optimized immutable containers

[w0rp]

On Thursday, 4 July 2013 at 05:45:41 UTC, monarch_dodra wrote:
> Just to be clear, I didn't say it before: That behavior is a 
> bug, and is currently undergoing correction. Please don't relly 
> on it.

I see. Well, a garbage collected linked list is very easy to 
implement, so I suppose it's easy for you to get these semantics 
if you want them.

>> The operations on the types could use more qualifiers, though. 
>> Using them in pure functions would make it possible to 
>> implicitly convert them to immutable, which is a powerful 
>> thing indeed.
>
> Keep in mind that in D, const is "turtles all the way down", so 
> it is not possible to have an "immutable container of mutable 
> items". Once you give something the "const" handle, it is very 
> hard to strip it.

I am aware of how const and immutable work, and that's what I 
want. It's just nice that with a pure qualifier, you can 
sometimes build immutable data from functions returning mutable 
data without creating any copies.