In Haskell, to define a function that returns a function similar to the SML-like syntax, you can use lambda expressions. The example provided illustrates this with the function `foo`, which takes an argument and returns a function that increments its input by one. The concise version of this function can be expressed as `foo = const (+1)`. Additionally, there is a request for a Haskell function that removes consecutive duplicate characters from a string, such as transforming "abaacccdee" into "abacde". This requires implementing a function that processes the string and filters out adjacent duplicates.
