lib: apply consistent style to OptionMonad

Signed-off-by: Gerwin Klein <gerwin.klein@proofcraft.systems>
This commit is contained in:
Gerwin Klein 2022-12-22 13:00:48 +11:00
parent ed0cd5b282
commit 12c9c2bc21
No known key found for this signature in database
GPG Key ID: 20A847CE6AB7F5F3
1 changed files with 77 additions and 80 deletions

View File

@ -18,19 +18,29 @@ theory OptionMonad (* FIXME: this is really a Reader_Option_Monad *)
Less_Monad_Syntax
begin
section \<open>Projections\<close>
type_synonym ('s,'a) lookup = "'s \<Rightarrow> 'a option"
text \<open>Similar to map_option but the second function returns option as well\<close>
definition
opt_map :: "('s,'a) lookup \<Rightarrow> ('a \<Rightarrow> 'b option) \<Rightarrow> ('s,'b) lookup" (infixl "|>" 54)
where
definition opt_map :: "('s,'a) lookup \<Rightarrow> ('a \<Rightarrow> 'b option) \<Rightarrow> ('s,'b) lookup" (infixl "|>" 54) where
"f |> g \<equiv> \<lambda>s. case f s of None \<Rightarrow> None | Some x \<Rightarrow> g x"
abbreviation opt_map_Some :: "('s \<rightharpoonup> 'a) \<Rightarrow> ('a \<Rightarrow> 'b) \<Rightarrow> 's \<rightharpoonup> 'b" (infixl "||>" 54) where
"f ||> g \<equiv> f |> (Some \<circ> g)"
lemmas opt_map_Some_def = opt_map_def
lemma opt_map_cong [fundef_cong]:
definition map_set :: "('a \<Rightarrow> 'b set option) \<Rightarrow> 'a \<Rightarrow> 'b set" where
"map_set f \<equiv> case_option {} id \<circ> f"
definition opt_pred :: "('a \<Rightarrow> bool) \<Rightarrow> ('b \<Rightarrow> 'a option) \<Rightarrow> ('b \<Rightarrow> bool)" (infixl "|<" 55) where
"P |< proj \<equiv> (\<lambda>x. case_option False P (proj x))"
subsection \<open>Lemmas for @{const opt_map}\<close>
lemma opt_map_cong[fundef_cong]:
"\<lbrakk> f = f'; \<And>v s. f s = Some v \<Longrightarrow> g v = g' v\<rbrakk> \<Longrightarrow> f |> g = f' |> g'"
by (rule ext) (simp add: opt_map_def split: option.splits)
@ -78,8 +88,7 @@ lemma opt_map_Some_upd_Some:
"f(x \<mapsto> v) ||> g = (f ||> g)(x \<mapsto> g v)"
by (simp add: opt_map_upd_Some)
lemmas opt_map_upd[simp]
= opt_map_upd_None opt_map_upd_Some opt_map_Some_upd_Some
lemmas opt_map_upd[simp] = opt_map_upd_None opt_map_upd_Some opt_map_Some_upd_Some
lemma opt_map_upd_triv:
"t k = Some x \<Longrightarrow> (t |> f)(k := f x) = t |> f"
@ -96,17 +105,16 @@ lemma opt_map_upd_triv_None:
lemmas opt_map_upd_triv_simps = opt_map_upd_triv opt_map_Some_upd_triv opt_map_upd_triv_None
lemma opt_map_foldr_upd:
"(foldr (\<lambda>p kh. kh(p := new)) ptrs f)|> g
"foldr (\<lambda>p kh. kh(p := new)) ptrs f |> g
= foldr (\<lambda>p kh. kh(p := (case new of Some x \<Rightarrow> g x | _ \<Rightarrow> None))) ptrs (f |> g)"
by (induct ptrs arbitrary: new; clarsimp split: option.splits)
lemma opt_map_Some_foldr_upd:
"(foldr (\<lambda>p kh. kh(p := new)) ptrs f) ||> g
= foldr (\<lambda>p kh. kh(p := (case new of Some x \<Rightarrow> Some (g x) | _ \<Rightarrow> None))) ptrs (f ||> g)"
by (induct ptrs arbitrary: new; clarsimp split: option.splits)
"foldr (\<lambda>p kh. kh(p := new)) ptrs f ||> g
= foldr (\<lambda>p kh. kh(p := map_option g new)) ptrs (f ||> g)"
by (induct ptrs arbitrary: new; clarsimp simp: map_option_case split: option.splits)
lemmas opt_map_foldr_upd_simps
= opt_map_foldr_upd opt_map_Some_foldr_upd
lemmas opt_map_foldr_upd_simps = opt_map_foldr_upd opt_map_Some_foldr_upd
lemma opt_map_Some_comp[simp]:
"f ||> g ||> h = f ||> h o g"
@ -138,8 +146,7 @@ lemma opt_map_Some_eta_fold:
by (simp add: o_def)
lemma case_opt_map_distrib:
"((\<lambda>s. case_option None g (f s)) |> h)
= ((\<lambda>s. case_option None (g |> h) (f s)))"
"(\<lambda>s. case_option None g (f s)) |> h = (\<lambda>s. case_option None (g |> h) (f s))"
by (fastforce simp: opt_map_def split: option.splits)
lemma opt_map_apply_left_eq:
@ -152,20 +159,14 @@ declare None_upd_eq[simp]
lemma "\<lbrakk> (f |> g) x = None; g v = None \<rbrakk> \<Longrightarrow> f(x \<mapsto> v) |> g = f |> g"
by simp
definition map_set :: "('a \<Rightarrow> 'b set option) \<Rightarrow> 'a \<Rightarrow> 'b set" where
"map_set f \<equiv> case_option {} id \<circ> f"
(* opt_pred *)
definition opt_pred :: "('a \<Rightarrow> bool) \<Rightarrow> ('b \<Rightarrow> 'a option) \<Rightarrow> ('b \<Rightarrow> bool)" (infixl "|<" 55) where
"P |< proj \<equiv> (\<lambda>x. case_option False P (proj x))"
subsection \<open>Lemmas for @{const opt_pred}\<close>
lemma opt_pred_conj:
"((P1 |< hp) p \<and> (P2 |< hp) p) = (((P1 and P2) |< hp) p)"
"((P |< hp) p \<and> (Q |< hp) p) = ((P and Q) |< hp) p"
by (fastforce simp: pred_conj_def opt_pred_def split: option.splits)
lemma opt_pred_disj:
"((P1 |< hp) p \<or> (P2 |< hp) p) = (((P1 or P2) |< hp) p)"
"((P |< hp) p \<or> (Q |< hp) p) = ((P or Q) |< hp) p"
by (fastforce simp: pred_disj_def opt_pred_def split: option.splits)
lemma in_opt_pred:
@ -179,40 +180,38 @@ lemma opt_predE:
by (blast dest: opt_predD)
lemma opt_pred_unfold_map:
"(P |< (f |> g)) = ((P |< g) |< f)"
"P |< (f |> g) = P |< g |< f"
by (fastforce simp: opt_map_def in_opt_pred split: option.splits)
lemma opt_pred_unfold_proj:
"(P |< (f ||> g))= (P o g |< f)"
"P |< (f ||> g) = P o g |< f"
by (clarsimp simp: opt_map_def opt_pred_def split: option.splits)
(* This rule is useful when fun_upd_apply is not in the simp set: *)
lemma opt_pred_proj_upd_eq[simp]:
"(P |< proj (p \<mapsto> v)) p = P v"
by (simp add: in_opt_pred)
(* obind, etc. *)
section \<open>The Reader Option Monad\<close>
definition
obind :: "('s,'a) lookup \<Rightarrow> ('a \<Rightarrow> ('s,'b) lookup) \<Rightarrow> ('s,'b) lookup" (infixl "|>>" 53)
where
definition obind :: "('s,'a) lookup \<Rightarrow> ('a \<Rightarrow> ('s,'b) lookup) \<Rightarrow> ('s,'b) lookup" (infixl "|>>" 53)
where
"f |>> g \<equiv> \<lambda>s. case f s of None \<Rightarrow> None | Some x \<Rightarrow> g x s"
(* Enable "do { .. }" syntax *)
adhoc_overloading
Monad_Syntax.bind obind
definition
definition ofail :: "('s, 'a) lookup" where
"ofail = K None"
definition
definition oreturn :: "'a \<Rightarrow> ('s, 'a) lookup" where
"oreturn = K o Some"
definition
definition oassert :: "bool \<Rightarrow> ('s, unit) lookup" where
"oassert P \<equiv> if P then oreturn () else ofail"
definition
definition oassert_opt :: "'a option \<Rightarrow> ('s, 'a) lookup" where
"oassert_opt r \<equiv> case r of None \<Rightarrow> ofail | Some x \<Rightarrow> oreturn x"
definition oapply :: "'a \<Rightarrow> ('a \<Rightarrow> 'b option) \<Rightarrow> 'b option" where
@ -231,19 +230,18 @@ definition owhen :: "bool \<Rightarrow> ('s, unit) lookup \<Rightarrow> ('s, uni
"owhen P f \<equiv> if P then f else oreturn ()"
(* Reader monad interface: *)
abbreviation (input)
abbreviation (input) ask :: "('s, 's) lookup" where
"ask \<equiv> Some"
definition
definition asks :: "('s \<Rightarrow> 'a) \<Rightarrow> ('s, 'a) lookup" where
"asks f = do { v <- ask; oreturn (f v) }"
abbreviation
abbreviation ogets :: "('s \<Rightarrow> 'a) \<Rightarrow> ('s, 'a) lookup" where
"ogets \<equiv> asks"
text \<open>
If the result can be an exception.
Corresponding bindE would be analogous to lifting in NonDetMonad.
\<close>
Integration with exception monad.
Corresponding bindE would be analogous to lifting in NonDetMonad.\<close>
definition
"oreturnOk x = K (Some (Inr x))"
@ -260,11 +258,15 @@ definition
definition
"oskip \<equiv> oreturn ()"
text \<open>Monad laws\<close>
lemma oreturn_bind [simp]: "(oreturn x |>> f) = f x"
subsection \<open>Monad laws\<close>
lemma oreturn_bind[simp]:
"(oreturn x |>> f) = f x"
by (auto simp add: oreturn_def obind_def K_def)
lemma obind_return [simp]: "(m |>> oreturn) = m"
lemma obind_return[simp]:
"(m |>> oreturn) = m"
by (auto simp add: oreturn_def obind_def K_def split: option.splits)
lemma obind_assoc:
@ -272,7 +274,7 @@ lemma obind_assoc:
by (auto simp add: oreturn_def obind_def K_def split: option.splits)
text \<open>Binding fail\<close>
subsection \<open>Binding and fail\<close>
lemma obind_fail [simp]:
"f |>> (\<lambda>_. ofail) = ofail"
@ -283,53 +285,53 @@ lemma ofail_bind [simp]:
by (auto simp add: ofail_def obind_def K_def split: option.splits)
subsection \<open>Function package setup\<close>
text \<open>Function package setup\<close>
lemma opt_bind_cong [fundef_cong]:
lemma opt_bind_cong[fundef_cong]:
"\<lbrakk> f = f'; \<And>v s. f' s = Some v \<Longrightarrow> g v s = g' v s \<rbrakk> \<Longrightarrow> f |>> g = f' |>> g'"
by (rule ext) (simp add: obind_def split: option.splits)
lemma opt_bind_cong_apply [fundef_cong]:
lemma opt_bind_cong_apply[fundef_cong]:
"\<lbrakk> f s = f' s; \<And>v. f' s = Some v \<Longrightarrow> g v s = g' v s \<rbrakk> \<Longrightarrow> (f |>> g) s = (f' |>> g') s"
by (simp add: obind_def split: option.splits)
lemma oassert_bind_cong [fundef_cong]:
lemma oassert_bind_cong[fundef_cong]:
"\<lbrakk> P = P'; P' \<Longrightarrow> m = m' \<rbrakk> \<Longrightarrow> oassert P |>> m = oassert P' |>> m'"
by (auto simp: oassert_def)
lemma oassert_bind_cong_apply [fundef_cong]:
lemma oassert_bind_cong_apply[fundef_cong]:
"\<lbrakk> P = P'; P' \<Longrightarrow> m () s = m' () s \<rbrakk> \<Longrightarrow> (oassert P |>> m) s = (oassert P' |>> m') s"
by (auto simp: oassert_def)
lemma oreturn_bind_cong [fundef_cong]:
lemma oreturn_bind_cong[fundef_cong]:
"\<lbrakk> x = x'; m x' = m' x' \<rbrakk> \<Longrightarrow> oreturn x |>> m = oreturn x' |>> m'"
by simp
lemma oreturn_bind_cong_apply [fundef_cong]:
lemma oreturn_bind_cong_apply[fundef_cong]:
"\<lbrakk> x = x'; m x' s = m' x' s \<rbrakk> \<Longrightarrow> (oreturn x |>> m) s = (oreturn x' |>> m') s"
by simp
lemma oreturn_bind_cong2 [fundef_cong]:
lemma oreturn_bind_cong2[fundef_cong]:
"\<lbrakk> x = x'; m x' = m' x' \<rbrakk> \<Longrightarrow> (oreturn $ x) |>> m = (oreturn $ x') |>> m'"
by simp
lemma oreturn_bind_cong2_apply [fundef_cong]:
lemma oreturn_bind_cong2_apply[fundef_cong]:
"\<lbrakk> x = x'; m x' s = m' x' s \<rbrakk> \<Longrightarrow> ((oreturn $ x) |>> m) s = ((oreturn $ x') |>> m') s"
by simp
lemma ocondition_cong [fundef_cong]:
lemma ocondition_cong[fundef_cong]:
"\<lbrakk>c = c'; \<And>s. c' s \<Longrightarrow> l s = l' s; \<And>s. \<not>c' s \<Longrightarrow> r s = r' s\<rbrakk>
\<Longrightarrow> ocondition c l r = ocondition c' l' r'"
by (auto simp: ocondition_def)
text \<open>Decomposition\<close>
subsection \<open>Decomposition\<close>
lemma ocondition_K_true [simp]:
lemma ocondition_K_true[simp]:
"ocondition (\<lambda>_. True) T F = T"
by (simp add: ocondition_def)
lemma ocondition_K_false [simp]:
lemma ocondition_K_false[simp]:
"ocondition (\<lambda>_. False) T F = F"
by (simp add: ocondition_def)
@ -353,7 +355,7 @@ lemma oreturnE:
"\<lbrakk>oreturn x s = Some v; v = x \<Longrightarrow> P\<rbrakk> \<Longrightarrow> P"
by simp
lemma in_ofail [simp]:
lemma in_ofail[simp]:
"ofail s \<noteq> Some v"
by (auto simp: ofail_def K_def)
@ -361,15 +363,15 @@ lemma ofailE:
"ofail s = Some v \<Longrightarrow> P"
by simp
lemma in_oassert_eq [simp]:
lemma in_oassert_eq[simp]:
"(oassert P s = Some v) = P"
by (simp add: oassert_def)
lemma oassert_True [simp]:
lemma oassert_True[simp]:
"oassert True = oreturn ()"
by (simp add: oassert_def)
lemma oassert_False [simp]:
lemma oassert_False[simp]:
"oassert False = ofail"
by (simp add: oassert_def)
@ -398,11 +400,10 @@ lemma obind_eqI_full:
(clarsimp simp: obind_def split: option.splits)
lemma obindE:
"\<lbrakk> (f |>> g) s = Some v;
\<And>v'. \<lbrakk>f s = Some v'; g v' s = Some v\<rbrakk> \<Longrightarrow> P\<rbrakk> \<Longrightarrow> P"
"\<lbrakk> (f |>> g) s = Some v; \<And>v'. \<lbrakk>f s = Some v'; g v' s = Some v\<rbrakk> \<Longrightarrow> P\<rbrakk> \<Longrightarrow> P"
by (auto simp: in_obind_eq)
lemma in_othrow_eq [simp]:
lemma in_othrow_eq[simp]:
"(othrow e s = Some v) = (v = Inl e)"
by (auto simp: othrow_def K_def)
@ -410,7 +411,7 @@ lemma othrowE:
"\<lbrakk>othrow e s = Some v; v = Inl e \<Longrightarrow> P\<rbrakk> \<Longrightarrow> P"
by simp
lemma in_oreturnOk_eq [simp]:
lemma in_oreturnOk_eq[simp]:
"(oreturnOk x s = Some v) = (v = Inr x)"
by (auto simp: oreturnOk_def K_def)
@ -418,8 +419,7 @@ lemma oreturnOkE:
"\<lbrakk>oreturnOk x s = Some v; v = Inr x \<Longrightarrow> P\<rbrakk> \<Longrightarrow> P"
by simp
lemmas omonadE [elim!] =
obindE oreturnE ofailE othrowE oreturnOkE oassertE
lemmas omonadE[elim!] = obindE oreturnE ofailE othrowE oreturnOkE oassertE
lemma in_opt_map_Some_eq:
"((f ||> g) x = Some y) = (\<exists>v. f x = Some v \<and> g v = y)"
@ -481,10 +481,7 @@ text \<open>
(without passing through a state)
\<close>
inductive_set
option_while' :: "('a \<Rightarrow> bool) \<Rightarrow> ('a \<Rightarrow> 'a option) \<Rightarrow> 'a option rel"
for C B
where
inductive_set option_while' :: "('a \<Rightarrow> bool) \<Rightarrow> ('a \<Rightarrow> 'a option) \<Rightarrow> 'a option rel" for C B where
final: "\<not> C r \<Longrightarrow> (Some r, Some r) \<in> option_while' C B"
| fail: "\<lbrakk> C r; B r = None \<rbrakk> \<Longrightarrow> (Some r, None) \<in> option_while' C B"
| step: "\<lbrakk> C r; B r = Some r'; (Some r', sr'') \<in> option_while' C B \<rbrakk>
@ -498,10 +495,12 @@ definition
lemma option_while'_inj:
assumes "(s,s') \<in> option_while' C B" "(s, s'') \<in> option_while' C B"
shows "s' = s''"
using assms by (induct rule: option_while'.induct) (auto elim: option_while'.cases)
using assms
by (induct rule: option_while'.induct) (auto elim: option_while'.cases)
lemma option_while'_inj_step:
"\<lbrakk> C s; B s = Some s'; (Some s, t) \<in> option_while' C B ; (Some s', t') \<in> option_while' C B \<rbrakk> \<Longrightarrow> t = t'"
"\<lbrakk> C s; B s = Some s'; (Some s, t) \<in> option_while' C B ; (Some s', t') \<in> option_while' C B \<rbrakk>
\<Longrightarrow> t = t'"
by (metis option_while'.step option_while'_inj)
lemma option_while'_THE:
@ -516,9 +515,9 @@ lemma option_while_simps:
"(Some s, ss') \<in> option_while' C B \<Longrightarrow> option_while C B s = ss'"
using option_while'_inj_step[of C s B s']
by (auto simp: option_while_def option_while'_THE
intro: option_while'.intros
dest: option_while'_inj
elim: option_while'.cases)
intro: option_while'.intros
dest: option_while'_inj
elim: option_while'.cases)
lemma option_while_rule:
assumes "option_while C B s = Some s'"
@ -582,9 +581,7 @@ qed
section \<open>Lift @{term option_while} to the @{typ "('a,'s) lookup"} monad\<close>
definition
owhile :: "('a \<Rightarrow> 's \<Rightarrow> bool) \<Rightarrow> ('a \<Rightarrow> ('s,'a) lookup) \<Rightarrow> 'a \<Rightarrow> ('s,'a) lookup"
where
definition owhile :: "('a \<Rightarrow> 's \<Rightarrow> bool) \<Rightarrow> ('a \<Rightarrow> ('s,'a) lookup) \<Rightarrow> 'a \<Rightarrow> ('s,'a) lookup" where
"owhile c b a \<equiv> \<lambda>s. option_while (\<lambda>a. c a s) (\<lambda>a. b a s) a"
lemma owhile_unroll:
@ -593,7 +590,7 @@ lemma owhile_unroll:
option_while_simps
split: option.split)
text \<open>rule for terminating loops\<close>
text \<open>Rule for terminating loops\<close>
lemma owhile_rule:
assumes "I r s"