98e4b2882f
This PR migrates usages of `Std.Range` to the new polymorphic ranges. This PR unfortunately increases the transitive imports for frequently-used parts of `Init` because the ranges now rely on iterators in order to provide their functionality for types other than `Nat`. However, iteration over ranges in compiled code is as efficient as before in the examples I checked. This is because of a special `IteratorLoop` implementation provided in the PR for this purpose. There were two issues that were uncovered during migration: * In `IndPredBelow.lean`, migrating the last remaining range causes `compilerTest1.lean` to break. I have minimized the issue and came to the conclusion it's a compiler bug. Therefore, I have not replaced said old range usage yet (see #9186). * In `BRecOn.lean`, we are publicly importing the ranges. Making this import private should theoretically work, but there seems to be a problem with the module system, causing the build to panic later in `Init.Data.Grind.Poly` (see #9185). * In `FuzzyMatching.lean`, inlining fails with the new ranges, which would have led to significant slowdown. Therefore, I have not migrated this file either.
37 lines
1.4 KiB
Text
37 lines
1.4 KiB
Text
import Lean
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/-!
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#2564. `match` reduction currently has some special cases.
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When combined with nonlinear functions like `List.insert` below,
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it is crucial to preserve sharing during reduction. -/
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section decidability_instances
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variable {α : Type} {p : α → Prop} [DecidablePred p]
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instance decidableBex : ∀ (l : List α), Decidable (∃ x, x ∈ l → p x)
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| [] => isFalse sorry
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| x::xs =>
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match ‹DecidablePred p› x with
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| isTrue h₁ => isTrue sorry
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| isFalse h₁ => match decidableBex xs with
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| isTrue h₂ => isTrue sorry
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| isFalse h₂ => isFalse sorry
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instance decidableBall (l : List α) : Decidable (∀ x, x ∈ l → p x) :=
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match (inferInstance : Decidable <| ∃ x, x ∈ l → ¬ p x) with
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| isFalse h => isTrue $ fun x hx => match ‹DecidablePred p› x with
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| isTrue h' => h'
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| isFalse h' => False.elim $ h sorry
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| isTrue h => isFalse sorry
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end decidability_instances
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def parts : List (List Nat) := List.insert ([1, 1, 0, 0]) <| List.insert ([0, 0, 1, 1]) <|
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List.insert ([1, 0, 0, 1]) <| List.insert ([1, 1, 1, 0]) <| List.insert ([1, 0, 0, 0]) <|
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List.insert [1, 2, 3, 4] <| List.insert [5, 6, 7, 8] []
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#eval show Lean.Elab.Command.CommandElabM _ from
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for _ in *...(10 : Nat) do
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Lean.Elab.Command.elabCommand (←
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`(example : ∀ (x) (_ : x ∈ parts) (y) (_ : y ∈ parts), x ++ y ∉ parts := by decide))
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