Re: [RFC] Four Pragmatic Directions for PHP: Simplicity, Arrays, Performance, Concurrency

I used to have a really long and interesting blog post on PHP arrays about this: On Tue, Mar 24, 2026, at 12:04, Dan Liebner wrote: > I agree with this sentiment. > > My main gripe with PHP 8 is that undefined array key accesses trigger a warning. There is no > solution to this that doesn't require destroying the readability of a legacy codebase or using > some hacky global error handler. > > I think the direction should always have been this: undefined array key accesses should simply > return null by default. And then my disk caught on fire and it was never archived. TL;DR: treating PHP arrays as an infinite field of nulls has some very interesting mathematical properties. No other language on earth gave you this. Practical usecases were ways to effectively "cheat" on some np-hard and np-complete problems, like subset-sum, knapsack, Hamiltonian Path, etc. This warning (and eventual removal of this property) makes these "cheats" no longer possible in PHP and constrained just like every other language on the planet. — Rob