Data commit

Task/Monads-Maybe-monad/C-sharp/monads-maybe-monad.cs

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+using System;
+
+namespace RosettaMaybe
+{
+    // courtesy of https://www.dotnetcurry.com/patterns-practices/1510/maybe-monad-csharp
+    public abstract class Maybe<T>
+    {
+        public sealed class Some : Maybe<T>
+        {
+            public Some(T value) => Value = value;
+            public T Value { get; }
+        }
+        public sealed class None : Maybe<T> { }
+    }
+
+    class Program
+    {
+        static Maybe<double> MonadicSquareRoot(double x)
+        {
+            if (x >= 0)
+            {
+                return new Maybe<double>.Some(Math.Sqrt(x));
+            }
+            else
+            {
+                return new Maybe<double>.None();
+            }
+        }
+        static void Main(string[] args)
+        {
+            foreach (double x in new double[] { 4.0D, 8.0D, -15.0D, 16.23D, -42 })
+            {
+                Maybe<double> maybe = MonadicSquareRoot(x);
+                if (maybe is Maybe<double>.Some some)
+                {
+                    Console.WriteLine($"The square root of {x} is " + some.Value);
+                }
+                else
+                {
+                    Console.WriteLine($"Square root of {x} is undefined.");
+                }
+            }
+        }
+    }
+}