5 ms·
In PHP array_sum([1, 2, 3, 4, 5]);
by sevenproxies 13y ago
In PHP
array_sum([1, 2, 3, 4, 5]);
- DorianMarie 13y agoarray_sum_of_1_2_3_4_5(); (Added in PHP 6)
- x3ro 13y agoMade me laugh :)
- krapp 13y agothe funny thing is, with proper abuse of __call you can almost get that to work: https://gist.github.com/kennethrapp/328b6bd1bda8a8f94092 https://gist.github.com/kennethrapp/328b6bd1bda8a8f94092
- aaronem 13y agoThat's not funny. Horrifying, maybe, but not funny. Edit: Strike 'maybe'. I looked at it again and it's definitely horrifying. I saved it anyway, though; Halloween's only a few weeks off, and I think I shall print it out and stick it on the wall of my cube next to the PHP hammer and the "periodic" table of Perl 6 operators.
- agumonkey 13y agokudos. almost as cool as the cpp template hack to compute area based on part of the source code 'ascii art' size. (which I can't find anymore. googlefu--)
- tel 13y agoIn 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 foldable thing—anything which has elements which can be combined together one-by-one. So it'll apply to Trees or Sets or Dictionaries (well, Maps) just as easily while also allowing things like (+) to be replaced by other binary operators.
- Scriptor 13y agoPHP does have array_reduce, however operators like '+' can't be used as callables so you'd have to make your own wrapper functions. Edit: Screw it, haven't self promoted on a while. In Pharen (https://github.com/scriptor/pharen https://github.com/scriptor/pharen), which compiles to PHP, you could do: (reduce (+) 0 [1 2 3 4 5])
- tel 13y agoThat's really cool, but the syntax is strange to me. How do you distinguish between operator sectioning (+) and a side-effecting function call (f)?
- Scriptor 13y agoIt works (superficially) similarly to how Haskell does things and treats (+) as a partial function call by recognizing that + isn't getting at least 2 arguments. You could also do stuff like: ((+ 1) 2) ; => 3 (map (* 2) [1 2 3]) ; => [2 4 6] If a function f takes any arguments and Pharen knows this, it'll convert (f) into a partial function call as well. Unfortunately I haven't figured out a way to check if a function has any side effects. Otherwise in this case at least operators are treated like functions.
- tel 13y agoSo it's tracking the arity of functions and turning anything which has been applied to fewer than ARITY arguments to a partial application? I suppose that comes at the cost of (+ 1 2 3 4)?
- aaronem 13y agoWhy would it?
- tel 13y agoMy hypothesis was that the compiler was tracking the arities of each function in order to open up opportunities for partial application. That means there's some ambiguity when you write something like (+ 1) which, in Scheme is a complete application equal to 1 but may also be interpreted as a partial application equal to (lambda (x) (+ 1 x)). There are many ways to mitigate that ambiguity statically and dynamically, but I feel there's always going to be a tradeoff between favoring partial application, favoring variadic functions, and the complexity/sophistication of your static checking or runtime environment. I just made a stab at where the solution might lie in that design space. Turns out I was wrong.
- TylerE 13y agoirb(main):001:0> x = [1,2,3,4,5] => [1, 2, 3, 4, 5] irb(main):002:0> x.inject &:* => 120
- cheald 13y agoThe GP's point is that Ruby doesn't require a built-in method that specifically sums an array to still get a clean, terse operation. You can use #inject to apply an arbitrary operation to (operator, last result, current element) and arrive at a result. For example, given a list of numbers, you can generate a bitwise OR mask easily: [1,2,3,4,5].inject(:|) What this does is iterate over the list and apply ($last_result | $current_element) and return the result, which is passed on as $last_result to the next iteration. $last_result is 0 by default. This is equivalent to (as of PHP 5.4): array_reduce([1,2,3,4,5], function($v, $e) { return $v | $e; }, 0); Or prior to PHP 5.3: function or_mask($v, $e) { return $v | $e; } array_reduce(array(1,2,3,4,5), "or_mask", 0); It's doable in both languages, but Ruby's functional language lineage and its object-oriented nature results in an exceptionally clean approach.