[dragonwriter]

The share of projects that start out “we’re going to do X, and conpletely support using the syntax and semantics of existing language Y, but add more on top” that end up “we’re going to do X, in a language vaguely reminiscent of Y” is very hard to distinguish from 100%.

[fulafel]

I guess there's survivorship bias, but the ones that first come to mind fared pretty well with compatibility (eg C++, Typescript, Ocaml)