On 11/1/06, <b class="gmail_sendername">Simon Peyton-Jones</b> <<a href="mailto:simonpj@microsoft.com" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">simonpj@microsoft.com</a>> wrote:<div><span class="gmail_quote">
</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
The thread about "stand-alone" deriving is long-ish now, so I have summarised the issues here:<br> <a href="http://haskell.org/haskellwiki/GHC/StandAloneDeriving" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
http://haskell.org/haskellwiki/GHC/StandAloneDeriving
</a></blockquote><div><br>I think it is difficult to discuss things via a Wiki. I tried to add my comments to the page and it took a lot of edits due to a collision with BrianH's edit. Plus, it is not clear to me how agreement is to be indicated. For example, I think that Brian H's idea really good. Basically, the syntax for instances and derived instances would be identical, but derived instances would just omit the "where" clause, while non-derived instances would need the "where" clause. For that to work, the rules for when a context is required need to be the same for derived and non-derived instances, which I also think is a good idea.
<br><br>It is a much better idea than my "derive instance" suggestion, and I no longer support it.<br><br>- Brian Smith<br><br></div></div>