Wow! This is cool stuff. I was looking through the documentation for conditional logic, control flow, IF(), and the CASE...WHEN...THEN operator. It seems like

Wow! This is cool stuff. I was looking through the documentation for conditional logic, control flow, IF(), and the CASE...WHEN...THEN operator. It seems like the ternary operator is the single way to implement conditionality? At https://prql-lang.org/book/examples/functions.html https://prql-lang.org/book/examples/functions.html I found the example `func if_valid x`, which is then used in the `derive` expression `prices_adj | ret | if_valid`. This usage of `if_valid` at the end of the pipeline seems a bit awkward: if I want to do the whole calculation only if some condition is met, I'd like to write it at the front of the pipeline. Can I nest the `ret` function in the if-function like so?: `func ret_if_valid x -> is_valid_price ? (ret x) : null` Then I guess I'd have to do: return_total = prices_adj | ret_if_valid Next, can a string variable be used as part of a column name? It's something I needed recently in order to categorise values and use them to do a pivot. For example, I had to do: SELECT CASE category WHEN 'a' THEN 'x' AS newCategory ... SELECT SUM( if(newCategory = 'a', revenue, 0) ) AS aRevenue, ... Ideally I'd like to do: aggregate [ for x in ['a', 'b', 'c']: (concat x 'Revenue') = sum ( [new_category == x] ? revenue : 0 ), ...] i.e. I'd like to use x as part of the final column name. A pivot example would be great (or maybe you already have a PIVOT implementation in mind). I'd be interested in contributing to this, guess I'll take a look at the code and any community chat you've set up!