(* Title: HOL/Tools/numeral_syntax.ML ID: $Id: numeral_syntax.ML,v 1.20 2005/06/11 20:15:50 wenzelm Exp $ Author: Markus Wenzel, TU Muenchen Concrete syntax for generic numerals. Assumes consts and syntax of theory HOL/Numeral. *) signature NUMERAL_SYNTAX = sig val setup: (theory -> theory) list end; structure NumeralSyntax: NUMERAL_SYNTAX = struct (* bit strings *) (*we try to handle superfluous leading digits nicely*) fun prefix_len _ [] = 0 | prefix_len pred (x :: xs) = if pred x then 1 + prefix_len pred xs else 0; fun dest_bin_str tm = let val rev_digs = HOLogic.bin_of tm handle TERM _ => raise Match val (sign, zs) = (case rev rev_digs of ~1 :: bs => ("-", prefix_len (equal 1) bs) | bs => ("", prefix_len (equal 0) bs)); val i = HOLogic.int_of rev_digs; val num = IntInf.toString (IntInf.abs i); in if i = IntInf.fromInt 0 orelse i = IntInf.fromInt 1 then raise Match else sign ^ implode (replicate zs "0") ^ num end; (* translation of integer numeral tokens to and from bitstrings *) fun numeral_tr (*"_Numeral"*) [t as Const (str, _)] = (Syntax.const "Numeral.number_of" $ (HOLogic.mk_bin (valOf (IntInf.fromString str)))) | numeral_tr (*"_Numeral"*) ts = raise TERM ("numeral_tr", ts); fun numeral_tr' show_sorts (*"number_of"*) (Type ("fun", [_, T])) (t :: ts) = let val t' = Syntax.const "_Numeral" $ Syntax.free (dest_bin_str t) in if not (! show_types) andalso can Term.dest_Type T then t' else Syntax.const Syntax.constrainC $ t' $ Syntax.term_of_typ show_sorts T end | numeral_tr' _ (*"number_of"*) T (t :: ts) = if T = dummyT then Syntax.const "_Numeral" $ Syntax.free (dest_bin_str t) else raise Match | numeral_tr' _ (*"number_of"*) _ _ = raise Match; (* theory setup *) val setup = [Theory.hide_consts_i false ["Numeral.Pls", "Numeral.Min"], Theory.hide_consts_i false ["Numeral.bit.B0", "Numeral.bit.B1"], Theory.add_trfuns ([], [("_Numeral", numeral_tr)], [], []), Theory.add_trfunsT [("number_of", numeral_tr'), ("Numeral.number_of", numeral_tr')]]; end;