<a href="#Interface_types">interface type</a> <code>comparable</code>
denotes the set of all non-interface types that are
<a href="#Comparison_operators">strictly comparable</a>
[<a href="#Go_1.18">Go 1.18</a>].
</p>

<p>
Even though interfaces that are not type parameters are <a href="#Comparison_operators">comparable</a>,
they are not strictly comparable and therefore they do not implement <code>comparable</code>.

The value of an uninitialized map is <code>nil</code>.
</p>

<pre class="ebnf">
MapType     = "map" "[" KeyType "]" ElementType .
KeyType     = Type .
</pre>

<p>
The <a href="#Comparison_operators">comparison operators</a>
<code>==</code> and <code>!=</code> must be fully defined
for operands of the key type; thus the key type must not be a function, map, or
slice.
If the key type is an interface type, these