JEXL / SelectVariants / Multi-allelic and filtering lists?

[bbimber]

Hello,

When using JEXL expressions, is there a good built-in solution for handling both single and multi-allelic sites? A good example is trying to filter on AF, which could be either a single number or a list. Perhaps I'm missing something now, but it seems like there are two possibilities:

1. Split multi-allelic sites into multiple variants (like VariantsToTable can do), and output/filter them independently.
2. Support functions, like perhaps min() and max(). One would need to think about the desired result, but filtering on "min(AF) < 0.05" might be reasonable. In the simplest implementation, the entire site would be in or out (as opposed to trying to be smart about filtering specific alt alleles).

Just curious if there is something built-in i'm missing, or if ways to support this have already been discussed.