Making sense of Play Iteratees, Enumerators, and Enumeratees

  • May 23, 2013 · 7:00 PM
  • This location is shown only to members

Nicolas Leroux from the Play team and some of his colleagues at Lunatech (Erik and/or Peter) will help us demystify Play Iteratees, Enumerators, and Enumeratees.


18:30 - 19:30: food and drinks

19:30 - 20:30: Iteratees explained by Nicolas and Peter

20:30 - 21:30: Discussion and open mike: ask anything


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  • David S.

    Was very educational :-) Thanks!

    May 25, 2013

  • Thierry de K.

    Thanks for the interesting talk! I also enjoyed the "open mic" parts. Sounds like a kickass Christmas!

    May 24, 2013

  • Erik B.

    Generally an Enumerator won't push an EOF, because that would finish off the Iteratee and maybe you want to push more stuff into the Iteratee.

    But theres `Enumerator.eof`, which is an Enumerator that only sends an EOF. So you could compose your Enumerators as:

    Enumerator(1,2,3,4) andThen Enumerator.EOF

    Or if you like operators:

    Enumerator(1,2,3,4) >>> Enumerator.EOF

    Since it's pretty common to do this, there's an alternative way:

    Enumerator(1,2,3,4) run iteratee

    Where the 'apply' method on an Enumerator just pushes all chunks and returns the new iteratee, the 'run' method does that first, then sends an EOF and then extracts the result.

    If you like operators:

    Enumerator(1,2,3,4) |>>>> summingIteratee

    This will return Future[Int] which will contain '10', for the obvious implementation of 'summingIteratee'.

    May 24, 2013

  • Jan-Pieter van den H.

    Great meetup! Love the fish operator ;) One question: when you push elements in an enumerator, do you have to push EOF yourself or does it automatically get in if all elements are consumed?

    May 24, 2013

  • Giorgio

    Thanks again guys, amazing presentation. I still feel the need to double check the example but for sure I understand now much more about it!!

    May 24, 2013

  • Guus B.

    Skipped dinner, was late anyway but it was worth it. Very interesting!

    May 24, 2013

  • Erik B.

    The 'iteratees by example' can be found here:

    This is a 'Worksheet' from Scala IDE. The comments that are aligned to the right are the output.

    To play with it, save with '.sc' extension and open with Eclipse and a recent Scala-IDE installed.

    The Video demo source is located here:

    May 23, 2013

  • Joost H.

    Learned and had fun

    1 · May 23, 2013

  • Ievgen M.

    Sorry missed because of meeting till 8:30

    May 23, 2013

  • Gordon C.

    Could not make it because of work.

    May 23, 2013

  • Guus B.

    I will be latew

    May 23, 2013

  • Ender A.

    being sick. hope next time being there

    May 23, 2013

  • A former member
    A former member

    Presenting with Nicolas

    May 23, 2013

  • Alexander L.

    injured my back :-(

    May 23, 2013

  • Joost H.

    Looking forward to the talks!

    May 22, 2013

  • Age M.

    Thanks to Elmar (the person, not the company), we now have a location! Thanks Elmar and thanks Rockstart Accelerator!

    May 16, 2013

  • Age M.

    Hi All. I'm still working on arranging a location in Amsterdam. I expect to know more by the end of today (Thursday 17/5) or at the very latest tomorrow (Friday 18/5).

    May 16, 2013

  • Roy P.

    Rhinofly (Utrecht) would like to offer a free location and drinks for the meeting 23 May.

    1 · April 22, 2013

    • Age M.

      Hmmm, I greatly appreciate your offer but would you mind if I search for just a bit longer to see whether we can find a a location that is easier to reach (by public transport) for most of our members? My experience with these things tells me that it greatly decreases the number of people who will show up. I will try to get back to you within the next week.

      April 23, 2013

    • Roy P.

      No problem

      April 23, 2013

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