4 ms·

No, but let me clarify. Bolting on a form of type checking to a weakly typed language seems orthogonal to the nature of a language like Python. If you find your

• swhipple 11y ago
  Static typing is considered unpythonic, but the typecheck library is closer to a sanity-checking model (like using assert). The advantage is that instead of the checks being in the body, they can be moved to the function header. It supports things such as checking ranges or regex matches, rather than just object types. Even if people are only using it as a shim for what could be static typechecking, I think there's something to say about the practicality of it existing, if only for the reason that their ecosystem might already be Python-based.
• dangirsh 11y ago
  Though I agree with your sentiment, I must mention that there is nothing "weak" about Python's type system. You likely meant "dynamic", not "weak". See here: wiki.python.org/moin/Why%20is%20Python%20a%20dynamic%20language%20and%20also%20a%20strongly%20typed%20language
  • aapycgarb 11y ago
    Python's type system is weak whether they self-identify that way or not. Types are implicitly converted in a variety of cases, notably True-ness. Meanwhile, runtime type identity is kind of meaningless; classes and individual objects can have their behavior meaningfully changed at runtime. The most you can say about any variable in Python is that it is a descendant of 'object' or else some primitive type.
    • Veedrac 11y ago
      If Python's `if` is weakly typed, then Rust's `for` and `.` are weakly typed. Few would say that, though.
      • cma 11y ago
        One place where Python is pretty weakly typed is going the other way, where it accepts things like: true + true * 2 - false / true, even outside of if statements. I've definitely been bitten by this before, accidentally passing in a book parameter instead of an int, and having some math work initially and then blow up months later. Knuth argues against this kind of implicit bool to integer conversion in Concrete Mathematics.
        • ubernostrum 11y ago
          Nitpick: this isn't an implicit conversion. There's a lot of history of languages without a real boolean type using integer 0 and 1 as the sentinel values indicating false-ness and true-ness. And Python, in a nod to that, implements bool as a subclass of int, of which only two instances can ever exist (with False having a value of 0 and True having a value of 1). So this isn't weak typing -- isinstance(True, int) is True in Python, and operations like the ones you're mentioning work because of that, for the same reason any other subclass of int would work.
          • cma 11y ago
            Interesting, so technically isn't weak typing, but in practice to me it is a distinction without a difference. You could make int a subtype of string, and allow things like "1" + 1 == "11" and end up with many of the same problems of weakly typed languages.
            • ubernostrum 11y ago
              Well, there's also ancient-history stuff going on here in that Python originally didn't have a boolean type, which mean using integer 0 and 1 was the standard practice. "True" and "False" as aliases for integer 1 and 0 were added in 2002, and the actual boolean type -- implemented as a subclass of int since that got automatic compatibility with existing code using integer values -- was added in 2003.
  • reeboo 11y ago
    Yep, thanks.
    • deleted 11y ago
      [deleted]
• rattray 11y ago
  I agree with everything you said here. Personally, I wish this had been your original post. It seems like a helpful jumping-off point for constructive conversation.