Comment by jitl

I'm surprised that none of the examples on Github or the website deals with join. I eventually found some in the "book" here: https://prql-lang.org/book/transforms/join.html

    from employees
    join side:left positions [id==employee_id]

turns into

    SELECT
      employees.*,
      positions.*
    FROM
      employees
      LEFT JOIN positions ON id = employee_id

I would love to see joins worked into the main learning examples. Without join, the examples lack a bit of the "relation" part; we could just as easily be compiling a DSL to a chain of `array.filter`, `array.reduce`, `array.map` calls. Joins are what makes relational modeling interesting!

I would love to see Datalog/SPARQL-style implicit joins to make graph traversals like "which users have edited documents I own?" less verbose.