<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
span.EmailStyle19
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;
mso-fareast-language:EN-US;}
.MsoPapDefault
{mso-style-type:export-only;
margin-top:6.0pt;
margin-right:0cm;
margin-bottom:6.0pt;
margin-left:0cm;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:469827755;
mso-list-template-ids:-1067176650;}
ol
{margin-bottom:0cm;}
ul
{margin-bottom:0cm;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-GB" link="blue" vlink="purple" style="word-wrap:break-word">
<div class="WordSection1">
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I’m content to follow Simon’s recommendation.<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">The proposal says<o:p></o:p></span></p>
<p style="margin-left:36.0pt">I propose to replace the primops that produce product-encoded sums with ones that produce proper unboxed sums.<o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">And it is nicer to have primops that are more explicit about their types, but of course GHC’s ultimate representation of an unboxed sum is precisely the same as the current primop’s one. So this
is purely an ergonomic improvement, and one that will be felt only by a small constituency. So the costs of the current setup are not heavy.<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">It’s a good proposal to have on file, in case it becomes more pressing some day.<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>
<div style="border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt">
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<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>Simon Marlow<br>
<b>Sent:</b> 08 March 2021 15:52<br>
<b>To:</b> Joachim Breitner <mail@joachim-breitner.de><br>
<b>Cc:</b> ghc-steering-committee@haskell.org<br>
<b>Subject:</b> [ghc-steering-committee] Recommendation: reject #367 (was: Re: Please review #367: Clarify primops using unboxed sums, Shepherd: Simon Marlow)<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
Committee,<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
<o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
Proposal #367 suggests using unboxed sums for the results of 7 (seven) primops that use sum types but currently have to encode those explicitly using `Int#`.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
<o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
<a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Ftreeowl%2Fghc-proposals%2Fblob%2Funboxed-sum-primops%2Fproposals%2F0000-unboxed-sum-primops.md&data=04%7C01%7Csimonpj%40microsoft.com%7C000703ba8b6f4771a5c108d8e24a21c6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637508156673797668%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=Nm7owDB1Mxxt5MG2JGe1%2Fw9t7FpDxBhU%2BppV09grIgg%3D&reserved=0">https://github.com/treeowl/ghc-proposals/blob/unboxed-sum-primops/proposals/0000-unboxed-sum-primops.md</a><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
<o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
The proposal is arguably the right thing, however I'm suggesting we reject it for the following reasons:<o:p></o:p></p>
</div>
<div>
<ol start="1" type="1">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
The implementations of the primops would bake in the translation of unboxed sums. Right now our unboxed sum translation is defined in one place - CorePrep - but this proposal would leak it into the implementations of a few primops.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
Migration would entail adding a backwards-compatibility layer, with the associated complexity and risk of performance regressions.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
While the current situation is perhaps inelegant, it's not broken and it's easy to understand.<o:p></o:p></li></ol>
<div>
<p class="MsoNormal">Thoughts?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Simon<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<div>
<p class="MsoNormal">On Sun, 4 Oct 2020 at 22:14, Joachim Breitner <<a href="mailto:mail@joachim-breitner.de">mail@joachim-breitner.de</a>> wrote:<o:p></o:p></p>
</div>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm">
<p class="MsoNormal">Dear Committee,<br>
<br>
this is your secretary speaking:<br>
<br>
Clarify primops using unboxed sum<br>
has been proposed by David Feuer<br>
<a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2Fpull%2F367&data=04%7C01%7Csimonpj%40microsoft.com%7C000703ba8b6f4771a5c108d8e24a21c6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637508156673807671%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=VR%2F9%2BRcLdFCqGcmxuCqPseHbr2rTjBDcX6r6NwDDvBs%3D&reserved=0" target="_blank">https://github.com/ghc-proposals/ghc-proposals/pull/367</a><br>
<a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Ftreeowl%2Fghc-proposals%2Fblob%2Funboxed-sum-primops%2Fproposals%2F0000-unboxed-sum-primops.md&data=04%7C01%7Csimonpj%40microsoft.com%7C000703ba8b6f4771a5c108d8e24a21c6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637508156673807671%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=DRJrOd7m2X0sB1d9HdcdyHYUm7Z6HTuT0QHRB56FXFs%3D&reserved=0" target="_blank">https://github.com/treeowl/ghc-proposals/blob/unboxed-sum-primops/proposals/0000-unboxed-sum-primops.md</a><br>
<br>
I’ll propose Simon Marlow as the shepherd.<br>
<br>
Please guide us to a conclusion as outlined in <br>
<a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%23committee-process&data=04%7C01%7Csimonpj%40microsoft.com%7C000703ba8b6f4771a5c108d8e24a21c6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637508156673817669%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=D%2FI8%2BJNnqo8XTVWtptXntxmBRwYP2wxZVX8tNxlZCQA%3D&reserved=0" target="_blank">https://github.com/ghc-proposals/ghc-proposals#committee-process</a><br>
<br>
Thanks,<br>
Joachim<br>
-- <br>
Joachim Breitner<br>
<a href="mailto:mail@joachim-breitner.de" target="_blank">mail@joachim-breitner.de</a><br>
<a href="https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.joachim-breitner.de%2F&data=04%7C01%7Csimonpj%40microsoft.com%7C000703ba8b6f4771a5c108d8e24a21c6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637508156673827660%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=lHwIB62LfzP%2F6e0MoitU5jlOQivnuB%2FrBlCgE7NOhfk%3D&reserved=0" target="_blank">
http://www.joachim-breitner.de/</a><br>
<br>
<br>
_______________________________________________<br>
ghc-steering-committee mailing list<br>
<a href="mailto:ghc-steering-committee@haskell.org" target="_blank">ghc-steering-committee@haskell.org</a><br>
<a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.haskell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc-steering-committee&data=04%7C01%7Csimonpj%40microsoft.com%7C000703ba8b6f4771a5c108d8e24a21c6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637508156673837651%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=oRJy6pL6bv9ZN6Q28ybaOHHMJE4yb9ieW0goPBHU4iw%3D&reserved=0" target="_blank">https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee</a><o:p></o:p></p>
</blockquote>
</div>
</div>
</div>
</div>
</body>
</html>