GHC plans for 9.0.1

This page is our road-map for what will be in GHC %9.0.1.

If you believe your favorite thing belongs in this list, but isn't there, please yell. If it's not in the road map, it probably won't get done. Without a lot of support, many things in the road map won't get done either, so we need your help!

Dates

• 16 June 2020: Beginning of feature freeze
• Late June 2020: Cut branch
• Mid september 2020: Alpha releases
• ~24 September 2020: Beta release
• Week of 5th October 2020: Final release candidate

Migration details

See Migration/9.0.

Release highlights (planned)

Below are the major highlights of the 9.0 series.

Compiler

• Linear Types (@aspiwack, !852 (closed), #15981 (closed))
• QualifiedDo (@matt, Proposal #216)
• Signalling NaNs (@carter, #16519)
• NCG register allocation improvements (@AndreasK)
• Various documentation improvements (@Kleidukos)
• Simplified subsumption (@simonpj)
• Explicit specificity in type variable binders (@Gertjan423, #16393 (closed))
• keepAlive# (#17760 (closed), @bgamari)
• Improvements in code generation for runRW# (#15127 (closed), @bgamari)
• Refactoring of GHC module hierarchy (#13009 (closed), @hsyl20)
• New Darwin packaging (#17418, #17854, @trac-conradwt)
• New Windows packaging? (#18104)
• WinIO IO manager for Windows (@Phyx, @AndreasK)
• Reduce FastString memory consumption (!1675 (closed), @dxld)
• Improved GC behavior due to ModIface in compact region (@mpickering)
• Make Q (TExp a) a newtype (@mpickering, !3358 (closed), Proposal 195)
• AArch64 linker fixes (@angerman)
• unified ghc-bignum package (!2231 (closed), @hsyl20)

Runtime system

• Further improvements to the low-latency garbage collector (@bgamari)
• Implement interfaces needed by ghc-debug (!1435 (closed))

Build system and miscellaneous changes

• The Hadrian build system will hopefully become the default (%Make removal)
• The GHCi prompt does not display the loaded modules by default anymore (#18702 (closed))
• Data.Foldable methods maximum{,By}, minimum{,By}, product and sum are now strict by default, as well as the methods used in the List instance (#17867, !4675 (closed))

Tickets

See the %9.0.1 milestone.

See also GHC 9.0 tracking ticket.