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GHC 9.10.3 · lts/ghc-9.10.x · c74966e · 2026-09-27

Modulebase-4.20.2.0Haskell2010

GHC.RTS.Flags

The API of this module is unstable and is tightly coupled to GHC's internals. If depend on it, make sure to use a tight upper bound, e.g., base < 4.X rather than base < 5, because the interface can change rapidly without much warning.

Descriptions of flags can be seen in GHC User's Guide, or by running RTS help message using +RTS --help.

  • 17 types
  • 12 values
  • Packagebase-4.20.2.0
  • Exports29
  • LanguageHaskell2010
  • LicenceBSD-3-Clause
  • SourceFlags.hs
datadata RTSFlags
#
Instances3Show, Generic, Rep
datadata GiveGCStats
#

Should we produce a summary of the garbage collector statistics after the program has exited?

Instances4Enum, Show, Generic, Rep
datadata GCFlags
#
Instances3Show, Generic, Rep
datadata ConcFlags
#

Parameters concerning context switching

Instances3Show, Generic, Rep
datadata MiscFlags
#
Instances3Show, Generic, Rep
datadata DebugFlags
#

Flags to control debugging output & extra checking in various subsystems.

Constructors

Instances3Show, Generic, Rep
datadata DoCostCentres
#
Instances4Enum, Show, Generic, Rep
datadata CCFlags
#

Parameters pertaining to the cost-center profiler.

Instances3Show, Generic, Rep
datadata DoHeapProfile
#
Instances4Enum, Show, Generic, Rep
datadata ProfFlags
#
Instances3Show, Generic, Rep
datadata DoTrace
#

Is event tracing enabled?

Constructors

Instances4Enum, Show, Generic, Rep
datadata TraceFlags
#

Parameters pertaining to event tracing

Constructors

Instances3Show, Generic, Rep
datadata TickyFlags
#

Parameters pertaining to ticky-ticky profiler

Instances3Show, Generic, Rep
datadata ParFlags
#
Instances3Show, Generic, Rep
datadata HpcFlags
#

Parameters pertaining to Haskell program coverage (HPC)

Constructors

Instances3Show, Generic, Rep
datadata IoSubSystem
#

The I/O SubSystem to use in the program.

Constructors

  • IoPOSIX

    Use a POSIX I/O Sub-System

  • IoNative

    Use platform native Sub-System. For unix OSes this is the same as IoPOSIX, but on Windows this means use the Windows native APIs for I/O, including IOCP and RIO.

Instances4Enum, Eq, Show, Storable

Needed to optimize support for different IO Managers on Windows. See Note [The need for getIoManagerFlag]