AnyReducer.pullback variant w/o Environment

[heyltsjay]

I just completed migrating our app to ReducerProtocol:

• ~60 reducers
• migrated from leaf --> root
• nearly all environments migrated to @Dependency

I was surprised to see that there wasn't an AnyReducer.pullback variant that didn't take an environment, since I never needed to use one. I assumed this would be the typical migration path, but maybe it's expected to leave more non-@Dependency dependencies behind.

This is a very small and short-lived convenience, so not sure it warrants discussion, but was encouraged to post one by @mbrandonw

After migrating leaves, my next-higher reducer looked like this until I migrated up one level.

static let reducer = Reducer.combine([
   AnyReducer {
       FeatureLeafA.Reducer()
   }
   .pullback(
     state: \.featureLeafA,
     action: /Action.featureLeafA,
     environment: {  _ in }
    ),
    AnyReducer {
       FeatureLeafB.Reducer()
   }
   .pullback(
     state: \.featureLeafB,
     action: /Action.featureLeafB,
     environment: {  _ in }
    ),
    Reducer { ... }
])

[stephencelis]

@heyltsjay While we originally had this overload available, what we found was you'd probably never compile this step since it's so close to the final answer.

For example, if you start here:

AnyReducer {
  FeatureLeafA.Reducer()
}
.pullback(
  state: \.featureLeafA,
  action: /Action.featureLeafA,
  environment: {  _ in }
)

And wanted to move the pullback inside to the protocolized layer:

AnyReducer {
  FeatureLeafA.Reducer()
    .pullback(state: \.featureLeafA, action: /Action.featureLeafA)
)

You're basically already at Scope:

AnyReducer {
  Scope(state: \.featureLeafA, action: /Action.featureLeafA) {
    FeatureLeafA.Reducer()
  }
)

And so there's very little reason to use that other pullback.

Definitely interested to hear if other folks had similar experiences, though!

[heyltsjay]

Ah ok that makes sense. I was a little glued to the migration guide while I was onboarding and didn't quite grasp yet that i could stuff a fully-realized scoped reducer in AnyReducer.

May be worth a small addendum at the end of the optional and pullback section. Thanks @stephencelis