If you don't understand the difference between "a function that sums a list of integers" and "a function that accepts a function", then Joel has a pretty decent

If you don't understand the difference between "a function that sums a list of integers" and "a function that accepts a function", then Joel has a pretty decent introduction you should read: http://www.joelonsoftware.com/items/2006/08/01.html http://www.joelonsoftware.com/items/2006/08/01.html