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Erik Osheim: Regexes, Kleene algebras, and real ultimate power!

Summary: If hearing 'regular expression' makes you think of Perl or that Jamie Zawinsky quote, think again! Kleene algebras are a generalization of regular expressions that can be used to compute transitive closure, shortest path, solve linear equations, and more! This talk will explore Kleene algebras, model them in Spire, and go through several concrete examples, with particular attention to regular expressions and languages. We'll see how algebraic properties plus laziness allow an amazingly expressive and powerful implementation.

About the speaker: Erik Osheim is one of the creators of Spire, a Typelevel project designed to support fast, generic, and precise numerical programming in Scala. He is a contributor to the Scala compiler and standard library, and uses Scala to push the limits of JVM performance and expressiveness. Erik works at Meetup, where he collects, processes, and analyzes data to learn how to more effectively create community.

doors & pizza: 6:30pm
talk/Q&A: 6:45pm til 8:00pm or so 
hangout/drinks/food afterwards at Catalyst (on Main at Albany). all are welcome

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  • Cary S.

    One of the best talks I've been to on any programming or software topic in a long time. Kudos!!

    1 · July 14, 2014

  • Bob P.

    Erik, thanks for posting the links to your talk and the code. Very nice presentation!

    2 · July 11, 2014

  • Oliver R.

    That abstract algebra class in grad school was more useful than I thought!

    1 · July 11, 2014

  • Tim

    Very good. Talk was at a high level but great. I think I got about 50% of it which is good. :)

    1 · July 11, 2014

  • Erik O.

    Thanks to everyone who came for being an attentive audience and asking great questions. I had a great time!

    Several people have asked whether the slides are online. There is a PDF available at:

    You can also see the Markdown (and Scala code) I used to build the presentation at:

    The library I'm working on which I referred to in the talk is available here:

    It is a work in progress so please feel free to ask questions, report bugs, and/or send pull requests.

    4 · July 11, 2014

  • Kevin E.

    Excellent. I didn't get all the fine detail but it was a good demonstration of how a simple but powerful base abstraction could be used to solve a quite diverse set of problems in a very clean way. Thanks Erik.

    4 · July 11, 2014

  • Bryce A.

    My new favorite meetup, ever. Erik started with a simple idea: take a few rules, a couple data structures, and a sprinkle of relations, and you've got a simple parser. But wait, thats not all! For only an additional Rig instance, you can find the shortest path on a graph! It slices, it dices...
    Seriously, great meetup. This is the second meetup I've been to that Erik presented, and they have both been fantastic. The slides were well created and presented. We didn't get bogged down in the unimportant details, but there was enough meat to drive the point home.
    And thanks to Akamai for the venue! Great space, and they are very generous for hosting and providing refreshments.

    4 · July 10, 2014

  • A former member
    A former member

    Note that the Clojure meetup is the same night in the same building. No fistfights in the hallways please.

    7 · July 2, 2014

    • Oliver R.

      Don't worry - we're byte code compatible. ;)

      4 · July 9, 2014

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