[dietrichepp]

You are choosing a definition of strong typing that supports your argument, but the argument is over the meaning of strong typing to begin with. It's not as if there's some universally accepted definition of strong typing. Like functional programming, functional purity, object oriented, etc.—none of these terms are universally defined.

[haberman]

The fact that "strong typing" has no universal definition is exactly why I think it's not useful.

[jcrites]

I hate feeling like I'm nitpicking, but I don't think that's true. I think they do have a well-accepted definition, which appears in Wikipedia, in assorted articles online, and in computer science publications. Here are some examples of CS publications that describe a research contribution in terms of strong typing:

> Strong typing of object-oriented languages revisited. This paper is concerned with the relation between subtyping and subclassing and their influence on programming language design. [...] The type system of a language can be characterized as strong or weak and the type checking mechanism as static or dynamic. http://dl.acm.org/citation.cfm?id=97964

> GALILEO: a strongly-typed, interactive conceptual language. Galileo, a programming language for database applications, is presented. Galileo is a strongly-typed, interactive programming language designed specifically to support semantic data model features (classification, aggregation, and specialization), as well as the abstraction mechanisms of modern programming languages (types, abstract types, and modularization). http://dl.acm.org/citation.cfm?id=3859

> Design and implementation of an object-oriented strongly typed language for distributed applications. http://dl.acm.org/citation.cfm?id=99813

> Strongly typed heterogeneous collections. (Oleg Kiselyov et al.) http://dl.acm.org/citation.cfm?id=1017488

> Strongly typed genetic programming. Genetic programming is a powerful method for automatically generating computer programs via the process of natural selection [but] there is no way to restrict the programs it generates to those where the functions operate on appropriate data types. [When] programs manipulate multiple data types and contain functions designed to operate on particular data types, this can lead to unnecessarily large search times and/or unnecessarily poor generalization performance. Strongly typed genetic programming (STGP) is an enhanced version of genetic programming that enforces data-type constraints and whose use of generic functions and generic data types makes it more powerful than other approaches to type-constraint enforcement http://dl.acm.org/citation.cfm?id=1326695

The argument that the terms have no universal definition cannot be sound in light of their widespread use in computer science publications, even in the title and abstract. Perhaps what you mean to say is that the terms don't have a completely unambiguous or formal definition. That's probably true, but not all CS terms do. The words are contextual and exist on a spectrum, in the sense that a strongly-typed thing is typically in comparison to a more-weakly-typed thing [1]. However, the fact that they're widely used by CS researchers is why I think we should reject the argument that they don't have a universal definition or are not useful. CS researchers like Oleg Kiselyov use the term when describing their papers and characterizing their contributions.

[1] This is true for static and dynamic typing as well: they exist in degrees. Rust can verify type proofs that other languages can't regarding memory safety. Some languages can verify that integer indexes into an array won't go out of bounds. Thus it's not the case that a given language is either statically typed or dynamically typed; rather, each aspect of how it works can be characterized on a spectrum from statically verified to dynamically verified.

[haberman]

> I think they do have a well-accepted definition [...] [You] shouldn't confuse your dislike for them for the absence of a well-accepted definition that's widely used in computer science literature.

Just upthread, you said:

> The notions of "strong" and "weak" typing have never been particularly well-defined

And the Wikipedia article you cited (https://en.wikipedia.org/wiki/Strong_and_weak_typing) says:

> These terms do not have a precise definition

The Wikipedia article also says:

> A number of different language design decisions have been referred to as evidence of "strong" or "weak" typing. In fact, many of these are more accurately understood as the presence or absence of type safety, memory safety, static type-checking, or dynamic type-checking.

Also on Wikipedia (https://en.wikipedia.org/wiki/Type_system):

> Languages are often colloquially referred to as "strongly typed" or "weakly typed". In fact, there is no universally accepted definition of what these terms mean. In general, there are more precise terms to represent the differences between type systems that lead people to call them "strong" or "weak".

...which is exactly what I'm saying in this entire thread.

It's very strange to me how you seem really seem to want other people to be on board with your particular interpretation of what everybody (even you, 13 hours ago) agrees is not a very well-defined concept.

[haberman]

> This is true for static and dynamic typing as well: they exist in degrees. Rust can verify type proofs that other languages can't regarding memory safety. Some languages can verify that integer indexes into an array won't go out of bounds. Thus it's not the case that a given language is either statically typed or dynamically typed

Memory safety and static/dynamic typing are orthogonal. C is statically typed but memory unsafe. Rust is statically typed but memory safe (except in unsafe blocks). Lua is dynamically-typed but memory safe.

I agree that it's possible to mix elements of static and dynamic typing in a single language. C++ is generally statically typed, but also supports dynamic_cast<>.

But generally speaking, static and dynamic typing have a very precise definition. Something that carries around type information at runtime is dynamically typed. Something that does type analysis at compile time so that the runtime doesn't need to carry type information is statically typed.