Hands-On Design Patterns with React Native

Call me Maybe

There is one place in our code that begs for simplification. Take a look at the taskSelector:

export const tasksSelector = state => state.tasks;export const tasksEntitiesSelector = createSelector(    tasksSelector,    tasks => (tasks ? tasks.get('entities') : null));export const getTaskById = taskId => createSelector(    tasksEntitiesSelector,    entities => (entities        ? entities.find(task => task.id === taskId)        : null)); 

We constantly fear whether we received something or null. This is a perfect case to delegate such work to the Maybe monad. Once we implement Maybe, the following code will be fully functional:

import Maybe from '../../../../utils/Maybe';export const tasksSelector = state => Maybe(state).map(x => x.tasks);export const  ...