Immutable Collections - anyone else *need* this?

[shiftkey]

Octokit.NET uses SimpleJson heavily, and with the license changes to Microsoft.Bcl.Immutable we can now use the System.Collections.Immutable namespaces rather than our custom implementations

BUT

There's a whole bunch of changes to how you can create ImmutableColllections (that is, the concrete implementations of IImmutableCollection) that break existing assumptions.

public interface IImmutableDictionary<TKey, TValue> 
    : IReadOnlyDictionary<TKey, TValue>,
      IReadOnlyCollection<KeyValuePair<TKey, TValue>>,
      IEnumerable<KeyValuePair<TKey, TValue>>, 
      IEnumerable

versus

public interface IDictionary<TKey, TValue> 
    : ICollection<KeyValuePair<TKey, TValue>>, 
      IEnumerable<KeyValuePair<TKey, TValue>>,
      IEnumerable

for example.

I've made some progress here on getting this scenario running, but it's not ready for a review or even a PR.

Thoughts?

[prabirshrestha]

I would definitely be interested in getting this in the core.

• Since IImmutableDictionary requires new references, we would need an option to disable/enable it. (Default should be disabled). Would need something like #define SIMPLE_JSON_IMMUTABLE_COLLECTIONS.
• Also we can't use vars :( as we need to support the ISO-2 C# lang spec.
• Any reflection utils changes should go in this reflection-utils first before I merge it here. (But that is done once we are sure we are gonna use it in simple-json. So you can send PR in reflection-utils once we decide to merge it here)
• also would be good to squeeze in ImmutableList<T> for arrays.

I will be gone for MVP summit this week, so not sure if I will be able to look at your PRs or dive into this more, but please feel free to submit a PR.

[shiftkey]

@prabirshrestha i'll also be around for MVP summit. It's not urgent, but I'll keep that feedback in mind...

[prabirshrestha]

@shiftkey cool. we should meet. feel free to ping me on twitter. same username as github.