15 lines
480 B
Text
15 lines
480 B
Text
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--| Transform an `Optional` value with a function
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let map
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: ∀(a : Type) → ∀(b : Type) → (a → b) → Optional a → Optional b
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= λ(a : Type) →
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λ(b : Type) →
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λ(f : a → b) →
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λ(o : Optional a) →
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merge { Some = λ(x : a) → Some (f x), None = None b } o
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let example0 = assert : map Natural Bool Natural/even (Some 3) ≡ Some False
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let example1 = assert : map Natural Bool Natural/even (None Natural) ≡ None Bool
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in map
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