GHC 9.2.1-alpha2 now available

Ben Gamari - 2021-04-22

The GHC developers are very happy to announce the availability of the second alpha release in the 9.2.1 series. Binary distributions, source distributions, and documentation are available from

GHC 9.2 will bring a number of exciting features including:

  • Many changes in the area of records, including the new RecordDotSyntax and NoFieldSelectors language extensions, as well as Support for DuplicateRecordFields with PatternSynonyms.

  • Introduction of the new GHC2021 language extension set, giving users convenient access to a larger set of language extensions which have been long considered stable.

  • Merge of ghc-exactprint into the GHC tree, providing infrastructure for source-to-source program rewriting out-of-the-box.

  • Introduction of a BoxedRep RuntimeRep, allowing for polymorphism over levity of boxed objects (#17526)

  • Implementation of the UnliftedDataTypes extension, allowing users to define types which do not admit lazy evaluation

  • The new -hi profiling mechanism which provides significantly improved insight into thunk leaks.

  • Support for the ghc-debug out-of-process heap inspection library

  • Support for profiling of pinned objects with the cost-centre profiler (#7275)

  • Introduction of Haddock documentation support in TemplateHaskell (#5467)

  • Proper support for impredicative types in the form of Quick-Look impredicativity.

  • A native code generator backend for AArch64.

This pre-release brings nearly 50 fixes relative to the first alpha, although the long-awaited ARM NCG backend hasn’t quite landed yet.

As always, do give this a try and open a ticket if you see anything amiss.

Happy testing!