/*
 * Copyright (c) 2013 Miles Sabin 
 *
 * 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 shapeless
package ops

import hlist.Length

object product {
  trait ProductLength[T] extends DepFn1[T]

  object ProductLength {
    type Aux[T, Out0] = ProductLength[T] { type Out = Out0 }
    implicit def length[T, L <: HList]
      (implicit gen: Generic.Aux[T, L], length: Length[L]): Aux[T, length.Out] =
        new ProductLength[T] {
          type Out = length.Out
          def apply(t: T): Out = length()
        }
  }
}