A couple patches

[Neil Mitchell]

Hi

> The unsafePerformIO patch is something Neil asked me to send in. It's a
> cleaned up, slightly renamed and documented version of inlinePerformIO
> that we use in ByteString, but exported from System.IO.Unsafe.
> Similarly, the unsafeDupablePerformIO are also exported (separate
> patches). And implementations are given for non-GHC so it should all
> still work. This is not a direct proposal, but rather a request for
> comments. If people think it's not insane to give people this much rope
> then we can send the patch through the libraries submission process.

As I requested it, its not entirely surprising that I support this.
The reality is that in some cases people need this rope (I do for
Uniplate and Supero, for instance) and I'd rather get my rope in a
properly documented portable manner, than getting black-market rope
which may disappear some day.

That said, my guess is that the unsafePerformIO patch should go
through the libraries submission process.

Thanks

Neil