October 13th, 2009
This idea came to me as a tweet, but was way too long for a tweet. As it turns out, it’s also something I’ve been saying a lot lately, since it’s the answer to one of the very common arguments against dynamic languages.
The argument usually goes like this: “Dynamically typed languages are fine for smaller programs and simple web applications, but if you’re building something big, something that will be several millions of lines of code, you really need all the tools you can only get from a statically typed language”. Where the statically typed language mentioned is typically Java. The argument is still common enough without any specific language name mentioned though.
Interestingly, there are several problems and fallacies in this seemingly simple argument. I’m not going to tackle all of them here, but just focus on the beginning. Namely the idea that you are building something big. First of all, how do you know that? Have you done anything like it before? And how do you know it would be big in a different language? How do you know you can’t decouple the application in such a way you won’t have to build anything big? There are so many assumptions that can be questioned here. But at the end of the day, my glib answer that summarizes this usually goes something like this:
“Optimizing for your software project becoming big is the same as optimizing a car to hit a rock wall – you are optimizing for failure”
I firmly believe that becoming big is really failure. Once you have a big enough project you have lost. It might still work, but the cost will be extreme, and maintaining it will be a large burden too.
This is the reason I like agile. It emphasizes small, working pieces all the time. If you work with code this way, you can’t really become big. Instead, your project will be forced to be modularized and divided into smaller, more logical components that are highly cohesive and decoupled from each other.