Kinds of containers

[Ice Cream Man via Digitalmars-d]

On Wednesday, 21 October 2015 at 14:06:43 UTC, Jonathan M Davis 
wrote:
>> 1. Functional containers.
>
> I fully expect that these have their place, but I honestly have 
> no idea what they would be. When I've used functional 
> languages, I've only ever found these attributes to be a royal 
> pain to deal with, not a benefit. From what I've seen, 
> containers are the sort of thing that almost always always need 
> to be mutable to be of any real benefit. Upon occasion, 
> constructing a container up front and then never tweaking it 
> after that is useful, but that's pretty rare from what I've 
> seen.
>
> The only cases that I can think of where this could be really 
> beneficial would be something like strings, and we're using 
> arrays for those currently (though they are arguably functional 
> containers given that they have immutable elements).

I've found immutable containers useful when working with 
configuration files. There are only a few places in a program 
where you want to actively change values in a configuration files 
(configure the values). For these instances it's useful for the 
GUI or whatever to grab a mutable container to work with. For all 
other areas, immutable containers are very helpful in ensuring 
nobody accidentally modifies something they shouldn't be outside 
of the provided sandboxes.