Wondering how to get field state from multiple fields at once? People coming from Redux-Form might be wondering where the equivalent of Redux Form's Fields component is, as a way to get state from several fields at once. The answer is that it's not included in the library because it's so easy to write one recursively composing Field components together.

And you see the problem, concerns are so simple that they do not deserve a full guide. Concerns are mixins, if you are a Ruby programmer, you already know what a mixin is and their use case to modularize APIs.