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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Jan,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Type checking and desugaring for arrow syntax has received Absolutely No Love for several years. I do not understand how it works very well, and I would not be at all surprised if it is broken
in corner cases.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">It really needs someone to look at it carefully, document it better, and perhaps refactor it – esp by using a different data type rather than piggy-backing on HsExpr.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">In the light of that understanding, I think rebindable syntax will be easier.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">I don’t know if you are up for that, but it’s a rather un-tended part of GHC.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Thanks<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><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>Richard Eisenberg<br>
<b>Sent:</b> 28 November 2016 22:30<br>
<b>To:</b> Jan Bracker <jan.bracker@googlemail.com><br>
<b>Cc:</b> ghc-devs@haskell.org<br>
<b>Subject:</b> Help needed: Restrictions of proc-notation with RebindableSyntax<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">Jan’s question is a good one, but I don’t know enough about procs to be able to answer. I do know that the answer can be found by looking for uses of `tcSyntaxOp` in the TcArrows module.... but I just can’t translate it all to source Haskell,
having roughly 0 understanding of this end of the language.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Can anyone else help Jan here?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Richard<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 Nov 23, 2016, at 4:34 AM, Jan Bracker 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"><o:p> </o:p></p>
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<p class="MsoNormal">Hello,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I want to use the proc-notation together with RebindableSyntax. So far what I am trying to do is working fine, but I would like to know what the exact restrictions on the supplied functions are. I am introducing additional indices and constraints
on the operations. The documentation [1] says the details are in flux and that I should ask directly.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Best,<o:p></o:p></p>
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<p class="MsoNormal">Jan<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">[1] <a href="https://na01.safelinks.protection.outlook.com/?url=https:%2F%2Fdownloads.haskell.org%2F~ghc%2Flatest%2Fdocs%2Fhtml%2Fusers_guide%2Fglasgow_exts.html%23rebindable-syntax-and-the-implicit-prelude-import&data=02%7C01%7Csimonpj%40microsoft.com%7C80e472cedf78463bd18408d417de1af5%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636159690104764444&sdata=ygqePSmgcPKnPmKDBfZplkyjG9BIDBO1L1MWHNpqw88%3D&reserved=0">https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#rebindable-syntax-and-the-implicit-prelude-import</a><o:p></o:p></p>
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<p class="MsoNormal">_______________________________________________<br>
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