Mon Sep 17 00:00:00 2001
From: Maxime Dénès
Date: Tue, 9 May 2017 22:14:35 +0200
Subject: 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.
---
 intf/tactypes.mli | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

(limited to 'intf')

diff --git a/intf/tactypes.mli b/intf/tactypes.mli
index ef90b911c5..5c1d31946c 100644
--- a/intf/tactypes.mli
+++ b/intf/tactypes.mli
@@ -22,8 +22,7 @@ open Misctypes
 type glob_constr_and_expr = Glob_term.glob_constr * constr_expr option
 type glob_constr_pattern_and_expr = Id.Set.t * glob_constr_and_expr * constr_pattern
 
-type 'a delayed_open =
-  { delayed : 'r. Environ.env -> 'r Sigma.t -> ('a, 'r) Sigma.sigma }
+type 'a delayed_open = Environ.env -> Evd.evar_map -> Evd.evar_map * 'a
 
 type delayed_open_constr = EConstr.constr delayed_open
 type delayed_open_constr_with_bindings = EConstr.constr with_bindings delayed_open
-- 
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