X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=ocaml%2Fsimple.ml;h=9de1f2a7c12444f2b651628d7d499e7e8497871b;hb=ad332f3befc4922498db7a9ca6dbb7cc67dbf75b;hp=991779e7ac995f5f980a174b43c292689cac1ce6;hpb=f1873841a3271d332cb8429b46e7bc7e0bca2402;p=fireball-separation.git

diff --git a/ocaml/simple.ml b/ocaml/simple.ml
index 991779e..9de1f2a 100644
--- a/ocaml/simple.ml
+++ b/ocaml/simple.ml
@@ -11,8 +11,6 @@ type t =
  | V of var
  | A of t * t
  | L of t
- | B (* bottom *)
- | C of int
 ;;
 
 let delta = L(A(V 0, V 0));;
@@ -23,7 +21,6 @@ let eta_eq' =
   | L t1, t2 -> aux l1 (l2+1) t1 t2
   | t1, L t2 -> aux (l1+1) l2 t1 t2
   | V a, V b -> a + l1 = b + l2
-  | C a, C b -> a = b
   | A(t1,t2), A(u1,u2) -> aux l1 l2 t1 u1 && aux l1 l2 t2 u2
   | _, _ -> false
  in aux ;;
@@ -49,10 +46,8 @@ let string_of_t =
   let rec string_of_term_w_pars level = function
     | V v -> if v >= level then "`" ^ string_of_int (v-level) else
        string_of_bvar (level - v-1)
-    | C n -> "c" ^ string_of_int n
     | A _
     | L _ as t -> "(" ^ string_of_term_no_pars level t ^ ")"
-    | B -> "BOT"
   and string_of_term_no_pars_app level = function
     | A(t1,t2) -> string_of_term_no_pars_app level t1 ^ " " ^ string_of_term_w_pars level t2
     | _ as t -> string_of_term_w_pars level t
@@ -68,19 +63,18 @@ type problem = {
  ; div : t
  ; conv : t
  ; sigma : (var * t) list (* substitutions *)
- ; stepped : var list
  ; phase : [`One | `Two] (* :'( *)
 }
 
 let string_of_problem p =
  let lines = [
-  "[stepped] " ^ String.concat " " (List.map string_of_int p.stepped);
   "[DV] " ^ string_of_t p.div;
   "[CV] " ^ string_of_t p.conv;
  ] in
  String.concat "\n" lines
 ;;
 
+exception B;;
 exception Done of (var * t) list (* substitution *);;
 exception Fail of int * string;;
 
@@ -98,8 +92,7 @@ let rec is_inert =
  function
  | A(t,_) -> is_inert t
  | V _ -> true
- | C _
- | L _ | B -> false
+ | L _ -> false
 ;;
 
 let is_var = function V _ -> true | _ -> false;;
@@ -111,26 +104,24 @@ let rec get_inert = function
  | _ -> assert false
 ;;
 
-let rec no_leading_lambdas hd_var j = function
- | L t -> 1 + no_leading_lambdas (hd_var+1) j t
- | A _ as t -> let hd_var', n = get_inert t in if hd_var = hd_var' then max 0 (j - n) else 0
- | V n -> if n = hd_var then j else 0
- | B | C _ -> 0
+(* precomputes the number of leading lambdas in a term,
+   after replacing _v_ w/ a term starting with n lambdas *)
+let rec no_leading_lambdas v n = function
+ | L t -> 1 + no_leading_lambdas (v+1) n t
+ | A _ as t -> let v', m = get_inert t in if v = v' then max 0 (n - m) else 0
+ | V v' -> if v = v' then n else 0
 ;;
 
 let rec subst level delift sub =
  function
  | V v -> if v = level + fst sub then lift level (snd sub) else V (if delift && v > level then v-1 else v)
- | L t -> let t = subst (level + 1) delift sub t in if t = B then B else L t
+ | L t -> L (subst (level + 1) delift sub t)
  | A (t1,t2) ->
   let t1 = subst level delift sub t1 in
   let t2 = subst level delift sub t2 in
   mk_app t1 t2
- | C _ as t -> t
- | B -> B
-and mk_app t1 t2 = if t2 = B || (t1 = delta && t2 = delta) then B
+and mk_app t1 t2 = if t1 = delta && t2 = delta then raise B
  else match t1 with
- | B -> B
  | L t1 -> subst 0 true (0, t2) t1
  | _ -> A (t1, t2)
 and lift n =
@@ -139,29 +130,26 @@ and lift n =
   | V m -> V (if m >= lev then m + n else m)
   | L t -> L (aux (lev+1) t)
   | A (t1, t2) -> A (aux lev t1, aux lev t2)
-  | C _ as t -> t
-  | B -> B
  in aux 0
 ;;
 let subst = subst 0 false;;
 
-let subst_in_problem sub p =
-print_endline ("-- SUBST " ^ string_of_t (V (fst sub)) ^ " |-> " ^ string_of_t (snd sub));
- {p with
-  div=subst sub p.div;
-  conv=subst sub p.conv;
-  stepped=(fst sub)::p.stepped;
-  sigma=sub::p.sigma}
+let subst_in_problem ((v, t) as sub) p =
+print_endline ("-- SUBST " ^ string_of_t (V v) ^ " |-> " ^ string_of_t t);
+ let sigma = sub::p.sigma in
+ let div = try subst sub p.div with B -> raise (Done sigma) in
+ let conv = try subst sub p.conv with B -> raise (Fail(-1,"p.conv diverged")) in
+ {p with div; conv; sigma}
 ;;
 
 let get_subterm_with_head_and_args hd_var n_args =
  let rec aux lev = function
- | C _
- | V _ | B -> None
+ | V _ -> None
  | L t -> aux (lev+1) t
  | A(t1,t2) as t ->
    let hd_var', n_args' = get_inert t1 in
    if hd_var' = hd_var + lev && n_args <= 1 + n_args'
+    (* the `+1` above is because of t2 *)
     then Some (lift ~-lev t)
     else match aux lev t2 with
     | None -> aux lev t1
@@ -173,8 +161,6 @@ let rec purify = function
  | L t -> Pure.L (purify t)
  | A (t1,t2) -> Pure.A (purify t1, purify t2)
  | V n -> Pure.V n
- | C _ -> Pure.V max_int (* FIXME *)
- | B -> Pure.B
 ;;
 
 let check p sigma =
@@ -182,7 +168,7 @@ let check p sigma =
  let div = purify p.div in
  let conv = purify p.conv in
  let sigma = List.map (fun (v,t) -> v, purify t) sigma in
- let freshno = List.fold_right (fun (x,_) -> max x) sigma 0 in
+ let freshno = List.fold_right (max ++ fst) sigma 0 in
  let env = Pure.env_of_sigma freshno sigma in
  assert (Pure.diverged (Pure.mwhd (env,div,[])));
  print_endline " D diverged.";
@@ -193,14 +179,14 @@ let check p sigma =
 
 let sanity p =
  print_endline (string_of_problem p); (* non cancellare *)
- if p.conv = B then problem_fail p "p.conv diverged";
- if p.div = B then raise (Done p.sigma);
  if p.phase = `Two && p.div = delta then raise (Done p.sigma);
  if not (is_inert p.div) then problem_fail p "p.div converged";
  p
 ;;
 
 (* drops the arguments of t after the n-th *)
+(* FIXME! E' usato in modo improprio contando sul fatto
+   errato che ritorna un inerte lungo esattamente n *)
 let inert_cut_at n t =
  let rec aux t =
   match t with
@@ -213,15 +199,19 @@ let inert_cut_at n t =
  in snd (aux t)
 ;;
 
-let find_eta_difference p t n_args =
- let t = inert_cut_at n_args t in
+(* return the index of the first argument with a difference
+   (the first argument is 0)
+   precondition: p.div and t have n+1 arguments
+   *)
+let find_eta_difference p t argsno =
+ let t = inert_cut_at argsno t in
  let rec aux t u k = match t, u with
- | V _, V _ -> assert false (* div subterm of conv *)
+ | V _, V _ -> problem_fail p "no eta difference found (div subterm of conv?)"
  | A(t1,t2), A(u1,u2) ->
-    if not (eta_eq t2 u2) then ((*print_endline((string_of_t t2) ^ " <> " ^ (string_of_t u2));*) k)
+    if not (eta_eq t2 u2) then (k-1)
     else aux t1 u1 (k-1)
  | _, _ -> assert false
- in aux p.div t n_args
+ in aux p.div t argsno
 ;;
 
 let compute_max_lambdas_at hd_var j =
@@ -235,7 +225,6 @@ let compute_max_lambdas_at hd_var j =
       else id) (max (aux hd t1) (aux hd t2))
  | L t -> aux (hd+1) t
  | V _ -> 0
- | _ -> assert false
  in aux hd_var
 ;;
 
@@ -288,9 +277,6 @@ print_cmd "STEP" ("on " ^ string_of_t (V var) ^ " (of:" ^ string_of_int n ^ ")")
  sanity p
 ;;
 
-;;
-
-
 let rec auto p =
  let hd_var, n_args = get_inert p.div in
  match get_subterm_with_head_and_args hd_var n_args p.conv with
@@ -303,7 +289,7 @@ let rec auto p =
       else auto p
     with Done sigma -> sigma)
  | Some t ->
-  let j = find_eta_difference p t n_args - 1 in
+  let j = find_eta_difference p t n_args in
   let k = 1 + max
    (compute_max_lambdas_at hd_var j p.div)
     (compute_max_lambdas_at hd_var j p.conv) in
@@ -326,7 +312,7 @@ let problem_of (label, div, convs, ps, var_names) =
  | Some div -> aux (div :> Num.nf)
  | None -> assert false in
  let varno = List.length var_names in
- let p = {orig_freshno=varno; freshno=1+varno; div; conv; sigma=[]; stepped=[]; phase=`One} in
+ let p = {orig_freshno=varno; freshno=1+varno; div; conv; sigma=[]; phase=`One} in
  (* initial sanity check *)
  sanity p
 ;;