I&#39;d like to make one more argument in favor of my preference for more splitting of type classes.  IMO it&#39;s beneficial to split up classes to minimize unnecessary dependencies.  That is, while e.g. Monoid is very useful for containers, many container methods won&#39;t need it, e.g. &quot;elem&quot; or &quot;filter&quot;.  When you divide the type classes so only what&#39;s necessary is required, more data structures will be able to meet those criteria, which in turn makes the class more generally useful.<div>
<br></div><div>As an example, I have an extension to iteratee which uses raw buffers for holding data.  This allows it to operate in truly constant memory (only one allocation, deallocated when it&#39;s finished), which has resulted in performance benefits.  Unfortunately there is not a good Monoid instance for this type because appending buffers is not possible.  By introducing the NullPoint class (equivalent to mempty of Monoid) in iteratee, my raw buffer extension is able to re-use several iteratee functions which it would not be able to if I had require Monoid instead of NullPoint.</div>
<div><br></div><div>I think I&#39;ve made my arguments as well as I can, so I&#39;m going to be quiet now unless something new comes up.</div><div><br></div><div>Cheers,</div><div>John</div>