Earlier quoted context omitted.
In PHP array_sum([1, 2, 3, 4, 5]);
In case this was a serious entry... which I honestly can't tell. The problem with array_sum is not that it's too long but instead that it's combined two rather specific bits of functionality into a fixed (if common) form, while the Ruby code separates the ideas of "folding" and "addition" allowing for many orthogonal creations. To pick another favorite, in Haskell you could write Foldable.foldl1 (+) which sums any fo…
Edit: Screw it, haven't self promoted on a while. In Pharen (https://github.com/scriptor/pharen), which compiles to PHP, you could do:
(reduce (+) 0 [1 2 3 4 5])