[julia-users] Nullable parametric types

[Darwin Darakananda]

Hi all,

I'm in the process of replacing my Union{Nothing, T} annotations to 
Nullable{T}, but I'm getting stuck when T is a parametric type.  For 
example, replacing the function

function myfunc(v::Union{Nothing, Vector})
    ...
end

with

function myfunc(v::Nullable{Vector})
    ...
end

makes it completely uncallable since any vector I pass in comes with an 
eltype parameter and Julia's type parameters are invariant.  For functions 
or types that only have a couple Nullable types, I can do something like

function myfunc{T}(v::Nullable{Vector{T}})
    ...
end

type MyType{T}
   v::Nullable{Vector{T}
end

but that gets very ugly when you have a large number of nullable types. 
 Does anyone know of a cleaner way to do this?

Thanks,

Darwin