Proposal: support union types

[aitorllj93]

While navigating through the Unreal Blueprint API documentation to get some inspiration for our docs, I noticed for some Nodes they do support Union types. I think this could be a nice to have feature, specially if we include structured data support, but also for some generic functions which might accept ie both float & integer values

[bhouston]

I was thinking to keep the node implementations simple, we could have fixed input and output types on the nodes, but the UI could map different nodes onto each other in the UI. Basically this would be how languages like C# have multiple functions with the same name, but with different input parameters. Would pushing this polymorphism (a kind of it) into the UI layer of the graph editor be okay?

[aitorllj93]

I understand what you mean, and I think keeping the node implementations just with the Object datatype would be enough. Anyway, even if we keep this "object typing" in the graph editor level, this would need additional metadata properties to be able work with, after all, the graph editor uses the JSONSpec to determine what to render. Maybe we can think about some way of "pluggable" metadata so we can reuse core node definitions by extending their configuration or something like that