HiLog is a logical formalism that provides higher-order and meta-programming features in a computationally tractable first-order semantics.
Relevance
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.
For More Information
More information on HiLog can be found in http://flora.sourceforge.net/aboutHiLog.php. HiLog has been implemented in the following systems:
FLORA-2
XSB.
HiLog also underlies Common Logic
RIFWG contact: MichaelKifer.