atomic-primops

A safe approach to CAS and other atomic ops in Haskell.

After GHC 7.4 a new casMutVar# primop became available, but it's difficult to use safely, because pointer equality is a highly unstable property in Haskell. This library provides a safer method based on the concept of Tickets.

Also, this library uses the "foreign primop" capability of GHC to add access to other variants that may be of interest, specifically, compare and swap inside an array.

Note that as of GHC 7.8, the relevant primops have been included in GHC itself. This library is engineered to work pre- and post-GHC-7.8, while exposing the same interface.