/Prelude-v16.0.0/Optional/map

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Examples

map Natural Bool Natural/even (Some 3) ≡ Some False
map Natural Bool Natural/even (None Natural) ≡ None Bool

Source

{-
Transform an `Optional` value with a function
-}
let map
: ∀(a : Type) → ∀(b : Type) → (a → b) → Optional a → Optional b
= λ(a : Type)
→ λ(b : Type)
→ λ(f : ab)
→ λ(o : Optional a)
→ merge { Some = λ(x : a) → Some (f x), None = None b } o

let example0 = assert : map Natural Bool Natural/even (Some 3) ≡ Some False

let example1 = assert : map Natural Bool Natural/even (None Natural) ≡ None Bool

in map