pvar

Mutable variable with primitive values

BSD-3-Clause licensed by Alexey Kuleshevich

Maintained by [email protected]

This version can be pinned in stack with:pvar-0.1.1.0@sha256:4715f603c0e87dbccdd49e1958554f8771f7730c8a61561552690b929223aa8f,1798

Depends on 3 packages(full list with versions):

Interface for a mutable veriable PVar that can hold values that have Prim instance.

Status

Language	Travis	Azure	Coveralls

Package	Hackage	Nightly	LTS
`pvar`

Main features include:

Perfomance. There is practically no overhead when compared to operating on pure values, although there is a higher memory overhead, since PVar is backed by a MutableByteArray#
Atomic operations for PVars with Int values. This includes a unique function that is not availiable in ghc-prim out of the box:

atomicModifyIntPVar :: PrimMonad m => PVar m Int -> (Int -> (Int, a)) -> m a

Works in PrimMonad, therfore usable with ST, IO and various transformer monads.
Easy access to PVar contents with Storable
isByteArrayPinned, isMutableByteArrayPinned function that work on ghc-7.10 and ghc-8.0 as well as all the newer ones.

Addition of backwards compatible:
- isByteArrayPinned, isMutableByteArrayPinned (that work on ghc-7.10 and ghc-8.0)
- Primitive versions isByteArrayPinned#, isMutableByteArrayPinned#
Support for GHC 7.10 and GHC 8.0
Re-export sizeOf and alignment for easier compatibility with older primitive versions.