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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I’m still not getting it. GHC
<i>ignores</i> everything between {- and -}. Why would I need to produce a new GHC if someone wants to us {- WIMWAM blah -}?<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"> Brandon Allbery <allbery.b@gmail.com>
<br>
<b>Sent:</b> 16 October 2018 23:39<br>
<b>To:</b> Simon Peyton Jones <simonpj@microsoft.com><br>
<b>Cc:</b> Simon Marlow <marlowsd@gmail.com>; Neil Mitchell <ndmitchell@gmail.com>; ghc-devs@haskell.org Devs <ghc-devs@haskell.org><br>
<b>Subject:</b> Re: Treatment of unknown pragmas<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">One problem is you have to release a new ghc every time someone comes up with a new pragma-using tool that starts to catch on. Another is that the more of these you have, the more likely a typo will inadvertently match some tool you don't
even know about but ghc does.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Tue, Oct 16, 2018 at 6:34 PM Simon Peyton Jones via ghc-devs <<a href="mailto:ghc-devs@haskell.org">ghc-devs@haskell.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I’m still not understanding what’s wrong with<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">{- HLINT blah blah -}<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">GHC will ignore it. HLint can look at it. Simple.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I must be missing something obvious.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Simon<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> ghc-devs <<a href="mailto:ghc-devs-bounces@haskell.org" target="_blank">ghc-devs-bounces@haskell.org</a>>
<b>On Behalf Of </b>Simon Marlow<br>
<b>Sent:</b> 16 October 2018 21:44<br>
<b>To:</b> Neil Mitchell <<a href="mailto:ndmitchell@gmail.com" target="_blank">ndmitchell@gmail.com</a>><br>
<b>Cc:</b> ghc-devs <<a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a>><br>
<b>Subject:</b> Re: Treatment of unknown pragmas</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I suggested to Neil that he add the {-# HLINT #-} pragma to GHC. It seemed like the least worst option taking into account the various issues that have already been described in
this thread. I'm OK with adding HLINT; after all we already ignore OPTIONS_HADDOCK, OPTIONS_NHC98, a bunch of other OPTIONS, CFILES (a Hugs relic), and several more that GHC ignores.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">We can either<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">(a) not protect people from mistyped pragmas, or
<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">(b) protect people from mistyped pragma names, but then we have to bake in the set of known pragmas<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">We could choose to have a different convention for pragmas that GHC doesn't know about (as Ben suggests), but then of course we don't get any protection for mistyped pragma names
when using that convention.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Cheers<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Simon<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Tue, 16 Oct 2018 at 21:12, Neil Mitchell <<a href="mailto:ndmitchell@gmail.com" target="_blank">ndmitchell@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">> A warning flag is an interesting way to deal with the issue. On the<br>
> other hand, it's not great from an ergonomic perspective; afterall, this<br>
> would mean that all users of HLint (and any other tool requiring special<br>
<br>
Yep, this means every HLint user has to do an extra thing. I (the<br>
HLint author) now have a whole pile of "how do I disable warnings in<br>
Stack", and "what's the equivalent of this in Nix". Personally, it ups<br>
the support level significantly that I wouldn't go this route.<br>
<br>
I think it might be a useful feature in general, as new tools could<br>
use the flag to prototype new types of warning, but I imagine once a<br>
feature gets popular it becomes too much fuss.<br>
<br>
> > I think it makes a lot of sense to have a standard way for third-parties<br>
> > to attach string-y information to Haskell source constructs. While it's<br>
> > not strictly speaking necessary to standardize the syntax, doing<br>
> > so minimizes the chance that tools overlap and hopefully reduces<br>
> > the language ecosystem learning curve.<br>
><br>
> This sounds exactly like the existing ANN pragma, which is what I've wanted LiquidHaskell to move towards for a long time. What is wrong with using the ANN pragma?<br>
<br>
Significant compilation performance penalty and extra recompilation.<br>
ANN pragmas is what HLint currently uses.<br>
<br>
> I'm a bit skeptical of this idea. Afterall, adding cases to the<br>
> lexer for every tool that wants a pragma seems quite unsustainable.<br>
<br>
I don't find this argument that convincing. Given the list already<br>
includes CATCH and DERIVE, the bar can't have been _that_ high to<br>
entry. And yet, the list remains pretty short. My guess is the demand<br>
is pretty low - we're just whitelisting a handful of additional words<br>
that aren't misspellings.<br>
<br>
Thanks, Neil<br>
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<p class="MsoNormal">_______________________________________________<br>
ghc-devs mailing list<br>
<a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a><br>
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<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal">brandon s allbery kf8nh<o:p></o:p></p>
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<p class="MsoNormal"><a href="mailto:allbery.b@gmail.com" target="_blank">allbery.b@gmail.com</a><o:p></o:p></p>
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