document use of ly_{car,cdr}

diff --git a/lily/include/lily-guile.hh b/lily/include/lily-guile.hh
index 3422089e9c50e043b884093d37600de8d42e14e3..02cdf7ddca2f61180961ff641fb7bb14742870ca 100644 (file)
--- a/lily/include/lily-guile.hh
+++ b/lily/include/lily-guile.hh
@@ -168,6 +168,10 @@ typedef SCM (*Scheme_function_2) (GUILE_ELLIPSIS);
 typedef SCM (*Scheme_function_3) (GUILE_ELLIPSIS);
 #endif
 
+
+/*
+  Inline these for performance reasons.
+ */
 #define scm_cdr ly_cdr
 #define scm_car ly_car