Data commit

Task/Ternary-logic/C-sharp/ternary-logic.cs

@@ -0,0 +1,45 @@
+using System;
+
+/// <summary>
+/// Extension methods on nullable bool.
+/// </summary>
+/// <remarks>
+/// The operators !, & and | are predefined.
+/// </remarks>
+public static class NullableBoolExtension
+{
+    public static bool? Implies(this bool? left, bool? right)
+    {
+        return !left | right;
+    }
+
+    public static bool? IsEquivalentTo(this bool? left, bool? right)
+    {
+        return left.HasValue && right.HasValue ? left == right : default(bool?);
+    }
+
+    public static string Format(this bool? value)
+    {
+        return value.HasValue ? value.Value.ToString() : "Maybe";
+    }
+}
+
+public class Program
+{
+    private static void Main()
+    {
+        var values = new[] { true, default(bool?), false };
+
+        foreach (var left in values)
+        {
+            Console.WriteLine("¬{0} = {1}", left.Format(), (!left).Format());
+            foreach (var right in values)
+            {
+                Console.WriteLine("{0} & {1} = {2}", left.Format(), right.Format(), (left & right).Format());
+                Console.WriteLine("{0} | {1} = {2}", left.Format(), right.Format(), (left | right).Format());
+                Console.WriteLine("{0} → {1} = {2}", left.Format(), right.Format(), left.Implies(right).Format());
+                Console.WriteLine("{0} ≡ {1} = {2}", left.Format(), right.Format(), left.IsEquivalentTo(right).Format());
+            }
+        }
+    }
+}