Basic functional vector-based piece movement implementation

src/main/scala/model/Piece.scala

@@ -1,14 +1,27 @@
 package lila
 package model
 
+import scala.annotation.tailrec
+
 case class Piece(color: Color, role: Role) {
 
+  type Vector = Pos ⇒ Option[Pos]
+
   def basicMoves(pos: Pos, board: Board): Set[Pos] = {
 
     role match {
       case Rook ⇒ {
-        val vectors: List[Pos => Option[Pos]] = List(_.up, _.down, _.left, _.right)
-        Set.empty
+        val occupation = board occupation !color
+        val vectors: List[Vector] = List(_.up, _.down, _.left, _.right)
+
+        //@tailrec
+        def fwd(p: Pos, v: Vector): List[Pos] = v(p) map { next ⇒
+          next :: fwd(next, v)
+        } getOrElse Nil
+
+        vectors flatMap { vector =>
+          fwd(pos, vector)
+        } toSet
       }
       case _ ⇒ Set.empty
     }

src/main/scala/model/Pos.scala

@@ -3,7 +3,7 @@ package model
 
 import scala.math.{ abs, min, max }
 
-case class Pos private(x: Int, y: Int) {
+case class Pos private(x: Int, y: Int) extends Ordered[Pos] {
 
   import Pos.pos
 
@@ -31,6 +31,8 @@ case class Pos private(x: Int, y: Int) {
 
   override def toString = xToString + yToString
 
+  def compare(other: Pos) = toString compare other.toString
+
   private def expand(i: Int, accumulator: List[Option[Pos]], direct: Option[Pos] ⇒ Option[Pos]): List[Option[Pos]] = {
     if (i > 0 && accumulator.head.isDefined)
       expand(i - 1, direct(accumulator.head) :: accumulator, direct)

src/test/scala/LilaSpec.scala

@@ -10,7 +10,7 @@ trait LilaSpec
     extends Specification
     with OrnicarValidationMatchers {
 
-  def bePoss(poss: Pos*): Matcher[Valid[Set[Pos]]] = beSuccess.like {
-    case p ⇒ p.toSet must_== poss
+  def bePoss(poss: Pos*): Matcher[Valid[Iterable[Pos]]] = beSuccess.like {
+    case p ⇒ p.toList.sorted must_== poss.toList.sorted
   }
 }