Theory HOL-Library.Predicate_Compile_Alternative_Defs

(*  Title:      HOL/Library/Predicate_Compile_Alternative_Defs.thy
    Author:     Lukas Bulwahn, TU Muenchen
*)

theory Predicate_Compile_Alternative_Defs
  imports Main
begin

section ‹Common constants›

declare HOL.if_bool_eq_disj[code_pred_inline]

declare bool_diff_def[code_pred_inline]
declare inf_bool_def[abs_def, code_pred_inline]
declare less_bool_def[abs_def, code_pred_inline]
declare le_bool_def[abs_def, code_pred_inline]

lemma min_bool_eq [code_pred_inline]: "(min :: bool => bool => bool) == (∧)"
by (rule eq_reflection) (auto simp add: fun_eq_iff min_def)

lemma [code_pred_inline]: 
  "((A::bool) ≠ (B::bool)) = ((A ∧ ¬ B) ∨ (B ∧ ¬ A))"
by fast

setup ‹Predicate_Compile_Data.ignore_consts [\<^const_name>‹Let›]›

section ‹Pairs›

setup ‹Predicate_Compile_Data.ignore_consts [\<^const_name>‹fst›, \<^const_name>‹snd›, \<^const_name>‹case_prod›]›

section ‹Filters›

(*TODO: shouldn't this be done by typedef? *)
setup ‹Predicate_Compile_Data.ignore_consts [\<^const_name>‹Abs_filter›, \<^const_name>‹Rep_filter›]›

section ‹Bounded quantifiers›

declare Ball_def[code_pred_inline]
declare Bex_def[code_pred_inline]

section ‹Operations on Predicates›

lemma Diff[code_pred_inline]:
  "(A - B) = (%x. A x ∧ ¬ B x)"
  by (simp add: fun_eq_iff)

lemma subset_eq[code_pred_inline]:
  "(P :: 'a ⇒ bool) < (Q :: 'a ⇒ bool) ≡ ((∃x. Q x ∧ (¬ P x)) ∧ (∀x. P x ⟶ Q x))"
  by (rule eq_reflection) (auto simp add: less_fun_def le_fun_def)

lemma set_equality[code_pred_inline]:
  "A = B ⟷ (∀x. A x ⟶ B x) ∧ (∀x. B x ⟶ A x)"
  by (auto simp add: fun_eq_iff)

section ‹Setup for Numerals›

setup ‹Predicate_Compile_Data.ignore_consts [\<^const_name>‹numeral›]›
setup ‹Predicate_Compile_Data.keep_functions [\<^const_name>‹numeral›]›
setup ‹Predicate_Compile_Data.ignore_consts [\<^const_name>‹Char›]›
setup ‹Predicate_Compile_Data.keep_functions [\<^const_name>‹Char›]›

setup ‹Predicate_Compile_Data.ignore_consts [\<^const_name>‹divide›, \<^const_name>‹modulo›, \<^const_name>‹times›]›

section ‹Arithmetic operations›

subsection ‹Arithmetic on naturals and integers›

definition plus_eq_nat :: "nat => nat => nat => bool"
where
  "plus_eq_nat x y z = (x + y = z)"

definition minus_eq_nat :: "nat => nat => nat => bool"
where
  "minus_eq_nat x y z = (x - y = z)"

definition plus_eq_int :: "int => int => int => bool"
where
  "plus_eq_int x y z = (x + y = z)"

definition minus_eq_int :: "int => int => int => bool"
where
  "minus_eq_int x y z = (x - y = z)"

definition subtract
where
  [code_unfold]: "subtract x y = y - x"

setup ‹
let
  val Fun = Predicate_Compile_Aux.Fun
  val Input = Predicate_Compile_Aux.Input
  val Output = Predicate_Compile_Aux.Output
  val Bool = Predicate_Compile_Aux.Bool
  val iio = Fun (Input, Fun (Input, Fun (Output, Bool)))
  val ioi = Fun (Input, Fun (Output, Fun (Input, Bool)))
  val oii = Fun (Output, Fun (Input, Fun (Input, Bool)))
  val ooi = Fun (Output, Fun (Output, Fun (Input, Bool)))
  val plus_nat = Core_Data.functional_compilation \<^const_name>‹plus› iio
  val minus_nat = Core_Data.functional_compilation \<^const_name>‹minus› iio
  fun subtract_nat compfuns (_ : typ) =
    let
      val T = Predicate_Compile_Aux.mk_monadT compfuns \<^typ>‹nat›
    in
      absdummy \<^typ>‹nat› (absdummy \<^typ>‹nat›
        (Const (\<^const_name>‹If›, \<^typ>‹bool› --> T --> T --> T) $
          (\<^term>‹(>) :: nat => nat => bool› $ Bound 1 $ Bound 0) $
          Predicate_Compile_Aux.mk_empty compfuns \<^typ>‹nat› $
          Predicate_Compile_Aux.mk_single compfuns
          (\<^term>‹(-) :: nat => nat => nat› $ Bound 0 $ Bound 1)))
    end
  fun enumerate_addups_nat compfuns (_ : typ) =
    absdummy \<^typ>‹nat› (Predicate_Compile_Aux.mk_iterate_upto compfuns \<^typ>‹nat * nat›
    (absdummy \<^typ>‹natural› (\<^term>‹Pair :: nat => nat => nat * nat› $
      (\<^term>‹nat_of_natural› $ Bound 0) $
      (\<^term>‹(-) :: nat => nat => nat› $ Bound 1 $ (\<^term>‹nat_of_natural› $ Bound 0))),
      \<^term>‹0 :: natural›, \<^term>‹natural_of_nat› $ Bound 0))
  fun enumerate_nats compfuns  (_ : typ) =
    let
      val (single_const, _) = strip_comb (Predicate_Compile_Aux.mk_single compfuns \<^term>‹0 :: nat›)
      val T = Predicate_Compile_Aux.mk_monadT compfuns \<^typ>‹nat›
    in
      absdummy \<^typ>‹nat› (absdummy \<^typ>‹nat›
        (Const (\<^const_name>‹If›, \<^typ>‹bool› --> T --> T --> T) $
          (\<^term>‹(=) :: nat => nat => bool› $ Bound 0 $ \<^term>‹0::nat›) $
          (Predicate_Compile_Aux.mk_iterate_upto compfuns \<^typ>‹nat› (\<^term>‹nat_of_natural›,
            \<^term>‹0::natural›, \<^term>‹natural_of_nat› $ Bound 1)) $
            (single_const $ (\<^term>‹(+) :: nat => nat => nat› $ Bound 1 $ Bound 0))))
    end
in
  Core_Data.force_modes_and_compilations \<^const_name>‹plus_eq_nat›
    [(iio, (plus_nat, false)), (oii, (subtract_nat, false)), (ioi, (subtract_nat, false)),
     (ooi, (enumerate_addups_nat, false))]
  #> Predicate_Compile_Fun.add_function_predicate_translation
       (\<^term>‹plus :: nat => nat => nat›, \<^term>‹plus_eq_nat›)
  #> Core_Data.force_modes_and_compilations \<^const_name>‹minus_eq_nat›
       [(iio, (minus_nat, false)), (oii, (enumerate_nats, false))]
  #> Predicate_Compile_Fun.add_function_predicate_translation
      (\<^term>‹minus :: nat => nat => nat›, \<^term>‹minus_eq_nat›)
  #> Core_Data.force_modes_and_functions \<^const_name>‹plus_eq_int›
    [(iio, (\<^const_name>‹plus›, false)), (ioi, (\<^const_name>‹subtract›, false)),
     (oii, (\<^const_name>‹subtract›, false))]
  #> Predicate_Compile_Fun.add_function_predicate_translation
       (\<^term>‹plus :: int => int => int›, \<^term>‹plus_eq_int›)
  #> Core_Data.force_modes_and_functions \<^const_name>‹minus_eq_int›
    [(iio, (\<^const_name>‹minus›, false)), (oii, (\<^const_name>‹plus›, false)),
     (ioi, (\<^const_name>‹minus›, false))]
  #> Predicate_Compile_Fun.add_function_predicate_translation
      (\<^term>‹minus :: int => int => int›, \<^term>‹minus_eq_int›)
end
›

subsection ‹Inductive definitions for ordering on naturals›

inductive less_nat
where
  "less_nat 0 (Suc y)"
| "less_nat x y ==> less_nat (Suc x) (Suc y)"

lemma less_nat[code_pred_inline]:
  "x < y = less_nat x y"
apply (rule iffI)
apply (induct x arbitrary: y)
apply (case_tac y) apply (auto intro: less_nat.intros)
apply (case_tac y)
apply (auto intro: less_nat.intros)
apply (induct rule: less_nat.induct)
apply auto
done

inductive less_eq_nat
where
  "less_eq_nat 0 y"
| "less_eq_nat x y ==> less_eq_nat (Suc x) (Suc y)"

lemma [code_pred_inline]:
"x <= y = less_eq_nat x y"
apply (rule iffI)
apply (induct x arbitrary: y)
apply (auto intro: less_eq_nat.intros)
apply (case_tac y) apply (auto intro: less_eq_nat.intros)
apply (induct rule: less_eq_nat.induct)
apply auto done

section ‹Alternative list definitions›

subsection ‹Alternative rules for ‹length››

definition size_list' :: "'a list => nat"
where "size_list' = size"

lemma size_list'_simps:
  "size_list' [] = 0"
  "size_list' (x # xs) = Suc (size_list' xs)"
by (auto simp add: size_list'_def)

declare size_list'_simps[code_pred_def]
declare size_list'_def[symmetric, code_pred_inline]


subsection ‹Alternative rules for ‹list_all2››

lemma list_all2_NilI [code_pred_intro]: "list_all2 P [] []"
by auto

lemma list_all2_ConsI [code_pred_intro]: "list_all2 P xs ys ==> P x y ==> list_all2 P (x#xs) (y#ys)"
by auto

code_pred [skip_proof] list_all2
proof -
  case list_all2
  from this show thesis
    apply -
    apply (case_tac xb)
    apply (case_tac xc)
    apply auto
    apply (case_tac xc)
    apply auto
    done
qed

subsection ‹Alternative rules for membership in lists›

declare in_set_member[code_pred_inline]

lemma member_intros [code_pred_intro]:
  "List.member (x#xs) x"
  "List.member xs x ⟹ List.member (y#xs) x"
by(simp_all add: List.member_def)

code_pred List.member
  by(auto simp add: List.member_def elim: list.set_cases)

code_identifier constant member_i_i
   ⇀ (SML) "List.member_i_i"
  and (OCaml) "List.member_i_i"
  and (Haskell) "List.member_i_i"
  and (Scala) "List.member_i_i"

code_identifier constant member_i_o
   ⇀ (SML) "List.member_i_o"
  and (OCaml) "List.member_i_o"
  and (Haskell) "List.member_i_o"
  and (Scala) "List.member_i_o"

section ‹Setup for String.literal›

setup ‹Predicate_Compile_Data.ignore_consts [\<^const_name>‹String.Literal›]›

section ‹Simplification rules for optimisation›

lemma [code_pred_simp]: "¬ False == True"
by auto

lemma [code_pred_simp]: "¬ True == False"
by auto

lemma less_nat_k_0 [code_pred_simp]: "less_nat k 0 == False"
unfolding less_nat[symmetric] by auto

end