// First, you create the middleware, which needs to know the type of your `State`.
let thunkMiddleware: Middleware<MyState> = createThunkMiddleware()

// Note that it can perfectly live with other middleware in the chain.
let store = Store<MyState>(reducer: reducer, state: nil, middleware: [thunkMiddleware])

// A thunk represents an action that can perform side effects, access the current state of the store, and dispatch new actions, as if it were a ReSwift middleware.
let thunk = Thunk<MyState> { dispatch, getState in 
    if getState!.loading {
        return
    }
    dispatch(RequestStart())
    api.getSomething() { something in
        if something != nil {
            dispatch(RequestSuccess(something))
        } else {
            dispatch(RequestError())
        }
    }
}

// A thunk can also be a function if you want to pass on parameters
func thunkWithParams(_ identifier: Int) -> Thunk<MyState> {
    return Thunk<MyState> { dispatch, getState in
        guard let state = getState() else { return }
        
        if state.loading {
            return
        }
        
        api.getSomethingWithId(identifier) { something in
            if something != nil {
                dispatch(RequestSuccess(something))
            } else {
                dispatch(RequestError())
            }
        }
    }
}

// As the thunk type conforms to the `Action` protocol, you can dispatch it as usual, without having to implement an overload of the `dispatch` function inside the ReSwift library.
store.dispatch(thunk)

// You can do the same with the Thunk that requires parameters, like so
store.dispatch(thunkWithParams(10))

// Note that these actions won't reach the reducers, instead, the thunks middleware will catch it and execute its body, producing the desired side effects.

ExpectThunk(thunk)
    .getsState(RequestState(loading: false))
    // If the action is Equatable it will be asserted for equality with `dispatches`.
    .dispatches(RequestStart())
    .dispatches { action in
        XCTAssert(action.something == expectedSomething)
    }
    .wait() // or simply run() for synchronous flows

import PackageDescription

let package = Package(
    [...]
    dependencies: [
        .Package(url: "https://github.com/ReSwift/ReSwift-Thunk.git", majorVersion: XYZ)
    ]
)