CS1Program.cs

using System;

namespace ConsoleApplication
{
    delegate int Op (int a);
    delegate int TwoOp (int a, int b);
    delegate Op CurriedOp (int a);
    
    class OpCurryer {
        private TwoOp f;
        private int a;

        public OpCurryer(TwoOp f) {
            this.f = f;
        }

        private int op2(int b) {
            return f(a, b);
        }

        private Op op1(int a) {
            this.a = a;
            return new Op(op2);
        }

        public CurriedOp GetCurriedOp() {
            return new CurriedOp(op1);
        }
    }

    class Composer {
        private Op op1;
        private Op op2;

        public Composer(Op op1, Op op2) {
            this.op1 = op1;
            this.op2 = op2; 
        }
        
        private int Composed(int a) {
            int x = op1(a);
            int y = op2(x);
            return y;
        }

        public Op GetComposedOp() {
            return new Op(Composed);
        }
    }

    public class Program
    {
        private static int DoubleUp(int a) { 
            Console.WriteLine("Doubling Up...");
            return a + a; 
        }

        private static int Square(int a) { 
            Console.WriteLine("Squaring ...");
            return a * a; 
        }

        private static int Addition(int a, int b) {
            Console.WriteLine("Adding ...");
            return a + b;
        }

        private static Op Compose(Op f1, Op f2) {
            Composer co = new Composer(f1, f2);
            return co.GetComposedOp();
        }

        private static int Compose(Op f1, Op f2, int input) {
            int x = f1(input);
            int y = f2(x);
            return y;
        }

        private static CurriedOp Curry(TwoOp f) {
            OpCurryer oc = new OpCurryer(f);
            return oc.GetCurriedOp();
        }

        public static void Main(string[] args)
        {
            Op op1 = new Op(DoubleUp);
            Op op2 = new Op(Square);
 
            Console.WriteLine("first class");
            Console.WriteLine(op1(45));

            Console.WriteLine("composition -- sort of");
            Op composed = new Op(DoubleUp);
            composed += new Op(Square);
            Console.WriteLine(composed(5));

            Console.WriteLine("composition -- No, not really");
            Console.WriteLine(Compose(op1, op2, 5));

            Console.WriteLine("Better composition");
            Console.WriteLine(Compose(op1, op2)(5));

            Console.WriteLine("Currying");
            TwoOp add = new TwoOp(Addition);
            Console.WriteLine(Curry(add)(5)(12));

            Console.WriteLine("Partial application");
            TwoOp addAgain = new TwoOp(Addition);
            Op addFive = Curry(add)(5);
            Console.WriteLine(addFive(12));
            Console.WriteLine(addFive(1084));
        }
    }
}

CS2Program.cs

using System;
using System.Collections.Generic;

namespace ConsoleApplication
{
    delegate int Op (int a);

    public class Program
    {
        private static int DoubleUp(int a) { return a + a; }

        private static IEnumerable<int> GetRange(int uBound) {
            for (int cur = 1; cur <= uBound; cur++) {
                yield return cur;
            }
        }

        private static IEnumerable<int> InfiniteList(int uBound) {
            int cur = 1;
            while (true) 
            {
                yield return cur;
                cur++;
            }
        }


        public static void Main(string[] args)
        {
            Console.WriteLine("Method group conversion");
            Op op1 = DoubleUp;
            Console.WriteLine(op1(45));

            Console.WriteLine("Anonymous methods");
            int b = 23;
            Op op2 = delegate(int a) { return a + b;};

            Console.WriteLine("Watch out for mutability in the closure");
            Console.WriteLine(op2(45));
            b = 5;
            Console.WriteLine(op2(45));

            Console.WriteLine("Iterators");
            foreach (int number in GetRange(12))
            {
                Console.WriteLine(number);
            }

            Console.WriteLine("Lazy Evaluation");
            
            
        }
    }
}

CS3Program.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication
{
    delegate int Op(int a);

    public class Program
    {
        public static void Main(string[] args)
        {
            Console.WriteLine("Lambdas");
            Op op1 = a => {return a + a;};
            Console.WriteLine(op1(7));

            Op op2 = a => a + a;
            Console.WriteLine(op2(12));

            Console.WriteLine("Query Expressions");
            var source = new List<int> {12, 13, 2, 15, 27, 20, 100, 34, 17, 18};
            var newList = from a in source 
                            where a%2 == 0
                            orderby a ascending
                            select a * -1;
            foreach (int x in newList) Console.WriteLine(x);

            Console.WriteLine("Method chaining syntax");
            var anotherList = source.Where(a => a%2==0)
                                .OrderBy(a => a)
                                .Select(a => a * -1);
            foreach (int x in anotherList) Console.WriteLine(x);

        }
    }
}