theory Terms
imports Nominal "../QuotMain" "../QuotList"
begin

atom_decl name

text {* primrec seems to be genarally faster than fun *}

section {*** lets with binding patterns ***}

datatype trm1 =
  Vr1 "name"
| Ap1 "trm1" "trm1"
| Lm1 "name" "trm1"        --"name is bound in trm1"
| Lt1 "bp" "trm1" "trm1"   --"all variables in bp are bound in the 2nd trm1"
and bp =
  BUnit
| BVr "name"
| BPr "bp" "bp"

(* to be given by the user *)
primrec 
  bv1
where
  "bv1 (BUnit) = {}"
| "bv1 (BVr x) = {x}"
| "bv1 (BPr bp1 bp2) = (bv1 bp1) \<union> (bv1 bp1)"

(* needs to be calculated by the package *)
primrec 
  fv_trm1 and fv_bp
where
  "fv_trm1 (Vr1 x) = {x}"
| "fv_trm1 (Ap1 t1 t2) = (fv_trm1 t1) \<union> (fv_trm1 t2)"
| "fv_trm1 (Lm1 x t) = (fv_trm1 t) - {x}"
| "fv_trm1 (Lt1 bp t1 t2) = (fv_trm1 t1) \<union> (fv_trm1 t2 - bv1 bp)"
| "fv_bp (BUnit) = {}"
| "fv_bp (BVr x) = {x}"
| "fv_bp (BPr b1 b2) = (fv_bp b1) \<union> (fv_bp b2)"

(* needs to be stated by the package *)
overloading
  perm_trm1 \<equiv> "perm :: 'x prm \<Rightarrow> trm1 \<Rightarrow> trm1"   (unchecked)
  perm_bp \<equiv> "perm :: 'x prm \<Rightarrow> bp \<Rightarrow> bp" (unchecked)
begin

primrec
  perm_trm1 and perm_bp
where
  "perm_trm1 pi (Vr1 a) = Vr1 (pi \<bullet> a)"
| "perm_trm1 pi (Ap1 t1 t2) = Ap1 (perm_trm1 pi t1) (perm_trm1 pi t2)"
| "perm_trm1 pi (Lm1 a t) = Lm1 (pi \<bullet> a) (perm_trm1 pi t)"
| "perm_trm1 pi (Lt1 bp t1 t2) = Lt1 (perm_bp pi bp) (perm_trm1 pi t1) (perm_trm1 pi t2)"
| "perm_bp pi (BUnit) = BUnit"
| "perm_bp pi (BVr a) = BVr (pi \<bullet> a)"
| "perm_bp pi (BPr bp1 bp2) = BPr (perm_bp pi bp1) (perm_bp pi bp2)"

end

inductive
  alpha1 :: "trm1 \<Rightarrow> trm1 \<Rightarrow> bool" ("_ \<approx>1 _" [100, 100] 100)
where
  a1: "a = b \<Longrightarrow> (Vr1 a) \<approx>1 (Vr1 b)"
| a2: "\<lbrakk>t1 \<approx>1 t2; s1 \<approx>1 s2\<rbrakk> \<Longrightarrow> Ap1 t1 s1 \<approx>1 Ap1 t2 s2"
| a3: "\<exists>pi::name prm. (fv_trm1 t - {a} = fv_trm1 s - {b} \<and> (fv_trm1 t - {a})\<sharp>* pi \<and> (pi \<bullet> t) \<approx>1 s \<and> (pi \<bullet> a) = b)
       \<Longrightarrow> Lm1 a t \<approx>1 Lm1 b s"
| a4: "\<exists>pi::name prm.(
         t1 \<approx>1 t2 \<and>
         (fv_trm1 s1 - fv_bp b1 = fv_trm1 s2 - fv_bp b2) \<and>
         (fv_trm1 s1 - fv_bp b1) \<sharp>* pi \<and>
         (pi \<bullet> s1 = s2)                    (* Optional: \<and> (pi \<bullet> b1 = b2) *)
       ) \<Longrightarrow> Lt1 b1 t1 s1 \<approx>1 Lt1 b2 t2 s2"

lemma alpha1_equivp: "equivp alpha1" sorry

quotient_type qtrm1 = trm1 / alpha1
  by (rule alpha1_equivp)


section {*** lets with single assignments ***}

datatype trm2 =
  Vr2 "name"
| Ap2 "trm2" "trm2"
| Lm2 "name" "trm2"
| Lt2 "assign" "trm2"
and assign =
  As "name" "trm2"

(* to be given by the user *)
primrec 
  bv2
where
  "bv2 (As x t) = {x}"

(* needs to be calculated by the package *)
primrec
  fv_trm2 and fv_assign
where
  "fv_trm2 (Vr2 x) = {x}"
| "fv_trm2 (Ap2 t1 t2) = (fv_trm2 t1) \<union> (fv_trm2 t2)"
| "fv_trm2 (Lm2 x t) = (fv_trm2 t) - {x}"
| "fv_trm2 (Lt2 as t) = (fv_trm2 t - bv2 as) \<union> (fv_assign as)"
| "fv_assign (As x t) = (fv_trm2 t)"

(* needs to be stated by the package *)
overloading
  perm_trm2 \<equiv> "perm :: 'x prm \<Rightarrow> trm2 \<Rightarrow> trm2"   (unchecked)
  perm_assign \<equiv> "perm :: 'x prm \<Rightarrow> assign \<Rightarrow> assign" (unchecked)
begin

primrec
  perm_trm2 and perm_assign
where
  "perm_trm2 pi (Vr2 a) = Vr2 (pi \<bullet> a)"
| "perm_trm2 pi (Ap2 t1 t2) = Ap2 (perm_trm2 pi t1) (perm_trm2 pi t2)"
| "perm_trm2 pi (Lm2 a t) = Lm2 (pi \<bullet> a) (perm_trm2 pi t)"
| "perm_trm2 pi (Lt2 as t) = Lt2 (perm_assign pi as) (perm_trm2 pi t)"
| "perm_assign pi (As a t) = As (pi \<bullet> a) (perm_trm2 pi t)"

end

inductive
  alpha2 :: "trm2 \<Rightarrow> trm2 \<Rightarrow> bool" ("_ \<approx>2 _" [100, 100] 100)
where
  a1: "a = b \<Longrightarrow> (Vr2 a) \<approx>2 (Vr2 b)"
| a2: "\<lbrakk>t1 \<approx>2 t2; s1 \<approx>2 s2\<rbrakk> \<Longrightarrow> Ap2 t1 s1 \<approx>2 Ap2 t2 s2"
| a3: "\<exists>pi::name prm. (fv_trm2 t - {a} = fv_trm2 s - {b} \<and> (fv_trm2 t - {a})\<sharp>* pi \<and> (pi \<bullet> t) \<approx>2 s \<and> (pi \<bullet> a) = b)
       \<Longrightarrow> Lm2 a t \<approx>2 Lm2 b s"
| a4: "\<exists>pi::name prm. (
         fv_trm2 t1 - fv_assign b1 = fv_trm2 t2 - fv_assign b2 \<and>
         (fv_trm2 t1 - fv_assign b1) \<sharp>* pi \<and>
         pi \<bullet> t1 = t2       (* \<and> (pi \<bullet> b1 = b2) *)
       ) \<Longrightarrow> Lt2 b1 t1 \<approx>2 Lt2 b2 t2"

lemma alpha2_equivp: "equivp alpha2" sorry

quotient_type qtrm2 = trm2 / alpha2
  by (rule alpha2_equivp)

section {*** lets with many assignments ***}

datatype trm3 =
  Vr3 "name"
| Ap3 "trm3" "trm3"
| Lm3 "name" "trm3"
| Lt3 "assigns" "trm3"
and assigns =
  ANil
| ACons "name" "trm3" "assigns"

(* to be given by the user *)
primrec 
  bv3
where
  "bv3 ANil = {}"
| "bv3 (ACons x t as) = {x} \<union> (bv3 as)"

primrec
  fv_trm3 and fv_assigns
where
  "fv_trm3 (Vr3 x) = {x}"
| "fv_trm3 (Ap3 t1 t2) = (fv_trm3 t1) \<union> (fv_trm3 t2)"
| "fv_trm3 (Lm3 x t) = (fv_trm3 t) - {x}"
| "fv_trm3 (Lt3 as t) = (fv_trm3 t - bv3 as) \<union> (fv_assigns as)"
| "fv_assigns (ANil) = {}"
| "fv_assigns (ACons x t as) = (fv_trm3 t) \<union> (fv_assigns as)"

(* needs to be stated by the package *)
overloading
  perm_trm3 \<equiv> "perm :: 'x prm \<Rightarrow> trm3 \<Rightarrow> trm3"   (unchecked)
  perm_assigns \<equiv> "perm :: 'x prm \<Rightarrow> assigns \<Rightarrow> assigns" (unchecked)
begin

primrec
  perm_trm3 and perm_assigns
where
  "perm_trm3 pi (Vr3 a) = Vr3 (pi \<bullet> a)"
| "perm_trm3 pi (Ap3 t1 t2) = Ap3 (perm_trm3 pi t1) (perm_trm3 pi t2)"
| "perm_trm3 pi (Lm3 a t) = Lm3 (pi \<bullet> a) (perm_trm3 pi t)"
| "perm_trm3 pi (Lt3 as t) = Lt3 (perm_assigns pi as) (perm_trm3 pi t)"
| "perm_assigns pi (ANil) = ANil"
| "perm_assigns pi (ACons a t as) = ACons (pi \<bullet> a) (perm_trm3 pi t) (perm_assigns pi as)"

end

inductive
  alpha3 :: "trm3 \<Rightarrow> trm3 \<Rightarrow> bool" ("_ \<approx>3 _" [100, 100] 100)
where
  a1: "a = b \<Longrightarrow> (Vr3 a) \<approx>3 (Vr3 b)"
| a2: "\<lbrakk>t1 \<approx>3 t2; s1 \<approx>3 s2\<rbrakk> \<Longrightarrow> Ap3 t1 s1 \<approx>3 Ap3 t2 s2"
| a3: "\<exists>pi::name prm. (fv_trm3 t - {a} = fv_trm3 s - {b} \<and> (fv_trm3 t - {a})\<sharp>* pi \<and> (pi \<bullet> t) \<approx>3 s \<and> (pi \<bullet> a) = b)
       \<Longrightarrow> Lm3 a t \<approx>3 Lm3 b s"
| a4: "\<exists>pi::name prm. (
         fv_trm3 t1 - fv_assigns b1 = fv_trm3 t2 - fv_assigns b2 \<and>
         (fv_trm3 t1 - fv_assigns b1) \<sharp>* pi \<and>
         pi \<bullet> t1 = t2      (* \<and> (pi \<bullet> b1 = b2)  *)
       ) \<Longrightarrow> Lt3 b1 t1 \<approx>3 Lt3 b2 t2"

lemma alpha3_equivp: "equivp alpha3" sorry

quotient_type qtrm3 = trm3 / alpha3
  by (rule alpha3_equivp)

end
