4 ms·

You are describing static typing. There is a well defined difference between strongly typed and statically typed.

enginaar 7y ago
Could you elaborate or point to a resource? AFAIK, term "strongly typed" is usually used to refer to that the type cannot change but I'm failing to find a well defined definition or the comparison against statically typed.
- willtim 7y ago
  The word "type" has a specific meaning in maths/logic, which is not the same as that used by the "dynamic" languages community. Professor Bob Harper of CMU would refer to Python as unityped, i.e. having a single type: https://existentialtype.wordpress.com/2011/03/19/dynamic-languages-are-static-languages/ https://existentialtype.wordpress.com/2011/03/19/dynamic-lan...
- kbp 7y ago
  Static typing means that types are figured out statically by looking at the source code, and type errors are detected then when it notices a mismatch. Dynamic typing means that types are worked out at runtime by looking at live objects when code operating on them executes. Strong typing means that types cannot be substituted for other types. In C, you can write `int x = "one"` and the char * (address of) "one" is automatically converted to an int, or in Javascript you can write 1 + "2" and a string "1" is automatically created; depending who you're talking to, either or both of these qualify as weak typing. They're both spectrums, and commonly confused with each other.
  - willtim 7y ago
    "Dynamic typing" is really just case analysis at runtime. Every static language is capable of dynamic typing, it's not some feature that statically typed languages lack. A dynamic language is really just a static language with one type.
    - kbp 7y ago
      Why aren't statically typed programs really just dynamically typed programs where all the types happen to be statically inferable?
      - willtim 7y ago
        Because most statically typed languages allow us to define our own types, add type signatures to constrain etc. Dependently typed languages also allow types to depend on values. Inference is useful, but only one aspect of static typing.
        deleted 7y ago
        [deleted]
  - enginaar 7y ago
    You're explaining static typing vs dynamic typing. I'm still failing to see how different Strong vs Static. If the only difference is "Static" means "types are figured out statically by looking at the source code" do you mean it's possible to change the type unlike strong typing? If not, can we say Static encapsulates Strong?
    - deleted 7y ago
      [deleted]
    - kbp 7y ago
      Static typing is not a superset of strong typing, they're on different axes. Strong vs weak typing (which I explained in the second paragraph) is about how strictly types need to match expected types before you get a type error. Static vs dynamic typing is about when you get a type error (during a static typechecking phase, or at runtime when you try to use a value as that type). When you say the type cannot change, that's ambiguous: do you mean the type of the value a variable holds, or the type of the value itself? In C (a statically typed language), "int x" means that x will always hold an int, but you can still assign a pointer to it, it just turns into an int (weak typing). In Python (a dynamically typed language), the variable "x" wouldn't have a type (so it could hold an int at one point and a string later), but the value it holds does, and because it's strongly typed, it would throw a type error if you attempted to use it in a place where it wanted a different type (eg, `1 + "2"` does not turn 1 into a string or "2" into an int).
      - enginaar 7y ago
        If I got this correct, you're saying strong can be compared to weak and static can be compared to dynamic. So there is no such thing as strong vs static typing comparison.
        kbp 7y ago
        Right, they describe different aspects of how types work in a language.
willtim 7y ago
My point is that your marketing is misleading. Use "strong dynamic types" if you must, but for Python, it would be more accurate to say "strongly tagged".

Could you elaborate or point to a resource? AFAIK, term "strongly typed" is usually used to refer to that the type cannot change but I'm failing to find a well defined definition or the comparison against statically typed.

willtim 7y ago
The word "type" has a specific meaning in maths/logic, which is not the same as that used by the "dynamic" languages community. Professor Bob Harper of CMU would refer to Python as unityped, i.e. having a single type: https://existentialtype.wordpress.com/2011/03/19/dynamic-languages-are-static-languages/ https://existentialtype.wordpress.com/2011/03/19/dynamic-lan...
kbp 7y ago
Static typing means that types are figured out statically by looking at the source code, and type errors are detected then when it notices a mismatch. Dynamic typing means that types are worked out at runtime by looking at live objects when code operating on them executes. Strong typing means that types cannot be substituted for other types. In C, you can write `int x = "one"` and the char * (address of) "one" is automatically converted to an int, or in Javascript you can write 1 + "2" and a string "1" is automatically created; depending who you're talking to, either or both of these qualify as weak typing. They're both spectrums, and commonly confused with each other.
- willtim 7y ago
  "Dynamic typing" is really just case analysis at runtime. Every static language is capable of dynamic typing, it's not some feature that statically typed languages lack. A dynamic language is really just a static language with one type.
  - kbp 7y ago
    Why aren't statically typed programs really just dynamically typed programs where all the types happen to be statically inferable?
    - willtim 7y ago
      Because most statically typed languages allow us to define our own types, add type signatures to constrain etc. Dependently typed languages also allow types to depend on values. Inference is useful, but only one aspect of static typing.
      - deleted 7y ago
        [deleted]
- enginaar 7y ago
  You're explaining static typing vs dynamic typing. I'm still failing to see how different Strong vs Static. If the only difference is "Static" means "types are figured out statically by looking at the source code" do you mean it's possible to change the type unlike strong typing? If not, can we say Static encapsulates Strong?
  - deleted 7y ago
    [deleted]
  - kbp 7y ago
    Static typing is not a superset of strong typing, they're on different axes. Strong vs weak typing (which I explained in the second paragraph) is about how strictly types need to match expected types before you get a type error. Static vs dynamic typing is about when you get a type error (during a static typechecking phase, or at runtime when you try to use a value as that type). When you say the type cannot change, that's ambiguous: do you mean the type of the value a variable holds, or the type of the value itself? In C (a statically typed language), "int x" means that x will always hold an int, but you can still assign a pointer to it, it just turns into an int (weak typing). In Python (a dynamically typed language), the variable "x" wouldn't have a type (so it could hold an int at one point and a string later), but the value it holds does, and because it's strongly typed, it would throw a type error if you attempted to use it in a place where it wanted a different type (eg, `1 + "2"` does not turn 1 into a string or "2" into an int).
    - enginaar 7y ago
      If I got this correct, you're saying strong can be compared to weak and static can be compared to dynamic. So there is no such thing as strong vs static typing comparison.
      - kbp 7y ago
        Right, they describe different aspects of how types work in a language.

willtim 7y ago

My point is that your marketing is misleading. Use "strong dynamic types" if you must, but for Python, it would be more accurate to say "strongly tagged".