Tentative implementation of strong separation algorithm

[fireball-separation.git] / ocaml / num.ml

diff --git a/ocaml/num.ml b/ocaml/num.ml
index 66e8a2df7ccb6ebd3e3cf98f741b043d910c5bbe..8ecf12491be1d9931dfdc39fbbe4c9403f391008 100644 (file)
--- a/ocaml/num.ml
+++ b/ocaml/num.ml
@@ -92,14 +92,23 @@ let free_vars = (List.map fst) ++ free_vars';;
 module ToScott =
 struct
 
+let delta = let open Pure in L(A(V 0, V 0))
+
+let bomb = ref(`Var(-1, -666));;
+
 let rec t_of_i_num_var =
  function
   | `N n -> Scott.mk_n n
-  | `Var(v,_) -> Pure.V v
+  | `Var(v,_) as x -> assert (x <> !bomb); Pure.V v
   | `Match(t,_,liftno,bs,args) ->
-      let bs = List.map (fun (n,t) -> n, t_of_nf (lift liftno t)) !bs in
+      let bs = List.map (
+        function (n,t) -> n,
+         (if t = !bomb then delta
+          else L (t_of_nf (lift (liftno+1) t)))
+        ) !bs in
       let t = t_of_i_num_var t in
       let m = Scott.mk_match t bs in
+      let m = Pure.A(m,delta) in
       List.fold_left (fun acc t -> Pure.A(acc,t_of_nf t)) m args
   | `I((v,_), args) -> Listx.fold_left (fun acc t -> Pure.A(acc,t_of_nf t)) (Pure.V v) args
 and t_of_nf =
@@ -118,7 +127,7 @@ let rec string_of_term =
  let boundvar x = "v" ^ string_of_int x in
  let varname lev l n =
   if n < lev then boundvar (lev-n-1)
-   else if n < List.length l then List.nth l (n-lev)
+   else if n - lev < List.length l then List.nth l (n-lev)
     else "`" ^ string_of_int (n-lev) in
  let rec string_of_term_w_pars lev l  = function
   | `Var(n,ar) -> varname lev l n ^ (if debug_display_arities then ":" ^ string_of_int ar else "")
@@ -127,7 +136,7 @@ let rec string_of_term =
   | `Lam _ as t -> "(" ^ string_of_term_no_pars_lam lev l t ^ ")"
   | `Match(t,(v,ar),bs_lift,bs,args) ->
       (* assert (bs_lift = lev); *)
-     "(["^ varname lev l v ^ (if debug_display_arities then ":"^ string_of_int ar else "") ^",match " ^ string_of_term_no_pars lev l (t :> nf) ^
+     "(["^ varname 0 l v ^ (if debug_display_arities then ":"^ string_of_int ar else "") ^",match " ^ string_of_term_no_pars lev l (t :> nf) ^
      " with " ^ String.concat " | " (List.map (fun (n,t) -> string_of_int n ^ " => " ^ string_of_term l (t :> nf)) !bs) ^ "] " ^
      String.concat " " (List.map (string_of_term l) (args :> nf list)) ^ ")"
  and string_of_term_no_pars_app lev l  = function
@@ -230,13 +239,16 @@ and subst truelam delift_by_one what (with_what : nf) (where : nf) =
    | `N _ as x -> x
    | `Match(t,v,bs_lift,bs,args) ->
        let bs_lift = bs_lift + if delift_by_one then -1 else 0 in
-       (* let l' = l - bs_lift  in *)
-       (* let with_what' = lift l' (with_what :> nf) in *)
+       (* Warning! It now applies again the substitution in branches of matches.
+          But careful, it does it many times, for every occurrence of
+          the match. This is okay because what does not occur in with_what. *)
+       let l' = l - bs_lift  in
+       let with_what' = lift l' (with_what :> nf) in
        (* The following line should be the identity when delift_by_one = true because we
           are assuming the ts to not contain lambda-bound variables. *)
-       (* bs := List.map (fun (n,t) -> n,subst truelam false what with_what' t) !bs ; *)
+       bs := List.map (fun (n,t) -> n,subst truelam false what with_what' t) !bs ;
        let body = cast_to_i_num_var (aux_i_num_var l t) in
-       mk_match body v bs_lift bs (List.map (aux l) args)
+       mk_match body v bs_lift bs (List.map (aux l) (args :> nf list))
  and aux l(*lift*) =
 (*function iii -> let res = match iii with*)
   function