I like the first lesson (http://bartoszmilewski.com/2014/11/04/category-the-essence-of-composition/ http://bartoszmilewski.com/2014/11/04/category-the-essence-o

I like the first lesson (http://bartoszmilewski.com/2014/11/04/category-the-essence-of-composition/ http://bartoszmilewski.com/2014/11/04/category-the-essence-o...). There are some neat challenge problems. It turns out Python does an excellent job of dealing with them: > Implement, as best as you can, the identity function in your favorite language (or the second favorite, if your favorite language happens to be Haskell). def identity(x): return x > Implement the composition function in your favorite language. It takes two functions as arguments and returns a function that is their composition. def compose(f, g): return lambda *args, **kwargs: f(g(*args, **kwargs)) Testing these out: >>> compose(lambda x: x+1, lambda y: y-1)(0) 0 >>> compose(identity, identity)(0) 0