Adds Unwrap method for IResult<TValue>

Author: DrPepperBianco

src/FluentResults/Extensions/ResultExtensions.cs

@@ -336,7 +336,7 @@ public static async Task<Result<TValue>> ToResult<TValue>(this ValueTask<Result>
         #endregion
 
 
-#region Extensions for Task<IResultBase>, ValueTask<IResultBase>, Task<IResult<T>>, and ValueTask<IResult<T>>
+        #region Extensions for Task<IResultBase>, ValueTask<IResultBase>, Task<IResult<T>>, and ValueTask<IResult<T>>
 
 #if false
         public static async Task<IResultBase> MapErrors(this Task<IResultBase> resultTask, Func<IError, IError> errorMapper)

src/FluentResults/Extensions/ResultTValueExtensions.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Linq;
 using System.Collections.Generic;
 using System.Threading.Tasks;
@@ -67,6 +67,39 @@ public static Result<TNewValue> Map<TValue, TNewValue>(this IResult<TValue> resu
                    .WithReasons(result.Reasons);
         }
 
+        /// <summary>
+        /// Unwraps the value of the result.
+        /// </summary>
+        /// <remarks>
+        /// if <paramref name="result"/> is successful, it returns its value, otherwise
+        /// <paramref name="onError"/> is called with the erroneous result.
+        /// </remarks>
+        /// <typeparam name="TValue">
+        /// The underlying type of the result.
+        /// </typeparam>
+        /// <param name="result">
+        /// The result, that is to be unwrapped.
+        /// </param>
+        /// <param name="onError">
+        /// Mapper for the result in case of error. 
+        /// (Could also throw an exception instead.)
+        /// </param>
+        /// <returns>
+        /// Return <c>result.Value</c> if result is successful 
+        /// and the result of the call to <paramref name="onError"/>
+        /// if the result is not successful.
+        /// </returns>
+        static public TValue Unwrap<TValue>(this IResult<TValue> result, Func<IResult<TValue>, TValue> onError)
+        {
+            if(result?.IsSuccess is true)
+            {
+                return result.Value;
+            }
+            else
+            {
+                return onError(result);
+            }
+        }
 
         #region Variants of Bind(), that return result with value