Why is suffix_union so complicated? - Githubissues

conda / conda-lock

Lightweight lockfile for conda environments

https://conda.github.io/conda-lock/

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Why is suffix_union so complicated? #530

Closed maresb closed 8 months ago

maresb commented 8 months ago

What happened?

I'm having a very difficult time understanding how suffix_union works. It seems to me like it should be simpler.

Maybe first we should define prefix_union, and then suffix_union would be the reverse of prefix_union with all the arguments reversed.

Now I think prefix_union should be:

Loop over n=0...inf
Take the n-th element from each sequence that has an n-th element
In case no sequence contains an n-th element, terminate with success
Check that all the n-th elements are all equal
Append the n-th element to the result and continue looping

In particular, I don't see why we should have SupportsRichComparisonT.

Context: I'm trying to review #529.

Attn: @mariusvniekerk, @jacksmith15

maresb commented 8 months ago

Probably for implementation it's simpler to flip the order of iteration: the outer loop should be over sequences, the inner loop should be over the elements of the outer-selected sequence, and the result should be a list containing the currently-largest prefix sequence.