array

Types

A JavaScript array, in Gleam!

Unlike most data structures in Gleam this one is mutable.

pub external type Array(element)

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pub external fn fold(
  over: Array(e),
  from: a,
  with: fn(a, e) -> a,
) -> a

Reduces a list of elements into a single value by calling a given function on each element, going from left to right.

fold(from_list([1, 2, 3]), 0, add) is the equivalent of add(add(add(0, 1), 2), 3).

Runs in linear time.

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pub external fn fold_right(
  over: Array(e),
  from: a,
  with: fn(a, e) -> a,
) -> a

Reduces a list of elements into a single value by calling a given function on each element, going from right to left.

fold_right(from_list([1, 2, 3]), 0, add) is the equivalent of add(add(add(0, 3), 2), 1).

Runs in linear time.

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pub external fn from_list(List(element)) -> Array(element)

Convert a Gleam list to a JavaScript array.

Runs in linear time.

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pub external fn get(Array(e), Int) -> Result(e, Nil)

Get the element at the given index.

> get(from_list([2, 4, 6]), 1)
Ok(4)

> get(from_list([2, 4, 6]), 4)
Error(Nil)

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pub external fn map(Array(a), with: fn(a) -> b) -> Array(b)

Returns a new array containing only the elements of the first array after the function has been applied to each one.

Runs in linear time.

> map(from_list([2, 4, 6]), fn(x) { x * 2 })
from_list([4, 8, 12])

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pub external fn size(Array(element)) -> Int

Get the number of elements in the array.

Runs in constant time.

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pub external fn to_list(Array(element)) -> List(element)

Convert a JavaScript array to a Gleam list.

Runs in linear time.