gistfile1.scala

     
     // Would love to use the following, sadly TypedPipe is not really monadic:
     // * a bind/flatMap operator is missing:
     //   Indeed flatMap currently has the following signature:
     //     def flatMap[U](f: (T) ⇒ TraversableOnce[U]): TypedPipe[U] 
     //   whereas a monadic bind would look like this 
     //    def flatMap[U](f: (T) ⇒  TypedPipe[U]): TypedPipe[U] 
     // * return/unit can be implemented in such way:
     // return[A]: A => TypedPipe[A] = a => TypedPipe.from(List(a))
       for {
        user <- usersPipe
        birthdate <- birthDatesPipe if ( birthDate.userId == user.id )
        present <- presentsPipe if ( present.userId == user.uid )
      } yield ((sale, birthDate, present))