
haftmann@29815: (* Author: Florian Haftmann, TU Muenchen *)
haftmann@24999: 
haftmann@24999: header {* Type of indices *}
haftmann@24999: 
haftmann@24999: theory Code_Index
haftmann@30663: imports Main
haftmann@24999: begin
haftmann@24999: 
haftmann@24999: text {*
haftmann@25767:   Indices are isomorphic to HOL @{typ nat} but
haftmann@27104:   mapped to target-language builtin integers.
haftmann@24999: *}
haftmann@24999: 
haftmann@24999: subsection {* Datatype of indices *}
haftmann@24999: 
haftmann@29815: typedef (open) index = "UNIV \<Colon> nat set"
haftmann@29815:   morphisms nat_of of_nat by rule
haftmann@24999: 
haftmann@29815: lemma of_nat_nat_of [simp]:
haftmann@29815:   "of_nat (nat_of k) = k"
haftmann@29815:   by (rule nat_of_inverse)
haftmann@24999: 
haftmann@29815: lemma nat_of_of_nat [simp]:
haftmann@29815:   "nat_of (of_nat n) = n"
haftmann@29815:   by (rule of_nat_inverse) (rule UNIV_I)
haftmann@24999: 
haftmann@28708: lemma [measure_function]:
haftmann@29815:   "is_measure nat_of" by (rule is_measure_trivial)
haftmann@28708: 
haftmann@24999: lemma index:
haftmann@29815:   "(\<And>n\<Colon>index. PROP P n) \<equiv> (\<And>n\<Colon>nat. PROP P (of_nat n))"
haftmann@24999: proof
haftmann@25767:   fix n :: nat
haftmann@25767:   assume "\<And>n\<Colon>index. PROP P n"
haftmann@29815:   then show "PROP P (of_nat n)" .
haftmann@24999: next
haftmann@25767:   fix n :: index
haftmann@29815:   assume "\<And>n\<Colon>nat. PROP P (of_nat n)"
haftmann@29815:   then have "PROP P (of_nat (nat_of n))" .
haftmann@25767:   then show "PROP P n" by simp
haftmann@24999: qed
haftmann@24999: 
haftmann@26140: lemma index_case:
haftmann@29815:   assumes "\<And>n. k = of_nat n \<Longrightarrow> P"
haftmann@26140:   shows P
haftmann@29815:   by (rule assms [of "nat_of k"]) simp
haftmann@26140: 
wenzelm@26304: lemma index_induct_raw:
haftmann@29815:   assumes "\<And>n. P (of_nat n)"
haftmann@26140:   shows "P k"
haftmann@26140: proof -
haftmann@29815:   from assms have "P (of_nat (nat_of k))" .
haftmann@26140:   then show ?thesis by simp
haftmann@26140: qed
haftmann@26140: 
haftmann@29815: lemma nat_of_inject [simp]:
haftmann@29815:   "nat_of k = nat_of l \<longleftrightarrow> k = l"
haftmann@29815:   by (rule nat_of_inject)
haftmann@26140: 
haftmann@29815: lemma of_nat_inject [simp]:
haftmann@29815:   "of_nat n = of_nat m \<longleftrightarrow> n = m"
haftmann@29815:   by (rule of_nat_inject) (rule UNIV_I)+
haftmann@26140: 
haftmann@26140: instantiation index :: zero
haftmann@26140: begin
haftmann@26140: 
haftmann@28562: definition [simp, code del]:
haftmann@29815:   "0 = of_nat 0"
haftmann@26140: 
haftmann@26140: instance ..
haftmann@26140: 
haftmann@26140: end
haftmann@26140: 
haftmann@26140: definition [simp]:
haftmann@29815:   "Suc_index k = of_nat (Suc (nat_of k))"
haftmann@26140: 
haftmann@27104: rep_datatype "0 \<Colon> index" Suc_index
haftmann@26140: proof -
haftmann@27104:   fix P :: "index \<Rightarrow> bool"
haftmann@27104:   fix k :: index
haftmann@29815:   assume "P 0" then have init: "P (of_nat 0)" by simp
haftmann@26140:   assume "\<And>k. P k \<Longrightarrow> P (Suc_index k)"
haftmann@29815:     then have "\<And>n. P (of_nat n) \<Longrightarrow> P (Suc_index (of_nat n))" .
haftmann@29815:     then have step: "\<And>n. P (of_nat n) \<Longrightarrow> P (of_nat (Suc n))" by simp
haftmann@29815:   from init step have "P (of_nat (nat_of k))"
haftmann@29815:     by (induct "nat_of k") simp_all
haftmann@26140:   then show "P k" by simp
haftmann@27104: qed simp_all
haftmann@26140: 
haftmann@26140: declare index_case [case_names nat, cases type: index]
haftmann@27104: declare index.induct [case_names nat, induct type: index]
haftmann@26140: 
haftmann@30245: lemma index_decr [termination_simp]:
haftmann@30245:   "k \<noteq> Code_Index.of_nat 0 \<Longrightarrow> Code_Index.nat_of k - Suc 0 < Code_Index.nat_of k"
haftmann@30245:   by (cases k) simp
haftmann@30245: 
haftmann@30245: lemma [simp, code]:
haftmann@29815:   "index_size = nat_of"
haftmann@26140: proof (rule ext)
haftmann@26140:   fix k
haftmann@29815:   have "index_size k = nat_size (nat_of k)"
haftmann@26140:     by (induct k rule: index.induct) (simp_all del: zero_index_def Suc_index_def, simp_all)
haftmann@29815:   also have "nat_size (nat_of k) = nat_of k" by (induct "nat_of k") simp_all
haftmann@29815:   finally show "index_size k = nat_of k" .
haftmann@26140: qed
haftmann@26140: 
haftmann@30245: lemma [simp, code]:
haftmann@29815:   "size = nat_of"
haftmann@26140: proof (rule ext)
haftmann@26140:   fix k
haftmann@29815:   show "size k = nat_of k"
haftmann@26140:   by (induct k) (simp_all del: zero_index_def Suc_index_def, simp_all)
haftmann@26140: qed
haftmann@26140: 
haftmann@30245: lemmas [code del] = index.recs index.cases
haftmann@30245: 
haftmann@28562: lemma [code]:
haftmann@29815:   "eq_class.eq k l \<longleftrightarrow> eq_class.eq (nat_of k) (nat_of l)"
haftmann@28346:   by (cases k, cases l) (simp add: eq)
haftmann@24999: 
haftmann@28351: lemma [code nbe]:
haftmann@28351:   "eq_class.eq (k::index) k \<longleftrightarrow> True"
haftmann@28351:   by (rule HOL.eq_refl)
haftmann@28351: 
haftmann@24999: 
haftmann@25767: subsection {* Indices as datatype of ints *}
haftmann@25767: 
haftmann@25767: instantiation index :: number
haftmann@25767: begin
haftmann@24999: 
haftmann@25767: definition
haftmann@29815:   "number_of = of_nat o nat"
haftmann@25767: 
haftmann@25767: instance ..
haftmann@25767: 
haftmann@25767: end
haftmann@24999: 
haftmann@29815: lemma nat_of_number [simp]:
haftmann@29815:   "nat_of (number_of k) = number_of k"
haftmann@26264:   by (simp add: number_of_index_def nat_number_of_def number_of_is_id)
haftmann@26264: 
haftmann@24999: code_datatype "number_of \<Colon> int \<Rightarrow> index"
haftmann@24999: 
haftmann@24999: 
haftmann@24999: subsection {* Basic arithmetic *}
haftmann@24999: 
haftmann@30926: instantiation index :: "{minus, ordered_semidom, semiring_div, linorder}"
haftmann@25767: begin
haftmann@24999: 
haftmann@28562: definition [simp, code del]:
haftmann@29815:   "(1\<Colon>index) = of_nat 1"
haftmann@24999: 
haftmann@28562: definition [simp, code del]:
haftmann@29815:   "n + m = of_nat (nat_of n + nat_of m)"
haftmann@25767: 
haftmann@28562: definition [simp, code del]:
haftmann@29815:   "n - m = of_nat (nat_of n - nat_of m)"
haftmann@25767: 
haftmann@28562: definition [simp, code del]:
haftmann@29815:   "n * m = of_nat (nat_of n * nat_of m)"
haftmann@25767: 
haftmann@28562: definition [simp, code del]:
haftmann@29815:   "n div m = of_nat (nat_of n div nat_of m)"
haftmann@24999: 
haftmann@28562: definition [simp, code del]:
haftmann@29815:   "n mod m = of_nat (nat_of n mod nat_of m)"
haftmann@24999: 
haftmann@28562: definition [simp, code del]:
haftmann@29815:   "n \<le> m \<longleftrightarrow> nat_of n \<le> nat_of m"
haftmann@24999: 
haftmann@28562: definition [simp, code del]:
haftmann@29815:   "n < m \<longleftrightarrow> nat_of n < nat_of m"
haftmann@24999: 
haftmann@29815: instance proof
haftmann@30926: qed (auto simp add: index left_distrib div_mult_self1)
haftmann@28708: 
haftmann@28708: end
haftmann@28708: 
haftmann@28708: lemma zero_index_code [code inline, code]:
haftmann@28708:   "(0\<Colon>index) = Numeral0"
haftmann@28708:   by (simp add: number_of_index_def Pls_def)
haftmann@28708: lemma [code post]: "Numeral0 = (0\<Colon>index)"
haftmann@28708:   using zero_index_code ..
haftmann@28708: 
haftmann@28708: lemma one_index_code [code inline, code]:
haftmann@28708:   "(1\<Colon>index) = Numeral1"
haftmann@28708:   by (simp add: number_of_index_def Pls_def Bit1_def)
haftmann@28708: lemma [code post]: "Numeral1 = (1\<Colon>index)"
haftmann@28708:   using one_index_code ..
haftmann@28708: 
haftmann@28708: lemma plus_index_code [code nbe]:
haftmann@29815:   "of_nat n + of_nat m = of_nat (n + m)"
haftmann@28708:   by simp
haftmann@28708: 
haftmann@28708: definition subtract_index :: "index \<Rightarrow> index \<Rightarrow> index" where
haftmann@28708:   [simp, code del]: "subtract_index = op -"
haftmann@28708: 
haftmann@28708: lemma subtract_index_code [code nbe]:
haftmann@29815:   "subtract_index (of_nat n) (of_nat m) = of_nat (n - m)"
haftmann@28708:   by simp
haftmann@28708: 
haftmann@28708: lemma minus_index_code [code]:
haftmann@28708:   "n - m = subtract_index n m"
haftmann@28708:   by simp
haftmann@28708: 
haftmann@28708: lemma times_index_code [code nbe]:
haftmann@29815:   "of_nat n * of_nat m = of_nat (n * m)"
haftmann@28708:   by simp
haftmann@28708: 
haftmann@28708: lemma less_eq_index_code [code nbe]:
haftmann@29815:   "of_nat n \<le> of_nat m \<longleftrightarrow> n \<le> m"
haftmann@25767:   by simp
haftmann@24999: 
haftmann@28708: lemma less_index_code [code nbe]:
haftmann@29815:   "of_nat n < of_nat m \<longleftrightarrow> n < m"
haftmann@25767:   by simp
haftmann@24999: 
haftmann@26140: lemma Suc_index_minus_one: "Suc_index n - 1 = n" by simp
haftmann@26140: 
haftmann@29815: lemma of_nat_code [code]:
haftmann@29815:   "of_nat = Nat.of_nat"
haftmann@25918: proof
haftmann@25918:   fix n :: nat
haftmann@29815:   have "Nat.of_nat n = of_nat n"
haftmann@25918:     by (induct n) simp_all
haftmann@29815:   then show "of_nat n = Nat.of_nat n"
haftmann@25918:     by (rule sym)
haftmann@25918: qed
haftmann@25918: 
haftmann@29815: lemma index_not_eq_zero: "i \<noteq> of_nat 0 \<longleftrightarrow> i \<ge> 1"
haftmann@25928:   by (cases i) auto
haftmann@25928: 
haftmann@29815: definition nat_of_aux :: "index \<Rightarrow> nat \<Rightarrow> nat" where
haftmann@29815:   "nat_of_aux i n = nat_of i + n"
haftmann@25928: 
haftmann@29815: lemma nat_of_aux_code [code]:
haftmann@29815:   "nat_of_aux i n = (if i = 0 then n else nat_of_aux (i - 1) (Suc n))"
haftmann@29815:   by (auto simp add: nat_of_aux_def index_not_eq_zero)
haftmann@25928: 
haftmann@29815: lemma nat_of_code [code]:
haftmann@29815:   "nat_of i = nat_of_aux i 0"
haftmann@29815:   by (simp add: nat_of_aux_def)
haftmann@25918: 
haftmann@28708: definition div_mod_index ::  "index \<Rightarrow> index \<Rightarrow> index \<times> index" where
haftmann@28562:   [code del]: "div_mod_index n m = (n div m, n mod m)"
haftmann@26009: 
haftmann@28562: lemma [code]:
haftmann@26009:   "div_mod_index n m = (if m = 0 then (0, n) else (n div m, n mod m))"
haftmann@26009:   unfolding div_mod_index_def by auto
haftmann@26009: 
haftmann@28562: lemma [code]:
haftmann@26009:   "n div m = fst (div_mod_index n m)"
haftmann@26009:   unfolding div_mod_index_def by simp
haftmann@26009: 
haftmann@28562: lemma [code]:
haftmann@26009:   "n mod m = snd (div_mod_index n m)"
haftmann@26009:   unfolding div_mod_index_def by simp
haftmann@26009: 
haftmann@31192: definition int_of :: "index \<Rightarrow> int" where
haftmann@31192:   "int_of = Nat.of_nat o nat_of"
haftmann@28708: 
haftmann@31192: lemma int_of_code [code]:
haftmann@31192:   "int_of k = (if k = 0 then 0
haftmann@31192:     else (if k mod 2 = 0 then 2 * int_of (k div 2) else 2 * int_of (k div 2) + 1))"
haftmann@31192:   by (auto simp add: int_of_def mod_div_equality')
haftmann@28708: 
haftmann@31192: lemma (in term_syntax) term_of_index_code [code]:
haftmann@31192:   "Code_Eval.term_of k =
haftmann@31192:     Code_Eval.termify (number_of :: int \<Rightarrow> int) <\<cdot>> Code_Eval.term_of_num (2::index) k"
haftmann@31192:   by (simp only: term_of_anything)
haftmann@28708: 
haftmann@31192: hide (open) const of_nat nat_of int_of
haftmann@28708: 
haftmann@28708: 
haftmann@28228: subsection {* Code generator setup *}
haftmann@24999: 
haftmann@25767: text {* Implementation of indices by bounded integers *}
haftmann@25767: 
haftmann@24999: code_type index
haftmann@24999:   (SML "int")
haftmann@24999:   (OCaml "int")
haftmann@25967:   (Haskell "Int")
haftmann@24999: 
haftmann@24999: code_instance index :: eq
haftmann@24999:   (Haskell -)
haftmann@24999: 
haftmann@24999: setup {*
haftmann@25928:   fold (Numeral.add_code @{const_name number_index_inst.number_of_index}
haftmann@25928:     false false) ["SML", "OCaml", "Haskell"]
haftmann@24999: *}
haftmann@24999: 
haftmann@25918: code_reserved SML Int int
haftmann@25918: code_reserved OCaml Pervasives int
haftmann@24999: 
haftmann@24999: code_const "op + \<Colon> index \<Rightarrow> index \<Rightarrow> index"
haftmann@25928:   (SML "Int.+/ ((_),/ (_))")
haftmann@25967:   (OCaml "Pervasives.( + )")
haftmann@24999:   (Haskell infixl 6 "+")
haftmann@24999: 
haftmann@28708: code_const "subtract_index \<Colon> index \<Rightarrow> index \<Rightarrow> index"
haftmann@25918:   (SML "Int.max/ (_/ -/ _,/ 0 : int)")
haftmann@25918:   (OCaml "Pervasives.max/ (_/ -/ _)/ (0 : int) ")
haftmann@25918:   (Haskell "max/ (_/ -/ _)/ (0 :: Int)")
haftmann@24999: 
haftmann@24999: code_const "op * \<Colon> index \<Rightarrow> index \<Rightarrow> index"
haftmann@25928:   (SML "Int.*/ ((_),/ (_))")
haftmann@25967:   (OCaml "Pervasives.( * )")
haftmann@24999:   (Haskell infixl 7 "*")
haftmann@24999: 
haftmann@26009: code_const div_mod_index
haftmann@29823:   (SML "(fn n => fn m =>/ if m = 0/ then (0, n) else/ (n div m, n mod m))")
haftmann@29823:   (OCaml "(fun n -> fun m ->/ if m = 0/ then (0, n) else/ (n '/ m, n mod m))")
haftmann@26009:   (Haskell "divMod")
haftmann@25928: 
haftmann@28346: code_const "eq_class.eq \<Colon> index \<Rightarrow> index \<Rightarrow> bool"
haftmann@24999:   (SML "!((_ : Int.int) = _)")
haftmann@25967:   (OCaml "!((_ : int) = _)")
haftmann@24999:   (Haskell infixl 4 "==")
haftmann@24999: 
haftmann@24999: code_const "op \<le> \<Colon> index \<Rightarrow> index \<Rightarrow> bool"
haftmann@25928:   (SML "Int.<=/ ((_),/ (_))")
haftmann@25967:   (OCaml "!((_ : int) <= _)")
haftmann@24999:   (Haskell infix 4 "<=")
haftmann@24999: 
haftmann@24999: code_const "op < \<Colon> index \<Rightarrow> index \<Rightarrow> bool"
haftmann@25928:   (SML "Int.</ ((_),/ (_))")
haftmann@25967:   (OCaml "!((_ : int) < _)")
haftmann@24999:   (Haskell infix 4 "<")
haftmann@24999: 
haftmann@24999: end




