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> If you can cast in Python like you can cast in C, I don't know about it. Note that "cast" and "coerce" are different. Python supports coercion but not castin

> If you can cast in Python like you can cast in C, I don't know about it. Note that "cast" and "coerce" are different. Python supports coercion but not casting. Casting is an operation done in static type systems where you tell the compiler "I know this has type X, but pretend it has type Y". Coercion is a run-time operation which moves data from a box of one type into a box of a new type (i.e., a new object is allocated). > Part of the problem is that we've lost a whole quadrant of languages in the static-dynamic weak-strong graph: Weak dynamic typing is nonexistent these days. I'm not sure what you mean by "the problem" here. Weak dynamic type systems are, in my opinion, the worst of all worlds. They provide neither compile-time checks nor runtime checks that really amount to much. I don't know why you would ever prefer a weak dynamic type system in a language. JavaScript is essentially weak and dynamically typed. The weak part comes from all the implicit coercions the language inserts to ensure your code nearly always produces some result. This is terrible because it makes identifying errors exceptionally more difficult than in a strong or static type system.

msla 7y ago
> Note that "cast" and "coerce" are different. Python supports coercion but not casting. Casting is an operation done in static type systems where you tell the compiler "I know this has type X, but pretend it has type Y". Coercion is a run-time operation which moves data from a box of one type into a box of a new type (i.e., a new object is allocated). Right. I know this, I just call coercion "autoconversion" because the data is typically given a new form as well as a new box. Having autoconversion without casting is a sign of a strong type system, because you can't turn off the type system, you are only allowed to use it. If there's no way to autoconvert from type A to type B, that's it: You can't turn a value of type A into one of type B by hook or by crook. > I'm not sure what you mean by "the problem" here. "Problem" in the sense of our discussion being incomplete, nothing more. > Weak dynamic type systems are, in my opinion, the worst of all worlds. They provide neither compile-time checks nor runtime checks that really amount to much. I don't know why you would ever prefer a weak dynamic type system in a language. I agree with all of this. > JavaScript is essentially weak and dynamically typed. Wrong, for the reasons I went over in other posts.
- DonaldPShimoda 7y ago
  Ah I didn't realize I had replied to the same person in different places. Sorry about that haha. > I know this, I just call coercion "autoconversion" because the data is typically given a new form as well as a new box. Hmm interesting. I think I dislike this because coercion is not always automatic, so the "auto" part of "autoconversion" is a hang-up for me. For example, doing `int("3")` in Python is an explicit coercion, but I don't think it would qualify as an "autoconversion" (unless I'm not quite understanding your definition of that term). In the interests of clarity until I understand better, I'll continue using "coercion" and I'll specify implicit vs. explicit as needed. > Having autoconversion without casting is a sign of a strong type system, because you can't turn off the type system, you are only allowed to use it. I agree for explicit coercion, but not with implicit. If your coercion is implicit, then the user has no control over what's going on. The type system is essentially transforming values' types behind the curtain in an effort to prevent errors. This means that errors which the user might believe should be raised may not be. The type system is "weak" because it's not holding types rigidly with respect to the user's perspective. The user's perspective is key, because if we look at things from the language's perspective then almost any language could be viewed as strongly typed given the right theoretical framework. > "Problem" in the sense of our discussion being incomplete, nothing more. Totally fair!

msla 7y ago

> Note that "cast" and "coerce" are different. Python supports coercion but not casting. Casting is an operation done in static type systems where you tell the compiler "I know this has type X, but pretend it has type Y". Coercion is a run-time operation which moves data from a box of one type into a box of a new type (i.e., a new object is allocated). Right. I know this, I just call coercion "autoconversion" because the data is typically given a new form as well as a new box. Having autoconversion without casting is a sign of a strong type system, because you can't turn off the type system, you are only allowed to use it. If there's no way to autoconvert from type A to type B, that's it: You can't turn a value of type A into one of type B by hook or by crook. > I'm not sure what you mean by "the problem" here. "Problem" in the sense of our discussion being incomplete, nothing more. > Weak dynamic type systems are, in my opinion, the worst of all worlds. They provide neither compile-time checks nor runtime checks that really amount to much. I don't know why you would ever prefer a weak dynamic type system in a language. I agree with all of this. > JavaScript is essentially weak and dynamically typed. Wrong, for the reasons I went over in other posts.

DonaldPShimoda 7y ago
Ah I didn't realize I had replied to the same person in different places. Sorry about that haha. > I know this, I just call coercion "autoconversion" because the data is typically given a new form as well as a new box. Hmm interesting. I think I dislike this because coercion is not always automatic, so the "auto" part of "autoconversion" is a hang-up for me. For example, doing `int("3")` in Python is an explicit coercion, but I don't think it would qualify as an "autoconversion" (unless I'm not quite understanding your definition of that term). In the interests of clarity until I understand better, I'll continue using "coercion" and I'll specify implicit vs. explicit as needed. > Having autoconversion without casting is a sign of a strong type system, because you can't turn off the type system, you are only allowed to use it. I agree for explicit coercion, but not with implicit. If your coercion is implicit, then the user has no control over what's going on. The type system is essentially transforming values' types behind the curtain in an effort to prevent errors. This means that errors which the user might believe should be raised may not be. The type system is "weak" because it's not holding types rigidly with respect to the user's perspective. The user's perspective is key, because if we look at things from the language's perspective then almost any language could be viewed as strongly typed given the right theoretical framework. > "Problem" in the sense of our discussion being incomplete, nothing more. Totally fair!