Description: The well-known `reverse` with a helper function that accumulates the tail of the result. The helper function is written as an anonymous function (lambda). This way it might resemble JavaScript with its `this` or `self`. Since the helper function must be recursive, we use the higher-order `fix`. (Since I swapped the order of arguments of the helper compared to the usual one, we can't make it even shorter. See the next version)

Source code (Latest version): import Data.Function rvrs :: [a] -> [a] rvrs = fix (\self outTail inTail -> case inTail of [] -> outTail x:xs -> self (x:outTail) xs) [] main = rvrs "abc"