Store

A wrapper around JavaScript Map.

Store adds some additional functionality on top of Map.

1. Store distinguishes between initializing (init) a (key, value) pair and resetting the key to a different value (set), whereas Map doesn't. This means you can use the Store abstraction without having to check whether the key already exists. This is because the method that you call (init or set) marks your intention and does it for you.

2. You can use the Store methods in a functional programming pattern, which you can't with Map. For instance, you can create a new function const getPurse = Store.get and you can do myArray.map(Store.get). You can't do either of these with Map, because the Map methods are not tied to a particular Map instance.

See @agoric/weak-store for the wrapper around JavaScript's WeakMap abstraction.