Nested function: Difference between revisions

=={{header|Haskell}}==

<lang haskell>import Control.Monad.ST

import Data.STRef

makeList :: String -> String

makeList separator = concat $ runST $ do

counter <- newSTRef 1

let makeItem item = do

x <- readSTRef counter

let result = show x ++ separator ++ item ++ "\n"

modifySTRef counter (+ 1)

return result

mapM makeItem ["first", "second", "third"]

main :: IO ()

main = putStr $ makeList ". "</lang>