mention portray_clause/1 and listing/1

diff --git a/README.md b/README.md
index a25a560d5d4da3c41121b53da9c8f584c1e0593d..a48295c9568293a15791136adc1dc1c3ba2d7de5 100644 (file)
--- a/README.md
+++ b/README.md
@@ -350,7 +350,8 @@ The modules that ship with Scryer Prolog are also called
 * [`format`](src/prolog/lib/format.pl)
   The nonterminal `format_//2` is used to describe formatted output,
   arranging arguments according to a given format string.
-  The predicate `format/2` is provided for impure output.
+  The predicates `format/2`, `portray_clause/1` and `listing/1`
+  provide formatted *impure* output.
 * [`assoc`](src/prolog/lib/assoc.pl)
   providing `empty_assoc/1`, `get_assoc/3`, `put_assoc/4` etc.
   to manage elements in AVL trees which ensure