The problem with built-in generics is that they are quite ad-hoc and hard to reason about. Each generic built-in function is re-implemented by hand in the compi

The problem with built-in generics is that they are quite ad-hoc and hard to reason about. Each generic built-in function is re-implemented by hand in the compiler. If we call this type of ad-hoc implementation "generics", we're going down a very deep rabbit hole, since then almost any programming language can be said to have generics. For instance, Write[Ln] in Pascal, sizeof() in C, all array functions in Java pre-1.5. In other words, technically when people say "Language X lacks generics" they always mean "Language X lacks orthogonal, predictable, non ad-hoc, user defined generics".