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Python Performance: Why 'if not list' is 2x Faster Than Using len()
(blog.codingconfessions.com)
this post was submitted on 12 Apr 2025
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if isinstance(mylist, list) and not mylistProblem solved.
Or
if not mylist # check if list is emptyYou’re checking if
mylistis falsey. Sometimes that’s the same as checking if it’s empty, if it’s actually a list, but that’s not guaranteed.Doesn't Python treat all empty iterables as false tho? This isn't unique to python, is it? (though I'm not a programmer...just a dude who writes scripts every now and then)
Not really, generators have weird truthiness, i don't remember if they evaluate to true or false, but they cannot be checked for emptiness so they default to either always true or always false.