After sharing the previous version here, I've received some valuable feedback, the main one being the weird unicode-based syntax throwing people off.
Prela now has a more familiar SQL-like syntax while adhering to the algebraic principle, which makes the language compositional and controllable, all the while keeping the core engine under 1k lines of code.
The engine has also been rewritten from Julia to Rust, resulting in both simpler code and faster performance (not just because "Rust fast Julia slow", but for some pretty deep compiler-level reasons that I'll hopefully write about at some point).
In the long run, I think the value of Prela is not as a single query language, but as a demonstration of the power of relation combinators which can be implemented in any language, just like iterators.