I've been struggling for the last few weeks to find a way to explain why I'm leaving Python. I could give the technical nitty-gritty (rejects functional programming, lacks lazy evaluation, grows syntactical features like cancer to overcome the first two design decisions), but at the end of the day, even with this intentional crippling of the language, it's still quite possible to write almost anything you want and actually be quite productive in Python.

So, in the face of this, what's my reason for leaving? Well, while it's possible to accomplish nearly any end result you like, you are constrained in how you get there. The language imposes an imperative style through its distinction between statements and expressions. The only way to achieve lazy evaluation is by using lambda and lambda is crippled by the presence of statements (which can't be used inside of a lambda).

Most Python fans claim (arguably with some validity) that these restrictions are in place to enforce code-readability.

Even if I grant that these restrictions do, in fact, help enforce a type of readability, I don't think anyone would disagree that it limits what a programmer is able to express. To me this argument is akin to demanding that authors limit themselves to 10th grade English so as to not confuse readers. While arguably effective, it also places a hard restriction on how concisely, elegantly, and accurately the writer can convey a concept. Worse, eventually the author will be crippled by this restriction as he or she will lose fluency in more esoteric corners of the language. His vocabulary will shrink from disuse.

In short, I think that such restrictions cater to the average (and below average) programmer. This is quite pragmatic, but hardly attractive if you want to advance your art. Poetry may be quite difficult to read at first, but is vastly rewarding once you've learned to appreciate it.