I assume that "local inference" means, in practice, "no let-polymorphism". That's what causes most of the headaches with extensions to Hindley-Milner (including the undecidability of subtyping).
PHP's syntax is not what's preventing you from writing large maintainable systems in it. Many of the more successful languages throughout history became successful BECAUSE they used a syntax that's superficially similar…
I assume that "local inference" means, in practice, "no let-polymorphism". That's what causes most of the headaches with extensions to Hindley-Milner (including the undecidability of subtyping).
PHP's syntax is not what's preventing you from writing large maintainable systems in it. Many of the more successful languages throughout history became successful BECAUSE they used a syntax that's superficially similar…