38 lines
1 KiB
Text
38 lines
1 KiB
Text
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--| Apply a function across a list, keeping only the `Some` results.
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let List/unpackOptionals =
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missing
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sha256:0cbaa920f429cf7fc3907f8a9143203fe948883913560e6e1043223e6b3d05e4
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? ./unpackOptionals.dhall
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let List/map =
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missing
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sha256:dd845ffb4568d40327f2a817eb42d1c6138b929ca758d50bc33112ef3c885680
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? ./map.dhall
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let mapMaybe
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: ∀(a : Type) → ∀(b : Type) → (a → Optional b) → List a → List b
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= λ(a : Type) →
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λ(b : Type) →
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λ(f : a → Optional b) →
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λ(xs : List a) →
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List/unpackOptionals b (List/map a (Optional b) f xs)
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let property =
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λ(a : Type) →
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λ(b : Type) →
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λ(f : a → Optional b) →
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assert : mapMaybe a b f ([] : List a) ≡ ([] : List b)
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let example0 =
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assert
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: mapMaybe
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Natural
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Text
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( λ(n : Natural) →
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if Natural/isZero n then None Text else Some (Natural/show n)
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)
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[ 0, 1, 2, 3 ]
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≡ [ "1", "2", "3" ]
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in mapMaybe
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