23 lines
415 B
Text
23 lines
415 B
Text
inductive foo : bool → Type
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| Z : foo ff
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| O : foo ff → foo tt
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| E : foo tt → foo ff
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open foo
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definition to_nat : ∀ {b}, foo b → nat
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| .(ff) Z := 0
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| .(tt) (O n) := to_nat n + 1
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| .(ff) (E n) := to_nat n + 1
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example : to_nat (E (O Z)) = 2 :=
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rfl
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example : to_nat Z = 0 :=
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rfl
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example (a : foo ff) : to_nat (O a) = to_nat a + 1 :=
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rfl
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example (a : foo tt) : to_nat (E a) = to_nat a + 1 :=
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rfl
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