src/HOL/Library/Code_Char_chr.thy
author wenzelm
Thu Feb 11 23:00:22 2010 +0100 (2010-02-11)
changeset 35115 446c5063e4fd
parent 32069 6d28bbd33e2c
child 37222 4d984bc33c66
permissions -rw-r--r--
modernized translations;
formal markup of @{syntax_const} and @{const_syntax};
minor tuning;
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(*  Title:      HOL/Library/Code_Char_chr.thy
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    Author:     Florian Haftmann
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*)
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header {* Code generation of pretty characters with character codes *}
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theory Code_Char_chr
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imports Char_nat Code_Char Code_Integer Main
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begin
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definition
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  "int_of_char = int o nat_of_char"
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lemma [code]:
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  "nat_of_char = nat o int_of_char"
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  unfolding int_of_char_def by (simp add: expand_fun_eq)
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definition
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  "char_of_int = char_of_nat o nat"
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lemma [code]:
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  "char_of_nat = char_of_int o int"
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  unfolding char_of_int_def by (simp add: expand_fun_eq)
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lemmas [code del] = char.recs char.cases char.size
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lemma [code, code_unfold]:
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  "char_rec f c = split f (nibble_pair_of_nat (nat_of_char c))"
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  by (cases c) (auto simp add: nibble_pair_of_nat_char)
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lemma [code, code_unfold]:
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  "char_case f c = split f (nibble_pair_of_nat (nat_of_char c))"
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  by (cases c) (auto simp add: nibble_pair_of_nat_char)
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lemma [code]:
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  "size (c\<Colon>char) = 0"
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  by (cases c) auto
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code_const int_of_char and char_of_int
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  (SML "!(IntInf.fromInt o Char.ord)" and "!(Char.chr o IntInf.toInt)")
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  (OCaml "Big'_int.big'_int'_of'_int (Char.code _)" and "Char.chr (Big'_int.int'_of'_big'_int _)")
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  (Haskell "toInteger (fromEnum (_ :: Char))" and "!(let chr k | k < 256 = toEnum k :: Char in chr . fromInteger)")
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end