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I'm a software engineer at Knewton who worked with Kenny on this project. We're not using Neo4j because of other unrelated constraints that have led us to writ

I'm a software engineer at Knewton who worked with Kenny on this project. We're not using Neo4j because of other unrelated constraints that have led us to write our own graph data store. Kenny's work implemented the "rule paralleling queries" approach you mention. I'm not sure about Prolog, but Java's Antlr library was really easy to use. Writing the parser+lexer infrastructure only took a few days. It wasn't quite as clean as using Antlr in a language like SML, but for implementing a parser in Java it was pretty great.

andrewcooke 15y ago
interesting, thanks (sorry for misunderstanding slightly). possibly related / useful in future - did you notice that neo4j's licence terms changed a while back? i can't remember the details, but i had avoided it in the past because of licensing and remember that the change seemed to be an improvement.
- espeed 15y ago
  The Neo4j community edition is now free and licensed under GPL (http://neo4j.org/download/ http://neo4j.org/download/), and they are working on an Enterprise license that is free for startups (https://groups.google.com/d/msg/gremlin-users/kw9N6xYb6l4/uHW23ukWsukJ https://groups.google.com/d/msg/gremlin-users/kw9N6xYb6l4/uH...). There is also a Neo4j Heroku Add On (http://addons.heroku.com/neo4j http://addons.heroku.com/neo4j) that is currently free for developers.
tom_b 15y ago
I have recently been experimenting with Treetop, a ruby gem that allows you to easily work with parsing expression grammars. I may move to Common Lisp or Clojure for writing DSLs, but I am pretty happy with my early experience with Treetop. The one downside, especially compared to Antlr which has a couple of books out there, is that the Treetop documentation had me more than once scratching my head and hacking rather than looking up a relevant reference. I think parsing expression grammars and packrat parsing in general is going to explode the DSL dev scene . . .

andrewcooke 15y ago

interesting, thanks (sorry for misunderstanding slightly). possibly related / useful in future - did you notice that neo4j's licence terms changed a while back? i can't remember the details, but i had avoided it in the past because of licensing and remember that the change seemed to be an improvement.

espeed 15y ago
The Neo4j community edition is now free and licensed under GPL (http://neo4j.org/download/ http://neo4j.org/download/), and they are working on an Enterprise license that is free for startups (https://groups.google.com/d/msg/gremlin-users/kw9N6xYb6l4/uHW23ukWsukJ https://groups.google.com/d/msg/gremlin-users/kw9N6xYb6l4/uH...). There is also a Neo4j Heroku Add On (http://addons.heroku.com/neo4j http://addons.heroku.com/neo4j) that is currently free for developers.

tom_b 15y ago

I have recently been experimenting with Treetop, a ruby gem that allows you to easily work with parsing expression grammars. I may move to Common Lisp or Clojure for writing DSLs, but I am pretty happy with my early experience with Treetop. The one downside, especially compared to Antlr which has a couple of books out there, is that the Treetop documentation had me more than once scratching my head and hacking rather than looking up a relevant reference. I think parsing expression grammars and packrat parsing in general is going to explode the DSL dev scene . . .