typer.ml 29.1 KB
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(* TODO:
   rewrite type-checking of operators to propagate constraint *)

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(* I. Transform the abstract syntax of types and patterns into
      the internal form *)
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open Location
open Ast
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open Ident
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module S = struct type t = string let compare = compare end
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module TypeEnv = Map.Make(S)
module Env = Map.Make(Ident.Id)
(*
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module StringSet = Set.Make(S)
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*)
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exception NonExhaustive of Types.descr
exception Constraint of Types.descr * Types.descr * string
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exception ShouldHave of Types.descr * string
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exception WrongLabel of Types.descr * label
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exception UnboundId of string
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let raise_loc loc exn = raise (Location (loc,exn))
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(* Internal representation as a graph (desugar recursive types and regexp),
   to compute freevars, etc... *)

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type ti = {
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  id : int; 
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  mutable seen : bool;
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  mutable loc' : loc;
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  mutable fv : fv option; 
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  mutable descr': descr;
  mutable type_node: Types.node option;
  mutable pat_node: Patterns.node option
} 
and descr =
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  | IAlias of string * ti
  | IType of Types.descr
  | IOr of ti * ti
  | IAnd of ti * ti
  | IDiff of ti * ti
  | ITimes of ti * ti
  | IXml of ti * ti
  | IArrow of ti * ti
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  | IOptional of ti
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  | IRecord of bool * ti label_map
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  | ICapture of id
  | IConstant of id * Types.const
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type glb = ti TypeEnv.t
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let mk' =
  let counter = ref 0 in
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  fun loc ->
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    incr counter;
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    let rec x = { 
      id = !counter; 
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      seen = false;
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      loc' = loc; 
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      fv = None; 
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      descr' = IAlias ("__dummy__", x);
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      type_node = None; 
      pat_node = None 
    } in
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    x

let cons loc d =
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  let x = mk' loc in
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  x.descr' <- d;
  x
    
(* Note:
   Compilation of Regexp is implemented as a ``rewriting'' of
   the parsed syntax, in order to be able to print its result
   (for debugging for instance)
   
   It would be possible (and a little more efficient) to produce
   directly ti nodes.
*)
    
module Regexp = struct
  let defs = ref []
  let name =
    let c = ref 0 in
    fun () ->
      incr c;
      "#" ^ (string_of_int !c)

  let rec seq_vars accu = function
    | Epsilon | Elem _ -> accu
    | Seq (r1,r2) | Alt (r1,r2) -> seq_vars (seq_vars accu r1) r2
    | Star r | WeakStar r -> seq_vars accu r
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    | SeqCapture (v,r) -> seq_vars (IdSet.add v accu) r
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  let uniq_id = let r = ref 0 in fun () -> incr r; !r

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  type flat =  
    | REpsilon 
    | RElem of int * Ast.ppat  (* the int arg is used
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					    to stop generic comparison *)
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    | RSeq of flat * flat
    | RAlt of flat * flat
    | RStar of flat
    | RWeakStar of flat
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  let re_loc = ref noloc

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  let rec propagate vars : regexp -> flat = function
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    | Epsilon -> REpsilon
    | Elem x -> let p = vars x in RElem (uniq_id (),p)
    | Seq (r1,r2) -> RSeq (propagate vars r1,propagate vars r2)
    | Alt (r1,r2) -> RAlt (propagate vars r1, propagate vars r2)
    | Star r -> RStar (propagate vars r)
    | WeakStar r -> RWeakStar (propagate vars r)
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    | SeqCapture (v,x) -> 
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	let v= mk_loc !re_loc (Capture v) in
	propagate (fun p -> mk_loc !re_loc (And (vars p,v))) x
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  let dummy_pat = mknoloc (PatVar "DUMMY")
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  let cup r1 r2 =
    if r1 == dummy_pat then r2 else
      if r2 == dummy_pat then r1 else
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	mk_loc !re_loc (Or (r1,r2))
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(*TODO: review this compilation schema to avoid explosion when
  coding (Optional x) by  (Or(Epsilon,x)); memoization ... *)

  module Memo = Map.Make(struct type t = flat list let compare = compare end)
  module Coind = Set.Make(struct type t = flat list let compare = compare end)
  let memo = ref Memo.empty

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  let rec compile fin e seq : Ast.ppat = 
    if Coind.mem seq !e then dummy_pat
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    else (
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      e := Coind.add seq !e;
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      match seq with
	| [] ->
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	    fin
	| REpsilon :: rest -> 
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	    compile fin e rest
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	| RElem (_,p) :: rest -> 
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	    mk_loc !re_loc (Prod (p, guard_compile fin rest))
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	| RSeq (r1,r2) :: rest -> 
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	    compile fin e (r1 :: r2 :: rest)
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	| RAlt (r1,r2) :: rest -> 
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	    cup (compile fin e (r1::rest)) (compile fin e (r2::rest))
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	| RStar r :: rest -> 
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	    cup (compile fin e (r::seq)) (compile fin e rest) 
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	| RWeakStar r :: rest -> 
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	    cup (compile fin e rest) (compile fin e (r::seq))
    )
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  and guard_compile fin seq =
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    try Memo.find seq !memo
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    with
	Not_found ->
          let n = name () in
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	  let v = mk_loc !re_loc (PatVar n) in
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          memo := Memo.add seq v !memo;
	  let d = compile fin (ref Coind.empty) seq in
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	  assert (d != dummy_pat);
	  defs := (n,d) :: !defs;
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	  v

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(*
  type trans = [ `Alt of gnode * gnode | `Elem of Ast.ppat * gnode | `Final ]
  and gnode = 
      {
	mutable seen  : bool;
	mutable compile : bool;
	name  : string;
	mutable trans : trans;
      }

  let new_node() = { seen = false; compile = false; 
		     name = name(); trans = `Final }
  let to_compile = ref []

  let rec compile after = function
    | `Epsilon -> after
    | `Elem (_,p) -> 
	if not after.compile then (after.compile <- true; 
				   to_compile := after :: !to_compile);
	{ new_node () with trans = `Elem (p, after)  }
    | `Seq(r1,r2) -> compile (compile after r2) r1
    | `Alt(r1,r2) ->
	let r1 = compile after r1 and r2 = compile after r2 in
	{ new_node () with trans = `Alt (r1,r2) }
    | `Star r ->
	let n  = new_node() in
	n.trans <- `Alt (compile n r, after);
	n
    | `WeakStar r ->
	let n  = new_node() in
	n.trans <- `Alt (after, compile n r);
	n

  let seens = ref []	
  let rec collect_aux accu n =
    if n.seen then accu 
    else ( seens := n :: !seens;
	   match n.trans with
	     | `Alt (n1,n2) -> collect_aux (collect_aux accu n2) n1
	     | _ -> n :: accu
	 )

  let collect fin n =
    let l = collect_aux [] n in
    List.iter (fun n -> n.seen <- false) !seens;
    let l = List.map (fun n ->
			match n.trans with
			  | `Final -> fin
			  | `Elem (p,a) -> 
			      mk !re_loc (Prod(p, mk !re_loc (PatVar a.name)))
			  | _ -> assert false
		     ) l in
    match l with
      | h::t ->
	  List.fold_left (fun accu p -> mk !re_loc (Or (accu,p))) h t
      | _ -> assert false
*)    
	
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  let constant_nil t v = 
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    mk_loc !re_loc 
      (And (t, (mk_loc !re_loc (Constant (v, Types.Atom Sequence.nil_atom)))))
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  let compile loc regexp queue : ppat =
    re_loc := loc;
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    let vars = seq_vars IdSet.empty regexp in
    let fin = IdSet.fold constant_nil queue vars in
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    let re = propagate (fun p -> p) regexp in
    let n = guard_compile fin [re] in
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    memo := Memo.empty; 
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    let d = !defs in
    defs := [];
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(*
    let after = new_node() in
    let n = collect queue (compile after re) in
    let d = List.map (fun n -> (n.name, collect queue n)) !to_compile in
    to_compile := [];
*)

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    mk_loc !re_loc (Recurs (n,d))
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end

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let compile_regexp = Regexp.compile noloc
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let rec compile env { loc = loc; descr = d } : ti = 
  match (d : Ast.ppat') with
  | PatVar s -> 
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      (try TypeEnv.find s env
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       with Not_found -> 
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	 raise_loc_generic loc ("Undefined type variable " ^ s)
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      )
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  | Recurs (t, b) -> compile (compile_many env b) t
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  | Regexp (r,q) -> compile env (Regexp.compile loc r q)
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  | Internal t -> cons loc (IType t)
  | Or (t1,t2) -> cons loc (IOr (compile env t1, compile env t2))
  | And (t1,t2) -> cons loc (IAnd (compile env t1, compile env t2))
  | Diff (t1,t2) -> cons loc (IDiff (compile env t1, compile env t2))
  | Prod (t1,t2) -> cons loc (ITimes (compile env t1, compile env t2))
  | XmlT (t1,t2) -> cons loc (IXml (compile env t1, compile env t2))
  | Arrow (t1,t2) -> cons loc (IArrow (compile env t1, compile env t2))
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  | Optional t -> cons loc (IOptional (compile env t))
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  | Record (o,r) ->  cons loc (IRecord (o, LabelMap.map (compile env) r))
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  | Constant (x,v) -> cons loc (IConstant (x,v))
  | Capture x -> cons loc (ICapture x)
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and compile_many env b = 
  let b = List.map (fun (v,t) -> (v,t,mk' t.loc)) b in
  let env = 
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    List.fold_left (fun env (v,t,x) -> TypeEnv.add v x env) env b in
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  List.iter (fun (v,t,x) -> x.descr' <- IAlias (v, compile env t)) b;
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  env

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module IntSet = 
  Set.Make(struct type t = int let compare (x:int) y = compare x y end)

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let comp_fv_seen = ref []
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let comp_fv_res = ref IdSet.empty
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let rec comp_fv s =
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  match s.fv with
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    | Some fv -> comp_fv_res := IdSet.cup fv !comp_fv_res
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    | None ->
	(match s.descr' with
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	   | IAlias (_,x) -> 
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	       if x.seen then ()
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	       else ( 
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		 x.seen <- true;
		 comp_fv_seen := x :: !comp_fv_seen; 
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		 comp_fv x
	       ) 
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	   | IOr (s1,s2) 
	   | IAnd (s1,s2)
	   | IDiff (s1,s2)
	   | ITimes (s1,s2) | IXml (s1,s2)
	   | IArrow (s1,s2) -> comp_fv s1; comp_fv s2
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	   | IOptional r -> comp_fv r
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	   | IRecord (_,r) -> LabelMap.iter comp_fv r
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	   | IType _ -> ()
	   | ICapture x
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	   | IConstant (x,_) -> comp_fv_res := IdSet.add x !comp_fv_res
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	)
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let fv s =   
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  match s.fv with
    | Some l -> l
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    | None -> 
	comp_fv s;
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	let l = !comp_fv_res in
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	comp_fv_res := IdSet.empty;
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	List.iter (fun n -> n.seen <- false) !comp_fv_seen;
	comp_fv_seen := [];
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	s.fv <- Some l; 
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	l

let rec typ seen s : Types.descr =
  match s.descr' with
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    | IAlias (v,x) ->
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	if IntSet.mem s.id seen then 
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	  raise_loc_generic s.loc' 
	    ("Unguarded recursion on variable " ^ v ^ " in this type")
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	else typ (IntSet.add s.id seen) x
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    | IType t -> t
    | IOr (s1,s2) -> Types.cup (typ seen s1) (typ seen s2)
    | IAnd (s1,s2) ->  Types.cap (typ seen s1) (typ seen s2)
    | IDiff (s1,s2) -> Types.diff (typ seen s1) (typ seen s2)
    | ITimes (s1,s2) ->	Types.times (typ_node s1) (typ_node s2)
    | IXml (s1,s2) ->	Types.xml (typ_node s1) (typ_node s2)
    | IArrow (s1,s2) ->	Types.arrow (typ_node s1) (typ_node s2)
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    | IOptional s -> Types.Record.or_absent (typ seen s)
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    | IRecord (o,r) -> 
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	Types.record' 
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	  (o, LabelMap.map typ_node r)
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    | ICapture x | IConstant (x,_) -> assert false
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and typ_node s : Types.node =
  match s.type_node with
    | Some x -> x
    | None ->
	let x = Types.make () in
	s.type_node <- Some x;
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	let t = typ IntSet.empty s in
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	Types.define x t;
	x

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let type_node s = 
  let s = typ_node s in
  let s = Types.internalize s in
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(*  Types.define s (Types.normalize (Types.descr s)); *)
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  s
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let rec pat seen s : Patterns.descr =
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  if IdSet.is_empty (fv s) 
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  then Patterns.constr (Types.descr (type_node s)) 
  else
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    try pat_aux seen s
    with Patterns.Error e -> raise_loc_generic s.loc' e
      | Location (loc,exn) when loc = noloc -> raise (Location (s.loc', exn))


and pat_aux seen s = match s.descr' with
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  | IAlias (v,x) ->
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      if IntSet.mem s.id seen 
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      then raise 
	(Patterns.Error
	   ("Unguarded recursion on variable " ^ v ^ " in this pattern"));
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      pat (IntSet.add s.id seen) x
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  | IOr (s1,s2) -> Patterns.cup (pat seen s1) (pat seen s2)
  | IAnd (s1,s2) -> Patterns.cap (pat seen s1) (pat seen s2)
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  | IDiff (s1,s2) when IdSet.is_empty (fv s2) ->
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      let s2 = Types.neg (Types.descr (type_node s2)) in
      Patterns.cap (pat seen s1) (Patterns.constr s2)
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  | IDiff _ ->
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      raise (Patterns.Error "Difference not allowed in patterns")
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  | ITimes (s1,s2) -> Patterns.times (pat_node s1) (pat_node s2)
  | IXml (s1,s2) -> Patterns.xml (pat_node s1) (pat_node s2)
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  | IOptional _ -> 
      raise 
      (Patterns.Error 
	 "Optional field not allowed in record patterns")
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  | IRecord (o,r) ->
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      let pats = ref [] in
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      let aux l s = 
	if IdSet.is_empty (fv s) then type_node s
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	else
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	  ( pats := Patterns.record l (pat_node s) :: !pats;
	    Types.any_node )
      in
      let constr = Types.record' (o,LabelMap.mapi aux r) in
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      List.fold_left Patterns.cap (Patterns.constr constr) !pats
(* TODO: can avoid constr when o=true, and all fields have fv *)
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  | ICapture x ->  Patterns.capture x
  | IConstant (x,c) -> Patterns.constant x c
  | IArrow _ ->
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      raise (Patterns.Error "Arrow not allowed in patterns")
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  | IType _ -> assert false
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and pat_node s : Patterns.node =
  match s.pat_node with
    | Some x -> x
    | None ->
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	let x = Patterns.make (fv s) in
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	s.pat_node <- Some x;
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	let t = pat IntSet.empty s in
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	Patterns.define x t;
	x

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let mk_typ e =
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  if IdSet.is_empty (fv e) then type_node e
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  else raise_loc_generic e.loc' "Capture variables are not allowed in types"
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let typ glb e =
  mk_typ (compile glb e)

let pat glb e =
  pat_node (compile glb e)
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let register_global_types glb b =
  let env' = compile_many glb b in
  List.fold_left 
    (fun glb (v,{ loc = loc }) -> 
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       let t = TypeEnv.find v env' in
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       let d = Types.descr (mk_typ t) in
       (*	       let d = Types.normalize d in*)
       Types.Print.register_global v d;
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       if TypeEnv.mem v glb
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       then raise_loc_generic loc ("Multiple definition for type " ^ v);
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       TypeEnv.add v t glb
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    ) glb b
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(* II. Build skeleton *)

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module Fv = IdSet
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(* IDEA: introduce a node Loc in the AST to override nolocs
   in sub-expressions *)
   
let rec expr loc' glb { loc = loc; descr = d } = 
  let loc =  if loc = noloc then loc' else loc in
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  let (fv,td) = 
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    match d with
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      | Forget (e,t) ->
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	  let (fv,e) = expr loc glb e and t = typ glb t in
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	  (fv, Typed.Forget (e,t))
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      | Var s -> (Fv.singleton s, Typed.Var s)
      | Apply (e1,e2) -> 
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	  let (fv1,e1) = expr loc glb e1 and (fv2,e2) = expr loc glb e2 in
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	  (Fv.cup fv1 fv2, Typed.Apply (e1,e2))
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      | Abstraction a ->
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	  let iface = List.map (fun (t1,t2) -> (typ glb t1, typ glb t2)) 
			a.fun_iface in
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	  let t = List.fold_left 
		    (fun accu (t1,t2) -> Types.cap accu (Types.arrow t1 t2)) 
		    Types.any iface in
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	  let iface = List.map 
			(fun (t1,t2) -> (Types.descr t1, Types.descr t2)) 
			iface in
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	  let (fv0,body) = branches loc glb a.fun_body in
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	  let fv = match a.fun_name with
	    | None -> fv0
	    | Some f -> Fv.remove f fv0 in
	  (fv,
	   Typed.Abstraction 
	     { Typed.fun_name = a.fun_name;
	       Typed.fun_iface = iface;
	       Typed.fun_body = body;
	       Typed.fun_typ = t;
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	       Typed.fun_fv = fv
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	     }
	  )
      | Cst c -> (Fv.empty, Typed.Cst c)
      | Pair (e1,e2) ->
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	  let (fv1,e1) = expr loc glb e1 and (fv2,e2) = expr loc glb e2 in
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	  (Fv.cup fv1 fv2, Typed.Pair (e1,e2))
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      | Xml (e1,e2) ->
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	  let (fv1,e1) = expr loc glb e1 and (fv2,e2) = expr loc glb e2 in
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	  (Fv.cup fv1 fv2, Typed.Xml (e1,e2))
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      | Dot (e,l) ->
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	  let (fv,e) = expr loc glb e in
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	  (fv,  Typed.Dot (e,l))
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      | RemoveField (e,l) ->
	  let (fv,e) = expr loc glb e in
	  (fv,  Typed.RemoveField (e,l))
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      | RecordLitt r -> 
	  let fv = ref Fv.empty in
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	  let r = LabelMap.map 
		    (fun e -> 
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		       let (fv2,e) = expr loc glb e 
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		       in fv := Fv.cup !fv fv2; e)
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		    r in
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	  (!fv, Typed.RecordLitt r)
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      | Op (op,le) ->
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	  let (fvs,ltes) = List.split (List.map (expr loc glb) le) in
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	  let fv = List.fold_left Fv.cup Fv.empty fvs in
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	  (fv, Typed.Op (op,ltes))
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      | Match (e,b) -> 
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	  let (fv1,e) = expr loc glb e
	  and (fv2,b) = branches loc glb b in
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	  (Fv.cup fv1 fv2, Typed.Match (e, b))
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      | Map (e,b) ->
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	  let (fv1,e) = expr loc glb e
	  and (fv2,b) = branches loc glb b in
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	  (Fv.cup fv1 fv2, Typed.Map (e, b))
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      | Ttree (e,b) ->
	  let b = b @ [ (mknoloc (Internal Types.any)), mknoloc MatchFail ] in
	  let (fv1,e) = expr loc glb e
	  and (fv2,b) = branches loc glb b in
	  (Fv.cup fv1 fv2, Typed.Ttree (e, b))
      | MatchFail -> (Fv.empty, Typed.MatchFail)
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      | Try (e,b) ->
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	  let (fv1,e) = expr loc glb e
	  and (fv2,b) = branches loc glb b in
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	  (Fv.cup fv1 fv2, Typed.Try (e, b))
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  in
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  fv,
  { Typed.exp_loc = loc;
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    Typed.exp_typ = Types.empty;
    Typed.exp_descr = td;
  }
	      
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  and branches loc glb b = 
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    let fv = ref Fv.empty in
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    let accept = ref Types.empty in
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    let b = List.map 
	      (fun (p,e) ->
537
		 let (fv2,e) = expr loc glb e in
538
		 let p = pat glb p in
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		 let fv2 = Fv.diff fv2 (Patterns.fv p) in
		 fv := Fv.cup !fv fv2;
541
		 accept := Types.cup !accept (Types.descr (Patterns.accept p));
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		 { Typed.br_used = false;
543
		   Typed.br_pat = p;
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		   Typed.br_body = e }
	      ) b in
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    (!fv, 
     { 
       Typed.br_typ = Types.empty; 
       Typed.br_branches = b; 
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       Typed.br_accept = !accept;
       Typed.br_compiled = None;
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     } 
    )
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let expr = expr noloc

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let let_decl glb p e =
  let (_,e) = expr glb e in
  { Typed.let_pat = pat glb p;
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    Typed.let_body = e;
    Typed.let_compiled = None }

(* III. Type-checks *)

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let int_cup_record = Types.cup Types.Int.any Types.Record.any


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type env = Types.descr Env.t
569

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let match_fail = ref Types.empty

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open Typed

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let warning loc msg =
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  Format.fprintf !Location.warning_ppf "Warning %a:@\n%a%s@\n" 
    Location.print_loc loc
    Location.html_hilight loc
    msg
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let check loc t s msg =
  if not (Types.subtype t s) then raise_loc loc (Constraint (t, s, msg))

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let rec type_check env e constr precise = 
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(*  Format.fprintf Format.std_formatter "constr=%a precise=%b@\n"
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    Types.Print.print_descr constr precise; 
*)
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  let d = type_check' e.exp_loc env e.exp_descr constr precise in
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  e.exp_typ <- Types.cup e.exp_typ d;
  d

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and type_check' loc env e constr precise = match e with
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  | Forget (e,t) ->
      let t = Types.descr t in
      ignore (type_check env e t false);
      t
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  | Abstraction a ->
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      let t =
	try Types.Arrow.check_strenghten a.fun_typ constr 
	with Not_found -> 
	  raise_loc loc 
	  (ShouldHave
	     (constr, "but the interface of the abstraction is not compatible"))
      in
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      let env = match a.fun_name with
	| None -> env
	| Some f -> Env.add f a.fun_typ env in
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      List.iter 
	(fun (t1,t2) ->
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	   ignore (type_check_branches loc env t1 a.fun_body t2 false)
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	) a.fun_iface;
      t
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  | Match (e,b) ->
      let t = type_check env e b.br_accept true in
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      type_check_branches loc env t b constr precise
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  | Try (e,b) ->
      let te = type_check env e constr precise in
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      let tb = type_check_branches loc env Types.any b constr precise in
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      Types.cup te tb
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  | Pair (e1,e2) ->
      type_check_pair loc env e1 e2 constr precise
  | Xml (e1,e2) ->
      type_check_pair ~kind:`XML loc env e1 e2 constr precise
626

627
  | RecordLitt r ->
628
(* try to get rid of precise = true for values of fields *)
629
      if not (Types.Record.has_record constr) then
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	raise_loc loc (ShouldHave (constr,"but it is a record."));
      let (rconstr,res) = 
632
	List.fold_left
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	  (fun (rconstr,res) (l,e) ->
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	     (* could compute (split l e) once... *)
	     let pi = Types.Record.project_opt rconstr l in
	     if Types.is_empty pi then 
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	       raise_loc loc 
		 (ShouldHave (constr,(Printf.sprintf 
					"Field %s is not allowed here."
640
					(LabelPool.value l)
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				     )
			     ));
	     let t = type_check env e pi true in
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	     let rconstr = Types.Record.condition rconstr l t in
	     let res = if precise then (l,Types.cons t) :: res else res in
646
	     (rconstr,res)
647
	  ) (constr, []) (LabelMap.get r)
648
      in
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      if not (Types.Record.has_empty_record rconstr) then
	raise_loc loc 
	  (ShouldHave (constr,"More field should be present"));
      if precise then
	Types.record' (false, LabelMap.from_list (fun _ _ -> assert false) res)
      else constr
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  | Map (e,b) ->
      let t = type_check env e (Sequence.star b.br_accept) true in

      let constr' = Sequence.approx (Types.cap Sequence.any constr) in
      let exact = Types.subtype (Sequence.star constr') constr in
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      (* Note: 
	 - could be more precise by integrating the decomposition
	 of constr inside Sequence.map.
      *)
      let res = 
	Sequence.map 
	  (fun t -> 
667
	     type_check_branches loc env t b constr' (precise || (not exact)))
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	  t in
      if not exact then check loc res constr "";
      if precise then res else constr
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  | Op ("@", [e1;e2]) ->
      let constr' = Sequence.star 
		      (Sequence.approx (Types.cap Sequence.any constr)) in
      let exact = Types.subtype constr' constr in
      if exact then
	let t1 = type_check env e1 constr' precise
	and t2 = type_check env e2 constr' precise in
	if precise then Sequence.concat t1 t2 else constr
      else
	(* Note:
	   the knownledge of t1 may makes it useless to
	   check t2 with 'precise' ... *)
	let t1 = type_check env e1 constr' true
	and t2 = type_check env e2 constr' true in
	let res = Sequence.concat t1 t2 in
	check loc res constr "";
	if precise then res else constr
688
  | Apply (e1,e2) ->
689
(*
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      let constr' = Sequence.star 
		      (Sequence.approx (Types.cap Sequence.any constr)) in
      let t1 = type_check env e1 (Types.cup Types.Arrow.any constr') true in
      let t1_fun = Types.Arrow.get t1 in

      let has_fun = not (Types.Arrow.is_empty t1_fun)
      and has_seq = not (Types.subtype t1 Types.Arrow.any) in

      let constr' =
	Types.cap 
	  (if has_fun then Types.Arrow.domain t1_fun else Types.any)
	  (if has_seq then constr' else Types.any)
      in
      let need_arg = has_fun && Types.Arrow.need_arg t1_fun in
      let precise  = need_arg || has_seq in
      let t2 = type_check env e2 constr' precise in
      let res = Types.cup 
		  (if has_fun then 
		     if need_arg then Types.Arrow.apply t1_fun t2
		     else Types.Arrow.apply_noarg t1_fun
		   else Types.empty)
		  (if has_seq then Sequence.concat t1 t2
		   else Types.empty)
      in
      check loc res constr "";
      res
716
*)
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      let t1 = type_check env e1 Types.Arrow.any true in
      let t1 = Types.Arrow.get t1 in
      let dom = Types.Arrow.domain t1 in
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      let res =
	if Types.Arrow.need_arg t1 then
	  let t2 = type_check env e2 dom true in
	  Types.Arrow.apply t1 t2
	else
	  (ignore (type_check env e2 dom false); Types.Arrow.apply_noarg t1)
      in
      check loc res constr "";
      res
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741
  | Op ("flatten", [e]) ->
      let constr' = Sequence.star 
		      (Sequence.approx (Types.cap Sequence.any constr)) in
      let sconstr' = Sequence.star constr' in
      let exact = Types.subtype constr' constr in
      if exact then
	let t = type_check env e sconstr' precise in
	if precise then Sequence.flatten t else constr
      else
	let t = type_check env e sconstr' true in
	let res = Sequence.flatten t in
	check loc res constr "";
	if precise then res else constr
742
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  | _ -> 
      let t : Types.descr = compute_type' loc env e in
      check loc t constr "";
      t

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and type_check_pair ?(kind=`Normal) loc env e1 e2 constr precise =
  let rects = Types.Product.get ~kind constr in
  if Types.Product.is_empty rects then 
    (match kind with
      | `Normal -> raise_loc loc (ShouldHave (constr,"but it is a pair."))
      | `XML -> raise_loc loc (ShouldHave (constr,"but it is an XML element.")));
  let pi1 = Types.Product.pi1 rects in
  
  let t1 = type_check env e1 (Types.Product.pi1 rects) 
	     (precise || (Types.Product.need_second rects))in
  let rects = Types.Product.restrict_1 rects t1 in
  let t2 = type_check env e2 (Types.Product.pi2 rects) precise in
  if precise then 
    match kind with
      | `Normal -> Types.times (Types.cons t1) (Types.cons t2)
      | `XML -> Types.xml (Types.cons t1) (Types.cons t2)
  else
    constr


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769
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and compute_type env e =
  type_check env e Types.any true

and compute_type' loc env = function
771
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  | Var s -> 
      (try Env.find s env 
773
       with Not_found -> raise_loc loc (UnboundId (Id.value s))
774
      )
775
  | Cst c -> Types.constant c
776
777
778
779
  | Dot (e,l) ->
      let t = type_check env e Types.Record.any true in
         (try (Types.Record.project t l) 
          with Not_found -> raise_loc loc (WrongLabel(t,l)))
780
781
782
  | RemoveField (e,l) ->
      let t = type_check env e Types.Record.any true in
      Types.Record.remove_field t l
783
784
785
  | Op (op, el) ->
      let args = List.map (fun e -> (e.exp_loc, compute_type env e)) el in
      type_op loc op args
786
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788
789
790
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792
793
794
795
796
797
  | Ttree (e,b) ->
      let t = type_check env e Sequence.any true in
      let r = 
	Sequence.map_tree 
	  (fun t -> 
	     let res = type_check_branches loc env t b Sequence.any true in
	     let resid = !match_fail in
	     match_fail := Types.empty;
	     (res,resid)
	  ) t
      in
      r
798
799
800
801
802

(* We keep these cases here to allow comparison and benchmarking ...
   Just comment the corresponding cases in type_check' to
   activate these ones.
*)
803
804
805
  | Map (e,b) ->
      let t = compute_type env e in
      Sequence.map (fun t -> type_check_branches loc env t b Types.any true) t
806
807
808
809
810
  | Pair (e1,e2) -> 
      let t1 = compute_type env e1 
      and t2 = compute_type env e2 in
      Types.times (Types.cons t1) (Types.cons t2)
  | RecordLitt r ->
811
      let r = LabelMap.map (fun e -> Types.cons (compute_type env e)) r in
812
      Types.record' (false,r)
813
  | _ -> assert false
814

815
and type_check_branches loc env targ brs constr precise =
816
  if Types.is_empty targ then Types.empty 
817
818
  else (
    brs.br_typ <- Types.cup brs.br_typ targ;
819
    branches_aux loc env targ 
820
821
      (if precise then Types.empty else constr) 
      constr precise brs.br_branches
822
  )
823
    
824
825
and branches_aux loc env targ tres constr precise = function
  | [] -> raise_loc loc (NonExhaustive targ)
826
827
828
  | { br_body = { exp_descr = MatchFail } } :: _ ->
      match_fail := Types.cup !match_fail targ;
      tres
829
830
831
832
833
834
  | b :: rem ->
      let p = b.br_pat in
      let acc = Types.descr (Patterns.accept p) in

      let targ' = Types.cap targ acc in
      if Types.is_empty targ' 
835
      then branches_aux loc env targ tres constr precise rem
836
837
838
839
840
841
      else 
	( b.br_used <- true;
	  let res = Patterns.filter targ' p in
	  let env' = List.fold_left 
		       (fun env (x,t) -> Env.add x (Types.descr t) env) 
		       env res in
842
843
	  let t = type_check env' b.br_body constr precise in
	  let tres = if precise then Types.cup t tres else tres in
844
845
	  let targ'' = Types.diff targ acc in
	  if (Types.non_empty targ'') then 
846
	    branches_aux loc env targ'' tres constr precise rem 
847
848
	  else
	    tres
849
	)
850

851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
and type_let_decl env l =
  let acc = Types.descr (Patterns.accept l.let_pat) in
  let t = type_check env l.let_body acc true in
  let res = Patterns.filter t l.let_pat in
  List.map (fun (x,t) -> (x, Types.descr t)) res

and type_rec_funs env l =
  let types = 
    List.fold_left
      (fun accu -> function  {let_body={exp_descr=Abstraction a}} as l ->
	 let t = a.fun_typ in
	 let acc = Types.descr (Patterns.accept l.let_pat) in
	 if not (Types.subtype t acc) then
	   raise_loc l.let_body.exp_loc (NonExhaustive (Types.diff t acc));
	 let res = Patterns.filter t l.let_pat in
	 List.fold_left (fun accu (x,t) -> (x, Types.descr t)::accu) accu res
	 | _ -> assert false) [] l
  in
  let env' = List.fold_left (fun env (x,t) -> Env.add x t env) env types in
  List.iter 
    (function  { let_body = { exp_descr = Abstraction a } } as l ->
       ignore (type_check env' l.let_body Types.any false)
       | _ -> assert false) l;
  types


877
878
and type_op loc op args =
  match (op,args) with
879
    | "+", [loc1,t1; loc2,t2] ->
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
	check loc1 t1 int_cup_record
	"The first argument of + must be an integer or a record";
	let int = Types.Int.get t1 in
	let int = if Intervals.is_empty int then None else Some int in
	let r = if Types.Record.has_record t1 then Some t1 else None in
	(match (int,r) with
	   | Some t1, None ->
	       if not (Types.Int.is_int t2) then
		 raise_loc loc2
		   (Constraint 
		      (t2,Types.Int.any,
		       "The second argument of + must be an integer"));
	       Types.Int.put
		 (Intervals.add t1 (Types.Int.get t2));
	   | None, Some r1 ->
	       check loc2 t2 Types.Record.any 
	       "The second argument of + must be a record";
	       Types.Record.merge r1 t2
	   | None, None ->
	       Types.empty
	   | Some t1, Some r1 ->
	       check loc2 t2 int_cup_record
	       "The second argument of + must be an integer or a record";
	       Types.cup 
		 (Types.Int.put (Intervals.add t1 (Types.Int.get t2)))
		 (Types.Record.merge r1 t2)
	)
907
908
    | "-", [loc1,t1; loc2,t2] ->
	type_int_binop Intervals.sub loc1 t1 loc2 t2
909
    | ("*" | "/" | "mod"), [loc1,t1; loc2,t2] ->
910
	type_int_binop (fun i1 i2 -> Intervals.any) loc1 t1 loc2 t2
911
    | "@", [loc1,t1; loc2,t2] ->
912
913
914
	check loc1 t1 Sequence.any
	  "The first argument of @ must be a sequence";
	Sequence.concat t1 t2
915
    | "flatten", [loc1,t1] ->
916
917
918
	check loc1 t1 Sequence.seqseq 
	  "The argument of flatten must be a sequence of sequences";
	Sequence.flatten t1
919
920
921
922
    | "load_xml", [loc1,t1] ->
	check loc1 t1 Sequence.string
	  "The argument of load_xml must be a string (filename)";
	Types.any
923
924
925
926
    | "load_file", [loc1,t1] ->
	check loc1 t1 Sequence.string
	  "The argument of load_file must be a string (filename)";
	Sequence.string
927
928
929
930
    | "load_html", [loc1,t1] ->
	check loc1 t1 Sequence.string
	  "The argument of load_html must be a string (filename)";
	Types.any
931
932
    | "raise", [loc1,t1] ->
	Types.empty
933
934
    | "print_xml", [loc1,t1] ->
	Sequence.string
935
936
    | "print", [loc1,t1] ->
	check loc1 t1 Sequence.string
937
938
939
940
941
942
943
944
	  "The argument of print must be a string";
	Sequence.nil_type
    | "dump_to_file", [loc1,t1; loc2,t2] ->
	check loc1 t1 Sequence.string
	  "The argument of dump_to_file must be a string (filename)";
	check loc2 t2 Sequence.string
	  "The argument of dump_to_file must be a string (value to dump)";
	Sequence.nil_type
945
946
    | "int_of", [loc1,t1] ->
	check loc1 t1 Sequence.string
947
	  "The argument of int_of must be a string";
948
949
950
	if not (Types.subtype t1 Builtin.intstr) then
	  warning loc "This application of int_of may fail";
	Types.interval Intervals.any
951
952
    | "string_of", [loc1,t1] ->
	Sequence.string
953
    | "=", [loc1,t1; loc2,t2] ->
954
955
956
957
958
959
960
	(* could prevent comparision of functional value here... *)
	(* could also handle the case when t1 and t2 are the same 
	   singleton type *)
	if Types.is_empty (Types.cap t1 t2) then
	  Builtin.false_type
	else 
	  Builtin.bool
961
962
963
    | ("<=" | "<" | ">" | ">=" ), [loc1,t1; loc2,t2] ->
	(* could prevent comparision of functional value here... *)
	Builtin.bool
964
965
966
967
968
969
970
971
972
973
974
    | _ -> assert false

and type_int_binop f loc1 t1 loc2 t2 =
  if not (Types.Int.is_int t1) then
    raise_loc loc1 
      (Constraint 
	 (t1,Types.Int.any,
	  "The first argument must be an integer"));
  if not (Types.Int.is_int t2) then
    raise_loc loc2
      (Constraint 
975
	       (t2,Types.Int.any,
976
977
978
979
980
		"The second argument must be an integer"));
  Types.Int.put
    (f (Types.Int.get t1) (Types.Int.get t2));