Update the example to leverage isa? hierarchies and allow prefer-poly, a la prefer-method: https://stackoverflow.com/questions/53329709/dispatching-function-calls-on-different-formats-of-maps/53354967#53354967
V/r John On Saturday, November 17, 2018 at 5:09:09 PM UTC-5, John Newman wrote: > > In order to answer a SO question I ended up whipping up a quick and dirty > implementation of predicate dispatch here > <https://stackoverflow.com/questions/53329709/dispatching-function-calls-on-different-formats-of-maps/53354967#53354967>. > > (unless I'm misunderstanding the definition of "predicate dispatch") > > If you know your dispatch set is going to be small, a first-one-wins > strategy should be good enough, right? And we can't really measure the > complexity of a user's supplied predicate function a priori anyway, so if > an isa? hierarchy isn't supplied, we might as well just check them in the > order they're provided from the user and let the first one win, right? > > V/r > > John > > On Thursday, April 14, 2011 at 11:25:48 AM UTC-4, David Nolen wrote: >> >> When things begin to get recursive you may be on the right track :D >> >> Initially I was going to implement Nominal Logic Programming for Logos a >> la William Byrd's dissertation, but I realized that his implementation >> requires pattern matching. All the pattern matching libs I've seen thus far >> for Clojure are too naive and too slow. Even more importantly pattern >> matching is subsumed by predicate dispatch (CiteSeerX — Efficient >> Predicate Dispatching >> <http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.47.4553>). >> >> Rich Hickey mentioned many moons ago that he'd like to see a predicate >> dispatch implementation for Clojure that didn't have the kind of hardwiring >> found in the Chambers/Chen paper. He suggested investigating Datalog. After >> much reading, I've decided that a runtime in-memory Datalog that handles >> dispatching is going to be too slow for many useful scenarios (an efficient >> Datalog based on Binary Decision Diagrams might be possible, but this is an >> incredibly complex undertaking in itself, meh). >> >> What we want is Standard MLs efficient compilation from decision diagrams >> to switch statements (CiteSeerX — Optimizing Pattern Matching >> <http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.6.5507>). >> However Standard ML (Haskell, OCaml, Scala as well) pattern-matching has >> issues with order among other things (Programming in Standard ML >> <http://www.cs.cmu.edu/~rwh/smlbook/book.pdf>). >> >> What if we allow a logic engine to drive the compilation of the decision >> diagram? This would be done by users mapping logic predicates to Clojure >> predicate functions. Relationships between predicates can be added to the >> logic engine allowing compilation to produce a very efficient decision >> diagram. Nothing is hard coded, everything is driven by the kinds of >> predicates and relationships between predicates that a user actually cares >> about. >> >> All this is to say that this means Logos needs the ability to load >> database of facts, index those facts, and to accept new facts and >> relationships and update accordingly. So this going to happen sooner rather >> then later. >> >> I welcome any feedback from anyone who has thoughts on this approach to >> implementing predicate dispatch efficiently! >> >> Some thoughts on what this might look like is evolving here, >> https://github.com/swannodette/match/wiki/Crazy-Ideas. >> >> David >> >> On Mon, Apr 11, 2011 at 3:08 PM, David Nolen <dnolen...@gmail.com> wrote: >> >>> On Mon, Apr 11, 2011 at 2:01 PM, Vagif Verdi <vagif...@gmail.com> wrote: >>> >>>> Can it be used as an inference (rule) engine ? >>> >>> >>> If you mean in the same way that you can build inference (rule) engines >>> in Prolog - I don't see why not. >>> >>> However there is a bit of work to be done in order to make building >>> efficient rule engines easier: >>> >>> * Be able to load a database (aka Clojure collection) of facts >>> * Indexing of facts >>> * Intelligently use indexed facts >>> >>> Currently I'm a bit more interested in exploring type inference (via >>> nominal logic) so I'm not sure when exactly I'll get to these, tho I'll >>> gladly take patches from people who want such features sooner rather than >>> later :) >>> >>> David >>> >> >> -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
