Data.Struct.Internal

Documentation

>>> import Control.Monad.Primitive

data NullPointerException

Constructors

NullPointerException

Instances

Show NullPointerException

Defined in Data.Struct.Internal

Methods

showsPrec :: Int -> NullPointerException -> ShowS

show :: NullPointerException -> String

showList :: [NullPointerException] -> ShowS

Exception NullPointerException

Defined in Data.Struct.Internal

Methods

toException :: NullPointerException -> SomeException

fromException :: SomeException -> Maybe NullPointerException

displayException :: NullPointerException -> String

data Dict p where

A Dict reifies an instance of the constraint p into a value.

Constructors

Dict :: p => Dict p

st :: PrimMonad m => ST (PrimState m) a -> m a

Run an ST calculation inside of a PrimMonad. This lets us avoid dispatching everything through the PrimMonad dictionary.

class Struct t where

An instance for Struct t is a witness to the machine-level equivalence of t and Object.

Minimal complete definition

Nothing

Methods

struct :: Dict (Coercible (t s) (Object s))

struct :: Coercible (t s) (Object s) => Dict (Coercible (t s) (Object s))

Instances

Struct Object

Defined in Data.Struct.Internal

Methods

struct :: Dict (Coercible (Object s) (Object s))

Struct Label

Defined in Data.Struct.Internal.Label

Methods

struct :: Dict (Coercible (Label s) (Object s))

Struct (LinkCut a)

Defined in Data.Struct.Internal.LinkCut

Methods

struct :: Dict (Coercible (LinkCut a s) (Object s))

Struct (Order a)

Defined in Data.Struct.Internal.Order

Methods

struct :: Dict (Coercible (Order a s) (Object s))

data Object s

Constructors

Object

Fields

• runObject :: SmallMutableArray# s Any

Instances

Struct Object

Defined in Data.Struct.Internal

Methods

struct :: Dict (Coercible (Object s) (Object s))

Eq (Object s)

Defined in Data.Struct.Internal

Methods

(==) :: Object s -> Object s -> Bool

(/=) :: Object s -> Object s -> Bool

coerceF :: Dict (Coercible a b) -> a -> b

coerceB :: Dict (Coercible a b) -> b -> a

destruct :: Struct t => t s -> SmallMutableArray# s Any

construct :: Struct t => SmallMutableArray# s Any -> t s

unsafeCoerceStruct :: (Struct x, Struct y) => x s -> y s

eqStruct :: Struct t => t s -> t s -> Bool

pattern Struct :: Struct t => SmallMutableArray# s Any -> t s

alloc :: (PrimMonad m, Struct t) => Int -> m (t (PrimState m))

Allocate a structure made out of n slots. Initialize the structure before proceeding!

Tony Hoare's billion dollar mistake

data Box

Box is designed to mirror object's single field but using the Null type instead of a mutable array. This hack relies on GHC reusing the same Null data constructor for all occurrences. Box's field must not be strict to prevent the compiler from making assumptions about its contents.

Constructors

Box Null

data Null

Constructors

Null

isNil :: Struct t => t s -> Bool

Predicate to check if a struct is Nil.

>>> isNil (Nil :: Object (PrimState IO))
True
>>> o <- alloc 1 :: IO (Object (PrimState IO))
>>> isNil o
False

pattern Nil :: Struct t => t s

Truly imperative.

Faking SmallMutableArrayArray#s

writeSmallMutableArraySmallArray# :: SmallMutableArray# s Any -> Int# -> SmallMutableArray# s Any -> State# s -> State# s

readSmallMutableArraySmallArray# :: SmallMutableArray# s Any -> Int# -> State# s -> (#State# s, SmallMutableArray# s Any#)

writeMutableByteArraySmallArray# :: SmallMutableArray# s Any -> Int# -> MutableByteArray# s -> State# s -> State# s

readMutableByteArraySmallArray# :: SmallMutableArray# s Any -> Int# -> State# s -> (#State# s, MutableByteArray# s#)

casSmallMutableArraySmallArray# :: SmallMutableArray# s Any -> Int# -> SmallMutableArray# s Any -> SmallMutableArray# s Any -> State# s -> (#State# s, Int#, SmallMutableArray# s Any#)

Field Accessors

data Slot x y

A Slot is a reference to another unboxed mutable object.

Constructors

Slot (forall s. SmallMutableArray# s Any -> State# s -> (#State# s, SmallMutableArray# s Any#)) (forall s. SmallMutableArray# s Any -> SmallMutableArray# s Any -> State# s -> State# s) (forall s. SmallMutableArray# s Any -> SmallMutableArray# s Any -> SmallMutableArray# s Any -> State# s -> (#State# s, Int#, SmallMutableArray# s Any#))

Instances

Precomposable (Slot :: k1 -> k2 -> Type)

Defined in Data.Struct.Internal

Methods

(#) :: Slot x y -> Slot y z -> Slot x z

class Precomposable t where

We can compose slots to get a nested slot or field accessor

Methods

(#) :: Slot x y -> t y z -> t x z

Instances

Precomposable (Slot :: k1 -> k2 -> Type)

Defined in Data.Struct.Internal

Methods

(#) :: Slot x y -> Slot y z -> Slot x z

Precomposable (Field :: k -> Type -> Type)

Defined in Data.Struct.Internal

Methods

(#) :: Slot x y -> Field y z -> Field x z

slot

Arguments

:: Int

slot

-> Slot s t

The Slot at the given position in a Struct

get :: (PrimMonad m, Struct x, Struct y) => Slot x y -> x (PrimState m) -> m (y (PrimState m))

Get the value from a Slot

set :: (PrimMonad m, Struct x, Struct y) => Slot x y -> x (PrimState m) -> y (PrimState m) -> m ()

Set the value of a Slot

cas :: (PrimMonad m, Struct x, Struct y) => Slot x y -> x (PrimState m) -> y (PrimState m) -> y (PrimState m) -> m (Bool, y (PrimState m))

Compare-and-swap the value of the slot. Takes the expected old value, the new value and returns if it succeeded and the value found.

data Field x a

A Field is a reference from a struct to a normal Haskell data type.

Constructors

Field (forall s. SmallMutableArray# s Any -> State# s -> (#State# s, a#)) (forall s. SmallMutableArray# s Any -> a -> State# s -> State# s)

Instances

Precomposable (Field :: k -> Type -> Type)

Defined in Data.Struct.Internal

Methods

(#) :: Slot x y -> Field y z -> Field x z

field

Arguments

:: Int

slot

-> Field s a

Store the reference to the Haskell data type in a normal field

unboxedField

Arguments

:: Prim a

=> Int

slot

-> Int

argument

-> Field s a

Store the reference in the nth slot in the nth argument, treated as a MutableByteArray

initializeUnboxedField

Arguments

:: (PrimMonad m, Struct x)

=> Int

slot

-> Int

elements

-> Int

element size

-> x (PrimState m)

struct

-> m (MutableByteArray (PrimState m))

Initialized the mutable array used by unboxedField. Returns the array after storing it in the struct to help with initialization.

getField :: (PrimMonad m, Struct x) => Field x a -> x (PrimState m) -> m a

Get the value of a field in a struct

setField :: (PrimMonad m, Struct x) => Field x a -> x (PrimState m) -> a -> m ()

Set the value of a field in a struct

Modifiers

modifyField :: (Struct x, PrimMonad m) => Field x a -> x (PrimState m) -> (a -> a) -> m ()

modifyField' :: (Struct x, PrimMonad m) => Field x a -> x (PrimState m) -> (a -> a) -> m ()