Does anyone knows what the type arguments refers t...

# react

[Big Chungus]

Does anyone knows what the type arguments refers to in these functions of Redux wrappers?:

external fun <A, T1, R> compose(function1: (T1) -> R, function2: (A) -> T1): (A) -> R

&

external fun <S, A, R> createStore(
    reducer: Reducer<S, A>,
    preloadedState: S,
    enhancer: Enhancer<S, Action, Action, A, R>
): Store<S, A, R>

R especially

[Robert Jaros]

From the sources and this description https://github.com/lawik123/kotlin-poc-frontend-react-redux my guess is R == WrapperAction

[Big Chungus]

Just tested. You are correct

[Robert Jaros]

not that I know what it really is 😉

[Big Chungus]

That makes two of us

[Big Chungus]

But hey, as long as it compiles, right? 😄

[Joffrey]

Not sure if that is your last question, but if you're wondering what WrapperAction is, I believe I have found the answer.

It's basically a built-in subinterface of the default redux Action that provides a default value for the type field, so that you can use plain data classes as actions.

To be more precise, as far as I understood, Store<S, A, R> defines A as the input action type for dispatch() and the reducer, and R as the return type of dispatch().
When using enhancers, you can basically "enhance" the store to accept a new action type instead of A and return a new type from dispatch() instead of R.

There is a built-in enhancer provided by the kotlin-redux wrapper, which makes WrapperAction the new return type of dispatch and RAction the new input type of dispatch and the reducer. Internally, it simply wraps the reducer and dispatch.