leanprover / leanprover/lean4

The `!` suffix

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P-low refactoring
Dominant language
Lean
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Merged PRs (30d)
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Description

Andrew Kent pointed out we were using the ! for both macros and functions that may panic at runtime.
We decided to use it only for functions that panic, and have started making the changes, but we still have to-do items.

  • The string interpolation notations are still using !.
  • Some functions that may panic at runtime still don't have !.
  • Add a[i]! notation for array access that may panic at runtime

Contributor guide

Open the contributing guide

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

Start by reviewing the existing string interpolation notations and the functions that can panic at runtime, then compare their current use of ! with the issue's rule. Done means interpolation no longer uses ! as a macro marker, all relevant panicking functions use it, and array access supports a[i]!.

Written by the indexing model from the issue text.

Assessment

Domain
compilers
Issue type
Refactor
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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