Globally register a callback f for event-type with key key. Replaces previously installed trigger with event-type and key.

When a matching event is succesfully committed to repository, callback will be called as (f repository target-aggregate event), where target-aggregate is the target of event in the state prior to commit.

Global registry of triggers. Atom containing map of event-type -> key -> callback.

Wrap a repository with triggers. The standard rill.wheel repository constructors call this wrapper so library users should not have to call this function.