runSTArray for multiple arrays

[Henning Thielemann]

Currently, runSTArray can handle only one array:

runSTArray :: Ix i => (forall s . ST s (STArray s i e)) -> Array i e


Would it be possible to access multiple arrays successively by a function 
like

runSTArraySplit :: Ix i =>
    (forall s . ST s (STArray s i e, a)) ->
    (Array i e, ST t a)

Hm, this would not work, because type variables 's' in 'a' had to be 
converted to 't' as well. Are there other ideas to tackle this problem?