Custom validation of Configz instances via >=> (Kleisli) operator.

README.md

@@ -15,10 +15,15 @@ val boolPath: Configz[Boolean] = "some.path.to.a.bool".path[Boolean]
 val intPath: Configz[Int] = "some.path.to.an.int".path[Int]
 
 // Get the values at the path, which may fail with a com.typesafe.config.ConfigException.
-val boolProp: ValidationNEL[ConfigException, Boolean] = config.get(boolPath)
-val intProp: ValidationNEL[ConfigException, Int]  = config.get(intPath)
+val boolProp: Settings[Boolean]  = config.get(boolPath)
+val intProp: Settings[Boolean, Int] = config.get(intPath)
 
-// Configz is an applicative functor, so you can combine them (using scalaz operators):
-val boolIntConfig: Configz[(Boolean, Int)] = (boolPath |@| intPath)(_ -> _)
-val boolIntProp: ValidationNEL[ConfigException, (Boolean, Int)] = config.get(boolIntConfig)
+// Note that Settings[A] is an alias for ValidationNEL[ConfigException, A].
+
+// Configz is an applicative functor, so you can combine them (using scalaz operators like <*> or |@|):
+val boolIntConfig: Configz[(Boolean, Int)] = (boolPath |@| intPath)(_ -> _)
+val boolIntProp: Settings[(Boolean, Int)] = config.get(boolIntConfig)
+
+// Configz paths can have custom validation using the >=> (Kleisli) operator:
+val validatedIntPath = intPath >=> validate((_: Int) > 1000, "some.path.to.an.int must be > 1000")
 ```

core/src/main/scala/Configz.scala

@@ -7,10 +7,12 @@ import Scalaz._
 /** Reads settings from a [[com.typesafe.config.Config]]. */
 sealed trait Configz[A] {
  /** Read the settings from a config. */
- def settings(config: Config): ValidationNEL[ConfigException, A]
+ def settings(config: Config): Settings[A]
 }
 
 object Configz {
+ implicit def configzToKleisli[A](configz: Configz[A]): Kleisli[Settings, Config, A] = kleisli(configz.settings)
+
  implicit val ConfigzPure: Pure[Configz] = new Pure[Configz] {
  def pure[A](a: => A): Configz[A] = new Configz[A] {
  def settings(config: Config) =

core/src/main/scala/package.scala

@@ -19,21 +19,36 @@ package net.rosien
  * val boolProp: Settings[Boolean] = config.get(boolPath)
  * val intProp: Settings[Int] = config.get(intPath)
  *
- * // Configz is an applicative functor, so you can combine them:
+ * // Configz is an applicative functor, so you can combine them (using scalaz operators like <*> or |@|):
  * val boolIntConfig: Configz[(Boolean, Int)] = (boolPath |@| intPath)(_ -> _)
- * val boolIntProp: Settings[(Boolean, Int)] = config.get(boolIntProp)
+ * val boolIntProp: Settings[(Boolean, Int)] = config.get(boolIntConfig)
+ *
+ * // Configz paths can have custom validation using the >=> (Kleisli) operator:
+ * val validatedIntPath = intPath >=> validate((_: Int) > 1000, "some.path.to.an.int must be > 1000")
  * }}}
  */
 package object configz {
  import com.typesafe.config._
  import scalaz._
  import Scalaz._
+ import Validation.Monad._
  import Configz._
 
+ type Settings[A] = ValidationNEL[ConfigException, A]
+
+ implicit val SettingsBind = implicitly[Bind[Settings]]
+
+ /** Validate a Configz path.
+ * @param f predicate function
+ * @param message failure message if f returns false
+ * @return validation function to be composed with Configz via >=> operator
+ */
+ def validate[A](f: A => Boolean, message: String): A => Settings[A] = prop =>
+ if (f(prop)) prop.successNel else new ConfigException.Generic(message).failNel[A]
 
  /** Additional methods on [[com.typesafe.config.Config]]. */
  class ConfigOps(config: Config) {
- def get[A](configz: Configz[A]): ValidationNEL[ConfigException, A] = configz.settings(config)
+ def get[A](configz: Kleisli[Settings, Config, A]): ValidationNEL[ConfigException, A] = configz(config)
  }
 
  implicit def configToConfigOps(config: Config): ConfigOps = new ConfigOps(config)

core/src/test/scala/ConfigzSpec.scala

@@ -5,8 +5,9 @@ import org.specs2.scalaz.ValidationMatchers
 
 class ConfigzSpec extends Specification with ValidationMatchers {
  def is = "Configz should" ^
- "accumulate errors" ! configz().errors ^
- "read settings" ! configz().settings ^
+ "accumulate errors" ! configz().errors ^
+ "read settings" ! configz().settings ^
+ "validate via kleisli" ! configz().validateKleisli ^
  end
 
  case class configz() {
@@ -16,6 +17,8 @@ class ConfigzSpec extends Specification with ValidationMatchers {
  import Scalaz._
 
  val config = ConfigFactory.load
+ val boolProp = "configz.bool".path[Boolean]
+ val intProp = "configz.int".path[Int]
 
  def errors = {
  val missing = "configz.asdf".path[String]
@@ -28,12 +31,12 @@ class ConfigzSpec extends Specification with ValidationMatchers {
  }
  }
 
- def settings = {
- val b = "configz.bool".path[Boolean]
- val i = "configz.int".path[Int]
- val bi = b <|*|> i
+ def settings = config.get(boolProp <|*|> intProp) must beSuccessful(true -> 1234)
 
- config.get(bi) must beSuccessful(true -> 1234)
+ def validateKleisli = {
+ val validIntProp = validate((_: Int) < 1000, "configz.int must be < 1000")
+
+ (config.get(intProp >=> validIntProp) must beFailing)
  }
  }
 }