Re: Can strict ST break referential transparency?

So my theory is correct, but it is already fixed in 8.2. Nice! Thank you for clarification! Yuras. 23-11-2017, Чцв а 10:20 -0500, Ben Gamari напісаў:

Yuras Shumovich writes:

...

Hello,

Hello,

Sorry for the late reply; this required a bit of reflection. The invariants surrounding the suspension of ST computations is a rather delicate and poorly documented area.

I believe the asynchronous exception case which you point out is precisely #13615. The solution there was, as David suggests, ensure that no resulting thunk could be entered more than once by a very strict blackholing protocol. Note that this isn't normal "eager" blackholing protocol, which still might allow multiple entrancy. It's rather a more strict variant, requiring two atomic operations.

I can't be certain that there aren't more cases like this, but I suspect not since most asynchronous suspensions where the resulting thunk might "leak" back into the program go through the raiseAsync codepath that was fixed in #13615.

Cheers,

- ben