Lots of comments here about similar projects in a different language, but the fact that this targets TypeScript is explicitly what makes it interesting to me. Using regular Javascript database libraries, even ones that have type definitions, require a lot of double typing.
I've been relatively satisfied with TypeORM, but one thing that's been a hurdle for me to some extent is its reliance on experimental decorators, and the resulting incompatibility with Babel - which in turn makes it harder to integrate with the wider ecosystem, e.g. Next.js.
As far as I can see on first glance, there's nothing here yet that makes it incompatible with Babel, so my tip would be to make it an explicit goal to keep it that way :)
Opening a can of worms for sure, but the reliance on Babel in the JS community is not a good thing to me. It's another reason why I prefer TypeScript, as in TSC, not whatever equivalent babel happens to support.
I do agree that sticking to TSC keeps things a lot simpler, and that should be the default setup.
Pandora's box has been opened though. Majority of the JS community seem to have adopted Babel in their workflow.
Even as I question it, I must admit it's pretty sweet to have a transpiler in the buid toolchain. It frees one from the browser/backward compatibility question, more or less, and opens up the language to be extensible - for better or worse.
For example, Babel macros ¹ is an interesting concept, using the language to extend the language during compile time.
To bring it back to the topic at hand (PgTyped, Typesafe SQL) - one thing that I'd like to see in TSC is a way to output type definitions (either inlined metadata or external JSON schema), to be consumed for run-time type checking. That would "complete the circle" for me.
TypeScript "compiler plugins" seem to be on the roadmap, or at least under consideration ². Some may see that as opening a proverbial can of worms, down a similar road to Babel. I wouldn't disagree, but it'd be so useful!
Opt-in runtime checks for SQL queries are also on the roadmap for PgTyped. You are welcome to open an issue to track our progress there if you think this feature will be useful for you.