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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">My real question is this:<o:p></o:p></span></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo3"><span style="mso-fareast-language:EN-US">Who “owns” (as in: takes responsibility for) the GHC API?<o:p></o:p></span></li></ul>
<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">If no person, or no group of people, feels responsible for it, it’ll just grow in a disorganised fashion, which is why we are where we are.
<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" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
<span style="mso-fareast-language:EN-US">This discussion thread has focused mainly on stability, but there is more to it than that. For example:<o:p></o:p></span></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-top:6.0pt;margin-bottom:6.0pt;margin-left:0cm;mso-list:l0 level1 lfo3">
<span style="mso-fareast-language:EN-US">What kind of stability strikes a reasonable balance between developers and clients? Personally I think we should have
<o:p></o:p></span></li><ul style="margin-top:0cm" type="circle">
<li class="MsoListParagraph" style="margin-top:6.0pt;margin-bottom:6.0pt;margin-left:0cm;mso-list:l0 level2 lfo3">
<span style="mso-fareast-language:EN-US">A public API that is pretty stable, plus
<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-top:6.0pt;margin-bottom:6.0pt;margin-left:0cm;mso-list:l0 level2 lfo3">
<span style="mso-fareast-language:EN-US">Access to many internal GHC functions that change quite a bit.
<o:p></o:p></span></li></ul>
</ul>
<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:54.0pt">
<span style="mso-fareast-language:EN-US">Heavily used internal functions can get “blessed” and moved to the public API. Someone needs to do the blessing.<o:p></o:p></span></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-top:6.0pt;margin-bottom:6.0pt;margin-left:0cm;mso-list:l0 level1 lfo3">
<span style="mso-fareast-language:EN-US">What <b>is</b> a good public API? Where is it written down?<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-top:6.0pt;margin-bottom:6.0pt;margin-left:0cm;mso-list:l0 level1 lfo3">
<span style="mso-fareast-language:EN-US">What should GHC’s extensibility interface be like? Plugins and all that. What is a good design for (say) extensible interface files? What “hooks” should the GHC API afford? This is more than just “what arguments
should this function take”… it’s a matter of fundamental design. But design questions like this belong in the GHC-API world (not the core GHC world) because they are all about extension points.<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-top:6.0pt;margin-bottom:6.0pt;margin-left:0cm;mso-list:l0 level1 lfo3">
<span style="mso-fareast-language:EN-US">What is a good design for the plugins story more generally?<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I’d be quite content with a fairly informal group to act as the “owner”. But I think we would be better served if we
<i>had</i> such a group, </span><span lang="EN-US" style="mso-fareast-language:EN-US">and knew who they were.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" 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>Neil Mitchell<br>
<b>Sent:</b> 28 July 2020 09:19<br>
<b>To:</b> GHC developers <ghc-devs@haskell.org><br>
<b>Subject:</b> Re: How should we treat changes to the GHC API?<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">
The API changing regularly is a real hassle for people building on top of it. But, the people building on top of it are also some of the people changing it most. And the API isn't nice and beautiful as it stands, with lots of horrible work-arounds for downstream
users.<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">
I'd suggest letting people change the API freely. But avoid making bikeshed API changes (those which are minor improvements at best, and really just a different flavour of the same). And perhaps loop in heavy API users when removing functionality.<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">
<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">
Thanks, Neil<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">
<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">
On Tue, Jul 28, 2020 at 7:38 AM Daniel Trstenjak <<a href="mailto:daniel.trstenjak@gmail.com">daniel.trstenjak@gmail.com</a>> wrote:<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">
On Mon, Jul 27, 2020 at 08:57:12PM +0000, Richard Eisenberg wrote:<br>
> On the other hand, we could imagine a dedicated GHC API volunteer who<br>
> maintains the API on top of the shifting sands of GHC.<br>
<br>
Looking at other compilers that have been successful in having a stable<br>
API - like clang with the libclang - that's pretty much how they<br>
achieved it.<br>
<br>
The manpower of GHC devs is already pretty small, so putting another<br>
burden on them with a stable API won't work out that well.<br>
<br>
Also as a compiler dev you want to have the freedom to change your AST<br>
in the ways you need it, to incorporate new features. Having workarounds<br>
at this level to ensure API stability just seems to be the wrong place and<br>
will only increase the complexity in an already quite complex project.<br>
However a high level API on top of the AST is the perfect place for such<br>
special cases between different compiler versions.<br>
<br>
Greetings,<br>
Daniel<br>
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