[chisquared]

Huh, is this what Nix users mean by “impure”?

If so, then it makes so much more sense to me now.

[rgoulter]

Yes, but 'pure' might mean different things at different levels.

In a programming language, 'pure' would just refer to "function where you get the same output from the same input; no side effects".

In parent's case, there was an 'impurity' such that the package is meaningfully different depending on the machine it was built on.