But, why does it matter? It matters because writing tools for your language in another language tells me something. It tells me that:
- It's possibly harder to write in than Java
- It's hard to parse
- Limited or no reflection support
- Not user friendly
- Can not perform well enough to support tools written in itself
Any of the above points are bad in my book. But, I see it constantly in new programming languages (even in ones 10+ years old). Now, I love languages and learning them. Why? Because I always walk away with a new way of thinking about things. It's also nice to see how other people solve certain problems. It shocks me though that so many languages depend on Eclipse or Emacs for their tools. At some point, a language moves from command line pet project to a true programmer amplifier. The language has to be elegant in syntax, yet have the tools to make debugging and reasoning about the system simple.
Now, before you get angry with me, I do realize that using Emacs or Eclipse gives a huge boost in the beginning with their frameworks. But, by never leaving them, it could also mean there are holes in your frameworks or in your language itself. Tools written in your language help to expose issues like limited reflection or that your language is hard to parse. I believe writing tools should be easy and for everyone to do. If writing tools in your language is hard, then you might need to redesign your language.
I think if we had more languages that had their tools written in them, we would all benefit. Plus, with tools written in your language, new developers have some example code that has real world applications. The way to prove to me if your language is elegant is not to show me how easy factorial is to write, but to show me how easy it is to write an inspector.