HiLog is a logical formalism that provides higher-order and meta-programming features in a computationally tractable first-order semantics.
Higher-orderness has been discussed extensively in RIFWG, and HiLog is one of the primary example of a successful deployment of these ideas in practical settings.
Impact on Design
Experience with the implementations of HiLog can be very valuable for the design of RIF.
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HiLog also underlies Common Logic
RIFWG contact: MichaelKifer.