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InfoQ Homepage Presentations Contravariance is the Dual of Covariance

Contravariance is the Dual of Covariance

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Summary

Erik Meijer introduces covariance and contra-variance with real world examples.

Bio

Erik Meijer is a Dutch computer scientist and entrepreneur. From 2000 to early 2013 he was a software architect for Microsoft where he headed the Cloud Programmability Team. He then founded Applied Duality Inc. in 2013. Before that, he was an associate professor at Utrecht University. He received his Ph.D from Nijmegen University in 1992.

About the conference

Joy of Coding is a one-day conference that celebrates the art, craft, science but foremost the joy of software development. It is a day for talking and collaborating with like-minded coders. The non-profit conference is not targeted towards a particular language or platform.

Recorded at:

Apr 30, 2014

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Community comments

  • Slide errata

    by Srdan Srepfler,

    Your message is awaiting moderation. Thank you for participating in the discussion.

    Can we have the note where the slide are with a bug corrected on the downloadable slides (as additional slide or annotated).
    Thanks.

  • Re: Slide errata

    by Charles Humble,

    Your message is awaiting moderation. Thank you for participating in the discussion.

    Hi Srdan,
    Sorry for the slow response. We can try and get a correction to the slides if needed - do you have a specific example in mind here?

    Charles Humble
    Head of Editorial, InfoQ.com

  • Erik found several mistakes in the slides as he presented

    by Alexander Shopov,

    Your message is awaiting moderation. Thank you for participating in the discussion.

    I don't know which version of slides you have - whether the originals that were presented at the conference or Erik had chance to correct them.

  • Great presentation though a bit agitated

    by Alexander Shopov,

    Your message is awaiting moderation. Thank you for participating in the discussion.

    Erik seemed a bit overwhelmed presenting this but the presentation on covariance/contravariance duality was sweet and kudos to him and the Netflix team for putting this in practice.
    Thanx also for the iterator/yield info for Java.
    Now on to RxJava to check it out...

  • Code from the slides

    by Patrick Di Loreto,

    Your message is awaiting moderation. Thank you for participating in the discussion.

    code contains several mistakes but I will say that the most evident is that the lift method cannot be used for the "Setter"/Observer.

  • make available for download...

    by Gregory Guthrie,

    Your message is awaiting moderation. Thank you for participating in the discussion.

    Please make a better video option available - video + slides.

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