On Sat, Dec 4, 2010 at 6:39 PM, Jules <julesjac...@gmail.com> wrote: > Interesting. Is Byrd's dissertation available online?
Yes I added that and several other resource links to the bottom of the project's description on the GitHub repo. David > On Dec 4, 9:41 pm, David Nolen <dnolen.li...@gmail.com> wrote: > > I announced it earlier this week on Twitter, but it's now come far along > > enough to be usable. You can write fun stuff like the following: > > > > (defn likes > > [x y] > > (cond-e > > ((== x 'john) (== y 'mary)) > > ((== x 'mary) (== y 'john)))) > > > > (defn musician [x] > > (cond-e > > ((== x 'john)) > > ((== x 'bob)))) > > > > (run* [q] > > (likes q 'mary) > > (musician q)) > > ;; [john] > > > > (run* [q] > > (musician q)) > > ;; [john bob] > > > > (run* [q] > > (exist [x y] > > (likes x y) > > (== [x y] q))) > > ;; [[john mary] [mary john]] > > > > My inspiration to start on this was Jim Duey's implementation. However I > had > > two specific goals - > > > > * Focus on performance. While developing I compared performance against > > miniKanren under Racket - I made sure the Clojure implementation ran at > > least as fast, and in many cases it runs quite a bit faster > > * Implement "growable" sequences without resorting to Scheme's dotted > pairs. > > This required me to develop a new protocol in which iteration might > return a > > logic var instead of nil or a Seq. > > > > The implementation started with the one described William Byrd's > > dissertation. However a considerable number of changes were made- > > > > * substitutions are implemented as a protocol and a defrecord > > * substitutions internally use a PersistentHashMap as well as > > PersistentVector (for debugging) > > * supports unification of all the Clojure data structures supported by > > clojure.walk > > * goal and goal constructors are implements as deftypes (Mzero, Unit, > > Choice, Inc) and those implement IMPlus and IBind protocols. > > > > The code base is compact, some ~450 lines of Clojure. > > > > Future directions: > > * Friendlier interface for defining facts and running queries > > * There are many great ideas in William Byrd's thesis that need looking > > into. In particular I'm interested in tabling. > > * Investigating replacing the PersistentHashMap with a Skew Binary Random > > Access List or a Finger Tree. This would speed up the performance of the > > most expensive functions in the system, walk. In the Scheme > implementations > > SBRALs can lead to 2.5X-100X in performance. > > * Modifying the core macros to optimize logic programs. > > * Parallel logic programming. > > > > Source and more info here,https://github.com/swannodette/logos. > > -- > 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<clojure%2bunsubscr...@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 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
