10 lines
250 B
Text
10 lines
250 B
Text
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import data.vector
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open nat vector
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set_option pp.implicit true
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set_option pp.notation false
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definition diag {A : Type} : Π {n}, vector (vector A n) n → vector A n,
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diag nil := nil,
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diag ((a :: va) :: vs) := a :: diag (map tail vs)
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