theory ExPS8

imports "Parser"

begin

(* example 8 from Peter Sewell's bestiary *)

atom_decl name

(* One function is recursive and the other one is not,

   and as the parser cannot handle this we cannot set

   the reference.  *)

ML {* val _ = recursive := false  *}

nominal_datatype exp8 =

  EVar name

| EUnit

| EPair exp8 exp8

| ELetRec l::lrbs8 e::exp8 bind "b_lrbs8 l" in e (* rec *)

and fnclause =

  K x::name p::pat8 f::exp8 bind "b_pat p" in f (* non-rec *)

and fnclauses =

  S fnclause

| ORs fnclause fnclauses

and lrb8 =

  Clause fnclauses

and lrbs8 =

  Single lrb8

| More lrb8 lrbs8

and pat8 =

  PVar name

| PUnit

| PPair pat8 pat8

binder

  b_lrbs8 :: "lrbs8 \<Rightarrow> atom set" and

  b_pat :: "pat8 \<Rightarrow> atom set" and

  b_fnclauses :: "fnclauses \<Rightarrow> atom set" and

  b_fnclause :: "fnclause \<Rightarrow> atom set" and

  b_lrb8 :: "lrb8 \<Rightarrow> atom set"

where

  "b_lrbs8 (Single l) = b_lrb8 l"

| "b_lrbs8 (More l ls) = b_lrb8 l \<union> b_lrbs8 ls"

| "b_pat (PVar x) = {atom x}"

| "b_pat (PUnit) = {}"

| "b_pat (PPair p1 p2) = b_pat p1 \<union> b_pat p2"

| "b_fnclauses (S fc) = (b_fnclause fc)"

| "b_fnclauses (ORs fc fcs) = (b_fnclause fc) \<union> (b_fnclauses fcs)"

| "b_lrb8 (Clause fcs) = (b_fnclauses fcs)"

| "b_fnclause (K x pat exp8) = {atom x}"

thm exp7_lrb_lrbs.eq_iff

thm exp7_lrb_lrbs.supp

end