It has nothing to do with being “too hard”, and everything to do with not making sense to the type system. PHP is weakly-typed and heavily reflection-based (so everything is aware of it’s and each other’s type at all times).
Adding generics to PHP would make CS fundamentalists somewhat happy, but do nothing to change the fundamental design of PHP nor offer any of the traditional benefits that generics offer to strongly-typed and compiled languages. And would be a massive headache to implement, while bulking an already heavy VM implementation.
Adding generics to PHP would make CS fundamentalists somewhat happy, but do nothing to change the fundamental design of PHP nor offer any of the traditional benefits that generics offer to strongly-typed and compiled languages. And would be a massive headache to implement, while bulking an already heavy VM implementation.