Adding some convenient initialisers

[rkreutz]

Hey there, I believe this is a rather straightforward PR.

I've added a few convenience initialisers so I could combine different Reducers for different context (actions), them being:

• init(forAction:handler) & init(forActions:handler) which will execute the Reducer's handler if it receives the provided action(s). It handles actions with or without (Void) associated values.
• init(bindingAction:to:handler) & init(bindingAction:to:handler) which will automatically set an actions associated value to a key path in the state, optionally providing a handler to further customise state and/or trigger different side effects.

I thought this would be worth sharing :)

[stephencelis]

Hey @rkreutz! This one slipped by, sorry about that! 😄 Holiday season must've caught us off guard.

These are definitely fun! We have some other reducers that we'd like to bring into the core library, but think it'll be a matter of motivating them with examples and case studies.

If you have some interesting uses of these initializers we'd definitely take a PR for a case study first, and if we find folks are copying and pasting the logic into their code bases a lot we'd definitely consider moving them into the library itself!

Since you opened this PR I believe we opened the discussions tab on this repo. You might be interested in re-sharing your helpers there. Maybe with some examples that can be worked into a case study!

Okay to close this out in favor of those directions?

[rkreutz]

hey @stephencelis,

yeah makes total sense, I'll open a thread on the discussion tab with these, no problem. Thanks for the clarification.

I'll close this now.

[rkreutz]

#450