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slice

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.

Returns a subset of the current ImmSet starting from a given key up to, but not including, the element at the provided length from the starting key

public function slice(
  int $start,
  int $len,
): ImmSet<Tv>;

$start is 0-based. $len is 1-based. So slice(0,2) would return the elements at key 0 and 1.

The returned ImmSet will always be a proper subset of the current ImmSet.

Parameters​

  • int $start - The starting value in the current ImmSet for the returned ImmSet.
  • int $len - The length of the returned ImmSet.

Returns​

  • ImmSet<Tv> - An ImmSet that is a proper subset of the current ImmSet starting at $start up to but not including the element $start + $len.

Examples​

See Set::slice for usage examples.