I want to use an array of Set of integers in Julia, but when I look a the type of each element, it is not a Set, Why ?
typeof(fill(Set{Int64}[],3)[2])
returns
Array{Set{Int64},1}
and not
Set{Int64}
If I used primitive types, for example,
typeof([1,2][1]) # returns Int64
but
typeof([Set{Int64}[],Set{Int64}[]][1]) # returns Array{Set{Int64},1}
Why there is a Array enclosing Set{Int64}
You wrote
typeof(fill(Set{Int64}[],3)[2])
Set{Int}[] is another way of writing Vector{Set{Int}}.
Generally this way makes more sense when usd on a nonempty array construction like Int128[1,2,3]
You probably wanted Set{Int}() to get a single set.
Check typeof(fill(Set{Int64}(), 3)[2])
However this will fill the array with 3 references to the same set. So mutating one will mutate them all. Rarely what you want.
Probably what you really wanted was:
[Set{Int}() for _ in 1:3]