Version 0.17.2.0 (2025-09-08)

• Fix the package failing to build on GHC 9.6.1 through 9.6.6 and on GHC 9.8.1 through 9.8.3. GHC versions 9.6.7 and 9.8.4 are unaffected.

Version 0.17.1.0 (2025-08-27)

• Fix a regression, introduced in 0.17.0.0, in which splitTyConApp_upTo would fail to take into account equalities of the form tv1 ~ tv2.

Version 0.17.0.0 (2025-08-25)

• splitTyConApp_upTo now additionally returns a [Coercion] for tracking Given dependencies (which should be passed to functions such as mkPluginUnivCo, mkPluginUnivEvTerm and mkTyFamAppReduction).

Version 0.16.2.0 (2025-08-22)

• splitTyConApp_upTo now correctly splits apart type families. This ensures it is a valid drop-in replacement for splitTyConApp_maybe (fixes issue #13).

Version 0.16.1.0 (2025-07-18)

• Correctness fix for the GHC.TcPlugin.API.TyConSubst module: ensure that the TyConSubst does not mistake representational Given equalities for nominal equalities. For the time being, the splitTyConApp_upTo functionality only works at nominal role.

Version 0.16.0.0 (2025-07-18)

• Re-export tyConDataCons, tyConSingleDataCon_maybe, tyConSingleDataCon, dataConTyCon, isNewTyCon and isNewDataCon from GHC.

• The isWanted function now correctly returns False for derived constraints. This is only relevant for GHC 9.2 and below.

• Add GHC.TcPlugin.API.TyConSubst module, which implements logic for recognising when a type is a TyConApp up to Given constraints.

Version 0.15.0.0 (2025-06-03)

• Remove tcPluginIO in favour of new MonadIO instance.
  To migrate, use liftIO instead of tcPluginIO.

• Add lookupTHName function, which allows looking up Template Haskell names in typechecker plugins. Useful in conjunction with TemplateHaskellQuotes.

• Helper functions to construct evidence terms have been adjusted to return values of type EvExpr, rather than EvTerm. This makes the functions more composable, and allows typechecker plugin to provide evidence for quantified constraints more easily.

  Affected functions: evDFunApp, evDataConApp, evCast.

  To migrate, you will need to manually wrap evidence terms with the EvExpr constructor in places that expect an EvTerm.

• Added natKind, symbolKind and charKind for the kinds of type-level Nat, Symbol and Char.

• Added several re-exports from the ghc library:

  • isGiven & isWanted.
  • ctEvPred, ctEvId, ctEvExpr and ctEvLoc.
  • className & tyConName.
  • isEqPred (unboxed equality) and isEqClassPred (boxed equality).
  • evId & ctEvId.
  • typeKind.
  • nonDetCmpType.

• Removed re-exports of ctev_pred, ctev_loc, ctev_evar, and ctev_dest.

  Migration: use ctEvPred instead of ctev_pred and ctEvLoc instead of ctev_loc. Uses of ctev_evar and ctev_dest should be covered by ctEvEvId and/or ctEvExpr.

Version 0.14.0.0 (2024-11-28)

• Rename mkPrimEqPredRole to mkEqPredRole. This is a re-exported function from GHC, and the renaming adapts to the renaming in GHC-9.13.

Version 0.13.0.0 (2024-10-30)

• Update to changes in the type of GHC’s mkUnivCo in order to (properly) add support for GHC 9.12.

• Change mkPluginUnivCo, mkPluginUnivEvTerm and mkTyFamAppReduction to take a [Coercion] rather than a DVarSet for specifying dependencies.

• Stop re-exporting DVarSet, emptyDVarSet, extendDVarSet, unionDVarSet, unitDVarSet, and mkDVarSet.

• Update documentation to suggest using ctEvCoercion rather than ctEvId to specify coercions that a UnivCo depends on.

• Re-export ctEvCoercion, and stop re-exporting ctEvId.

Version 0.12.0.0 (2024-10-22)

• Add preliminary support for GHC 9.12.

• mkPluginUnivCo, mkPluginUnivEvTerm and mkTyFamAppReduction now all take an additional DVarSet argument which allows specifying evidence that we depend on. This stops evidence terms being floated out past used enclosing Givens (see GHC issue #23923).

• Re-export DVarSet, emptyDVarSet, extendDVarSet, unionDVarSet, unitDVarSet, and mkDVarSet, as well as ctEvId, in order to facilitate construction and manipulation of DVarSets.

• Re-export GHC.Types.Unique.Set, GHC.Types.Unique.DSet.

Version 0.11.0.0 (2023-08-29)

• Add support for GHC 9.8.

• Re-export functionality relating to GHC’s constraint solving TcS monad, such as {get,set}InertSet, {get,set}TcEvBindsMap.

• Re-export readTcRef and writeTcRef.

Version 0.10.0.0 (2023-02-28)

• Introduce resolveImport, and make PkgQual opaque.

• Rename tcRewriterWanteds to tcRewriterNewWanteds (bringing it in line with nomenclature in GHC 9.4).

Version 0.9.0.0 (2023-01-24)

• Add support for GHC 9.6 and transformers 0.6.

• The One and Many pattern synonyms are now OneTy and ManyTy.

• Use mkInvisFunTy/mkInvisFunTys instead of mkInvisFunTyMany/mkInvisFunTysMany.

Version 0.8.3.0 (2022-10-05)

• Bugfix for the GHC 9.0 rewriter plugin compatibility shim: fix coercion orientations in family application cache

Version 0.8.2.0 (2022-10-05)

• Bugfix for the GHC 9.0 rewriter plugin compatibility shim: fix coercion orientations in family rewriting.

Version 0.8.1.0 (2022-10-05)

• Bugfix for the GHC 9.2 rewriter plugin compatibility shim: fix coercion orientations in family rewriting.

Version 0.8.0.0 (2022-07-07)

• Compatibility for GHC 9.4.

• Change API for lookupImportedModule to use PkgQual and UnitId instead of Maybe FastString, with back-compatibility function pkgQual_pkg for use with older module lookup functions.

• Re-export splitAppTys and unpackFS.

Version 0.7.1.0 (2022-01-04)

• newWanted now always uses the CtLoc information that it is provided with, as opposed to obtaining some information from the monadic environment. This means you no longer need to wrap calls to newWanted in setCtLocM to ensure that GHC reports the correct source span when reporting unsolved Wanteds in error messages.

• Remove the newDerived function, as Derived constraints are going to be removed from GHC.

Version 0.7.0.0 (2021-12-31)

• Re-export functions for dealing with type-level literals, such as mkNumLitTy and isStrLitTy.

• Re-export functions for splitting apart type applications, such as splitAppTy_maybe and tyConAppTyCon_maybe.

• Redefine and re-export mkUncheckedIntExpr for GHC versions prior to 9.0.

• Re-export some basic types from GHC.Types.Basic such as Arity, PromotionFlag and Boxity.

• Re-export GHC.Builtin.Names and GHC.Builin.Types.Prim.

• Provide MonadThings instances for TcPluginM monads.

Version 0.6.1.0 (2021-12-13)

• Re-export various useful types and functions to deal with type and coercion variables.

• Re-export a few types and functions to deal with source locations.

• Remove some re-exports for constructing function types, as not all functions make sense across all GHC versions supported by the library.

• Re-export panic and pprPanic.

Version 0.6.0.0 (2021-12-13)

• Add support for GHC 8.8.

• Re-export evDataConApp, which is useful for constructing typeclass dictionaries.

Version 0.5.1.0 (2021-08-31)

• Fix a bug in the type-family rewriting compatibility layer (GHC 8.10, 9.0, 9.2) by correctly downgrading the coercion used to cast the evidence, when necessary.

Version 0.5.0.0 (2021-08-30)

• Re-export some additional types and functions that are useful for inspecting and constructing evidence terms, such as mkTyVar, newName, mkLocalId, lookupEvBind…

Version 0.4.1.0 (2021-08-24)

• Re-export a few GHC modules, such as GHC.Core.Make and GHC.Plugins. These re-exports might be changed to be more selective in the future to aid cross-version compatibility.

Version 0.4.0.0 (2021-08-24)

• Adapt to GHC 9.4 changes in the TcPluginSolveResult datatype: are now able to solve and emit constraints even when reporting a contradiction. This can help with error messages. Unfortunately these extra constraints will be dropped in versions of GHC prior to 9.4.

• Add a utility module for name resolution using constrained traversals.

• Add compatibility for GHC 8.10.

Version 0.3.1.0 (2021-08-09)

Ensure that the coercions stored in Reductions are always oriented left-to-right, by making the internal rewriting compatibility layer also use left-to-right coercions.

Version 0.3.0.0 (2021-08-04)

Account for changes in rewriting in GHC 9.4:

• rewriter plugins can no longer emit new Wanted constraints if they don’t rewrite the type family application;
• coercions in the rewriter are now oriented left-to-right, requiring mkTyFamAppReduction to be adapted.

Version 0.2.0.0 (2021-07-22)

Initial release on Hackage.