Wouldn't it be so nice if we can do something like (validUserName and validPassword and validCaptcha) thenDo Success where validUserName, validPassword and validCaptcha are functions of type T => Boolean. predicates helps you do exactly that. It provides simple wrapper methods to pimp your T => Boolean functions with and, or and not so that we can write more expressive^[subjective] code.

predicates is published for the following scala versions: 2.11, 2.10, 2.9.3, 2.9.2, 2.9.1.

For Maven

<dependency>
  <groupId>in.ashwanthkumar</groupId>
  <artifactId>predicates_${scala.version}</artifactId>
  <version>0.0.2</version>
</dependency>

For SBT,

libraryDependencies += "in.ashwanthkumar" %% "predicates" % "0.0.2"

I prefer to use predicates while writing data validators.

import in.ashwanthkumar.predicates._

case class Model(id: Int, name: String)

class ModelValidator {
    def hasId = (model: Model) => model.id > 0
    def hasName = (model: Model) => model.name != null && !model.name.isEmpty

    def all = hasId and hasName
    def any = hasId or hasName

    def validate = (all thenDo Success) orElse (not(all) thenDo Failure)
}

$ git clone https://github.com/ashwanthkumar/predicates.git
$ cd predicates
$ sbt test

Apache 2.0