t is, the import of a variable <span 
class="pcrr7t-">x</span> does not
require that the datatypes and classes in the signature of <span 
class="pcrr7t-">x</span> be brought into the module along with <span 
class="pcrr7t-">x</span>
unless these entities are referenced by name in the user program. The Haskell system silently imports
any information that must accompany an entity for type checking or any other purposes. Such entities
need not even be explicitly exported: the following program is valid even th