Yes and no. The order IO is performed is well-defined (that's the purpose of the IO monad), but the evaluation order is not (apart from ordering arising from da

Yes and no. The order IO is performed is well-defined (that's the purpose of the IO monad), but the evaluation order is not (apart from ordering arising from data dependency), and this is the case with or without unsafePerformIO. You just won't get any different behaviour with safe Haskell code, and Haskell is very much on the safe side of things, so even though the order of evaluation may be indeterminate, you would never notice it (maybe a timing attack is possible?). But this is admittedly hair-splitting.