template-haskell 2.17

[locallycompact]

The new template haskell in ghc 9 offered these migration instructions for TyVarBndr

https://gitlab.haskell.org/ghc/ghc/-/wikis/migration/9.0#template-haskell-217

I've naively attempted to resolve this by setting TyVarBndrSpec here

locallycompact@73cbba0

But I get one type error.

composite-base                > /home/lc/Source/github.com/composite/composite-base/src/Composite/TH.hs:163:59: error:
composite-base                >     • Couldn't match type ‘()’ with ‘Specificity’
composite-base                >       Expected: Control.Lens.Getter.Getting
composite-base                >                   (base-4.15.0.0:Data.Semigroup.Internal.Endo
composite-base                >                      [(Name, [TyVarBndrSpec], Type)])
composite-base                >                   [Dec]
composite-base                >                   (Name, [TyVarBndrSpec], Type)
composite-base                >         Actual: ((Name, [Language.Haskell.TH.Lib.Internal.TyVarBndrUnit],
composite-base                >                   Type)
composite-base                >                  -> Data.Functor.Const.Const
composite-base                >                       (base-4.15.0.0:Data.Semigroup.Internal.Endo
composite-base                >                          [(Name, [TyVarBndrSpec], Type)])
composite-base                >                       (Name, [Language.Haskell.TH.Lib.Internal.TyVarBndrUnit], Type))
composite-base                >                 -> [Dec]
composite-base                >                 -> Data.Functor.Const.Const
composite-base                >                      (base-4.15.0.0:Data.Semigroup.Internal.Endo
composite-base                >                         [(Name, [TyVarBndrSpec], Type)])
composite-base                >                      [Dec]
composite-base                >     • In the first argument of ‘toListOf’, namely ‘(each . _TySynD)’
composite-base                >       In the second argument of ‘(.)’, namely ‘toListOf (each . _TySynD)’
composite-base                >       In the second argument of ‘(.)’, namely
composite-base                >         ‘map fieldDecMay . toListOf (each . _TySynD)’
composite-base                >     |
composite-base                > 163 |   let fieldDecs = catMaybes . map fieldDecMay . toListOf (each . _TySynD) $ decs

I can't really see what's going on here, but _TySynD doesn't look like something I want to change, but if I change these all to TyVarBndrUnit, then I get an error trying to use ForallT, which also doesn't look like like something I want to change.

composite-base                > /home/lc/Source/github.com/composite/composite-base/src/Composite/TH.hs:220:30: error:
composite-base                >     • Couldn't match type ‘()’ with ‘Specificity’
composite-base                >       Expected: [TyVarBndr Specificity]
composite-base                >         Actual: [TyVarBndr ()]
composite-base                >     • In the first argument of ‘ForallT’, namely ‘lensBinders’
composite-base                >       In the second argument of ‘SigD’, namely
composite-base                >         ‘(ForallT lensBinders lensContext lensType)’
composite-base                >       In the expression:
composite-base                >         SigD lensName (ForallT lensBinders lensContext lensType)
composite-base                >     |
composite-base                > 220 |     , SigD lensName (ForallT lensBinders lensContext lensType)
composite-base                >     |                              ^^^^^^^^^^^
composite-base                >
composite-base                > /home/lc/Source/github.com/composite/composite-base/src/Composite/TH.hs:240:31: error:
composite-base                >     • Couldn't match type ‘()’ with ‘Specificity’
composite-base                >       Expected: [TyVarBndr Specificity]
composite-base                >         Actual: [TyVarBndr ()]
composite-base                >     • In the first argument of ‘ForallT’, namely ‘prismBinders’
composite-base                >       In the second argument of ‘SigD’, namely
composite-base                >         ‘(ForallT prismBinders prismContext prismType)’
composite-base                >       In the expression:
composite-base                >         SigD prismName (ForallT prismBinders prismContext prismType)
composite-base                >     |
composite-base                > 240 |     , SigD prismName (ForallT prismBinders prismContext prismType)

[locallycompact]

I went the long way round, I tried th-abstractions but it didn't seem to make sense since we were using a type synonym binding, and that couldn't be then made to be polymorphic. This at least type checks but I haven't tested the new version.

#49