+ SCM s = make_music (ly_scm2string (type))->self_scm ();
+ unsmob_music (s)->immutable_property_alist_ = props;
+ scm_gc_unprotect_object (s);
+ return s;
+}
+
+// to do property args
+LY_DEFINE(ly_get_mutable_properties,
+ "ly:get-mutable-properties", 1, 0, 0, (SCM mus),
+"Return an alist signifying the mutable properties of @var{mus}.\n"
+"The immutable properties are not available; they should be initialized\n"
+"by the functions make-music-by-name function.\n"
+)
+{
+ Music *m = unsmob_music (mus);
+ SCM_ASSERT_TYPE(m, mus, SCM_ARG1, __FUNCTION__, "music");
+
+ return m->get_property_alist (true);
+}
+
+LY_DEFINE(ly_music_list_p,"music-list?", 1, 0, 0,
+ (SCM l),"Type predicate: return true if @var{l} is a list of music objects.")
+{
+ if (scm_list_p (l) != SCM_BOOL_T)
+ return SCM_BOOL_F;
+
+ while (gh_pair_p (l))