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dot30-wip.v
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dot30-wip.v
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(* Full safety for DOT *)
(* copied from dot22.v *)
(* based on that, it removes the 2nd level of pushback,
and performs the necessary translation while going
from stp to stp2 *)
(* copied from dot24.v *)
(* based on that, it adds internal support for
non-variable path expressions *)
(* copied from dot26.v *)
(* based on that, it adds some static support for
non-variable path expressions *)
(* copied from dot27.v *)
(* based on that, it adds subsumption in static paths,
which requires derivation on stp size for stp_to_stp2,
due to mutual induction in matching static and dynamic stp and peval *)
(* copied from dot28.v *)
(* based on that, it adds value fields that can partake in paths *)
(* copied from dot29.v *)
(* based on that, it adds support for abstract variables in paths *)
(* TODO:
+ add pt_unpack (unpack in peval1)
- then we can remove stp_selb1/2
- make peval1 handle abstract vars, too
- then we can remove more stp/stp2 cases
towards fulldep:
- disable self vars in function terms
- prove total
- support application in paths
allow both total and recursive functions
- effect system?
*)
Require Export SfLib.
Require Export Arith.EqNat.
Require Export Arith.Le.
Require Import Coq.Program.Equality.
Module FSUB.
Definition id := nat.
Inductive var : Type :=
| varF : id -> var
| varH : id -> var
| varB : id -> var
with ty : Type :=
| TBool : ty
| TBot : ty
| TTop : ty
| TMem : id -> ty -> ty -> ty
| TSel : tm -> id -> ty
| TFld : id -> ty -> ty
| TAll : id -> ty -> ty -> ty
| TBind : ty -> ty
| TAnd : ty -> ty -> ty
| TOr : ty -> ty -> ty
with tm : Type :=
| ttrue : tm
| tfalse : tm
| tvar : var -> tm
| tsel : tm -> id -> tm
| tapp : tm -> id -> tm -> tm (* \o.m(x) *)
| tobj : id -> list (id * def) -> tm (* \o {d} *)
| tlet : id -> tm -> tm -> tm (* let \x = t1 in t2 *)
with def : Type :=
| dfld : id(*var*) -> def
| dfun : id -> tm -> def
| dmem : ty -> def
.
Inductive vl : Type :=
| vbool : bool -> vl
| vobj : list (id*vl) -> id -> list (id * def) -> vl
.
Definition tenv := list (id*ty).
Definition venv := list (id*vl).
Definition aenv := list (id*(venv*ty)).
Hint Unfold venv.
Hint Unfold tenv.
Fixpoint fresh {X: Type} (l : list (id * X)): nat :=
match l with
| [] => 0
| (n',a)::l' => 1 + n'
end.
Fixpoint index {X : Type} (n : id) (l : list (id * X)) : option X :=
match l with
| [] => None
| (n',a) :: l' =>
if le_lt_dec (fresh l') n' then
if (beq_nat n n') then Some a else index n l'
else None
end.
Fixpoint tail {X : Type} (n : id) (l : list (id * X)) : list (id * X) :=
match l with
| [] => []
| (n',a) :: l' => (* DeBrujin *)
if (beq_nat n (fresh l)) then l else tail n l' (* XXX use < ? *)
end.
Fixpoint indexr {X : Type} (n : id) (l : list (id * X)) : option X :=
match l with
| [] => None
| (n',a) :: l' => (* DeBrujin *)
if (beq_nat n (length l')) then Some a else indexr n l'
end.
Fixpoint tailr {X : Type} (n : id) (l : list (id * X)) : list (id * X) :=
match l with
| [] => []
| (n',a) :: l' => (* DeBrujin *)
if (beq_nat n (length l)) then l else tailr n l'
end.
(*
Fixpoint update {X : Type} (n : nat) (x: X)
(l : list X) { struct l }: list X :=
match l with
| [] => []
| a :: l' => if beq_nat n (length l') then x::l' else a :: update n x l'
end.
*)
(* LOCALLY NAMELESS *)
(* TODO: add j and check x < j for (varF x). swap order of k/l. *)
Inductive closed_rec: nat -> nat -> ty -> Prop :=
| cl_top: forall k l,
closed_rec k l TTop
| cl_bot: forall k l,
closed_rec k l TBot
| cl_bool: forall k l,
closed_rec k l TBool
| cl_mem: forall k l m T1 T2,
closed_rec k l T1 ->
closed_rec k l T2 ->
closed_rec k l (TMem m T1 T2)
| cl_fld: forall k l m T2,
closed_rec k l T2 ->
closed_rec k l (TFld m T2)
| cl_all: forall k l m T1 T2,
closed_rec k l T1 ->
closed_rec (S k) l T2 ->
closed_rec k l (TAll m T1 T2)
| cl_bind: forall k l T2,
closed_rec (S k) l T2 ->
closed_rec k l (TBind T2)
| cl_sel: forall k l p m,
closed_path k l p ->
closed_rec k l (TSel p m)
| cl_and: forall k l T1 T2,
closed_rec k l T1 ->
closed_rec k l T2 ->
closed_rec k l (TAnd T1 T2)
| cl_or: forall k l T1 T2,
closed_rec k l T1 ->
closed_rec k l T2 ->
closed_rec k l (TOr T1 T2)
with closed_path: nat -> nat -> tm -> Prop :=
| clp_var: forall k l x,
closed_path k l (tvar (varF x))
| clp_vara: forall k l x,
l > x ->
closed_path k l (tvar (varH x))
| clp_varb: forall k l i,
k > i ->
closed_path k l (tvar (varB i))
| clp_sel: forall k l p m,
closed_path k l p ->
closed_path k l (tsel p m)
.
Hint Constructors closed_rec.
Definition closed j l T := closed_rec j l T.
Fixpoint open_rec (k: nat) (u: tm) (T: ty) { struct T }: ty :=
match T with
| TSel p m => TSel (open_path k u p) m
| TAll m T1 T2 => TAll m (open_rec k u T1) (open_rec (S k) u T2)
| TBind T2 => TBind (open_rec (S k) u T2)
| TTop => TTop
| TBot => TBot
| TBool => TBool
| TFld m T2 => TFld m (open_rec k u T2)
| TMem m T1 T2 => TMem m (open_rec k u T1) (open_rec k u T2)
| TAnd T1 T2 => TAnd (open_rec k u T1) (open_rec k u T2)
| TOr T1 T2 => TOr (open_rec k u T1) (open_rec k u T2)
end
with open_path (k: nat) (u: tm) (t: tm) { struct t }: tm :=
match t with
| tvar (varF x) => tvar (varF x) (* free var remains free. functional, so we can't check for conflict *)
| tvar (varH x) => tvar (varH x)
| tvar (varB i) => (if beq_nat k i then u else tvar (varB i))
| ttrue => ttrue
| tfalse => tfalse
| tsel p m => tsel (open_path k u p) m
| tapp t1 m t2 => tapp (open_path k u t1) m (open_path k u t2)
| tlet m t1 t2 => tlet m (open_path k u t1) (open_path k u t2)
| tobj a b => tobj a b (* TODO: go deep? right now tobj can't occur in path ... *)
end.
Definition open u T := open_rec 0 u T.
(* sanity check *)
Example open_ex1: open (tvar (varF 9)) (TAll 0 TBool (TAll 0 (TSel (tvar (varB 1)) 0) (TSel (tvar (varB 1)) 0))) =
(TAll 0 TBool (TAll 0 (TSel (tvar (varF 9)) 0) (TSel (tvar (varB 1)) 0))).
Proof. compute. eauto. Qed.
Fixpoint subst (U : tm) (T : ty) {struct T} : ty :=
match T with
| TTop => TTop
| TBot => TBot
| TBool => TBool
| TMem m T1 T2 => TMem m (subst U T1) (subst U T2)
| TSel p m => TSel (subst_path U p) m
| TFld m T2 => TFld m (subst U T2)
| TAll m T1 T2 => TAll m (subst U T1) (subst U T2)
| TBind T2 => TBind (subst U T2)
| TAnd T1 T2 => TAnd (subst U T1) (subst U T2)
| TOr T1 T2 => TOr (subst U T1) (subst U T2)
end
with subst_path (U : tm) (t : tm) {struct t} : tm :=
match t with
| tvar (varF x) => tvar (varF x)
| tvar (varB i) => tvar (varB i)
| tvar (varH i) => if beq_nat i 0 then U else (tvar (varH (i-1)))
| ttrue => ttrue
| tfalse => tfalse
| tsel p m => tsel (subst_path U p) m
| tapp t1 m t2 => tapp (subst_path U t1) m (subst_path U t2)
| tlet m t1 t2 => tlet m (subst_path U t1) (subst_path U t2)
| tobj a b => tobj a b (* TODO: go deep? right now tobj can't occur in path ... *)
end.
Fixpoint nosubst (T : ty) {struct T} : Prop :=
match T with
| TTop => True
| TBot => True
| TBool => True
| TMem m T1 T2 => nosubst T1 /\ nosubst T2
| TSel p m => True
| TFld m T2 => nosubst T2
| TAll m T1 T2 => nosubst T1 /\ nosubst T2
| TBind T2 => nosubst T2
| TAnd T1 T2 => nosubst T1 /\ nosubst T2
| TOr T1 T2 => nosubst T1 /\ nosubst T2
end
with nosubst_path (t : tm) {struct t} : Prop :=
match t with
| tvar (varF x) => True
| tvar (varB i) => True
| tvar (varH i) => i <> 0
| ttrue => True
| tfalse => True
| tsel p m => nosubst_path p
| tapp t1 m t2 => nosubst_path t1 /\ nosubst_path t2
| tlet m t1 t2 => nosubst_path t1 /\ nosubst_path t2
| tobj a b => True (* TODO: go deep? right now tobj can't occur in path ... *)
end.
Fixpoint fresh_in_term (t:tm): nat :=
match t with
| ttrue => 0
| tfalse => 0
| tvar (varF n) => S n
| tvar x => 0
| tsel f l => fresh_in_term f
| tapp f l x => max (fresh_in_term f) (fresh_in_term x)
| tobj n ds => n
| tlet n x y => n
end.
Fixpoint freshH_in_term (t:tm): nat :=
match t with
| ttrue => 0
| tfalse => 0
| tvar (varH n) => S n
| tvar x => 0
| tsel f l => freshH_in_term f
| tapp f l x => max (freshH_in_term f) (freshH_in_term x)
| tobj n ds => n
| tlet n x y => n
end.
Hint Unfold open.
Hint Unfold closed.
Fixpoint path_head (t: tm) : option var :=
match t with
| tvar x => Some x
| tsel t1 l => path_head t1
| _ => None
end.
(* TODO: var *)
(* QUESTION: include trans rule or not? sela1 rules use restricted GL now, so trans seems useful *)
Inductive stp: tenv -> tenv -> ty -> ty -> nat -> Prop :=
| stp_topx: forall G1 GH n1,
stp G1 GH TTop TTop (S n1)
| stp_botx: forall G1 GH n1,
stp G1 GH TBot TBot (S n1)
| stp_top: forall G1 GH T1 n1,
stp G1 GH T1 T1 n1 -> (* regularity *)
stp G1 GH T1 TTop (S n1)
| stp_bot: forall G1 GH T2 n1,
stp G1 GH T2 T2 n1 -> (* regularity *)
stp G1 GH TBot T2 (S n1)
| stp_bool: forall G1 GH n1,
stp G1 GH TBool TBool (S n1)
| stp_fld: forall G1 GH m T2 T4 n1,
stp G1 GH T2 T4 n1 ->
stp G1 GH (TFld m T2) (TFld m T4) (S n1)
| stp_mem: forall G1 GH m T1 T2 T3 T4 n1 n2,
stp G1 GH T3 T1 n1 ->
stp G1 GH T2 T4 n2 ->
stp G1 GH (TMem m T1 T2) (TMem m T3 T4) (S (n1+n2))
| stp_sel1: forall G1 GH GL m T2 x n1 n3,
tailr (freshH_in_term x) GH = GL ->
peval1 x G1 GL (TMem m TBot T2) n1 ->
stp G1 GH T2 T2 n3 -> (* regularity of stp2 *)
stp G1 GH (TSel x m) T2 (S (n1+n3))
| stp_sel2: forall G1 GH GL m T1 x n1 n3,
tailr (freshH_in_term x) GH = GL ->
peval1 x G1 GL (TMem m T1 TTop) n1 ->
stp G1 GH T1 T1 n3 -> (* regularity of stp2 *)
stp G1 GH T1 (TSel x m) (S (n1+n3))
| stp_selx: forall G1 GH GL TX x m n1,
tailr (freshH_in_term x) GH = GL ->
peval1 x G1 GL TX n1 ->
stp G1 GH (TSel x m) (TSel x m) (S n1)
| stp_all: forall G1 GH m T1 T2 T3 T4 x n1 n2 n3,
stp G1 GH T3 T1 n1 ->
x = length GH ->
closed 1 (length GH) T2 -> (* must not accidentally bind x *)
closed 1 (length GH) T4 ->
stp G1 ((0,T1)::GH) (open (tvar (varH x)) T2) (open (tvar (varH x)) T2) n2 -> (* regularity *)
stp G1 ((0,T3)::GH) (open (tvar (varH x)) T2) (open (tvar (varH x)) T4) n3 ->
stp G1 GH (TAll m T1 T2) (TAll m T3 T4) (S (n1+n2+n3))
| stp_bindx: forall G1 GH T1 T2 x n1 n2,
x = length GH ->
closed 1 (length GH) T1 -> (* must not accidentally bind x *)
closed 1 (length GH) T2 ->
stp G1 ((0,open (tvar (varH x)) T2)::GH) (open (tvar (varH x)) T2) (open (tvar (varH x)) T2) n1 -> (* regularity *)
stp G1 ((0,open (tvar (varH x)) T1)::GH) (open (tvar (varH x)) T1) (open (tvar (varH x)) T2) n2 ->
stp G1 GH (TBind T1) (TBind T2) (S (n1+n2))
| stp_bind1: forall G1 GH T1 T2 x n1 n2,
x = length GH ->
closed 1 (length GH) T1 -> (* must not accidentally bind x *)
closed 0 (length GH) T2 ->
stp G1 GH T2 T2 n1 ->
stp G1 ((0,open (tvar (varH x)) T1)::GH) (open (tvar (varH x)) T1) T2 n2 ->
stp G1 GH (TBind T1) T2 (S (n1+n2))
| stp_and11: forall G GH T1 T2 T n1 n2,
stp G GH T1 T n1 ->
stp G GH T2 T2 n2 -> (* regularity *)
stp G GH (TAnd T1 T2) T (S (n1+n2))
| stp_and12: forall G GH T1 T2 T n1 n2,
stp G GH T2 T n1 ->
stp G GH T1 T1 n2 -> (* regularity *)
stp G GH (TAnd T1 T2) T (S (n1+n2))
| stp_and2: forall G GH T1 T2 T n1 n2,
stp G GH T T1 n1 ->
stp G GH T T2 n2 ->
stp G GH T (TAnd T1 T2) (S (n1+n2))
| stp_or21: forall G GH T1 T2 T n1 n2,
stp G GH T T1 n1 ->
stp G GH T2 T2 n2 -> (* regularity *)
stp G GH T (TOr T1 T2) (S (n1+n2))
| stp_or22: forall G GH T1 T2 T n1 n2,
stp G GH T T2 n1 ->
stp G GH T1 T1 n2 -> (* regularity *)
stp G GH T (TOr T1 T2) (S (n1+n2))
| stp_or1: forall G GH T1 T2 T n1 n2,
stp G GH T1 T n1 ->
stp G GH T2 T n2 ->
stp G GH (TOr T1 T2) T (S (n1+n2))
with peval1: tm -> tenv -> tenv -> ty -> nat -> Prop :=
| pt_var: forall x G1 GH TX n1,
index x G1 = Some TX ->
peval1 (tvar (varF x)) G1 GH TX (S n1)
| pt_vara: forall x G1 GH TX n1,
indexr x GH = Some TX -> (* TODO: need to constrain GH to GL? *)
peval1 (tvar (varH x)) G1 GH TX (S n1)
| pt_sel: forall f l G1 GH TX n1 n2,
peval1 f G1 GH (TFld l TX) n1 ->
stp G1 GH TX TX n2 ->
peval1 (tsel f l) G1 GH TX (S (n1+n2))
| pt_sub: forall t1 G1 GH T1 T2 n1 n2,
peval1 t1 G1 GH T1 n1 ->
stp G1 GH T1 T2 n2 ->
peval1 t1 G1 GH T2 (S (n1+n2))
| pt_unpack: forall t1 G1 GH T1 n1 n2,
peval1 t1 G1 GH (TBind T1) n1 ->
stp G1 GH (open t1 T1) (open t1 T1) n2 ->
peval1 t1 G1 GH (open t1 T1) (S (n1+n2))
.
(* TODO: sanity check -- prove these are admissible as lemmas *)
(*
| stp_sel1: forall G1 GH TX m T2 x,
index x G1 = Some TX ->
closed 0 0 TX ->
stp G1 [] TX (TMem m TBot T2) ->
stp G1 GH T2 T2 -> (* regularity of stp2 *)
stp G1 GH (TSel (varF x) m) T2
| stp_sel2: forall G1 GH TX m T1 x,
index x G1 = Some TX ->
closed 0 0 TX ->
stp G1 [] TX (TMem m T1 TTop) ->
stp G1 GH T1 T1 -> (* regularity of stp2 *)
stp G1 GH T1 (TSel (varF x) m)
| stp_selb1: forall G1 GH TX m T2 x,
index x G1 = Some TX ->
stp G1 [] TX (TBind (TMem m TBot T2)) -> (* Note GH = [] *)
stp G1 GH (open (varF x) T2) (open (varF x) T2) -> (* regularity *)
stp G1 GH (TSel (varF x) m) (open (varF x) T2)
| stp_selb2: forall G1 GH TX m T1 x,
index x G1 = Some TX ->
stp G1 [] TX (TBind (TMem m T1 TTop)) -> (* Note GH = [] *)
stp G1 GH (open (varF x) T1) (open (varF x) T1) -> (* regularity *)
stp G1 GH (open (varF x) T1) (TSel (varF x) m)
| stp_selx: forall G1 GH TX x m,
index x G1 = Some TX ->
stp G1 GH (TSel (varF x) m) (TSel (varF x) m)
| stp_sela1: forall G1 GH GL TX m T2 x,
tailr (S x) GH = (0,TX)::GL ->
stp G1 ((0,TX)::GL) TX (TMem m TBot T2) ->
stp G1 GH T2 T2 -> (* regularity *)
stp G1 GH (TSel (varH x) m) T2
| stp_sela2: forall G1 GH GL TX m T1 x,
tailr (S x) GH = (0,TX)::GL ->
stp G1 ((0,TX)::GL) TX (TMem m T1 TTop) -> (* not using self name for now *)
stp G1 GH T1 T1 -> (* regularity of stp2 *)
stp G1 GH T1 (TSel (varH x) m)
| stp_selab1: forall G1 GH GL TX m T2 T2' x,
tailr (S x) GH = (0,TX)::GL ->
closed 0 x (TBind (TMem m TBot T2)) ->
stp G1 ((0,TX)::GL) TX (TBind (TMem m TBot T2)) ->
T2' = (open (varH x) T2) ->
stp G1 GH T2' T2' -> (* regularity *)
stp G1 GH (TSel (varH x) m) T2'
| stp_selab2: forall G1 GH GL TX m T1 T1' x,
tailr (S x) GH = (0,TX)::GL ->
closed 0 x (TBind (TMem m T1 TTop)) ->
stp G1 ((0,TX)::GL) TX (TBind (TMem m T1 TTop)) ->
T1' = (open (varH x) T1) ->
stp G1 GH T1' T1' -> (* regularity *)
stp G1 GH T1' (TSel (varH x) m)
| stp_selax: forall G1 GH TX x m,
indexr x GH = Some TX ->
stp G1 GH (TSel (varH x) m) (TSel (varH x) m)
*)
Hint Constructors peval1.
Hint Constructors stp.
Function tand (t1: ty) (t2: ty) :=
match t2 with
| TTop => t1
| _ => TAnd t1 t2
end.
Definition stpd G1 GH T1 T2 := exists n, stp G1 GH T1 T2 n.
Definition pevald1 x G1 GH TX := exists n, peval1 x G1 GH TX n.
Hint Unfold stpd.
Hint Unfold pevald1.
(* TODO *)
Inductive has_type : tenv -> tm -> ty -> Prop :=
| t_true: forall env,
has_type env ttrue TBool
| t_false: forall env,
has_type env tfalse TBool
| t_var: forall x env T1 n1,
index x env = Some T1 ->
stp env [] T1 T1 n1 ->
has_type env (tvar (varF x)) T1
| t_var_pack: forall x env T1 n1,
has_type env (tvar (varF x)) (open (tvar (varF x)) T1) -> (* todo: relax *)
stp env [] (TBind T1) (TBind T1) n1 ->
has_type env (tvar (varF x)) (TBind T1)
| t_var_unpack: forall x env T1 n1,
has_type env (tvar (varF x)) (TBind T1) ->
stp env [] (open (tvar (varF x)) T1) (open (tvar (varF x)) T1) n1 ->
has_type env (tvar (varF x)) (open (tvar (varF x)) T1)
| t_sel_unpack: forall x l env T1 n1 n2,
has_type env (tsel x l) (TBind T1) ->
peval1 (tsel x l) env [] (TBind T1) n2 -> (* make sure it's actually a path! *)
stp env [] (open (tsel x l) T1) (open (tsel x l) T1) n1 ->
has_type env (tsel x l) (open (tsel x l) T1)
| t_obj: forall env f ds T TX n1 n2,
fresh env = f ->
open (tvar (varF f)) T = TX ->
dcs_has_type ((f, TX)::env) f ds T ->
stp ((f, TX)::env) [] TX TX n1 ->
stp env [] (TBind T) (TBind T) n2 ->
has_type env (tobj f ds) (TBind T)
| t_sel: forall env f l T2 n1,
has_type env f (TFld l T2) ->
stp env [] T2 T2 n1 ->
has_type env (tsel f l) T2
| t_app: forall env f l x T1 T2 n1,
has_type env f (TAll l T1 T2) ->
has_type env x T1 ->
stp env [] T2 T2 n1 ->
has_type env (tapp f l x) T2
| t_app_var: forall env f l x T1 T2 T2X n1,
has_type env f (TAll l T1 T2) ->
has_type env (tvar (varF x)) T1 ->
open (tvar (varF x)) T2 = T2X ->
stp env [] T2X T2X n1 ->
has_type env (tapp f l (tvar (varF x))) T2X
| t_let: forall env x ex e Tx T n1,
has_type env ex Tx ->
fresh env <= x ->
has_type ((x, Tx)::env) e T ->
stp env [] T T n1 ->
has_type env (tlet x ex e) T
| t_sub: forall env e T1 T2 n1,
has_type env e T1 ->
stp env [] T1 T2 n1 ->
has_type env e T2
with dcs_has_type: tenv -> id -> list (id * def) -> ty -> Prop :=
| dt_nil: forall env f,
dcs_has_type env f nil TTop
| dt_fld: forall env f y m T2 dcs TS T,
has_type env (tvar (varF y)) (open (tvar (varF f)) T2) ->
index y env = Some (open (tvar (varF f)) T2) -> y <> f -> (* TODO: these are extra simplif *)
dcs_has_type env f dcs TS ->
m = length dcs ->
T = tand (TFld m T2) TS ->
dcs_has_type env f ((m, dfld y)::dcs) T
| dt_fun: forall env f x y m T1 T2 dcs TS T,
has_type ((x,open (tvar (varF f)) T1)::env) y (open (tvar (varF x)) (open_rec 1 (tvar (varF f)) T2)) ->
dcs_has_type env f dcs TS ->
fresh env = x ->
m = length dcs ->
T = tand (TAll m T1 T2) TS ->
dcs_has_type env f ((m, dfun x y)::dcs) T
| dt_mem: forall env f m T1 dcs TS T,
dcs_has_type env f dcs TS ->
m = length dcs ->
T = tand (TMem m T1 T1) TS ->
dcs_has_type env f ((m, dmem T1)::dcs) T
.
(*
None means timeout
Some None means stuck
Some (Some v)) means result v
Could use do-notation to clean up syntax.
*)
Fixpoint teval(n: nat)(env: venv)(t: tm){struct n}: option (option vl) :=
match n with
| 0 => None
| S n =>
match t with
| ttrue => Some (Some (vbool true))
| tfalse => Some (Some (vbool false))
| tvar (varF x) => Some (index x env)
| tvar _ => Some None
| tobj f ds => Some (Some (vobj env f ds)) (* TODO: take subenv < f, also in has_type *)
| tsel ef m =>
match teval n env ef with
| None => None
| Some None => Some None
| Some (Some (vbool _)) => Some None
| Some (Some (vobj env2 f ds)) =>
match index m ds with
| None => Some None
| Some (dmem _) => Some None
| Some (dfun _ _) => Some None
| Some (dfld y) => teval n ((f,vobj env2 f ds)::env2) (tvar (varF y))
end
end
| tapp ef m ex =>
match teval n env ex with
| None => None
| Some None => Some None
| Some (Some vx) =>
match teval n env ef with
| None => None
| Some None => Some None
| Some (Some (vbool _)) => Some None
| Some (Some (vobj env2 f ds)) =>
match index m ds with
| None => Some None
| Some (dmem _) => Some None
| Some (dfld _) => Some None
| Some (dfun x ey) =>
teval n ((x,vx)::(f,vobj env2 f ds)::env2) ey
end
end
end
| tlet x ex ey =>
match teval n env ex with
| None => None
| Some None => Some None
| Some (Some vx) => teval n ((x,vx)::env) ey
end
end
end.
(* In dynamic subtyping, we generalize type selections from
x.T to t.T, i.e. from concrete variables x to t, where t
is any term that evaluates in the given G.
index x G = Some v becomes peval (tvar x) G v
The proofs require that G can be extended to G' without changing
the result of evaluation v. But if v is an object, the captured
environment will be G' instead of G. Therefore, we evaluate t
in a environment just large enough (tail (fresh_in_term t) G),
which is a sub environment of both G and G'.
Note that so far, this additional flexibility is not
exposed to the static type assignment / subtyping relations.
On the static side, it should be possible to use any reduction /
normalization relation or procedure that is consistent with teval.
For example:
- syntactic restriction to paths / field selections
- normalization of arbitrary terms if calculus is total
(see e.g. nano0-total.v)
- semantic restriction to total terms based on effect system
- arbitrary terms if we don't care if typing is decidable
*)
Definition peval (t:tm) (G:venv) r :=
fresh_in_term t <= fresh G /\
exists nm, forall n, n > nm ->
teval n (tail (fresh_in_term t) G) t = Some (Some r).
Definition MAX := 1.
Inductive stp2: nat -> bool -> venv -> ty -> venv -> ty -> list (id*(venv*ty)) -> nat -> Prop :=
| stp2_topx: forall m G1 G2 GH n1,
stp2 m true G1 TTop G2 TTop GH (S n1)
| stp2_botx: forall m G1 G2 GH n1,
stp2 m true G1 TBot G2 TBot GH (S n1)
| stp2_top: forall m G1 G2 GH T n1,
stp2 m true G1 T G1 T GH n1 -> (* regularity *)
stp2 m true G1 T G2 TTop GH (S n1)
| stp2_bot: forall m G1 G2 GH T n1,
stp2 m true G2 T G2 T GH n1 -> (* regularity *)
stp2 m true G1 TBot G2 T GH (S n1)
| stp2_bool: forall m G1 G2 GH n1,
stp2 m true G1 TBool G2 TBool GH (S n1)
| stp2_fld: forall G1 G2 l T2 T4 GH n1,
stp2 0 true G1 T2 G2 T4 GH n1 ->
stp2 0 true G1 (TFld l T2) G2 (TFld l T4) GH (S n1)
| stp2_fld2: forall m G1 G2 l T2 T4 GH n1,
stp2 (S m) false G1 T2 G2 T4 GH n1 ->
stp2 (S m) true G1 (TFld l T2) G2 (TFld l T4) GH (S n1)
| stp2_mem: forall G1 G2 l T1 T2 T3 T4 GH n1 n2,
stp2 0 false G2 T3 G1 T1 GH n1 ->
stp2 0 true G1 T2 G2 T4 GH n2 ->
stp2 0 true G1 (TMem l T1 T2) G2 (TMem l T3 T4) GH (S (n1+n2))
| stp2_mem2: forall m G1 G2 l T1 T2 T3 T4 GH n1 n2,
stp2 (S m) false G2 T3 G1 T1 GH n1 ->
stp2 (S m) false G1 T2 G2 T4 GH n2 ->
stp2 (S m) true G1 (TMem l T1 T2) G2 (TMem l T3 T4) GH (S (n1+n2))
(* strong version, with precise/invertible bounds *)
| stp2_strong_sel1: forall G1 G2 GX l f ds TX x T2 GH GX' TX' n1 n2,
peval x G1 (vobj GX f ds) ->
val_type GX' (vobj GX f ds) TX' 1 -> (* for downgrade *)
stp2 0 false GX' TX' G2 (TMem l TBot T2) GH n2 -> (* for downgrade *)
index l ds = Some (dmem TX) ->
closed 1 0 TX ->
stp2 0 true ((f, vobj GX f ds)::GX) (open (tvar (varF f)) TX) G2 T2 GH n1 ->
stp2 0 true G1 (TSel x l) G2 T2 GH (S (n1+n2))
| stp2_strong_sel2: forall G1 G2 GX l f ds TX x T1 GH GX' TX' n1 n2,
peval x G2 (vobj GX f ds) ->
val_type GX' (vobj GX f ds) TX' 1 -> (* for downgrade *)
stp2 0 false GX' TX' G1 (TMem l T1 TTop) GH n2 -> (* for downgrade *)
index l ds = Some (dmem TX) ->
closed 1 0 TX ->
stp2 0 false G1 T1 ((f, vobj GX f ds)::GX) (open (tvar (varF f)) TX) GH n1 ->
stp2 0 true G1 T1 G2 (TSel x l) GH (S (n1+n2))
(* existing object, but imprecise type *)
| stp2_sel1: forall m G1 G2 GX l TX x T2 GH n1 n2 v,
peval x G1 v ->
val_type GX v TX 1 ->
closed 0 0 TX ->
stp2 (S m) false GX TX G2 (TMem l TBot T2) GH n1 ->
stp2 (S m) true G2 T2 G2 T2 GH n2 -> (* regularity *)
stp2 (S m) true G1 (TSel x l) G2 T2 GH (S (n1+n2))
(*
| stp2_selb1: forall m G1 G2 GX l TX x x' T2 GH n1 n2 v nv,
index x G1 = Some v -> (index x' G2 = Some v \/ closed 0 0 T2) ->
val_type GX v TX nv ->
closed 0 0 TX ->
stp2 (S ( m)) false GX TX G2 (TBind (TMem l TBot T2)) [] n1 -> (* Note GH = [] *)
stp2 (S ( m)) true G2 (open (varF x') T2) G2 (open (varF x') T2) GH n2 -> (* regularity *)
stp2 (S ( m)) true G1 (TSel (varF x) l) G2 (open (varF x') T2) GH (S (n1+n2))
*)
| stp2_sel2: forall m G1 G2 GX l TX x T1 GH n1 n2 v,
peval x G2 v ->
val_type GX v TX 1 ->
closed 0 0 TX ->
stp2 (S m) false GX TX G1 (TMem l T1 TTop) GH n1 ->
stp2 (S m) true G1 T1 G1 T1 GH n2 -> (* regularity *)
stp2 (S m) true G1 T1 G2 (TSel x l) GH (S (n1+n2))
(*
| stp2_selb2: forall m G1 G2 GX l TX x x' T1 GH n1 n2 v nv,
index x G2 = Some v -> (index x' G1 = Some v \/ closed 0 0 T1) ->
val_type GX v TX nv ->
closed 0 0 TX ->
stp2 (S ( m)) false GX TX G1 (TBind (TMem l T1 TTop)) [] n1 -> (* Note GH = [] *)
stp2 (S ( m)) true G1 (open (varF x') T1) G1 (open (varF x') T1) GH n2 -> (* regularity *)
stp2 (S ( m)) true G1 (open (varF x') T1) G2 (TSel (varF x) l) GH (S (n1+n2))
*)
(* TODO: this is a simplif *)
| stp2_selxr: forall m G1 G2 l t x v GH n1,
path_head t = Some (varF x) ->
index x G1 = Some v ->
index x G2 = Some v ->
stp2 m true G1 (TSel t l) G2 (TSel t l) GH (S n1)
| stp2_selx: forall m G1 G2 l v x1 x2 GH n1,
peval x1 G1 v ->
peval x2 G2 v ->
stp2 m true G1 (TSel x1 l) G2 (TSel x2 l) GH (S n1)
(* hypothetical object *)
(*| stp2_sela1: forall m G1 G2 GX l TX x T2 GH n1 n2,
indexr x GH = Some (GX, TX) ->
closed 0 (S x) TX ->
stp2 (S m) false GX TX G2 (TMem l TBot T2) GH n1 ->
stp2 (S m) true G2 T2 G2 T2 GH n2 -> (* regularity *)
stp2 (S m) true G1 (TSel (varH x) l) G2 T2 GH (S (n1+n2))
*)
| stp2_sela1: forall m G1 G2 GX l TX x T2 GH GU GL n1 n2,
indexr x GH = Some (GX, TX) ->
closed 0 (S x) TX ->
length GL = (S x) ->
GH = GU ++ GL ->
stp2 (S m) false GX TX G2 (TMem l TBot T2) GL n1 ->
stp2 (S m) true G2 T2 G2 T2 GH n2 -> (* regularity *)
stp2 (S m) true G1 (TSel (tvar (varH x)) l) G2 T2 GH (S (n1+n2))
| stp2_sela2: forall m G1 G2 GX l TX x T1 GH GU GL n1 n2,
indexr x GH = Some (GX, TX) ->
closed 0 (S x) TX ->
length GL = (S x) ->
GH = GU ++ GL ->
stp2 (S m) false GX TX G1 (TMem l T1 TTop) GL n1 ->
stp2 (S m) true G1 T1 G1 T1 GH n2 -> (* regularity *)
stp2 (S m) true G1 T1 G2 (TSel (tvar (varH x)) l) GH (S (n1+n2))
| stp2_selab1: forall m G1 G2 GX l TX x T2 T2' GH GU GL n1 n2,
indexr x GH = Some (GX, TX) ->
closed 1 x T2 -> (* < x required in substitute *)
length GL = (S x) ->
GH = GU ++ GL ->
stp2 (S m) false GX TX G2 (TBind (TMem l TBot T2)) GL n1 ->
T2' = (open (tvar (varH x)) T2) ->
stp2 (S m) true G2 T2' G2 T2' GH n2 -> (* regularity *)
stp2 (S m) true G1 (TSel (tvar (varH x)) l) G2 T2' GH (S (n1+n2))
| stp2_selab2: forall m G1 G2 GX l TX x T1 T1' GH GU GL n1 n2,
indexr x GH = Some (GX, TX) ->
closed 1 x T1 -> (* < x required in substitute *)
length GL = (S x) ->
GH = GU ++ GL ->
stp2 (S m) false GX TX G1 (TBind (TMem l T1 TTop)) GL n1 ->
T1' = (open (tvar (varH x)) T1) ->
stp2 (S m) true G1 T1' G1 T1' GH n2 -> (* regularity *)
stp2 (S m) true G1 T1' G2 (TSel (tvar (varH x)) l) GH (S (n1+n2))
| stp2_selax: forall m G1 G2 GX l TX x GH n1,
indexr x GH = Some (GX, TX) ->
stp2 (S m) true G1 (TSel (tvar (varH x)) l) G2 (TSel (tvar (varH x)) l) GH (S n1)
| stp2_all: forall m G1 G2 l T1 T2 T3 T4 GH n1 n1' n2,
stp2 1 false G2 T3 G1 T1 GH n1 ->
closed 1 (length GH) T2 -> (* must not accidentally bind x *)
closed 1 (length GH) T4 ->
stp2 1 false G1 (open (tvar (varH (length GH))) T2) G1 (open (tvar (varH (length GH))) T2) ((0,(G1, T1))::GH) n1' -> (* regularity *)
stp2 1 false G1 (open (tvar (varH (length GH))) T2) G2 (open (tvar (varH (length GH))) T4) ((0,(G2, T3))::GH) n2 ->
stp2 m true G1 (TAll l T1 T2) G2 (TAll l T3 T4) GH (S (n1+n1'+n2))
| stp2_bind: forall m G1 G2 T1 T2 GH n1 n2,
closed 1 (length GH) T1 -> (* must not accidentally bind x *)
closed 1 (length GH) T2 ->
stp2 1 false G2 (open (tvar (varH (length GH))) T2) G2 (open (tvar (varH (length GH))) T2) ((0,(G2, open (tvar (varH (length GH))) T2))::GH) n2 -> (* regularity *)
stp2 1 false G1 (open (tvar (varH (length GH))) T1) G2 (open (tvar (varH (length GH))) T2) ((0,(G1, open (tvar (varH (length GH))) T1))::GH) n1 ->
stp2 m true G1 (TBind T1) G2 (TBind T2) GH (S (n1+n2))
| stp2_bind1: forall m G1 G2 T1 T2 GH n1 n2,
closed 1 (length GH) T1 -> (* must not accidentally bind x *)
closed 0 (length GH) T2 ->
stp2 m false G2 T2 G2 T2 GH n2 -> (* regularity *)
stp2 1 false G1 (open (tvar (varH (length GH))) T1) G2 T2 ((0,(G1, open (tvar (varH (length GH))) T1))::GH) n1 ->
stp2 m true G1 (TBind T1) G2 T2 GH (S (n1+n2))
| stp2_and11: forall m n1 n2 G1 G2 GH T1 T2 T,
stp2 m true G1 T1 G2 T GH n1 ->
stp2 m true G1 T2 G1 T2 GH n2 -> (* regularity *)
stp2 m true G1 (TAnd T1 T2) G2 T GH (S (n1+n2))
| stp2_and12: forall m n1 n2 G1 G2 GH T1 T2 T,
stp2 m true G1 T2 G2 T GH n1 ->
stp2 m true G1 T1 G1 T1 GH n2 -> (* regularity *)
stp2 m true G1 (TAnd T1 T2) G2 T GH (S (n1+n2))
| stp2_and2: forall m n1 n2 G1 G2 GH T1 T2 T,
stp2 m false G1 T G2 T1 GH n1 ->
stp2 m false G1 T G2 T2 GH n2 ->
stp2 m true G1 T G2 (TAnd T1 T2) GH (S (n1+n2))
| stp2_or21: forall m n1 n2 G1 G2 GH T1 T2 T,
stp2 m false G1 T G2 T1 GH n1 ->
stp2 m true G2 T2 G2 T2 GH n2 -> (* regularity *)
stp2 m true G1 T G2 (TOr T1 T2) GH (S (n1+n2))
| stp2_or22: forall m n1 n2 G1 G2 GH T1 T2 T,
stp2 m false G1 T G2 T2 GH n1 ->
stp2 m true G2 T1 G2 T1 GH n2 -> (* regularity *)
stp2 m true G1 T G2 (TOr T1 T2) GH (S (n1+n2))
| stp2_or1: forall m n1 n2 G1 G2 GH T1 T2 T,
stp2 m true G1 T1 G2 T GH n1 ->
stp2 m true G1 T2 G2 T GH n2 ->
stp2 m true G1 (TOr T1 T2) G2 T GH (S (n1+n2))
| stp2_wrapf: forall m G1 G2 T1 T2 GH n1,
stp2 m true G1 T1 G2 T2 GH n1 ->
stp2 m false G1 T1 G2 T2 GH (S n1)
| stp2_transf: forall m G1 G2 G3 T1 T2 T3 GH n1 n2,
stp2 m true G1 T1 G2 T2 GH n1 ->
stp2 m false G2 T2 G3 T3 GH n2 ->
stp2 m false G1 T1 G3 T3 GH (S (n1+n2))
with wf_env : venv -> tenv -> Prop :=
| wfe_nil : wf_env nil nil
| wfe_cons : forall n v t vs ts nv,
val_type ((n,v)::vs) v t nv ->
wf_env vs ts ->
wf_env (cons (n,v) vs) (cons (n,t) ts)
with val_type : venv -> vl -> ty -> nat -> Prop :=
| v_bool: forall venv b TE,
(exists n, stp2 0 true [] TBool venv TE [] n) ->
val_type venv (vbool b) TE 1
| v_obj: forall env venv tenv f ds T TX TE,
wf_env venv tenv ->
open (tvar (varF f)) T = TX ->
dcs_has_type ((f,TX)::tenv) f ds T ->
fresh venv = f ->
(exists n, stp2 0 true ((f, vobj venv f ds)::venv) TX env TE [] n)->
val_type env (vobj venv f ds) TE 1
| v_pack: forall venv venv3 x v T T2 T3 n,
peval x venv v ->
val_type venv v T n ->
open x T2 = T ->
(exists n, stp2 0 true venv (TBind T2) venv3 T3 [] n) ->
val_type venv3 v T3 (S n)
.
Inductive wf_envh : venv -> aenv -> tenv -> Prop :=
| wfeh_nil : forall vvs, wf_envh vvs nil nil
| wfeh_cons : forall n t vs vvs ts,
wf_envh vvs vs ts ->
wf_envh vvs (cons (n,(vvs,t)) vs) (cons (n,t) ts)
.
Inductive valh_type : venv -> aenv -> (venv*ty) -> ty -> Prop :=
| v_tya: forall aenv venv T1,
valh_type venv aenv (venv, T1) T1
.
Definition stpd2 b G1 T1 G2 T2 GH := exists n, stp2 MAX b G1 T1 G2 T2 GH n.
Definition sstpd2 b G1 T1 G2 T2 GH := exists n, stp2 0 b G1 T1 G2 T2 GH n.
Definition valtpd G v T := exists n, val_type G v T n.
Ltac ep := match goal with
| [ |- stp2 ?M1 ?M2 ?G1 ?T1 ?G2 ?T2 ?GH ?N ] => assert (exists (x:nat), stp2 M1 M2 G1 T1 G2 T2 GH x) as EEX
end.
Ltac eu := match goal with
| H: pevald1 _ _ _ |- _ => destruct H as [? H]
| H: stpd _ _ _ _ |- _ => destruct H as [? H]
| H: stpd2 _ _ _ _ _ _ |- _ => destruct H as [? H]
| H: sstpd2 _ _ _ _ _ _ |- _ => destruct H as [? H]
(* | H: exists n: nat , _ |- _ =>
destruct H as [e P] *)
end.
Hint Constructors stp2.
Hint Unfold stpd2.
Lemma stpd2_topx: forall G1 G2 GH,
stpd2 true G1 TTop G2 TTop GH.
Proof. intros. repeat exists (S 0). eauto. Qed.
Lemma stpd2_botx: forall G1 G2 GH,
stpd2 true G1 TBot G2 TBot GH.
Proof. intros. repeat exists (S 0). eauto. Qed.
Lemma stpd2_top: forall G1 G2 GH T,
stpd2 true G1 T G1 T GH ->
stpd2 true G1 T G2 TTop GH.
Proof. intros. repeat eu. eauto. Qed.
Lemma stpd2_bot: forall G1 G2 GH T,
stpd2 true G2 T G2 T GH ->
stpd2 true G1 TBot G2 T GH.
Proof. intros. repeat eu. eauto. Qed.
Lemma stpd2_bool: forall G1 G2 GH,
stpd2 true G1 TBool G2 TBool GH.
Proof. intros. repeat exists (S 0). eauto. Qed.
Lemma stpd2_fld: forall G1 G2 GH l T12 T22,
stpd2 false G1 T12 G2 T22 GH ->
stpd2 true G1 (TFld l T12) G2 (TFld l T22) GH.
Proof. intros. repeat eu. eauto. unfold stpd2. eexists. eapply stp2_fld2; eauto. Qed.
Lemma stpd2_mem: forall G1 G2 GH l T11 T12 T21 T22,
stpd2 false G2 T21 G1 T11 GH ->
stpd2 false G1 T12 G2 T22 GH ->
stpd2 true G1 (TMem l T11 T12) G2 (TMem l T21 T22) GH.
Proof. intros. repeat eu. eauto. unfold stpd2. eexists. eapply stp2_mem2; eauto. Qed.
Lemma stpd2_sel1: forall G1 G2 GX l TX x T2 GH v,
peval x G1 v ->
val_type GX v TX 1 ->
closed 0 0 TX ->
stpd2 false GX TX G2 (TMem l TBot T2) GH ->
stpd2 true G2 T2 G2 T2 GH ->
stpd2 true G1 (TSel x l) G2 T2 GH.
Proof. intros. repeat eu. eexists. eapply stp2_sel1; eauto. Qed.
(*
Lemma stpd2_selb1: forall G1 G2 GX l TX x x' T2 GH v nv,
index x G1 = Some v -> (index x' G2 = Some v \/ closed 0 0 T2) ->
val_type GX v TX nv ->
closed 0 0 TX ->
stpd2 false GX TX G2 (TBind (TMem l TBot T2)) [] -> (* Note GH = [] *)
stpd2 true G2 (open (varF x') T2) G2 (open (varF x') T2) GH ->
stpd2 true G1 (TSel (varF x) l) G2 (open (varF x') T2) GH.