On Sat, 25 Oct 2008, Paul L wrote:
I'm have some trouble using the ST monad, and I think
I'm confused about its use of existential type.
{-# OPTIONS -XRankNTypes #-}
import Control.Monad.ST
import Data.Array.ST
I want to implement a map function that unfold
all ST monads in a list:
mapST :: (a -> (forall s . ST s b)) -> [a] -> [b]
mapST f (x:xs) = runST (f x) : mapST f xs
mapST f [] = []
I think mapM with subsequent runST should work.
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