leanprover-community / leanprover-community/iris-lean

Remove custom Instance of Countable

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#669 0 comments 0 reactions 0 assignees View on GitHub

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Improvement
Dominant language
Lean
Stars
218
Forks
63
Avg merge
1d 23h
Merged PRs (30d)
22

Description

Just flagging this as something we should watch out for. We currently define our own notion of countability which is not the same as Mathlib. We should NOT provide an instance from our version of countability to Mathlib's version as this would introduce non-definitional diamonds re. List. If mathlib ends up moving countability into batteries or stdlib, we should change over to that.

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Review the repository's custom Countable definition and its relationship to Mathlib's Countable and List. Check whether Mathlib has moved countability into batteries or stdlib, while avoiding any instance bridge that could create non-definitional diamonds. Done means the project has a decided migration or monitoring plan without introducing the warned-about instance.

Written by the indexing model from the issue text.

Assessment

Domain
compilers
Issue type
Refactor
Difficulty
5/5
Estimated time
Over a week
Activity status
Active
Clarity
Needs clarification
Newbie friendliness
30/100

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