🔒 equality of two lists by function

[balmy vortex]

I've got two lists, and I'd like to check that they are equal according to some custom lambda. how can I do this?

[sweet bison]

@balmy vortex

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[torpid field]

call the lambda with both lists as arguments

[balmy vortex]

sorry, can you please help me with the syntax?
given as: List[Foo], bs: List[Foo] and a method matches(other: Foo) -> bool defined on Foo, how would I write this?

I see all(map(Foo.matches, as, bs))

would work

[torpid field]

is other supposed to be a method on Foo?

[balmy vortex]

if I also check len(as) == len(bs)

[torpid field]

It should be accepting self

[balmy vortex]

yes it is

so len(as) == len(bs) and all(map(Foo.matches, as, bs)) would work, but (coming from other languages), it feels like there's an existing way to do this

[torpid field]

i believe as == bs should work if you override __eq__ on Foo

[balmy vortex]

there's really nothing else, huh?

[torpid field]

are you expecting something specific?

[balmy vortex]

yes. I expect any reasonable language to give me a compare_by function for iterables

thank you for the help

[torpid field]

!e @balmy vortex

class Foo:
  def __init__(self, value: int) -> None:
    self.value = value
  def __eq__(self, other) -> bool:
    if isinstance(other, Foo):
      return self.value == other.value
    return False

xs = [Foo(1), Foo(2)]
ys = [Foo(1), Foo(2)]
print(xs == ys)

[sweet bison]

:white_check_mark: Your 3.12 eval job has completed with return code 0.

True

[balmy vortex]

that assumes I control the definition of Foo and that I want to define general equality as matches

[torpid field]

right. otherwise we don't have a compare_by because genexps are flexible enough to cover that usecase

[balmy vortex]

I'm going to have to get used to this way of doing things.
this is my language unfamiliarity + personal taste speaking here.

I'm sure I'll get over it 👍

[sweet bison]

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