I was mostly excited about slice patterns because of a pattern I wanted to be able to write:

    some_collection.windows(2).filter(|[a,b]|a==b).map(|[a, _] |a).collect();

Turns out the compiler rejects that with a "refutable pattern" error, because the args part of the filter/map closures do not handle the situation where the slice could be empty, which AFAIK can not occur when using windows/chunks/...

Maybe there has to be some special case handling for this pattern to be valid?