Enumeration.as

/**
 * AS3 implementation of Ruby Enumeration class
 */
public dynamic class Enumerable
{
	private var _array:Array;
	
	public function Enumerable(... parameters) {
		if(parameters != null)
			_array = parameters;
		else
			_array = new Array();
	}

	/**
	 * f(item:*):Boolean;
	 */
	public function detect(f:Function):Object {
		var first:Object;
		var detected:Boolean;

		detected = _array.some(function(item:Object, i:int, a:Array):Boolean {
			first = item;
			return f(item);
		});

		return (detected ? first : null);
	}
	
	/**
	 * f(item:*):Boolean;
	 */
	public function select(f:Function):Object {
		return _array.filter(function(item:Object, index:int, array:Array):Boolean {
			return f(item);
		});
	}
	
	/**
	 * f(item:*):Object;
	 */
	public function map(f:Function):Array {
		var array:Array =  new Array();

		_array.forEach(function(item:Object, i:int, a:Array):void {
			array.push(f(item));
		});
		
		return array;
	}
	
	/**
	 * f(memo:Object, item:*):Object;
	 */
	public function reduce(initial:Object ,f:Function):Object {
		var memo:Object = initial;

		_array.forEach(function(item:Object, i:int, a:Array):void {
			memo = f.call(null, memo, item);
		});

		return memo;
	}

}

Some examples:

var array:Enumerable = new Enumerable(1, 2, 3);

array.detect(function(n:Number):Boolean { return n == 2; }); // 2
array.select(function(n:Number):Boolean { return n > 1; }); // 2,3
array.map(function(n:Number):Number { return n % 2; }); // 1,0,1
array.reduce(0, function(a:Number, n:Number):Number { return a + n; }); // 6

Taste it at http://eval.hurlant.com/demo