• (Slides)[http://llama.freegeek.org/~wren/pubs/unification-intro-mcmaster.pdf]
  • (Slides)[http://llama.freegeek.org/~wren/pubs/unification-opt-mcmaster.pdf]
  • (Implementation)[http://hackage.haskell.org/package/unification-fd]


Unification has many diverse applications, from logic programming and implementing type analysis, to parsing natural language and performing case analysis for algebraic data types. However, naive implementation is horrifically inefficient. The inefficiencies are not due to mere constant factors, but rather unification plays on the boundary of decidability and the unwary can easy fall prey to a number of asymptotic inefficiencies. These inefficiencies and many optimizations to avoid them are well-known within the community, but this knowledge is folklore and seldom written down or taught. I will be sharing some of these folklore techniques, as well as a few optimizations which are (to my knowledge) novel.