KeyedIterable

:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::

Represents any entity that can be iterated over using something like foreach

The entity is required to have a key in addition to values.

KeyedIterable does not include arrays.

Guides

• Introduction
• Interfaces

Interface Synopsis

namespace HH;

interface KeyedIterable implements Iterable<Tv>, KeyedTraversable<Tk, Tv> {...}

Public Methods

• ->concat<Tu super Tv>(Traversable<Tu> $traversable): Iterable<Tu>
  Returns an Iterable that is the concatenation of the values of the current KeyedIterable and the values of the provided Traversable
• ->filter((function(Tv): bool) $fn): KeyedIterable<Tk, Tv>
  Returns a KeyedIterable containing the values of the current KeyedIterable that meet a supplied condition
• ->filterWithKey((function(Tk, Tv): bool) $callback): KeyedIterable<Tk, Tv>
  Returns a KeyedIterable containing the values of the current KeyedIterable that meet a supplied condition applied to its keys and values
• ->firstKey(): ?Tk
  Returns the first key in the current KeyedIterable
• ->firstValue(): ?Tv
  Returns the first value in the current KeyedIterable
• ->getIterator(): KeyedIterator<Tk, Tv>
  Returns an iterator that points to beginning of the current KeyedIterable
• ->keys(): Iterable<Tk>
  Returns an Iterable containing the current KeyedIterable's keys
• ->lastKey(): ?Tk
  Returns the last key in the current KeyedIterable
• ->lastValue(): ?Tv
  Returns the last value in the current KeyedIterable
• ->lazy(): KeyedIterable<Tk, Tv>
  Returns a lazy, access elements only when needed view of the current KeyedIterable
• ->map<Tu>((function(Tv): Tu) $fn): KeyedIterable<Tk, Tu>
  Returns a KeyedIterable containing the values after an operation has been applied to each value in the current KeyedIterable
• ->mapWithKey<Tu>((function(Tk, Tv): Tu) $callback): KeyedIterable<Tk, Tu>
  Returns a KeyedIterable containing the values after an operation has been applied to each key and value in the current KeyedIterable
• ->skip(int $n): KeyedIterable<Tk, Tv>
  Returns a KeyedIterable containing the values after the n-th element of the current KeyedIterable
• ->skipWhile((function(Tv): bool) $fn): KeyedIterable<Tk, Tv>
  Returns a KeyedIterable containing the values of the current KeyedIterable starting after and including the first value that produces true when passed to the specified callback
• ->slice(int $start, int $len): KeyedIterable<Tk, Tv>
  Returns a subset of the current KeyedIterable starting from a given key up to, but not including, the element at the provided length from the starting key
• ->take(int $n): KeyedIterable<Tk, Tv>
  Returns a KeyedIterable containing the first n values of the current KeyedIterable
• ->takeWhile((function(Tv): bool) $fn): KeyedIterable<Tk, Tv>
  Returns a KeyedIterable containing the values of the current KeyedIterable up to but not including the first value that produces false when passed to the specified callback
• ->toImmMap(): ImmMap<Tk, Tv>
  Returns an immutable map (ImmMap) based on the keys and values of the current KeyedIterable
• ->toKeysArray(): varray
  Returns an array with the keys from the current KeyedIterable
• ->values(): Iterable<Tv>
  Returns an Iterable containing the current KeyedIterable's values
• ->zip<Tu>(Traversable<Tu> $traversable): KeyedIterable<Tk, Pair<Tv, Tu>>
  Returns a KeyedIterable where each element is a Pair that combines the element of the current KeyedIterable and the provided Traversable

Public Methods (HH\Iterable)

• ->toImmSet(): ImmSet<Tv>
  Returns an immutable set (ImmSet) converted from the current Iterable
• ->toImmVector(): ImmVector<Tv>
  Returns an immutable vector (ImmVector) converted from the current Iterable
• ->toValuesArray(): varray<Tv>
  Returns an array with the values from the current Iterable