<div dir="ltr"><div>Sorry, it's a long read. I'd read previous iterations of the proposal, and the wiki page previously. But the current proposal is yet a different text, I didn't want to opine without a proper reading.</div><div><br></div><div>The proposal is long, but doesn't really make a lot of concrete design choices.</div><div><br></div><div>- Extend the name lookup in type syntax to lookup in the term namespace when the name is absent in the type namespace</div><div>- A syntactic form `type …` to switch to the type namespace in terms</div><div>- Extend the term syntax to be a superset of the type syntax.</div><div>- Dependent Haskell is to be (mostly) backward compatible<br></div><div><br></div><div>I think that's about it. The rest establishes terminology and serves mostly as documentation. And it does a pretty good job at it, I think.</div><div><br></div><div>The proposed changes seem reasonable.<br></div><div><br></div><div>The language, though, is sometimes interesting:</div><div><br></div><div>> By accepting this proposal, the committee reaffirms Haskell's status as
an evolving, forward-thinking language, excited to adopt new ideas.</div><div><br></div><div>> There remain a few individuals who appear to remain deeply unconvinced. However, these seem to
be a small minority. The reasons they are not convinced appear to be around lack of
understanding of the proposal/design and general worry about unintended consequences.
I have tried to address both of these, but I do not believe my efforts have been fully
successful.</div><div><br></div><div>This is really not helpful, I don't think that we want to merge the proposal with this sort of language in it.</div><div><br></div><div>I'd add that the following:<br></div><div><br></div><div>> Many industrial Haskellers came out of the woodwork to support this proposal.</div><div><br></div><div>is rather misleading, since there seem to have been just as many industrial Haskellers which came out opposed to the proposal.</div><div><br></div><div>---</div><div><br></div><div>In summary: I'm in favour of the proposal, as long as Section 5 (Effect and Interaction) and below, are cleaned of the politically charged language.<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, May 13, 2021 at 5:09 PM Simon Peyton Jones via ghc-steering-committee <<a href="mailto:ghc-steering-committee@haskell.org">ghc-steering-committee@haskell.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div style="overflow-wrap: break-word;" lang="EN-GB">
<div class="gmail-m_-1902739115598012204WordSection1">
<p class="MsoNormal">Friends<u></u><u></u></p>
<p class="MsoNormal">You have now had a month to review my recommendation below, to accept #378: support for dependent types.
<a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fgoldfirere%2Fghc-proposals%2Fblob%2Fdependent-types%2Fproposals%2F0000-dependent-type-design.rst&data=04%7C01%7Csimonpj%40microsoft.com%7Cc0e29b49960a43b4d7ee08d8fff24512%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637540763362468484%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=K1JBnklN2ztnUyibLJ%2Bv9q8%2BK%2Bg1Sf%2FHDGjwVmj25Mw%3D&reserved=0" target="_blank">
Here it is once more</a><u></u><u></u></p>
<p class="MsoNormal">I have heard <u></u><u></u></p>
<ul style="margin-top:0cm" type="disc">
<li class="gmail-m_-1902739115598012204MsoListParagraph" style="margin-left:0cm">Support: Joachim, Vitaly, Alejandro, Vlad (plus Richard and myself)<u></u><u></u></li><li class="gmail-m_-1902739115598012204MsoListParagraph" style="margin-left:0cm">Against: no one<u></u><u></u></li></ul>
<p class="MsoNormal">But that leaves <b>Tom, Eric, Arnaud, Cale, Simon M, and Iavor</b> who have not expressed an opinion. Please do!<u></u><u></u></p>
<p class="MsoNormal">Failing further feedback, I’ll accept on Tuesday next week.<u></u><u></u></p>
<p class="MsoNormal">There has been some further <a href="https://github.com/ghc-proposals/ghc-proposals/pull/378" target="_blank">
discussion on the pull request</a>, but I don’t think any fundamentally new points have come up. This is clearly a judgement call, but one I think we should make. Haskell has always been a research lab – that’s part of what makes it distinctive. I think
we can continue to celebrate that innovation. But see my email immediately below for what we are and are not accepting.<u></u><u></u></p>
<p class="MsoNormal">Simon<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<div style="border-color:currentcolor currentcolor currentcolor blue;border-style:none none none solid;border-width:medium medium medium 1.5pt;padding:0cm 0cm 0cm 4pt">
<div>
<div style="border-color:rgb(225,225,225) currentcolor currentcolor;border-style:solid none none;border-width:1pt medium medium;padding:3pt 0cm 0cm">
<p class="MsoNormal" style="margin:0cm"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>>
<br>
<b>Sent:</b> 15 April 2021 10:39<br>
<b>To:</b> <a href="mailto:ghc-steering-committee@haskell.org" target="_blank">ghc-steering-committee@haskell.org</a><br>
<b>Cc:</b> Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>><br>
<b>Subject:</b> Recommendation for #378: support the design for dependent types<u></u><u></u></span></p>
</div>
</div>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Dear GHC steering committee<u></u><u></u></p>
<p class="MsoNormal">OK Richard has now revised the “Design for Dependent Types” proposal, and has resubmitted it. As we asked, it now
<i>includes</i> the design sketch that constitutes the direction of travel advocated in the proposal, rather than merely
<i>referring</i> to it.<u></u><u></u></p>
<p class="MsoNormal"><a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fgoldfirere%2Fghc-proposals%2Fblob%2Fdependent-types%2Fproposals%2F0000-dependent-type-design.rst&data=04%7C01%7Csimonpj%40microsoft.com%7Cc0e29b49960a43b4d7ee08d8fff24512%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637540763362468484%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=K1JBnklN2ztnUyibLJ%2Bv9q8%2BK%2Bg1Sf%2FHDGjwVmj25Mw%3D&reserved=0" target="_blank">Here
it is once more</a><u></u><u></u></p>
<p class="MsoNormal">I propose acceptance.<u></u><u></u></p>
<p class="MsoNormal">Remember:<u></u><u></u></p>
<ul style="margin-top:0cm" type="disc">
<li class="gmail-m_-1902739115598012204MsoListParagraph" style="margin-left:2.5pt">We
<b>would not</b> be accepting every detail of the design in Section 4 – rather, we expect further specific proposals as we move in the direction described in the proposal. So we should not debate the fine print of Section 4.
<u></u><u></u></li><li class="gmail-m_-1902739115598012204MsoListParagraph" style="margin-left:2.5pt">We
<b>would</b> be accepting that the proposal describes a direction of travel that we are happy with. That in turn gives people the confidence to invest efforts in those more detailed proposals. As the “Proposed change specification” says: “When evaluating
new proposals, the GHC committee would consider compatibility with the design sketch below. Generally speaking, new proposals should be forward-compatible with the design sketch; that is, the new features proposed would continue to be at home when surrounded
by other dependent-type features.”<u></u><u></u></li></ul>
<p class="MsoNormal">Any views? Questions of clarification or technical questions belong on the comment stream.<u></u><u></u></p>
<p class="MsoNormal">Thanks<u></u><u></u></p>
<p class="MsoNormal">Simon<u></u><u></u></p>
<div style="border-color:currentcolor currentcolor currentcolor blue;border-style:none none none solid;border-width:medium medium medium 1.5pt;padding:0cm 0cm 0cm 4pt">
<div>
<div style="border-color:rgb(225,225,225) currentcolor currentcolor;border-style:solid none none;border-width:1pt medium medium;padding:3pt 0cm 0cm">
<p class="MsoNormal" style="margin:0cm"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> ghc-steering-committee <<a href="mailto:ghc-steering-committee-bounces@haskell.org" target="_blank">ghc-steering-committee-bounces@haskell.org</a>>
<b>On Behalf Of </b>Simon Peyton Jones via ghc-steering-committee<br>
<b>Sent:</b> 06 April 2021 13:58<br>
<b>To:</b> <a href="mailto:ghc-steering-committee@haskell.org" target="_blank">ghc-steering-committee@haskell.org</a><br>
<b>Subject:</b> Re: [ghc-steering-committee] Recommendation for #378: support the design for dependent types<u></u><u></u></span></p>
</div>
</div>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Richard and I have discussed this.<u></u><u></u></p>
<p class="MsoNormal">We concluded that we’d put it back into “Needs revision” status. He’s going to expand it (substantially) to include
<i><a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc%2F-%2Fwikis%2Fdependent-haskell&data=04%7C01%7Csimonpj%40microsoft.com%7Cc0e29b49960a43b4d7ee08d8fff24512%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637540763362478476%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=C5Ywef9f5MK4jEc2XfmXeZ26YIdJeP0%2F%2BKfGdIhfkYA%3D&reserved=0" target="_blank">the
proposed design sketch of dependent types on the GHC wiki</a>. </i>Then he’ll resubmit in the hope of getting approval of the design in principle, subject to subsequent discussion of the fine detail.<u></u><u></u></p>
<p class="MsoNormal">Simon<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<div style="border-color:currentcolor currentcolor currentcolor blue;border-style:none none none solid;border-width:medium medium medium 1.5pt;padding:0cm 0cm 0cm 4pt">
<div>
<div style="border-color:rgb(225,225,225) currentcolor currentcolor;border-style:solid none none;border-width:1pt medium medium;padding:3pt 0cm 0cm">
<p class="MsoNormal" style="margin:0cm"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>>
<br>
<b>Sent:</b> 29 March 2021 13:17<br>
<b>To:</b> <a href="mailto:ghc-steering-committee@haskell.org" target="_blank">ghc-steering-committee@haskell.org</a><br>
<b>Cc:</b> Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>><br>
<b>Subject:</b> Recommendation for #378: support the design for dependent types<u></u><u></u></span></p>
</div>
</div>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Dear GHC Steering Committee<u></u><u></u></p>
<p class="MsoNormal">I’m recommending acceptance of Proposal #378: <a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2Fpull%2F378&data=04%7C01%7Csimonpj%40microsoft.com%7Cc0e29b49960a43b4d7ee08d8fff24512%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637540763362478476%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=%2Bf32VqzdL6HgiF436%2FGWPwBl09c1qo%2BAMbgPY6tJfSI%3D&reserved=0" target="_blank">
Support the design for dependent types</a><u></u><u></u></p>
<p class="MsoNormal">As you’ll see, there is a lot of useful context, but the payload is pretty simple<u></u><u></u></p>
<p style="margin-left:36pt"><i>When evaluating new proposals, the GHC committee would consider compatibility with
<a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc%2F-%2Fwikis%2Fdependent-haskell&data=04%7C01%7Csimonpj%40microsoft.com%7Cc0e29b49960a43b4d7ee08d8fff24512%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637540763362488470%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=1xOofIrHU3rP91mxYwvKnefFqCA5RBHCUUuKHqtdZlo%3D&reserved=0" target="_blank">
the proposed design sketch of dependent types on the GHC wiki</a>. Generally speaking, new proposals should be forward-compatible with the design sketch; that is, the new features proposed would continue to be at home when surrounded by other dependent-type
features.<u></u><u></u></i></p>
<p style="margin-left:36pt"><i>Of course, the committee remains free to revise the design sketch or to accept proposals that encroach upon it (i.e. contradicting this guidance), but such choices should be made explicitly.<u></u><u></u></i></p>
<p style="margin-left:36pt"><i>See also the committee's <a href="https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc-proposals%2Fghc-proposals%2F%23review-criteria&data=04%7C01%7Csimonpj%40microsoft.com%7Cc0e29b49960a43b4d7ee08d8fff24512%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637540763362488470%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=C%2B6VLghDD03q1Qwqwytrp75eAHQtPF%2FB1SveNIKrymA%3D&reserved=0" target="_blank">
Review Criteria</a>: put another way, this proposal says that we consider the design sketch alongside other features of today's Haskell when assessing a new proposal's fit with the language.<u></u><u></u></i></p>
<p style="margin-left:36pt"><i>Note that compatibility with dependent types is far from the only criterion the committee would use to evaluate a proposal. Other review criteria, such as learnability, clarity of error messages, performance, etc., remain just
as ever.<u></u><u></u></i></p>
<p class="MsoNormal">Any views? Let’s try to converge rapidly…. the proposal has been substantially refined by a lot of debate.<u></u><u></u></p>
<p class="MsoNormal">Simon<u></u><u></u></p>
</div>
</div>
</div>
</div>
</div>
_______________________________________________<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://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee" rel="noreferrer" target="_blank">https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee</a><br>
</blockquote></div>