# Changelog for [`base` package](http://hackage.haskell.org/package/base)
## 4.16.1.0 *Feb 2022*
* Shipped with GHC 9.2.2
* The following Foreign C types now have an instance of `Ix`:
CChar, CSChar, CUChar, CShort, CUShort, CInt, CUInt, CLong, CULong,
CPtrdiff, CSize, CWchar, CSigAtomic, CLLong, CULLong, CBool, CIntPtr, CUIntPtr,
CIntMax, CUIntMax.
## 4.16.0.0 *Nov 2021*
* Shipped with GHC 9.2.1
* The unary tuple type, `Solo`, is now exported by `Data.Tuple`.
* Add a `Typeable` constraint to `fromStaticPtr` in the class `GHC.StaticPtr.IsStatic`.
* Make it possible to promote `Natural`s and remove the separate `Nat` kind.
For backwards compatibility, `Nat` is now a type synonym for `Natural`.
As a consequence, one must enable `TypeSynonymInstances`
in order to define instances for `Nat`. Also, different instances for `Nat` and `Natural`
won't typecheck anymore.
* Add `Data.Type.Ord` as a module for type-level comparison operations. The
`(<=?)` type operator from `GHC.TypeNats`, previously kind-specific to
`Nat`, is now kind-polymorphic and governed by the `Compare` type family in
`Data.Type.Ord`. Note that this means GHC will no longer deduce `0 <= n`
for all `n` any more.
* Add `cmpNat`, `cmpSymbol`, and `cmpChar` to `GHC.TypeNats` and `GHC.TypeLits`.
* Add `CmpChar`, `ConsSymbol`, `UnconsSymbol`, `CharToNat`, and `NatToChar`
type families to `GHC.TypeLits`.
* Add the `KnownChar` class, `charVal` and `charVal'` to `GHC.TypeLits`.
* Add `Semigroup` and `Monoid` instances for `Data.Functor.Product` and
`Data.Functor.Compose`.
* Add `Functor`, `Applicative`, `Monad`, `MonadFix`, `Foldable`, `Traversable`,
`Eq`, `Ord`, `Show`, `Read`, `Eq1`, `Ord1`, `Show1`, `Read1`, `Generic`,
`Generic1`, and `Data` instances for `GHC.Tuple.Solo`.
* Add `Eq1`, `Read1` and `Show1` instances for `Complex`;
add `Eq1/2`, `Ord1/2`, `Show1/2` and `Read1/2` instances for 3 and 4-tuples.
* Remove `Data.Semigroup.Option` and the accompanying `option` function.
* Make `allocaBytesAligned` and `alloca` throw an IOError when the
alignment is not a power-of-two. The underlying primop
`newAlignedPinnedByteArray#` actually always assumed this but we didn't
document this fact in the user facing API until now.
`Generic1`, and `Data` instances for `GHC.Tuple.Solo`.
* Under POSIX, `System.IO.openFile` will no longer leak a file descriptor if it
is interrupted by an asynchronous exception (#19114, #19115).
* Additionally export `asum` from `Control.Applicative`
* `fromInteger :: Integer -> Float/Double` now consistently round to the
nearest value, with ties to even.
* The `Data.Int.Int{8,16,32}` (resp. `Data.Word.Word{8,16,32}`) types are now
represented by their associated fixed-width unlifted types rather than
`Int#` (resp. `Word#`).
* Additions to `Data.Bits`:
- Newtypes `And`, `Ior`, `Xor` and `Iff` which wrap their argument,
and whose `Semigroup` instances are defined using `(.&.)`, `(.|.)`, `xor`
and ```\x y -> complement (x `xor` y)```, respectively.
- `oneBits :: FiniteBits a => a`, `oneBits = complement zeroBits`.
## 4.15.0.0 *Feb 2021*
* `openFile` now calls the `open` system call with an `interruptible` FFI
call, ensuring that the call can be interrupted with `SIGINT` on POSIX
systems.
* Add `hGetContents'`, `getContents'`, and `readFile'` in `System.IO`:
Strict IO variants of `hGetContents`, `getContents`, and `readFile`.
* Add `singleton` function for `Data.List.NonEmpty`.
* The planned deprecation of `Data.Monoid.First` and `Data.Monoid.Last`
is scrapped due to difficulties with the suggested migration path.
* `Data.Semigroup.Option` and the accompanying `option` function are
deprecated and scheduled for removal in 4.16.
* Add `Generic` instances to `Fingerprint`, `GiveGCStats`, `GCFlags`,
`ConcFlags`, `DebugFlags`, `CCFlags`, `DoHeapProfile`, `ProfFlags`,
`DoTrace`, `TraceFlags`, `TickyFlags`, `ParFlags`, `RTSFlags`, `RTSStats`,
`GCStats`, `ByteOrder`, `GeneralCategory`, `SrcLoc`
* Add rules `unpackUtf8`, `unpack-listUtf8` and `unpack-appendUtf8` to `GHC.Base`.
They correspond to their ascii versions and hopefully make it easier
for libraries to handle utf8 encoded strings efficiently.
* An issue with list fusion and `elem` was fixed. `elem` applied to known
small lists will now compile to a simple case statement more often.
* Add `MonadFix` and `MonadZip` instances for `Complex`
* Add `Ix` instances for tuples of size 6 through 15
* Correct `Bounded` instance and remove `Enum` and `Integral` instances for
`Data.Ord.Down`.
* `catMaybes` is now implemented using `mapMaybe`, so that it is both a "good
consumer" and "good producer" for list-fusion (#18574)
* `Foreign.ForeignPtr.withForeignPtr` is now less aggressively optimised,
avoiding the soundness issue reported in
[#17760](https://gitlab.haskell.org/ghc/ghc/-/issues/17760) in exchange for
a small amount more allocation. If your application regresses significantly
*and* the continuation given to `withForeignPtr` will *not* provably
diverge then the previous optimisation behavior can be recovered by instead
using `GHC.ForeignPtr.unsafeWithForeignPtr`.
* Correct `Bounded` instance and remove `Enum` and `Integral` instances for
`Data.Ord.Down`.
* `Data.Foldable` methods `maximum{,By}`, `minimum{,By}`, `product` and `sum`
are now stricter by default, as well as in the class implementation for List.
## 4.14.0.0 *Jan 2020*
* Bundled with GHC 8.10.1
* Add a `TestEquality` instance for the `Compose` newtype.
* `Data.Ord.Down` now has a field name, `getDown`
* Add `Bits`, `Bounded`, `Enum`, `FiniteBits`, `Floating`, `Fractional`,
`Integral`, `Ix`, `Real`, `RealFrac`, `RealFloat` and `Storable` instances
to `Data.Ord.Down`.
* Fix the `integer-gmp` variant of `isValidNatural`: Previously it would fail
to detect values `<= maxBound::Word` that were incorrectly encoded using
the `NatJ#` constructor.
* The type of `coerce` has been generalized. It is now runtime-representation
polymorphic:
`forall {r :: RuntimeRep} (a :: TYPE r) (b :: TYPE r). Coercible a b => a -> b`.
The type argument `r` is marked as `Inferred` to prevent it from
interfering with visible type application.
* Make `Fixed` and `HasResolution` poly-kinded.
* Add `HasResolution` instances for `Nat`s.
* Add `Functor`, `Applicative`, `Monad`, `Alternative`, `MonadPlus`,
`Generic` and `Generic1` instances to `Kleisli`
* `openTempFile` is now fully atomic and thread-safe on Windows.
* Add `isResourceVanishedError`, `resourceVanishedErrorType`, and
`isResourceVanishedErrorType` to `System.IO.Error`.
* Add newtypes for `CSocklen` (`socklen_t`) and `CNfds` (`nfds_t`) to
`System.Posix.Types`.
* Add `Functor`, `Applicative` and `Monad` instances to `(,,) a b`
and `(,,,) a b c`.
* Add `resizeSmallMutableArray#` to `GHC.Exts`.
* Add a `Data` instance to `WrappedArrow`, `WrappedMonad`, and `ZipList`.
* Add `IsList` instance for `ZipList`.
## 4.13.0.0 *July 2019*
* Bundled with GHC 8.8.1
* The final phase of the `MonadFail` proposal has been implemented:
* The `fail` method of `Monad` has been removed in favor of the method of
the same name in the `MonadFail` class.
* `MonadFail(fail)` is now re-exported from the `Prelude` and
`Control.Monad` modules.
* Fix `Show` instance of `Data.Fixed`: Negative numbers are now parenthesized
according to their surrounding context. I.e. `Data.Fixed.show` produces
syntactically correct Haskell for expressions like `Just (-1 :: Fixed E2)`.
(#16031)
* Support the characters from recent versions of Unicode (up to v. 12) in
literals (#5518).
* The `StableName` type parameter now has a phantom role instead of
a representational one. There is really no reason to care about the
type of the underlying object.
* Add `foldMap'`, a strict version of `foldMap`, to `Foldable`.
* The `shiftL` and `shiftR` methods in the `Bits` instances of `Int`, `IntN`,
`Word`, and `WordN` now throw an overflow exception for negative shift
values (instead of being undefined behaviour).
* `scanr` no longer crashes when passed a fusable, infinite list. (#16943)
## 4.12.0.0 *21 September 2018*
* Bundled with GHC 8.6.1
* The STM invariant-checking mechanism (`always` and `alwaysSucceeds`), which
was deprecated in GHC 8.4, has been removed (as proposed in
).
This is a bit earlier than proposed in the deprecation pragma included in
GHC 8.4, but due to community feedback we decided to move ahead with the
early removal.
Existing users are encouraged to encapsulate their STM operations in safe
abstractions which can perform the invariant checking without help from the
runtime system.
* Add a new module `GHC.ResponseFile` (previously defined in the `haddock`
package). (#13896)
* Move the module `Data.Functor.Contravariant` from the
`contravariant` package to `base`.
* `($!)` is now representation-polymorphic like `($)`.
* Add `Applicative` (for `K1`), `Semigroup` and `Monoid` instances in
`GHC.Generics`. (#14849)
* `asinh` for `Float` and `Double` is now numerically stable in the face of
non-small negative arguments and enormous arguments of either sign. (#14927)
* `Numeric.showEFloat (Just 0)` now respects the user's requested precision.
(#15115)
* `Data.Monoid.Alt` now has `Foldable` and `Traversable` instances. (#15099)
* `Data.Monoid.Ap` has been introduced
* `Control.Exception.throw` is now levity polymorphic. (#15180)
* `Data.Ord.Down` now has a number of new instances. These include:
`MonadFix`, `MonadZip`, `Data`, `Foldable`, `Traversable`, `Eq1`, `Ord1`,
`Read1`, `Show1`, `Generic`, `Generic1`. (#15098)
## 4.11.1.0 *19 April 2018*
* Bundled with GHC 8.4.2
* Add the `readFieldHash` function to `GHC.Read` which behaves like
`readField`, but for a field that ends with a `#` symbol (#14918).
## 4.11.0.0 *8 March 2018*
* Bundled with GHC 8.4.1
* `System.IO.openTempFile` is now thread-safe on Windows.
* Deprecated `GHC.Stats.GCStats` interface has been removed.
* Add `showHFloat` to `Numeric`
* Add `Div`, `Mod`, and `Log2` functions on type-level naturals
in `GHC.TypeLits`.
* Add `Alternative` instance for `ZipList` (#13520)
* Add instances `Num`, `Functor`, `Applicative`, `Monad`, `Semigroup`
and `Monoid` for `Data.Ord.Down` (#13097).
* Add `Semigroup` instance for `EventLifetime`.
* Make `Semigroup` a superclass of `Monoid`;
export `Semigroup((<>))` from `Prelude`; remove `Monoid` reexport
from `Data.Semigroup` (#14191).
* Generalise `instance Monoid a => Monoid (Maybe a)` to
`instance Semigroup a => Monoid (Maybe a)`.
* Add `infixl 9 !!` declaration for `Data.List.NonEmpty.!!`
* Add `<&>` operator to `Data.Functor` (#14029)
* Remove the deprecated `Typeable{1..7}` type synonyms (#14047)
* Make `Data.Type.Equality.==` a closed type family. It now works for all
kinds out of the box. Any modules that previously declared instances of this
family will need to remove them. Whereas the previous definition was somewhat
ad hoc, the behavior is now completely uniform. As a result, some applications
that used to reduce no longer do, and conversely. Most notably, `(==)` no
longer treats the `*`, `j -> k`, or `()` kinds specially; equality is
tested structurally in all cases.
* Add instances `Semigroup` and `Monoid` for `Control.Monad.ST` (#14107).
* The `Read` instances for `Proxy`, `Coercion`, `(:~:)`, `(:~~:)`, and `U1`
now ignore the parsing precedence. The effect of this is that `read` will
be able to successfully parse more strings containing `"Proxy"` _et al._
without surrounding parentheses (e.g., `"Thing Proxy"`) (#12874).
* Add `iterate'`, a strict version of `iterate`, to `Data.List`
and `Data.OldList` (#3474)
* Add `Data` instances for `IntPtr` and `WordPtr` (#13115)
* Add missing `MonadFail` instance for `Control.Monad.Strict.ST.ST`
* Make `zipWith` and `zipWith3` inlinable (#14224)
* `Type.Reflection.App` now matches on function types (fixes #14236)
* `Type.Reflection.withTypeable` is now polymorphic in the `RuntimeRep` of
its result.
* Add `installSEHHandlers` to `MiscFlags` in `GHC.RTS.Flags` to determine if
exception handling is enabled.
* The deprecated functions `isEmptyChan` and `unGetChan` in
`Control.Concurrent.Chan` have been removed (#13561).
* Add `generateCrashDumpFile` to `MiscFlags` in `GHC.RTS.Flags` to determine
if a core dump will be generated on crashes.
* Add `generateStackTrace` to `MiscFlags` in `GHC.RTS.Flags` to determine if
stack traces will be generated on unhandled exceptions by the RTS.
* `getExecutablePath` now resolves symlinks on Windows (#14483)
* Deprecated STM invariant checking primitives (`checkInv`, `always`, and
`alwaysSucceeds`) in `GHC.Conc.Sync` (#14324).
* Add a `FixIOException` data type to `Control.Exception.Base`, and change
`fixIO` to throw that instead of a `BlockedIndefinitelyOnMVar` exception
(#14356).
## 4.10.1.0 *November 2017*
* Bundled with GHC 8.2.2
* The file locking primitives provided by `GHC.IO.Handle` now use
Linux open file descriptor locking if available.
* Fixed bottoming definition of `clearBit` for `Natural`
## 4.10.0.0 *July 2017*
* Bundled with GHC 8.2.1
* `Data.Type.Bool.Not` given a type family dependency (#12057).
* `Foreign.Ptr` now exports the constructors for `IntPtr` and `WordPtr`
(#11983)
* `Generic1`, as well as the associated datatypes and typeclasses in
`GHC.Generics`, are now poly-kinded (#10604)
* `New modules `Data.Bifoldable` and `Data.Bitraversable` (previously defined
in the `bifunctors` package) (#10448)
* `Data.Either` now provides `fromLeft` and `fromRight` (#12402)
* `Data.Type.Coercion` now provides `gcoerceWith` (#12493)
* New methods `liftReadList(2)` and `liftReadListPrec(2)` in the
`Read1`/`Read2` classes that are defined in terms of `ReadPrec` instead of
`ReadS`, as well as related combinators, have been added to
`Data.Functor.Classes` (#12358)
* Add `Semigroup` instance for `IO`, as well as for `Event` and `Lifetime`
from `GHC.Event` (#12464)
* Add `Data` instance for `Const` (#12438)
* Added `Eq1`, `Ord1`, `Read1` and `Show1` instances for `NonEmpty`.
* Add wrappers for `blksize_t`, `blkcnt_t`, `clockid_t`, `fsblkcnt_t`,
`fsfilcnt_t`, `id_t`, `key_t`, and `timer_t` to System.Posix.Types (#12795)
* Add `CBool`, a wrapper around C's `bool` type, to `Foreign.C.Types`
(#13136)
* Raw buffer operations in `GHC.IO.FD` are now strict in the buffer, offset, and length operations (#9696)
* Add `plusForeignPtr` to `Foreign.ForeignPtr`.
* Add `type family AppendSymbol (m :: Symbol) (n :: Symbol) :: Symbol` to `GHC.TypeLits`
(#12162)
* Add `GHC.TypeNats` module with `Natural`-based `KnownNat`. The `Nat`
operations in `GHC.TypeLits` are a thin compatibility layer on top.
Note: the `KnownNat` evidence is changed from an `Integer` to a `Natural`.
* The type of `asProxyTypeOf` in `Data.Proxy` has been generalized (#12805)
* `liftA2` is now a method of the `Applicative` class. `liftA2` and
`<*>` each have a default implementation based on the other. Various
library functions have been updated to use `liftA2` where it might offer
some benefit. `liftA2` is not yet in the `Prelude`, and must currently be
imported from `Control.Applicative`. It is likely to be added to the
`Prelude` in the future. (#13191)
* A new module, `Type.Reflection`, exposing GHC's new type-indexed type
representation mechanism is now provided.
* `Data.Dynamic` now exports the `Dyn` data constructor, enabled by the new
type-indexed type representation mechanism.
* `Data.Type.Equality` now provides a kind heterogeneous type equality
evidence type, `(:~~:)`.
* The `CostCentresXML` constructor of `GHC.RTS.Flags.DoCostCentres` has been
replaced by `CostCentresJSON` due to the new JSON export format supported by
the cost centre profiler.
* The `ErrorCall` pattern synonym has been given a `COMPLETE` pragma so that
functions which solely match again `ErrorCall` do not produce
non-exhaustive pattern-match warnings (#8779)
* Change the implementations of `maximumBy` and `minimumBy` from
`Data.Foldable` to use `foldl1` instead of `foldr1`. This makes them run
in constant space when applied to lists. (#10830)
* `mkFunTy`, `mkAppTy`, and `mkTyConApp` from `Data.Typeable` no longer exist.
This functionality is superceded by the interfaces provided by
`Type.Reflection`.
* `mkTyCon3` is no longer exported by `Data.Typeable`. This function is
replaced by `Type.Reflection.Unsafe.mkTyCon`.
* `Data.List.NonEmpty.unfold` has been deprecated in favor of `unfoldr`,
which is functionally equivalent.
## 4.9.0.0 *May 2016*
* Bundled with GHC 8.0
* `error` and `undefined` now print a partial stack-trace alongside the error message.
* New `errorWithoutStackTrace` function throws an error without printing the stack trace.
* The restore operation provided by `mask` and `uninterruptibleMask` now
restores the previous masking state whatever the current masking state is.
* New `GHC.Generics.packageName` operation
* Redesigned `GHC.Stack.CallStack` data type. As a result, `CallStack`'s
`Show` instance produces different output, and `CallStack` no longer has an
`Eq` instance.
* New `GHC.Generics.packageName` operation
* New `GHC.Stack.Types` module now contains the definition of
`CallStack` and `SrcLoc`
* New `GHC.Stack.Types.emptyCallStack` function builds an empty `CallStack`
* New `GHC.Stack.Types.freezeCallStack` function freezes a `CallStack` preventing future `pushCallStack` operations from having any effect
* New `GHC.Stack.Types.pushCallStack` function pushes a call-site onto a `CallStack`
* New `GHC.Stack.Types.fromCallSiteList` function creates a `CallStack` from
a list of call-sites (i.e., `[(String, SrcLoc)]`)
* `GHC.SrcLoc` has been removed
* `GHC.Stack.showCallStack` and `GHC.SrcLoc.showSrcLoc` are now called
`GHC.Stack.prettyCallStack` and `GHC.Stack.prettySrcLoc` respectively
* add `Data.List.NonEmpty` and `Data.Semigroup` (to become
super-class of `Monoid` in the future). These modules were
provided by the `semigroups` package previously. (#10365)
* Add `selSourceUnpackedness`, `selSourceStrictness`, and
`selDecidedStrictness`, three functions which look up strictness
information of a field in a data constructor, to the `Selector` type class
in `GHC.Generics` (#10716)
* Add `URec`, `UAddr`, `UChar`, `UDouble`, `UFloat`, `UInt`, and `UWord` to
`GHC.Generics` as part of making GHC generics capable of handling
unlifted types (#10868)
* The `Eq`, `Ord`, `Read`, and `Show` instances for `U1` now use lazier
pattern-matching
* Keep `shift{L,R}` on `Integer` with negative shift-arguments from
segfaulting (#10571)
* Add `forkOSWithUnmask` to `Control.Concurrent`, which is like
`forkIOWithUnmask`, but the child is run in a bound thread.
* The `MINIMAL` definition of `Arrow` is now `arr AND (first OR (***))`.
* The `MINIMAL` definition of `ArrowChoice` is now `left OR (+++)`.
* Exported `GiveGCStats`, `DoCostCentres`, `DoHeapProfile`, `DoTrace`,
`RtsTime`, and `RtsNat` from `GHC.RTS.Flags`
* New function `GHC.IO.interruptible` used to correctly implement
`Control.Exception.allowInterrupt` (#9516)
* Made `PatternMatchFail`, `RecSelError`, `RecConError`, `RecUpdError`,
`NoMethodError`, and `AssertionFailed` newtypes (#10738)
* New module `Control.Monad.IO.Class` (previously provided by `transformers`
package). (#10773)
* New modules `Data.Functor.Classes`, `Data.Functor.Compose`,
`Data.Functor.Product`, and `Data.Functor.Sum` (previously provided by
`transformers` package). (#11135)
* New instances for `Proxy`: `Eq1`, `Ord1`, `Show1`, `Read1`. All
of the classes are from `Data.Functor.Classes` (#11756).
* New module `Control.Monad.Fail` providing new `MonadFail(fail)`
class (#10751)
* Add `GHC.TypeLits.TypeError` and `ErrorMessage` to allow users
to define custom compile-time error messages.
* Redesign `GHC.Generics` to use type-level literals to represent the
metadata of generic representation types (#9766)
* The `IsString` instance for `[Char]` has been modified to eliminate
ambiguity arising from overloaded strings and functions like `(++)`.
* Move `Const` from `Control.Applicative` to its own module in
`Data.Functor.Const`. (#11135)
* Re-export `Const` from `Control.Applicative` for backwards compatibility.
* Expand `Floating` class to include operations that allow for better
precision: `log1p`, `expm1`, `log1pexp` and `log1mexp`. These are not
available from `Prelude`, but the full class is exported from `Numeric`.
* New `Control.Exception.TypeError` datatype, which is thrown when an
expression fails to typecheck when run using `-fdefer-type-errors` (#10284)
* The `bitSize` method of `Data.Bits.Bits` now has a (partial!)
default implementation based on `bitSizeMaybe`. (#12970)
### New instances
* `Alt`, `Dual`, `First`, `Last`, `Product`, and `Sum` now have `Data`,
`MonadZip`, and `MonadFix` instances
* The datatypes in `GHC.Generics` now have `Enum`, `Bounded`, `Ix`,
`Functor`, `Applicative`, `Monad`, `MonadFix`, `MonadPlus`, `MonadZip`,
`Foldable`, `Foldable`, `Traversable`, `Generic1`, and `Data` instances
as appropriate.
* `Maybe` now has a `MonadZip` instance
* `All` and `Any` now have `Data` instances
* `Dual`, `First`, `Last`, `Product`, and `Sum` now have `Foldable` and
`Traversable` instances
* `Dual`, `Product`, and `Sum` now have `Functor`, `Applicative`, and
`Monad` instances
* `(,) a` now has a `Monad` instance
* `ZipList` now has `Foldable` and `Traversable` instances
* `Identity` now has `Semigroup` and `Monoid` instances
* `Identity` and `Const` now have `Bits`, `Bounded`, `Enum`, `FiniteBits`,
`Floating`, `Fractional`, `Integral`, `IsString`, `Ix`, `Num`, `Real`,
`RealFloat`, `RealFrac` and `Storable` instances. (#11210, #11790)
* `()` now has a `Storable` instance
* `Complex` now has `Generic`, `Generic1`, `Functor`, `Foldable`, `Traversable`,
`Applicative`, and `Monad` instances
* `System.Exit.ExitCode` now has a `Generic` instance
* `Data.Version.Version` now has a `Generic` instance
* `IO` now has a `Monoid` instance
* Add `MonadPlus IO` and `Alternative IO` instances
(previously orphans in `transformers`) (#10755)
* `CallStack` now has an `IsList` instance
* The field `spInfoName` of `GHC.StaticPtr.StaticPtrInfo` has been removed.
The value is no longer available when constructing the `StaticPtr`.
* `VecElem` and `VecCount` now have `Enum` and `Bounded` instances.
### Generalizations
* Generalize `Debug.Trace.{traceM, traceShowM}` from `Monad` to `Applicative`
(#10023)
* Redundant typeclass constraints have been removed:
- `Data.Ratio.{denominator,numerator}` have no `Integral` constraint anymore
- **TODO**
* Generalise `forever` from `Monad` to `Applicative`
* Generalize `filterM`, `mapAndUnzipM`, `zipWithM`, `zipWithM_`, `replicateM`,
`replicateM_` from `Monad` to `Applicative` (#10168)
* The `Generic` instance for `Proxy` is now poly-kinded (#10775)
* Enable `PolyKinds` in the `Data.Functor.Const` module to give `Const`
the kind `* -> k -> *`. (#10039)
## 4.8.2.0 *Oct 2015*
* Bundled with GHC 7.10.3
* The restore operation provided by `mask` and `uninterruptibleMask` now
restores the previous masking state whatever the current masking state is.
* Exported `GiveGCStats`, `DoCostCentres`, `DoHeapProfile`, `DoTrace`,
`RtsTime`, and `RtsNat` from `GHC.RTS.Flags`
## 4.8.1.0 *Jul 2015*
* Bundled with GHC 7.10.2
* `Lifetime` is now exported from `GHC.Event`
* Implicit-parameter based source location support exposed in `GHC.SrcLoc` and `GHC.Stack`.
See GHC User's Manual for more information.
## 4.8.0.0 *Mar 2015*
* Bundled with GHC 7.10.1
* Make `Applicative` a superclass of `Monad`
* Add reverse application operator `Data.Function.(&)`
* Add `Data.List.sortOn` sorting function
* Add `System.Exit.die`
* Deprecate `versionTags` field of `Data.Version.Version`.
Add `makeVersion :: [Int] -> Version` constructor function to aid
migration to a future `versionTags`-less `Version`.
* Add `IsList Version` instance
* Weaken RealFloat constraints on some `Data.Complex` functions
* Add `Control.Monad.(<$!>)` as a strict version of `(<$>)`
* The `Data.Monoid` module now has the `PolyKinds` extension
enabled, so that the `Monoid` instance for `Proxy` are polykinded
like `Proxy` itself is.
* Make `abs` and `signum` handle (-0.0) correctly per IEEE-754.
* Re-export `Data.Word.Word` from `Prelude`
* Add `countLeadingZeros` and `countTrailingZeros` methods to
`Data.Bits.FiniteBits` class
* Add `Data.List.uncons` list destructor (#9550)
* Export `Monoid(..)` from `Prelude`
* Export `Foldable(..)` from `Prelude`
(hiding `fold`, `foldl'`, `foldr'`, and `toList`)
* Export `Traversable(..)` from `Prelude`
* Set fixity for `Data.Foldable.{elem,notElem}` to match the
conventional one set for `Data.List.{elem,notElem}` (#9610)
* Turn `toList`, `elem`, `sum`, `product`, `maximum`, and `minimum`
into `Foldable` methods (#9621)
* Replace the `Data.List`-exported functions
```
all, and, any, concat, concatMap, elem, find, product, sum,
mapAccumL, mapAccumR
```
by re-exports of their generalised `Data.Foldable`/`Data.Traversable`
counterparts. In other words, unqualified imports of `Data.List`
and `Data.Foldable`/`Data.Traversable` no longer lead to conflicting
definitions. (#9586)
* New (unofficial) module `GHC.OldList` containing only list-specialised
versions of the functions from `Data.List` (in other words, `GHC.OldList`
corresponds to `base-4.7.0.2`'s `Data.List`)
* Replace the `Control.Monad`-exported functions
```
sequence_, msum, mapM_, forM_,
forM, mapM, sequence
```
by re-exports of their generalised `Data.Foldable`/`Data.Traversable`
counterparts. In other words, unqualified imports of `Control.Monad`
and `Data.Foldable`/`Data.Traversable` no longer lead to conflicting
definitions. (#9586)
* Generalise `Control.Monad.{when,unless,guard}` from `Monad` to
`Applicative` and from `MonadPlus` to `Alternative` respectively.
* Generalise `Control.Monad.{foldM,foldM_}` to `Foldable`
* `scanr`, `mapAccumL` and `filterM` now take part in list fusion (#9355,
#9502, #9546)
* Remove deprecated `Data.OldTypeable` (#9639)
* New module `Data.Bifunctor` providing the `Bifunctor(bimap,first,second)`
class (previously defined in `bifunctors` package) (#9682)
* New module `Data.Void` providing the canonical uninhabited type `Void`
(previously defined in `void` package) (#9814)
* Update Unicode class definitions to Unicode version 7.0
* Add `Alt`, an `Alternative` wrapper, to `Data.Monoid`. (#9759)
* Add `isSubsequenceOf` to `Data.List` (#9767)
* The arguments to `==` and `eq` in `Data.List.nub` and `Data.List.nubBy`
are swapped, such that `Data.List.nubBy (<) [1,2]` now returns `[1]`
instead of `[1,2]` (#2528, #3280, #7913)
* New module `Data.Functor.Identity` (previously provided by `transformers`
package). (#9664)
* Add `scanl'`, a strictly accumulating version of `scanl`, to `Data.List`
and `Data.OldList`. (#9368)
* Add `fillBytes` to `Foreign.Marshal.Utils`.
* Add new `displayException` method to `Exception` typeclass. (#9822)
* Add `Data.Bits.toIntegralSized`, a size-checked version of
`fromIntegral`. (#9816)
* New module `Numeric.Natural` providing new `Natural` type
representing non-negative arbitrary-precision integers. The `GHC.Natural`
module exposes additional GHC-specific primitives. (#9818)
* Add `(Storable a, Integeral a) => Storable (Ratio a)` instance (#9826)
* Add `Storable a => Storable (Complex a)` instance (#9826)
* New module `GHC.RTS.Flags` that provides accessors to runtime flags.
* Expose functions for per-thread allocation counters and limits in `GHC.Conc`
disableAllocationLimit :: IO ()
enableAllocationLimit :: IO ()
getAllocationCounter :: IO Int64
setAllocationCounter :: Int64 -> IO ()
together with a new exception `AllocationLimitExceeded`.
* Make `read . show = id` for `Data.Fixed` (#9240)
* Add `calloc` and `callocBytes` to `Foreign.Marshal.Alloc`. (#9859)
* Add `callocArray` and `callocArray0` to `Foreign.Marshal.Array`. (#9859)
* Restore invariant in `Data (Ratio a)` instance (#10011)
* Add/expose `rnfTypeRep`, `rnfTyCon`, `typeRepFingerprint`, and
`tyConFingerprint` helpers to `Data.Typeable`.
* Define proper `MINIMAL` pragma for `class Ix`. (#10142)
## 4.7.0.2 *Dec 2014*
* Bundled with GHC 7.8.4
* Fix performance bug in `Data.List.inits` (#9345)
* Fix handling of null bytes in `Debug.Trace.trace` (#9395)
## 4.7.0.1 *Jul 2014*
* Bundled with GHC 7.8.3
* Unhide `Foreign.ForeignPtr` in Haddock (#8475)
* Fix recomputation of `TypeRep` in `Typeable` type-application instance
(#9203)
* Fix regression in Data.Fixed Read instance (#9231)
* Fix `fdReady` to honor `FD_SETSIZE` (#9168)
## 4.7.0.0 *Apr 2014*
* Bundled with GHC 7.8.1
* Add `/Since: 4.[4567].0.0/` Haddock annotations to entities
denoting the package version, when the given entity was introduced
(or its type signature changed in a non-compatible way)
* The `Control.Category` module now has the `PolyKinds` extension
enabled, meaning that instances of `Category` no longer need be of
kind `* -> * -> *`.
* There are now `Foldable` and `Traversable` instances for `Either a`,
`Const r`, and `(,) a`.
* There are now `Show`, `Read`, `Eq`, `Ord`, `Monoid`, `Generic`, and
`Generic1` instances for `Const`.
* There is now a `Data` instance for `Data.Version`.
* A new `Data.Bits.FiniteBits` class has been added to represent
types with fixed bit-count. The existing `Bits` class is extended
with a `bitSizeMaybe` method to replace the now obsolete
`bitsize` method.
* `Data.Bits.Bits` gained a new `zeroBits` method which completes the
`Bits` API with a direct way to introduce a value with all bits cleared.
* There are now `Bits` and `FiniteBits` instances for `Bool`.
* There are now `Eq`, `Ord`, `Show`, `Read`, `Generic`. and `Generic1`
instances for `ZipList`.
* There are now `Eq`, `Ord`, `Show` and `Read` instances for `Down`.
* There are now `Eq`, `Ord`, `Show`, `Read` and `Generic` instances
for types in GHC.Generics (`U1`, `Par1`, `Rec1`, `K1`, `M1`,
`(:+:)`, `(:*:)`, `(:.:)`).
* `Data.Monoid`: There are now `Generic` instances for `Dual`, `Endo`,
`All`, `Any`, `Sum`, `Product`, `First`, and `Last`; as well as
`Generic1` instances for `Dual`, `Sum`, `Product`, `First`, and `Last`.
* The `Data.Monoid.{Product,Sum}` newtype wrappers now have `Num` instances.
* There are now `Functor` instances for `System.Console.GetOpt`'s
`ArgOrder`, `OptDescr`, and `ArgDescr`.
* A zero-width unboxed poly-kinded `Proxy#` was added to
`GHC.Prim`. It can be used to make it so that there is no the
operational overhead for passing around proxy arguments to model
type application.
* New `Data.Proxy` module providing a concrete, poly-kinded proxy type.
* New `Data.Coerce` module which exports the new `Coercible` class
together with the `coerce` primitive which provide safe coercion
(wrt role checking) between types with same representation.
* `Control.Concurrent.MVar` has a new implementation of `readMVar`,
which fixes a long-standing bug where `readMVar` is only atomic if
there are no other threads running `putMVar`. `readMVar` now is
atomic, and is guaranteed to return the value from the first
`putMVar`. There is also a new `tryReadMVar` which is a
non-blocking version.
* New `Control.Concurrent.MVar.withMVarMasked` which executes
`IO` action with asynchronous exceptions masked in the same style
as the existing `modifyMVarMasked` and `modifyMVarMasked_`.
* New `threadWait{Read,Write}STM :: Fd -> IO (STM (), IO ())`
functions added to `Control.Concurrent` for waiting on FD
readiness with STM actions.
* Expose `Data.Fixed.Fixed`'s constructor.
* There are now byte endian-swapping primitives
`byteSwap{16,32,64}` available in `Data.Word`, which use
optimized machine instructions when available.
* `Data.Bool` now exports `bool :: a -> a -> Bool -> a`, analogously
to `maybe` and `either` in their respective modules.
* `Data.Either` now exports `isLeft, isRight :: Either a b -> Bool`.
* `Debug.Trace` now exports `traceId`, `traceShowId`, `traceM`,
and `traceShowM`.
* `Data.Functor` now exports `($>)` and `void`.
* Rewrote portions of `Text.Printf`, and made changes to `Numeric`
(added `Numeric.showFFloatAlt` and `Numeric.showGFloatAlt`) and
`GHC.Float` (added `formatRealFloatAlt`) to support it. The
rewritten version is extensible to user types, adds a "generic"
format specifier "`%v`", extends the `printf` spec to support much
of C's `printf(3)` functionality, and fixes the spurious warnings
about using `Text.Printf.printf` at `(IO a)` while ignoring the
return value. These changes were contributed by Bart Massey.
* The minimal complete definitions for all type-classes with cyclic
default implementations have been explicitly annotated with the
new `{-# MINIMAL #-}` pragma.
* `Control.Applicative.WrappedMonad`, which can be used to convert a
`Monad` to an `Applicative`, has now a
`Monad m => Monad (WrappedMonad m)` instance.
* There is now a `Generic` and a `Generic1` instance for `WrappedMonad`
and `WrappedArrow`.
* Handle `ExitFailure (-sig)` on Unix by killing process with signal `sig`.
* New module `Data.Type.Bool` providing operations on type-level booleans.
* Expose `System.Mem.performMinorGC` for triggering minor GCs.
* New `System.Environment.{set,unset}Env` for manipulating
environment variables.
* Add `Typeable` instance for `(->)` and `RealWorld`.
* Declare CPP header `` officially obsolete as GHC 7.8+
does not support hand-written `Typeable` instances anymore.
* Remove (unmaintained) Hugs98 and NHC98 specific code.
* Optimize `System.Timeout.timeout` for the threaded RTS.
* Remove deprecated functions `unsafeInterleaveST`, `unsafeIOToST`,
and `unsafeSTToIO` from `Control.Monad.ST`.
* Add a new superclass `SomeAsyncException` for all asynchronous exceptions
and makes the existing `AsyncException` and `Timeout` exception children
of `SomeAsyncException` in the hierarchy.
* Remove deprecated functions `blocked`, `unblock`, and `block` from
`Control.Exception`.
* Remove deprecated function `forkIOUnmasked` from `Control.Concurrent`.
* Remove deprecated function `unsafePerformIO` export from `Foreign`
(still available via `System.IO.Unsafe.unsafePerformIO`).
* Various fixes and other improvements (see Git history for full details).