guimb: further improvements

* libmu_scm/mu_body.c (mu-body?): New function.
* libmu_scm/mu_mailbox.c (mu-mailbox?): New function.
* libmu_scm/mu_message.c (mu-message?): New function.
* libmu_scm/mu_mime.c (mu-mime?): New function.
* scheme/guimb.scmi (guimb-process-mailbox): guimb-message returns
a message to be appended to the output mailbox.

@@ -95,6 +95,15 @@ mu_scm_body_create (SCM msg, mu_body_t body)
 /* ************************************************************************* */
 /* Guile primitives */
 
+SCM_DEFINE_PUBLIC (scm_mu_body_p, "mu-body?", 1, 0, 0,
+		   (SCM scm),
+"Return @code{true} if @var{scm} is a Mailutils message body object.\n")
+#define FUNC_NAME s_scm_mu_body_p
+{
+  return mu_scm_is_body (scm);
+}
+#undef FUNC_NAME
+
 SCM_DEFINE_PUBLIC (scm_mu_body_read_line, "mu-body-read-line", 1, 0, 0,
 	    (SCM body), 
 	    "Read next line from the @var{body}.")

@@ -136,6 +136,15 @@ mu_scm_is_mailbox (SCM scm)
 /* ************************************************************************* */
 /* Guile primitives */
 
+SCM_DEFINE_PUBLIC (scm_mu_mailbox_p, "mu-mailbox?", 1, 0, 0,
+		   (SCM scm),
+"Return @code{true} if @var{scm} is a Mailutils mailbox.\n")
+#define FUNC_NAME s_scm_mu_mailbox_p
+{
+  return scm_from_bool (mu_scm_is_mailbox (scm));
+}
+#undef FUNC_NAME
+
 SCM_DEFINE_PUBLIC (scm_mu_mail_directory, "mu-mail-directory", 0, 1, 0,
 		   (SCM url), 
 "Do not use this function. Use mu-user-mailbox-url instead.")

@@ -175,6 +175,15 @@ mu_scm_is_message (SCM scm)
 /* ************************************************************************* */
 /* Guile primitives */
 
+SCM_DEFINE_PUBLIC (scm_mu_message_p, "mu-message?", 1, 0, 0,
+		   (SCM scm),
+"Return @code{true} if @var{scm} is a Mailutils message.\n")
+#define FUNC_NAME s_scm_mu_message_p
+{
+  return scm_from_bool (mu_scm_is_message (scm));
+}
+#undef FUNC_NAME
+
 SCM_DEFINE_PUBLIC (scm_mu_message_create, "mu-message-create", 0, 0, 0,
 		   (),
 		   "Creates an empty message.\n")

@@ -88,6 +88,15 @@ mu_scm_is_mime (SCM scm)
 /* ************************************************************************* */
 /* Guile primitives */
 
+SCM_DEFINE_PUBLIC (scm_mu_mime_p, "mu-mime?", 1, 0, 0,
+		   (SCM scm),
+"Return @code{true} if @var{scm} is a Mailutils MIME object.\n")
+#define FUNC_NAME s_scm_mu_mime_p
+{
+  return scm_from_bool (mu_scm_is_mime (scm));
+}
+#undef FUNC_NAME
+
 SCM_DEFINE_PUBLIC (scm_mu_mime_create, "mu-mime-create", 0, 2, 0,
 		   (SCM flags, SCM mesg),
 "Creates a new @acronym{MIME} object.  Both arguments are optional.\n"

@@ -49,22 +49,26 @@ exec ${GUILE-guile} -l $0 -c "(apply $main (list (command-line)))" "$@"
   (format #t "usage: guimb [OPTIONS] [MAILBOX [MAILBOX...]]
 guimb applies a scheme function to each message from a set of input mailboxes
 
-The following options stop argument processing, and pass all remaining
-arguments as the value of (command-line):
+The following options stop argument processing, and pass the remaining
+arguments to the guimb-getopt function, if it is defined in the module:
 
-  -c, --code=EXPR            execute given scheme expression
-  -s, --source=FILE          load Scheme module from FILE.scm
+  -c, --code=EXPR            execute given Scheme expression
+  -s, --source=MODNAME       load Scheme module MODNAME
 
-The following options do not affect further options parsing:
+The following options have the same effect, but do not affect further
+options parsing:
 
-  -e, --expression=EXPR      execute given scheme expression
-  -f, --file=FILE            load Scheme module from FILE.scm
+  -e, --expression=EXPR      execute given Scheme expression
+  -f, --file=MODNAME         load Scheme module MODNAME
+
+The module to be loaded is normally defined in a file named MODNAME.scm
+somewhere in your %load-path.
 
 Other options:
 
   -M, --mailbox=NAME         set output mailbox name
-  -u, --user[=NAME]          act as local MDA for user NAME (default - current
-                             user)
+  -u, --user[=NAME]          direct output to the system mailbox of the
+                             user NAME (default - current user)
   -r, --read-only            open mailbox in read-only mode
 
 Script arguments:
@@ -250,9 +254,9 @@ for any corresponding short options.
       (guimb-single-mailbox mbox)
       (let msg-loop ((msg (mu-mailbox-first-message mbox)))
 	(if (not (eof-object? msg))
-	    (begin
-	      (if (guimb-message msg)
-		  (mu-mailbox-append-message output-mailbox msg))
+	    (let ((x (guimb-message msg)))
+	      (if (mu-message? x)
+		  (mu-mailbox-append-message output-mailbox x))
 	      (msg-loop (mu-mailbox-next-message mbox)))))))
 
 (define (guimb cmdline)