From c5f1113df8159078ac3bfb6fbe8426db72248512 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=A9my=20Zurcher?= <jeremy@asynk.ch>
Date: Wed, 10 Apr 2013 00:03:54 +0200
Subject: Scala : week2: implement intersect and diff

---
 Scala/funsets/src/main/scala/funsets/FunSets.scala |  4 ++--
 .../src/test/scala/funsets/FunSetSuite.scala       | 24 ++++++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/Scala/funsets/src/main/scala/funsets/FunSets.scala b/Scala/funsets/src/main/scala/funsets/FunSets.scala
index c6d5ea5..1fd2d31 100644
--- a/Scala/funsets/src/main/scala/funsets/FunSets.scala
+++ b/Scala/funsets/src/main/scala/funsets/FunSets.scala
@@ -32,13 +32,13 @@ object FunSets {
    * Returns the intersection of the two given sets,
    * the set of all elements that are both in `s` and `t`.
    */
-  def intersect(s: Set, t: Set): Set = ???
+  def intersect(s: Set, t: Set): Set = (x => s(x) & t(x))
 
   /**
    * Returns the difference of the two given sets,
    * the set of all elements of `s` that are not in `t`.
    */
-  def diff(s: Set, t: Set): Set = ???
+  def diff(s: Set, t: Set): Set = (x => s(x) & !t(x))
 
   /**
    * Returns the subset of `s` for which `p` holds.
diff --git a/Scala/funsets/src/test/scala/funsets/FunSetSuite.scala b/Scala/funsets/src/test/scala/funsets/FunSetSuite.scala
index e61a56c..88dac91 100644
--- a/Scala/funsets/src/test/scala/funsets/FunSetSuite.scala
+++ b/Scala/funsets/src/test/scala/funsets/FunSetSuite.scala
@@ -138,4 +138,28 @@ class FunSetSuite extends FunSuite {
       assert(!contains(s, 3), "Union 3")
     }
   }
+
+  test("intersect") {
+    new TestSets {
+      val s = intersect(s1, s2)
+      assert(!contains(s, 1), "Intersect none")
+      assert(!contains(s, 2), "Intersect none")
+
+      val t = intersect(s1, s1)
+      assert(contains(t, 1), "Intersect 1")
+
+      val v = intersect(s2, s2)
+      assert(contains(v, 2), "Intersect 2")
+    }
+  }
+
+  test("diff") {
+    new TestSets {
+      val s = diff(s1, s2)
+      assert(!contains(s, 0), "Diff none")
+      assert(contains(s, 1), "Diff 1")
+      assert(!contains(s, 2), "Diff none")
+      assert(!contains(s, 3), "Diff none")
+    }
+  }
 }
-- 
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