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I love how simple and forgiving Python is for small projects. The "trailing comma creates a tuple" situation comes out of, as far as I can tell, a desire to cre

I love how simple and forgiving Python is for small projects. The "trailing comma creates a tuple" situation comes out of, as far as I can tell, a desire to create maximally convenient syntax in the scenarios where tuples are intended. I think that's great for small code! I just wish that the core team would take that same zeal for a "pythonic" experience with small code and use it to develop more scaled-up systems for dealing with larger code bases. My idea is to enforce strong pre-conditions on function calls using type hints, but I am sure there are other ways to do it.

iooi 5y ago
If you use mypy (as anyone should for any non-hobby Python usage) then Python has one of the strongest type systems available. Optional types, generics, "Any" escape hatches, everything you could want.
- aeturnum 5y ago
  mypy is a great project and I agree that basically every project at scale should use it. However, I think you're wrong about the strength of the Python type system and what a good type system can "get" you. I think mypy both does an amazing job at static checking and that more powerful type systems go far beyond static checks and into changing how you structure and write code. The newly introduced "structural pattern matching" they just introduced[1] is an example of the kind of feature that could be usefully expanded by making type a first-class part of the Python runtime. Again - the dynamism of Python means teams can write amazing extensions to Python (like mypy), but that isn't a replacement for the core team having a plan for how they think typing information should be used at runtime. Their current answer seems to be "nothing," which disappoints me. [1] https://www.python.org/dev/peps/pep-0622/ https://www.python.org/dev/peps/pep-0622/
- yawaramin 5y ago
  Would mypy have caught any of the issues highlighted in the article?
  - Too 5y ago
    No. Mypy only cares about types, it would only have been caught if something was expecting tuple of certain length, otherwise not. The problem in the article is more related to syntax, not types, with the problem that both forms are valid syntax with different but still very similar outcome. Pylint on the other hand can find it with implicit-str-concat check enabled.
- jen20 5y ago
  > one of the strongest type systems available. This is simply not true - Python with mypy isn’t even as strong as Typescript, let alone Rust, F#, Haskell and so forth.
DangitBobby 5y ago
For a language that is so incredibly picky about it's whitespace rules, it's a little laissez faire on the string-concatentation/tuple syntax side. I say this as someone who loves python and uses it extensively.
trulyme 5y ago
The "trailing comma creates a tuple" bug actually comes from a disconnect between what people think defines a tuple (parenthesis) and what really does (comma). I always put parenthesis around a tuple for clarity.
- tayo42 5y ago
  whats the reason for allowing like foo, to be a tuple? why not make this a syntax error? is there a use for single value tuples?
  - trulyme 5y ago
    Yes, single tuple values are useful for example for passing to a function which expects a tuple (because it might expect zero, one or multiple values). The thing is, your example is the way tuple should be defined. The parenthesis are merely allowed (and ignored). Why? I see this as a mistake of language creators. But to be fair, it is difficult to make a perfect language (or anything really), and Python is pretty close imho.

iooi 5y ago

If you use mypy (as anyone should for any non-hobby Python usage) then Python has one of the strongest type systems available. Optional types, generics, "Any" escape hatches, everything you could want.

aeturnum 5y ago
mypy is a great project and I agree that basically every project at scale should use it. However, I think you're wrong about the strength of the Python type system and what a good type system can "get" you. I think mypy both does an amazing job at static checking and that more powerful type systems go far beyond static checks and into changing how you structure and write code. The newly introduced "structural pattern matching" they just introduced[1] is an example of the kind of feature that could be usefully expanded by making type a first-class part of the Python runtime. Again - the dynamism of Python means teams can write amazing extensions to Python (like mypy), but that isn't a replacement for the core team having a plan for how they think typing information should be used at runtime. Their current answer seems to be "nothing," which disappoints me. [1] https://www.python.org/dev/peps/pep-0622/ https://www.python.org/dev/peps/pep-0622/
yawaramin 5y ago
Would mypy have caught any of the issues highlighted in the article?
- Too 5y ago
  No. Mypy only cares about types, it would only have been caught if something was expecting tuple of certain length, otherwise not. The problem in the article is more related to syntax, not types, with the problem that both forms are valid syntax with different but still very similar outcome. Pylint on the other hand can find it with implicit-str-concat check enabled.
jen20 5y ago
> one of the strongest type systems available. This is simply not true - Python with mypy isn’t even as strong as Typescript, let alone Rust, F#, Haskell and so forth.

DangitBobby 5y ago

For a language that is so incredibly picky about it's whitespace rules, it's a little laissez faire on the string-concatentation/tuple syntax side. I say this as someone who loves python and uses it extensively.

trulyme 5y ago

The "trailing comma creates a tuple" bug actually comes from a disconnect between what people think defines a tuple (parenthesis) and what really does (comma). I always put parenthesis around a tuple for clarity.

tayo42 5y ago
whats the reason for allowing like foo, to be a tuple? why not make this a syntax error? is there a use for single value tuples?
- trulyme 5y ago
  Yes, single tuple values are useful for example for passing to a function which expects a tuple (because it might expect zero, one or multiple values). The thing is, your example is the way tuple should be defined. The parenthesis are merely allowed (and ignored). Why? I see this as a mistake of language creators. But to be fair, it is difficult to make a perfect language (or anything really), and Python is pretty close imho.