create-immutable-selector

createImmutableSelector is a customized version of reselect's createSelector with Immutable.is as equality check.

import createImmutableSelector from "create-immutable-selector";

const shopItemsSelector = state => state.getIn(["shop", "items"]);
const taxPercentSelector = state => state.getIn(["shop", "taxPercent"]);

const subtotalSelector = createImmutableSelector(shopItemsSelector, items =>
  items.reduce((acc, item) => acc + item.value, 0)
);