Try encoding SML functors in Scala, v2

SMLModules.scala

// A variant of https://gist.github.com/Blaisorblade/19ef1abb28e20995e187, answering
// http://stackoverflow.com/a/23019436/53974
trait ORD {
  type T
  def leq(a: T, b: T): Boolean
}

// The most direct attempt runs into limitations of refinements.
//def F(X : ORD) = new { def eq(x : X.T, y : X.T) = X.leq(x, y) && X.leq(y, x) }
 
// Let's avoid refinements instead by declaring the signature we want — this time without the T member, like in the original
trait EQ[T] {
  def eq(x : T, y : T): Boolean
}

def F(X : ORD) = new EQ[X.T] { def eq(x : X.T, y : X.T) = X.leq(x, y) && X.leq(y, x) }
//F: (X: ORD)EQ[X.T]

Here are the links again, in clickable form. This is a variant of https://gist.github.com/Blaisorblade/19ef1abb28e20995e187, answering http://stackoverflow.com/a/23019436/53974.