It’s worth it to at least annotate argument types as AbstractVector or alike. Because it won’t be long before someone would like to pass an array view to a function that only accepts Vectors.
I would not recommend constraining the element type of collection at all because e.g. units from Unitful.jl do not subtype Number but may be used as number-like values in many circumstances.
I agree that it’s a bit disturbing, but couldn’t find a better solution 