* eval.c (dwim_s): New symbol variable.

(dwim_loc, op_dwim): New static functions.
(op_modplace): Support assignment to dwim forms
with the help of dwim_loc.
(expand_place): Handle dwim places.
(eval_init): Initialize dwim_s. Register dwim operator
in op_table.

* eval.h (dwim_s): Declared.

* lib.c (chr_str, chr_str_set): Allow negative indices to index
backwards from end of string.
(vecref, vecref_l): Allow negative indices to index from
rear of array.
(obj_print, obj_pprint): Render (dwim ...) forms as [...].

* parser.l: Peoduce new METABKT token type for @[,
and '[', ']' tokens.

* parser.y (METABKT): New token. %type declaration for '['.
(list): Support square-bracket style of list, translated
into dwim form.
(meta_expr): Support @[...] variant.
(yybadtoken): Handle METABKT in switch.

* txr.1: Documented [...] syntax and dwim operator.

* txr.vim: Updated.

1 files changed, 2 insertions, 0 deletions

diff --git a/eval.h b/eval.h
index 90eca613..a2f7e177 100644
--- a/eval.h
+++ b/eval.h
@@ -24,6 +24,8 @@
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+extern val dwim_s;
+
 val make_env(val fbindings, val vbindings, val up_env);
 val env_fbind(val env, val sym, val fun);
 val env_vbind(val env, val sym, val obj);