python - Why map(outer.remove, inner) does not work to remove inner from outer?

Question

This question already has answers here: question from:https://stackoverflow.com/questions/65894558/why-mapouter-remove-inner-does-not-work-to-remove-inner-from-outer

Answer 1

python has several elements of functional languages like lazy evaluation, which postpones execution until the computation result is needed. When calling

map(outer.remove, inner)

you are creating a mapping object, which will not apply dirty method remove to inner list until the computation "result" is actually demanded. Like e.g. when you put it on the list (which is immediately lost from the scope)

list(map(outer.remove, inner))

imho it`s generally a bad practice to mix functional programming and functions with side effects