(* Copyright (C) 2000, HELM Team.
 * 
 * This file is part of HELM, an Hypertextual, Electronic
 * Library of Mathematics, developed at the Computer Science
 * Department, University of Bologna, Italy.
 * 
 * HELM is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * HELM is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HELM; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA  02111-1307, USA.
 * 
 * For details, see the HELM World-Wide-Web page,
 * http://cs.unibo.it/helm/.
 *)

(* lift n t                                                              *)
(*  lifts [t] of [n]                                                     *)
(*  [from] default 1, lifts only indexes >= [from]                       *)
(*  NOTE: the opposite function (delift_rels) is defined in CicMetaSubst *)
(*  since it needs to restrict the metavariables in case of failure      *)
val lift : ?from:int -> int -> NCic.term -> NCic.term

(* subst t1 t2                                                          *)
(*  substitutes [t1] for [Rel 1] in [t2]                                *)
(*  if avoid_beta_redexes is true (default: false) no new beta redexes  *)
(*  are generated. WARNING: the substitution can diverge when t2 is not *)
(*  well typed and avoid_beta_redexes is true.                          *)
val subst : ?avoid_beta_redexes:bool -> NCic.term -> NCic.term -> NCic.term

(* psubst [avoid] [delift] [lift_args] [t] [map_arg] [args]              
 *  [avoid] : do not leave newly created beta-redexes, default false
 *  [delift] : perform delifting
 *  [t] : term to fill in
 *  [lift_args] : lift argument after map_arg is applied
 *  [args] : stuff to substitute
 *  [map_arg] : map the argument to obtain a term
 *    the function is ReductionStrategy.from_env_for_unwind when psubst is
 *    used to implement nCicReduction.unwind'                              *)
val psubst : 
  ?avoid_beta_redexes:bool -> bool -> int -> 
  ('a -> NCic.term) -> 'a list -> NCic.term -> 
    NCic.term

(* subst_meta (n, Ctx [t_1 ; ... ; t_n]) t                                  *)
(*  returns the term [t] where [Rel i] is substituted with [t_i] lifted by n *)
(*  [t_i] is lifted as usual when it crosses an abstraction                  *)
(* subst_meta (n, Irl _) t -> lift n t                                        *)
val subst_meta : NCic.local_context -> NCic.term -> NCic.term