This kind of languages is extremely useful, since many problems maps nicely to a logical or relational model. I'm using a PAIP-style embedded Prolog and an opt

This kind of languages is extremely useful, since many problems maps nicely to a logical or relational model. I'm using a PAIP-style embedded Prolog and an optimised Datalog for fast prototyping compiler passes - things like alias analysis, implementing type systems (e.g., Hindley-Milner maps to Prolog naturally), constant folding, DCE, Array-SSA, and many more. Harlan is using cKanren for region inference and some other passes. A nice motivational paper (on Datalog): http://www.cs.cmu.edu/~aldrich/courses/654/tools/bierhoff-bddbddb-05.pdf http://www.cs.cmu.edu/~aldrich/courses/654/tools/bierhoff-bd...