stdlib: Document maps:update_with/3,4

1 files changed, 36 insertions, 0 deletions

diff --git a/lib/stdlib/doc/src/maps.xml b/lib/stdlib/doc/src/maps.xml
index 97a7438890..bf45461e2b 100644
--- a/lib/stdlib/doc/src/maps.xml
+++ b/lib/stdlib/doc/src/maps.xml
@@ -381,6 +381,42 @@ error</code>
 			</desc>
 		</func>
 
+        <func>
+            <name name="update_with" arity="3"/>
+            <fsummary></fsummary>
+            <desc>
+                <p>Update a value in a <c><anno>Map1</anno></c> associated with <c><anno>Key</anno></c> by
+                    calling <c><anno>Fun</anno></c> on the old value to get a new value. An exception
+                    <c>{badkey,<anno>Key</anno>}</c> is generated if
+                    <c><anno>Key</anno></c> is not present in the map.</p>
+            <p>Example:</p>
+            <code type="none">
+> Map = #{"counter" => 1},
+  Fun = fun(V) -> V + 1 end,
+  maps:update_with("counter",Fun,Map).
+#{"counter" => 2}</code>
+			</desc>
+        </func>
+
+        <func>
+            <name name="update_with" arity="4"/>
+            <fsummary></fsummary>
+            <desc>
+                <p>Update a value in a <c><anno>Map1</anno></c> associated with <c><anno>Key</anno></c> by
+                    calling <c><anno>Fun</anno></c> on the old value to get a new value.
+                    If <c><anno>Key</anno></c> is not present
+                    in <c><anno>Map1</anno></c> then <c><anno>Init</anno></c> will be associated with
+                    <c><anno>Key</anno></c>.
+                </p>
+                <p>Example:</p>
+                <code type="none">
+> Map = #{"counter" => 1},
+  Fun = fun(V) -> V + 1 end,
+  maps:update_with("new counter",Fun,42,Map).
+#{"counter" => 1,"new counter" => 42}</code>
+            </desc>
+        </func>
+
 		<func>
 			<name name="values" arity="1"/>
 			<fsummary></fsummary>