> Copying things by default isn’t a very good strategy for a language used to
> do linear algebra on large arrays.
I didn't say I want do copy arrays by default. I don't want to change behavior
of existing types or functions. All I wanted express that Julia lacks of clear
semantics expressing what is value and what is a reference to value, implying
what is copied and what is hold by GC and passed via reference to function.
I don't like imposing reference when declaring a (mutable) "type". But I don't
want to change behavior of existing classes, so you want Array{T} to be still a
reference, however it should be explicitly stated it is a reference, i.e. using
a test is Array is some concrete type of Ref{T}.
But I can imagine I want to have some PlainArray{Float64,4} which is value type
and matches exactly machine vector. In such case I don't want such type to be
reference, but now I don't have a choice Array is a reference, period.
So when I want to have separation between value and reference I do:
type Point
x; y
end
typealias PointRef Ref{Point}
If I want to declare type that's already a reference to some anonymous
(private) value type I do:
@ref type Point
x; y
end
This make Point to be type alias for Ref{anonymous_Point_val_type}.
Finally const (immutable) should be completely detached from being or not being
a reference, e.g.:
@const @ref type SomeType
..
end
But still I should be able to explicitly choose which fields are mutable and
which are not.
type OtherType
const a::Int
b::Int
end
I know Julia's target is scientific computation, however it (she?) has great
potential of being general purpose language, much better than Go, Rust or Swift.
--Adam
