Data.Primitive.PrimVar

PrimVar is internally a PrimArray of one element, but with a convenient MutVar-like API.

Types

newtype PrimVar s a

Constructors

PrimVar (MutablePrimArray s a)

Allocation

newPrimVar :: (Prim a, PrimMonad m) => a -> m (PrimVar (PrimState m) a)

Create a new PrimVar with the specified initial value.

newPinnedPrimVar :: (Prim a, PrimMonad m) => a -> m (PrimVar (PrimState m) a)

Create a new pinned PrimVar with the specified initial value. The garbage collector is guaranteed not to move it.

newAlignedPinnedPrimVar :: (Prim a, PrimMonad m) => a -> m (PrimVar (PrimState m) a)

Create a new pinned PrimVar with the specified initial value and with the alignment given by its Prim instance. The garbage collector is guaranteed not to move it.

Access

readPrimVar :: (Prim a, PrimMonad m) => PrimVar (PrimState m) a -> m a

Read the value of a PrimVar.

writePrimVar :: (Prim a, PrimMonad m) => PrimVar (PrimState m) a -> a -> m ()

Write a new value into a PrimVar.

modifyPrimVar :: (Prim a, PrimMonad m) => PrimVar (PrimState m) a -> (a -> a) -> m ()

Mutate the contents of a PrimVar.

Information

samePrimVar :: PrimVar s a -> PrimVar s a -> Bool

Check if two PrimVars refer to the same memory block.

primVarContents :: PrimVar s a -> Ptr a

Yield a pointer to a PrimVar's data. This operation is only safe on pinned PrimVars allocated by newPinnedPrimVar or newAlignedPinnedPrimVar.

isPrimVarPinned :: PrimVar s a -> Bool

Check whether or not a PrimVar is pinned.