[lmm]

> IO is the State monad where the state is the entire universe.

Maybe in the early days, but that doesn't really describe how it works these days (in particular, async exceptions). In practice it's been used as a "sin bin" type for any side effect that we don't know how to model nicely.

[codebje]

Are you referring to the argument that Haskell's IO type is insufficiently granular to distinguish between something like erasing a disk and something like catching an async exception, or that the language's first-class feature set should be extended to things like async exceptions so they don't need to be part of "the rest of the universe" ?

[lmm]

I'm saying that if you think of IO as being a state monad then you will be surprised by the behaviour of async exceptions (and likely introduce bugs in your program). I'm not taking a view on what Haskell should do, just saying that it's something people using the current IO type need to be aware of.