Something has been eating at me for a while. There is a fundamental inconsistency in Python, something that has kept me from writing code how I'd like to write it, but I haven't been able to put my finger on it.

I think I finally have.When I first saw anonymous code blocks in Ruby, I thought "aha, that's it", and I was close. But really anonymous blocks aren't it. They just remind me of it. In fact they are a special case of "it". "It" happens to be expressions. Python makes a distinction between statements and expressions and because my background has been with procedural languages (Pascal, C), this distinction seemed natural. But Python's flexibility hints at something more, something that it has not quite provided but I couldn't describe. I liked the presence of functional tools in Python (map, filter, reduce, list comprehensions, etc), but bemoaned lambda's crippled self. I wanted a ternary operator. I've finally realized these things are all just ways of using statements as expressions, and I've also realized that statements really could be expressions, except that they are intentionally crippled in Python.

As anyone who reads this blog knows, I've been doing lots of work with Stan. Stan is an s-expression style DSL for generating XHTML from Python. I decided early on when creating the TurboStan plugin for TurboGears that I would keep Stan templates as pure expressions, even though I realized this would reduce their power to some extent. My feeling was that too much code in the template was wrong. I still feel that way. However, I don't feel that way about my program itself. I feel the language I use should not restrict me in fundamental ways. Many problem domains lend themselves to a functional style of programming and not having language support for that idiom can be painful. I do acknowledge that functional programs can be more difficult to take in at first glance, but they also tend to be more elegant when properly applied. The same argument can be made about many other concepts, such as recursion. Until you are familiar with the concept, recursive code can be like looking into a hall of mirrors. That certainly isn't a reason to not support it in a language. I don't think anyone would take a language seriously that didn't support recursion. Or object-orientation, for that matter. So why does functional-style programming have such a bad rap with the Python devs?

I admire Phillip Eby's work and find his articles thoughtful, so I emailed him about it (he probably thinks I'm a stalker). Anyway he suggested that having statements as expressions leads to nested code and flat is better than nested. This may be true. However so does nested functions and classes. Further, just because something can be abused doesn't mean it's necessary to ban it from the language, especially if having it easily doubles the expressive power of the language itself. Many hacks that have been added to the Python syntax to support special cases of functional programming would no longer be necessary. The syntax itself would be more self-consistent. I certainly don't find Lisp to be an attractive language visually, but I do find the concept it embodies quite elegant and tempting.

In short, I think Python needs to dump the artificial distinction between statements and expressions.

In the meantime, Phillip was kind enough to point me to Logix, which is more or less exactly what I'm asking for. It even generates Python bytecode.

So provided I'm able to actually leverage Logix for use in my day-to-day work, it may be goodbye Python (sort of) and hello, Logix.