--- a/Implab/PromiseExtensions.cs	Tue Jan 30 01:37:17 2018 +0300
+++ b/Implab/PromiseExtensions.cs	Wed Jan 31 11:28:38 2018 +0300
@@ -8,97 +8,145 @@
     public static class PromiseExtensions {
 
         public static IPromise Then(this IPromise that, Action fulfilled, Action<Exception> rejected) {
-            var reaction = new PromiseActionReaction(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseActionReaction.Create(fulfilled, rejected, Promise.DefaultDispatcher);
+            that.Then(reaction);
+            return reaction.Promise;
+        }
+
+        public static IPromise Then(this IPromise that, Action fulfilled) {
+            var reaction = PromiseActionReaction.Create(fulfilled, null, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise Then(this IPromise that, Action fulfilled, Func<Exception, IPromise> rejected) {
-            var reaction = new PromiseActionReaction(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseActionReaction.Create(fulfilled, rejected, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise Then(this IPromise that, Func<IPromise> fulfilled, Action<Exception> rejected) {
-            var reaction = new PromiseActionReaction(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseActionReaction.Create(fulfilled, rejected, Promise.DefaultDispatcher);
+            that.Then(reaction);
+            return reaction.Promise;
+        }
+
+        public static IPromise Then(this IPromise that, Func<IPromise> fulfilled) {
+            var reaction = PromiseActionReaction.Create(fulfilled, null, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise Then(this IPromise that, Func<IPromise> fulfilled, Func<Exception, IPromise> rejected) {
-            var reaction = new PromiseActionReaction(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseActionReaction.Create(fulfilled, rejected, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise Then<T>(this IPromise<T> that, Action<T> fulfilled, Action<Exception> rejected) {
-            var reaction = new PromiseActionReaction<T>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseActionReaction<T>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
+            that.Then(reaction);
+            return reaction.Promise;
+        }
+
+        public static IPromise Then<T>(this IPromise<T> that, Action<T> fulfilled) {
+            var reaction = PromiseActionReaction<T>.Create(fulfilled, null, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise Then<T>(this IPromise<T> that, Action<T> fulfilled, Func<Exception, IPromise> rejected) {
-            var reaction = new PromiseActionReaction<T>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseActionReaction<T>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise Then<T>(this IPromise<T> that, Func<T, IPromise> fulfilled, Action<Exception> rejected) {
-            var reaction = new PromiseActionReaction<T>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseActionReaction<T>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
+            that.Then(reaction);
+            return reaction.Promise;
+        }
+
+        public static IPromise Then<T>(this IPromise<T> that, Func<T, IPromise> fulfilled) {
+            var reaction = PromiseActionReaction<T>.Create(fulfilled, null, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise Then<T>(this IPromise<T> that, Func<T, IPromise> fulfilled, Func<Exception, IPromise> rejected) {
-            var reaction = new PromiseActionReaction<T>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseActionReaction<T>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise<Tout> Then<Tout>(this IPromise that, Func<Tout> fulfilled, Func<Exception, Tout> rejected) {
-            var reaction = new PromiseFuncReaction<Tout>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseFuncReaction<Tout>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
+            that.Then(reaction);
+            return reaction.Promise;
+        }
+
+        public static IPromise<Tout> Then<Tout>(this IPromise that, Func<Tout> fulfilled) {
+            var reaction = PromiseFuncReaction<Tout>.Create(fulfilled, (Func<Exception, Tout>)null, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise<Tout> Then<Tout>(this IPromise that, Func<Tout> fulfilled, Func<Exception, IPromise<Tout>> rejected) {
-            var reaction = new PromiseFuncReaction<Tout>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseFuncReaction<Tout>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise<Tout> Then<Tout>(this IPromise that, Func<IPromise<Tout>> fulfilled, Func<Exception, Tout> rejected) {
-            var reaction = new PromiseFuncReaction<Tout>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseFuncReaction<Tout>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
+            that.Then(reaction);
+            return reaction.Promise;
+        }
+
+        public static IPromise<Tout> Then<Tout>(this IPromise that, Func<IPromise<Tout>> fulfilled) {
+            var reaction = PromiseFuncReaction<Tout>.Create(fulfilled, (Func<Exception, Tout>)null, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise<Tout> Then<Tout>(this IPromise that, Func<IPromise<Tout>> fulfilled, Func<Exception, IPromise<Tout>> rejected) {
-            var reaction = new PromiseFuncReaction<Tout>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseFuncReaction<Tout>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise<Tout> Then<Tin, Tout>(this IPromise<Tin> that, Func<Tin, Tout> fulfilled, Func<Exception, Tout> rejected) {
-            var reaction = new PromiseFuncReaction<Tin, Tout>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseFuncReaction<Tin, Tout>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
+            that.Then(reaction);
+            return reaction.Promise;
+        }
+
+        public static IPromise<Tout> Then<Tin, Tout>(this IPromise<Tin> that, Func<Tin, Tout> fulfilled) {
+            var reaction = PromiseFuncReaction<Tin, Tout>.Create(fulfilled, (Func<Exception, Tout>)null, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise<Tout> Then<Tin, Tout>(this IPromise<Tin> that, Func<Tin, Tout> fulfilled, Func<Exception, IPromise<Tout>> rejected) {
-            var reaction = new PromiseFuncReaction<Tin, Tout>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseFuncReaction<Tin, Tout>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise<Tout> Then<Tin, Tout>(this IPromise<Tin> that, Func<Tin, IPromise<Tout>> fulfilled, Func<Exception, Tout> rejected) {
-            var reaction = new PromiseFuncReaction<Tin, Tout>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseFuncReaction<Tin, Tout>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
+            that.Then(reaction);
+            return reaction.Promise;
+        }
+
+        public static IPromise<Tout> Then<Tin, Tout>(this IPromise<Tin> that, Func<Tin, IPromise<Tout>> fulfilled) {
+            var reaction = PromiseFuncReaction<Tin, Tout>.Create(fulfilled, (Func<Exception, Tout>)null, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
 
         public static IPromise<Tout> Then<Tin, Tout>(this IPromise<Tin> that, Func<Tin, IPromise<Tout>> fulfilled, Func<Exception, IPromise<Tout>> rejected) {
-            var reaction = new PromiseFuncReaction<Tin, Tout>(fulfilled, rejected, Promise.DefaultDispatcher);
+            var reaction = PromiseFuncReaction<Tin, Tout>.Create(fulfilled, rejected, Promise.DefaultDispatcher);
             that.Then(reaction);
             return reaction.Promise;
         }
@@ -126,6 +174,44 @@
         public static IPromise<Tout> Catch<Tin, Tout>(this IPromise<Tin> that, Func<Exception, IPromise<Tout>> rejected) {
             return Then(that, (Func<Tin, Tout>)null, rejected);
         }
+
+        public static IPromise Finally(this IPromise that, Action final) {
+            return Then(that, final, e => {
+                final();
+                throw e.Rethrow();
+            });
+        }
+
+        public static IPromise Finally(this IPromise that, Func<IPromise> final) {
+            return Then(that, final, e => {
+                final();
+                throw e.Rethrow();
+            });
+        }
+
+        public static IPromise<T> Finally<T>(this IPromise<T> that, Action final) {
+            return Then<T, T>(that, x => {
+                final();
+                return x;
+            }, new Func<Exception, T>(e => {
+                final();
+                throw e.Rethrow();
+            }));
+        }
+
+        public static IPromise<T> Finally<T>(this IPromise<T> that, Func<IPromise> final) {
+            return Then<T, T>(that, x => {
+                return final()
+                    .Then(() => x);
+            }, new Func<Exception, IPromise<T>>(e => {
+                return final()
+                    .Then(new Func<T>(() => {
+                        throw e.Rethrow();
+                    }));
+            }));
+        }
+
+
     }
 }