https://typing.io/ This is pretty similar I think, used in the past. Can use your own code with the paying/subscription

Hello -- I'm glad you like it! I believe typing.io has something like this, but for programming languages.

Or to improve your code writing speed and syntax familiarity; it would have to be integrated into your editor/IDE and tooling though, since I find that in some cases it helps a bit with productivity (autocomplete, auto-close, auto-format, etc).

https://en.wikipedia.org/wiki/Compute!

(It says they quit doing the type-in programs after 1988)

That’s exactly how I learned to code. Retyping code from Byte magazine, Dr. Dobbs, and Apple Incider.

Also works for human languages!

yes, instead of learning dart, you will be tasked with writing microsoft excel in dart