Factor: a practical stack language: - why I love following Factor development: the programmers have no qualms about radically redesigning the language and making massive changes to semantics, even shying away from redesigning defining words. This of course makes the use of the language for real purposes a bit hairy, but it's simply thrilling to see how language constructs are juggled and the path to an optimal language is sought. And since they adjust the entire included library every time, the transition pains are not quite as great (and the included library is already absolutely impressive and currently has one of the best Unicode implementations I've seen so far)