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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Ah yes thanks.<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">As I suggest on that thread, I’d really like (someone) to try the “let’s make all evidence strict” idea. I think it could be a perf win all round.
<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">And if so, we’d get what David wants for free.<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-devs <ghc-devs-bounces@haskell.org>
<b>On Behalf Of </b>Ryan Scott<br>
<b>Sent:</b> 04 September 2018 17:15<br>
<b>To:</b> ghc-devs@haskell.org<br>
<b>Subject:</b> Re: Unpacking coercions<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">In case this wasn't clear, the context of this discussion in this GHC proposal [1], where David is trying to work around the fact that data types with existential Coercible constraints do not support unpacking. (By "unpacking", I mean putting
an {-# UNPACK #-} pragma in front of a field of that type does what you would expect.)<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">An example program which demonstrates the performance issue can be found here [2]. That comment concerns unboxed equality vs. boxed equality, but the same unpacking problems that affect boxed equality also affect Coercible.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Ryan S.<o:p></o:p></p>
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<p class="MsoNormal">-----<o:p></o:p></p>
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<p class="MsoNormal">[1] <a href="https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2Fpull%2F116&data=02%7C01%7Csimonpj%40microsoft.com%7C6503cdd836df4b6fc63808d61281ac30%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636716745484845080&sdata=fLDLZEX015AtZpM4qfXwJAo90dMk7YBLQXGYV7wcXQo%3D&reserved=0">
https://github.com/ghc-proposals/ghc-proposals/pull/116</a><o:p></o:p></p>
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<p class="MsoNormal">[2] <a href="https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2Fpull%2F116%23issuecomment-382346662&data=02%7C01%7Csimonpj%40microsoft.com%7C6503cdd836df4b6fc63808d61281ac30%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636716745484855092&sdata=dT3NAweHgwM%2FO7Ncjn4renyajsbkjU3UEMdgSIXaoz0%3D&reserved=0">
https://github.com/ghc-proposals/ghc-proposals/pull/116#issuecomment-382346662</a><o:p></o:p></p>
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