Without Microsoft, TypeScript would not exist.

I’m not sure you are aware, but TypeScript is not the first language to compile to JavaScript.

https://stackoverflow.com/questions/4414558/languages-that-interpret-down-to-javascript
https://github.com/jashkenas/coffeescript/wiki/List-of-languages-that-compile-to-JS

Without TypeScript, people would have adopted a different JS transpiler, one that isn’t controlled by a monopolistic corporation with a history of extinguishing open source projects.

it would be great if they measured the results of opt1_idiomatic with _ => unreachable!(). In theory the compiler would optimize that better than _ => 0.

Oh great. A new flavour of regex, but it’s less portable and more verbose. https://xkcd.com/927/