Look, I love functional programming. I use it all the time and I procrastinate in the shower about the best to add currying to all my favorite languages. That being said, even after all those years, I still find this:

    expr, res = "28+32+++32++39", 0
    for t in expr.split("+"):
        if t != "":
            res += int(t)
    
    print res 

SO MUCH more readable than this:

    from operator import add
    expr = "28+32+++32++39"
    print reduce(add, map(int, filter(bool, expr.split("+"))))

A couple years ago I created a library called Moka in python to make functional and nesting easier. That would be written this way:

    (Moka(expr)
       .do(string.split, '+')
       .keep(lambda x: x != "")
       .map(int)
       .reduce(moka.add))

Still, the imperative version, althought it has state and feels hacky for a functional hacker, is still pretty damn clear and easy to read.