map_filder_reduce.cs

class Program
    {
        static void ExecuteAcionNTimes(int n, Action<int> cosDoZrobienia)
        {
            for (int i = 0; i < n; i++)
            {
                cosDoZrobienia.Invoke(i);
            }
        }

        static bool Exists<T>(List<T> elementy, Func<T, bool> warunek)
        {
            foreach (var element in elementy)
            {
                if (warunek(element) == true)
                {
                    return true;
                }
            }
            return false;
        }


        static T Find<T>(List<T> elementy, Func<T, bool> warunek)
        {
            foreach (var element in elementy)
            {
                if (warunek(element))
                {
                    return element;
                }
            }

            return default(T);
        }

        static List<R> Zip<T1, T2, R>(List<T1> list1, List<T2> list2, Func<T1, T2, R> konwerter)
        {
            List<R> wynik = new List<R>();

            var min = Math.Min(list1.Count, list2.Count);

            for (int i = 0; i < min; i++)
            {
                wynik.Add(konwerter(list1[i], list2[i]));
            }

            return wynik;
        }


        static List<T> FindAll<T>(List<T> items, Func<T, bool> predicate)
        {
            var result = new List<T>();
            foreach (var item in items)
            {
                if (predicate(item))
                {
                    result.Add(item);
                }
            }
            return result;
        }

        static List<T> FindAll<T>(List<T> items, Func<T, int, bool> predicate)
        {
            var result = new List<T>();
            int i = 0;
            foreach (var item in items)
            {
                if (predicate(item, i++))
                {
                    result.Add(item);
                }
            }
            return result;
        }

        static List<R> ConvertAll<T, R>(List<T> items, Func<T, R> converter)
        {
            var result = new List<R>();
            foreach (var item in items)
            {
                result.Add(converter(item));
            }
            return result;
        }

        static List<R> ConvertAll<T, R>(List<T> items, Func<T, int, R> converter)
        {
            var result = new List<R>();
            int i = 0;
            foreach (var item in items)
            {
                result.Add(converter(item, i++));
            }
            return result;
        }


        static void ForEach<T>(List<T> items, Action<T> action)
        {
            foreach (var item in items)
            {
                action(item);
            }
        }


        static A Fold<T, A>(List<T> items, A seed, Func<A, T, A> aggregator)
        {
            A total = seed;
            foreach (var item in items)
            {
                total = aggregator(total, item);
            }
            return total;
        }


        static List<R> Collect<T, R>(List<T> osoby, Func<T, List<R>> f)
        {
            var result = new List<R>();
            foreach (var osoba in osoby)
            {
                result.AddRange(f(osoba));
            }
            return result;
        }

        class Osoba
        {
            public int Id { get; set; }
            public string Name { get; set; }

            public List<Adres> Adresy { get; set; }
        }

        class Adres
        {
            public string City { get; set; }
        }

        static void Main(String[] args)
        {
            var osoby = new List<Osoba>
            {
                new Osoba()
                {
                    Id = 1,
                    Name = "Marcin",
                    Adresy = new List<Adres>
                    {
                        new Adres { City = "Wroclaw"} ,
                        new Adres { City = "Krakow"}
                    }
                },
                new Osoba() {
                    Id = 2,
                    Name = "Gosia",
                    Adresy = new List<Adres>
                    {
                        new Adres { City = "Warszawa"} ,

                    }}
            };

            var aa = Collect(osoby, o => o.Adresy); // Map, Select, ConvertAll

            var dic = Fold(osoby, new Dictionary<int, Osoba>(), (dic, o) =>
            {
                dic.Add(o.Id, o);
                return dic;
            });


            var a3 = Fold(
                  new List<int> { 1, 2, 3, 4, 66, 7, 8 },
                  0,
                  (prev, current) => prev + current);

            // int a = new int[] { 1, 2, 3, 4, 66, 7, 8 }.Aggregate(
            //     0, (prev, current) => prev + current);

            // int a2 = new int[] { 1, 2, 3, 4, 66, 7, 8 }.Aggregate(
            //     int.MinValue,
            //     (prev, current) => Math.Max(prev, current));

            var names = new List<string>()
            {
                "marcin", "gosia", "janusz", null
            };

            var temp1 = FindAll(names, n => n != null);
            var temp2 = ConvertAll(temp1, (n, index) => index + ". " + n.Length);




            ForEach(temp2, Console.WriteLine);

            // names
            //     .FindAll(n => n != null) // WHERE
            //     .ConvertAll(n => n.Length) // SELECT
            //     .ForEach(x =>
            //     {
            //         //todo: ... 
            //     });



            var datyUrodzenia = new List<DateTime>()
            {
                new DateTime(2000,1,1),
                new DateTime(2004,1,1),
                new DateTime(203,1,1)
            };
        }

        private static void WypiszZeCSharpJestOk(int x)
        {
            Console.WriteLine(" C# jest ok " + x);
        }

    }