Monad like programming with C#.
An abstract base class Monad that extends IEnumerable, IObservable and IObserver.
Some implementations of the Monad:
- Maybe
- Identity
- List monad
- CacheMonad
- (Either is mostly untested, it is some kind of decorator) (Update: currently not working!)
Lots of extension methods (LiftMonad, Comparator functions, easy thread safe function application).
See Doc folder for detailed description an introduction.
Have a look at the Playground.cs for more examples.
A little intro how to use it:
// Creating new maybes using implicit operator overloadings
Maybe<int> justInt = 5;
// Implicit operator checks value for default(T).
// So this becomes a Nothing<int>
Maybe<int> nothingInt = 0;
var intToDoubleFunction = new Func<int, double>(x => { return x * 0.5; });
Just<double> justDouble = justInt.Fmap(intToDoubleFunction);
// Identity atomic extensions
Identity<int> intId = 5;
if(intId.CompareExchange(42, (i) => i % 2 == 1))
{
// ....
} ListMonad<int> listMonadInt = new ListMonad<int>() { 1, 2, 3, 4, 5 };
ListMonad<double> listMonadDouble = new ListMonad<double>() {1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0};
listMonadInt.Fmap((x) => { return 0.5 * x;});
Func<int, double> intDoubleFunc1 = (x) => { return 0.5 * x; };
Func<int, double> intDoubleFunc2 = (x) => { return 0.7 * x; };
var lmIntDblFunc = new ListMonad<Func<int, double>>() { intDoubleFunc1, intDoubleFunc2 };
ListMonad<Double> result = listMonadInt.App(lmIntDblFunc);Using IObserver/IObservable extensions, and ActionW/MethodW thread safe function application.
Identity<string> id = "string";
Identity<string> observer = "";
observer.Disposable = id.Subscribe(observer);
// or observer.SubscribeAt(id);
observer.NextAction = (m, x) => Console.WriteLine("Received next: " + x);
observer.CompleteAction = (m) => Console.WriteLine("Completed, last value: " + m.Return();
observer.ErrorAction = (e) => Console.WriteLine(e.Message);
// Using Subscribe from reactive extensions
id.Subscribe((s) => Console.WriteLine("Anonymour Observer Received next: " + s),
(e) => Console.WriteLine(e.Message),
() => Console.WriteLine("Completed"));
// Both lines will change the value inside the id monad.
// The observer monads OnNext will be called.
id.ActionW((i) => i.Pure("1"));
id.ActionW(() => id.Pure("2"));
public static Func<string, string> setString = (s) => s += "foobar ";
// Adding the string foobar to the current string inside the identity two times,
// in different ways.
id.MethodW(() => { return id.Pure(id.Fmap(setString).Return()); });
id.ActionW(() => id.Pure(id.Fmap(setString).Return()));
id.EndTransmission();
// Functions for combination with IMonad as result.
Func<int, double, IMonad<double>> intDblIMonadDblF1 =
(x, y) => { return new Just<double>((double)x + y); };
Func<int, double, IMonad<double>> intDblIMonadDblF2 =
(x, y) => { return new Just<double>((double)x - y); };
Func<int, double, IMonad<double>> intDblIMonadDblF3 =
(x, y) => { return new Just<double>((double)x * y); };
Func<int, double, IMonad<double>> intDblIMonadDblF4 =
(x, y) => { return new Just<double>((double)x / y); };
Func<int, double, IMonad<double>> intDblIMonadDblF5 =
(x, y) => { return new ListMonad<double>(){(double)x % y}; };
Func<int, double, IMonad<double>> intDblIMonadDblF6 =
(x, y) => { return new ListMonad<double>() { (double)x * y * y, (double) x * y * y * y }; };
Func<int, double, IMonad<double>> intDblIMonadDblF7 =
(x, y) => { return new Nothing<double>(); };
var listMonadIntDblIMonadDblFunc = new ListMonad<Func<int, double, IMonad<double>>>()
{intDblIMonadDblF1,
intDblIMonadDblF2,
intDblIMonadDblF3,
intDblIMonadDblF4,
intDblIMonadDblF5,
intDblIMonadDblF6,
intDblIMonadDblF7};
ListMonad<int> listMonadInt = new ListMonad<int>() { 1, 2, 3, 4, 5 };
ListMonad<double> listMonadDouble = new ListMonad<double>() {1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0};
Console.WriteLine("Function applying with Linq: \n" +
" from f in [+, -, *, %]\n" +
" from x in [1,..,5]\n" +
" from y in [1.0,..,9.0] \n"+
" select f(x,y) \n");
var query = from f in listMonadIntDblIMonadDblFunc
from x in listMonadInt
from y in listMonadDouble
select f(x, y);
counter = 0;
// Query is a IMonad again
query.Visit((x) =>
{
Console.Out.Write(x + ", ");
counter++;
if (counter % 9 == 0)
Console.WriteLine("");
if (counter % (5 * 9) == 0)
Console.WriteLine("------------------------------------------------");
});