> >If the databases *do* change over time, then there are two
> >possibilities:
> >
> > 1. the contents change due to external factors only
> > 2. the contents change because this program doing the writing
> >
> >in (1), you can still pretend the interface is pure, by
> imagining that
> >all the changes happened earlier. This works as long as you
> only read
> >the external data once.
>
> Isn't there the possibility of inlining causing a read to
> happen twice even if it only appears to happen once?
In theory that would be a valid transformation, but in practice no
compiler would duplicate arbitrary computations. GHC certainly doesn't.
Cheers,
Simon
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