CategoryLinter.lean`

Explanation legend Lean4 Domain Explanation Language (L4DEL)

L4DEL explanations are a separate layer. They do not change the Lean source. Intuition is explanatory prose; numbered items are a reading path; sources link the wording back to evidence.

L4DEL: Lean4 Domain Explanation Language

Annotation provenance. This overlay contains 10 curated AI-written annotations and 7190 mechanical source-derived annotations. They have not been human-reviewed as explanations; treat them as unverified and not mathematical authority. Retained generation history: The 71 original curated annotations were produced in a Claude Sonnet 5.5 session at medium effort; Claude Opus 5.5 is recorded in that session as the advisor model, not the direct author. The bulk source-derived expansion was generated mechanically from pinned source comments by tooling developed in a GPT-5.6 Sol session at ultra reasoning; GPT-5.6 Sol did not originate the quoted source prose. On 2026-10-17 the mechanically generated source-comment annotations of the Formal Conjectures, Carleson, FLT, PFR, CompFiles, Mathematics in Lean and Theorem Proving in Lean overlays were regenerated by the same generator after three corrections made in a Claude Sonnet 5.5 session: titles no longer cut a sentence inside mathematics or end on a dangling word, workflow markers are removed from the quoted prose, and declaration names follow the scanner's namespace resolution. The boilerplate step line was dropped, and comments that were only a row of dashes no longer yield annotations. No new prose was written and no human review is claimed.

Credit: The upstream authors and contributors retain credit for the project and mathematics. lean4-explainer only renders their pinned source and adds the separately disclosed explanation layer.

Project sources: Pinned project documentation, Formal Conjectures paper, arXiv v1

4 declarations, 0 contain sorry, 0 declared as axioms

The Category Linter

The categoryLinter is a linter to aid with formatting contributions to the Formal Conjectures repository by ensuring that results in a file have the appropriate tags in order to distinguish between open/already solved problems and background results/sanity checks.

Imports (2)

Imported by 2 files

def CategoryLinter.toCategory Checks if a command has the category attribute line 42 source
Source documentation
Checks if a command has the category attribute.

standard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses: Lean.TSyntax, List.cons, Lean.SyntaxNodeKind, Lean.Name.mkStr4, List.nil, Lean.Elab.Command.CommandElabM, Array
Proof uses: ite, Eq, Bool, Lean.Syntax.isOfKind, Lean.TSyntax.raw, Bool.true, Lean.Syntax, Lean.Syntax.getArg, OfNat.ofNat, Nat, Lean.Syntax.matchesNull, Option, Array.mapM, Lean.TSyntax.mk, Option.some, Array.getSepElems, Lean.Syntax.getArgs, Array.filterM, Lean.Name.mkStr2, Pure.pure and 10 more
9 instances, coercions and auxiliary constants left out.
```
def toCategory
  (stx : TSyntax ``Command.declModifiers) :
    CommandElabM (Array <| TSyntax ``attrInstance) := do
…
```
def CategoryLinter.checkNotOpenIfSorryFree Warns when a problem categorised as research open turns out to have a sorry-free proof line 63 source
Source documentation
Warns when a problem categorised as research open turns out to have a sorry-free proof.
This check used to live in the category attribute, at .afterTypeChecking, where it never fired for a theorem: proof terms elaborate asynchronously, so value? was still none. It did fire for a def, which is why the gap went unnoticed.
.afterCompilation is late enough to see the proof term in an ordinary file, but not inside a module, and every file in FormalConjecturesTest is a module. An attribute-based check therefore cannot be given a test. A linter runs once the command has finished and works in both, so the check lives here and findAsync? waits on the elaboration task.

standard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses: Lean.TSyntax, List.cons, Lean.SyntaxNodeKind, Lean.Name.mkStr4, List.nil, Lean.Syntax, Lean.Elab.Command.CommandElabM, Unit
Proof uses: Bind.bind, Lean.Elab.Modifiers, Lean.Elab.elabModifiers, StateRefT', IO.RealWorld, Lean.Elab.Command.State, EIO, Lean.Exception, Lean.Elab.Command.Context, Prod, Lean.Name, Lean.Elab.expandDeclIdCore, Lean.Environment, Lean.MonadEnv.getEnv, ite, Eq, Bool, Lean.Elab.Modifiers.isPrivate, Bool.true, Lean.mkPrivateName and 41 more
31 instances, coercions and auxiliary constants left out.
```
def checkNotOpenIfSorryFree (mods : TSyntax ``Lean.Parser.Command.declModifiers)
    (declId : Syntax) : CommandElabM Unit := do
…
```
def CategoryLinter.checkExactlyOneCategory Warns unless a carries exactly one category attribute line 91 source
Source documentation
Warns unless a carries exactly one category attribute. Returns whether it does, so the caller can go on to the checks that need one. stx is only used to place a warning when the modifiers carry no attribute list to point at.

standard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses: Lean.TSyntax, List.cons, Lean.SyntaxNodeKind, Lean.Name.mkStr4, List.nil, Lean.Syntax, Lean.Elab.Command.CommandElabM, Bool
Proof uses: Bind.bind, Array, CategoryLinter.toCategory, ite, Eq, Lean.Syntax.isOfKind, Lean.TSyntax.raw, Bool.true, Lean.Syntax.getArg, OfNat.ofNat, Nat, Lean.Syntax.matchesNull, Lean.TSyntax.mk, GT.gt, Array.size, Unit, Lean.Linter.logLintIf, linter.style.category_attribute, Function.comp, String and 13 more
17 instances, coercions and auxiliary constants left out.
```
def checkExactlyOneCategory (a : TSyntax ``Lean.Parser.Command.declModifiers) (stx : Syntax) :
    CommandElabM Bool := do
…
```
def CategoryLinter.categoryLinter The problem category linter checks that every theorem/lemma/example has been given a problem category attribute line 109 source
Source documentation
The problem category linter checks that every theorem/lemma/example has been given a problem category attribute.

standard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses: Lean.Elab.Command.Linter
Proof uses: Lean.Elab.Command.Linter.mk, Lean.withSetOptionIn, Lean.Syntax, ite, Lean.Elab.Command.CommandElabM, Unit, Eq, Bool, Lean.Syntax.isOfKind, Lean.Name.mkStr4, Bool.true, Lean.Syntax.getArg, OfNat.ofNat, Nat, cond, Bool.or, Bool.false, Lean.TSyntax, List.cons, Lean.SyntaxNodeKind and 18 more
9 instances, coercions and auxiliary constants left out.
```
def categoryLinter : Linter where
…
```