Theory Multiquote

theory Multiquote
imports Main
(*  Title:      HOL/ex/Multiquote.thy
Author: Markus Wenzel, TU Muenchen
*)


header {* Multiple nested quotations and anti-quotations *}

theory Multiquote
imports Main
begin

text {*
Multiple nested quotations and anti-quotations -- basically a
generalized version of de-Bruijn representation.
*}


syntax
"_quote" :: "'b => ('a => 'b)" ("«_»" [0] 1000)
"_antiquote" :: "('a => 'b) => 'b" ("´_" [1000] 1000)

parse_translation {*
let
fun antiquote_tr i (Const (@{syntax_const "_antiquote"}, _) $
(t as Const (@{syntax_const "_antiquote"}, _) $ _)) = skip_antiquote_tr i t
| antiquote_tr i (Const (@{syntax_const "_antiquote"}, _) $ t) =
antiquote_tr i t $ Bound i
| antiquote_tr i (t $ u) = antiquote_tr i t $ antiquote_tr i u
| antiquote_tr i (Abs (x, T, t)) = Abs (x, T, antiquote_tr (i + 1) t)
| antiquote_tr _ a = a
and skip_antiquote_tr i ((c as Const (@{syntax_const "_antiquote"}, _)) $ t) =
c $ skip_antiquote_tr i t
| skip_antiquote_tr i t = antiquote_tr i t;

fun quote_tr [t] = Abs ("s", dummyT, antiquote_tr 0 (Term.incr_boundvars 1 t))
| quote_tr ts = raise TERM ("quote_tr", ts);
in [(@{syntax_const "_quote"}, K quote_tr)] end
*}


text {* basic examples *}
term "«a + b + c»"
term "«a + b + c + ´x + ´y + 1»"
term "«´(f w) + ´x»"
term "«f ´x ´y z»"

text {* advanced examples *}
term "««´´x + ´y»»"
term "««´´x + ´y» o ´f»"
term "«´(f o ´g)»"
term "««´´(f o ´g)»»"

end