/Prelude-v20.0.0/List/map.dhall

Copy path to clipboard

Transform a list by applying a function to each element

Examples

map Natural Bool Natural/even [ 2, 3, 5 ] ≡ [ True, False, False ]
map Natural Bool Natural/even ([] : List Natural) ≡ ([] : List Bool)

Source

--| Transform a list by applying a function to each element
let map
: ∀(a : Type) → ∀(b : Type) → (a → b) → List a → List b
= λ(a : Type) →
λ(b : Type) →
λ(f : ab) →
λ(xs : List a) →
List/build
b
( λ(list : Type) →
λ(cons : blistlist) →
List/fold a xs list (λ(x : a) → cons (f x))
)

let example0 =
assert
: map Natural Bool Natural/even [ 2, 3, 5 ] ≡ [ True, False, False ]

let example1 =
assert
: map Natural Bool Natural/even ([] : List Natural) ≡ ([] : List Bool)

in map