Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
0fcee100e7
Now that the elaborator supports primitive projections for recursive inductive types (#5822), enable defining recursive inductive types with the `structure` command, which was set up in #5842. Example: ```lean structure Tree where n : Nat children : Fin n → Tree def Tree.size : Tree → Nat | {n, children} => Id.run do let mut s := 0 for h : i in [0 : n] do s := s + (children ⟨i, h.2⟩).size pure s ``` Note for kernel re-implementors: recursive structures are exercising the kernel feature where primitive projections are valid for one-constructor inductive types in general, so long as the structure isn't a `Prop` and doesn't have any non-`Prop` fields, not just ones that are non-indexed and non-recursive. Closes #2512 |
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