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I am familiar with both Python and its typing, and Rust. Obviously, Rust has ADTs, which open up a whole new class of types. However, I wouldn't call Python's t

I am familiar with both Python and its typing, and Rust. Obviously, Rust has ADTs, which open up a whole new class of types. However, I wouldn't call Python's type system weak! It's still under very active development, but making full use of it (i.e., type annotations) and the strictest settings in mypy makes for a very powerful combination. I've never felt the system was too weak; if anything, I was. There's type narrowing, warnings for not awaiting Awaitables, generics, protocols/interfaces, even whole function signatures can be lifted into the type system (ParamSpec). Dictionaries can be turned into typed versions as well, which is quite powerful. By default, it's weaker, as it's optional. Rust's isn't optional. But start a greenfield project with type annotations and you won't be disappointed, I hope. Features like ADTs will still be absent, but I feel that's an orthogonal issue to type safety etc.

meheleventyone 3y ago
A lot of people probably don’t know that Python is adding optional types FWIW. I started and stopped using Python before it was even thought about.
maxbond 3y ago
Yeah. Maybe weak is too strong a claim. I have done a lot of typed Python code fwiw. I'm certainly never going back to untyped Python for anything outside of a scripting context. "Python wasn't weak, I was" is an accurate call out, I have abandoned complex annotations in Python before because there was a bunch of cruft involved and the documentation wasn't always as straightforward as I'd have liked. The lack of ADTs (and thus a Result type) combined with the lack of exceptions as part of the function signature (like Java) make it really difficult to develop a reliable application. Maybe that's not quite a type safety issue, but it's a safety issue for sure. Digging in, it looks like people are working around this by returning exceptions, which is very clever and I hadn't thought of it before.
- diarrhea 3y ago
  > Digging in, it looks like people are working around this by returning exceptions, which is very clever and I hadn't thought of it before. Never came across that! Where did you find that? Pretty interesting. I'd call it deeply unpythonic and very surprising. It's unfortunate to not have a Result type/idiom, but IMHO faking it isn't the way to go either.
  - maxbond 3y ago
    I saw it in this Stack Overflow answer: https://stackoverflow.com/a/74192977 https://stackoverflow.com/a/74192977 I haven't given it a great deal if thought, it would probably mess up stack traces if you raised it later, which would be bad. I agree it's unpythonic, I've implemented result-like types in Python before which has worked okay. ETA: That answer links to this library, which uses a decorator technique that I think will still print a good traceback if you reraise it later (definitely will if you use `raise ... from` syntax), but I can't test it at the moment: https://github.com/alexandermalyga/poltergeist https://github.com/alexandermalyga/poltergeist I probably won't be putting this into production anytime soon but it was charming food for thought.

meheleventyone 3y ago

A lot of people probably don’t know that Python is adding optional types FWIW. I started and stopped using Python before it was even thought about.

maxbond 3y ago

Yeah. Maybe weak is too strong a claim. I have done a lot of typed Python code fwiw. I'm certainly never going back to untyped Python for anything outside of a scripting context. "Python wasn't weak, I was" is an accurate call out, I have abandoned complex annotations in Python before because there was a bunch of cruft involved and the documentation wasn't always as straightforward as I'd have liked. The lack of ADTs (and thus a Result type) combined with the lack of exceptions as part of the function signature (like Java) make it really difficult to develop a reliable application. Maybe that's not quite a type safety issue, but it's a safety issue for sure. Digging in, it looks like people are working around this by returning exceptions, which is very clever and I hadn't thought of it before.

diarrhea 3y ago
> Digging in, it looks like people are working around this by returning exceptions, which is very clever and I hadn't thought of it before. Never came across that! Where did you find that? Pretty interesting. I'd call it deeply unpythonic and very surprising. It's unfortunate to not have a Result type/idiom, but IMHO faking it isn't the way to go either.
- maxbond 3y ago
  I saw it in this Stack Overflow answer: https://stackoverflow.com/a/74192977 https://stackoverflow.com/a/74192977 I haven't given it a great deal if thought, it would probably mess up stack traces if you raised it later, which would be bad. I agree it's unpythonic, I've implemented result-like types in Python before which has worked okay. ETA: That answer links to this library, which uses a decorator technique that I think will still print a good traceback if you reraise it later (definitely will if you use `raise ... from` syntax), but I can't test it at the moment: https://github.com/alexandermalyga/poltergeist https://github.com/alexandermalyga/poltergeist I probably won't be putting this into production anytime soon but it was charming food for thought.