Two Case Studies of NaN

2 days ago

Python's list equality optimization compares elements by identity first, which assumes an object always compares equal to itself, an assumption violated by NaN.
In Lua's numerical for-loops, NaN leads to unintuitive behavior because the implementation's comparison logic breaks when checking limits and steps with NaN, which is likely an oversight.
NaN's unique properties often cause programming language design choices or optimizations to fail, as seen in Python, Lua, and previously documented cases like Go map keys.

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