array

stdlib/core/array.hk: fixed-size contiguous numeric arrays.

Array<T> is narrower than List<T>: T is one of f64, f32, i64 or i32, elements are stored unboxed at their exact width, and the size never changes in place. set follows functional-but-in-place (FBIP) semantics: a unique array reuses its buffer; a shared array is copied before the write; aliases continue to observe the old value.

ArrayElement

trait ArrayElement

The closed element set and its private runtime representation witness. A bound on every constructor makes Array<string> and other boxed element kinds a static type error; no dynamic rejection is needed.

arraykind

def _array_kind() -> i32

impl ArrayElement<f64>

arraykind

def _array_kind() -> i32

@no-doctest: private representation witness

impl ArrayElement<f32>

arraykind

def _array_kind() -> i32

@no-doctest: private representation witness

impl ArrayElement<i64>

arraykind

def _array_kind() -> i32

@no-doctest: private representation witness

impl ArrayElement<i32>

arraykind

def _array_kind() -> i32

@no-doctest: private representation witness

Array

type Array<T>
end

impl<T: ArrayElement> Array<T>

filled

def filled(n: int, x: T) -> Array<T>

A fixed-size array containing n copies of x. A count of zero or less produces an empty array.

xs: Array<i32> = Array.filled(3, 7i32)
xs.length => 3
xs.get(2) => Some(7i32)

from_list

def from_list(xs: List<T>) -> Array<T>

Copy a list into one contiguous array, preserving order.

xs: List<i64> = List.empty().append(2i64).append(4i64)
Array.from_list(xs).get_or(1, 0i64) => 4i64

get

def get(self, i: i64) -> Option<T>

The element at i, or None for a negative or past-the-end index.

xs: Array<f64> = Array.filled(2, 1.5f64)
match xs.get(0)
  Some(_) -> 1
  None -> 0
end => 1

get_or

def get_or(self, i: i64, fallback: T) -> T

The element at i, or fallback when it is out of bounds. This avoids allocating the Some wrapper in tight numeric loops.

xs: Array<i32> = Array.filled(2, 9i32)
xs.get_or(7, 3i32) => 3i32

set

def set(self, i: i64, x: T) -> Array<T>

Return the array with index i replaced by x. A unique receiver is updated in place; a shared receiver is copied first. An out-of-bounds index returns the receiver unchanged.

before: Array<i32> = Array.filled(2, 1i32)
after = before.set(1, 8i32)
before.get_or(1, 0i32) => 1i32
after.get_or(1, 0i32)  => 8i32

copy_resize

def copy_resize(self, n: int, fill: T) -> Array<T>

Copy into a new fixed size, preserving the common prefix and filling a grown tail with fill.

xs: Array<i64> = Array.filled(2, 5i64)
ys = xs.copy_resize(4, 9i64)
ys.get_or(3, 0i64) => 9i64

impl<T> Array<T>

length

prop length(self) -> i64

The number of elements.

Array.filled(4, 0.0f32).length => 4

_filled

def _filled(kind: i32, n: int, x: T) -> Array<T>

@no-doctest: private representation-bearing constructor

fromlist

def _from_list(kind: i32, xs: List<T>) -> Array<T>

@no-doctest: private representation-bearing constructor

_get

def _get(self, kind: i32, i: i64) -> Option<T>

@no-doctest: private representation-bearing read

getor

def _get_or(self, kind: i32, i: i64, fallback: T) -> T

@no-doctest: private representation-bearing read

_set

def _set(self, kind: i32, i: i64, x: T) -> Array<T>

@no-doctest: private representation-bearing update

copyresize

def _copy_resize(self, kind: i32, n: int, fill: T) -> Array<T>

@no-doctest: private representation-bearing resize