23 lines
737 B
Text
23 lines
737 B
Text
open nat
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inductive {u} Vec (X : Type u) : ℕ → Type u
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| nil {} : Vec 0
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| cons : X → Pi {n : nat}, Vec n → Vec (n + 1)
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namespace Vec
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def get₂ {A : Type} : Π {n : ℕ}, Vec A (succ $ succ n) → A
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| n (cons x₁ (cons x₂ xs)) := x₂
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def get₂a {A : Type} : Π {n : ℕ}, Vec A (n+2) → A
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| 0 (cons x₁ (cons x₂ xs)) := x₂
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| (n+1) (cons x₁ (cons x₂ xs)) := x₂
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def get₂b {A : Type} : Π {n : ℕ}, Vec A (n+2) → A
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| n (cons x₁ (cons x₂ xs)) := x₂
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def get₂c {A : Type} : Π {n : ℕ}, Vec A (n+2) → A
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| .(n) (@cons .(A) x₁ .(n+1) (@cons .(A) x₂ n xs)) := x₂
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def get₂d {A : Type} : Π {n : ℕ}, Vec A (n+2) → A
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| .(n) (@cons .(A) x₁ (n+1) (@cons .(A) x₂ .(n) xs)) := x₂
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end Vec
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