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A comment on Pyrefly: Python type checker and language server in Rust. Parent comment

Re:Pyrefly: Python type checker and language server in Rust by parhamn on Tuesday October 14, 2025 @09:42AM (#45579952)
Whats the expected error in the example you gave? That x can't be none because it was received as a str?
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Re:Pyrefly: Python type checker and language server in Rust by wiz21c on Tuesday October 14, 2025 @10:29AM (#45580488)
isn't it perfectly valid to pass None to that function ? It's not like python enforces types at runtime nor at compile time. Right ?
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Re:Pyrefly: Python type checker and language server in Rust by Austizzle on Tuesday October 14, 2025 @10:47AM (#45580739)
It's not valid from a typing perspective, but python will let you. If you want to disregard types though then none of this matters anyway and you won't get much benefit from these tools
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Re:Pyrefly: Python type checker and language server in Rust by yesb on Tuesday October 14, 2025 @10:54AM (#45580828)
Sure, it's valid python to do that. By that logic you could also pass an int. But the context of this post is that you're using a static type checker.
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Re:Pyrefly: Python type checker and language server in Rust by robertlagrant on Tuesday October 14, 2025 @09:45AM (#45579977)
Yes, exactly. x would have to be str | None to be reachable.
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Re:Pyrefly: Python type checker and language server in Rust by pawelkobojek on Tuesday October 14, 2025 @09:45AM (#45579974)
Exactly - something along the lines of "Statement is unreachable".
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Re:Pyrefly: Python type checker and language server in Rust by boxed on Tuesday October 14, 2025 @09:44AM (#45579970)
Or that x is unused?
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