That's an outdated version of a bad book. That statement is completely false. Notice how as racket's type system improved, he continued to update the book to be more and more pro-types and removed more and more the deliberate FUD like that?
>There is one type system (with types such as int, double and even function types) at the level of the program
Yes, that is the only type system.
>and a different type system, defined solely by lengths of bitstrings, at the level of execution
That is not a type system. By definition type systems are at the program level. Data classification occurs at the level of execution, and such a system exists in virtually every language whether it has a type system or not.
If you have ever used the phrases “strong typing” or “weak typing”, define them.
That’s what I thought. But thank you for playing.
Indeed, the phrases are not only poorly defined, they are also wrong, because the problem is not with the “strength” of the type checker but rather with the nature of the run-time system that backs them.
>There is one type system (with types such as int, double and even function types) at the level of the program
Yes, that is the only type system.
>and a different type system, defined solely by lengths of bitstrings, at the level of execution
That is not a type system. By definition type systems are at the program level. Data classification occurs at the level of execution, and such a system exists in virtually every language whether it has a type system or not.