I've created a ticket for this at <a href="http://hackage.haskell.org/trac/ghc/ticket/5787">http://hackage.haskell.org/trac/ghc/ticket/5787</a>. I've been having some issues with my local install but should put a patch up very soon.<div>
<br></div><div>Dan<br><div><br><div class="gmail_quote">On Mon, Dec 19, 2011 at 5:32 PM, Brent Yorgey <span dir="ltr"><<a href="mailto:byorgey@seas.upenn.edu">byorgey@seas.upenn.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="HOEnZb"><div class="h5">On Sat, Dec 17, 2011 at 01:37:35PM -0500, Daniel Peebles wrote:<br>
> I noticed that the ZipList newtype in Control.Applicative has no derived<br>
> instances at all. We can't show a ZipList, check it for equality, or do<br>
> anything to it except unpack it or treat it like an Applicative or Functor.<br>
><br>
> It seems fairly uncontroversial to suggest adding some instances for it,<br>
> but there are some minor questions to address: the obvious instances to add<br>
> might be Eq, Ord, Show, Read, and possibly Typeable and/or Data. Are there<br>
> any others I've missed? For the Read/Show instances, do we want manual ones<br>
> that don't use the verbose record-style output? Since it's just defined as<br>
> data ZipList a = ZipList { getZipList :: [a] } to get an easy accessor<br>
> (does anyone actually use getZipList as a field for record updates?), it<br>
> might be easier to write the projection manually and change the definition<br>
> to data ZipList a = ZipList [a] with a separate getZipList function, so the<br>
> deriving mechanism can give us a less noisy Show instance.<br>
<br>
</div></div>+1<br>
<span class="HOEnZb"><font color="#888888"><br>
-Brent<br>
</font></span><div class="HOEnZb"><div class="h5"><br>
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