private FrButton(DiscreteCell <string> label, StreamLoop <Unit> sClicked)
: base((size, sMouse, sKey, focus, idSupply) =>
{
Stream <Unit> sPressed = sMouse.Snapshot(size,
(e, mSize) => mSize.Match(
s =>
{
MouseButtonEventArgs b = e.Args as MouseButtonEventArgs;
Point p = e.GetPosition();
return(b != null && b.ChangedButton == MouseButton.Left && b.ButtonState == MouseButtonState.Pressed &&
p.X >= 2 && p.X < s.Width - 2 && p.Y >= 2 && p.Y < s.Height - 2
? Maybe.Just(Unit.Value)
: Maybe.Nothing <Unit>());
},
Maybe.Nothing <Unit>)).FilterMaybe();
Stream <Unit> sReleased = sMouse.Snapshot(size,
(e, mSize) => mSize.Match(
s =>
{
MouseButtonEventArgs b = e.Args as MouseButtonEventArgs;
return(b != null && b.ChangedButton == MouseButton.Left && b.ButtonState == MouseButtonState.Released
? Maybe.Just(Unit.Value)
: Maybe.Nothing <Unit>());
},
Maybe.Nothing <Unit>)).FilterMaybe();
DiscreteCell <bool> pressed = sPressed.MapTo(true).OrElse(sReleased.MapTo(false)).Hold(false);
sClicked.Loop(sReleased.Gate(pressed));
Typeface typeface = new Typeface(new FontFamily("Helvetica"), FontStyles.Normal, FontWeights.Normal, FontStretches.Normal);
DiscreteCell <Size> desiredSize = label.Map(l =>
{
Size labelSize = FontUtilities.MeasureString(l, typeface, 13);
return(new Size(labelSize.Width + 14, labelSize.Height + 10));
});
return(new Output(
label.Lift(
size, pressed,
(l, mSize, p) => new DrawableDelegate(d =>
{
mSize.Match(sz =>
{
d.DrawRectangle(p ? Brushes.DarkGray : Brushes.LightGray, new Pen(Brushes.Black, 1), new Rect(new Point(2, 2), new Size(sz.Width - 5, sz.Height - 5)));
FormattedText t = FontUtilities.GetStandardFormattedText(l, typeface, 13, Brushes.Black);
d.DrawText(t, new Point((sz.Width - t.Width) / 2, (sz.Height - t.Height) / 2));
}, () => { });
})),
desiredSize,
Stream.Never <long>()));
})
{
this.SClicked = sClicked;
}
public SLabel(DiscreteCell <string> text)
{
Action <string> setText = t => this.Dispatcher.InvokeIfNecessary(() => this.Text = t);
// Set the initial value at the end of the transaction so it works with CellLoops.
Transaction.Post(() => setText(text.Cell.Sample()));
// ReSharper disable once UseObjectOrCollectionInitializer
List <IListener> listeners = new List <IListener>();
listeners.Add(text.Updates.Listen(setText));
this.listeners = listeners;
}
public void TestLiftSimultaneousUpdates()
{
List <int> @out = new List <int>();
DiscreteCellSink <int> cellSink = DiscreteCell.CreateSink(1);
DiscreteCell <int> cell = cellSink.Map(v => 2 * v);
IListener l = cellSink.Lift(cell, (x, y) => x + y).Updates.Listen(@out.Add);
cellSink.Send(2);
cellSink.Send(7);
l.Unlisten();
CollectionAssert.AreEqual(new[] { 6, 21 }, @out);
}
public void Post()
{
DiscreteCell <int> cell = Transaction.Run(() =>
{
StreamSink <int> s = Stream.CreateSink <int>();
s.Send(2);
return(s.Hold(1));
});
int value = 0;
Transaction.Post(() => value = cell.Cell.Sample());
Assert.AreEqual(value, 2);
}
public static DiscreteCell <double> Accumulate(
Stream <Unit> sClearAccumulator,
Stream <int> sPulses,
DiscreteCell <double> calibration)
{
DiscreteCellLoop <int> total = new DiscreteCellLoop <int>();
total.Loop(sClearAccumulator.Map(u => 0)
.OrElse(sPulses.Snapshot(total, (pulsesLocal, totalLocal) => pulsesLocal + totalLocal))
.Hold(0));
return(total.Lift(
calibration,
(totalLocal, calibrationLocal) => totalLocal * calibrationLocal));
}
public void TestDiscreteCellValuesThenLateListen()
{
DiscreteCellSink <int> c = DiscreteCell.CreateSink(9);
List <int> @out = new List <int>();
Stream <int> value = c.Values;
c.Send(8);
IListener l = value.Listen(@out.Add);
c.Send(2);
c.Send(7);
l.Unlisten();
CollectionAssert.AreEqual(new[] { 2, 7 }, @out);
}
public SComboBox(Stream <IMaybe <T> > setSelectedItem, IMaybe <T> initSelectedItem, IEnumerable <T> items)
{
Action <IMaybe <T> > setSelectedItemImpl = m => base.SelectedItem = m.Match <object>(v => v, () => null);
this.ItemsSource = items ?? new T[0];
setSelectedItemImpl(initSelectedItem);
List <IListener> listeners = new List <IListener>();
StreamSink <int> sDecrement = new StreamSink <int>();
DiscreteCell <bool> allow = setSelectedItem.Map(_ => 1).OrElse(sDecrement).Accum(0, (b, d) => b + d).Map(b => b == 0);
Func <IMaybe <T> > getSelectedItem = () =>
{
object sel = base.SelectedItem;
return(sel == null?Maybe.Nothing <T>() : Maybe.Just((T)sel));
};
StreamSink <IMaybe <T> > sUserSelectedItem = new StreamSink <IMaybe <T> >();
this.SUserSelectedItem = sUserSelectedItem;
this.SelectedItem = sUserSelectedItem.Gate(allow).OrElse(setSelectedItem).Hold(initSelectedItem);
SelectionChangedEventHandler selectionChangedEventHandler = (sender, args) =>
{
IMaybe <T> selectedItem = getSelectedItem();
this.Dispatcher.InvokeAsync(() => sUserSelectedItem.Send(selectedItem));
};
this.SelectionChanged += selectionChangedEventHandler;
listeners.Add(setSelectedItem.Listen(m =>
{
this.Dispatcher.InvokeAsync(() =>
{
this.SelectionChanged -= selectionChangedEventHandler;
setSelectedItemImpl(m);
this.SelectionChanged += selectionChangedEventHandler;
sDecrement.Send(-1);
});
}));
this.disposeListeners = () =>
{
foreach (IListener l in listeners)
{
l.Unlisten();
}
};
}
public static DiscreteCell <double> CapturePrice(
Stream <Fuel> sStart,
DiscreteCell <double> price1, DiscreteCell <double> price2,
DiscreteCell <double> price3)
{
Stream <double> sPrice1 = sStart.Snapshot(price1,
(f, p) => f == Fuel.One ? Maybe.Some(p) : Maybe.None).FilterMaybe();
Stream <double> sPrice2 = sStart.Snapshot(price2,
(f, p) => f == Fuel.Two ? Maybe.Some(p) : Maybe.None).FilterMaybe();
Stream <double> sPrice3 = sStart.Snapshot(price3,
(f, p) => f == Fuel.Three ? Maybe.Some(p) : Maybe.None).FilterMaybe();
return(sPrice1.OrElse(sPrice2.OrElse(sPrice3)).Hold(0.0));
}
public void TestAccum()
{
StreamSink <int> sa = Stream.CreateSink <int>();
List <int> @out = new List <int>();
DiscreteCell <int> sum = sa.Accum(100, (a, s) => a + s);
IListener l = sum.Listen(@out.Add);
sa.Send(5);
sa.Send(7);
sa.Send(1);
sa.Send(2);
sa.Send(3);
l.Unlisten();
CollectionAssert.AreEqual(new[] { 100, 105, 112, 113, 115, 118 }, @out);
}
public MainWindow()
{
this.InitializeComponent();
this.Container.Children.Add(Transaction.Run(() =>
{
FrButton ok = new FrButton(DiscreteCell.Constant("OK"));
FrButton cancel = new FrButton(DiscreteCell.Constant("Cancel"));
IReadOnlyList <Fridget> fridgets = new[] { ok, cancel };
Fridget dialog = new FrFlow(Orientation.Horizontal, fridgets);
IListener lOk = ok.SClicked.Listen(_ => this.AddMessage("OK"));
IListener lCancel = cancel.SClicked.Listen(_ => this.AddMessage("Cancel"));
return(new FrView(this, dialog, new CompositeListener(new[] { lOk, lCancel })));
}));
}
public void TestCalm2()
{
DiscreteCellSink <int> c = DiscreteCell.CreateSink(2);
List <int> @out = new List <int>();
IListener l = Transaction.Run(() => c.Calm().Listen(@out.Add));
c.Send(4);
c.Send(2);
c.Send(4);
c.Send(4);
c.Send(2);
c.Send(2);
l.Unlisten();
CollectionAssert.AreEqual(new[] { 2, 4, 2, 4, 2 }, @out);
}
public void PostInTransaction()
{
int value = 0;
Transaction.RunVoid(() =>
{
StreamSink <int> s = Stream.CreateSink <int>();
s.Send(2);
DiscreteCell <int> c = s.Hold(1);
Transaction.Post(() => value = c.Cell.Sample());
Assert.AreEqual(value, 0);
});
Assert.AreEqual(value, 2);
}
public MainWindow()
{
this.InitializeComponent();
SDateField dep = new SDateField();
SDateField ret = new SDateField();
DiscreteCell <bool> valid = dep.SelectedDate.Lift(ret.SelectedDate, (d, r) => d <= r);
SButton ok = new SButton(valid)
{
Content = "OK", Width = 75
};
this.DeparturePlaceholder.Children.Add(dep);
this.ReturnPlaceholder.Children.Add(ret);
this.ButtonPlaceholder.Children.Add(ok);
}
public SButton(DiscreteCell <bool> enabled)
{
StreamSink <Unit> sClickedSink = new StreamSink <Unit>();
this.SClicked = sClickedSink;
this.Click += (sender, args) => sClickedSink.Send(Unit.Value);
// Set the initial value at the end of the transaction so it works with CellLoops.
Transaction.Post(() => this.IsEnabled = enabled.Cell.Sample());
// ReSharper disable once UseObjectOrCollectionInitializer
List <IListener> listeners = new List <IListener>();
listeners.Add(enabled.Updates.Listen(e => this.Dispatcher.InvokeIfNecessary(() => this.IsEnabled = e)));
this.listeners = listeners;
}
public STextBox(Stream <string> setText, string initText, DiscreteCell <bool> enabled)
{
base.Text = initText;
List <IListener> listeners = new List <IListener>();
StreamSink <int> sDecrement = new StreamSink <int>();
DiscreteCell <bool> allow = setText.Map(_ => 1).OrElse(sDecrement).Accum(0, (b, d) => b + d).Map(b => b == 0);
StreamSink <string> sUserChanges = new StreamSink <string>();
this.SUserChanges = sUserChanges;
this.Text = sUserChanges.Gate(allow).OrElse(setText).Hold(initText);
void TextChangedEventHandler(object sender, TextChangedEventArgs args)
{
string text = base.Text;
this.Dispatcher.InvokeAsync(() => sUserChanges.Send(text));
}
this.TextChanged += TextChangedEventHandler;
// Set the initial value at the end of the transaction so it works with CellLoops.
Transaction.Post(() => this.Dispatcher.InvokeIfNecessary(() => this.IsEnabled = enabled.Cell.Sample()));
listeners.Add(setText.Listen(t =>
{
this.Dispatcher.InvokeAsync(() =>
{
this.TextChanged -= TextChangedEventHandler;
base.Text = t;
this.TextChanged += TextChangedEventHandler;
sDecrement.Send(-1);
});
}));
listeners.Add(enabled.Updates.Listen(e => this.Dispatcher.InvokeIfNecessary(() => this.IsEnabled = e)));
this.disposeListeners = () =>
{
foreach (IListener l in listeners)
{
l.Unlisten();
}
};
}
public Frp(Action <string> addMessage)
{
this.listener = Transaction.Run(() =>
{
DiscreteCell <Maybe <DragInfo> > dragInfo =
this.sMouseDown.Map(me => Maybe.Some(new DragInfo(me, Canvas.GetLeft(me.Element.Polygon).ZeroIfNaN(), Canvas.GetTop(me.Element.Polygon).ZeroIfNaN())))
.OrElse(this.sMouseUp.Map(_ => Maybe <DragInfo> .None)).Hold(Maybe.None);
Stream <MouseEvt> mouseMoveWhileDragging = dragInfo.Map(md => md.Match(d => this.sMouseMove, Stream.Never <MouseEvt>)).SwitchS();
IListener listener1 = dragInfo.Values.FilterMaybe().Listen(d => addMessage("FRP dragging " + d.Me.Element.Name));
IListener listener2 = mouseMoveWhileDragging.Snapshot(dragInfo, (me, md) => md.Match(d => Maybe.Some(new Reposition(d, me)), () => Maybe.None)).FilterMaybe().Listen(p =>
{
Canvas.SetLeft(p.Polygon, p.Left);
Canvas.SetTop(p.Polygon, p.Top);
});
return(new CompositeListener(new[] { listener1, listener2 }));
});
}
public MainWindow()
{
this.InitializeComponent();
STextBox english = new STextBox("I like FRP")
{
Width = 150
};
this.TextBoxPlaceholder.Children.Add(english);
Stream <string> sLatin = this.TranslateButton.SClicked.Snapshot(english.Text, (u, t) => Regex.Replace(t.Trim(), " |$", "us "));
DiscreteCell <string> latin = sLatin.Hold(string.Empty);
SLabel lblLatin = new SLabel(latin);
this.TextPlaceholder.Children.Add(lblLatin);
}
public void Test_Snapshot_TestCase()
{
Tuple <Stream <char>, Dictionary <int, Action> > s1T = MkStream(new Dictionary <int, char> {
{ 0, 'a' }, { 3, 'b' }, { 5, 'c' }
});
Stream <char> s1 = s1T.Item1;
Dictionary <int, Action> s1F = s1T.Item2;
Tuple <Stream <int>, Dictionary <int, Action> > s2T = MkStream(new Dictionary <int, int> {
{ 1, 4 }, { 5, 7 }
});
Stream <int> s2 = s2T.Item1;
Dictionary <int, Action> s2F = s2T.Item2;
DiscreteCell <int> c = s2.Hold(3);
List <int> @out = RunSimulation <int>(s1.Snapshot(c.Cell).Listen, new[] { s1F, s2F });
CollectionAssert.AreEqual(new[] { 3, 4, 4 }, @out);
}
public void TestLiftFromSimultaneous()
{
ValueTuple <DiscreteCellSink <int>, DiscreteCellSink <int> > t = Transaction.Run(() =>
{
DiscreteCellSink <int> localC1 = DiscreteCell.CreateSink(3);
DiscreteCellSink <int> localC2 = DiscreteCell.CreateSink(5);
localC2.Send(7);
return(ValueTuple.Create(localC1, localC2));
});
DiscreteCellSink <int> c1 = t.Item1;
DiscreteCellSink <int> c2 = t.Item2;
List <int> @out = new List <int>();
IListener l = c1.Lift(c2, (x, y) => x + y).Listen(@out.Add);
l.Unlisten();
CollectionAssert.AreEqual(new[] { 10 }, @out);
}
public MainWindow()
{
this.InitializeComponent();
STextBox msg = new STextBox("Hello")
{
Width = 150
};
DiscreteCell <string> reversed = msg.Text.Map(t => new string(t.Reverse().ToArray()));
SLabel lbl = new SLabel(reversed)
{
Width = 150, Margin = new Thickness(5, 0, 0, 0)
};
this.Container.Children.Add(msg);
this.Container.Children.Add(lbl);
}
public void TestDiscreteCellValuesThenMerge()
{
DiscreteCellSink <int> c1 = DiscreteCell.CreateSink(9);
DiscreteCellSink <int> c2 = DiscreteCell.CreateSink(2);
List <int> @out = new List <int>();
IListener l = Transaction.Run(() => c1.Values.Merge(c2.Values, (x, y) => x + y).Listen(@out.Add));
c1.Send(1);
c2.Send(4);
Transaction.RunVoid(() =>
{
c1.Send(7);
c2.Send(5);
});
l.Unlisten();
CollectionAssert.AreEqual(new[] { 11, 1, 4, 12 }, @out);
}
public void Test_Apply_TestCase()
{
Tuple <Stream <int>, Dictionary <int, Action> > s1T = MkStream(new Dictionary <int, int> {
{ 1, 200 }, { 2, 300 }, { 4, 400 }
});
Stream <int> s1 = s1T.Item1;
Dictionary <int, Action> s1F = s1T.Item2;
DiscreteCell <int> ca = s1.Hold(100);
Tuple <Stream <Func <int, int> >, Dictionary <int, Action> > s2T = MkStream(new Dictionary <int, Func <int, int> > {
{ 1, x => x + 5 }, { 3, x => x + 6 }
});
Stream <Func <int, int> > s2 = s2T.Item1;
Dictionary <int, Action> s2F = s2T.Item2;
DiscreteCell <Func <int, int> > cf = s2.Hold(x => x + 0);
List <int> @out = RunSimulation <int>(ca.Apply(cf).Listen, new[] { s1F, s2F });
CollectionAssert.AreEqual(new[] { 100, 205, 305, 306, 406 }, @out);
}
public MainWindow()
{
this.InitializeComponent();
this.Container.Children.Add(Transaction.Run(() =>
{
FrTextField firstName = new FrTextField("Joe");
FrTextField lastName = new FrTextField("Bloggs");
FrButton ok = new FrButton(DiscreteCell.Constant("OK"));
FrButton cancel = new FrButton(DiscreteCell.Constant("Cancel"));
IReadOnlyList <Fridget> buttons = new[] { ok, cancel };
Fridget buttonPanel = new FrFlow(Orientation.Horizontal, buttons);
IReadOnlyList <Fridget> fridgets = new[] { buttonPanel, firstName, lastName };
Fridget dialog = new FrFlow(Orientation.Vertical, fridgets);
IListener lOk = ok.SClicked.Snapshot(firstName.Text, lastName.Text, (_, f, l) => f + " " + l).Listen(n => this.AddMessage("OK: " + n));
IListener lCancel = cancel.SClicked.Listen(_ => this.AddMessage("Cancel"));
return(new FrView(this, dialog, new CompositeListener(new[] { lOk, lCancel })));
}));
}
public void TestLiftListLarge()
{
IReadOnlyList <DiscreteCellSink <int> > cellSinks = Enumerable.Range(0, 500).Select(_ => DiscreteCell.CreateSink(1)).ToArray();
DiscreteCell <int> sum = cellSinks.Lift().Map(v => v.Sum());
List <int> @out = new List <int>();
IListener l = sum.Listen(@out.Add);
cellSinks[4].Send(5);
cellSinks[5].Send(5);
Transaction.RunVoid(() =>
{
cellSinks[9].Send(5);
cellSinks[17].Send(5);
cellSinks[41].Send(5);
cellSinks[48].Send(5);
});
l.Unlisten();
CollectionAssert.AreEqual(new[] { 500, 504, 508, 524 }, @out);
}
public void TestLiftInSwitchC()
{
IReadOnlyList <Test> list1 = new[] { new Test(0), new Test(1), new Test(2), new Test(3), new Test(4) };
IReadOnlyList <Test> list2 = new[] { new Test(5), new Test(6), new Test(7), new Test(8), new Test(9) };
DiscreteCellSink <IReadOnlyList <Test> > v = DiscreteCell.CreateSink(list1);
DiscreteCell <IReadOnlyList <int> > c = v.Map(oo => oo.Select(o => o.Value).Lift()).SwitchC();
List <IReadOnlyList <int> > streamOutput = new List <IReadOnlyList <int> >();
IListener l = c.Updates.Listen(streamOutput.Add);
List <IReadOnlyList <int> > cellOutput = new List <IReadOnlyList <int> >();
IListener l2 = c.Listen(cellOutput.Add);
list1[2].Value.Send(12);
list2[1].Value.Send(16);
list1[4].Value.Send(14);
Transaction.RunVoid(() =>
{
list2[2].Value.Send(17);
list1[0].Value.Send(10);
v.Send(list2);
});
list1[3].Value.Send(13);
list2[3].Value.Send(18);
l2.Unlisten();
l.Unlisten();
Assert.AreEqual(4, streamOutput.Count);
Assert.AreEqual(5, cellOutput.Count);
CollectionAssert.AreEqual(new[] { 0, 1, 2, 3, 4 }, cellOutput[0]);
CollectionAssert.AreEqual(new[] { 0, 1, 12, 3, 4 }, streamOutput[0]);
CollectionAssert.AreEqual(new[] { 0, 1, 12, 3, 4 }, cellOutput[1]);
CollectionAssert.AreEqual(new[] { 0, 1, 12, 3, 14 }, streamOutput[1]);
CollectionAssert.AreEqual(new[] { 0, 1, 12, 3, 14 }, cellOutput[2]);
CollectionAssert.AreEqual(new[] { 5, 16, 17, 8, 9 }, streamOutput[2]);
CollectionAssert.AreEqual(new[] { 5, 16, 17, 8, 9 }, cellOutput[3]);
CollectionAssert.AreEqual(new[] { 5, 16, 17, 18, 9 }, streamOutput[3]);
CollectionAssert.AreEqual(new[] { 5, 16, 17, 18, 9 }, cellOutput[4]);
}
private FrButton(DiscreteCell <string> label, StreamLoop <Unit> sClicked)
: base((size, sMouse, sKey, focus, idSupply) =>
{
Stream <Unit> sPressed = sMouse.Snapshot(size,
(e, mSize) => mSize.Bind(
s =>
{
MouseButtonEventArgs b = e.Args as MouseButtonEventArgs;
Point p = e.GetPosition();
return(b != null && b.ChangedButton == MouseButton.Left && b.ButtonState == MouseButtonState.Pressed &&
p.X >= 2 && p.X < s.Width - 2 && p.Y >= 2 && p.Y < s.Height - 2
? Maybe.Some(Unit.Value)
: Maybe.None);
})).FilterMaybe();
Stream <Unit> sReleased = sMouse.Snapshot(size,
(e, mSize) => mSize.Bind(
s => e.Args is MouseButtonEventArgs b && b.ChangedButton == MouseButton.Left && b.ButtonState == MouseButtonState.Released
? Maybe.Some(Unit.Value)
: Maybe.None)).FilterMaybe();
public void Run()
{
DiscreteCellSink <double> mainClock = new DiscreteCellSink <double>(0.0);
StreamSink <Unit> sPause = new StreamSink <Unit>();
StreamSink <Unit> sResume = new StreamSink <Unit>();
DiscreteCell <double> gameClock = PausableClock(sPause, sResume, mainClock);
IListener l = mainClock.Lift(gameClock, (m, g) => "main=" + m + " game=" + g).Listen(Console.WriteLine);
mainClock.Send(1.0);
mainClock.Send(2.0);
mainClock.Send(3.0);
sPause.Send(Unit.Value);
mainClock.Send(4.0);
mainClock.Send(5.0);
mainClock.Send(6.0);
sResume.Send(Unit.Value);
mainClock.Send(7.0);
l.Unlisten();
}
public Outputs Create(Inputs inputs)
{
LifeCycle lc = new LifeCycle(inputs.SNozzle1,
inputs.SNozzle2,
inputs.SNozzle3);
DiscreteCell <double> litersDelivered =
Accumulate(lc.SStart.Map(_ => Unit.Value),
inputs.SFuelPulses,
inputs.Calibration);
return(new Outputs()
.SetDelivery(lc.FillActive.Map(
m =>
m.Equals(Maybe.Just(Fuel.One)) ? Delivery.Fast1 :
m.Equals(Maybe.Just(Fuel.Two)) ? Delivery.Fast2 :
m.Equals(Maybe.Just(Fuel.Three)) ? Delivery.Fast3 :
Delivery.Off))
.SetSaleQuantityLcd(litersDelivered.Map(Formatters.FormatSaleQuantity)));
}
public MainWindow()
{
this.InitializeComponent();
SDateField dep = new SDateField();
SDateField ret = new SDateField();
Rule r1 = new Rule((d, r) => d <= r);
Rule r2 = new Rule((d, r) => !Unlucky(d) && !Unlucky(r));
Rule rule = r1.And(r2);
DiscreteCell <bool> valid = rule.Reify(dep.SelectedDate, ret.SelectedDate);
SButton ok = new SButton(valid)
{
Content = "OK", Width = 75
};
this.DeparturePlaceholder.Children.Add(dep);
this.ReturnPlaceholder.Children.Add(ret);
this.ButtonPlaceholder.Children.Add(ok);
}
public void PostInNestedConstructTransaction()
{
int value = 0;
Transaction.RunConstruct(() =>
{
StreamSink <int> s = Stream.CreateSink <int>();
s.Send(2);
Transaction.RunVoid(() =>
{
DiscreteCell <int> c = s.Hold(1);
Transaction.Post(() => value = c.Cell.Sample());
});
Assert.AreEqual(value, 0);
return(Unit.Value);
});
Assert.AreEqual(value, 2);
}