Merge branch 'egil/maps-doc'

* egil/maps-doc:
  doc: Add Maps example for sequential programming
  doc: Mention map expressions and map guards
  doc: Add maps to reference manual
  edoc: Add map/0 as a new predefined type
  doc: Descripe Maps type syntax
  doc: Clearify language of user-defined attributes
  doc: Document Maps datatype in reference manual
  erts: Document map guard functions
  erts: Fix is_map/1 spec

1 files changed, 20 insertions, 0 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 7aaded200c..e7e9b218f2 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -1784,6 +1784,15 @@ os_prompt% </pre>
       </desc>
     </func>
     <func>
+      <name name="is_map" arity="1"/>
+      <fsummary>Check whether a term is a map</fsummary>
+      <desc>
+        <p>Returns <c>true</c> if <c><anno>Term</anno></c> is a map;
+          otherwise returns <c>false</c>.</p>
+        <p>Allowed in guard tests.</p>
+      </desc>
+    </func>
+    <func>
       <name name="is_number" arity="1"/>
       <fsummary>Check whether a term is a number</fsummary>
       <desc>
@@ -2220,6 +2229,17 @@ os_prompt% </pre>
       </desc>
     </func>
     <func>
+      <name name="map_size" arity="1"/>
+      <fsummary>Return the size of a map</fsummary>
+      <desc>
+        <p>Returns an integer which is the number of key-value pairs in <c><anno>Map</anno></c>.</p>
+        <pre>
+> <input>map_size(#{a=>1, b=>2, c=>3}).</input>
+3</pre>
+        <p>Allowed in guard tests.</p>
+      </desc>
+    </func>
+    <func>
       <name name="max" arity="2"/>
       <fsummary>Return the largest of two term</fsummary>
       <desc>