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

[Mauro]

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}