<p>
A map is an unordered group of elements of one type, called the
-value type, indexed by a set of unique <i>keys</i> of another type,
+element type, indexed by a set of unique <i>keys</i> of another type,
called the key type.
A map value may be <code>nil</code>.
<pre class="ebnf">
MapType = "map" "[" KeyType "]" ElementType .
KeyType = Type .
-ValueType = Type .
</pre>
<p>
<pre class="ebnf">
ChannelType = Channel | SendChannel | RecvChannel .
-Channel = "chan" ValueType .
-SendChannel = "chan" "<-" ValueType .
-RecvChannel = "<-" "chan" ValueType .
+Channel = "chan" ElementType .
+SendChannel = "chan" "<-" ElementType .
+RecvChannel = "<-" "chan" ElementType .
</pre>
<p>