gistfile1.scala

class Ord[T](val lessThan: (T, T) => Boolean)

class Compare[T](x: T)(implicit ord: Ord[T]) {
  def < (that: T) = ord.lessThan(x, that)
  def > (that: T) = ord.lessThan(that, x)
}

implicit def anyToCompare[T: Ord](x: T) = new Compare(x)


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// Note: [T: Ord] is a "context bound" and means there is a T[Ord] in implicit scope
// Usage example: note Foo doesn't extend `Compare`, so can be any existing class

case class Foo(x: String)

implicit val ordFoo: Ord[Foo] = new Ord(_.x.length < _.x.length) 

Foo("abc") < Foo("XY") //false
Foo("abc") > Foo("XY") //true