How to make an Expression Tree.

I want to make this lambda expression.

Func mean = (x, y) => ((x + y) / 2);

Console.WriteLine(mean(10, 20));

Use Expression class.

ParameterExpression x = Expression.Parameter(typeof(int), "x");
ParameterExpression y = Expression.Parameter(typeof(int), "y");

ConstantExpression two = Expression.Constant(2, typeof(int));

BinaryExpression add = Expression.Add(x, y);
BinaryExpression body = Expression.Divide(add, two);

Expression<Func<int, int, int>> meanExp =
    Expression.Lambda<Func<int, int, int>>(
        body,
        new ParameterExpression[] { x, y });
Func<int, int, int> mean = meanExp.Compile();

Console.WriteLine(meanExp);
Console.WriteLine(mean(10, 20));