>> That's not a valid argument. It's not an argument, it's a description. That is, in fact, the way Ruby generally works. >> Q: Why does your OS allow any pro

>> That's not a valid argument. It's not an argument, it's a description. That is, in fact, the way Ruby generally works. >> Q: Why does your OS allow any program to write anywhere in memory?" That's not an accurate comparison. A user installing two programs cannot be expected to ensure that they play nicely together. A programmer can be expected to ensure that an application's code and libraries play nicely together - especially in a non-compiled language, where you always have the source code. Even more especially where you have a community that generally promotes the best libraries and the developers who make them. >> How do you want people to be able to be able to reproduce state and to reason about a program if f*cking CONSTANTS can be modified!? I'm not proposing a crazy new system; I'm describing a language that has been quite successful. In actual practice, I have never, ever had a bug that was caused by a constant being redefined. I've never accidentally redefined one, and if, hypothetically, I did, I would see a warning. It might seem like a problem, but it isn't.