Function style: Prefer function, allow for arrow functions for closures

[mikkurogue]

My team uses Biome and we now manually enforce a rule that we prefer to use function myFunc() over const myFunc = () => {} for functions that are not callbacks or part of closures like in arr.map(fn).

I am not sure if there is an easy to also detect if the function is a callback signature or closure, but I would assume some configuration is also possible with AST parsing for things like making sure map, filter, reduce, find etc (the more common uses, omitted for brevity) would be covered.