IfLetStore

When the underlying state is non-nil, the then closure will be performed with a Store that holds onto non-optional state, and otherwise the else closure will be performed.

This is useful for deciding between two views to show depending on an optional piece of state:

IfLetStore(
  store.scope(state: \.results, action: { .results($0) })
) {
  SearchResultsView(store: $0)
} else: {
  Text("Loading search results...")
}