path: root/plugins/extraction/ocaml.ml

(************************************************************************)
(*  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        *)
(************************************************************************)

(*s Production of Ocaml syntax. *)

open Pp
open CErrors
open Util
open Names
open Nameops
open Globnames
open Table
open Miniml
open Mlutil
open Modutil
open Common


(*s Some utility functions. *)

let pp_tvar id = str ("'" ^ Id.to_string id)

let pp_abst = function
  | [] -> mt ()
  | l  ->
      str "fun " ++ prlist_with_sep (fun () -> str " ") pr_id l ++
      str " ->" ++ spc ()

let pp_parameters l =
  (pp_boxed_tuple pp_tvar l ++ space_if (not (List.is_empty l)))

let pp_string_parameters l =
  (pp_boxed_tuple str l ++ space_if (not (List.is_empty l)))

let pp_letin pat def body =
  let fstline = str "let " ++ pat ++ str " =" ++ spc () ++ def in
  hv 0 (hv 0 (hov 2 fstline ++ spc () ++ str "in") ++ spc () ++ hov 0 body)

(*s Ocaml renaming issues. *)

let keywords =
  List.fold_right (fun s -> Id.Set.add (Id.of_string s))
  [ "and"; "as"; "assert"; "begin"; "class"; "constraint"; "do";
    "done"; "downto"; "else"; "end"; "exception"; "external"; "false";
    "for"; "fun"; "function"; "functor"; "if"; "in"; "include";
    "inherit"; "initializer"; "lazy"; "let"; "match"; "method";
    "module"; "mutable"; "new"; "object"; "of"; "open"; "or";
    "parser"; "private"; "rec"; "sig"; "struct"; "then"; "to"; "true";
    "try"; "type"; "val"; "virtual"; "when"; "while"; "with"; "mod";
    "land"; "lor"; "lxor"; "lsl"; "lsr"; "asr" ; "unit" ; "_" ; "__" ]
  Id.Set.empty

(* Note: do not shorten [str "foo" ++ fnl ()] into [str "foo\n"],
   the '\n' character interacts badly with the Format boxing mechanism *)

let pp_open mp = str ("open "^ string_of_modfile mp) ++ fnl ()

let pp_comment s = str "(* " ++ hov 0 s ++ str " *)"

let pp_header_comment = function
  | None -> mt ()
  | Some com -> pp_comment com ++ fnl2 ()

let then_nl pp = if Pp.is_empty pp then mt () else pp ++ fnl ()

let pp_tdummy usf =
  if usf.tdummy || usf.tunknown then str "type __ = Obj.t" ++ fnl () else mt ()

let pp_mldummy usf =
  if usf.mldummy then
    str "let __ = let rec f _ = Obj.repr f in Obj.repr f" ++ fnl ()
  else mt ()

let preamble _ comment used_modules usf =
  pp_header_comment comment ++
  then_nl (prlist pp_open used_modules) ++
  then_nl (pp_tdummy usf ++ pp_mldummy usf)

let sig_preamble _ comment used_modules usf =
  pp_header_comment comment ++
  then_nl (prlist pp_open used_modules) ++
  then_nl (pp_tdummy usf)

(*s The pretty-printer for Ocaml syntax*)

(* Beware of the side-effects of [pp_global] and [pp_modname].
   They are used to update table of content for modules. Many [let]
   below should not be altered since they force evaluation order.
*)

let str_global k r =
  if is_inline_custom r then find_custom r else Common.pp_global k r

let pp_global k r = str (str_global k r)

let pp_modname mp = str (Common.pp_module mp)

let is_infix r =
  is_inline_custom r &&
  (let s = find_custom r in
   let l = String.length s in
   l >= 2 && s.[0] == '(' && s.[l-1] == ')')

let get_infix r =
  let s = find_custom r in
  String.sub s 1 (String.length s - 2)

let get_ind = function
  | IndRef _ as r -> r
  | ConstructRef (ind,_) -> IndRef ind
  | _ -> assert false

let pp_one_field r i = function
  | Some r -> pp_global Term r
  | None -> pp_global Type (get_ind r) ++ str "__" ++ int i

let pp_field r fields i = pp_one_field r i (List.nth fields i)

let pp_fields r fields = List.map_i (pp_one_field r) 0 fields

(*s Pretty-printing of types. [par] is a boolean indicating whether parentheses
    are needed or not. *)

let pp_type par vl t =
  let rec pp_rec par = function
    | Tmeta _ | Tvar' _ | Taxiom -> assert false
    | Tvar i -> (try pp_tvar (List.nth vl (pred i))
                 with Failure _ -> (str "'a" ++ int i))
    | Tglob (r,[a1;a2]) when is_infix r ->
	pp_par par (pp_rec true a1 ++ str (get_infix r) ++ pp_rec true a2)
    | Tglob (r,[]) -> pp_global Type r
    | Tglob (IndRef(kn,0),l)
	when not (keep_singleton ()) && MutInd.equal kn (mk_ind "Coq.Init.Specif" "sig") ->
	pp_tuple_light pp_rec l
    | Tglob (r,l) ->
	pp_tuple_light pp_rec l ++ spc () ++ pp_global Type r
    | Tarr (t1,t2) ->
	pp_par par
	  (pp_rec true t1 ++ spc () ++ str "->" ++ spc () ++ pp_rec false t2)
    | Tdummy _ -> str "__"
    | Tunknown -> str "__"
  in
  hov 0 (pp_rec par t)

(*s Pretty-printing of expressions. [par] indicates whether
    parentheses are needed or not. [env] is the list of names for the
    de Bruijn variables. [args] is the list of collected arguments
    (already pretty-printed). *)

let is_bool_patt p s =
  try
    let r = match p with
      | Pusual r -> r
      | Pcons (r,[]) -> r
      | _ -> raise Not_found
    in
    String.equal (find_custom r) s
  with Not_found -> false


let is_ifthenelse = function
  | [|([],p1,_);([],p2,_)|] -> is_bool_patt p1 "true" && is_bool_patt p2 "false"
  | _ -> false

let expr_needs_par = function
  | MLlam _  -> true
  | MLcase (_,_,[|_|]) -> false
  | MLcase (_,_,pv) -> not (is_ifthenelse pv)
  | _        -> false

let rec pp_expr par env args =
  let apply st = pp_apply st par args
  and apply2 st = pp_apply2 st par args in
  function
    | MLrel n ->
	let id = get_db_name n env in
        (* Try to survive to the occurrence of a Dummy rel.
           TODO: we should get rid of this hack (cf. #592) *)
        let id = if Id.equal id dummy_name then Id.of_string "__" else id in
        apply (pr_id id)
    | MLapp (f,args') ->
	let stl = List.map (pp_expr true env []) args' in
        pp_expr par env (stl @ args) f
    | MLlam _ as a ->
      	let fl,a' = collect_lams a in
	let fl = List.map id_of_mlid fl in
	let fl,env' = push_vars fl env in
	let st = pp_abst (List.rev fl) ++ pp_expr false env' [] a' in
	apply2 st
    | MLletin (id,a1,a2) ->
	let i,env' = push_vars [id_of_mlid id] env in
	let pp_id = pr_id (List.hd i)
	and pp_a1 = pp_expr false env [] a1
	and pp_a2 = pp_expr (not par && expr_needs_par a2) env' [] a2 in
	hv 0 (apply2 (pp_letin pp_id pp_a1 pp_a2))
    | MLglob r ->
	(try
	   let args = List.skipn (projection_arity r) args in
	   let record = List.hd args in
	   pp_apply (record ++ str "." ++ pp_global Term r) par (List.tl args)
	 with e when CErrors.noncritical e -> apply (pp_global Term r))
    | MLfix (i,ids,defs) ->
	let ids',env' = push_vars (List.rev (Array.to_list ids)) env in
	pp_fix par env' i (Array.of_list (List.rev ids'),defs) args
    | MLexn s ->
	(* An [MLexn] may be applied, but I don't really care. *)
	pp_par par (str "assert false" ++ spc () ++ str ("(* "^s^" *)"))
    | MLdummy k ->
        (* An [MLdummy] may be applied, but I don't really care. *)
        (match msg_of_implicit k with
         | "" -> str "__"
         | s -> str "__" ++ spc () ++ str ("(* "^s^" *)"))
    | MLmagic a ->
	pp_apply (str "Obj.magic") par (pp_expr true env [] a :: args)
    | MLaxiom ->
	pp_par par (str "failwith \"AXIOM TO BE REALIZED\"")
    | MLcons (_,r,a) as c ->
        assert (List.is_empty args);
        begin match a with
	  | _ when is_native_char c -> pp_native_char c
	  | [a1;a2] when is_infix r ->
	    let pp = pp_expr true env [] in
	    pp_par par (pp a1 ++ str (get_infix r) ++ pp a2)
	  | _ when is_coinductive r ->
	    let ne = not (List.is_empty a) in
	    let tuple = space_if ne ++ pp_tuple (pp_expr true env []) a in
	    pp_par par (str "lazy " ++ pp_par ne (pp_global Cons r ++ tuple))
	  | [] -> pp_global Cons r
	  | _ ->
	    let fds = get_record_fields r in
	    if not (List.is_empty fds) then
	      pp_record_pat (pp_fields r fds, List.map (pp_expr true env []) a)
	    else
	      let tuple = pp_tuple (pp_expr true env []) a in
	      if String.is_empty (str_global Cons r) (* hack Extract Inductive prod *)
	      then tuple
	      else pp_par par (pp_global Cons r ++ spc () ++ tuple)
	end
    | MLtuple l ->
        assert (List.is_empty args);
        pp_boxed_tuple (pp_expr true env []) l
    | MLcase (_, t, pv) when is_custom_match pv ->
        if not (is_regular_match pv) then
	  error "Cannot mix yet user-given match and general patterns.";
	let mkfun (ids,_,e) =
	  if not (List.is_empty ids) then named_lams (List.rev ids) e
	  else dummy_lams (ast_lift 1 e) 1
	in
	let pp_branch tr = pp_expr true env [] (mkfun tr) ++ fnl () in
	let inner =
	  str (find_custom_match pv) ++ fnl () ++
	  prvect pp_branch pv ++
	  pp_expr true env [] t
	in
	apply2 (hov 2 inner)
    | MLcase (typ, t, pv) ->
        let head =
	  if not (is_coinductive_type typ) then pp_expr false env [] t
	  else (str "Lazy.force" ++ spc () ++ pp_expr true env [] t)
	in
	(* First, can this match be printed as a mere record projection ? *)
        (try pp_record_proj par env typ t pv args
	 with Impossible ->
	   (* Second, can this match be printed as a let-in ? *)
	   if Int.equal (Array.length pv) 1 then
	     let s1,s2 = pp_one_pat env pv.(0) in
	     hv 0 (apply2 (pp_letin s1 head s2))
	   else
	     (* Third, can this match be printed as [if ... then ... else] ? *)
	     (try apply2 (pp_ifthenelse env head pv)
	      with Not_found ->
		(* Otherwise, standard match *)
		apply2
		  (v 0 (str "match " ++ head ++ str " with" ++ fnl () ++
			pp_pat env pv))))

and pp_record_proj par env typ t pv args =
  (* Can a match be printed as a mere record projection ? *)
  let fields = record_fields_of_type typ in
  if List.is_empty fields then raise Impossible;
  if not (Int.equal (Array.length pv) 1) then raise Impossible;
  if has_deep_pattern pv then raise Impossible;
  let (ids,pat,body) = pv.(0) in
  let n = List.length ids in
  let no_patvar a = not (List.exists (ast_occurs_itvl 1 n) a) in
  let rel_i,a = match body with
    | MLrel i when i <= n -> i,[]
    | MLapp(MLrel i, a) when i<=n && no_patvar a -> i,a
    | _ -> raise Impossible
  in
  let rec lookup_rel i idx = function
    | Prel j :: l -> if Int.equal i j then idx else lookup_rel i (idx+1) l
    | Pwild :: l -> lookup_rel i (idx+1) l
    | _ -> raise Impossible
  in
  let r,idx = match pat with
    | Pusual r -> r, n-rel_i
    | Pcons (r,l) -> r, lookup_rel rel_i 0 l
    | _ -> raise Impossible
  in
  if is_infix r then raise Impossible;
  let env' = snd (push_vars (List.rev_map id_of_mlid ids) env) in
  let pp_args = (List.map (pp_expr true env' []) a) @ args in
  let pp_head = pp_expr true env [] t ++ str "." ++ pp_field r fields idx
  in
  pp_apply pp_head par pp_args

and pp_record_pat (fields, args) =
   str "{ " ++
   prlist_with_sep (fun () -> str ";" ++ spc ())
     (fun (f,a) -> f ++ str " =" ++ spc () ++ a)
     (List.combine fields args) ++
   str " }"

and pp_cons_pat r ppl =
  if is_infix r && Int.equal (List.length ppl) 2 then
    List.hd ppl ++ str (get_infix r) ++ List.hd (List.tl ppl)
  else
    let fields = get_record_fields r in
    if not (List.is_empty fields) then pp_record_pat (pp_fields r fields, ppl)
    else if String.is_empty (str_global Cons r) then
      pp_boxed_tuple identity ppl (* Hack Extract Inductive prod *)
    else
      pp_global Cons r ++ space_if (not (List.is_empty ppl)) ++ pp_boxed_tuple identity ppl

and pp_gen_pat ids env = function
  | Pcons (r, l) -> pp_cons_pat r (List.map (pp_gen_pat ids env) l)
  | Pusual r -> pp_cons_pat r (List.map pr_id ids)
  | Ptuple l -> pp_boxed_tuple (pp_gen_pat ids env) l
  | Pwild -> str "_"
  | Prel n -> pr_id (get_db_name n env)

and pp_ifthenelse env expr pv = match pv with
  | [|([],tru,the);([],fal,els)|] when
      (is_bool_patt tru "true") && (is_bool_patt fal "false")
      ->
      hv 0 (hov 2 (str "if " ++ expr) ++ spc () ++
            hov 2 (str "then " ++
		   hov 2 (pp_expr (expr_needs_par the) env [] the)) ++ spc () ++
	    hov 2 (str "else " ++
	           hov 2 (pp_expr (expr_needs_par els) env [] els)))
  | _ -> raise Not_found

and pp_one_pat env (ids,p,t) =
  let ids',env' = push_vars (List.rev_map id_of_mlid ids) env in
  pp_gen_pat (List.rev ids') env' p,
  pp_expr (expr_needs_par t) env' [] t

and pp_pat env pv =
  prvecti
    (fun i x ->
       let s1,s2 = pp_one_pat env x in
       hv 2 (hov 4 (str "| " ++ s1 ++ str " ->") ++ spc () ++ hov 2 s2) ++
       if Int.equal i (Array.length pv - 1) then mt () else fnl ())
    pv

and pp_function env t =
  let bl,t' = collect_lams t in
  let bl,env' = push_vars (List.map id_of_mlid bl) env in
  match t' with
    | MLcase(Tglob(r,_),MLrel 1,pv) when
	not (is_coinductive r) && List.is_empty (get_record_fields r) &&
	not (is_custom_match pv) ->
	if not (ast_occurs 1 (MLcase(Tunknown,MLaxiom,pv))) then
	  pr_binding (List.rev (List.tl bl)) ++
       	  str " = function" ++ fnl () ++
	  v 0 (pp_pat env' pv)
	else
          pr_binding (List.rev bl) ++
          str " = match " ++ pr_id (List.hd bl) ++ str " with" ++ fnl () ++
	  v 0 (pp_pat env' pv)
    | _ ->
          pr_binding (List.rev bl) ++
	  str " =" ++ fnl () ++ str "  " ++
	  hov 2 (pp_expr false env' [] t')

(*s names of the functions ([ids]) are already pushed in [env],
    and passed here just for convenience. *)

and pp_fix par env i (ids,bl) args =
  pp_par par
    (v 0 (str "let rec " ++
	  prvect_with_sep
      	    (fun () -> fnl () ++ str "and ")
	    (fun (fi,ti) -> pr_id fi ++ pp_function env ti)
	    (Array.map2 (fun id b -> (id,b)) ids bl) ++
	  fnl () ++
	  hov 2 (str "in " ++ pp_apply (pr_id ids.(i)) false args)))

(* Ad-hoc double-newline in v boxes, with enough negative whitespace
   to avoid indenting the intermediate blank line *)

let cut2 () = brk (0,-100000) ++ brk (0,0)

let pp_val e typ =
  hov 4 (str "(** val " ++ e ++ str " :" ++ spc () ++ pp_type false [] typ ++
  str " **)")  ++ cut2 ()

(*s Pretty-printing of [Dfix] *)

let pp_Dfix (rv,c,t) =
  let names = Array.map
    (fun r -> if is_inline_custom r then mt () else pp_global Term r) rv
  in
  let rec pp init i =
    if i >= Array.length rv then mt ()
    else
      let void = is_inline_custom rv.(i) ||
	(not (is_custom rv.(i)) &&
         match c.(i) with MLexn "UNUSED" -> true | _ -> false)
      in
      if void then pp init (i+1)
      else
	let def =
	  if is_custom rv.(i) then str " = " ++ str (find_custom rv.(i))
	  else pp_function (empty_env ()) c.(i)
	in
	(if init then mt () else cut2 ()) ++
	pp_val names.(i) t.(i) ++
	str (if init then "let rec " else "and ") ++ names.(i) ++ def ++
	pp false (i+1)
  in pp true 0

(*s Pretty-printing of inductive types declaration. *)

let pp_equiv param_list name = function
  | NoEquiv, _ -> mt ()
  | Equiv kn, i ->
      str " = " ++ pp_parameters param_list ++ pp_global Type (IndRef (mind_of_kn kn,i))
  | RenEquiv ren, _  ->
      str " = " ++ pp_parameters param_list ++ str (ren^".") ++ name


let pp_one_ind prefix ip_equiv pl name cnames ctyps =
  let pl = rename_tvars keywords pl in
  let pp_constructor i typs =
    (if Int.equal i 0 then mt () else fnl ()) ++
    hov 3 (str "| " ++ cnames.(i) ++
	   (if List.is_empty typs then mt () else str " of ") ++
	   prlist_with_sep
	    (fun () -> spc () ++ str "* ") (pp_type true pl) typs)
  in
  pp_parameters pl ++ str prefix ++ name ++
  pp_equiv pl name ip_equiv ++ str " =" ++
  if Int.equal (Array.length ctyps) 0 then str " unit (* empty inductive *)"
  else fnl () ++ v 0 (prvecti pp_constructor ctyps)

let pp_logical_ind packet =
  pp_comment (pr_id packet.ip_typename ++ str " : logical inductive") ++
  fnl () ++
  pp_comment (str "with constructors : " ++
	      prvect_with_sep spc pr_id packet.ip_consnames) ++
  fnl ()

let pp_singleton kn packet =
  let name = pp_global Type (IndRef (kn,0)) in
  let l = rename_tvars keywords packet.ip_vars in
  hov 2 (str "type " ++ pp_parameters l ++ name ++ str " =" ++ spc () ++
	 pp_type false l (List.hd packet.ip_types.(0)) ++ fnl () ++
	 pp_comment (str "singleton inductive, whose constructor was " ++
		     pr_id packet.ip_consnames.(0)))

let pp_record kn fields ip_equiv packet =
  let ind = IndRef (kn,0) in
  let name = pp_global Type ind in
  let fieldnames = pp_fields ind fields in
  let l = List.combine fieldnames packet.ip_types.(0) in
  let pl = rename_tvars keywords packet.ip_vars in
  str "type " ++ pp_parameters pl ++ name ++
  pp_equiv pl name ip_equiv ++ str " = { "++
  hov 0 (prlist_with_sep (fun () -> str ";" ++ spc ())
	   (fun (p,t) -> p ++ str " : " ++ pp_type true pl t) l)
  ++ str " }"

let pp_coind pl name =
  let pl = rename_tvars keywords pl in
  pp_parameters pl ++ name ++ str " = " ++
  pp_parameters pl ++ str "__" ++ name ++ str " Lazy.t" ++
  fnl() ++ str "and "

let pp_ind co kn ind =
  let prefix = if co then "__" else "" in
  let initkwd = str "type " in
  let nextkwd = fnl () ++ str "and " in
  let names =
    Array.mapi (fun i p -> if p.ip_logical then mt () else
		  pp_global Type (IndRef (kn,i)))
      ind.ind_packets
  in
  let cnames =
    Array.mapi
      (fun i p -> if p.ip_logical then [||] else
	 Array.mapi (fun j _ -> pp_global Cons (ConstructRef ((kn,i),j+1)))
	   p.ip_types)
      ind.ind_packets
  in
  let rec pp i kwd =
    if i >= Array.length ind.ind_packets then mt ()
    else
      let ip = (kn,i) in
      let ip_equiv = ind.ind_equiv, i in
      let p = ind.ind_packets.(i) in
      if is_custom (IndRef ip) then pp (i+1) kwd
      else if p.ip_logical then pp_logical_ind p ++ pp (i+1) kwd
      else
	kwd ++ (if co then pp_coind p.ip_vars names.(i) else mt ()) ++
	pp_one_ind prefix ip_equiv p.ip_vars names.(i) cnames.(i) p.ip_types ++
	pp (i+1) nextkwd
  in
  pp 0 initkwd


(*s Pretty-printing of a declaration. *)

let pp_mind kn i =
  match i.ind_kind with
    | Singleton -> pp_singleton kn i.ind_packets.(0)
    | Coinductive -> pp_ind true kn i
    | Record fields -> pp_record kn fields (i.ind_equiv,0) i.ind_packets.(0)
    | Standard -> pp_ind false kn i

let pp_decl = function
    | Dtype (r,_,_) when is_inline_custom r -> mt ()
    | Dterm (r,_,_) when is_inline_custom r -> mt ()
    | Dind (kn,i) -> pp_mind kn i
    | Dtype (r, l, t) ->
        let name = pp_global Type r in
	let l = rename_tvars keywords l in
        let ids, def =
	  try
	    let ids,s = find_type_custom r in
	    pp_string_parameters ids, str " =" ++ spc () ++ str s
	  with Not_found ->
	    pp_parameters l,
	    if t == Taxiom then str " (* AXIOM TO BE REALIZED *)"
	    else str " =" ++ spc () ++ pp_type false l t
	in
	hov 2 (str "type " ++ ids ++ name ++ def)
    | Dterm (r, a, t) ->
	let def =
	  if is_custom r then str (" = " ^ find_custom r)
	  else if is_projection r then
	    (prvect str (Array.make (projection_arity r) " _")) ++
	    str " x = x."
	  else pp_function (empty_env ()) a
	in
	let name = pp_global Term r in
	let postdef = if is_projection r then name else mt () in
	pp_val name t ++ hov 0 (str "let " ++ name ++ def ++ postdef)
    | Dfix (rv,defs,typs) ->
	pp_Dfix (rv,defs,typs)

let pp_alias_decl ren = function
  | Dind (kn,i) -> pp_mind kn { i with ind_equiv = RenEquiv ren }
  | Dtype (r, l, _) ->
      let name = pp_global Type r in
      let l = rename_tvars keywords l in
      let ids = pp_parameters l in
      hov 2 (str "type " ++ ids ++ name ++ str " =" ++ spc () ++ ids ++
	     str (ren^".") ++ name)
  | Dterm (r, a, t) ->
      let name = pp_global Term r in
      hov 2 (str "let " ++ name ++ str (" = "^ren^".") ++ name)
  | Dfix (rv, _, _) ->
      prvecti (fun i r -> if is_inline_custom r then mt () else
		 let name = pp_global Term r in
		 hov 2 (str "let " ++ name ++ str (" = "^ren^".") ++ name) ++
		 fnl ())
	rv

let pp_spec = function
  | Sval (r,_) when is_inline_custom r -> mt ()
  | Stype (r,_,_) when is_inline_custom r -> mt ()
  | Sind (kn,i) -> pp_mind kn i
  | Sval (r,t) ->
      let def = pp_type false [] t in
      let name = pp_global Term r in
      hov 2 (str "val " ++ name ++ str " :" ++ spc () ++ def)
  | Stype (r,vl,ot) ->
      let name = pp_global Type r in
      let l = rename_tvars keywords vl in
      let ids, def =
	try
	  let ids, s = find_type_custom r in
	  pp_string_parameters ids, str " =" ++ spc () ++ str s
	with Not_found ->
	  let ids = pp_parameters l in
	  match ot with
	    | None -> ids, mt ()
	    | Some Taxiom -> ids, str " (* AXIOM TO BE REALIZED *)"
	    | Some t -> ids, str " =" ++ spc () ++ pp_type false l t
      in
      hov 2 (str "type " ++ ids ++ name ++ def)

let pp_alias_spec ren = function
  | Sind (kn,i) -> pp_mind kn { i with ind_equiv = RenEquiv ren }
  | Stype (r,l,_) ->
      let name = pp_global Type r in
      let l = rename_tvars keywords l in
      let ids = pp_parameters l in
      hov 2 (str "type " ++ ids ++ name ++ str " =" ++ spc () ++ ids ++
	     str (ren^".") ++ name)
  | Sval _ -> assert false

let rec pp_specif = function
  | (_,Spec (Sval _ as s)) -> pp_spec s
  | (l,Spec s) ->
      (try
	 let ren = Common.check_duplicate (top_visible_mp ()) l in
	 hov 1 (str ("module "^ren^" : sig") ++ fnl () ++ pp_spec s) ++
	 fnl () ++ str "end" ++ fnl () ++
	 pp_alias_spec ren s
       with Not_found -> pp_spec s)
  | (l,Smodule mt) ->
      let def = pp_module_type [] mt in
      let def' = pp_module_type [] mt in
      let name = pp_modname (MPdot (top_visible_mp (), l)) in
      hov 1 (str "module " ++ name ++ str " :" ++ fnl () ++ def) ++
      (try
	 let ren = Common.check_duplicate (top_visible_mp ()) l in
	 fnl () ++ hov 1 (str ("module "^ren^" :") ++ fnl () ++ def')
       with Not_found -> Pp.mt ())
  | (l,Smodtype mt) ->
      let def = pp_module_type [] mt in
      let name = pp_modname (MPdot (top_visible_mp (), l)) in
      hov 1 (str "module type " ++ name ++ str " =" ++ fnl () ++ def) ++
      (try
	 let ren = Common.check_duplicate (top_visible_mp ()) l in
	 fnl () ++ str ("module type "^ren^" = ") ++ name
       with Not_found -> Pp.mt ())

and pp_module_type params = function
  | MTident kn ->
      pp_modname kn
  | MTfunsig (mbid, mt, mt') ->
      let typ = pp_module_type [] mt in
      let name = pp_modname (MPbound mbid) in
      let def = pp_module_type (MPbound mbid :: params) mt' in
      str "functor (" ++ name ++ str ":" ++ typ ++ str ") ->" ++ fnl () ++ def
  | MTsig (mp, sign) ->
      push_visible mp params;
      let try_pp_specif l x =
        let px = pp_specif x in
        if Pp.is_empty px then l else px::l
      in
      (* We cannot use fold_right here due to side effects in pp_specif *)
      let l = List.fold_left try_pp_specif [] sign in
      let l = List.rev l in
      pop_visible ();
      str "sig" ++ fnl () ++
      v 1 (str " " ++ prlist_with_sep cut2 identity l) ++
	fnl () ++ str "end"
  | MTwith(mt,ML_With_type(idl,vl,typ)) ->
      let ids = pp_parameters (rename_tvars keywords vl) in
      let mp_mt = msid_of_mt mt in
      let l,idl' = List.sep_last idl in
      let mp_w =
	List.fold_left (fun mp l -> MPdot(mp,Label.of_id l)) mp_mt idl'
      in
      let r = ConstRef (Constant.make2 mp_w (Label.of_id l)) in
      push_visible mp_mt [];
      let pp_w = str " with type " ++ ids ++ pp_global Type r in
      pop_visible();
      pp_module_type [] mt ++ pp_w ++ str " = " ++ pp_type false vl typ
  | MTwith(mt,ML_With_module(idl,mp)) ->
      let mp_mt = msid_of_mt mt in
      let mp_w =
	List.fold_left (fun mp id -> MPdot(mp,Label.of_id id)) mp_mt idl
      in
      push_visible mp_mt [];
      let pp_w = str " with module " ++ pp_modname mp_w in
      pop_visible ();
      pp_module_type [] mt ++ pp_w ++ str " = " ++ pp_modname mp

let is_short = function MEident _ | MEapply _ -> true | _ -> false

let rec pp_structure_elem = function
  | (l,SEdecl d) ->
       (try
	 let ren = Common.check_duplicate (top_visible_mp ()) l in
	 hov 1 (str ("module "^ren^" = struct") ++ fnl () ++ pp_decl d) ++
	 fnl () ++ str "end" ++ fnl () ++
	 pp_alias_decl ren d
	with Not_found -> pp_decl d)
  | (l,SEmodule m) ->
      let typ =
        (* virtual printing of the type, in order to have a correct mli later*)
	if Common.get_phase () == Pre then
	  str ": " ++ pp_module_type [] m.ml_mod_type
	else mt ()
      in
      let def = pp_module_expr [] m.ml_mod_expr in
      let name = pp_modname (MPdot (top_visible_mp (), l)) in
      hov 1
	(str "module " ++ name ++ typ ++ str " =" ++
	 (if is_short m.ml_mod_expr then spc () else fnl ()) ++ def) ++
      (try
	 let ren = Common.check_duplicate (top_visible_mp ()) l in
	 fnl () ++ str ("module "^ren^" = ") ++ name
       with Not_found -> mt ())
  | (l,SEmodtype m) ->
      let def = pp_module_type [] m in
      let name = pp_modname (MPdot (top_visible_mp (), l)) in
      hov 1 (str "module type " ++ name ++ str " =" ++ fnl () ++ def) ++
      (try
	 let ren = Common.check_duplicate (top_visible_mp ()) l in
         fnl () ++ str ("module type "^ren^" = ") ++ name
       with Not_found -> mt ())

and pp_module_expr params = function
  | MEident mp -> pp_modname mp
  | MEapply (me, me') ->
      pp_module_expr [] me ++ str "(" ++ pp_module_expr [] me' ++ str ")"
  | MEfunctor (mbid, mt, me) ->
      let name = pp_modname (MPbound mbid) in
      let typ = pp_module_type [] mt in
      let def = pp_module_expr (MPbound mbid :: params) me in
      str "functor (" ++ name ++ str ":" ++ typ ++ str ") ->" ++ fnl () ++ def
  | MEstruct (mp, sel) ->
      push_visible mp params;
      let try_pp_structure_elem l x =
        let px = pp_structure_elem x in
        if Pp.is_empty px then l else px::l
      in
      (* We cannot use fold_right here due to side effects in pp_structure_elem *)
      let l = List.fold_left try_pp_structure_elem [] sel in
      let l = List.rev l in
      pop_visible ();
      str "struct" ++ fnl () ++
      v 1 (str " " ++ prlist_with_sep cut2 identity l) ++
      fnl () ++ str "end"

let rec prlist_sep_nonempty sep f = function
  | [] -> mt ()
  | [h] -> f h
  | h::t ->
     let e = f h in
     let r = prlist_sep_nonempty sep f t in
     if Pp.is_empty e then r
     else e ++ sep () ++ r

let do_struct f s =
  let ppl (mp,sel) =
    push_visible mp [];
    let p = prlist_sep_nonempty cut2 f sel in
    (* for monolithic extraction, we try to simulate the unavailability
       of [MPfile] in names by artificially nesting these [MPfile] *)
    (if modular () then pop_visible ()); p
  in
  let p = prlist_sep_nonempty cut2 ppl s in
  (if not (modular ()) then repeat (List.length s) pop_visible ());
  v 0 p ++ fnl ()

let pp_struct s = do_struct pp_structure_elem s

let pp_signature s = do_struct pp_specif s

let ocaml_descr = {
  keywords = keywords;
  file_suffix = ".ml";
  file_naming = file_of_modfile;
  preamble = preamble;
  pp_struct = pp_struct;
  sig_suffix = Some ".mli";
  sig_preamble = sig_preamble;
  pp_sig = pp_signature;
  pp_decl = pp_decl;
}