23 lines
434 B
Text
23 lines
434 B
Text
inductive Foo : Bool → Type where
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| Z : Foo false
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| O : Foo false → Foo true
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| E : Foo true → Foo false
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open Foo
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def toNat : {b : Bool} → Foo b → Nat
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| _, Z => 0
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| _, O n => toNat n + 1
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| _, E n => toNat n + 1
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example : toNat (E (O Z)) = 2 :=
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rfl
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example : toNat Z = 0 :=
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rfl
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example (a : Foo false) : toNat (O a) = toNat a + 1 :=
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rfl
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example (a : Foo true) : toNat (E a) = toNat a + 1 :=
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rfl
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