[untog]

This is quite difficult to make sense of beyond the initial description so I’m not sure about the current status. But it would be a shame to lose valuable type info because compile times are long... isn’t there a tool out there that does nothing except strip types from TS files? If you used that you could get quick rebuilds when developing but retain type checking when you do a full build.

EDIT: Sucrase! That’s what I was thinking of:

https://github.com/alangpierce/sucrase#transforms

[alangpierce]

Hi, Sucrase author here. I'm also having a hard time understanding the rationale here, but it looks like it's maybe a nuance around self-hosting. In general, for any regular TS project, I'd certainly recommend decoupling typecheck and transpile as separate operations and running typecheck alongside lint. IMO one of the nicest things about TypeScript is that you can run your code before you've figured out how to get the types to check out.

They do consider swc (which has roughly the game goal as Sucrase) in the conversation, so it seems like there's some consideration of a transpile-only approach. TypeScript's built-in `transpileModule` is probably the most reliable and officially-supported way to get the equivalent, and is much faster than running TSC with typechecking.