28 lines
657 B
Text
28 lines
657 B
Text
class HasElems (α : Type) : Type := (elems : Array α)
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def elems (α : Type) [HasElems α] : Array α := HasElems.elems
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inductive Foo : Type
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| mk1 : Bool → Foo
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| mk2 : Bool → Foo
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open Foo
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instance BoolElems : HasElems Bool := ⟨#[false, true]⟩
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instance FooElems : HasElems Foo := ⟨(elems Bool).map mk1 ++ (elems Bool).map mk2⟩
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def fooRepr (foo : Foo) :=
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match foo with
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| mk1 b => f!"OH {b}"
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| mk2 b => f!"DR {b}"
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instance : Repr Foo := ⟨fun s _ => fooRepr s⟩
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#eval elems Foo
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#eval #[false, true].map Foo.mk1
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def Foo.toBool : Foo → Bool
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| Foo.mk1 b => b
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| Foo.mk2 b => b
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#eval #[Foo.mk1 false, Foo.mk2 true].map Foo.toBool
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