Defining a subclass

[heliosdrm]

@Niall

The notation Vector{<:Complex} is new to me - I’m just not sure what it would bring me, since Complex doesn’t (can’t) have any subtypes. What am I missing?

Sorry, I didn’t use the correct words: Complex is not an abstract type, but it is a parametric type. That means that it is not either a concrete type, as you can see when you create actual complex numbers:

julia> typeof(1+1im)
Complex{Int64}

julia> typeof(1.0 + 1.0im)
ComplexF64 (alias for Complex{Float64})

None of them is “just” Complex: the concrete types also carry information of the type of numbers contained (real and imaginary parts).

Now, about the notation Vector{<:Complex}, the first few posts of the following discussion can help you (the discussion is about the abstract type Number, not about the parametric type Complex, but the situation is analogous):

Why [1, 2, 3] is not a Vector{Number}?

I don’t understand this: julia> isa([1,2,3], Vector{Number}) false Each 1, 2, or 3 is certainly a Number: julia> isa(1, Number) true It is illogical to say [1, 2, 3] is not Vector{Number} when each element is a Number.