Theory Finite_Map

(*  Title:      HOL/Library/Finite_Map.thy
    Author:     Lars Hupel, TU München
*)

section ‹Type of finite maps defined as a subtype of maps›

theory Finite_Map
  imports FSet AList Conditional_Parametricity
  abbrevs "(=" = "⊆⇩f"
begin

subsection ‹Auxiliary constants and lemmas over @{type map}›

parametric_constant map_add_transfer[transfer_rule]: map_add_def
parametric_constant map_of_transfer[transfer_rule]: map_of_def

context includes lifting_syntax begin

abbreviation rel_map :: "('b ⇒ 'c ⇒ bool) ⇒ ('a ⇀ 'b) ⇒ ('a ⇀ 'c) ⇒ bool" where
"rel_map f ≡ (=) ===> rel_option f"

lemma ran_transfer[transfer_rule]: "(rel_map A ===> rel_set A) ran ran"
proof
  fix m n
  assume "rel_map A m n"
  show "rel_set A (ran m) (ran n)"
    proof (rule rel_setI)
      fix x
      assume "x ∈ ran m"
      then obtain a where "m a = Some x"
        unfolding ran_def by auto

      have "rel_option A (m a) (n a)"
        using ‹rel_map A m n›
        by (auto dest: rel_funD)
      then obtain y where "n a = Some y" "A x y"
        unfolding ‹m a = _›
        by cases auto
      then show "∃y ∈ ran n. A x y"
        unfolding ran_def by blast
    next
      fix y
      assume "y ∈ ran n"
      then obtain a where "n a = Some y"
        unfolding ran_def by auto

      have "rel_option A (m a) (n a)"
        using ‹rel_map A m n›
        by (auto dest: rel_funD)
      then obtain x where "m a = Some x" "A x y"
        unfolding ‹n a = _›
        by cases auto
      then show "∃x ∈ ran m. A x y"
        unfolding ran_def by blast
    qed
qed

lemma ran_alt_def: "ran m = (the ∘ m) ` dom m"
unfolding ran_def dom_def by force

parametric_constant dom_transfer[transfer_rule]: dom_def

definition map_upd :: "'a ⇒ 'b ⇒ ('a ⇀ 'b) ⇒ ('a ⇀ 'b)" where
"map_upd k v m = m(k ↦ v)"

parametric_constant map_upd_transfer[transfer_rule]: map_upd_def

definition map_filter :: "('a ⇒ bool) ⇒ ('a ⇀ 'b) ⇒ ('a ⇀ 'b)" where
"map_filter P m = (λx. if P x then m x else None)"

parametric_constant map_filter_transfer[transfer_rule]: map_filter_def

lemma map_filter_map_of[simp]: "map_filter P (map_of m) = map_of [(k, _) ← m. P k]"
proof
  fix x
  show "map_filter P (map_of m) x = map_of [(k, _) ← m. P k] x"
    by (induct m) (auto simp: map_filter_def)
qed

lemma map_filter_finite[intro]:
  assumes "finite (dom m)"
  shows "finite (dom (map_filter P m))"
proof -
  have "dom (map_filter P m) = Set.filter P (dom m)"
    unfolding map_filter_def Set.filter_def dom_def
    by auto
  then show ?thesis
    using assms
    by (simp add: Set.filter_def)
qed

definition map_drop :: "'a ⇒ ('a ⇀ 'b) ⇒ ('a ⇀ 'b)" where
"map_drop a = map_filter (λa'. a' ≠ a)"

parametric_constant map_drop_transfer[transfer_rule]: map_drop_def

definition map_drop_set :: "'a set ⇒ ('a ⇀ 'b) ⇒ ('a ⇀ 'b)" where
"map_drop_set A = map_filter (λa. a ∉ A)"

parametric_constant map_drop_set_transfer[transfer_rule]: map_drop_set_def

definition map_restrict_set :: "'a set ⇒ ('a ⇀ 'b) ⇒ ('a ⇀ 'b)" where
"map_restrict_set A = map_filter (λa. a ∈ A)"

parametric_constant map_restrict_set_transfer[transfer_rule]: map_restrict_set_def

definition map_pred :: "('a ⇒ 'b ⇒ bool) ⇒ ('a ⇀ 'b) ⇒ bool" where
"map_pred P m ⟷ (∀x. case m x of None ⇒ True | Some y ⇒ P x y)"

parametric_constant map_pred_transfer[transfer_rule]: map_pred_def

definition rel_map_on_set :: "'a set ⇒ ('b ⇒ 'c ⇒ bool) ⇒ ('a ⇀ 'b) ⇒ ('a ⇀ 'c) ⇒ bool" where
"rel_map_on_set S P = eq_onp (λx. x ∈ S) ===> rel_option P"

definition set_of_map :: "('a ⇀ 'b) ⇒ ('a × 'b) set" where
"set_of_map m = {(k, v)|k v. m k = Some v}"

lemma set_of_map_alt_def: "set_of_map m = (λk. (k, the (m k))) ` dom m"
unfolding set_of_map_def dom_def
by auto

lemma set_of_map_finite: "finite (dom m) ⟹ finite (set_of_map m)"
unfolding set_of_map_alt_def
by auto

lemma set_of_map_inj: "inj set_of_map"
proof
  fix x y
  assume "set_of_map x = set_of_map y"
  hence "(x a = Some b) = (y a = Some b)" for a b
    unfolding set_of_map_def by auto
  hence "x k = y k" for k
    by (metis not_None_eq)
  thus "x = y" ..
qed

end


subsection ‹Abstract characterisation›

typedef ('a, 'b) fmap = "{m. finite (dom m)} :: ('a ⇀ 'b) set"
  morphisms fmlookup Abs_fmap
proof
  show "Map.empty ∈ {m. finite (dom m)}"
    by auto
qed

setup_lifting type_definition_fmap

lemma fmlookup_finite[intro, simp]: "finite (dom (fmlookup m))"
using fmap.fmlookup by auto

lemma fmap_ext:
  assumes "⋀x. fmlookup m x = fmlookup n x"
  shows "m = n"
using assms
by transfer' auto


subsection ‹Operations›

context
  includes fset.lifting
begin

lift_definition fmran :: "('a, 'b) fmap ⇒ 'b fset"
  is ran
  parametric ran_transfer
by (rule finite_ran)

lemma fmlookup_ran_iff: "y |∈| fmran m ⟷ (∃x. fmlookup m x = Some y)"
by transfer' (auto simp: ran_def)

lemma fmranI: "fmlookup m x = Some y ⟹ y |∈| fmran m" by (auto simp: fmlookup_ran_iff)

lemma fmranE[elim]:
  assumes "y |∈| fmran m"
  obtains x where "fmlookup m x = Some y"
using assms by (auto simp: fmlookup_ran_iff)

lift_definition fmdom :: "('a, 'b) fmap ⇒ 'a fset"
  is dom
  parametric dom_transfer
.

lemma fmlookup_dom_iff: "x |∈| fmdom m ⟷ (∃a. fmlookup m x = Some a)"
by transfer' auto

lemma fmdom_notI: "fmlookup m x = None ⟹ x |∉| fmdom m" by (simp add: fmlookup_dom_iff)
lemma fmdomI: "fmlookup m x = Some y ⟹ x |∈| fmdom m" by (simp add: fmlookup_dom_iff)
lemma fmdom_notD[dest]: "x |∉| fmdom m ⟹ fmlookup m x = None" by (simp add: fmlookup_dom_iff)

lemma fmdomE[elim]:
  assumes "x |∈| fmdom m"
  obtains y where "fmlookup m x = Some y"
using assms by (auto simp: fmlookup_dom_iff)

lift_definition fmdom' :: "('a, 'b) fmap ⇒ 'a set"
  is dom
  parametric dom_transfer
.

lemma fmlookup_dom'_iff: "x ∈ fmdom' m ⟷ (∃a. fmlookup m x = Some a)"
by transfer' auto

lemma fmdom'_notI: "fmlookup m x = None ⟹ x ∉ fmdom' m" by (simp add: fmlookup_dom'_iff)
lemma fmdom'I: "fmlookup m x = Some y ⟹ x ∈ fmdom' m" by (simp add: fmlookup_dom'_iff)
lemma fmdom'_notD[dest]: "x ∉ fmdom' m ⟹ fmlookup m x = None" by (simp add: fmlookup_dom'_iff)

lemma fmdom'E[elim]:
  assumes "x ∈ fmdom' m"
  obtains x y where "fmlookup m x = Some y"
using assms by (auto simp: fmlookup_dom'_iff)

lemma fmdom'_alt_def: "fmdom' m = fset (fmdom m)"
by transfer' force

lift_definition fmempty :: "('a, 'b) fmap"
  is Map.empty
by simp

lemma fmempty_lookup[simp]: "fmlookup fmempty x = None"
by transfer' simp

lemma fmdom_empty[simp]: "fmdom fmempty = {||}" by transfer' simp
lemma fmdom'_empty[simp]: "fmdom' fmempty = {}" by transfer' simp
lemma fmran_empty[simp]: "fmran fmempty = fempty" by transfer' (auto simp: ran_def map_filter_def)

lift_definition fmupd :: "'a ⇒ 'b ⇒ ('a, 'b) fmap ⇒ ('a, 'b) fmap"
  is map_upd
  parametric map_upd_transfer
unfolding map_upd_def[abs_def]
by simp

lemma fmupd_lookup[simp]: "fmlookup (fmupd a b m) a' = (if a = a' then Some b else fmlookup m a')"
by transfer' (auto simp: map_upd_def)

lemma fmdom_fmupd[simp]: "fmdom (fmupd a b m) = finsert a (fmdom m)" by transfer (simp add: map_upd_def)
lemma fmdom'_fmupd[simp]: "fmdom' (fmupd a b m) = insert a (fmdom' m)" by transfer (simp add: map_upd_def)

lift_definition fmfilter :: "('a ⇒ bool) ⇒ ('a, 'b) fmap ⇒ ('a, 'b) fmap"
  is map_filter
  parametric map_filter_transfer
by auto

lemma fmdom_filter[simp]: "fmdom (fmfilter P m) = ffilter P (fmdom m)"
by transfer' (auto simp: map_filter_def Set.filter_def split: if_splits)

lemma fmdom'_filter[simp]: "fmdom' (fmfilter P m) = Set.filter P (fmdom' m)"
by transfer' (auto simp: map_filter_def Set.filter_def split: if_splits)

lemma fmlookup_filter[simp]: "fmlookup (fmfilter P m) x = (if P x then fmlookup m x else None)"
by transfer' (auto simp: map_filter_def)

lemma fmfilter_empty[simp]: "fmfilter P fmempty = fmempty"
by transfer' (auto simp: map_filter_def)

lemma fmfilter_true[simp]:
  assumes "⋀x y. fmlookup m x = Some y ⟹ P x"
  shows "fmfilter P m = m"
proof (rule fmap_ext)
  fix x
  have "fmlookup m x = None" if "¬ P x"
    using that assms by fastforce
  then show "fmlookup (fmfilter P m) x = fmlookup m x"
    by simp
qed

lemma fmfilter_false[simp]:
  assumes "⋀x y. fmlookup m x = Some y ⟹ ¬ P x"
  shows "fmfilter P m = fmempty"
using assms by transfer' (fastforce simp: map_filter_def)

lemma fmfilter_comp[simp]: "fmfilter P (fmfilter Q m) = fmfilter (λx. P x ∧ Q x) m"
by transfer' (auto simp: map_filter_def)

lemma fmfilter_comm: "fmfilter P (fmfilter Q m) = fmfilter Q (fmfilter P m)"
unfolding fmfilter_comp by meson

lemma fmfilter_cong[cong]:
  assumes "⋀x y. fmlookup m x = Some y ⟹ P x = Q x"
  shows "fmfilter P m = fmfilter Q m"
proof (rule fmap_ext)
  fix x
  have "fmlookup m x = None" if "P x ≠ Q x"
    using that assms by fastforce
  then show "fmlookup (fmfilter P m) x = fmlookup (fmfilter Q m) x"
    by auto
qed

lemma fmfilter_cong'[fundef_cong]:
  assumes "m = n" "⋀x. x ∈ fmdom' m ⟹ P x = Q x"
  shows "fmfilter P m = fmfilter Q n"
using assms(2) unfolding assms(1)
by (rule fmfilter_cong) (metis fmdom'I)

lemma fmfilter_upd[simp]:
  "fmfilter P (fmupd x y m) = (if P x then fmupd x y (fmfilter P m) else fmfilter P m)"
by transfer' (auto simp: map_upd_def map_filter_def)

lift_definition fmdrop :: "'a ⇒ ('a, 'b) fmap ⇒ ('a, 'b) fmap"
  is map_drop
  parametric map_drop_transfer
unfolding map_drop_def by auto

lemma fmdrop_lookup[simp]: "fmlookup (fmdrop a m) a = None"
by transfer' (auto simp: map_drop_def map_filter_def)

lift_definition fmdrop_set :: "'a set ⇒ ('a, 'b) fmap ⇒ ('a, 'b) fmap"
  is map_drop_set
  parametric map_drop_set_transfer
unfolding map_drop_set_def by auto

lift_definition fmdrop_fset :: "'a fset ⇒ ('a, 'b) fmap ⇒ ('a, 'b) fmap"
  is map_drop_set
  parametric map_drop_set_transfer
unfolding map_drop_set_def by auto

lift_definition fmrestrict_set :: "'a set ⇒ ('a, 'b) fmap ⇒ ('a, 'b) fmap"
  is map_restrict_set
  parametric map_restrict_set_transfer
unfolding map_restrict_set_def by auto

lift_definition fmrestrict_fset :: "'a fset ⇒ ('a, 'b) fmap ⇒ ('a, 'b) fmap"
  is map_restrict_set
  parametric map_restrict_set_transfer
unfolding map_restrict_set_def by auto

lemma fmfilter_alt_defs:
  "fmdrop a = fmfilter (λa'. a' ≠ a)"
  "fmdrop_set A = fmfilter (λa. a ∉ A)"
  "fmdrop_fset B = fmfilter (λa. a |∉| B)"
  "fmrestrict_set A = fmfilter (λa. a ∈ A)"
  "fmrestrict_fset B = fmfilter (λa. a |∈| B)"
by (transfer'; simp add: map_drop_def map_drop_set_def map_restrict_set_def)+

lemma fmdom_drop[simp]: "fmdom (fmdrop a m) = fmdom m - {|a|}" unfolding fmfilter_alt_defs by auto
lemma fmdom'_drop[simp]: "fmdom' (fmdrop a m) = fmdom' m - {a}" unfolding fmfilter_alt_defs by auto
lemma fmdom'_drop_set[simp]: "fmdom' (fmdrop_set A m) = fmdom' m - A" unfolding fmfilter_alt_defs by auto
lemma fmdom_drop_fset[simp]: "fmdom (fmdrop_fset A m) = fmdom m - A" unfolding fmfilter_alt_defs by auto
lemma fmdom'_restrict_set: "fmdom' (fmrestrict_set A m) ⊆ A" unfolding fmfilter_alt_defs by auto
lemma fmdom_restrict_fset: "fmdom (fmrestrict_fset A m) |⊆| A" unfolding fmfilter_alt_defs by auto

lemma fmdom'_drop_fset[simp]: "fmdom' (fmdrop_fset A m) = fmdom' m - fset A"
unfolding fmfilter_alt_defs by transfer' (auto simp: map_filter_def split: if_splits)

lemma fmdom'_restrict_fset: "fmdom' (fmrestrict_fset A m) ⊆ fset A"
unfolding fmfilter_alt_defs by transfer' (auto simp: map_filter_def)

lemma fmlookup_drop[simp]:
  "fmlookup (fmdrop a m) x = (if x ≠ a then fmlookup m x else None)"
unfolding fmfilter_alt_defs by simp

lemma fmlookup_drop_set[simp]:
  "fmlookup (fmdrop_set A m) x = (if x ∉ A then fmlookup m x else None)"
unfolding fmfilter_alt_defs by simp

lemma fmlookup_drop_fset[simp]:
  "fmlookup (fmdrop_fset A m) x = (if x |∉| A then fmlookup m x else None)"
unfolding fmfilter_alt_defs by simp

lemma fmlookup_restrict_set[simp]:
  "fmlookup (fmrestrict_set A m) x = (if x ∈ A then fmlookup m x else None)"
unfolding fmfilter_alt_defs by simp

lemma fmlookup_restrict_fset[simp]:
  "fmlookup (fmrestrict_fset A m) x = (if x |∈| A then fmlookup m x else None)"
unfolding fmfilter_alt_defs by simp

lemma fmrestrict_set_dom[simp]: "fmrestrict_set (fmdom' m) m = m"
  by (rule fmap_ext) auto

lemma fmrestrict_fset_dom[simp]: "fmrestrict_fset (fmdom m) m = m"
  by (rule fmap_ext) auto

lemma fmdrop_empty[simp]: "fmdrop a fmempty = fmempty"
  unfolding fmfilter_alt_defs by simp

lemma fmdrop_set_empty[simp]: "fmdrop_set A fmempty = fmempty"
  unfolding fmfilter_alt_defs by simp

lemma fmdrop_fset_empty[simp]: "fmdrop_fset A fmempty = fmempty"
  unfolding fmfilter_alt_defs by simp

lemma fmrestrict_set_empty[simp]: "fmrestrict_set A fmempty = fmempty"
  unfolding fmfilter_alt_defs by simp

lemma fmrestrict_fset_empty[simp]: "fmrestrict_fset A fmempty = fmempty"
  unfolding fmfilter_alt_defs by simp

lemma fmdrop_set_null[simp]: "fmdrop_set {} m = m"
  by (rule fmap_ext) auto

lemma fmdrop_fset_null[simp]: "fmdrop_fset {||} m = m"
  by (rule fmap_ext) auto

lemma fmdrop_set_single[simp]: "fmdrop_set {a} m = fmdrop a m"
  unfolding fmfilter_alt_defs by simp

lemma fmdrop_fset_single[simp]: "fmdrop_fset {|a|} m = fmdrop a m"
  unfolding fmfilter_alt_defs by simp

lemma fmrestrict_set_null[simp]: "fmrestrict_set {} m = fmempty"
  unfolding fmfilter_alt_defs by simp

lemma fmrestrict_fset_null[simp]: "fmrestrict_fset {||} m = fmempty"
  unfolding fmfilter_alt_defs by simp

lemma fmdrop_comm: "fmdrop a (fmdrop b m) = fmdrop b (fmdrop a m)"
unfolding fmfilter_alt_defs by (rule fmfilter_comm)

lemma fmdrop_set_insert[simp]: "fmdrop_set (insert x S) m = fmdrop x (fmdrop_set S m)"
by (rule fmap_ext) auto

lemma fmdrop_fset_insert[simp]: "fmdrop_fset (finsert x S) m = fmdrop x (fmdrop_fset S m)"
by (rule fmap_ext) auto

lift_definition fmadd :: "('a, 'b) fmap ⇒ ('a, 'b) fmap ⇒ ('a, 'b) fmap" (infixl "++⇩f" 100)
  is map_add
  parametric map_add_transfer
by simp

lemma fmlookup_add[simp]:
  "fmlookup (m ++⇩f n) x = (if x |∈| fmdom n then fmlookup n x else fmlookup m x)"
  by transfer' (auto simp: map_add_def split: option.splits)

lemma fmdom_add[simp]: "fmdom (m ++⇩f n) = fmdom m |∪| fmdom n" by transfer' auto
lemma fmdom'_add[simp]: "fmdom' (m ++⇩f n) = fmdom' m ∪ fmdom' n" by transfer' auto

lemma fmadd_drop_left_dom: "fmdrop_fset (fmdom n) m ++⇩f n = m ++⇩f n"
  by (rule fmap_ext) auto

lemma fmadd_restrict_right_dom: "fmrestrict_fset (fmdom n) (m ++⇩f n) = n"
  by (rule fmap_ext) auto

lemma fmfilter_add_distrib[simp]: "fmfilter P (m ++⇩f n) = fmfilter P m ++⇩f fmfilter P n"
by transfer' (auto simp: map_filter_def map_add_def)

lemma fmdrop_add_distrib[simp]: "fmdrop a (m ++⇩f n) = fmdrop a m ++⇩f fmdrop a n"
  unfolding fmfilter_alt_defs by simp

lemma fmdrop_set_add_distrib[simp]: "fmdrop_set A (m ++⇩f n) = fmdrop_set A m ++⇩f fmdrop_set A n"
  unfolding fmfilter_alt_defs by simp

lemma fmdrop_fset_add_distrib[simp]: "fmdrop_fset A (m ++⇩f n) = fmdrop_fset A m ++⇩f fmdrop_fset A n"
  unfolding fmfilter_alt_defs by simp

lemma fmrestrict_set_add_distrib[simp]:
  "fmrestrict_set A (m ++⇩f n) = fmrestrict_set A m ++⇩f fmrestrict_set A n"
  unfolding fmfilter_alt_defs by simp

lemma fmrestrict_fset_add_distrib[simp]:
  "fmrestrict_fset A (m ++⇩f n) = fmrestrict_fset A m ++⇩f fmrestrict_fset A n"
  unfolding fmfilter_alt_defs by simp

lemma fmadd_empty[simp]: "fmempty ++⇩f m = m" "m ++⇩f fmempty = m"
by (transfer'; auto)+

lemma fmadd_idempotent[simp]: "m ++⇩f m = m"
by transfer' (auto simp: map_add_def split: option.splits)

lemma fmadd_assoc[simp]: "m ++⇩f (n ++⇩f p) = m ++⇩f n ++⇩f p"
by transfer' simp

lemma fmadd_fmupd[simp]: "m ++⇩f fmupd a b n = fmupd a b (m ++⇩f n)"
by (rule fmap_ext) simp

lift_definition fmpred :: "('a ⇒ 'b ⇒ bool) ⇒ ('a, 'b) fmap ⇒ bool"
  is map_pred
  parametric map_pred_transfer
.

lemma fmpredI[intro]:
  assumes "⋀x y. fmlookup m x = Some y ⟹ P x y"
  shows "fmpred P m"
using assms
by transfer' (auto simp: map_pred_def split: option.splits)

lemma fmpredD[dest]: "fmpred P m ⟹ fmlookup m x = Some y ⟹ P x y"
by transfer' (auto simp: map_pred_def split: option.split_asm)

lemma fmpred_iff: "fmpred P m ⟷ (∀x y. fmlookup m x = Some y ⟶ P x y)"
by auto

lemma fmpred_alt_def: "fmpred P m ⟷ fBall (fmdom m) (λx. P x (the (fmlookup m x)))"
unfolding fmpred_iff
apply auto
apply (rename_tac x y)
apply (erule_tac x = x in fBallE)
apply simp
by (simp add: fmlookup_dom_iff)

lemma fmpred_empty[intro!, simp]: "fmpred P fmempty"
by auto

lemma fmpred_upd[intro]: "fmpred P m ⟹ P x y ⟹ fmpred P (fmupd x y m)"
by transfer' (auto simp: map_pred_def map_upd_def)

lemma fmpred_updD[dest]: "fmpred P (fmupd x y m) ⟹ P x y"
by auto

lemma fmpred_add[intro]: "fmpred P m ⟹ fmpred P n ⟹ fmpred P (m ++⇩f n)"
by transfer' (auto simp: map_pred_def map_add_def split: option.splits)

lemma fmpred_filter[intro]: "fmpred P m ⟹ fmpred P (fmfilter Q m)"
by transfer' (auto simp: map_pred_def map_filter_def)

lemma fmpred_drop[intro]: "fmpred P m ⟹ fmpred P (fmdrop a m)"
  by (auto simp: fmfilter_alt_defs)

lemma fmpred_drop_set[intro]: "fmpred P m ⟹ fmpred P (fmdrop_set A m)"
  by (auto simp: fmfilter_alt_defs)

lemma fmpred_drop_fset[intro]: "fmpred P m ⟹ fmpred P (fmdrop_fset A m)"
  by (auto simp: fmfilter_alt_defs)

lemma fmpred_restrict_set[intro]: "fmpred P m ⟹ fmpred P (fmrestrict_set A m)"
  by (auto simp: fmfilter_alt_defs)

lemma fmpred_restrict_fset[intro]: "fmpred P m ⟹ fmpred P (fmrestrict_fset A m)"
  by (auto simp: fmfilter_alt_defs)

lemma fmpred_cases[consumes 1]:
  assumes "fmpred P m"
  obtains (none) "fmlookup m x = None" | (some) y where "fmlookup m x = Some y" "P x y"
using assms by auto

lift_definition fmsubset :: "('a, 'b) fmap ⇒ ('a, 'b) fmap ⇒ bool" (infix "⊆⇩f" 50)
  is map_le
.

lemma fmsubset_alt_def: "m ⊆⇩f n ⟷ fmpred (λk v. fmlookup n k = Some v) m"
by transfer' (auto simp: map_pred_def map_le_def dom_def split: option.splits)

lemma fmsubset_pred: "fmpred P m ⟹ n ⊆⇩f m ⟹ fmpred P n"
unfolding fmsubset_alt_def fmpred_iff
by auto

lemma fmsubset_filter_mono: "m ⊆⇩f n ⟹ fmfilter P m ⊆⇩f fmfilter P n"
unfolding fmsubset_alt_def fmpred_iff
by auto

lemma fmsubset_drop_mono: "m ⊆⇩f n ⟹ fmdrop a m ⊆⇩f fmdrop a n"
unfolding fmfilter_alt_defs by (rule fmsubset_filter_mono)

lemma fmsubset_drop_set_mono: "m ⊆⇩f n ⟹ fmdrop_set A m ⊆⇩f fmdrop_set A n"
unfolding fmfilter_alt_defs by (rule fmsubset_filter_mono)

lemma fmsubset_drop_fset_mono: "m ⊆⇩f n ⟹ fmdrop_fset A m ⊆⇩f fmdrop_fset A n"
unfolding fmfilter_alt_defs by (rule fmsubset_filter_mono)

lemma fmsubset_restrict_set_mono: "m ⊆⇩f n ⟹ fmrestrict_set A m ⊆⇩f fmrestrict_set A n"
unfolding fmfilter_alt_defs by (rule fmsubset_filter_mono)

lemma fmsubset_restrict_fset_mono: "m ⊆⇩f n ⟹ fmrestrict_fset A m ⊆⇩f fmrestrict_fset A n"
unfolding fmfilter_alt_defs by (rule fmsubset_filter_mono)

lift_definition fset_of_fmap :: "('a, 'b) fmap ⇒ ('a × 'b) fset" is set_of_map
by (rule set_of_map_finite)

lemma fset_of_fmap_inj[intro, simp]: "inj fset_of_fmap"
apply rule
apply transfer'
using set_of_map_inj unfolding inj_def by auto

lemma fset_of_fmap_iff[simp]: "(a, b) |∈| fset_of_fmap m ⟷ fmlookup m a = Some b"
by transfer' (auto simp: set_of_map_def)

lemma fset_of_fmap_iff'[simp]: "(a, b) ∈ fset (fset_of_fmap m) ⟷ fmlookup m a = Some b"
by transfer' (auto simp: set_of_map_def)


lift_definition fmap_of_list :: "('a × 'b) list ⇒ ('a, 'b) fmap"
  is map_of
  parametric map_of_transfer
by (rule finite_dom_map_of)

lemma fmap_of_list_simps[simp]:
  "fmap_of_list [] = fmempty"
  "fmap_of_list ((k, v) # kvs) = fmupd k v (fmap_of_list kvs)"
by (transfer, simp add: map_upd_def)+

lemma fmap_of_list_app[simp]: "fmap_of_list (xs @ ys) = fmap_of_list ys ++⇩f fmap_of_list xs"
by transfer' simp

lemma fmupd_alt_def: "fmupd k v m = m ++⇩f fmap_of_list [(k, v)]"
by transfer' (auto simp: map_upd_def)

lemma fmpred_of_list[intro]:
  assumes "⋀k v. (k, v) ∈ set xs ⟹ P k v"
  shows "fmpred P (fmap_of_list xs)"
using assms
by (induction xs) (transfer'; auto simp: map_pred_def)+

lemma fmap_of_list_SomeD: "fmlookup (fmap_of_list xs) k = Some v ⟹ (k, v) ∈ set xs"
by transfer' (auto dest: map_of_SomeD)

lemma fmdom_fmap_of_list[simp]: "fmdom (fmap_of_list xs) = fset_of_list (map fst xs)"
apply transfer'
apply (subst dom_map_of_conv_image_fst)
apply auto
done

lift_definition fmrel_on_fset :: "'a fset ⇒ ('b ⇒ 'c ⇒ bool) ⇒ ('a, 'b) fmap ⇒ ('a, 'c) fmap ⇒ bool"
  is rel_map_on_set
.

lemma fmrel_on_fset_alt_def: "fmrel_on_fset S P m n ⟷ fBall S (λx. rel_option P (fmlookup m x) (fmlookup n x))"
by transfer' (auto simp: rel_map_on_set_def eq_onp_def rel_fun_def)

lemma fmrel_on_fsetI[intro]:
  assumes "⋀x. x |∈| S ⟹ rel_option P (fmlookup m x) (fmlookup n x)"
  shows "fmrel_on_fset S P m n"
using assms
unfolding fmrel_on_fset_alt_def by auto

lemma fmrel_on_fset_mono[mono]: "R ≤ Q ⟹ fmrel_on_fset S R ≤ fmrel_on_fset S Q"
unfolding fmrel_on_fset_alt_def[abs_def]
apply (intro le_funI fBall_mono)
using option.rel_mono by auto

lemma fmrel_on_fsetD: "x |∈| S ⟹ fmrel_on_fset S P m n ⟹ rel_option P (fmlookup m x) (fmlookup n x)"
unfolding fmrel_on_fset_alt_def
by auto

lemma fmrel_on_fsubset: "fmrel_on_fset S R m n ⟹ T |⊆| S ⟹ fmrel_on_fset T R m n"
unfolding fmrel_on_fset_alt_def
by auto

lemma fmrel_on_fset_unionI:
  "fmrel_on_fset A R m n ⟹ fmrel_on_fset B R m n ⟹ fmrel_on_fset (A |∪| B) R m n"
unfolding fmrel_on_fset_alt_def
by auto

lemma fmrel_on_fset_updateI:
  assumes "fmrel_on_fset S P m n" "P v⇩1 v⇩2"
  shows "fmrel_on_fset (finsert k S) P (fmupd k v⇩1 m) (fmupd k v⇩2 n)"
using assms
unfolding fmrel_on_fset_alt_def
by auto

end


subsection ‹BNF setup›

lift_bnf ('a, fmran': 'b) fmap [wits: Map.empty]
  for map: fmmap
      rel: fmrel
  by auto

declare fmap.pred_mono[mono]

context includes lifting_syntax begin

lemma fmmap_transfer[transfer_rule]:
  "((=) ===> pcr_fmap (=) (=) ===> pcr_fmap (=) (=)) (λf. (∘) (map_option f)) fmmap"
  unfolding fmmap_def
  by (rule rel_funI ext)+ (auto simp: fmap.Abs_fmap_inverse fmap.pcr_cr_eq cr_fmap_def)

lemma fmran'_transfer[transfer_rule]:
  "(pcr_fmap (=) (=) ===> (=)) (λx. UNION (range x) set_option) fmran'"
  unfolding fmran'_def fmap.pcr_cr_eq cr_fmap_def by fastforce

lemma fmrel_transfer[transfer_rule]:
  "((=) ===> pcr_fmap (=) (=) ===> pcr_fmap (=) (=) ===> (=)) rel_map fmrel"
  unfolding fmrel_def fmap.pcr_cr_eq cr_fmap_def vimage2p_def by fastforce

end


lemma fmran'_alt_def: "fmran' m = fset (fmran m)"
including fset.lifting
by transfer' (auto simp: ran_def fun_eq_iff)

lemma fmlookup_ran'_iff: "y ∈ fmran' m ⟷ (∃x. fmlookup m x = Some y)"
by transfer' (auto simp: ran_def)

lemma fmran'I: "fmlookup m x = Some y ⟹ y ∈ fmran' m" by (auto simp: fmlookup_ran'_iff)

lemma fmran'E[elim]:
  assumes "y ∈ fmran' m"
  obtains x where "fmlookup m x = Some y"
using assms by (auto simp: fmlookup_ran'_iff)

lemma fmrel_iff: "fmrel R m n ⟷ (∀x. rel_option R (fmlookup m x) (fmlookup n x))"
by transfer' (auto simp: rel_fun_def)

lemma fmrelI[intro]:
  assumes "⋀x. rel_option R (fmlookup m x) (fmlookup n x)"
  shows "fmrel R m n"
using assms
by transfer' auto

lemma fmrel_upd[intro]: "fmrel P m n ⟹ P x y ⟹ fmrel P (fmupd k x m) (fmupd k y n)"
by transfer' (auto simp: map_upd_def rel_fun_def)

lemma fmrelD[dest]: "fmrel P m n ⟹ rel_option P (fmlookup m x) (fmlookup n x)"
by transfer' (auto simp: rel_fun_def)

lemma fmrel_addI[intro]:
  assumes "fmrel P m n" "fmrel P a b"
  shows "fmrel P (m ++⇩f a) (n ++⇩f b)"
using assms
apply transfer'
apply (auto simp: rel_fun_def map_add_def)
by (metis option.case_eq_if option.collapse option.rel_sel)

lemma fmrel_cases[consumes 1]:
  assumes "fmrel P m n"
  obtains (none) "fmlookup m x = None" "fmlookup n x = None"
        | (some) a b where "fmlookup m x = Some a" "fmlookup n x = Some b" "P a b"
proof -
  from assms have "rel_option P (fmlookup m x) (fmlookup n x)"
    by auto
  then show thesis
    using none some
    by (cases rule: option.rel_cases) auto
qed

lemma fmrel_filter[intro]: "fmrel P m n ⟹ fmrel P (fmfilter Q m) (fmfilter Q n)"
unfolding fmrel_iff by auto

lemma fmrel_drop[intro]: "fmrel P m n ⟹ fmrel P (fmdrop a m) (fmdrop a n)"
  unfolding fmfilter_alt_defs by blast

lemma fmrel_drop_set[intro]: "fmrel P m n ⟹ fmrel P (fmdrop_set A m) (fmdrop_set A n)"
  unfolding fmfilter_alt_defs by blast

lemma fmrel_drop_fset[intro]: "fmrel P m n ⟹ fmrel P (fmdrop_fset A m) (fmdrop_fset A n)"
  unfolding fmfilter_alt_defs by blast

lemma fmrel_restrict_set[intro]: "fmrel P m n ⟹ fmrel P (fmrestrict_set A m) (fmrestrict_set A n)"
  unfolding fmfilter_alt_defs by blast

lemma fmrel_restrict_fset[intro]: "fmrel P m n ⟹ fmrel P (fmrestrict_fset A m) (fmrestrict_fset A n)"
  unfolding fmfilter_alt_defs by blast

lemma fmrel_on_fset_fmrel_restrict:
  "fmrel_on_fset S P m n ⟷ fmrel P (fmrestrict_fset S m) (fmrestrict_fset S n)"
unfolding fmrel_on_fset_alt_def fmrel_iff
by auto

lemma fmrel_on_fset_refl_strong:
  assumes "⋀x y. x |∈| S ⟹ fmlookup m x = Some y ⟹ P y y"
  shows "fmrel_on_fset S P m m"
unfolding fmrel_on_fset_fmrel_restrict fmrel_iff
using assms
by (simp add: option.rel_sel)

lemma fmrel_on_fset_addI:
  assumes "fmrel_on_fset S P m n" "fmrel_on_fset S P a b"
  shows "fmrel_on_fset S P (m ++⇩f a) (n ++⇩f b)"
using assms
unfolding fmrel_on_fset_fmrel_restrict
by auto

lemma fmrel_fmdom_eq:
  assumes "fmrel P x y"
  shows "fmdom x = fmdom y"
proof -
  have "a |∈| fmdom x ⟷ a |∈| fmdom y" for a
    proof -
      have "rel_option P (fmlookup x a) (fmlookup y a)"
        using assms by (simp add: fmrel_iff)
      thus ?thesis
        by cases (auto intro: fmdomI)
    qed
  thus ?thesis
    by auto
qed

lemma fmrel_fmdom'_eq: "fmrel P x y ⟹ fmdom' x = fmdom' y"
unfolding fmdom'_alt_def
by (metis fmrel_fmdom_eq)

lemma fmrel_rel_fmran:
  assumes "fmrel P x y"
  shows "rel_fset P (fmran x) (fmran y)"
proof -
  {
    fix b
    assume "b |∈| fmran x"
    then obtain a where "fmlookup x a = Some b"
      by auto
    moreover have "rel_option P (fmlookup x a) (fmlookup y a)"
      using assms by auto
    ultimately have "∃b'. b' |∈| fmran y ∧ P b b'"
      by (metis option_rel_Some1 fmranI)
  }
  moreover
  {
    fix b
    assume "b |∈| fmran y"
    then obtain a where "fmlookup y a = Some b"
      by auto
    moreover have "rel_option P (fmlookup x a) (fmlookup y a)"
      using assms by auto
    ultimately have "∃b'. b' |∈| fmran x ∧ P b' b"
      by (metis option_rel_Some2 fmranI)
  }
  ultimately show ?thesis
    unfolding rel_fset_alt_def
    by auto
qed

lemma fmrel_rel_fmran': "fmrel P x y ⟹ rel_set P (fmran' x) (fmran' y)"
unfolding fmran'_alt_def
by (metis fmrel_rel_fmran rel_fset_fset)

lemma pred_fmap_fmpred[simp]: "pred_fmap P = fmpred (λ_. P)"
unfolding fmap.pred_set fmran'_alt_def
including fset.lifting
apply transfer'
apply (rule ext)
apply (auto simp: map_pred_def ran_def split: option.splits dest: )
done

lemma pred_fmap_id[simp]: "pred_fmap id (fmmap f m) ⟷ pred_fmap f m"
unfolding fmap.pred_set fmap.set_map
by simp

lemma pred_fmapD: "pred_fmap P m ⟹ x |∈| fmran m ⟹ P x"
by auto

lemma fmlookup_map[simp]: "fmlookup (fmmap f m) x = map_option f (fmlookup m x)"
by transfer' auto

lemma fmpred_map[simp]: "fmpred P (fmmap f m) ⟷ fmpred (λk v. P k (f v)) m"
unfolding fmpred_iff pred_fmap_def fmap.set_map
by auto

lemma fmpred_id[simp]: "fmpred (λ_. id) (fmmap f m) ⟷ fmpred (λ_. f) m"
by simp

lemma fmmap_add[simp]: "fmmap f (m ++⇩f n) = fmmap f m ++⇩f fmmap f n"
by transfer' (auto simp: map_add_def fun_eq_iff split: option.splits)

lemma fmmap_empty[simp]: "fmmap f fmempty = fmempty"
by transfer auto

lemma fmdom_map[simp]: "fmdom (fmmap f m) = fmdom m"
including fset.lifting
by transfer' simp

lemma fmdom'_map[simp]: "fmdom' (fmmap f m) = fmdom' m"
by transfer' simp

lemma fmran_fmmap[simp]: "fmran (fmmap f m) = f |`| fmran m"
including fset.lifting
by transfer' (auto simp: ran_def)

lemma fmran'_fmmap[simp]: "fmran' (fmmap f m) = f ` fmran' m"
by transfer' (auto simp: ran_def)

lemma fmfilter_fmmap[simp]: "fmfilter P (fmmap f m) = fmmap f (fmfilter P m)"
by transfer' (auto simp: map_filter_def)

lemma fmdrop_fmmap[simp]: "fmdrop a (fmmap f m) = fmmap f (fmdrop a m)" unfolding fmfilter_alt_defs by simp
lemma fmdrop_set_fmmap[simp]: "fmdrop_set A (fmmap f m) = fmmap f (fmdrop_set A m)" unfolding fmfilter_alt_defs by simp
lemma fmdrop_fset_fmmap[simp]: "fmdrop_fset A (fmmap f m) = fmmap f (fmdrop_fset A m)" unfolding fmfilter_alt_defs by simp
lemma fmrestrict_set_fmmap[simp]: "fmrestrict_set A (fmmap f m) = fmmap f (fmrestrict_set A m)" unfolding fmfilter_alt_defs by simp
lemma fmrestrict_fset_fmmap[simp]: "fmrestrict_fset A (fmmap f m) = fmmap f (fmrestrict_fset A m)" unfolding fmfilter_alt_defs by simp

lemma fmmap_subset[intro]: "m ⊆⇩f n ⟹ fmmap f m ⊆⇩f fmmap f n"
by transfer' (auto simp: map_le_def)

lemma fmmap_fset_of_fmap: "fset_of_fmap (fmmap f m) = (λ(k, v). (k, f v)) |`| fset_of_fmap m"
including fset.lifting
by transfer' (auto simp: set_of_map_def)


subsection ‹@{const size} setup›

definition size_fmap :: "('a ⇒ nat) ⇒ ('b ⇒ nat) ⇒ ('a, 'b) fmap ⇒ nat" where
[simp]: "size_fmap f g m = size_fset (λ(a, b). f a + g b) (fset_of_fmap m)"

instantiation fmap :: (type, type) size begin

definition size_fmap where
size_fmap_overloaded_def: "size_fmap = Finite_Map.size_fmap (λ_. 0) (λ_. 0)"

instance ..

end

lemma size_fmap_overloaded_simps[simp]: "size x = size (fset_of_fmap x)"
unfolding size_fmap_overloaded_def
by simp

lemma fmap_size_o_map: "inj h ⟹ size_fmap f g ∘ fmmap h = size_fmap f (g ∘ h)"
  unfolding size_fmap_def
  apply (auto simp: fun_eq_iff fmmap_fset_of_fmap)
  apply (subst sum.reindex)
  subgoal for m
    using prod.inj_map[unfolded map_prod_def, of "λx. x" h]
    unfolding inj_on_def
    by auto
  subgoal
    by (rule sum.cong) (auto split: prod.splits)
  done

setup ‹
BNF_LFP_Size.register_size_global @{type_name fmap} @{const_name size_fmap}
  @{thm size_fmap_overloaded_def} @{thms size_fmap_def size_fmap_overloaded_simps}
  @{thms fmap_size_o_map}
›


subsection ‹Additional operations›

lift_definition fmmap_keys :: "('a ⇒ 'b ⇒ 'c) ⇒ ('a, 'b) fmap ⇒ ('a, 'c) fmap" is
  "λf m a. map_option (f a) (m a)"
unfolding dom_def
by simp

lemma fmpred_fmmap_keys[simp]: "fmpred P (fmmap_keys f m) = fmpred (λa b. P a (f a b)) m"
by transfer' (auto simp: map_pred_def split: option.splits)

lemma fmdom_fmmap_keys[simp]: "fmdom (fmmap_keys f m) = fmdom m"
including fset.lifting
by transfer' auto

lemma fmlookup_fmmap_keys[simp]: "fmlookup (fmmap_keys f m) x = map_option (f x) (fmlookup m x)"
by transfer' simp

lemma fmfilter_fmmap_keys[simp]: "fmfilter P (fmmap_keys f m) = fmmap_keys f (fmfilter P m)"
by transfer' (auto simp: map_filter_def)

lemma fmdrop_fmmap_keys[simp]: "fmdrop a (fmmap_keys f m) = fmmap_keys f (fmdrop a m)"
unfolding fmfilter_alt_defs by simp

lemma fmdrop_set_fmmap_keys[simp]: "fmdrop_set A (fmmap_keys f m) = fmmap_keys f (fmdrop_set A m)"
unfolding fmfilter_alt_defs by simp

lemma fmdrop_fset_fmmap_keys[simp]: "fmdrop_fset A (fmmap_keys f m) = fmmap_keys f (fmdrop_fset A m)"
unfolding fmfilter_alt_defs by simp

lemma fmrestrict_set_fmmap_keys[simp]: "fmrestrict_set A (fmmap_keys f m) = fmmap_keys f (fmrestrict_set A m)"
unfolding fmfilter_alt_defs by simp

lemma fmrestrict_fset_fmmap_keys[simp]: "fmrestrict_fset A (fmmap_keys f m) = fmmap_keys f (fmrestrict_fset A m)"
unfolding fmfilter_alt_defs by simp

lemma fmmap_keys_subset[intro]: "m ⊆⇩f n ⟹ fmmap_keys f m ⊆⇩f fmmap_keys f n"
by transfer' (auto simp: map_le_def dom_def)

definition sorted_list_of_fmap :: "('a::linorder, 'b) fmap ⇒ ('a × 'b) list" where
"sorted_list_of_fmap m = map (λk. (k, the (fmlookup m k))) (sorted_list_of_fset (fmdom m))"

lemma list_all_sorted_list[simp]: "list_all P (sorted_list_of_fmap m) = fmpred (curry P) m"
unfolding sorted_list_of_fmap_def curry_def list.pred_map
apply (auto simp: list_all_iff)
including fmap.lifting fset.lifting
by (transfer; auto simp: dom_def map_pred_def split: option.splits)+

lemma map_of_sorted_list[simp]: "map_of (sorted_list_of_fmap m) = fmlookup m"
unfolding sorted_list_of_fmap_def
including fmap.lifting fset.lifting
by transfer (simp add: map_of_map_keys)


subsection ‹Lifting/transfer setup›

context includes lifting_syntax begin

lemma fmempty_transfer[simp, intro, transfer_rule]: "fmrel P fmempty fmempty"
by transfer auto

lemma fmadd_transfer[transfer_rule]:
  "(fmrel P ===> fmrel P ===> fmrel P) fmadd fmadd"
  by (intro fmrel_addI rel_funI)

lemma fmupd_transfer[transfer_rule]:
  "((=) ===> P ===> fmrel P ===> fmrel P) fmupd fmupd"
  by auto

end


subsection ‹View as datatype›

lemma fmap_distinct[simp]:
  "fmempty ≠ fmupd k v m"
  "fmupd k v m ≠ fmempty"
by (transfer'; auto simp: map_upd_def fun_eq_iff)+

lifting_update fmap.lifting

lemma fmap_exhaust[case_names fmempty fmupd, cases type: fmap]:
  assumes fmempty: "m = fmempty ⟹ P"
  assumes fmupd: "⋀x y m'. m = fmupd x y m' ⟹ x |∉| fmdom m' ⟹ P"
  shows "P"
using assms including fmap.lifting fset.lifting
proof transfer
  fix m P
  assume "finite (dom m)"
  assume empty: P if "m = Map.empty"
  assume map_upd: P if "finite (dom m')" "m = map_upd x y m'" "x ∉ dom m'" for x y m'

  show P
    proof (cases "m = Map.empty")
      case True thus ?thesis using empty by simp
    next
      case False
      hence "dom m ≠ {}" by simp
      then obtain x where "x ∈ dom m" by blast

      let ?m' = "map_drop x m"

      show ?thesis
        proof (rule map_upd)
          show "finite (dom ?m')"
            using ‹finite (dom m)›
            unfolding map_drop_def
            by auto
        next
          show "m = map_upd x (the (m x)) ?m'"
            using ‹x ∈ dom m› unfolding map_drop_def map_filter_def map_upd_def
            by auto
        next
          show "x ∉ dom ?m'"
            unfolding map_drop_def map_filter_def
            by auto
        qed
    qed
qed

lemma fmap_induct[case_names fmempty fmupd, induct type: fmap]:
  assumes "P fmempty"
  assumes "(⋀x y m. P m ⟹ fmlookup m x = None ⟹ P (fmupd x y m))"
  shows "P m"
proof (induction "fmdom m" arbitrary: m rule: fset_induct_stronger)
  case empty
  hence "m = fmempty"
    by (metis fmrestrict_fset_dom fmrestrict_fset_null)
  with assms show ?case
    by simp
next
  case (insert x S)
  hence "S = fmdom (fmdrop x m)"
    by auto
  with insert have "P (fmdrop x m)"
    by auto

  have "x |∈| fmdom m"
    using insert by auto
  then obtain y where "fmlookup m x = Some y"
    by auto
  hence "m = fmupd x y (fmdrop x m)"
    by (auto intro: fmap_ext)

  show ?case
    apply (subst ‹m = _›)
    apply (rule assms)
    apply fact
    apply simp
    done
qed


subsection ‹Code setup›

instantiation fmap :: (type, equal) equal begin

definition "equal_fmap ≡ fmrel HOL.equal"

instance proof
  fix m n :: "('a, 'b) fmap"
  have "fmrel (=) m n ⟷ (m = n)"
    by transfer' (simp add: option.rel_eq rel_fun_eq)
  then show "equal_class.equal m n ⟷ (m = n)"
    unfolding equal_fmap_def
    by (simp add: equal_eq[abs_def])
qed

end

lemma fBall_alt_def: "fBall S P ⟷ (∀x. x |∈| S ⟶ P x)"
by force

lemma fmrel_code:
  "fmrel R m n ⟷
    fBall (fmdom m) (λx. rel_option R (fmlookup m x) (fmlookup n x)) ∧
    fBall (fmdom n) (λx. rel_option R (fmlookup m x) (fmlookup n x))"
unfolding fmrel_iff fmlookup_dom_iff fBall_alt_def
by (metis option.collapse option.rel_sel)

lemmas [code] =
  fmrel_code
  fmran'_alt_def
  fmdom'_alt_def
  fmfilter_alt_defs
  pred_fmap_fmpred
  fmsubset_alt_def
  fmupd_alt_def
  fmrel_on_fset_alt_def
  fmpred_alt_def


code_datatype fmap_of_list
quickcheck_generator fmap constructors: fmap_of_list

context includes fset.lifting begin

lemma fmlookup_of_list[code]: "fmlookup (fmap_of_list m) = map_of m"
by transfer simp

lemma fmempty_of_list[code]: "fmempty = fmap_of_list []"
by transfer simp

lemma fmran_of_list[code]: "fmran (fmap_of_list m) = snd |`| fset_of_list (AList.clearjunk m)"
by transfer (auto simp: ran_map_of)

lemma fmdom_of_list[code]: "fmdom (fmap_of_list m) = fst |`| fset_of_list m"
by transfer (auto simp: dom_map_of_conv_image_fst)

lemma fmfilter_of_list[code]: "fmfilter P (fmap_of_list m) = fmap_of_list (filter (λ(k, _). P k) m)"
by transfer' auto

lemma fmadd_of_list[code]: "fmap_of_list m ++⇩f fmap_of_list n = fmap_of_list (AList.merge m n)"
by transfer (simp add: merge_conv')

lemma fmmap_of_list[code]: "fmmap f (fmap_of_list m) = fmap_of_list (map (apsnd f) m)"
apply transfer
apply (subst map_of_map[symmetric])
apply (auto simp: apsnd_def map_prod_def)
done

lemma fmmap_keys_of_list[code]: "fmmap_keys f (fmap_of_list m) = fmap_of_list (map (λ(a, b). (a, f a b)) m)"
apply transfer
subgoal for f m by (induction m) (auto simp: apsnd_def map_prod_def fun_eq_iff)
done

end


subsection ‹Instances›

lemma exists_map_of:
  assumes "finite (dom m)" shows "∃xs. map_of xs = m"
  using assms
proof (induction "dom m" arbitrary: m)
  case empty
  hence "m = Map.empty"
    by auto
  moreover have "map_of [] = Map.empty"
    by simp
  ultimately show ?case
    by blast
next
  case (insert x F)
  hence "F = dom (map_drop x m)"
    unfolding map_drop_def map_filter_def dom_def by auto
  with insert have "∃xs'. map_of xs' = map_drop x m"
    by auto
  then obtain xs' where "map_of xs' = map_drop x m"
    ..
  moreover obtain y where "m x = Some y"
    using insert unfolding dom_def by blast
  ultimately have "map_of ((x, y) # xs') = m"
    using ‹insert x F = dom m›
    unfolding map_drop_def map_filter_def
    by auto
  thus ?case
    ..
qed

lemma exists_fmap_of_list: "∃xs. fmap_of_list xs = m"
by transfer (rule exists_map_of)

lemma fmap_of_list_surj[simp, intro]: "surj fmap_of_list"
proof -
  have "x ∈ range fmap_of_list" for x :: "('a, 'b) fmap"
    unfolding image_iff
    using exists_fmap_of_list by (metis UNIV_I)
  thus ?thesis by auto
qed

instance fmap :: (countable, countable) countable
proof
  obtain to_nat :: "('a × 'b) list ⇒ nat" where "inj to_nat"
    by (metis ex_inj)
  moreover have "inj (inv fmap_of_list)"
    using fmap_of_list_surj by (rule surj_imp_inj_inv)
  ultimately have "inj (to_nat ∘ inv fmap_of_list)"
    by (rule inj_comp)
  thus "∃to_nat::('a, 'b) fmap ⇒ nat. inj to_nat"
    by auto
qed

instance fmap :: (finite, finite) finite
proof
  show "finite (UNIV :: ('a, 'b) fmap set)"
    by (rule finite_imageD) auto
qed

lifting_update fmap.lifting
lifting_forget fmap.lifting

end