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Fix "Not a structure name" error for makeLenses #1

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Merged
paulcadman merged 2 commits into from
Jul 12, 2026
Merged

Fix "Not a structure name" error for makeLenses #1

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61c8c09
Update to lean v4.30.0
i-love-lean Jul 1, 2026
ce4f3b5
Fix "Not a structure name" error for makeLenses
i-love-lean Jul 1, 2026
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9 changes: 3 additions & 6 deletions Lens/Elab.lean
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Original file line number Diff line number Diff line change
Expand Up @@ -21,12 +21,9 @@ elab "makeLenses" structIdent:ident : command => do
let fieldNameIdent := mkIdent field.fieldName
let some decl := env.find? (field.projFn)
| throwErrorAt structIdent s!"Could not find project function {field.projFn}"
let (some fieldTypeName, some fieldTypeArgs) := (← liftTermElabM (liftMetaM (
forallTelescope decl.type fun _ body
=> pure (body.getAppFn.constName?, body.getAppArgs.mapM (·.constName?)))))
| throwErrorAt structIdent "Not a structure name"
let d ← fieldTypeArgs.mapM fun argName => `($(mkIdent argName))
let fieldTypeNameIdent := Syntax.mkCApp fieldTypeName d
let fieldTypeNameIdent : Term ← liftTermElabM <| liftMetaM <|
forallTelescope decl.type fun _ body =>
Lean.PrettyPrinter.delab body
let lensName := mkIdent field.fieldName
let newVal := mkIdent <| Name.mkSimple "newVal"
let l ←
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2 changes: 1 addition & 1 deletion lean-toolchain
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@@ -1 +1 @@
leanprover/lean4:v4.28.0
leanprover/lean4:v4.30.0
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