opt out of accursedUnutterablePerformIO

[Ben Franksen]

Am 05.03.2018 um 06:07 schrieb John Wiegley:
>>>>>> "DF" == David Feuer <david.feuer at gmail.com> writes:
> 
> DF> For the record, the "public" version of runRW# is called
> DF> unsafeDupablePerformIO. It would be a good idea to find out if it can
> DF> be used throughout bytestring without a significant penalty. If so,
> DF> that would eliminate a bunch of scary stuff. If not, it would be nice
> DF> to understand why.
> 
> In my tests, using unsafeDupablePerformIO instead of
> accursedUnutterablePerformIO induces a 15% performance penalty.

Thanks. I believe there are cases where people (other than me) would
like to have the option of sacrificing 15% performance to get rid of
aUPerformIO, if only for testing/bug-hunting purposes.

Cheers
Ben