Programmer Humor @lemmy.ml renzev @lemmy.world 6 mo. ago

Python is great, but stuff like this just drives me up the wall

Explanation: Python is a programming language. Numpy is a library for python that makes it possible to run large computations much faster than in native python. In order to make that possible, it needs to keep its own set of data types that are different from python's native datatypes, which means you now have two different bool types and two different sets of True and False. Lovely.

Mypy is a type checker for python (python supports static typing, but doesn't actually enforce it). Mypy treats numpy's bool_ and python's native bool as incompatible types, leading to the asinine error message above. Mypy is "technically" correct, since they are two completely different classes. But in practice, there is little functional difference between bool and bool_. So you have to do dumb workarounds like declaring every bool values as bool | np.bool_ or casting bool_ down to bool. Ugh. Both numpy and mypy declared this issue a WONTFIX. Lovely.

You're viewing a single thread.

61 comments

So you have to do dumb workarounds like declaring every bool values as bool | np.bool_ or casting bool_ down to bool.

these dumb workarounds prevent you from shooting yourself on the foot and not allowing JS-level shit like "1" + 2 === "12"
- The JS thing makes perfect sense though,
  
  "1" is a string. You declared its type by using quotes. myString = "1" in a dynamically typed language is identical to writing string myString = "1" in a statically typed language. You declare it in the symbols used to write it instead of having to manually write out string every single time.
  
  2 is an integer. You know this because you used neither quotes nor a decimal place surrounding it. This is also explicit.
  
  "1" + 2, if your interpreter is working correctly, should do the following
  
  identify the operands from left to right, including their types.
  
  note that the very first operand in the list is a string type as you explicitly declared it as such by putting it in quotes.
  
  cast the following operands to string if they are not already.
  
  use the string addition method to add operands together (in this case, this means concatenation).
  
  In the example you provided, "1" + 2 is equivalent to "1" + "2", but you're making the interpreter do more work.
  
  QED: "1" + 2 should, in fact, === "12", and your lack of ability to handle a language where you declare types by symbols rather than spending extra effort writing the type out as a full english word is your own shortcoming. Learn to declare and handle types in dynamic languages better, don't blame your own misgivings on the language.
  
  Signed, a software engineer.
  
  TypeError is also a correct response, though, and I think many folks would say makes more sense. Is an unnecessary footgun
- Well, C has implicit casts, and it's not that weird (although results in some interesting bugs in certain circumstances). Python is also funny from time to time, albeit due to different reasons (e.g. -5**2 is apparently -25 because of the order of operations)
  
  I don't see how your example is 'funny'. That's what you expect to get. -5² is -25. (-5)² = 25.
  
  And how's that different from js's "1" + 2? One can always convert a number to string, and only sometimes -- a string to a number, so it's pretty logical to go with the former.
  
  -5**2 is apparently -25 because of the order of operations)
  
  Which is correct
  
  Well, the link doesn't load for me, so if that's smth related to python and not a justification of the behavior from math's pov, I know that's expected. Hence,
  
  because of the order of operations
  
  But just as well is "1" + 2.
  
  Well, the link doesn’t load for me
  
  Yeah, they're doing an upgrade right now. Yes, it's the Maths explanation - -25 is the correct answer.
- "1" + 2 === "12" is not unique to JS (sans the requirement for the third equals sign), it's a common feature of multiple strongly typed languages. imho it's fine.
  
  EDIT: I did some testing:
  
  What it works in:
  
  JS
  
  TS
  
  Java
  
  C#
  
  C++
  
  Kotlin
  
  Groovy
  
  Scala
  
  PowerShell
  
  What produces a number, instead of a string:
  
  PHP
  
  SQL
  
  Perl
  
  VB
  
  Lua
  
  What it doesn't work in:
  
  R
  
  C
  
  Go
  
  Swift
  
  Rust
  
  Python
  
  Pascal
  
  Ruby
  
  Objective C
  
  Julia
  
  Fortran
  
  Ada
  
  Dart
  
  D
  
  Elixir
  
  And MATLAB appears to produce 51, wtf idk
  
  And MATLAB appears to produce 51, wtf idk
  
  The numeric value of the '1' character (the ASCII code / Unicode code point representing the digit) is 49. Add 2 to it and you get 51.
  
  C (and several related languages) will do the same if you evaluate '1' + 2.
  
  Oh that makes sense. I didn't consider it might be treated as a char

You've viewed 61 comments.