On 29 April 2004 10:17, David Sabel wrote:
You could try out that theory by copying the definition of unsafePerformIO into your code, and putting an INLINE pragma on it. I think it's safe to do this in your case (it's not safe in general).
That's interesting for me, in which situations isn't it safe to inline the definition of unsafePerformIO?
We try to maintain the invariant that the IO action that is the argument to unsafePerformIO is atomic, in the sense that it is either completely performed or not performed when the application of unsafePerformIO is evaluated (ignoring exceptions). If we let the compiler inline unsafePerformIO, then the compiler would sometimes be able to share part of the IO computation amongst multiple instances, because it can see that the first action is applied to the realWorld# constant. Cheers, Simon