Typescript: How to type the Dispatch in Redux

I got a bit further!

Dispatch is an event function, so got this to work:

interface IAllAssets {
  type: IActions['GET_ALL_ASSETS'];
  assets?: IAsset[];
  loading: boolean;
}

// ACTIONS
// Fetch assets from Nomics API V1.
export const fetchAllAssets = () => (dispatch: (arg: IAllAssets) => (IAllAssets)) =>
{
   dispatch(actionGetAllAssets());
   return fetchAll([getPrices(), getAvailableSupply()]).then((responses) =>
       dispatch(actionSetAllAssets(formatAssets(responses))));
}

However I'd still like to create a dispatch type, something like:

interface IAllAssetsDispatch {
  dispatch: (arg: IAllAssets) => (IAllAssets)
}

export const fetchAllAssets = () => (dispatch: IAllAssetsDispatch) => {

But this produces the same lacks a call signature error.

GOT IT!

Forgot about type that's what I needed to use instead of interface for functions:

type DispatchAllAssets = (arg: IAllAssets) => (IAllAssets);

type DispatchMarketPrices = (arg: ISetMarket) => (ISetMarket);

type DispatchAddCoin = (arg: ICoinPortfolio) => (ICoinPortfolio);

type DispatchAddCoins = (arg: ICoinsPortfolio) => (ICoinsPortfolio);

// ACTIONS
// Fetch assets from Nomics API V1.
export const fetchAllAssets = () => (dispatch: DispatchAllAssets) => {
  dispatch(actionGetAllAssets());
  return fetchAll([getPrices(), getAvailableSupply()]).then((responses) =>
    dispatch(actionSetAllAssets(formatAssets(responses))));
}

// Fetch USD, USDC & USDT markets to filter out Exchange List.
export const fetchMarketPrices = (asset: string) => (dispatch: DispatchMarketPrices) => {
  dispatch(actionGetMarketPrices);
  return getMarkets().then((res) => {
    if (res && res.marketUSD && res.marketUSDC && res.marketUSDT) {
      const exchangesForAsset = combineExchangeData(asset, res);
      return dispatch(actionSetMarketPrices(exchangesForAsset));
    }
    else {
      return dispatch(actionSetMarketPrices([]));
    }
  });
}

The Redux typings have a generic Dispatch<A> type you can use, where A is the type of action.

export const fetchAllAssets = () => (dispatch: Dispatch<IGetAllAssets | ISetAllAssets>) => {
  // ...
}