PHP went with runtime typechecking, and it isn't pretty. The type system is much less powerful than Python's because it's really hard to add complex runtime checks to an already existing dynamic language. You can make a function check whether its argument is an array, but you can't make it check whether it's, say, an array of integers, because that would require walking through the entire array, or making every array do expensive bookkeeping in case it's needed later.
If you want more complex types you have to resort to phpdoc annotations, which are only useful for offline checkers, like Python's.
When I wrote PHP we used Psalm for offline typechecking. Between that and PhpStorm the runtime checks didn't add a lot of value, and they even made mocking a lot harder at times.
On the other hand I imagine runtime checks are more useful for legacy codebases that are too messy for static analysis. I didn't work on those.
And type hints have been designed with this in mind. It will stay that way.
If this is feature makes you unhappy, Python will make you unhappy. It's important to know what are the values that are important to you and chose your toolbox accordingly.
Couldn't a Python interpreter enforce type checking and raise errors whenever a type doesn't match? I'd be happy to use such an interpreter in many scenarios.
Or you could use Java which it seems is what you wanted to use in the first place and leave Python alone.
If you do it differently, you are not implementing python.
When you’ve worked on a sufficiently large and complex code base maybe you’ll understand.
Edit: coded in python for > 10 years. I prefer it over other languages, warts and all.
This assumes:
- the dev is thinking about the API
- the dev has the knowledge and experience to do it
- the dev has the resource/constraints that allow to do so
- dev has an interest in doing so
- this is a good investment for that particular project
Thinking in black and white does not make for good language design.
I'm glad Guido designed Python and said no to so many requests to make it no Python. Because he sure been pressured to.
> When you’ve worked on a sufficiently large and complex code base maybe you’ll understand.
I do.
I also understand Python projects that have a favorable cost/benefit ratio for type hints are not that many.
When you're used to hammer you see everything as a nail, and people loving a specific language feature tend to want it everywhere.
A huge number of dev in the Python community are not professional nor even experienced programmers. And a equally big number of projects have a size or a nature that makes type hint a bad value.
When you’ve worked on a sufficiently diverse project base maybe you’ll understand.
Or when I'm doing data wrangling in jupyter and I never use type hints cause it's all just REPL rapid prototyping and I get autocomplete from the objects.
It's good for checking the internal logic, but being optional is important in the python context.
You can enforce typechecking of your code on the CI with a tool like `mypy` if you want additional safety. But you'll never get the same guarantees you'd get in OCaml or Rust. It's a tradeoff between flexibility and safety.
Python is not Java. It does not enforce type annotations by design. It's not a weakness.
There’s nothing to stop calling functions with incorrect datatypes at runtime and I’d consider this one of the single biggest weaknesses of python right now