Changelog for ghc-th-abstraction-doc-0.6.0.0-dlh.67.7.noarch.rpm :

* Sun Mar 17 2024 Peter Simons - Update th-abstraction to version 0.6.0.0 revision 2. Upstream has revised the Cabal build instructions on Hackage.
* Sat Sep 30 2023 Peter Simons - Update th-abstraction to version 0.6.0.0 revision 1. [#]# 0.6.0.0 -- 2023.07.31
* Support building with `template-haskell-2.21.0.0` (GHC 9.8).
* Adapt to `TyVarBndr`s for type-level declarations changing their type from `TyVarBndr ()` to `TyVarBndr BndrVis` in `template-haskell`:
* `Language.Haskell.TH.Datatype.TyVarBndr` now backports `type BndrVis = ()`, as well as `BndrReq` and `BndrInvis` pattern synonyms. These make it possible to write code involving `BndrVis` that is somewhat backwards compatible (but do see the caveats in the Haddocks for `BndrInvis`).
* `Language.Haskell.TH.Datatype.TyVarBndr` also backports the following definitions:
* The `type TyVarBndrVis = TyVarBndr BndrVis` type synonym.
* The `DefaultBndrFlag` class, which can be used to write code that is polymorphic over `TyVarBndr` flags while still allowing the code to return a reasonable default value for the flag.
* The `bndrReq` and `bndrInvis` definitions, which behave identically to `BndrReq` and `BndrInvis`.
* `Language.Haskell.TH.Datatype.TyVarBndr` now defines the following utility functions, which are not present in `template-haskell`:
* `plainTVReq`, `plainTVInvis`, `kindedTVReq`, and `kindedTVInvis` functions, which construct `PlainTV`s and `KindedTV`s with particular `BndrVis` flags.
* An `elimTVFlag`, which behaves like `elimTV`, but where the continuation arguments also take a `flag` argument. (Note that the type of this function is slightly different on old versions of `template-haskell`. See the Haddocks for more.)
* A `tvFlag` function, which extracts the `flag` from a `TyVarBndr`. (Note that the type of this function is slightly different on old versions of `template-haskell`. See the Haddocks for more.)
* The types of the `dataDCompat` and `newtypeDCompat` functions have had their `[TyVarBndrUnit]` arguments changed to `[TyVarBndrVis]`, matching similar changes to `DataD` and `NewtypeD` in `template-haskell`. Because `BndrVis` is a synonym for `()` on pre-9.8 versions of GHC, this change is unlikely to break any existing code, provided that you build it with GHC 9.6 or earlier. If you build with GHC 9.8 or later, on the other hand, it is likely that you will need to update your existing code. Here are some possible ways that your code might fail to compile with GHC 9.8, along with some migration strategies:
* Your code passes a `TyVarBndrUnit` in a place where a `TyVarBndrVis` is now expected in GHC 9.8, such as in the arguments to `dataDCompat`: ```hs import \"template-haskell\" Language.Haskell.TH import \"th-abstraction\" Language.Haskell.TH.Datatype (dataDCompat) dec :: DecQ dec = dataDCompat (pure []) d [PlainTV a ()] [] [] where d = mkName \"d\" a = mkName \"a\" ``` With GHC 9.8, this will fail to compile with: ``` error: [GHC-83865] • Couldn\'t match expected type ‘BndrVis’ with actual type ‘()’ • In the second argument of ‘PlainTV’, namely ‘()’ In the expression: PlainTV a () In the third argument of ‘dataDCompat’, namely ‘[PlainTV a ()]’ | | dec = dataDCompat (pure []) d [PlainTV a ()] [] [] | ^^ ``` Some possible ways to migrate this code include:
* Use the `bndrReq` function or `BndrReq` pattern synonym in place of `()`, making sure to import them from `Language.Haskell.TH.Datatype.TyVarBndr`: ```hs ... import \"th-abstraction\" Language.Haskell.TH.Datatype.TyVarBndr dec :: DecQ dec = dataDCompat (pure []) d [PlainTV a bndrReq] [] [] - - Or, alternatively: {- dec = dataDCompat (pure []) d [PlainTV a BndrReq] [] [] - } where ... ```
* Use the `plainTV` function from `Language.Haskell.TH.Datatype.TyVarBndr`, which is now sufficiently polymorphic to work as both a `TyVarBndrUnit` and a `TyVarBndrVis`: ```hs ... import Language.Haskell.TH.Datatype.TyVarBndr dec :: DecQ dec = dataDCompat (pure []) d [plainTV a] [] [] where ... ```
* You may have to replace some uses of `TyVarBndrUnit` with `TyVarBndrVis` in your code. For instance, this will no longer typecheck in GHC 9.8 for similar reasons to the previous example: ```hs import \"template-haskell\" Language.Haskell.TH import \"th-abstraction\" Language.Haskell.TH.Datatype (dataDCompat) dec :: DecQ dec = dataDCompat (pure []) d tvbs [] [] where tvbs :: [TyVarBndrUnit] tvbs = [plainTV a] d = mkName \"d\" a = mkName \"a\" ``` Here is a version that will typecheck with GHC 9.8 and earlier: ```hs ... import \"th-abstraction\" Language.Haskell.TH.Datatype.TyVarBndr dec :: DecQ dec = dataDCompat (pure []) d tvbs [] [] where tvbs :: [TyVarBndrVis] tvbs = [plainTV a] ... ```
* In some cases, the `TyVarBndrUnit`s might come from another place in the code, e.g., ```hs import \"template-haskell\" Language.Haskell.TH import \"th-abstraction\" Language.Haskell.TH.Datatype (dataDCompat) dec :: [TyVarBndrUnit] -> DecQ dec tvbs = dataDCompat (pure []) d tvbs [] [] where d = mkName \"d\" ``` If it is not straightforward to change `dec`\'s type to accept `[TyVarBndrVis]` as an argument, another viable option is to use the `changeTVFlags` function: ```hs ... import \"th-abstraction\" Language.Haskell.TH.Datatype.TyVarBndr dec :: [TyVarBndrUnit] -> DecQ dec tvbs = dataDCompat (pure []) d tvbs\' [] [] where tvbs\' :: [TyVarBndrVis] tvbs\' = changeTVFlags bndrReq tvbs ... ``` This guide, while not comprehensive, should cover most of the common cases one will encounter when migrating their `th-abstraction` code to support GHC 9.8.
* Tue Jun 27 2023 Peter Simons - Update th-abstraction to version 0.5.0.0. [#]# 0.5.0.0 -- 2023.02.27
* Support the `TypeData` language extension added in GHC 9.6. The `DatatypeVariant` data type now has a separate `TypeData` constructor to represent `type data` declarations.
* Add a `Lift` instance for `th-abstraction`\'s compatibility shim for `Specificity` when building with pre-9.0 versions of GHC.
* Thu Mar 30 2023 Peter Simons - Updated spec file to conform with ghc-rpm-macros-2.5.2.
* Mon Feb 27 2023 Peter Simons - Update th-abstraction to version 0.4.5.0 revision 1. Upstream has revised the Cabal build instructions on Hackage.
* Mon Sep 12 2022 Peter Simons - Update th-abstraction to version 0.4.5.0. [#]# 0.4.5.0 -- 2022.09.12
* Fix a bug in which data family declarations with interesting return kinds (e.g., `data family F :: Type -> Type`) would be reified incorrectly when using `reifyDatatype`.
* Sat Jul 23 2022 Peter Simons - Update th-abstraction to version 0.4.4.0. [#]# 0.4.4.0 -- 2022.07.23
* Support free variable substitution and infix resolution for `PromotedInfixT` and `PromotedUInfixT` on `template-haskell-2.19.0.0` or later.
* Thu Sep 02 2021 psimonsAATTsuse.com- Update th-abstraction to version 0.4.3.0. [#]# 0.4.3.0 -- 2021.08.30
* Make `applySubstitution` avoid capturing type variable binders when substituting into `forall`s.
* Fix a bug in which `resolveTypeSynonyms` would incorrectly expand type synonyms that are not applied to enough arguments.
* Allow the test suite to build with GHC 9.2.
* Fri Apr 30 2021 psimonsAATTsuse.com- Update th-abstraction to version 0.4.2.0 revision 1. Upstream has revised the Cabal build instructions on Hackage.
* Wed Dec 30 2020 psimonsAATTsuse.com- Update th-abstraction to version 0.4.2.0. [#]# 0.4.2.0 -- 2020-12-30
* Explicitly mark modules as Safe (or Trustworthy for GHC versions prior to 8.4).