Extra unsafe sequencing of IO actions from Twan van Laarhoven
packaged up, along with unfoldIO and an implementation of Scala's List Buffer. This means we can have tail
recursive sequence and traverse specialised for lists of IO actions.
For algorithms which are more easily written in a mutable way we have ListBuilder s a. A ListBuilder s a
is like a wrapper around an ST s [a], but with a constant time append as well as prepend.
Basic usage:
import qualified Data.ListBuilder as ListBuilder
palindrome :: [a] -> [a]
palindrome xs = runST $ do
bldr <- ListBuilder.newBuilder
for_ xs $ \x -> do
ListBuilder.prepend x bldr
ListBuilder.append x bldr
ListBuilder.unsafeFreeze bldrOther functions of interest:
traverseIO :: (a -> IO b) -> [a] -> IO [b]
sequenceIO :: [IO a] -> IO [a]
unfoldIO :: IO (Maybe a) -> IO [a]