Hi, 


by trying to understand how "writeIORef" works, I looked at


<fontfamily><param>Courier</param><x-tad-bigger>data
</x-tad-bigger><color><param>0000,0000,A09F</param><x-tad-bigger>STRef</x-tad-bigger></color><x-tad-bigger>
s a =
</x-tad-bigger><color><param>0000,0000,E0DF</param><x-tad-bigger>STRef</x-tad-bigger></color><x-tad-bigger>
(MutVar# s a)


</x-tad-bigger></fontfamily> what is MutVar# ? (especially zhe "#" ) ?
I've readed tha writeIORef (and readIoRef etc) is used to write
directly to memory places fo implementing variables, as in example in
HOpenGL used.  Is this also Haskell standard ?


Thanks for help



Hans