stgi-1.0.1: Educational implementation of the STG (Spineless Tagless G-machine)

Safe Haskell	None
Language	Haskell2010

Stg.Machine

Contents

Evaluation
Garbage collection

Description

User-facing API to work with STG programs.

Synopsis

Documentation

initialState Source

Arguments

:: Var	Main
-> Program
-> StgState

Create a suitable initial state for an STG.

Evaluation

evalStep :: StgState -> StgState Source

Perform a single STG machine evaluation step.

evalUntil Source

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

evalsUntil Source

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 ≈ unfoldr evalUntil

terminated :: StgState -> Bool Source

Check whether a state is terminal.

newtype HaltIf Source

Predicate to decide whether the machine should halt.

Constructors

HaltIf (StgState -> Bool)

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

newtype PerformGc Source

Decide whether garbage collection should be attempted, and with which algorithm.

Constructors

PerformGc (StgState -> Maybe GarbageCollectionAlgorithm)

data GarbageCollectionAlgorithm Source

triStateTracing :: GarbageCollectionAlgorithm Source

Remove all unused addresses, without moving the others.

twoSpaceCopying :: GarbageCollectionAlgorithm Source

Remove all unused addresses by moving them to a safe location.