block5.ts

// (action, state) => ({ actions, state });
const reducer = State.match({
  FetchingDimensions: () =>
    Action.match({
      FetchedDimensions: ({ dimensions }) =>
        checkDimensionsValid(dimensions)
          ? {
              state: State.Uploading(),
              actions: [Action.Upload()]
            }
          : {
              state: State.Invalid(),
              actions: []
            }
    })
});