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.
---
 engine/evarutil.mli | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

(limited to 'engine/evarutil.mli')

diff --git a/engine/evarutil.mli b/engine/evarutil.mli
index 496ec5bc43..90c5c3dc0d 100644
--- a/engine/evarutil.mli
+++ b/engine/evarutil.mli
@@ -22,18 +22,18 @@ val mk_new_meta : unit -> constr
 
 (** {6 Creating a fresh evar given their type and context} *)
 val new_evar :
-  env -> 'r Sigma.t -> ?src:Evar_kinds.t Loc.located -> ?filter:Filter.t ->
+  env -> evar_map -> ?src:Evar_kinds.t Loc.located -> ?filter:Filter.t ->
   ?candidates:constr list -> ?store:Store.t ->
   ?naming:Misctypes.intro_pattern_naming_expr ->
-  ?principal:bool -> types -> (constr, 'r) Sigma.sigma
+  ?principal:bool -> types -> evar_map * EConstr.t
 
 val new_pure_evar :
-  named_context_val -> 'r Sigma.t -> ?src:Evar_kinds.t Loc.located -> ?filter:Filter.t ->
+  named_context_val -> evar_map -> ?src:Evar_kinds.t Loc.located -> ?filter:Filter.t ->
   ?candidates:constr list -> ?store:Store.t ->
   ?naming:Misctypes.intro_pattern_naming_expr ->
-  ?principal:bool -> types -> (evar, 'r) Sigma.sigma
+  ?principal:bool -> types -> evar_map * evar
 
-val new_pure_evar_full : 'r Sigma.t -> evar_info -> (evar, 'r) Sigma.sigma
+val new_pure_evar_full : evar_map -> evar_info -> evar_map * evar
 
 (** the same with side-effects *)
 val e_new_evar :
@@ -45,23 +45,23 @@ val e_new_evar :
 (** Create a new Type existential variable, as we keep track of 
     them during type-checking and unification. *)
 val new_type_evar :
-  env -> 'r Sigma.t -> ?src:Evar_kinds.t Loc.located -> ?filter:Filter.t ->
+  env -> evar_map -> ?src:Evar_kinds.t Loc.located -> ?filter:Filter.t ->
   ?naming:Misctypes.intro_pattern_naming_expr -> ?principal:bool -> rigid ->
-  (constr * sorts, 'r) Sigma.sigma
+  evar_map * (constr * sorts)
 
 val e_new_type_evar : env -> evar_map ref ->
   ?src:Evar_kinds.t Loc.located -> ?filter:Filter.t ->
   ?naming:Misctypes.intro_pattern_naming_expr -> ?principal:bool -> rigid -> constr * sorts
 
-val new_Type : ?rigid:rigid -> env -> 'r Sigma.t -> (constr, 'r) Sigma.sigma
+val new_Type : ?rigid:rigid -> env -> evar_map -> evar_map * constr
 val e_new_Type : ?rigid:rigid -> env -> evar_map ref -> constr
 
-val restrict_evar : 'r Sigma.t -> existential_key -> Filter.t ->
-  ?src:Evar_kinds.t Loc.located -> constr list option -> (existential_key, 'r) Sigma.sigma
+val restrict_evar : evar_map -> existential_key -> Filter.t ->
+  ?src:Evar_kinds.t Loc.located -> constr list option -> evar_map * existential_key
 
 (** Polymorphic constants *)
 
-val new_global : 'r Sigma.t -> Globnames.global_reference -> (constr, 'r) Sigma.sigma
+val new_global : evar_map -> Globnames.global_reference -> evar_map * constr
 val e_new_global : evar_map ref -> Globnames.global_reference -> constr
 
 (** Create a fresh evar in a context different from its definition context:
@@ -71,11 +71,11 @@ val e_new_global : evar_map ref -> Globnames.global_reference -> constr
    of [inst] are typed in the occurrence context and their type (seen
    as a telescope) is [sign] *)
 val new_evar_instance :
- named_context_val -> 'r Sigma.t -> types -> 
+ named_context_val -> evar_map -> types -> 
   ?src:Evar_kinds.t Loc.located -> ?filter:Filter.t -> ?candidates:constr list ->
   ?store:Store.t -> ?naming:Misctypes.intro_pattern_naming_expr ->
   ?principal:bool ->
-  constr list -> (constr, 'r) Sigma.sigma
+  constr list -> evar_map * constr
 
 val make_pure_subst : evar_info -> 'a array -> (Id.t * 'a) list
 
@@ -133,7 +133,7 @@ val occur_evar_upto : evar_map -> Evar.t -> constr -> bool
 
 (** {6 Value/Type constraints} *)
 
-val judge_of_new_Type : 'r Sigma.t -> (unsafe_judgment, 'r) Sigma.sigma
+val judge_of_new_Type : evar_map -> evar_map * unsafe_judgment
 
 (***********************************************************)
 
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