a00cf6330f
This PR adds a case to `Level.geq` that is present in the kernel's level `is_geq` procedure, making them consistent with one another. This came up during testing of `lean4lean`. Currently `Level.geq` differs from `level::is_geq` in the case of `max u v >= imax u v`. The elaborator function is overly pessimistic and yields `false` on this while the kernel function yields true. This comes up concretely in the `Trans` class: ```lean class Trans (r : α → β → Sort u) (s : β → γ → Sort v) (t : outParam (α → γ → Sort w)) where trans : r a b → s b c → t a c ``` The type of this class is `Sort (max (max (max (max (max (max 1 u) u_1) u_2) u_3) v) w)` (where `u_1 u_2 u_3` are the levels of `α β γ`), but if you try writing that type explicitly then the `class` command fails. Omitting the type leaves the `class` to infer the universe level (the command assumes the level is correct, and the kernel agrees it is), but including the type then the elaborator checks the level inequality with `Level.geq` and fails. --------- Co-authored-by: Kyle Miller <kmill31415@gmail.com>
36 lines
1.4 KiB
Text
36 lines
1.4 KiB
Text
/-!
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# Tests of universe constraints for inductive types
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https://github.com/leanprover/lean4/pull/2689 corrected the elaborator's `Level.geq`,
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which was missing cases that the kernel `is_geq` could handle.
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-/
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/-!
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This always worked. The universe level of `Trans₁` is inferred from the fields.
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-/
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structure Trans₁ {α : Sort a} {β : Sort b} {γ : Sort c}
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(r : α → β → Sort u) (s : β → γ → Sort v) (t : outParam (α → γ → Sort w)) where
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trans : r a b → s b c → t a c
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/-!
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Regression test: This was failing. An explicit universe invokes `Level.geq`.
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-/
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structure Trans₂ {α : Sort a} {β : Sort b} {γ : Sort c}
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(r : α → β → Sort u) (s : β → γ → Sort v) (t : outParam (α → γ → Sort w)) :
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Sort (max 1 a b c u v w) where
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trans : r a b → s b c → t a c
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/-!
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Regression test: This was failing. An explicit universe invokes `Level.geq`.
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-/
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inductive Trans₃ {α : Sort a} {β : Sort b} {γ : Sort c}
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(r : α → β → Sort u) (s : β → γ → Sort v) (t : outParam (α → γ → Sort w)) :
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Sort (max 1 a b c u v w) where
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| mk : (∀ a b c, r a b → s b c → t a c) → Trans₃ r s t
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/-!
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Regression test: This was failing due to the included `Type (max u v)`
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even though this is the inferred universe.
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-/
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inductive I (α : Type u) (Hom : α → α → Sort v) : Type (max u v) where
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| mk (id : ∀ X : α, Hom X X)
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