Lift Framework example source code file (HListSpec.scala)

This example Lift Framework source code file (HListSpec.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lift Framework tags/keywords

a, foo, full, full, hlist, hlist, hnil, int, int, left, left, specification, string, yak

The Lift Framework HListSpec.scala source code

/*
 * Copyright 2010-2011 WorldWide Conferencing, LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.liftweb
package common

import org.specs.Specification


/**
 * System under specification for Heterogeneous List.
 */
object HListSpec extends Specification("HList Specification") {

  "An HList" should {

    "get the types right" in {
      import HLists._

      val x = 1 :+: "Foo" :+: HNil

      val head: Int = x.head
      val head2: String = x.tail.head

      x.head must_== 1
      x.tail.head must_== "Foo"
    }
  }

  "A combinable box" should {

    "have a box built with a failure result in a failure" in {
      import CombinableBox._

      val x = Full("a") :&: Full(1) :&: Empty

      // result in a failure
      x match {
        case Left(_) => true must_== true
        case _       => fail("Full elements available")
      }
    }

    "be able to build a box with all the Full elements matching" in {
      import CombinableBox._
      import HLists._

      val x = Full("a") :&: Full(1) :&: Full(List(1,2,3))

      // result in a failure
      x match {
        case Right(a :+: one :+: lst :+:HNil) => {
          // val a2: Int = a  fails... not type safe

          val as: String = a
          val onei: Int = one
          val lstl: List[Int] = lst

          true must_== true
        }
        case Left(_) => fail("Failure elements available")
      }
    }

    "be usable in for comprehension" in {
      import CombinableBox._
      import HLists._

      val res = for {
        a :+: one :+: lst :+: _ <- 
        (Full("a") ?~ "Yak" :&: Full(1) :&: Full(List(1,2,3))) ?~! "Dude"
      } yield a.length * one * lst.foldLeft(1)(_ * _)

      res must_== Full(6)
    }
  }

}