I'm honestly curious. What other languages have a type system the would allow for this project? That is, (a subset of) SQL as a type. And assuming these languages exist, are they as ergonomic to the developer as TS while instrumenting the above?
Same thing but actually readable and maintanable would've been better implemented as a compile-time (build-time) script, basically source code generation.
Source code generation wouldn't really provide the same end-user ergonomics and, frankly, would barely resemble the same project. How would that work? You generate source code from a SQL string and a data source? At that point you might as well just... write the actual code. The point of this package is that type information is dynamically assigned according to arbitrary "SQL" queries at compile-time[0].
Have you gone through short exercise I outlined below? Surely you can't think it would be better to manually generate type information than have it automagically available and enforced instantly as you work?
The closest thing I've seen to this is "type providers" in F#. Where, given a database connection, a "Provider" can offer compile-time contracts between your code and the schema of the database. What it does not do is provide contracts against arbitrary projections of the database (SQL queries). Of course one can write code that queries and transforms the data in a type-safe way, but these "transformations" must happen in F# for the compiler to infer any new types.
This project takes the above to a different level and infers the type of the result of an arbitrary (subset of) SQL operation before it is ever executed. It's fairly impressive.
[0] This has been pointed out more than once already, but this project does offer compile-time guarantees
type EX = Query<"some query string", db>;
For example, add this below `EX1` (line 66) in the TS Playground:
let names = (persons: EX1) => persons.map(person => person.name);