src/Pure/Syntax/syn_trans.ML

 (* type reflection *)
 
 fun type_tr (*"_TYPE"*) [ty] =
       const constrainC $ const "TYPE" $ (const "itself" $ ty)
   | type_tr (*"_TYPE"*) ts = raise TERM ("type_tr", ts);
+
+
+(* binds *)
+
+fun bind_ast_tr (*"_BIND"*) [Variable x] = Variable (string_of_vname (binding x, 0))
+  | bind_ast_tr (*"_BIND"*) asts = raise AST ("bind_ast_tr", asts);
 
 
 (* quote / antiquote *)
 
 fun quote_antiquote_tr quoteN antiquoteN name =

 (** pure_trfuns **)
 
 val pure_trfuns =
  ([("_appl", appl_ast_tr), ("_applC", applC_ast_tr),
    ("_lambda", lambda_ast_tr), ("_idtyp", idtyp_ast_tr),
-   ("_bigimpl", bigimpl_ast_tr)],
+   ("_bigimpl", bigimpl_ast_tr), ("_BIND", bind_ast_tr)],
   [("_abs", abs_tr), ("_aprop", aprop_tr), ("_ofclass", ofclass_tr),
    ("_TYPE", type_tr), ("_K", k_tr)],
   []: (string * (term list -> term)) list,
   [("_abs", abs_ast_tr'), ("_idts", idtyp_ast_tr' "_idts"),
    ("_pttrns", idtyp_ast_tr' "_pttrns"), ("==>", impl_ast_tr')]);