case class Field[A](name: String) {
  def ===(value: A): Tree[A] = Equals(this, value)
  def !==(value: A): Tree[A] = NotEquals(this, value)
  def <(value: A): Tree[A] = LessThan(this, value)
  def >(value: A): Tree[A] = GreaterThan(this, value)
  def >=(value: A): Tree[A] = GreaterOrEqual(this, value)
  def <=(value: A): Tree[A] = LessOrEqual(this, value)
}

sealed trait Tree[+A] {
  self =>
  def &&(t: Tree[_]): Tree[_] = and(t)
  def and(t: Tree[_]): Tree[_] = And(self, t)
  def ||(t: Tree[_]): Tree[_] = or(t)
  def or(t: Tree[_]): Tree[_] = Or(self, t)
}
sealed trait Leaf[+A] extends Tree[A] { def field: Field[_]; def value: A }
sealed trait Node[+A] extends Tree[A] { def left: Tree[_]; def right: Tree[_]}
case class Or[+A](left: Tree[_], right: Tree[_]) extends Node[A]
case class And[+A](left: Tree[_], right: Tree[_]) extends Node[A]
case class GreaterOrEqual[A](field: Field[A], value: A) extends Leaf[A]
case class GreaterThan[A](field: Field[A], value: A) extends Leaf[A]
case class LessOrEqual[A](field: Field[A], value: A) extends Leaf[A]
case class LessThan[A](field: Field[A], value: A) extends Leaf[A]
case class Equals[A](field: Field[A], value: A) extends Leaf[A]
case class NotEquals[A](field: Field[A], value: A) extends Leaf[A]

object QueryObjects {
  object Test {
    object name extends Field[String]("name")
    object age extends Field[Int]("age")
    object shoesize extends Field[Int]("shoesize")
    object showsize extends Field[Int]("showsize")
  }
}

(Test.name === "Zandre") and (Test.age > 21) or ((Test.shoesize < 12) and (Test.showsize >= 22))
===
Or(And(Equals(Field(name),Zandre),GreaterThan(Field(age),21)),And(LessThan(Field(shoesize),12),GreaterOrEqual(Field(showsize),22)))

and Test.name === 3 // gives design time error / compile time error