2.1. Version 9.16.1¶
The significant changes to the various parts of the compiler are listed in the following sections. See the migration guide on the GHC Wiki for specific guidance on migrating programs to this release.
2.1.1. Language¶
2.1.2. Compiler¶
Code coverage’s (
-fhpc) treatment of record fields now extends beyond record fields accessed viaRecordWildCardsandNamedFieldPuns, and also handles access to nested record fields. That is, in a pattern such asFoo{bar = Bar{baz = b}}bothbarandbazwill now be marked as covered ifbis evaluated. Note that this currently only works when record fields (or values contained within them) are bound to variables. The very similar patternFoo{bar = Bar{baz = 42}}will will not yet markbarorbazas covered.
2.1.3. GHCi¶
2.1.4. Runtime system¶
Add a new poll I/O manager, based on the classic unix poll() API. It is available in the single-threaded RTS on posix platforms. The select I/O manager remains the default for this combination for now, but this default may change in future releases. The new I/O manager can be selected via the runtime flag
--io-manager=(name).Compared to the select I/O manager, this one has slightly less severe restrictions on the number of sockets/pipes that can be waited on, though it still scales poorly for waiting on socket/pipe readiness. It does however scale much better for thread timers (such as threadDelay), and improves timer precision on 32bit Linux and 32bit FreeBSD from milliseconds to microseconds.
This I/O manager introduces new infrastructure for I/O managers that is intended to be used in future for a new generation of in-RTS I/O managers, using more scalable platform-specific APIs (such as epoll, io_uring and kqueue). This first one, based on poll(), is merely intended to be portable.
2.1.5. Cmm¶
2.1.6. base library¶
2.1.7. ghc-prim library¶
2.1.8. ghc library¶
2.1.9. ghc-heap library¶
2.1.10. ghc-experimental library¶
2.1.11. template-haskell library¶
We have added the
addDependentDirectoryfunction to matchaddDependentFile, which adds a directory to the list of dependencies that the recompilation checker will look at to determine if a module needs to be recompiled.
2.1.12. Included libraries¶
The package database provided with this distribution also contains a number of packages other than GHC itself. See the changelogs provided with these packages for further change information.
| Package | Version | Reason for inclusion |
|---|---|---|
ghc |
9.15 | The compiler itself |
Cabal-syntax |
3.16.0.0 | Dependency of |
Cabal |
3.16.0.0 | Dependency of |
Win32 |
2.14.2.1 | Dependency of |
array |
0.5.8.0 | Dependency of |
base |
4.22.0.0 | Core library |
binary |
0.8.9.3 | Dependency of |
bytestring |
0.12.2.0 | Dependency of |
containers |
0.8 | Dependency of |
deepseq |
1.5.1.0 | Dependency of |
directory |
1.3.10.0 | Dependency of |
exceptions |
0.10.9 | Dependency of |
file-io |
0.1.5 | Dependency of |
filepath |
1.5.4.0 | Dependency of |
ghc-boot-th |
9.15 | Internal compiler library |
ghc-boot |
9.15 | Internal compiler library |
ghc-compact |
0.1.0.0 | Core library |
ghc-heap |
9.15 | GHC heap-walking library |
ghc-prim |
0.13.1 | Core library |
ghci |
9.15 | The REPL interface |
haskeline |
0.8.3.0 | Dependency of |
hpc |
0.7.0.2 | Dependency of |
integer-gmp |
1.1 | Core library |
mtl |
2.3.1 | Dependency of |
os-string |
2.0.7 | Dependency of |
parsec |
3.1.18.0 | Dependency of |
pretty |
1.1.3.6 | Dependency of |
process |
1.6.26.1 | Dependency of |
stm |
2.5.3.1 | Dependency of |
template-haskell |
2.24.0.0 | Core library |
terminfo |
0.4.1.7 | Dependency of |
text |
2.1.3 | Dependency of |
time |
1.15 | Dependency of |
transformers |
0.6.1.2 | Dependency of |
unix |
2.8.7.0 | Dependency of |
xhtml |
3000.2.2.1 | Dependency of |
haddock-api |
2.30.0 | Dependency of |
haddock-library |
1.11.0 | Dependency of |