Add annotations to Recursive via ZEnvironment about zio-prelude

[adamgfraser]

Will add this.

[DamianReeves]

After some discussion with Adam it feels like a data type which knows how to combine annotations is needed. I pushed up a first pass at this as discussed with John.

[adamgfraser]

The AnnotationMap approach with an associative combining operation is certainly a valuable one for specific cases. I wonder if we should stick with the ZEnvironment approach here, which I think is a bit more general (basically just supporting having the concept of multiple annotations).

The annotation map approach could be used by implementers of specific recursive data types when they wanted the properties that went along with it (e.g. primitive annotations only exist at the "leaves" and annotations at the "branches" are always result of composition of the corresponding leaves).

[DamianReeves]

Good point. I am working on a couple of examples of tree structures which we would want to annotate, maybe these use-cases will help us settle on an API.

[DamianReeves]

The AnnotationMap approach with an associative combining operation is certainly a valuable one for specific cases. I wonder if we should stick with the ZEnvironment approach here, which I think is a bit more general (basically just supporting having the concept of multiple annotations).

Is it maybe possible to combine the AnnotationMap and ZEnvironment into one Annotations data structure which supports both scenarios?

[adamgfraser]

I think you could build that logic on top of ZEnvironment by defining a function (ZEnvironment[Annotations], ZEnvironment[Annotations]) => ZEnvironment[Annotations].