// Advanced functional operations on arrays
var data: array of Integer = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

// Filter: keep only even numbers using lambda syntax
var evens := data.Filter(lambda (n) => n mod 2 = 0);
PrintLn('Evens: ' + evens.Map(IntToStr).Join(', '));

// Map: square the numbers
var squares := evens.Map(function (n: Integer): Integer 
  begin 
    Result := n * n; 
  end);
PrintLn('Squares of evens: ' + squares.Map(IntToStr).Join(', '));

// Foreach: iterate with a procedure
Print('Iterating squares: ');
squares.Foreach(procedure (n: Integer) 
  begin 
    Print(IntToStr(n) + ' '); 
  end);
PrintLn('');

// Contains and IndexOf
if data.Contains(7) then
  PrintLn('Data contains 7 at index ' + IntToStr(data.IndexOf(7)));