How would one name a function type called by a certain event? Instances of this function type would get called when a certain key is pressed. It isn't strictly an event handler type, because it doesn't have to handle the event. It might simply just want to be aware of the event. There can be multiple functions with this type listening for the same keystroke event.
I currently am using
SpecificKeystrokeListener although that's not really correct as it doesn't listen, it is merely being notified.
For what it's worth, I am using Rust - though this applies to other languages as well. As an example:
type ResetFn = fn (this: *const device) -> ReturnStatus;