| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Stg.Machine
Contents
Description
User-facing API to work with STG programs.
- initialState :: Var -> Program -> StgState
- evalStep :: StgState -> StgState
- evalUntil :: RunForSteps -> HaltIf -> PerformGc -> StgState -> StgState
- evalsUntil :: RunForSteps -> HaltIf -> PerformGc -> StgState -> NonEmpty StgState
- terminated :: StgState -> Bool
- newtype HaltIf = HaltIf (StgState -> Bool)
- data RunForSteps
- garbageCollect :: GarbageCollectionAlgorithm -> StgState -> StgState
- newtype PerformGc = PerformGc (StgState -> Maybe GarbageCollectionAlgorithm)
- data GarbageCollectionAlgorithm
- triStateTracing :: GarbageCollectionAlgorithm
- twoSpaceCopying :: GarbageCollectionAlgorithm
Documentation
Create a suitable initial state for an STG.
Evaluation
Arguments
| :: RunForSteps | Maximum number of steps allowed |
| -> HaltIf | Halting decision function |
| -> PerformGc | Condition under which to perform GC |
| -> StgState | Initial state |
| -> StgState | Final state |
Evaluate the STG until a predicate holds, aborting if the maximum number of steps are exceeded.
last(evalsUntil...) ≡evalUntil
Arguments
| :: RunForSteps | Maximum number of steps allowed |
| -> HaltIf | Halting decision function |
| -> PerformGc | Condition under which to perform GC |
| -> StgState | Initial state |
| -> NonEmpty StgState | Initial state plus intermediate states |
Evaluate the STG, and record all intermediate states.
- Stop when a predicate holds.
- Stop if the maximum number of steps are exceeded.
- Perform GC on every step.
evalsUntil≈unfoldrevalUntil
terminated :: StgState -> Bool Source #
Check whether a state is terminal.
Predicate to decide whether the machine should halt.
data RunForSteps Source #
Predicate to decide whether the machine should halt.
Constructors
| RunIndefinitely | Do not terminate based on the number of steps |
| RunForMaxSteps Integer |
Garbage collection
garbageCollect :: GarbageCollectionAlgorithm -> StgState -> StgState Source #
Apply a garbage collection algorithm to the heap of the current machine state, and return the resulting cleaned state.
Decide whether garbage collection should be attempted, and with which algorithm.
Constructors
| PerformGc (StgState -> Maybe GarbageCollectionAlgorithm) |
data GarbageCollectionAlgorithm Source #
A garbage collection algorithm is a specific way to get rid of unused heap objects.
triStateTracing :: GarbageCollectionAlgorithm Source #
Remove all unused addresses, without moving the others.
twoSpaceCopying :: GarbageCollectionAlgorithm Source #
Move all used addresses by moving them to a safe location, and delete the leftovers.