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<div dir="ltr" data-setdir="false"><div dir="ltr" data-setdir="false"><span style="color: rgb(29, 29, 29); font-family: Helvetica Neue, Helvetica, Arial, sans-serif; background-color: rgb(255, 255, 255);">Thank you to everyone who replied. The thing I was misunderstanding was, to quote Jade, </span><span style="font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">"This attempts to define `Ord a` in general, for *every* type `a` at </span><span style="font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">once. The `Lex2 a` constraint is only checked *after* the compiler has </span><span style="font-family: Helvetica Neue, Helvetica, Arial, sans-serif;">decided this is the instance to use."</span></div><div><span style="color: rgb(29, 29, 29); font-family: Helvetica Neue, Helvetica, Arial, sans-serif; background-color: rgb(255, 255, 255);"><br></span></div><div dir="ltr" data-setdir="false"><span style="color: rgb(29, 29, 29); font-family: Helvetica Neue, Helvetica, Arial, sans-serif; background-color: rgb(255, 255, 255);">I appreciate seeing how a Proxy constructor, or DerivingVia, would solve the problem. However, I decided just to document carefully what I was doing.</span></div><br></div><div><br></div>
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On Wednesday, March 26, 2025 at 06:14:00 PM EDT, Jade Hagborg <jhagborg@quasicoherent.solutions> wrote:
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<div><div dir="ltr">On Wed, 2025-03-26 at 18:08 -0400, Jade Hagborg via Haskell-Cafe wrote:<div class="ydp5e3a44b0yqt2880866758" id="ydp5e3a44b0yqtfd62517"><br clear="none">> instance (Primary a, Secondary a) => Ord (Lex2 a) where<br clear="none">> compare (MkLex2 x) (MkLex2 y) = comp1 x y <> comp2 x y</div><br clear="none"><br clear="none">My bad (copy-paste error), should be<br clear="none"><br clear="none"> instance (Primary a, Secondary a) => Ord (UsePrimaryAndSecondary a) where<br clear="none"> compare (MkUsePrimaryAndSecondary x) <br clear="none"> (MkUsePrimaryAndSecondary y) = comp1 x y <> comp2 x y<br clear="none"><br clear="none">Sorry if that caused confusion.<div class="ydp5e3a44b0yqt2880866758" id="ydp5e3a44b0yqtfd66573"><br clear="none"><br clear="none"></div></div></div>
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