[Haskell-cafe] Re: [Haskell] Lazy IO breaks purity

[Svein Ove Aas]

On Thu, Mar 5, 2009 at 2:08 PM, Simon Marlow <marlowsd at gmail.com> wrote:
>
> So the argument is something like: we can think of the result of a call to
> unsafeInterleaveIO as having been chosen at the time we called
> unsafeInterleaveIO, rather than when its result is actually evaluated. This
> is on dodgy ground, IMO: either you admit that the IO monad contains an
> Oracle, or you admit it can time-travel.   I don't believe in either of
> those things :-)
>
As it turns out, time-travel as a vehicle for computation has a long
tradition in the more advanced systems; see
http://www.frc.ri.cmu.edu/~hpm/project.archive/general.articles/1991/TempComp.html
for an example.