The hunger of Hadar spell (PHB, p. 251) creates a black void of darkness, which cannot be penetrated by light. This means that no one can see in, and those inside cannot see at all, which is a handy way to damage and control enemies since they don’t know which way is out.
This also means that characters cannot easily attack those inside.
The Devil’s Sight eldritch invocation, however, enables a warlock to see normally in magical and non-magical darkness.
Does this enable the warlock to see into the area of blackness created by hunger of Hadar and attack creatures inside? Are there any other sight mechanics that allow someone to see in or out of the spell?