Version 12 (modified by bgamari, 2 years ago) (diff)


GHC plans for 8.4.1

This page is our road-map for what will be in 8.4.

If you believe your favourite 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!


Release in February 2018. Cut release branch in November 2017.

Libraries Status

See Libraries and Migration/8.4.

Release highlights (planned)

Below are the major highlights of 8.4.

  • Further work on compiler performance
  • Improved support for cross-compilation (Moritz Angermann)
  • A more expressive Haskell AST based on Trees That Grow (Shayan Najd)

Build system and miscellaneous changes

  • Improved Windows support, including support for split sections and long file paths (Tamar Christina)
  • Support for building stating libraries for elf and mach-o (-staticlib)

Landed in master branch

Library changes

Build system and miscellaneous changes

  • iserv can be used over the network via iserv-proxy
  • llvm backend uses LLVM5
  • New Shake-based build system, hadrian, will be merged. (Andrey Mokhov)
  • Remove dependency on Hoopl package. (Michal Terepeta, Phab:D3616)

Tickets marked merge with no milestone

Ticket Type Summary Priority Owner
No tickets found

Tickets slated for 8.4.1



Status: new (13 matches)

Ticket Type Summary Priority Owner
#11196 bug TypeInType performance regressions high
#11198 bug TypeInType error message regressions high
#11371 bug Bogus in-scope set in substitutions high niteria
#11523 bug Infinite Loop when mixing UndecidableSuperClasses and the class/instance constraint synonym trick. high simonpj
#12088 bug Type/data family instances in kind checking high
#12506 bug Compile time regression in GHC 8. high bgamari
#12564 bug Type family in type pattern kind high goldfire
#13993 bug Certain inter-module specializations run out of simplifier ticks high
#14253 bug Pattern match checker mistakenly concludes pattern match on pattern synonym is unreachable high
#14297 bug make bindist packages the wrong binaries for cross compilers high angerman
#14495 feature request Relocatable GHC normal angerman
#14856 bug GHC API: Linker failure on loading target multiple times normal
#14858 bug Typed hole subtitution search fails in the REPL normal


Ticket Type Summary Priority Owner
No tickets found