For that matter, I actually have invented an entirely new programming language mostly with just Racket macros. It's an incredibly powerful tool for experimentation and research as well, something the PLT folks have been using to their advantage for some time now.
I'm currently in the guts of several different candidates for building a basic Lisp on Risc OS, and it's really struck home just how much of a lowering of the barriers a really first-class metaprogramming system is when it comes to language development.
Building everything from scratch takes time and often, a lot of repeat effort on stuff that's already been written a dozen times before. Macro systems, especially weapons-grade full-blown language development kits like what Racket can do, are a pretty hard thing to argue with on that front.
Dick Gabriel said in a podcast that late 70s language research was mostly lisp with macros. And when the PhD student was close to the finish line, he'd wrote a concrete syntax so it looked like a real-er thing.
I'm currently in the guts of several different candidates for building a basic Lisp on Risc OS, and it's really struck home just how much of a lowering of the barriers a really first-class metaprogramming system is when it comes to language development.
Building everything from scratch takes time and often, a lot of repeat effort on stuff that's already been written a dozen times before. Macro systems, especially weapons-grade full-blown language development kits like what Racket can do, are a pretty hard thing to argue with on that front.