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

Svein Ove Aas svein.ove at aas.no
Thu Mar 5 11:13:10 EST 2009

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
for an example.

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