Embedding goal-directed evaluation through transformation
Peter H. Mills, Clinton L. Jeffery · 2016
Goal-directed evaluation is a paradigm that combines the power of generators with backtracking search. In goal-directed evaluation every expression is a generator that produces a sequence of values or fails, and operations search to find successful results over the product space of their operands. Introduced in the influential dynamic language Icon and later refined in its object-oriented descendent Unicon, goal-directed evaluation is difficult to formalize and implement. In particular grafting goal-directed evaluation onto other languages in a manner that provides seamless interoperability has remained an elusive challenge.