Std.Data.PrimSTRef

This module provide fast unboxed references for ST monad. Unboxed reference is implemented using single cell MutableByteArray s to eliminate indirection overhead which MutVar# s a carry, on the otherhand unboxed reference only support limited type(instances of Prim class).

Unboxed ST references

data PrimSTRef s a

A mutable variable in the ST monad which can hold an instance of Prim.

newPrimSTRef :: Prim a => a -> ST s (PrimSTRef s a)

Build a new PrimSTRef

readPrimSTRef :: Prim a => PrimSTRef s a -> ST s a

Read the value of an PrimSTRef

writePrimSTRef :: Prim a => PrimSTRef s a -> a -> ST s ()

Write a new value into an PrimSTRef

modifyPrimSTRef :: Prim a => PrimSTRef s a -> (a -> a) -> ST s ()

Mutate the contents of an PrimSTRef.

Unboxed reference is always strict on the value it hold.