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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Friends<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">I propose that we support the GHC proposal “<a href="https://github.com/ghc-proposals/ghc-proposals/blob/rae/constraint-vs-type/proposals/0000-constraint-vs-type.rst">Declare Constraint is
not apart from Type</a>”<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Currently GHC operates an uneasy compromise:<o:p></o:p></span></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level1 lfo1"><span style="font-family:"Calibri",sans-serif">Constraint and Type are treated as distinct in the type checker (e.g. do not unify)<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l1 level1 lfo1"><span style="font-family:"Calibri",sans-serif">But they are treated as the same in Core<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">I have spent ages in discussion with Richard and others for how to fix this wart. Really, they should be either<o:p></o:p></span></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span style="font-family:"Calibri",sans-serif">completely different (like Int and Bool), or
<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span style="font-family:"Calibri",sans-serif">completely the same (like [Char] and String).<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">But both these stances have problems, and nothing satisfying has emerged. So this proposal simply fixes the worst aspect (unsoundness) of the current setup.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">So I regard it as a way to stay explicitly non-committal, leaving the main question open.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">There are a couple of clarifications I’d like which I’ve put on the discussion thread.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Simon<o:p></o:p></span></p>
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