Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
d8accf47b3
This PR changes "structure-like" terminology to "non-recursive structure" across internal documentation, error messages, the metaprogramming API, and the kernel, to clarify Lean's type theory. A *structure* is a one-constructor inductive type with no indices — these can be created by either the `structure` or `inductive` commands — and are supported by the primitive `Expr.proj` projections. Only *non-recursive* structures have an eta conversion rule. The PR description contains the APIs that were renamed. Addresses RFC #5891, which proposed this rename. The change is motivated by the need to distinguish between `structure`-defined structures, structures, and non-recursive structures. Especially since #5783, which enabled the `structure` command to define recursive structures, "structure-like" has been easy to misunderstand. Changes: - Kernel: `is_structure_like()` -> `is_non_rec_structure()` - `Lean.isStructureLike` -> `Lean.isNonRecStructure` - `Lean.matchConstStructLike` -> `Lean.matchConstNonRecStructure` - `Lean.getStructureLikeCtor?` -> `Lean.getNonRecStructureCtor?` - `Lean.getStructureLikeNumFields` -> `Lean.getNonRecStructureNumFields` - `Lean.Expr.proj`: extended and corrected documentation (note: despite the fact that not every projection can be written as a recursor application, I left in this claim since it seems good to document a more-restrictive specification, and some users have requested the kernel be more restrictive in this way) Closes #5891 |
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