Horn Clause logic: the knowns and the unknowns In this talk, I will survey old and new results on Coalgebraic logic programming -- a recently suggested dialect of logic programming based on Horn clause logic and reflecting the categorical (coalgebraic) semantics of logic programming introduced by myself and John Power in our CALCO'11 paper. I will give an overview of the trajectory of this research from 2011 to 2017, focusing on categorical, coalgebraic, algorithmic and type-theoretic discoveries myself and various talented colleagues made on the way.