Scalaz's Validations are a fantastic way to handle error checking. We use them pervasively in Myna. The rest of Scalaz I have found less use for, but I think that's due to the domain. I imagine if we had more types of data they would be beneficial.<p>If you've just come to read the comments, be aware that this article is extracted from a more detailed work-in-progress <a href="https://github.com/jrwest/learn_you_a_scalaz" rel="nofollow">https://github.com/jrwest/learn_you_a_scalaz</a> If you have a serious interest in Scalaz you'll be better off reading that.