Copyright	(C) 2015 Edward Kmett
License	BSD-style (see the file LICENSE)
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	non-portable
Safe Haskell	Unsafe
Language	Haskell2010

Data.Struct.Internal

Contents

Tony Hoare's billion dollar mistake
Faking SmallMutableArrayArray#s
Field Accessors
Modifiers

Description

Synopsis

Documentation

data NullPointerException Source

Constructors

NullPointerException

Instances

Show NullPointerException Source
Exception NullPointerException Source

data Dict p where Source

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 Source

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

class Struct t where Source

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)) Source

Instances

Struct Object Source
Struct Label Source
Struct (LinkCut a) Source
Struct (Order a) Source

data Object s Source

Constructors

Object
Fields runObject :: SmallMutableArray# s Any

Instances

Struct Object Source
Eq (Object s) Source

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

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

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

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

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

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

pattern Struct :: () => Struct t => SmallMutableArray# s (Any *) -> t s Source

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

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

Tony Hoare's billion dollar mistake

data Box Source

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 Source

Constructors

Null

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

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 Source

Truly imperative.

Faking SmallMutableArrayArray#s

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

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

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

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

Field Accessors

data Slot x y Source

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)

Instances

Precomposable k k (Slot k k) Source

class Precomposable t where Source

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

Methods

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

Instances

Precomposable k * (Field k) Source
Precomposable k k (Slot k k) Source

slot Source

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)) Source

Get the value from a Slot

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

Set the value of a Slot

data Field x a Source

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 k * (Field k) Source

field Source

Arguments

:: Int	slot
-> Field s a

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

unboxedField Source

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 Source

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 Source

Get the value of a field in a struct

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

Set the value of a field in a struct

Modifiers

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

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