# Theory Code_Char

theory Code_Char
imports Char_ord
```(*  Title:      HOL/Library/Code_Char.thy
Author:     Florian Haftmann
*)

section ‹Code generation of pretty characters (and strings)›

theory Code_Char
imports Main Char_ord
begin

code_printing
type_constructor char ⇀
(SML) "char"
and (OCaml) "char"
and (Scala) "Char"

setup ‹
›

code_printing
constant integer_of_char ⇀
(SML) "!(IntInf.fromInt o Char.ord)"
and (OCaml) "Big'_int.big'_int'_of'_int (Char.code _)"
and (Scala) "BigInt(_.toInt)"
| constant char_of_integer ⇀
(SML) "!(Char.chr o IntInf.toInt)"
and (OCaml) "Char.chr (Big'_int.int'_of'_big'_int _)"
and (Haskell) "!(let chr k | (0 <= k && k < 256) = Prelude.toEnum k :: Prelude.Char in chr . Prelude.fromInteger)"
and (Scala) "!((k: BigInt) => if (BigInt(0) <= k && k < BigInt(256)) k.charValue else sys.error(\"character value out of range\"))"
| class_instance char :: equal ⇀
| constant "HOL.equal :: char ⇒ char ⇒ bool" ⇀
(SML) "!((_ : char) = _)"
and (OCaml) "!((_ : char) = _)"
and (Scala) infixl 5 "=="
| constant "Code_Evaluation.term_of :: char ⇒ term" ⇀
(Eval) "HOLogic.mk'_char/ (IntInf.fromInt/ (Char.ord/ _))"

code_reserved SML
char

code_reserved OCaml
char

code_reserved Scala
char

code_reserved SML String

code_printing
constant String.implode ⇀
(SML) "String.implode"
and (OCaml) "!(let l = _ in let res = String.create (List.length l) in let rec imp i = function | [] -> res | c :: l -> String.set res i c; imp (i + 1) l in imp 0 l)"
and (Scala) "!(\"\" ++/ _)"
| constant String.explode ⇀
(SML) "String.explode"
and (OCaml) "!(let s = _ in let rec exp i l = if i < 0 then l else exp (i - 1) (String.get s i :: l) in exp (String.length s - 1) [])"
and (Scala) "!(_.toList)"

code_printing
constant "Orderings.less_eq :: char ⇒ char ⇒ bool" ⇀
(SML) "!((_ : char) <= _)"
and (OCaml) "!((_ : char) <= _)"
and (Scala) infixl 4 "<="
and (Eval) infixl 6 "<="
| constant "Orderings.less :: char ⇒ char ⇒ bool" ⇀
(SML) "!((_ : char) < _)"
and (OCaml) "!((_ : char) < _)"
and (Scala) infixl 4 "<"
and (Eval) infixl 6 "<"
|  constant "Orderings.less_eq :: String.literal ⇒ String.literal ⇒ bool" ⇀
(SML) "!((_ : string) <= _)"
and (OCaml) "!((_ : string) <= _)"
― ‹Order operations for @{typ String.literal} work in Haskell only
if no type class instance needs to be generated, because String = [Char] in Haskell
and @{typ "char list"} need not have the same order as @{typ String.literal}.›