Ruby

Kernel#loop wraps use of Enumerator rescuing StopIteration raised by Enumerator#next, but it does not provide access to the "result" value of a finished enumerator.
If you wanted to get it, you'd have to rescue StopIteration by yourself.

result = loop { begin puts enum.next rescue StopIteration => exc break exc.result end } 

This feels awkward when loop is capable of rescuing the exception.

So, my proposal here is to make Kernel#loop return the "result" value, which currently returns nothing (nil).
Kernel#loop takes a "return" of an enumerator (StopIteration) as "break" of a loop, so it should be natural to be able to carry a returned value through to the caller like it was given with "break".

With this enhancement, you could write something like this:

enum = Enumerator.new { |y| y << 1 y << 2 :ok } result = loop { puts enum.next } #=> :ok 

Attached is my implementation.