Returns the value at the specified key in the current Pair

public function at(
  int $key,
): mixed;

If the key is not present, an exception is thrown. This essentially means if you specify a key other than 0 or 1, you will get an exception. If you don't want an exception to be thrown, use get() instead.

$v = $p->at($k)" is semantically equivalent to $v = $p[$k].


  • int $key - the key from which to retrieve the value.


  • mixed - The value at the specified key; or an exception if the key does not exist.


This example prints the first and second values of the Pair:

$p = Pair {'foo', -1.5};

// Print the first element

// Print the second element

This example throws an OutOfBoundsException because a Pair only has the indexes 0 and 1:

$p = Pair {'foo', -1.5};

// Index 2 doesn't exist because pairs always have exactly two elements