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<p class="MsoNormal"><span style="font-size:12.0pt">Because if e contains<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> …(case x of Foo p q -> e2)…<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">as a sub-expression, we’d like to simplify it.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Sorry that is not documented; please do add that to the comments in the source code.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><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-devs <ghc-devs-bounces@haskell.org>
<b>On Behalf Of </b>Matthew Pickering<br>
<b>Sent:</b> 11 May 2018 15:54<br>
<b>To:</b> GHC developers <ghc-devs@haskell.org><br>
<b>Subject:</b> Motivation for refineDefaultAlt<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
Hi all,<o:p></o:p></p>
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<o:p> </o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
Does anyone know the motivation for refineDefaultAlt?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
The comment states <br>
<br>
- -- | Refine the default alternative to a 'DataAlt', if there is a unique way to do so.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
OK - so the code transforms something like <o:p></o:p></p>
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case x of { DEFAULT -> e }<br>
===><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
case x of { Foo a1 a2 a3 -> e }<br>
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<br>
but why is this necessary or desirable? <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:12.0pt;margin-left:0cm">
Perhaps you know Simon (Jakobi)?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
Cheers,<o:p></o:p></p>
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<o:p> </o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
Matt<o:p></o:p></p>
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<o:p> </o:p></p>
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