chore: simplify the connection between HasFresh and Infinite
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ctchou
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Jan 30, 2026
| fresh_notMem s := s.finite_toSet.infinite_compl.nonempty.choose_spec | ||
| This, in conjunction with `HasFresh.to_infinite`, characterizes `HasFresh`. -/ | ||
| noncomputable instance HasFresh.of_infinite (α : Type u) [Infinite α] : HasFresh α where | ||
| fresh s := Infinite.exists_notMem_finset s |>.choose |
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I really don't know what the preferred style is: should there be a space between |> and .?
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These are semantically different:
|>.chooseis projecting from the pipe (Lean.Parser.Term.pipeProj) and resolves toExists.choose|> .chooseis piping to Lean.Parser.Term.dotIdent, which cannot infer the meaning of.choosein this case becauseClassical.choosealso exists
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In this case, I wonder if (Infinite.exists_notMem_finset s).choose is actually clearer.
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I am fairly ambivalent, but I think this is a common enough core syntax to not be considered obfuscatory. I wrote it without thinking, not as a golfing attempt.
fmontesi
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Jan 30, 2026
chenson2018
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Jan 30, 2026
This PR adds an instance directly showing that `HasFresh` implies `Infinite`. This replaces `HasFresh.not_of_finite` which triggered a linter and is now equivalent to just `not_finite`. `HasFresh.of_infinite` is also changed to an instance with a slightly more direct definition.
arademaker
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Feb 2, 2026
…nprover#303) This PR adds an instance directly showing that `HasFresh` implies `Infinite`. This replaces `HasFresh.not_of_finite` which triggered a linter and is now equivalent to just `not_finite`. `HasFresh.of_infinite` is also changed to an instance with a slightly more direct definition.
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This PR adds an instance directly showing that
HasFreshimpliesInfinite. This replacesHasFresh.not_of_finitewhich triggered a linter and is now equivalent to justnot_finite.HasFresh.of_infiniteis also changed to an instance with a slightly more direct definition.