PSA: i’d like to add a mypy lint for it, but: an important rule of thumb in

@rules

is:

Never iterate over a

set

, except to sort it OR to create another

set

(or use

(Frozen)OrderedSet

in the first place).

see https://github.com/pantsbuild/pants/issues/14195#issuecomment-1114087237 for background

To understand, iterating over a set isn't bad, but iterating over it and using the result of the iteration in something that is sequenced and cached is (because of cache misses on varying sequences of the same data)?

yea. but almost everything eventually becomes a

Process

input.

We could always just yeet

set

and enforce an ordered set implementation?

they’re fine to use for membership checks: `x in myset`… it’s just iteration that’s potentially problematic.

This sounds like a caveat worth including in the Contributing section of the docs.