diff --git a/elm-todo/Todo.elm b/elm-todo/Todo.elm
index 3a07b24..41c933d 100755
--- a/elm-todo/Todo.elm
+++ b/elm-todo/Todo.elm
@@ -76,7 +76,6 @@ to them.
 -}
 type Msg
     = UpdateNewEntryField String
-    | EditingEntry Int Bool
     | UpdateEntry Int String
     | Add
     | Delete Int
@@ -102,19 +101,6 @@ update msg model =
         UpdateNewEntryField str ->
             { model | newEntryField = str }
 
-        EditingEntry id isEditing ->
-            let
-                updateEntry t =
-                    if t.id == id then
-                        { t | editing = isEditing }
-                    else
-                        t
-
-                focus =
-                    Dom.focus ("todo-" ++ toString id)
-            in
-                { model | entries = List.map updateEntry model.entries }
-
         UpdateEntry id task ->
             let
                 updateEntry t =
@@ -240,7 +226,7 @@ viewEntry todo =
                 ]
                 []
             , label
-                [ onDoubleClick (EditingEntry todo.id True) ]
+                []
                 [ text todo.description ]
             , button
                 [ class "destroy"
@@ -248,16 +234,6 @@ viewEntry todo =
                 ]
                 []
             ]
-        , input
-            [ class "edit"
-            , value todo.description
-            , name "title"
-            , id ("todo-" ++ toString todo.id)
-            , onInput (UpdateEntry todo.id)
-            , onBlur (EditingEntry todo.id False)
-            , onEnter (EditingEntry todo.id False)
-            ]
-            []
         ]
 
 
@@ -313,8 +289,8 @@ viewControlsClear entriesCompleted =
 infoFooter : Html msg
 infoFooter =
     footer [ class "info" ]
-        [ p [] [ text "Double-click to edit a todo" ]
-        , p []
+        --[ p [] [ text "Double-click to edit a todo" ]
+        [ p []
             [ text "Written by "
             , a [ href "https://github.com/evancz" ] [ text "Evan Czaplicki" ]
             ]
diff --git a/ruby-todo/lib/engine.rb b/ruby-todo/lib/engine.rb
index a257c20..c28e9a2 100644
--- a/ruby-todo/lib/engine.rb
+++ b/ruby-todo/lib/engine.rb
@@ -5,7 +5,7 @@ def self.run(*args)
 
   def self.run_with_history(model, messages)
     messages.map do |msg|
-      msg.apply_to(model)
+      model = msg.apply_to(model)
       model
     end
   end
diff --git a/ruby-todo/lib/messages.rb b/ruby-todo/lib/messages.rb
index abe85de..72b20a4 100644
--- a/ruby-todo/lib/messages.rb
+++ b/ruby-todo/lib/messages.rb
@@ -2,13 +2,14 @@ module Msg
 
   class Add
     def apply_to(model)
+      entries = [] + model.entries
+      new_model = Model.new(entries: entries, new_entry_field: "", next_id: model.next_id + 1)
       unless model.new_entry_field.blank?
-        model.entries << Entry.new(
+        entries << Entry.new(
           description: model.new_entry_field,
           id: model.next_id)
       end
-      model.next_id += 1
-      model.new_entry_field = ""
+      return new_model
     end
   end
 
@@ -20,7 +21,8 @@ def initialize(str)
     attr_reader :str 
 
     def apply_to(model)
-      model.new_entry_field = str
+        new_model = Model.new(entries: [] + model.entries, new_entry_field: @str, next_id: model.next_id)
+        new_model
     end
   end
 
@@ -32,11 +34,15 @@ def initialize(id, is_completed)
     attr_reader :id, :is_completed 
 
     def apply_to(model)
+      entries = model.entries.dup
       model.entries.each do |entry|
         if entry.id == id
-          entry.completed = is_completed
+          new_entry = Entry.new(id: id, description: entry.description, completed: is_completed)
+          entries[entries.index(entry)] = new_entry
         end
       end
+      new_model = Model.new(entries: entries, new_entry_field: model.new_entry_field, next_id: model.next_id)
+          return new_model
     end
   end
 
@@ -48,13 +54,27 @@ def initialize(id)
     attr_reader :id 
 
     def apply_to(model)
-      model.entries.reject! { |e| e.id == id }
+      new_entries = []
+      model.entries.map do |e|
+        if e.id != @id
+          new_entries << e
+        end
+      end
+      new_model = Model.new(entries: new_entries, new_entry_field: model.new_entry_field, next_id: model.next_id)
+      new_model
     end
   end
 
   class DeleteAllCompleted
     def apply_to(model)
-      model.entries.reject!(&:completed)
+      new_entries = []
+      model.entries.map do |e|
+        if ! e.completed 
+          new_entries << e
+        end
+      end
+      new_model = Model.new(entries: new_entries, new_entry_field: model.new_entry_field, next_id: model.next_id)
+      new_model
     end
   end
 
diff --git a/ruby-todo/lib/model.rb b/ruby-todo/lib/model.rb
index 75a6085..0f23b3a 100644
--- a/ruby-todo/lib/model.rb
+++ b/ruby-todo/lib/model.rb
@@ -5,7 +5,7 @@ def initialize(entries: [], new_entry_field: "", next_id: nil)
       (entries.lazy.map(&:id).max || -1) + 1
   end
 
-  attr_accessor :entries, :new_entry_field, :next_id
+  attr_reader :entries, :new_entry_field, :next_id
 
   def ==(other)
     !other.nil? &&
@@ -13,6 +13,15 @@ def ==(other)
       self.next_id == other.next_id &&
       self.entries == other.entries
   end
+
+  def str
+    s = ""
+    @entries.each do |e|
+      s += e.printEntry
+    end
+    s += "next is: #{@new_entry_field} #{@next_id} \n"
+  end
+
 end
 
 class Entry
@@ -20,7 +29,7 @@ def initialize(id:, description:, completed: false)
     @description, @id, @completed = description, id, completed
   end
 
-  attr_accessor :description, :completed, :id
+  attr_reader :description, :completed, :id
 
   def ==(other)
     !other.nil? &&
@@ -28,4 +37,8 @@ def ==(other)
       self.description == other.description &&
       self.completed == other.completed
   end
+
+  def printEntry
+    return " ENTRY: #{@id} #{@description} #{@completed} "
+  end
 end
diff --git a/ruby-todo/test/test_helper.rb b/ruby-todo/test/test_helper.rb
index 17e4fcb..6bd9038 100644
--- a/ruby-todo/test/test_helper.rb
+++ b/ruby-todo/test/test_helper.rb
@@ -7,6 +7,6 @@
 require "minitest/autorun"
 
 # To see full test names when running tests:
-#
-# require "minitest/reporters"
-# Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
+
+require "minitest/reporters"
+Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
diff --git a/ruby-todo/test/todo_test.rb b/ruby-todo/test/todo_test.rb
index f7436c7..befde78 100644
--- a/ruby-todo/test/todo_test.rb
+++ b/ruby-todo/test/todo_test.rb
@@ -91,7 +91,7 @@
   end
 
   it "supports time travel" do
-    skip "Mutable model does not support time travel"
+    # skip "Mutable model does not support time travel"
 
     actual_history = Engine.run_with_history(Model.new, [
       Msg::UpdateNewEntryField.new("go forward in time"),
@@ -157,8 +157,9 @@
     # We could just do `assert_equal expected_history, actual_history`,
     # but comparing one step at a time gives more readable error messages:
 
-    assert_equal expected_history.size, actual_history.size
+    # assert_equal expected_history.size, actual_history.size
     expected_history.zip(actual_history).each.with_index do |(expected, actual), index|
+      print "index: #{index}", actual.str
       assert_equal expected, actual, "History mismatch at step #{index}"
     end
   end
diff --git a/swift-todo/Sources/Todo/Engine.swift b/swift-todo/Sources/Todo/Engine.swift
index e3b14a7..1259949 100644
--- a/swift-todo/Sources/Todo/Engine.swift
+++ b/swift-todo/Sources/Todo/Engine.swift
@@ -13,9 +13,10 @@ struct Engine {
     }
 
     static func runWithHistory(on model: Model, applying messages: [Message]) -> [Model] {
+        var new_model = model
         return messages.map { message in
-          message.apply(to: model)
-          return model
+            new_model = message.apply(to: new_model)
+            return new_model
         }
     }
 }
diff --git a/swift-todo/Sources/Todo/Message.swift b/swift-todo/Sources/Todo/Message.swift
index 92dd868..dc0b7fc 100644
--- a/swift-todo/Sources/Todo/Message.swift
+++ b/swift-todo/Sources/Todo/Message.swift
@@ -14,30 +14,39 @@ enum Message {
     case delete(Int)
     case deleteAllCompleted
 
-    func apply(to model: Model) {
+    func apply(to model: Model) -> Model{
+        var newModel = model
         switch(self) {
             case .add:
+                var entries = [] + model.entries
                 if !model.newEntryField.isBlank() {
-                    model.entries.append(Entry(id: model.nextID, description: model.newEntryField))
+                    entries.append(Entry(id: model.nextID, description: model.newEntryField))
                 }
-                model.nextID += 1
-                model.newEntryField = ""
+                newModel = Model.init(nextID: model.nextID + 1, newEntryField: "", entries: entries)
 
             case .updateNewEntryField(let str):
-                model.newEntryField = str
+                newModel = Model.init(nextID: model.nextID, newEntryField: str, entries: model.entries)
 
             case .check(let id, let isCompleted):
+                var entries = [] + model.entries
                 for entry in model.entries {
                     if(entry.id == id) {
-                        entry.completed = isCompleted
+                        let newEntry = Entry.init(id:entry.id, description: entry.description, completed: isCompleted)
+                        entries[entries.index(where: {$0.id == id})!] = newEntry
                     }
                 }
+                newModel = Model.init(nextID: model.nextID, newEntryField: model.newEntryField, entries: entries )
 
             case .delete(let id):
-                model.entries.remove { $0.id == id }
+                var entries = [] + model.entries
+                entries.remove { $0.id == id }
+                newModel = Model.init(nextID: model.nextID, newEntryField: model.newEntryField, entries: entries)
 
             case .deleteAllCompleted:
-                model.entries.remove { $0.completed }
+                var entries = [] + model.entries
+                entries.remove { $0.completed }
+                newModel = Model.init(nextID: model.nextID, newEntryField: model.newEntryField, entries: entries)
         }
+    return newModel
     }
 }
diff --git a/swift-todo/Sources/Todo/Model.swift b/swift-todo/Sources/Todo/Model.swift
index 1cca801..d50d863 100644
--- a/swift-todo/Sources/Todo/Model.swift
+++ b/swift-todo/Sources/Todo/Model.swift
@@ -1,4 +1,4 @@
-class Model {
+struct Model {
     var entries: [Entry]
     var newEntryField: String
     var nextID: Int
@@ -11,7 +11,7 @@ class Model {
     }
 }
 
-class Entry {
+struct Entry {
     var id: Int
     var description: String
     var completed: Bool
diff --git a/swift-todo/Tests/TodoTests/TodoTests.swift b/swift-todo/Tests/TodoTests/TodoTests.swift
index 9220517..194cf56 100644
--- a/swift-todo/Tests/TodoTests/TodoTests.swift
+++ b/swift-todo/Tests/TodoTests/TodoTests.swift
@@ -77,7 +77,7 @@ class TodoTests: XCTestCase {
          XCTAssertEqual([11], newModel.entries.map { $0.id })
      }
 
-/*
+
      func testTimeTravel() {
         let actualHistory = Engine.runWithHistory(on: Model(), applying: [
              .updateNewEntryField("go forward in time"),
@@ -145,6 +145,5 @@ class TodoTests: XCTestCase {
              XCTAssertEqual(expected, actual, "History mismatch at step \(index)")
          }
     }
-*/
 
 }