Add bi-conditional <-->

(cherry picked from commit 3896a3e)
scalaz · Sep 16, 2015 · 27c9821 · 27c9821
1 parent 3ab9071
commit 27c9821
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diff --git a/core/src/main/scala/scalaz/syntax/std/BooleanOps.scala b/core/src/main/scala/scalaz/syntax/std/BooleanOps.scala
@@ -126,6 +126,19 @@ final class BooleanOps(self: Boolean) {
    */
   final def <--(q: => Boolean) = b.inverseConditional(self, q)
 
+  /**
+   * Bi-Conditional.
+   *
+   * {{{
+   * p q  p <--> q
+   * 0 0  1
+   * 0 1  0
+   * 1 0  0
+   * 1 1  1
+   * }}}
+   */
+  final def <-->(q: => Boolean) = b.conditional(self, q) && b.inverseConditional(self, q)
+
   /**
    * Inverse Conditional.
    *

diff --git a/tests/src/test/scala/scalaz/BooleanSyntaxTest.scala b/tests/src/test/scala/scalaz/BooleanSyntaxTest.scala
@@ -31,6 +31,13 @@ object BooleanSyntaxTest extends SpecLite {
       p <-- q == (p || !q)
     }
 
+    "bi-conditional" in {
+      assert(false <--> false)
+      assert(true <--> true)
+      assert(!(true <--> false))
+      assert(!(false <--> true))
+    }
+
     "negate conditional" ! forAll { (p:Boolean, q:Boolean) =>
       p -/> q == (p && !q)
     }