dimitris-papadimitriou-chr

       abstract class Shape
        {
            public abstract string GetShapeDescription();
        }
        class Rectangle : Shape
        {
            public int Width { get; set; }
            public int Height { get; set; }

            public override string GetShapeDescription()

dimitris-papadimitriou-chr

  string GetShapeDescription(Shape shape)
            {
                switch (shape)
                {
                    case Circle c:
                        return $"found a circle with radius {c.Radius}";
                    case Rectangle s:
                        return $"Found {s.Height }x {s.Width} rectangle";
                    default:
                        throw new System.Exception(nameof(shape));

dimitris-papadimitriou-chr

                string GetShapeDescription1(Shape shape)
                {
                    if (shape is Circle)
                        return $"found a circle with radius {(shape as Circle).Radius}";
                    if (shape is Rectangle)
                        return $"Found {(shape as Rectangle).Height }x {(shape as Rectangle).Width} rectangle";

                    throw new System.Exception(nameof(shape));
                }

dimitris-papadimitriou-chr

        abstract class Shape { }

        class Rectangle : Shape
        {
            public int Width { get; set; }
            public int Height { get; set; }
        }

        class Circle : Shape
        {

dimitris-papadimitriou-chr

    class Balance {
        
        static Left = new Balance(0, 1)
        static Right = new Balance(1, 0)
        static Empty = new Balance(0, 0)

        L: number
        R: number
        constructor(l: number, r: number) {

dimitris-papadimitriou-chr

    var weight = new MonoidWeight();
    var parsed = Array.from("(()))").map(parse).reduce(weight.concat,weight.empty);

dimitris-papadimitriou-chr

    var parse: (c: string) => Balance = (c: string) => {
          switch (c) {
            case "(": return Balance.Left
            case ")": return Balance.Right
            default:  return Balance.Empty
        }
    }

dimitris-papadimitriou-chr

    class MonoidWeight implements monoid<Balance> {
        empty: Balance = Balance.Empty;
        concat(x: Balance, y: Balance): Balance {
            if (x.R < y.L)
                return new Balance(x.L + y.L - x.R, y.R);
            else
                return new Balance(x.L, y.R + x.R - y.L);
        }
    }

dimitris-papadimitriou-chr

    class Balance {
        
        static Left = new Balance(0, 1)
        static Right = new Balance(1, 0)
        static Empty = new Balance(0, 0)

        L: number
        R: number
        constructor(l: number, r: number) {
            this.L = l;

dimitris-papadimitriou-chr

 var sum = fold([2, 3, 4], Sum.empty, Sum.concat);
var product = fold([2, 3, 4], 1, (x, y) => x * y);
var max = fold([2, 3, 4], Number.MIN_SAFE_INTEGER, (x, y) => x > y ? x : y);