[Haskell-cafe] Re: Fast Mutable Variables for the IO and ST monads

Simon Marlow wrote:

I suggest you follow the same scheme as the unboxed array types, and have IOURef/STURef types, parameterised over the element type. Of course, we should have instances for all of the primitive numeric types plus Ptr, ForeignPtr, StablePtr, Bool.

Perhaps it may be worth to introduce a class Unpackable as described at the end of http://www.haskell.org/pipermail/haskell-cafe/2004-July/006400.html so we may define STUArray as an instance of MArray, and other similar unpackable things easier?