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Make type families in Data.Row.Internal polykinded #20
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LGTM, @dwincort what say you? |
dwincort
approved these changes
Apr 25, 2018
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#19
The primary motivation is to be able to use
.==and.+to construct rows of kinds other than*.Examples.lhscompiles without any changes, however this change is potentially breaking becauseForallis now poly-kinded and thus previously working programs may require additional annotations to compile.The changes to the
Forallclass seem to be the sole reason whyData.Row.RecordandData.Row.Variantsneeded to be touched. At a high level it makes sense to me to make said class poly-kinded since we could have something likenewtype RecF (r :: Row (* -> *)) (a :: *),newtype VarF (r :: Row (* -> *)) (a :: *)for which we would be able to write instancesForall f Functor => Functor (RecF r),Forall f Functor => Functor (VarF r).I don't totally understand the type signatures though, so if I messed up anywhere it's probably there.