Back to the original subject, because I think there's some value in
summarizing it.
1. Variance. It is somewhat unintuitive to a lot of newcomers that in Julia
Array{Real} is a concrete type and Array{Int} is not a subtype of it. It
might be possible to make parametric types in Julia covariant by default,
but then one must either come up with a different way of writing the
concrete type currently known as Array{Real} or allow concrete parametric
types like Array{Real} to have subtypes, namely Array{T} for each T <: Real.
2. Restricting type parameters to concrete types. The variance issue was a
bit of a red herring. What Oliver was really after, it seems (correct me if
I'm wrong), was being able to ensure that the T in Array{T} is always a
concrete type.
On Wed, Apr 30, 2014 at 4:02 PM, Oliver Woodford
<[email protected]>wrote:
> On Wednesday, April 30, 2014 6:47:43 PM UTC+1, Jacob Quinn wrote:
>>
>> I apologize if you felt it was a personal attack, because it certainly
>> wasn't intended as such. I've always appreciated the Julia community and
>> how welcoming and encouraging it is and I wouldn't want to tarnish that
>> reputation. I'm far from the best person to comment on the particularities
>> of type invariance/co-variance/contra-variance, but I still enjoy
>> contributing to discussions when I can. In this case, I felt my own
>> experience getting comfortable with parametric types could be useful.
>>
>> -Jacob
>>
>
> I don't think it was a personal attack - I'm sorry I used the word because
> you have missed the point I was making as a result. I am not after an
> apology. I don't want you to stop providing your valuable experience with
> anyone. Your testimony could be told to every person about to learn Julia -
> that would be great. However you shared it when we were halfway through a
> debate about a particular point, that we could perfectly well discuss on
> its own merits, drawing attention away from that and on to my experience,
> which at that point seems irrelevant. The point I made in my last post, and
> that I make again now, is that that approach to debate doesn't do us (me,
> you, this group, society) any favours - it's akin to focussing on
> personality not policy in politics, and what does that get us? IMO it
> simply wasn't the right moment for you to share that experience. All I
> would like is an understanding and acknowledgement of that point. And if
> you don't get it or disagree, not to worry. Please do continue to
> contribute in whatever way you feel is appropriate - and if I have had a
> positive impact in that respect, great. This will be my last message on the
> subject (trying to make the world a better place though sometimes it
> doesn't feel like it), so feel free to have the last word.
>
