6 ms·

I think the objection is to the conflation of strong/weak with dynamic/static and it being unclear exactly what typed/untyped means, since it can refer to eithe

by js2 2y ago

I think the objection is to the conflation of strong/weak with dynamic/static and it being unclear exactly what typed/untyped means, since it can refer to either. Python has always been strongly typed at runtime (dynamic), vs say JavaScript which is relatively weakly typed at runtime. Obviously lihaoyi was referring to static/dynamic when they wrote untyped (as made clear by the reference to type annotations) but kstrauser is objecting to using the term "untyped" since that can be interpreted to mean weak typing as well, which Python is not. $0.02 anyway.

lolinder 2y ago
Strong/weak is a meaningless dichotomy that could be replaced by nice/icky while conveying the same meaning. It just distinguishes whether I, personally, believe a given language has sufficient protections against dumb programmer errors. What counts as strong or weak depends entirely on who's talking. Some will say that everything from C on is strong, others draw the line at Java, still others aren't comfortable until you get to Haskell, and then there are some who want to go even further before it's truly "strong". Typed versus untyped is, on the other hand, a rigorously defined academic distinction, and one that very clearly places pre-type-hints Python in the untyped category. That's not a bad thing—untyped isn't inherently a derogatory term—but because untyped languages have fallen out of vogue there's a huge effort to rebrand them.
- poincaredisk 2y ago
  ...but Python is obviously typed. It has types. In fact everything has a type, and even the types are of "type" type. It has type errors. Saying it's "untyped" invokes a wrong impression. Your usage is very non-standard in programmer circles. What's wrong with universally understood and well defined concepts of "statically" and "dynamically" typed languages?
  - lolinder 2y ago
    As I said in another comment [0], it depends on what definition of types we're using. But if we're going to pedantically jump down someone's throat correcting their usage (in this case OP's usage of "untyped"), we should at least use the most pedantically correct definition, which is the one used by academics who study type systems and which pointedly excludes dynamic checks. I have no problem with people using the other terminology in casual usage—I do so myself more often than not. I do have a problem with people pedantically correcting usage that is actually more correct than their preferred usage. I dislike pedantry in general, but I especially dislike incorrect pedantry. [0] https://news.ycombinator.com/item?id=42367659 https://news.ycombinator.com/item?id=42367659
  - c-cube 2y ago
    It's not "obviously" typed. Values in python have (runtime) types, sure. But contrast that with a statically typed language in which expressions (and functions) have types. Expressions in python do not have types at all (at least before annotations were added).
- jyounker 2y ago
  Strong/weak typing is very specific thing. It refers to the ability to create invalid types within a language. In strongly typed languages it is hard to defeat the type system. In weakly typed languages it is easy to defeat the type system. Python is strongly typed (hard to escape the bounds of the type system) but (traditionally) dynamically typed (types are checked at runtime). C is weakly typed (easy to escape the type system), but statically typed (types are checked at compile time).
  - lolinder 2y ago
    That is a possible definition for strongly typed, yes. It is not widespread or generally agreed upon—you'll see plenty of people use them in ways that contradict your definitions, and you won't see any serious work attempting to define them at all. Even Wikipedia doesn't [0]: > However, there is no precise technical definition of what the terms mean and different authors disagree about the implied meaning of the terms and the relative rankings of the "strength" of the type systems of mainstream programming languages. For this reason, writers who wish to write unambiguously about type systems often eschew the terms "strong typing" and "weak typing" in favor of specific expressions such as "type safety". [0] https://en.m.wikipedia.org/wiki/Strong_and_weak_typing https://en.m.wikipedia.org/wiki/Strong_and_weak_typing
- samatman 2y ago
  Untyped computation in the academic sense you refer to is untyped in the sense of Forth and assembler. The untyped lambda calculus doesn't even have numbers. Pragmatically, a language in which type errors occur is a typed language. Nor does it make sense to conflate "typed and untyped" with "statically typed and dynamically typed". These are simply very different things. Julia is an example of a dynamically typed language with a quite sophisticated type system and pervasive use of type annotations, it would be insane to call it untyped. Typescript is an example of a dynamic language which is nonetheless statically typed: because type errors in Typescript prevent the program from compiling, they're part of the static analysis of the program, not part of its dynamic runtime. The fact that it's uncommon to use untyped languages now is not a good reason to start describing certain type systems as 'untyped'! A good term for a language like annotation-free Python is unityped: it definitely has a (dynamic) type system, but the type of all variables and parameters is "any". Using this term involves typing one extra letter, and the payoff is you get to make a correct statement rather than one which is wrong. I think that's a worthwhile tradeoff.
  - lolinder 2y ago
    From Benjamin Pierce's Types and Programming Languages, which is basically the definitive work on types: > A type system is a tractable syntactic method for proving the absence of certain program behaviors by classifying phrases according to the kinds of values they compute. And later on: > A type system can be regarded as calculating a kind of static approximation to the runtime behaviors of the terms in a program. ... Terms like "dynamically typed" are arguably misnomers and should probably be replaced by "dynamically checked," but the usage is standard. The definitions you're using are the ones that he identifies as "arguably misnomers" but "standard". That is, they're fine as colloquial definitions but they are not the ones used in academic works. Academically speaking, a type system is a method of statically approximating the behavior of a computer program in order to rule out certain classes of behavior. Dynamic checks do not count. As I've said elsewhere, I don't have a problem with people using the colloquial definitions. I do have a problem with people actively correcting someone who's using the more correct academic definitions. We should have both sets in our lexicons and be understanding when someone uses one versus the other.
- js2 2y ago
  > Strong/weak is a meaningless dichotomy Strong/weak is not a dichotomy. It's a spectrum. That's why folks argue over where a language lands in the spectrum. OTOH, static (compile-time) vs dynamic (run-time) is a dichotomy. There's not really any in between. It's clear when and where typing occurs. So there's nothing to argue over. > Typed versus untyped is, on the other hand, a rigorously defined academic distinction A typed language is one that has a type system. Python has a type system. It's typed.
  - lolinder 2y ago
    Academically, no, a type system is by definition static. See the definition Benjamin Pierce gives in TAPL that I've placed in many comments in this subthread [0] and won't repeat here. Colloquially, yes, python has a type system. All I'm saying is it's unhelpful to correct someone for using the more correct definition rather than the colloquial one. Both definitions are valid, but if we're going to be pedantic we should at least use the academic definition for our pedantry. And you're correct, I should have said spectrum, but the point is still the same: even Wikipedia refuses to define "strongly" or "weakly" typed, suggesting people use terminology that isn't hopelessly muddled. [0] Here's one: https://news.ycombinator.com/item?id=42368689 https://news.ycombinator.com/item?id=42368689

by js2 2y ago

lolinder 2y ago

Strong/weak is a meaningless dichotomy that could be replaced by nice/icky while conveying the same meaning. It just distinguishes whether I, personally, believe a given language has sufficient protections against dumb programmer errors. What counts as strong or weak depends entirely on who's talking. Some will say that everything from C on is strong, others draw the line at Java, still others aren't comfortable until you get to Haskell, and then there are some who want to go even further before it's truly "strong". Typed versus untyped is, on the other hand, a rigorously defined academic distinction, and one that very clearly places pre-type-hints Python in the untyped category. That's not a bad thing—untyped isn't inherently a derogatory term—but because untyped languages have fallen out of vogue there's a huge effort to rebrand them.

poincaredisk 2y ago
...but Python is obviously typed. It has types. In fact everything has a type, and even the types are of "type" type. It has type errors. Saying it's "untyped" invokes a wrong impression. Your usage is very non-standard in programmer circles. What's wrong with universally understood and well defined concepts of "statically" and "dynamically" typed languages?
- lolinder 2y ago
  As I said in another comment [0], it depends on what definition of types we're using. But if we're going to pedantically jump down someone's throat correcting their usage (in this case OP's usage of "untyped"), we should at least use the most pedantically correct definition, which is the one used by academics who study type systems and which pointedly excludes dynamic checks. I have no problem with people using the other terminology in casual usage—I do so myself more often than not. I do have a problem with people pedantically correcting usage that is actually more correct than their preferred usage. I dislike pedantry in general, but I especially dislike incorrect pedantry. [0] https://news.ycombinator.com/item?id=42367659 https://news.ycombinator.com/item?id=42367659
- c-cube 2y ago
  It's not "obviously" typed. Values in python have (runtime) types, sure. But contrast that with a statically typed language in which expressions (and functions) have types. Expressions in python do not have types at all (at least before annotations were added).
jyounker 2y ago
Strong/weak typing is very specific thing. It refers to the ability to create invalid types within a language. In strongly typed languages it is hard to defeat the type system. In weakly typed languages it is easy to defeat the type system. Python is strongly typed (hard to escape the bounds of the type system) but (traditionally) dynamically typed (types are checked at runtime). C is weakly typed (easy to escape the type system), but statically typed (types are checked at compile time).
- lolinder 2y ago
  That is a possible definition for strongly typed, yes. It is not widespread or generally agreed upon—you'll see plenty of people use them in ways that contradict your definitions, and you won't see any serious work attempting to define them at all. Even Wikipedia doesn't [0]: > However, there is no precise technical definition of what the terms mean and different authors disagree about the implied meaning of the terms and the relative rankings of the "strength" of the type systems of mainstream programming languages. For this reason, writers who wish to write unambiguously about type systems often eschew the terms "strong typing" and "weak typing" in favor of specific expressions such as "type safety". [0] https://en.m.wikipedia.org/wiki/Strong_and_weak_typing https://en.m.wikipedia.org/wiki/Strong_and_weak_typing
samatman 2y ago
Untyped computation in the academic sense you refer to is untyped in the sense of Forth and assembler. The untyped lambda calculus doesn't even have numbers. Pragmatically, a language in which type errors occur is a typed language. Nor does it make sense to conflate "typed and untyped" with "statically typed and dynamically typed". These are simply very different things. Julia is an example of a dynamically typed language with a quite sophisticated type system and pervasive use of type annotations, it would be insane to call it untyped. Typescript is an example of a dynamic language which is nonetheless statically typed: because type errors in Typescript prevent the program from compiling, they're part of the static analysis of the program, not part of its dynamic runtime. The fact that it's uncommon to use untyped languages now is not a good reason to start describing certain type systems as 'untyped'! A good term for a language like annotation-free Python is unityped: it definitely has a (dynamic) type system, but the type of all variables and parameters is "any". Using this term involves typing one extra letter, and the payoff is you get to make a correct statement rather than one which is wrong. I think that's a worthwhile tradeoff.
- lolinder 2y ago
  From Benjamin Pierce's Types and Programming Languages, which is basically the definitive work on types: > A type system is a tractable syntactic method for proving the absence of certain program behaviors by classifying phrases according to the kinds of values they compute. And later on: > A type system can be regarded as calculating a kind of static approximation to the runtime behaviors of the terms in a program. ... Terms like "dynamically typed" are arguably misnomers and should probably be replaced by "dynamically checked," but the usage is standard. The definitions you're using are the ones that he identifies as "arguably misnomers" but "standard". That is, they're fine as colloquial definitions but they are not the ones used in academic works. Academically speaking, a type system is a method of statically approximating the behavior of a computer program in order to rule out certain classes of behavior. Dynamic checks do not count. As I've said elsewhere, I don't have a problem with people using the colloquial definitions. I do have a problem with people actively correcting someone who's using the more correct academic definitions. We should have both sets in our lexicons and be understanding when someone uses one versus the other.
js2 2y ago
> Strong/weak is a meaningless dichotomy Strong/weak is not a dichotomy. It's a spectrum. That's why folks argue over where a language lands in the spectrum. OTOH, static (compile-time) vs dynamic (run-time) is a dichotomy. There's not really any in between. It's clear when and where typing occurs. So there's nothing to argue over. > Typed versus untyped is, on the other hand, a rigorously defined academic distinction A typed language is one that has a type system. Python has a type system. It's typed.
- lolinder 2y ago
  Academically, no, a type system is by definition static. See the definition Benjamin Pierce gives in TAPL that I've placed in many comments in this subthread [0] and won't repeat here. Colloquially, yes, python has a type system. All I'm saying is it's unhelpful to correct someone for using the more correct definition rather than the colloquial one. Both definitions are valid, but if we're going to be pedantic we should at least use the academic definition for our pedantry. And you're correct, I should have said spectrum, but the point is still the same: even Wikipedia refuses to define "strongly" or "weakly" typed, suggesting people use terminology that isn't hopelessly muddled. [0] Here's one: https://news.ycombinator.com/item?id=42368689 https://news.ycombinator.com/item?id=42368689