Re: The Revenge of Finalizers

Alastair:

...

I don't know how to achieve the same goal with atomicModifyIORef.

George:

I do. To modify ioRef1 and ioRef2 "simultaneously", write

atomicModifyIORef ioRef1 (\ contents1 -> unsafePerformIO ioRef2 (\ contents2 -> blah blah))

The actual modification will take place when the result or contents of ioRef1 or ioRef2 get evaluated.

I must be missing something because this seems to be riddled with race conditions. In particular, if ioRef1 is updated by a lazy function, then the write to ioRef1 happens but the write to ioRef2 does not. -- Alastair