Re: [julia-users] Is there a way to define abstract type from a type in base.jl

[Roger Luo]

Thanks,I've read about the arrays,but just don't know how to define some
existed type.
though a type may be define as:
type a{T<:Integer}<:Real
xxx
end

but that's will work in my function.I tried to pass different types into a
function, so I asked this question.
still do not understand why can define a existed type become a subtype of
some other type?

2015-09-25 15:11 GMT+08:00 Mauro <mauro...@runbox.com>:

> Julia's parametric types are invariant (except tuples).  To figure out
> what that means have a read through
>
> http://docs.julialang.org/en/release-0.4/manual/types/#parametric-composite-types
>
> > How to make Array{BigFloat,1}<:Array{Real,1}?
>
> This is always false (that is invariance).  But presumably you want a
> method which takes any Array with eltype<:Real, try something like:
>
> julia> f{T<:Real}(ar::Array{T,1}) = typeof(ar)
> f (generic function with 1 method)
>
> julia> f(Array(BigFloat, 2))
> Array{BigFloat,1}
>