Safe Haskell	None
Language	Haskell2010

Stg.Machine.Types

Contents

State information

Description

Types used in the execution of the STG machine.

Synopsis

Documentation

data StgState Source

The internal state of an STG.

Constructors

StgState

Fields

stgCode :: Code: Operation the STG should perform next
stgStack :: Stack StackFrame: The stack stores not-yet-used arguments (argument stack part), computations to return to once case evaluation has finished (return stack part), and instructions to update heap entries once computation of a certain value is done.
stgHeap :: Heap: The heap stores values allocated at the top level or in let(rec) expressions.
stgGlobals :: Globals: The environment consisting of the top-level definitions.
stgSteps :: !Integer: A counter, used to generte fresh variable names from.
stgInfo :: Info: Information about the current state

Instances

Eq StgState Source
Ord StgState Source
Show StgState Source
Generic StgState Source
Pretty StgState Source
NFData StgState Source
type Rep StgState Source

data StgStateStyle Source

Package of style definitions used in this module.

Constructors

StgStateStyle

Fields

headline :: Doc -> Doc: Style of headlines in the state overview, such as "Heap" and "Frame i".
address :: Doc -> Doc: Style of memory addresses, including 0x prefix.
addressCore :: Doc -> Doc: Style of memory addresses; applied only to the actual address number, such as ff in 0xff.
closureType :: Doc -> Doc: Style of the type of a closure, such as BLACKHOLE or FUN.
stackFrameType :: Doc -> Doc: Style of the stack frame annotation, such as UPD or ARG.

data StackFrame Source

Constructors

ArgumentFrame Value	Argument frames store values on the argument stack, so that they can later be retrieved when the calling function can be applied to them.
ReturnFrame Alts Locals	Return frames are used when the scrutinee of a case expression is done being evaluated, and the branch to continue on has to be decided.
UpdateFrame MemAddr	When an updatable closure is entered, an update frame with its heap address is created. Once its computation finishes, its heap entry is updated with the computed value.

newtype MemAddr Source

A memory address.

Constructors

MemAddr Int

data Value Source

A value of the STG machine.

Constructors

Addr MemAddr
PrimInt Integer

Instances

Eq Value Source
Ord Value Source
Show Value Source
Generic Value Source
Pretty Value Source
NFData Value Source
UpdateAddrs Value Source
Addresses Value Source
type Rep Value Source

data Code Source

The different code states the STG can be in.

Constructors

Eval Expr Locals	Evaluate an expression within a local environment
Enter MemAddr	Load the closure at a certain heap address
ReturnCon Constr [Value]	Sub-computation terminated with algebraic constructor
ReturnInt Integer	Sub-computation terminated with a primitive integer

Instances

Eq Code Source
Ord Code Source
Show Code Source
Generic Code Source
Pretty Code Source
NFData Code Source
UpdateAddrs Code Source
Addresses Code Source
type Rep Code Source

data Mapping k v Source

A single key -> value association.

Used to make 2-tuples to be inserted into association maps clearer.

Constructors

Mapping k v

Instances

(Eq k, Eq v) => Eq (Mapping k v) Source
(Ord k, Ord v) => Ord (Mapping k v) Source
(Show k, Show v) => Show (Mapping k v) Source
Generic (Mapping k v) Source
(Pretty k, Pretty v) => Pretty (Mapping k v) Source
(NFData k, NFData v) => NFData (Mapping k v) Source
type Rep (Mapping k v) Source

newtype Globals Source

The global environment consists of the mapping from top-level definitions to their respective values.

Constructors

Globals (Map Var Value)

newtype Locals Source

The global environment consists if the mapping from local definitions to their respective values.

Constructors

Locals (Map Var Value)

data Closure Source

A closure is a lambda form, together with the values of its free variables.

Constructors

Closure LambdaForm [Value]

Instances

Eq Closure Source
Ord Closure Source
Show Closure Source
Generic Closure Source
Pretty Closure Source
NFData Closure Source
Addresses Closure Source
type Rep Closure Source

newtype Heap Source

The heap stores closures addressed by memory location.

Constructors

Heap (Map MemAddr HeapObject)

Instances

Eq Heap Source
Ord Heap Source
Show Heap Source
Generic Heap Source
Pretty Heap Source
Monoid Heap Source
NFData Heap Source
type Rep Heap Source

data HeapObject Source

Constructors

HClosure Closure

Blackhole Integer

When an updatable closure is entered, it is overwritten by a black hole. This has two main benefits:

Memory mentioned only in the closure is now ready to be collected, avoiding certain space leaks.
Entering a black hole means a thunk depends on itself, allowing the interpreter to catch some non-terminating computations with a useful error

To make the black hole a bit more transparent, it is tagged with the STG tick in which it was introduced. This tag is used only for display purposes.

State information

data Info Source

User-facing information about the current state of the STG.

Constructors

Info InfoShort [InfoDetail]

Instances

Eq Info Source
Ord Info Source
Show Info Source
Generic Info Source
Pretty Info Source
NFData Info Source
type Rep Info Source

data InfoShort Source

Short machine status info. This field may be used programmatically, in particular it tells the stepper whether the machine has halted.

Constructors

NoRulesApply	There is no valid state transition to continue with.
MaxStepsExceeded	The machine did not halt within a number of steps. Used by `evalUntil`.
HaltedByPredicate	The machine halted because a user-specified halting predicate held.
StateError StateError	The machine halted in a state that is known to be invalid, there is no valid state transition to continue with. An example of this would be a `ReturnCon` state with an empty return stack.
StateTransition StateTransition	Description of the state transition that lead to the current state.
StateInitial	Used to mark the initial state of the machine.
GarbageCollection	A garbage collection step, in which no ordinary evaluation is done.

Instances

Eq InfoShort Source
Ord InfoShort Source
Show InfoShort Source
Generic InfoShort Source
Pretty InfoShort Source
NFData InfoShort Source
type Rep InfoShort Source

newtype NotInScope Source

Type safety wrapper.

Constructors

NotInScope [Var]

Eq StackFrame Source
Ord StackFrame Source
Show StackFrame Source
Generic StackFrame Source
Pretty StackFrame Source
NFData StackFrame Source
UpdateAddrs StackFrame Source
Addresses StackFrame Source
type Rep StackFrame Source

Bounded MemAddr Source
Enum MemAddr Source
Eq MemAddr Source
Ord MemAddr Source
Show MemAddr Source
Generic MemAddr Source
Pretty MemAddr Source
NFData MemAddr Source
UpdateAddrs MemAddr Source
Addresses MemAddr Source
type Rep MemAddr Source

Eq Globals Source
Ord Globals Source
Show Globals Source
Generic Globals Source
Pretty Globals Source
Monoid Globals Source
NFData Globals Source
UpdateAddrs Globals Source
Addresses Globals Source
type Rep Globals Source

Eq Locals Source
Ord Locals Source
Show Locals Source
Generic Locals Source
Pretty Locals Source
Monoid Locals Source
NFData Locals Source
UpdateAddrs Locals Source
Addresses Locals Source
type Rep Locals Source

Eq HeapObject Source
Ord HeapObject Source
Show HeapObject Source
Generic HeapObject Source
Pretty HeapObject Source
NFData HeapObject Source
Addresses HeapObject Source
type Rep HeapObject Source

Detail_FunctionApplication Var [Atom]
Detail_UnusedLocalVariables [Var] Locals
Detail_EnterNonUpdatable MemAddr [Mapping Var Value]
Detail_EvalLet [Var] [MemAddr]
Detail_EvalCase
Detail_ReturnCon_Match Constr [Var]
Detail_ReturnConDefBound Var MemAddr
Detail_ReturnIntDefBound Var Integer
Detail_EnterUpdatable MemAddr
Detail_ConUpdate Constr MemAddr
Detail_PapUpdate MemAddr
Detail_ReturnIntCannotUpdate
Detail_StackNotEmpty
Detail_GarbageCollected Text (Set MemAddr) (Map MemAddr MemAddr)
Detail_EnterBlackHole MemAddr Integer
Detail_UpdateClosureWithPrimitive
Detail_BadConArity

Eq InfoDetail Source
Ord InfoDetail Source
Show InfoDetail Source
Generic InfoDetail Source
Pretty InfoDetail Source
NFData InfoDetail Source
type Rep InfoDetail Source

Enter_NonUpdatableClosure
Enter_PartiallyAppliedUpdate
Enter_UpdatableClosure
Eval_AppC
Eval_AppP
Eval_Case
Eval_Case_Primop_Normal
Eval_Case_Primop_DefaultBound
Eval_FunctionApplication
Eval_Let Rec
Eval_Lit
Eval_LitApp
ReturnCon_DefBound
ReturnCon_DefUnbound
ReturnCon_Match
ReturnCon_Update
ReturnInt_DefBound
ReturnInt_DefUnbound
ReturnInt_Match

Eq StateTransition Source
Ord StateTransition Source
Show StateTransition Source
Generic StateTransition Source
Pretty StateTransition Source
NFData StateTransition Source
type Rep StateTransition Source

VariablesNotInScope NotInScope
UpdatableClosureWithArgs
ReturnIntWithEmptyReturnStack
AlgReturnToPrimAlts
PrimReturnToAlgAlts
InitialStateCreationFailed
EnterBlackhole
UpdateClosureWithPrimitive
NonAlgPrimScrutinee
DivisionByZero
BadConArity Int Int

Eq StateError Source
Ord StateError Source
Show StateError Source
Generic StateError Source
Pretty StateError Source
NFData StateError Source
type Rep StateError Source

Eq NotInScope Source
Ord NotInScope Source
Show NotInScope Source
Generic NotInScope Source
Pretty NotInScope Source
Monoid NotInScope Source
NFData NotInScope Source
type Rep NotInScope Source