07645775e6
This PR adds decidable equality to `DHashMap`/`HashMap`/`HashSet` and their extensional variants. Stacked on top of #11266.
24 lines
528 B
Text
24 lines
528 B
Text
import Std.Data.ExtHashSet
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open Std
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@[ext]
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structure A where
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a : Nat
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b : Nat
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deriving Hashable
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instance : BEq A where
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beq x y := x.b == y.b && x.a == y.a
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@[simp]
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theorem A.beq_eq {x y : A} : (x == y) = (x.b == y.b && x.a == y.a) := rfl
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instance : LawfulBEq A where
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rfl {x} := by simp
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eq_of_beq {x y} := by grind [A.beq_eq, A.ext]
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instance : DecidableEq A :=
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fun x y => by simp [A.ext_iff]; infer_instance
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example : Decidable (ExtHashSet.ofList [A.mk 1 2] = ExtHashSet.ofList [A.mk 1 2]) := by
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infer_instance
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