Merging IDOs API

src/DynamicObj/ImmutableDynamicObj.fs

@@ -135,6 +135,12 @@ type ImmutableDynamicObj internal (map : Map<string, obj>) =
                     .ToDictionary((fun (key, _) -> key), fun (_, value) -> value)
         dict
 
+    static member combine (first : 'T when 'T :> ImmutableDynamicObj) (second : ImmutableDynamicObj) =
+        let addProp (ido : 'T) (prop : KeyValuePair<string, obj>) =
+            ido
+            |> ImmutableDynamicObj.add prop.Key prop.Value
+        Seq.fold addProp first second.Properties
+
 
 
 and ImmutableDynamicObjJsonConverter () =

tests/UnitTests/ImmTests.fs

@@ -241,4 +241,19 @@ let ``Json serialization nested`` () =
         ++ ("inner", o2)
     let actual = JsonConvert.SerializeObject o
 
-    Assert.Equal("""{"aaa":5,"hh":[1,2,3],"inner":{"aaa":5,"hh":[1,2,3],"ohno":10,"quack":"tt"},"ohno":10,"quack":"tt"}""", actual)
+    Assert.Equal("""{"aaa":5,"hh":[1,2,3],"inner":{"aaa":5,"hh":[1,2,3],"ohno":10,"quack":"tt"},"ohno":10,"quack":"tt"}""", actual)
+
+[<Fact>]
+let ``Merging two`` () =
+    let a =
+        ImmutableDynamicObj.empty
+        ++ ("aaa", 5)
+        ++ ("bb", 10)
+    let b =
+        ImmutableDynamicObj.empty
+        ++ ("aaa", 11)
+
+    let merged = ImmutableDynamicObj.combine a b
+
+    Assert.Equal(11 :> obj, merged.["aaa"])
+    Assert.Equal(10 :> obj, merged.["bb"])