Projection

A Projection<T> is a value that can be read synchronously or reactively. It is a store itself, so derived(someProjection, ...) works as well as derived(someProjection.$, ...).

type Projection<T> = Readable<T> & {
  get: () => T          // synchronous "hot" snapshot
  $: Readable<T>        // a Svelte readable for subscriptions / $-syntax
}

const display = app.use(Profiles).display(pubkey)

display.get()           // string, right now
display.$               // Readable<string>, for `$display` in a component

// Wrap a Readable into a Projection (default getter is hot-path aware)
projection<T>($: Readable<T>, get?): Projection<T>

// Derive one Projection from another, preserving both access modes
projectFrom<S, U>(src: Projection<S>, read: ($: S) => U): Projection<U>

The default get is getter($), which caches the store value on hot paths, so .get() is cheap to call repeatedly.