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diff --git a/ltac/evar_tactics.ml b/ltac/evar_tactics.ml
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+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2016     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+open Util
+open CErrors
+open Evar_refiner
+open Tacmach
+open Tacexpr
+open Refiner
+open Evd
+open Locus
+open Sigma.Notations
+open Proofview.Notations
+open Context.Named.Declaration
+
+(* The instantiate tactic *)
+
+let instantiate_evar evk (ist,rawc) sigma =
+  let evi = Evd.find sigma evk in
+  let filtered = Evd.evar_filtered_env evi in
+  let constrvars = Tacinterp.extract_ltac_constr_values ist filtered in
+  let lvar = {
+    Pretyping.ltac_constrs = constrvars;
+    ltac_uconstrs = Names.Id.Map.empty;
+    ltac_idents = Names.Id.Map.empty;
+    ltac_genargs = ist.Geninterp.lfun;
+  } in
+  let sigma' = w_refine (evk,evi) (lvar ,rawc) sigma in
+  tclEVARS sigma'
+
+let instantiate_tac n c ido =
+  Proofview.V82.tactic begin fun gl ->
+  let sigma = gl.sigma in
+  let evl =
+    match ido with
+	ConclLocation () -> evar_list (pf_concl gl)
+      | HypLocation (id,hloc) ->
+	  let decl = Environ.lookup_named_val id (Goal.V82.hyps sigma (sig_it gl)) in
+	    match hloc with
+		InHyp ->
+		  (match decl with
+                    | LocalAssum (_,typ) -> evar_list typ
+		    | _ -> error
+			"Please be more specific: in type or value?")
+	      | InHypTypeOnly ->
+		  evar_list (get_type decl)
+	      | InHypValueOnly ->
+		  (match decl with
+		    | LocalDef (_,body,_) -> evar_list body
+		    | _ -> error "Not a defined hypothesis.") in
+  if List.length evl < n then
+    error "Not enough uninstantiated existential variables.";
+  if n <= 0 then error "Incorrect existential variable index.";
+  let evk,_ = List.nth evl (n-1) in
+  instantiate_evar evk c sigma gl
+  end
+
+let instantiate_tac_by_name id c =
+  Proofview.V82.tactic begin fun gl ->
+  let sigma = gl.sigma in
+  let evk =
+    try Evd.evar_key id sigma
+    with Not_found -> error "Unknown existential variable." in
+  instantiate_evar evk c sigma gl
+  end
+
+let let_evar name typ =
+  let src = (Loc.ghost,Evar_kinds.GoalEvar) in
+  Proofview.Goal.s_enter { s_enter = begin fun gl ->
+    let sigma = Tacmach.New.project gl in
+    let env = Proofview.Goal.env gl in
+    let sigma = ref sigma in
+    let _ = Typing.e_sort_of env sigma typ in
+    let sigma = Sigma.Unsafe.of_evar_map !sigma in
+    let id = match name with
+    | Names.Anonymous -> 
+      let id = Namegen.id_of_name_using_hdchar env typ name in
+      Namegen.next_ident_away_in_goal id (Termops.ids_of_named_context (Environ.named_context env))
+    | Names.Name id -> id
+    in
+    let Sigma (evar, sigma, p) = Evarutil.new_evar env sigma ~src ~naming:(Misctypes.IntroFresh id) typ in
+    let tac =
+      (Tactics.letin_tac None (Names.Name id) evar None Locusops.nowhere)
+    in
+    Sigma (tac, sigma, p)
+  end }