Simple haskell var passing example.

var_passing.hs

import System.IO

main :: IO ()
main = do
    val <- getLine            -- "val" here belongs to main's scope.
    putStrLn (myfun val)      -- pass the val to myfun, since it's out
                              -- of it's scope.

myfun :: String -> String
myfun a = "My value is " ++ a -- myfun knows nothing of 'val', as it
                              -- belongs to main's function scope