* match.c (do_txeval): Lift an annoying restriction in the pattern

language's expression evaluator. Whereas TXR Lisp expressions can be
used int the pattern language, preceded by @, it was not possible
to evaluate TXR Lisp variables this way. So instead of @var,
some clumsy trick had to be used like @(identity var). This is not
necessary any more. Code like @(next @*stdin*) will now work.

* txr.1: Updated.

1 files changed, 4 insertions, 2 deletions

diff --git a/match.c b/match.c
index 23e96e9e..d46eced7 100644
--- a/match.c
+++ b/match.c
@@ -1432,8 +1432,10 @@ static val do_txeval(val spec, val form, val bindings, val allow_unbound)
       } else if (regexp(car(form))) {
         ret = form;
       } else if (first(form) == var_s) {
-        sem_error(spec, lit("metavariable @~s syntax cannot be used here"),
-                  second(form), nao);
+        uw_env_begin;
+        uw_set_match_context(cons(spec, bindings));
+        ret = eval(second(form), make_env(bindings, nil, nil), form);
+        uw_env_end;
       } else if (first(form) == expr_s) {
         uw_env_begin;
         uw_set_match_context(cons(spec, bindings));