Kinds of containers

[Timon Gehr via Digitalmars-d]

On 10/21/2015 07:25 PM, Andrei Alexandrescu wrote:
>
> It seems to me that's a departure from traditional persistent data
> structures.

I don't think so.

> Those have immutable elements;

Immutable insofar as the elements themselves don't change. It is easy to 
create a persistent list of immutable references to mutable data in 
Haskell, for instance.

> far as I can tell you discuss
> containers that only have immutable topology. -- Andrei

The topology as well as all the elements are immutable, just not in the 
'transitive qualifier' way. Immutable references to mutable data are 
useful, they just don't have built-in language support. Persistent data 
structures work perfectly fine with those.