RealWorld

[Alastair Reid]

> This constrains the implementations of IORef and STRef to be the same
> (obviously).  I can't immediately see any benefit from using different
> implementations for these two types, so maybe it's not an issue.

I could be a bit out of date but I think Hugs uses different implementations 
because IO has concurrency and exceptions and ST doesn't.  Apart from effort 
required, I don't know if there is any cost in switching.

--
Alastair