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A comment on Building a full-text search engine in 150 lines of Python code (2021). Parent comment

Re:Building a full-text search engine in 150 lines of Python... by chaos_emergent on Friday January 24, 2025 @03:28AM (#42811468)
Holy shit, I’ve been writing python for 15 years and it’s the first time I’ve seen None used as an identity function. That’s nuts! How does it work under the hood? Does filter have a special case for evaluating None?
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Re:Building a full-text search engine in 150 lines of Python... by echoangle on Friday January 24, 2025 @03:31AM (#42811480)
Yes, that’s just a special case. You can’t call None as a function.

https://docs.python.org/3/library/functions.html#filter

> If function is None, the identity function is assumed, that is, all elements of iterable that are false are removed.

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