typing.ml

(**************************************************************************)
(*                                                                        *)
(*  Copyright (C) 2010-2011                                               *)
(*    François Bobot                                                      *)
(*    Jean-Christophe Filliâtre                                           *)
(*    Claude Marché                                                       *)
(*    Andrei Paskevich                                                    *)
(*                                                                        *)
(*  This software is free software; you can redistribute it and/or        *)
(*  modify it under the terms of the GNU Library General Public           *)
(*  License version 2.1, with the special exception on linking            *)
(*  described in file LICENSE.                                            *)
(*                                                                        *)
(*  This software 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.                  *)
(*                                                                        *)
(**************************************************************************)

open Util
open Format
open Pp
open Ident
open Ptree
open Ty
open Term
open Decl
open Theory
open Env
open Denv

(** errors *)

exception DuplicateTypeVar of string
exception TypeArity of qualid * int * int
exception Clash of string
exception PredicateExpected
exception TermExpected
exception FSymExpected of lsymbol
exception PSymExpected of lsymbol
exception BadNumberOfArguments of Ident.ident * int * int
exception ClashTheory of string
exception UnboundTheory of qualid
exception CyclicTypeDef
exception UnboundTypeVar of string
exception UnboundType of string list
exception UnboundSymbol of string list

let error = Loc.error

let errorm = Loc.errorm

let rec print_qualid fmt = function
  | Qident s -> fprintf fmt "%s" s.id
  | Qdot (m, s) -> fprintf fmt "%a.%s" print_qualid m s.id

let () = Exn_printer.register (fun fmt e -> match e with
  | DuplicateTypeVar s ->
      fprintf fmt "duplicate type parameter %s" s
  | TypeArity (id, a, n) ->
      fprintf fmt "@[The type %a expects %d argument(s),@ " print_qualid id a;
      fprintf fmt "but is applied to %d argument(s)@]" n
  | Clash id ->
      fprintf fmt "Clash with previous symbol %s" id
  | PredicateExpected ->
      fprintf fmt "syntax error: predicate expected"
  | TermExpected ->
      fprintf fmt "syntax error: term expected"
  | FSymExpected ls ->
      fprintf fmt "%a is not a function symbol" Pretty.print_ls ls
  | PSymExpected ls ->
      fprintf fmt "%a is not a predicate symbol" Pretty.print_ls ls
  | BadNumberOfArguments (s, n, m) ->
      fprintf fmt "@[Symbol `%s' is applied to %d terms,@ " s.id_string n;
      fprintf fmt "but is expecting %d arguments@]" m
  | ClashTheory s ->
      fprintf fmt "clash with previous theory %s" s
  | UnboundTheory q ->
      fprintf fmt "unbound theory %a" print_qualid q
  | CyclicTypeDef ->
      fprintf fmt "cyclic type definition"
  | UnboundTypeVar s ->
      fprintf fmt "unbound type variable '%s" s
  | UnboundType sl ->
       fprintf fmt "Unbound type '%a'" (print_list dot pp_print_string) sl
  | UnboundSymbol sl ->
       fprintf fmt "Unbound symbol '%a'" (print_list dot pp_print_string) sl
  | _ -> raise e)

let debug_parse_only = Debug.register_stop_flag "parse_only"
let debug_type_only  = Debug.register_stop_flag "type_only"

(** Environments *)

(** typing using destructive type variables

    parsed trees        intermediate trees       typed trees
      (Ptree)               (D below)               (Term)
   -----------------------------------------------------------
     ppure_type  ---dty--->   dty       ---ty--->    ty
      lexpr      --dterm-->   dterm     --term-->    term
      lexpr      --dfmla-->   dfmla     --fmla-->    fmla

*)

let term_expected_type ~loc ty1 ty2 =
  errorm ~loc
    "@[This term has type %a@ but is expected to have type@ %a@]"
    print_dty ty1 print_dty ty2

let unify_raise ~loc ty1 ty2 =
  if not (unify ty1 ty2) then term_expected_type ~loc ty1 ty2

(** Destructive typing environment, that is
    environment + local variables.
    It is only local to this module and created with [create_denv] below. *)

type denv = {
  utyvars : (string, type_var) Hashtbl.t; (* user type variables *)
  dvars   : dty Mstr.t;    (* local variables, to be bound later *)
}

let create_denv () = {
  utyvars = Hashtbl.create 17;
  dvars = Mstr.empty;
}

let create_user_type_var x =
  (* TODO: shouldn't we localize this ident? *)
  let v = create_tvsymbol (id_fresh x) in
  create_ty_decl_var ~user:true v

let find_user_type_var x env =
  try
    Hashtbl.find env.utyvars x
  with Not_found ->
    let v = create_user_type_var x in
    Hashtbl.add env.utyvars x v;
    v

let mem_var x denv = Mstr.mem x denv.dvars
let find_var x denv = Mstr.find x denv.dvars
let add_var x ty denv = { denv with dvars = Mstr.add x ty denv.dvars }

let print_denv fmt denv =
  Mstr.iter (fun x ty -> fprintf fmt "%s:%a,@ " x print_dty ty) denv.dvars

(* parsed types -> intermediate types *)

let rec qloc = function
  | Qident x -> x.id_loc
  | Qdot (m, x) -> Loc.join (qloc m) x.id_loc

let rec string_list_of_qualid acc = function
  | Qident id -> id.id :: acc
  | Qdot (p, id) -> string_list_of_qualid (id.id :: acc) p

let specialize_tysymbol loc p uc =
  let sl = string_list_of_qualid [] p in
  let ts =
    try ns_find_ts (get_namespace uc) sl
    with Not_found -> error ~loc (UnboundType sl)
  in
  ts, List.length ts.ts_args

(* lazy declaration of tuples *)

let add_ty_decl uc dl = add_decl_with_tuples uc (create_ty_decl dl)
let add_logic_decl uc dl = add_decl_with_tuples uc (create_logic_decl dl)
let add_ind_decl uc dl = add_decl_with_tuples uc (create_ind_decl dl)
let add_prop_decl uc k p f = add_decl_with_tuples uc (create_prop_decl k p f)

let rec dty uc env = function
  | PPTtyvar {id=x} ->
      tyvar (find_user_type_var x env)
  | PPTtyapp (p, x) ->
      let loc = qloc x in
      let ts, a = specialize_tysymbol loc x uc in
      let np = List.length p in
      if np <> a then error ~loc (TypeArity (x, a, np));
      let tyl = List.map (dty uc env) p in
      tyapp ts tyl
  | PPTtuple tyl ->
      let ts = ts_tuple (List.length tyl) in
      tyapp ts (List.map (dty uc env) tyl)

let find_ns find p ns =
  let loc = qloc p in
  let sl = string_list_of_qualid [] p in
  try find ns sl
  with Not_found -> error ~loc (UnboundSymbol sl)

let find_prop_ns = find_ns ns_find_pr
let find_prop p uc = find_prop_ns p (get_namespace uc)

let find_tysymbol_ns = find_ns ns_find_ts
let find_tysymbol q uc = find_tysymbol_ns q (get_namespace uc)

let find_lsymbol_ns = find_ns ns_find_ls
let find_lsymbol q uc = find_lsymbol_ns q (get_namespace uc)

let find_fsymbol_ns q ns =
  let ls = find_lsymbol_ns q ns in
  if ls.ls_value = None then error ~loc:(qloc q) (FSymExpected ls) else ls

let find_psymbol_ns q ns =
  let ls = find_lsymbol_ns q ns in
  if ls.ls_value <> None then error ~loc:(qloc q) (PSymExpected ls) else ls

let find_fsymbol q uc = find_fsymbol_ns q (get_namespace uc)
let find_psymbol q uc = find_psymbol_ns q (get_namespace uc)

let find_namespace_ns = find_ns ns_find_ns
let find_namespace q uc = find_namespace_ns q (get_namespace uc)

let specialize_lsymbol p uc =
  let s = find_lsymbol p uc in
  let tl,ty = specialize_lsymbol ~loc:(qloc p) s in
  s,tl,ty

let specialize_fsymbol p uc =
  let s,tl,ty = specialize_lsymbol p uc in
  match ty with
    | None -> let loc = qloc p in error ~loc TermExpected
    | Some ty -> s, tl, ty

let specialize_psymbol p uc =
  let s,tl,ty = specialize_lsymbol p uc in
  match ty with
    | None -> s, tl
    | Some _ -> let loc = qloc p in error ~loc PredicateExpected

let is_psymbol p uc =
  let s = find_lsymbol p uc in
  s.ls_value = None

(* [is_projection uc ls] returns
   - [Some (ts, lsc, i)] if [ls] is the i-th projection of an
     algebraic datatype [ts] with only one constructor [lcs]
   - [None] otherwise
 *)
let is_projection uc ls =
  try
    let ts,tl = match ls.ls_args, ls.ls_value with
      | [{ty_node = Ty.Tyapp (ts, tl)}], Some _ -> ts,tl
      | _ -> (* not a function with 1 argument *) raise Exit
    in
    ignore (List.fold_left (fun tvs t -> match t.ty_node with
      | Ty.Tyvar tv -> Stv.add_new Exit tv tvs
      | _ -> (* not a generic type *) raise Exit) Stv.empty tl);
    let kn = get_known uc in
    let lsc = match Decl.find_constructors kn ts with
      | [lsc] -> lsc
      | _ -> (* 0 or several constructors *) raise Exit
    in
    let def = match Decl.find_logic_definition kn ls with
      | Some def -> def
      | None -> (* no definition *) raise Exit
    in
    let v, t = match Decl.open_ls_defn def with
      | [v], t -> v, t
      | _ -> assert false
    in
    let b = match t.t_node with
      | Tcase ({t_node=Term.Tvar v'}, [b]) when vs_equal v' v -> b
      | _ -> raise Exit
    in
    let p, t = t_open_branch b in
    let pl = match p with
      | { pat_node = Term.Papp (lsc', pl) } when ls_equal lsc lsc' -> pl
      | _ -> raise Exit
    in
    let i = match t.t_node with
      | Term.Tvar xi ->
          let rec index i = function
            | [] -> raise Exit
            | { pat_node = Term.Pvar v} :: _ when vs_equal v xi -> i
            | _ :: l -> index (i+1) l
          in
          index 0 pl
      | _ ->
          raise Exit
    in
    Some (ts, lsc, i)
  with Exit ->
    None

let list_fields uc fl =
  let type_field (q, e) =
    let loc = qloc q in
    let ls = find_lsymbol q uc in
    match is_projection uc ls with
      | None -> errorm ~loc "this is not a record field"
      | Some pr -> pr, loc, e
  in
  let fl = List.map type_field fl in
  let (ts,cs,_),_,_ = List.hd fl in
  let n = List.length cs.ls_args in
  let args = Array.create n None in
  let check_field ((ts',_,i),loc,e) =
    if not (ts_equal ts' ts) then
      errorm ~loc "this should be a field for type %a" Pretty.print_ts ts;
    assert (0 <= i && i < n);
    if args.(i) <> None then
      errorm ~loc "this record field is defined several times";
    args.(i) <- Some (loc,e);
  in
  List.iter check_field fl;
  ts,cs,Array.to_list args


(** Typing types *)

let split_qualid = function
  | Qident id -> [], id.id
  | Qdot (p, id) -> string_list_of_qualid [] p, id.id

(** Typing terms and formulas *)

let binop = function
  | PPand -> Tand
  | PPor -> Tor
  | PPimplies -> Timplies
  | PPiff -> Tiff

let check_pat_linearity p =
  let s = ref Sstr.empty in
  let add id =
    if Sstr.mem id.id !s then
      errorm ~loc:id.id_loc "duplicate variable %s" id.id;
    s := Sstr.add id.id !s
  in
  let rec check p = match p.pat_desc with
    | PPpwild -> ()
    | PPpvar id -> add id
    | PPpapp (_, pl) | PPptuple pl -> List.iter check pl
    | PPprec pfl -> List.iter (fun (_,p) -> check p) pfl
    | PPpas (p, id) -> check p; add id
    | PPpor (p, _) -> check p
  in
  check p

let fresh_type_var loc =
  let tv = create_tvsymbol (id_user "a" loc) in
  tyvar (create_ty_decl_var ~loc ~user:false tv)

let rec dpat uc env pat =
  let env, n, ty = dpat_node pat.pat_loc uc env pat.pat_desc in
  env, { dp_node = n; dp_ty = ty }

and dpat_node loc uc env = function
  | PPpwild ->
      let ty = fresh_type_var loc in
      env, Pwild, ty
  | PPpvar x ->
      let ty = fresh_type_var loc in
      let env = { env with dvars = Mstr.add x.id ty env.dvars } in
      env, Pvar x, ty
  | PPpapp (x, pl) ->
      let s, tyl, ty = specialize_fsymbol x uc in
      let env, pl = dpat_args s.ls_name loc uc env tyl pl in
      env, Papp (s, pl), ty
  | PPprec fl ->
      let renv = ref env in
      let _,cs,fl = list_fields uc fl in
      let tyl,ty = Denv.specialize_lsymbol ~loc cs in
      let al = List.map2 (fun f ty -> match f with
        | Some (_,e) ->
            let loc = e.pat_loc in
            let env,e = dpat uc !renv e in
            unify_raise ~loc e.dp_ty ty;
            renv := env;
            e
        | None -> { dp_node = Pwild; dp_ty = ty }) fl tyl
      in
      !renv, Papp (cs,al), Util.of_option ty
  | PPptuple pl ->
      let n = List.length pl in
      let s = fs_tuple n in
      let tyl = List.map (fun _ -> fresh_type_var loc) pl in
      let env, pl = dpat_args s.ls_name loc uc env tyl pl in
      let ty = tyapp (ts_tuple n) tyl in
      env, Papp (s, pl), ty
  | PPpas (p, x) ->
      let env, p = dpat uc env p in
      let env = { env with dvars = Mstr.add x.id p.dp_ty env.dvars } in
      env, Pas (p,x), p.dp_ty
  | PPpor (p, q) ->
      let env, p = dpat uc env p in
      let env, q = dpat uc env q in
      unify_raise ~loc p.dp_ty q.dp_ty;
      env, Por (p,q), p.dp_ty

and dpat_args s loc uc env el pl =
  let n = List.length el and m = List.length pl in
  if n <> m then error ~loc (BadNumberOfArguments (s, m, n));
  let rec check_arg env = function
    | [], [] ->
        env, []
    | a :: al, p :: pl ->
        let loc = p.pat_loc in
        let env, p = dpat uc env p in
        unify_raise ~loc p.dp_ty a;
        let env, pl = check_arg env (al, pl) in
        env, p :: pl
    | _ ->
        assert false
  in
  check_arg env (el, pl)

let rec trigger_not_a_term_exn = function
  | TermExpected -> true
  | Loc.Located (_, exn) -> trigger_not_a_term_exn exn
  | _ -> false

let check_quant_linearity uqu =
  let s = ref Sstr.empty in
  let check id =
    if Sstr.mem id.id !s then errorm ~loc:id.id_loc "duplicate variable %s" id.id;
    s := Sstr.add id.id !s
  in
  List.iter (fun (idl, _) -> Util.option_iter check idl) uqu

let check_highord uc env x tl = match x with
  | Qident { id = x } when Mstr.mem x env.dvars -> true
  | _ -> List.length tl > List.length ((find_lsymbol x uc).ls_args)

let apply_highord loc x tl = match List.rev tl with
  | a::[] -> [{pp_loc = loc; pp_desc = PPvar x}; a]
  | a::tl -> [{pp_loc = loc; pp_desc = PPapp (x, List.rev tl)}; a]
  | [] -> assert false

let rec dterm ?(localize=None) uc env { pp_loc = loc; pp_desc = t } =
  let n, ty = dterm_node ~localize loc uc env t in
  let t = { dt_node = n; dt_ty = ty } in
  let rec down loc e = match e.dt_node with
    | Tnamed (Lstr _, e) -> down loc e
    | Tnamed (Lpos _, _) -> t
    | _ -> { dt_node = Tnamed (Lpos loc, t); dt_ty = ty }
  in
  match localize with
    | Some (Some loc) -> down loc t
    | Some None -> down loc t
    | None -> t

and dterm_node ~localize loc uc env = function
  | PPvar (Qident {id=x}) when Mstr.mem x env.dvars ->
      (* local variable *)
      let ty = Mstr.find x env.dvars in
      Tvar x, ty
  | PPvar x ->
      (* 0-arity symbol (constant) *)
      let s, tyl, ty = specialize_fsymbol x uc in
      let n = List.length tyl in
      if n > 0 then error ~loc (BadNumberOfArguments (s.ls_name, 0, n));
      Tapp (s, []), ty
  | PPapp (x, tl) when check_highord uc env x tl ->
      let tl = apply_highord loc x tl in
      let atyl, aty = Denv.specialize_lsymbol ~loc fs_func_app in
      let tl = dtype_args ~localize fs_func_app.ls_name loc uc env atyl tl in
      Tapp (fs_func_app, tl), Util.of_option aty
  | PPapp (x, tl) ->
      let s, tyl, ty = specialize_fsymbol x uc in
      let tl = dtype_args ~localize s.ls_name loc uc env tyl tl in
      Tapp (s, tl), ty
  | PPtuple tl ->
      let n = List.length tl in
      let s = fs_tuple n in
      let tyl = List.map (fun _ -> fresh_type_var loc) tl in
      let tl = dtype_args ~localize s.ls_name loc uc env tyl tl in
      let ty = tyapp (ts_tuple n) tyl in
      Tapp (s, tl), ty
  | PPinfix (e1, x, e2) ->
      let s, tyl, ty = specialize_fsymbol (Qident x) uc in
      let tl = dtype_args ~localize s.ls_name loc uc env tyl [e1; e2] in
      Tapp (s, tl), ty
  | PPconst (ConstInt _ as c) ->
      Tconst c, tyapp Ty.ts_int []
  | PPconst (ConstReal _ as c) ->
      Tconst c, tyapp Ty.ts_real []
  | PPlet (x, e1, e2) ->
      let e1 = dterm ~localize uc env e1 in
      let ty = e1.dt_ty in
      let env = { env with dvars = Mstr.add x.id ty env.dvars } in
      let e2 = dterm ~localize uc env e2 in
      Tlet (e1, x, e2), e2.dt_ty
  | PPmatch (e1, bl) ->
      let t1 = dterm ~localize uc env e1 in
      let ty1 = t1.dt_ty in
      let tb = fresh_type_var loc in (* the type of all branches *)
      let branch (p, e) =
        let env, p = dpat_list uc env ty1 p in
        let loc = e.pp_loc in
        let e = dterm ~localize uc env e in
        unify_raise ~loc e.dt_ty tb;
        p, e
      in
      let bl = List.map branch bl in
      Tmatch (t1, bl), tb
  | PPnamed (x, e1) ->
      let localize = match x with
        | Lpos l -> Some (Some l)
        | Lstr _ -> localize
      in
      let e1 = dterm ~localize uc env e1 in
      Tnamed (x, e1), e1.dt_ty
  | PPcast (e1, ty) ->
      let loc = e1.pp_loc in
      let e1 = dterm ~localize uc env e1 in
      let ty = dty uc env ty in
      unify_raise ~loc e1.dt_ty ty;
      e1.dt_node, ty
  | PPif (e1, e2, e3) ->
      let loc = e3.pp_loc in
      let e2 = dterm ~localize uc env e2 in
      let e3 = dterm ~localize uc env e3 in
      unify_raise ~loc e3.dt_ty e2.dt_ty;
      Tif (dfmla ~localize uc env e1, e2, e3), e2.dt_ty
  | PPeps (x, ty, e1) ->
      let ty = dty uc env ty in
      let env = { env with dvars = Mstr.add x.id ty env.dvars } in
      let e1 = dfmla ~localize uc env e1 in
      Teps (x, ty, e1), ty
  | PPquant ((PPlambda|PPfunc|PPpred) as q, uqu, trl, a) ->
      check_quant_linearity uqu;
      let uquant env (idl,ty) =
        let ty = dty uc env ty in
        let id = match idl with
          | Some id -> id
          | None -> assert false
        in
        { env with dvars = Mstr.add id.id ty env.dvars }, (id,ty)
      in
      let env, uqu = map_fold_left uquant env uqu in
      let trigger e =
        try
          TRterm (dterm ~localize uc env e)
        with exn when trigger_not_a_term_exn exn ->
          TRfmla (dfmla ~localize uc env e)
      in
      let trl = List.map (List.map trigger) trl in
      let e = match q with
        | PPfunc -> TRterm (dterm ~localize uc env a)
        | PPpred -> TRfmla (dfmla ~localize uc env a)
        | PPlambda -> trigger a
        | _ -> assert false
      in
      let id, ty, f = match e with
        | TRterm t ->
            let id = { id = "fc"; id_lab = []; id_loc = loc } in
            let tyl,ty = List.fold_right (fun (_,uty) (tyl,ty) ->
              let nty = tyapp ts_func [uty;ty] in ty :: tyl, nty)
              uqu ([],t.dt_ty)
            in
            let h = { dt_node = Tvar id.id ; dt_ty = ty } in
            let h = List.fold_left2 (fun h (uid,uty) ty ->
              let u = { dt_node = Tvar uid.id ; dt_ty = uty } in
              { dt_node = Tapp (fs_func_app, [h;u]) ; dt_ty = ty })
              h uqu tyl
            in
            id, ty, Fapp (ps_equ, [h;t])
        | TRfmla f ->
            let id = { id = "pc"; id_lab = []; id_loc = loc } in
            let (uid,uty),uqu = match List.rev uqu with
              | uq :: uqu -> uq, List.rev uqu
              | [] -> assert false
            in
            let tyl,ty = List.fold_right (fun (_,uty) (tyl,ty) ->
              let nty = tyapp ts_func [uty;ty] in ty :: tyl, nty)
              uqu ([], tyapp ts_pred [uty])
            in
            let h = { dt_node = Tvar id.id ; dt_ty = ty } in
            let h = List.fold_left2 (fun h (uid,uty) ty ->
              let u = { dt_node = Tvar uid.id ; dt_ty = uty } in
              { dt_node = Tapp (fs_func_app, [h;u]) ; dt_ty = ty })
              h uqu tyl
            in
            let u = { dt_node = Tvar uid.id ; dt_ty = uty } in
            id, ty, Fbinop (Tiff, Fapp (ps_pred_app, [h;u]), f)
      in
      Teps (id, ty, Fquant (Tforall, uqu, trl, f)), ty
  | PPrecord fl ->
      let _,cs,fl = list_fields uc fl in
      let tyl,ty = Denv.specialize_lsymbol ~loc cs in
      let al = List.map2 (fun f ty -> match f with
        | Some (_,e) ->
            let loc = e.pp_loc in
            let e = dterm ~localize uc env e in
            unify_raise ~loc e.dt_ty ty;
            e
        | None -> errorm ~loc "some record fields are missing") fl tyl
      in
      Tapp (cs,al), Util.of_option ty
  | PPupdate (e,fl) ->
      let n = ref (-1) in
      let q = Queue.create () in
      let e = dterm ~localize uc env e in
      let _,cs,fl = list_fields uc fl in
      (* prepare the pattern *)
      let tyl,ty = Denv.specialize_lsymbol ~loc cs in
      unify_raise ~loc e.dt_ty (Util.of_option ty);
      let pl = List.map2 (fun f ty -> match f with
        | Some _ ->
            { dp_node = Pwild ; dp_ty = ty }
        | None ->
            let x = (incr n; "x:" ^ string_of_int !n) in
            let i = { id = x ; id_lab = []; id_loc = loc } in
            Queue.add (x,ty) q;
            { dp_node = Pvar i ; dp_ty = ty }) fl tyl
      in
      let p = { dp_node = Papp (cs,pl) ; dp_ty = e.dt_ty } in
      (* prepare the result *)
      let tyl,ty = Denv.specialize_lsymbol ~loc cs in
      let set_pat_var_ty f tyf = match f with
        | Some _ ->
            ()
        | None ->
            let _, xty as v = Queue.take q in
            assert (Denv.unify xty tyf);
            Queue.push v q
      in
      List.iter2 set_pat_var_ty fl tyl;
      let al = List.map2 (fun f ty -> match f with
        | Some (_,e) ->
            let loc = e.pp_loc in
            let e = dterm ~localize uc env e in
            unify_raise ~loc:loc e.dt_ty ty;
            e
        | None ->
            let (x, _) = Queue.take q in
            { dt_node = Tvar x ; dt_ty = ty }) fl tyl
      in
      let t = { dt_node = Tapp (cs,al) ; dt_ty = Util.of_option ty } in
      Tmatch (e,[p,t]), t.dt_ty
  | PPquant _ | PPbinop _ | PPunop _ | PPfalse | PPtrue ->
      error ~loc TermExpected

and dfmla ?(localize=None) uc env { pp_loc = loc; pp_desc = f } =
  let f = dfmla_node ~localize loc uc env f in
  let rec down loc e = match e with
    | Fnamed (Lstr _, e) -> down loc e
    | Fnamed (Lpos _, _) -> f
    | _ -> Fnamed (Lpos loc, f)
  in
  match localize with
    | Some (Some loc) -> down loc f
    | Some None -> down loc f
    | None -> f

and dfmla_node ~localize loc uc env = function
  | PPtrue ->
      Ftrue
  | PPfalse ->
      Ffalse
  | PPunop (PPnot, a) ->
      Fnot (dfmla ~localize uc env a)
  | PPbinop (a, (PPand | PPor | PPimplies | PPiff as op), b) ->
      Fbinop (binop op, dfmla ~localize uc env a, dfmla ~localize uc env b)
  | PPif (a, b, c) ->
      Fif (dfmla ~localize uc env a,
           dfmla ~localize uc env b, dfmla ~localize uc env c)
  | PPquant (q, uqu, trl, a) ->
      check_quant_linearity uqu;
      let uquant env (idl,ty) =
        let ty = dty uc env ty in
        let id = match idl with
          | Some id -> id
          | None -> assert false
        in
        { env with dvars = Mstr.add id.id ty env.dvars }, (id,ty)
      in
      let env, uqu = map_fold_left uquant env uqu in
      let trigger e =
        try
          TRterm (dterm ~localize uc env e)
        with exn when trigger_not_a_term_exn exn ->
          TRfmla (dfmla ~localize uc env e)
      in
      let trl = List.map (List.map trigger) trl in
      let q = match q with
        | PPforall -> Tforall
        | PPexists -> Texists
        | _ -> error ~loc PredicateExpected
      in
      Fquant (q, uqu, trl, dfmla ~localize uc env a)
  | PPapp (x, tl) when check_highord uc env x tl ->
      let tl = apply_highord loc x tl in
      let atyl, _ = Denv.specialize_lsymbol ~loc ps_pred_app in
      let tl = dtype_args ~localize ps_pred_app.ls_name loc uc env atyl tl in
      Fapp (ps_pred_app, tl)
  | PPapp (x, tl) ->
      let s, tyl = specialize_psymbol x uc in
      let tl = dtype_args ~localize s.ls_name loc uc env tyl tl in
      Fapp (s, tl)
  | PPinfix (e12, op2, e3) ->
      begin match e12.pp_desc with
        | PPinfix (_, op1, e2) when is_psymbol (Qident op1) uc ->
            let e23 = { pp_desc = PPinfix (e2, op2, e3); pp_loc = loc } in
            Fbinop (Tand, dfmla ~localize uc env e12,
                    dfmla ~localize uc env e23)
        | _ ->
            let s, tyl = specialize_psymbol (Qident op2) uc in
            let tl = dtype_args ~localize s.ls_name loc uc env tyl [e12;e3] in
            Fapp (s, tl)
      end
  | PPlet (x, e1, e2) ->
      let e1 = dterm ~localize uc env e1 in
      let ty = e1.dt_ty in
      let env = { env with dvars = Mstr.add x.id ty env.dvars } in
      let e2 = dfmla ~localize uc env e2 in
      Flet (e1, x, e2)
  | PPmatch (e1, bl) ->
      let t1 = dterm ~localize uc env e1 in
      let ty1 = t1.dt_ty in
      let branch (p, e) =
        let env, p = dpat_list uc env ty1 p in
        p, dfmla ~localize uc env e
      in
      Fmatch (t1, List.map branch bl)
  | PPnamed (x, f1) ->
      let localize = match x with
        | Lpos l -> Some (Some l)
        | Lstr _ -> localize
      in
      let f1 = dfmla ~localize uc env f1 in
      Fnamed (x, f1)
(*
  | PPvar (Qident s | Qdot (_,s) as x) when is_uppercase s.id.[0] ->
      let pr = find_prop x uc in
      Fvar (Decl.find_prop (Theory.get_known uc) pr)
*)
  | PPvar x ->
      let s, tyl = specialize_psymbol x uc in
      let tl = dtype_args ~localize s.ls_name loc uc env tyl [] in
      Fapp (s, tl)
  | PPeps _ | PPconst _ | PPcast _ | PPtuple _ | PPrecord _ | PPupdate _ ->
      error ~loc PredicateExpected

and dpat_list uc env ty p =
  check_pat_linearity p;
  let loc = p.pat_loc in
  let env, p = dpat uc env p in
  unify_raise ~loc p.dp_ty ty;
  env, p

and dtype_args ~localize s loc uc env el tl =
  let n = List.length el and m = List.length tl in
  if n <> m then error ~loc (BadNumberOfArguments (s, m, n));
  let rec check_arg = function
    | [], [] ->
        []
    | a :: al, t :: bl ->
        let loc = t.pp_loc in
        let t = dterm ~localize uc env t in
        unify_raise ~loc t.dt_ty a;
        t :: check_arg (al, bl)
    | _ ->
        assert false
  in
  check_arg (el, tl)

(** Add projection functions for the algebraic types *)

let add_projection cl p (fs,tyarg,tyval) th =
  let vs = create_vsymbol (id_fresh p) tyval