I don't think I put it very well the first time, so let me try again. Racket, the platform, is very unlike common programming languages like Python, Ruby, Perl

I don't think I put it very well the first time, so let me try again. Racket, the platform, is very unlike common programming languages like Python, Ruby, Perl, JS, etc. And I don't mean the fact that it's a Scheme/Lisp. I mean the Language Oriented Programming [1] features it's built for. It is a platform for designing and building languages. It's only sensible that it should be able to run all the different languages in the same program. In fact, one can create an arbitrary new language and use that new language all within the same running process. In fact, as you can see from the link I cite in [1], the languages can all look and behave completely differently, and yet all be valid "Racket": put them in a .rkt file and load it up and see. I can now sort of understand your view. I am not a Racket contributor, though I do use it every now and then, and to me "building a new language in Racket" now means something completely different than what it'd have meant before I became familiar with Racket (the platform). I think the difference stems from the fact that what Racket calls a "language" (`#lang`, in Racket terms), is actually just a syntax. In languages like Python/Perl/JS, the syntax and the semantics are so closely intertwined they might as well be the same thing, and we call this "single" thing "the language". But neither of those syntaxes are as extensible/user-modifiable as in a lisp, and none of those semantics are available for use with different syntaxes as in Racket. A "language" in Racket does not change the core semantics of Racket-the-platform, only the syntax available to the programmer in that one file/module, and how that syntax gets translated into core Racket semantics. In this way, `#lang pollen` and `#lang bf` are not any special "compatibility modes" of Racket. In fact, right now, there exist multiple "Racket"s within Racket: there's `#lang racket/base` and `#lang racket` and then there's the type-checking variant `#lang typed/racket`. Neither is a special mode of another, or of the runtime; all are just different syntaxes of the same runtime. I reckon Racket 2 will similarly be just a different syntax. Or, as we like to call those in Racket terms: a `#lang`-uage. 1: https://beautifulracket.com/appendix/why-lop-why-racket.html https://beautifulracket.com/appendix/why-lop-why-racket.html