I'm afraid I don't know a quick answer to that one. Does anyone else? If no one answers, write back in a few days and I'll look into it.
Richard > On May 1, 2018, at 3:09 AM, alice <alicekoroleva...@gmail.com> wrote: > > Thanks a lot, this helped! > > But sorry for asking, before this problem I evaluated Cmp on some values with > * kinds, and I used (mkTemplateAnonTyConBinders [ liftedTypeKind, > liftedTypeKind ]) to make the input kinds for TyCon. > Changing function to mkTemplateTyConBinders (right now this part looks like > 'binders = mkTemplateTyConBinders [ liftedTypeKind, liftedTypeKind ] (\ks -> > ks)') made my type family not evaluating: > > :kind! Cmp 4 5 > Cmp 4 5 :: Ordering > = Cmp 4 5 > > And before that change: > > :kind! Cmp (Proxy 5) (Proxy 4) > Cmp (Proxy 5) (Proxy 4) :: Ordering > = 'GT > > I can see from debug output that before that change functions in > BuiltInSynFamily like matchFamCmpType (has the same meaning as > matchFamCmpNat) had been applied to values, but now they aren’t. What am I > missing? > >> 30 апр. 2018 г., в 17:38, Richard Eisenberg <r...@cs.brynmawr.edu >> <mailto:r...@cs.brynmawr.edu>> написал(а): >> >> Hi Alice, >> >> You'll need mkTemplateTyConBinders, not the two variants of that function >> you use below. The problem is that both mkTemplateKindTyConBinders and >> mkTemplateAnonTyConBinders pull Uniques starting from the same value, and so >> GHC gets very confused when multiple arguments to your TyCon have the same >> Uniques. mkTemplateTyConBinders, on the other hand, allows you to specify >> dependency among your arguments without confusing Uniques. You can see a >> usage of this function in TysPrim.proxyPrimTyCon. >> >> I hope this helps! >> Richard >> >> PS: I've made this mistake myself several times, and it's quite baffling to >> debug! >> >>> On Apr 30, 2018, at 8:27 AM, alice <alicekoroleva...@gmail.com >>> <mailto:alicekoroleva...@gmail.com>> wrote: >>> >>> Hello. I’m trying to make a type family with resolving it inside type >>> checking classes, like CmpNat. Its type signature is «type family Cmp (a :: >>> k1) (b :: k2) :: Ordering», so the function is poly kinded. But it seems >>> unclear how to make its TyCon. I’ve tried to follow the CmpNat and >>> CmpSymbol style, and also saw Any TyCon in TysWiredIn. So this is my >>> attempt: >>> >>> typeCmpTyCon :: TyCon >>> typeCmpTyCon = >>> mkFamilyTyCon name >>> (binders ++ (mkTemplateAnonTyConBinders [ input_kind1, input_kind2 ])) >>> orderingKind >>> Nothing >>> (BuiltInSynFamTyCon ops) >>> Nothing >>> NotInjective >>> where >>> name = mkWiredInTyConName UserSyntax gHC_TYPELITS (fsLit "Cmp") >>> typeCmpTyFamNameKey typeCmpTyCon >>> ops = BuiltInSynFamily >>> { sfMatchFam = matchFamCmpType >>> , sfInteractTop = interactTopCmpType >>> , sfInteractInert = \_ _ _ _ -> [] >>> } >>> binders@[kv1, kv2] = mkTemplateKindTyConBinders [ liftedTypeKind, >>> liftedTypeKind ] >>> input_kind1 = mkTyVarTy (binderVar kv1) >>> input_kind2 = mkTyVarTy (binderVar kv2) >>> >>> ghci says this: >>> >>> :kind Cmp >>> Cmp :: forall {k0} {k1}. k0 -> k1 -> Ordering >>> >>> But then I try to apply it to some values and get this exception: >>> >>> :kind! Cmp 4 5 >>> >>> <interactive>:1:15: error: >>> • Expected kind ‘k0’, but ‘4’ has kind ‘Nat’ >>> • In the first argument of ‘Cmp’, namely ‘4’ >>> In the type ‘Cmp 4 5’ >>> >>> <interactive>:1:17: error: >>> • Expected kind ‘k1’, but ‘5’ has kind ‘Nat’ >>> • In the second argument of ‘Cmp’, namely ‘5’ >>> In the type ‘Cmp 4 5’ >>> >>> Does anyone know where I made a mistake? Any help would be appreciated. >>> _______________________________________________ >>> ghc-devs mailing list >>> ghc-devs@haskell.org <mailto:ghc-devs@haskell.org> >>> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >>> <http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs> >> >
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