I wrote:
Am I missing something?
Yes! In reality, I do not need unsafeSTRef for this
at all, using a type suggested earlier by Udo:
stToState :: MonadState st m => (forall s. STRef s st -> ST s a) -> m a
stToState f = do
s <- get
let (y, s') = runST (stm f s)
put s'
return y
where
stm f s = do
r <- newSTRef s
y <- f r
s' <- readSTRef r
return (y, s')
This works! Thanks, Udo!
-Yitz
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