Function parsing with pipe

[broneill]

I'm experimenting with the parser, and something is confusing me.

let a = 3 | math.pow 2 # illegal -- unexpected | while parsing function call
let a = (3 | math.pow 2) # legal

I don't understand why parens are needed in order for the expression to be parsed. In other contexts, the parens aren't needed.

[max-sixty]

Yes, the rules around parentheses are some of my least favorite rules. Check out https://prql-lang.org/book/reference/syntax/operators.html#parentheses...

The reason we can't always loosely bind = so that let a = 3 | math.pow 2 parses to let a = & 3 | math.pow 2 is because that would parse join foo=bar (==id) to join foo= & bar (==id), which isn't right. If we had different syntax for aliases vs. assignments, then we could bind = in the first example tighter, and require fewer parentheses.

But this was the best tradeoff we could come up with. (Lots of old issues on this that are required context to make progress here...)

[broneill]

Perhaps the language grammar needs a complete review and possible overhaul? The version is at 0.11.4, still quite young.

[max-sixty]

This is a constraint of the current language. Check out #437 & links for past discussions. Starting to discuss a change would require examples, which take into account those past discussions...

[broneill]

I'm suggesting any specific changes, because I have no context. The review process is for the experts.