[api] Move `Constrexpr` to the `interp` module.

Continuing the interface cleanup we place `Constrexpr` in the
internalization module, which is the one that eliminates it.

This slims down `pretyping` considerably, including removing the
`Univdecls` module which existed only due to bad dependency ordering
in the first place. Thanks to @ Skyskimmer we also remove a duplicate
`univ_decl` definition among `Misctypes` and `UState`.

This is mostly a proof of concept yet as it depends on quite a few
patches of the tree. For sure some tweaks will be necessary, but it
should be good for review now.

IMO the tree is now in a state where we can could easy eliminate more
than 10 modules without any impact, IMHO this is a net saving API-wise
and would help people to understand the structure of the code better.

1 files changed, 66 insertions, 0 deletions

diff --git a/interp/genredexpr.ml b/interp/genredexpr.ml
new file mode 100644
index 000000000..80697461a
--- /dev/null
+++ b/interp/genredexpr.ml
@@ -0,0 +1,66 @@
+(************************************************************************)
+(*         *   The Coq Proof Assistant / The Coq Development Team       *)
+(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
+(* <O___,, *       (see CREDITS file for the list of authors)           *)
+(*   \VV/  **************************************************************)
+(*    //   *    This file is distributed under the terms of the         *)
+(*         *     GNU Lesser General Public License Version 2.1          *)
+(*         *     (see LICENSE file for the text of the license)         *)
+(************************************************************************)
+
+(** Reduction expressions *)
+
+(** The parsing produces initially a list of [red_atom] *)
+
+type 'a red_atom =
+  | FBeta
+  | FMatch
+  | FFix
+  | FCofix
+  | FZeta
+  | FConst of 'a list
+  | FDeltaBut of 'a list
+
+(** This list of atoms is immediately converted to a [glob_red_flag] *)
+
+type 'a glob_red_flag = {
+  rBeta : bool;
+  rMatch : bool;
+  rFix : bool;
+  rCofix : bool;
+  rZeta : bool;
+  rDelta : bool; (** true = delta all but rConst; false = delta only on rConst*)
+  rConst : 'a list
+}
+
+(** Generic kinds of reductions *)
+
+type ('a,'b,'c) red_expr_gen =
+  | Red of bool
+  | Hnf
+  | Simpl of 'b glob_red_flag*('b,'c) Util.union Locus.with_occurrences option
+  | Cbv of 'b glob_red_flag
+  | Cbn of 'b glob_red_flag
+  | Lazy of 'b glob_red_flag
+  | Unfold of 'b Locus.with_occurrences list
+  | Fold of 'a list
+  | Pattern of 'a Locus.with_occurrences list
+  | ExtraRedExpr of string
+  | CbvVm of ('b,'c) Util.union Locus.with_occurrences option
+  | CbvNative of ('b,'c) Util.union Locus.with_occurrences option
+
+type ('a,'b,'c) may_eval =
+  | ConstrTerm of 'a
+  | ConstrEval of ('a,'b,'c) red_expr_gen * 'a
+  | ConstrContext of Misctypes.lident * 'a
+  | ConstrTypeOf of 'a
+
+open Libnames
+open Constrexpr
+open Misctypes
+
+type r_trm = constr_expr
+type r_pat = constr_pattern_expr
+type r_cst = reference or_by_notation
+
+type raw_red_expr = (r_trm, r_cst, r_pat) red_expr_gen