Probable C# 6.0 features

[Robert Clipsham]

On Tuesday, 10 December 2013 at 20:35:08 UTC, Namespace wrote:
> I love Monadic null checking. Would be great if D would have it.

Doesn't need to be a language feature - you can implement it as a 
library type. Here's a quick hacked together maybe monad:

----
import std.stdio;

struct Maybe(T)
{
     private T val = null;

     this(T t)
     {
         val = t;
     }

     auto opDispatch(string method, U...)(U params)
     {
         alias typeof(mixin("val." ~ method ~ "(params)")) retType;
         if (val) {
             mixin("return Maybe!(" ~ retType.stringof ~ ")(val." 
~ method ~ "(params));");
         }
         return nothing!retType();
     }
}

Maybe!T just(T)(T t)
{
     return Maybe!T(t);
}

Maybe!T nothing(T)()
{
     return Maybe!T();
}

class Foo
{
     Bar retNull()
     {
         writeln("foo null");
         return null;
     }

     Bar notNull()
     {
         writeln("foo not null");
         return new Bar();
     }
}

class Bar
{
     Foo retNull()
     {
         writeln("bar null");
         return null;
     }

     Foo notNull()
     {
         writeln("bar not null");
         return new Foo();
     }
}

void main()
{
     auto maybe = just(new Foo);
     maybe.notNull().notNull().notNull().retNull().notNull();
}

----