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<p class="MsoNormal" style="margin-left:36.0pt">I’ve found as a surprise that several members of the Committee have voted against, or even marked as dangerous, the DeriveAnyClass extension. Given that I am a great fan of it, I would like to open the debate
about the particular extension.<o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I’m a great fan of Template Haskell, but I didn’t put it in the “on by default” category.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">There are lots of “deriving” extensions. I treated them as a group, but you could perhaps argue that doing so isn’t right. Is there a reason to choose one over the others to be in the on-by-default
set? <o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> ghc-steering-committee <ghc-steering-committee-bounces@haskell.org>
<b>On Behalf Of </b>Alejandro Serrano Mena<br>
<b>Sent:</b> 30 November 2020 19:42<br>
<b>To:</b> ghc-steering-committee@haskell.org<br>
<b>Subject:</b> [ghc-steering-committee] GHC2021: DeriveAnyClass<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Dear all,<o:p></o:p></p>
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<p class="MsoNormal">I’ve found as a surprise that several members of the Committee have voted against, or even marked as dangerous, the DeriveAnyClass extension. Given that I am a great fan of it, I would like to open the debate about the particular extension.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">In my case, most of my uses are to derive ToJSON and FromJSON from the Aeson package. I find it very nice to be able to pack all the information about auto-derived instances in a small block, instead of including Eq and Show in the deriving
block, and then a few empty instance declarations below. This is definitely mainly a aesthetic reason.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The other reason for adoption is that it makes classes such as Eq or Show less “special”, so one does not have to explain to beginners that some classes can be derived in this way, some others in that other way, and so on. So my other reason
for inclusion would be a uniformity one.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Regards,<o:p></o:p></p>
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<p class="MsoNormal">Alejandro<o:p></o:p></p>
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