Coolest C# LINQ/Lambdas trick you've ever pulled?

Question

Saw a post about hidden features in C# but not a lot of people have written linq/lambdas example so... I wonder...

What\'s the coolest (as in the most

Answer 1

Some basic functionals:

public static class Functionals
{
    // One-argument Y-Combinator.
    public static Func Y(Func, Func> F)
    {
        return t => F(Y(F))(t);
    }

    // Two-argument Y-Combinator.
    public static Func Y(Func, Func> F)
    {
        return (t1, t2) => F(Y(F))(t1, t2);
    }

    // Three-arugument Y-Combinator.
    public static Func Y(Func, Func> F)
    {
        return (t1, t2, t3) => F(Y(F))(t1, t2, t3);
    }

    // Four-arugument Y-Combinator.
    public static Func Y(Func, Func> F)
    {
        return (t1, t2, t3, t4) => F(Y(F))(t1, t2, t3, t4);
    }

    // Curry first argument
    public static Func> Curry(Func F)
    {
        return t1 => t2 => F(t1, t2);
    }

    // Curry second argument.
    public static Func> Curry2nd(Func F)
    {
        return t2 => t1 => F(t1, t2);
    }

    // Uncurry first argument.
    public static Func Uncurry(Func> F)
    {
        return (t1, t2) => F(t1)(t2);
    }

    // Uncurry second argument.
    public static Func Uncurry2nd(Func> F)
    {
        return (t1, t2) => F(t2)(t1);
    }
}

Don't do much good if you don't know how to use them. In order to know that, you need to know what they're for:

• What is currying?
• What is a y-combinator?