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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">we already have such a shared library, I think: bin-package-db.  would that do?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Simon<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> ghc-devs [mailto:ghc-devs-bounces@haskell.org]
<b>On Behalf Of </b>Michael Smith<br>
<b>Sent:</b> 02 September 2015 09:21<br>
<b>To:</b> Matthew Pickering<br>
<b>Cc:</b> GHC developers<br>
<b>Subject:</b> Re: Shared data type for extension flags<o:p></o:p></span></p>
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That sounds like a good approach. Are there other things that would go nicely<br>
in a shared package like this, in addition to the extension data type?<o:p></o:p></p>
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On Wed, Sep 2, 2015 at 1:00 AM, Matthew Pickering <<a href="mailto:matthewtpickering@gmail.com" target="_blank">matthewtpickering@gmail.com</a>> wrote:<o:p></o:p></p>
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Surely the easiest way here (including for other tooling - ie<br>
haskell-src-exts) is to create a package which just provides this<br>
enumeration. GHC, cabal, th, haskell-src-exts and so on then all<br>
depend on this package rather than creating their own enumeration.<o:p></o:p></p>
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<br>
On Wed, Sep 2, 2015 at 9:47 AM, Michael Smith <<a href="mailto:michael@diglumi.com">michael@diglumi.com</a>> wrote:<br>
> #10820 on Trac [1] and D1200 on Phabricator [2] discuss adding the<br>
> capababilty<br>
> to Template Haskell to detect which language extensions enabled.<br>
> Unfortunately,<br>
> since template-haskell can't depend on ghc (as ghc depends on<br>
> template-haskell),<br>
> it can't simply re-export the ExtensionFlag type from DynFlags to the user.<br>
><br>
> There is a second data type encoding the list of possible language<br>
> extensions in<br>
> the Cabal package, in Language.Haskell.Extension [3]. But template-haskell<br>
> doesn't already depend on Cabal, and doing so seems like it would cause<br>
> difficulties, as the two packages can be upgraded separately.<br>
><br>
> So adding this new feature to Template Haskell requires introducing a<br>
> *third*<br>
> data type for language extensions. It also requires enumerating this full<br>
> list<br>
> in two more places, to convert back and forth between the TH Extension data<br>
> type<br>
> and GHC's internal ExtensionFlag data type.<br>
><br>
> Is there another way here? Can there be one single shared data type for this<br>
> somehow?<br>
><br>
> [1] <a href="https://ghc.haskell.org/trac/ghc/ticket/10820" target="_blank">https://ghc.haskell.org/trac/ghc/ticket/10820</a><br>
> [2] <a href="https://phabricator.haskell.org/D1200" target="_blank">https://phabricator.haskell.org/D1200</a><br>
> [3]<br>
> <a href="https://hackage.haskell.org/package/Cabal-1.22.4.0/docs/Language-Haskell-Extension.html" target="_blank">
https://hackage.haskell.org/package/Cabal-1.22.4.0/docs/Language-Haskell-Extension.html</a><br>
><o:p></o:p></p>
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> _______________________________________________<br>
> ghc-devs mailing list<br>
> <a href="mailto:ghc-devs@haskell.org">ghc-devs@haskell.org</a><br>
> <a href="http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs" target="_blank">
http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs</a><br>
><o:p></o:p></p>
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