387: Mainline

Yet another, much more elegant way to add up the numbers in an array is to use the powerful inject:into: method, inherited from the Collection class, with a two-argument block:

an Array instance  
  inject: initial value  
  into: [:previousResult :nextElement | statements]   

Here is what happens when you send a inject:into: method:

• The initial value is assigned to previousResult, and the first element in the array is assigned to nextElement.
• The statements are evaluated to produce a value for the block.
• The value of the block is assigned to previousResult, and the second element in the array is assigned to nextElement.
• The statements are evaluated again.
• The previous steps are repeated for all the elements in the array. The answer of the overall inject:into: is the value produced by the final evaluation of the block.