extension method on Func

FuncExt.cs

public static class FuncTest
{
    public static int TestMe()
    {
        Func<int, int> f = x => x + 5;
        var val = f.Fmap(x => x*2)(3);
        Console.WriteLine(val);
        return val;
    }

    public static Func<A, C> Fmap<A, B, C>(this Func<A, B> f, Func<B, C> g)
    {
        return x => g(f(x));
    }
}