Re: [Haskell-cafe] MVar which can not be null ?

If you have only one variable then you can use: atomicModifyIORef from IORef it will give you atomic transactions and IORef will always contains some value. If you have a list of variables you need to make atomic actions on, then you may like to use STM. On 18 March 2013 11:07, s9gf4ult <s9gf4ult@gmail.com> wrote:

Hello, I am looking for MVar which can not be null. I need some kind of thread save atomic IO operation like I can do with modifyMVar, but I want this variable always contain some value and never be null. Thanks.

-- Alexander