问题描述

export interface ModelConfig<S = any, SS = S> {
  name?: string,
  state: S,
  baseReducer?: (state: SS, action: Action) => SS,
  reducers?: ModelReducers<S>,
  effects?: ModelEffects<any> | ((dispatch: RematchDispatch) => ModelEffects<any>),
}

这种 <S = any, SS = S> 的是什么东西呀？

求大佬解答