`key` property

[coot]

The key property is write only property, that can be placed on props, but react warns if you're trying to access it from within a component. It would be nice to find a proper way to encode this. Better than just adding key to property type. The simplest soluting would be to have an unsafe method:

setKey :: forall a. String -> a -> a

Another solution would be to have a a class with a setKey method, but then for every prop type one would have to implement it (maybe generic deriving could help with this).

Any other ideas?

[coot]

Instead of forall a. String -> a -> a we could just have forall r. String -> {|r} -> {|r}, that would be safer, but the Union type would be excluded.