src/HOL/Library/Code_Char_chr.thy
author huffman
Fri Mar 30 12:32:35 2012 +0200 (2012-03-30)
changeset 47220 52426c62b5d0
parent 39302 d7728f65b353
child 48431 6efff142bb54
permissions -rw-r--r--
replace lemmas eval_nat_numeral with a simpler reformulation
     1 (*  Title:      HOL/Library/Code_Char_chr.thy
     2     Author:     Florian Haftmann
     3 *)
     4 
     5 header {* Code generation of pretty characters with character codes *}
     6 
     7 theory Code_Char_chr
     8 imports Char_nat Code_Char Code_Integer Main
     9 begin
    10 
    11 definition
    12   "int_of_char = int o nat_of_char"
    13 
    14 lemma [code]:
    15   "nat_of_char = nat o int_of_char"
    16   unfolding int_of_char_def by (simp add: fun_eq_iff)
    17 
    18 definition
    19   "char_of_int = char_of_nat o nat"
    20 
    21 lemma [code]:
    22   "char_of_nat = char_of_int o int"
    23   unfolding char_of_int_def by (simp add: fun_eq_iff)
    24 
    25 code_const int_of_char and char_of_int
    26   (SML "!(IntInf.fromInt o Char.ord)" and "!(Char.chr o IntInf.toInt)")
    27   (OCaml "Big'_int.big'_int'_of'_int (Char.code _)" and "Char.chr (Big'_int.int'_of'_big'_int _)")
    28   (Haskell "toInteger (fromEnum (_ :: Char))" and "!(let chr k | (0 <= k && k < 256) = toEnum k :: Char in chr . fromInteger)")
    29   (Scala "BigInt(_.toInt)" and "!((k: BigInt) => if (BigInt(0) <= k && k < BigInt(256)) k.charValue else error(\"character value out of range\"))")
    30 
    31 end