43 lines
1.2 KiB
Text
43 lines
1.2 KiB
Text
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{-|
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Generate a list of the specified length given a seed value and transition
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function
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-}
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let iterate
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: Natural → ∀(a : Type) → (a → a) → a → List a
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= λ(n : Natural) →
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λ(a : Type) →
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λ(f : a → a) →
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λ(x : a) →
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List/build
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a
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( λ(list : Type) →
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λ(cons : a → list → list) →
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List/fold
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{ index : Natural, value : {} }
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( List/indexed
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{}
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( List/build
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{}
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( λ(list : Type) →
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λ(cons : {} → list → list) →
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Natural/fold n list (cons {=})
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)
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)
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)
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list
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( λ(y : { index : Natural, value : {} }) →
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cons (Natural/fold y.index a f x)
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)
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)
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let example0 =
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assert
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: iterate 10 Natural (λ(x : Natural) → x * 2) 1
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≡ [ 1, 2, 4, 8, 16, 32, 64, 128, 256, 512 ]
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let example1 =
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assert
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: iterate 0 Natural (λ(x : Natural) → x * 2) 1 ≡ ([] : List Natural)
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in iterate
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