PHP Type Alias

In contrast to TypeScript or Flow, which can only check the program flow at compile time, PHP will crash and burn if you pass an int into a string function parameter at runtime.

Would you expect the presumed type aliases to be checked at runtime too?

There are already union types in PHP 8, but no aliases.

I think in PHP it is always the best approach to work with classes, whose type you can check at runtime (in contrast to duck-typed languages such as JS, where there is instanceof but that is generally a last resort).

Structural types checked at compile time are a different approach to the one PHP chose I think. Alhough the lines between compilation and execution are blurry in a JIT language of course.

I had in mind the modern C++ `using` mechanism for creating my own types, but didn't know how to write such logic.

I guess a union would be handy dealing with different alias types, depending on the use case, if you understand what I mean.

On the other hand, `match` is far better to be used if we really get type aliases as you suggest.

Something like `alias Numeric as int|float;`