Changes between Version 1 and Version 2 of Status/GHC-8.0.2


Ignore:
Timestamp:
May 5, 2016 7:30:31 AM (4 years ago)
Author:
bgamari
Comment:

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  • Status/GHC-8.0.2

    v1 v2  
    2525Below are the major highlights of 8.0.2.
    2626
    27   - TODO
    2827
    29 === In-flight, and likely to land in time
     28  - '''Indexed `Typeable` representations''' [wiki:Typeable/BenGamari] (Ben Gamari, Simon Peyton Jones, et al). While GHC has long supported runtime type reflection through the `Typeable` typeclass, its current incarnation requires care to use, providing little in the way of type-safety. For this reason the implementation of types like `Data.Dynamic` must be implemented in terms of `unsafeCoerce` with no compiler verification.
    3029
    31   - Documentation for `-XTypeInType` (Richard)
     30  GHC 8.2 will address this by introducing indexed type representations, leveraging the type-checker to verify programs using type reflection. This allows facilities like `Data.Dynamic` to be implemented in a fully type-safe manner. See the [[http://research.microsoft.com/en-us/um/people/simonpj/papers/haskell-dynamic/|paper]] for an description of the proposal and the [[https://ghc.haskell.org/trac/ghc/wiki/Typeable/BenGamari|Wiki]] for the current status of the implementation.
     31
     32  - Backpack is targeting to be merged in GHC 8.2. More to come here. (Edward Z Yang)
     33  - Merge `Bifoldable` and `Bitraversable` into `base` (Edward Kmett, Ryan Scott)
     34  - Generalize the `deriving` algorithms for `Eq`, `Functor`, etc. to be able to derive the data types in `Data.Functor.Classes` (`Eq1`, `Eq2`, etc.), `Bifunctor`, `Bifoldable`, and `Bitraversable` (Ryan Scott)
     35  - Deriving strategies (Ryan Scott): grant users the ability to choose explicitly how a class should be `derived` (using a built-in algorithm, `GeneralizedNewtypeDeriving`, `DeriveAnyClass`, or otherwise), addressing #10598.
     36  - Exhaustiveness checking for `EmptyCase`s (Phab:D2105), addressing #10746.
     37
     38=== Back-end and runtime system ===
     39
     40  - Compact regions (Giovanni Campagna, Edward Yang, Phab:D1264, [[http://ezyang.com/papers/ezyang15-cnf.pdf|paper]]). This runtime system feature allows a referentially "closed" set of heap objects to be collected into a "compact region", allowing cheaper garbage collection, heap-object sharing between processes, and the possibility of inexpensive serialization.
     41
     42  - Refactoring and improvements to the cost-center profiler (Ben Gamari, Phab:D1722): Allow heap profiler samples to be directed to the GHC eventlog, allowing correlation with other program events, enabling easier analysis by tooling and eventual removal of the old, rather crufty `.hp` profile format.
     43
     44  - Further improvements to debugging information (Ben Gamari): There are still a number of outstanding issues with GHC's DWARF implementation, some of which even carry the potential to crash the runtime system during stacktrace collection. GHC 8.2 will hopefully have these issues resolved, allowing debugging information to be used by end-user code in production.
     45
     46  With stable stack unwinding support comes a number of opportunities for new serial and parallel performance analysis tools (e.g. statistical profiling) and debugging. As GHC's debugging information improves, we expect to see tooling developed to support these applications. See the [[https://ghc.haskell.org/trac/ghc/wiki/DWARF/80Status|DWARF status page]] for futher information.
     47
     48   - Support for NUMA systems (Simon Marlow, [[https://github.com/simonmar/ghc/tree/numa|in-progress]]).  The aim is to reduce the number of remote memory accesses for multi-socket systems that have a mixture of local and remote memory.
     49
     50   - Experimental changes to the scheduler (Simon Marlow, [[https://github.com/simonmar/ghc/commit/7e05ec18b4eda8d97e37015d415e627353de6b50|in progress]]) that enable the number of threads used for GC to be lower than the `-N` setting.
     51
     52=== Frontend, build system and miscellaneous changes ===
     53
     54  - New Shake-based build system, `hadrian`, will be merged.  (Andrey Mokhov)
     55  - The [[ImprovedLLVMBackend|improved LLVM backend plan]] plan didn't make the cut for 8.0, but will for 8.2 (Austin Seipp)
     56  - Deterministic builds [wiki:DeterministicBuilds]. Given the same environment, file and flags produce ABI compatible binaries. (Bartosz Nitka, in-progress)
    3257
    3358
    34 === Landed in `ghc-8.0`
     59=== Landed in `ghc-8.0` branch
    3560
    3661  - TODO
    37 
    38 == Known issues with release candidate 1 ==
    39 
    40 None yet.
    4162
    4263== Tickets marked merge with no milestone