[IggleSniggle]

Just use a run-type transformer like typia, hooked right into typescript-compile. Get your runtime type validators generated from nothing but the typescript definitions.

Alternatively, use a runtime validator the provides good type inference out of the box so you're still only declaring your types once.

[JulianChastain]

I would recommend `zod` as a good typescript schema runtime validation library as well. It does require strict type checking to be on however.

[vendiddy]

I use zod but it's a workaround. I use non standard syntax to define types.

If typescript emitted type information, we'd be able to automatically get runtime validation at the boundaries of our apps.

[mixedCase]

Alternatively, io-ts is more performant and has been around for a while longer. Although it does have a more functional interface.

[IggleSniggle]

I like typia for doing codegen basically in the way this request is asking: it hooks into the typescript API to create runtypes from plain old typescript