Queries

Every front end application will need some amount of calculated information derived from the state. As a rule of thumb: if you can calculate it, you should. Keep your state as lean and normalized as is reasonable, and use queries for everything you can.

Syntax

const myQuery = O.query()

.with({ your, dependencies, here })

.as((o) => 'your result here')

Dependencies

The .with({ ... }) call allows you to specify any dependencies your query has. Queries cannot depend on commands, only state and other queries.

Query Body

Your query body is just a function with a special first argument: "little o." This special first argument will contain resolved versions of whatever dependencies you specify. Your query body must be a pure function: no side effects! It should only use the dependencies supplied, and it must always return a value.