ss="keyword">functor</span> (<a href="MarshalledNullableDataNOTForComparison/argument-1-D/index.html">D</a> : <span class="keyword">sig</span> ... <span class="keyword">end</span>) <span>&#45;&gt;</span> <a href="index.html#module-type-Data">Data</a> <span class="keyword">with</span> <span class="keyword">type</span> <a href="MarshalledNullableDataNOTForComparison/index.html#type-t">t</a> = <span><a href="MarshalledNullableDataNOTForComparison/argument-1-D/index.html#type-t">D.t</a> option</span></code></dt