src/HOL/Library/Code_Index.thy
author haftmann
Wed Jan 02 15:14:23 2008 +0100 (2008-01-02)
changeset 25767 852bce03412a
parent 25691 8f8d83af100a
child 25918 82dd239e0f65
permissions -rw-r--r--
index now a copy of nat rather than int
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(*  ID:         $Id$
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    Author:     Florian Haftmann, TU Muenchen
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*)
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header {* Type of indices *}
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theory Code_Index
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imports ATP_Linkup
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begin
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text {*
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  Indices are isomorphic to HOL @{typ nat} but
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  mapped to target-language builtin integers
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*}
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subsection {* Datatype of indices *}
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datatype index = index_of_nat nat
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lemmas [code func del] = index.recs index.cases
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primrec
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  nat_of_index :: "index \<Rightarrow> nat"
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where
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  "nat_of_index (index_of_nat k) = k"
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lemmas [code func del] = nat_of_index.simps
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lemma index_id [simp]:
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  "index_of_nat (nat_of_index n) = n"
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  by (cases n) simp_all
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lemma nat_of_index_inject [simp]:
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  "nat_of_index n = nat_of_index m \<longleftrightarrow> n = m"
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  by (cases n) auto
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lemma index:
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  "(\<And>n\<Colon>index. PROP P n) \<equiv> (\<And>n\<Colon>nat. PROP P (index_of_nat n))"
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proof
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  fix n :: nat
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  assume "\<And>n\<Colon>index. PROP P n"
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  then show "PROP P (index_of_nat n)" .
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next
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  fix n :: index
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  assume "\<And>n\<Colon>nat. PROP P (index_of_nat n)"
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  then have "PROP P (index_of_nat (nat_of_index n))" .
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  then show "PROP P n" by simp
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qed
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lemma [code func]: "size (n\<Colon>index) = 0"
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  by (cases n) simp_all
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subsection {* Indices as datatype of ints *}
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instantiation index :: number
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begin
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definition
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  "number_of = index_of_nat o nat"
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instance ..
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end
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code_datatype "number_of \<Colon> int \<Rightarrow> index"
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subsection {* Basic arithmetic *}
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instantiation index :: "{minus, ordered_semidom, Divides.div, linorder}"
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begin
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definition [simp, code func del]:
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  "(0\<Colon>index) = index_of_nat 0"
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lemma zero_index_code [code inline, code func]:
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  "(0\<Colon>index) = Numeral0"
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  by (simp add: number_of_index_def Pls_def)
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definition [simp, code func del]:
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  "(1\<Colon>index) = index_of_nat 1"
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lemma one_index_code [code inline, code func]:
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  "(1\<Colon>index) = Numeral1"
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  by (simp add: number_of_index_def Pls_def Bit_def)
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definition [simp, code func del]:
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  "n + m = index_of_nat (nat_of_index n + nat_of_index m)"
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lemma plus_index_code [code func]:
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  "index_of_nat n + index_of_nat m = index_of_nat (n + m)"
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  by simp
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definition [simp, code func del]:
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  "n - m = index_of_nat (nat_of_index n - nat_of_index m)"
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definition [simp, code func del]:
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  "n * m = index_of_nat (nat_of_index n * nat_of_index m)"
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lemma times_index_code [code func]:
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  "index_of_nat n * index_of_nat m = index_of_nat (n * m)"
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  by simp
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definition [simp, code func del]:
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  "n div m = index_of_nat (nat_of_index n div nat_of_index m)"
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definition [simp, code func del]:
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  "n mod m = index_of_nat (nat_of_index n mod nat_of_index m)"
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lemma div_index_code [code func]:
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  "index_of_nat n div index_of_nat m = index_of_nat (n div m)"
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  by simp
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lemma mod_index_code [code func]:
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  "index_of_nat n mod index_of_nat m = index_of_nat (n mod m)"
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  by simp
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definition [simp, code func del]:
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  "n \<le> m \<longleftrightarrow> nat_of_index n \<le> nat_of_index m"
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definition [simp, code func del]:
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  "n < m \<longleftrightarrow> nat_of_index n < nat_of_index m"
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lemma less_eq_index_code [code func]:
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  "index_of_nat n \<le> index_of_nat m \<longleftrightarrow> n \<le> m"
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  by simp
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lemma less_index_code [code func]:
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  "index_of_nat n < index_of_nat m \<longleftrightarrow> n < m"
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  by simp
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instance by default (auto simp add: left_distrib index)
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end
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subsection {* ML interface *}
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ML {*
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structure Index =
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struct
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fun mk k = @{term index_of_nat} $ HOLogic.mk_number @{typ index} k;
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end;
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*}
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subsection {* Code serialization *}
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text {* Pecularity for operations with potentially negative result *}
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definition
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  minus_index' :: "index \<Rightarrow> index \<Rightarrow> index"
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where
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  [code func del]: "minus_index' = op -"
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lemma minus_index_code [code func]:
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  "n - m = (let q = minus_index' n m
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    in if q < 0 then 0 else q)"
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  by (simp add: minus_index'_def Let_def)
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text {* Implementation of indices by bounded integers *}
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code_type index
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  (SML "int")
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  (OCaml "int")
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  (Haskell "Integer")
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code_instance index :: eq
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  (Haskell -)
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setup {*
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  fold (fn target => CodeTarget.add_pretty_numeral target true
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    @{const_name number_index_inst.number_of_index}
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    @{const_name Numeral.B0} @{const_name Numeral.B1}
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    @{const_name Numeral.Pls} @{const_name Numeral.Min}
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    @{const_name Numeral.Bit}
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  ) ["SML", "OCaml", "Haskell"]
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*}
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code_reserved SML int
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code_reserved OCaml int
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code_const "op + \<Colon> index \<Rightarrow> index \<Rightarrow> index"
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  (SML "Int.+ ((_), (_))")
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  (OCaml "Pervasives.+")
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  (Haskell infixl 6 "+")
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code_const "minus_index' \<Colon> index \<Rightarrow> index \<Rightarrow> index"
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  (SML "Int.- ((_), (_))")
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  (OCaml "Pervasives.-")
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  (Haskell infixl 6 "-")
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code_const "op * \<Colon> index \<Rightarrow> index \<Rightarrow> index"
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  (SML "Int.* ((_), (_))")
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  (OCaml "Pervasives.*")
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  (Haskell infixl 7 "*")
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code_const "op = \<Colon> index \<Rightarrow> index \<Rightarrow> bool"
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  (SML "!((_ : Int.int) = _)")
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  (OCaml "!((_ : Pervasives.int) = _)")
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  (Haskell infixl 4 "==")
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code_const "op \<le> \<Colon> index \<Rightarrow> index \<Rightarrow> bool"
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  (SML "Int.<= ((_), (_))")
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  (OCaml "!((_ : Pervasives.int) <= _)")
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  (Haskell infix 4 "<=")
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code_const "op < \<Colon> index \<Rightarrow> index \<Rightarrow> bool"
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  (SML "Int.< ((_), (_))")
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  (OCaml "!((_ : Pervasives.int) < _)")
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  (Haskell infix 4 "<")
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code_const "op div \<Colon> index \<Rightarrow> index \<Rightarrow> index"
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  (SML "IntInf.div ((_), (_))")
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  (OCaml "Big'_int.div'_big'_int")
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  (Haskell "div")
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code_const "op mod \<Colon> index \<Rightarrow> index \<Rightarrow> index"
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  (SML "IntInf.mod ((_), (_))")
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  (OCaml "Big'_int.mod'_big'_int")
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  (Haskell "mod")
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code_reserved SML Int
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code_reserved OCaml Pervasives
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end