DocumentationHSLReferenceFunctionHH\Lib\C\findx

HH\Lib\C\findx

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This is available as C\findx in the www repository.

Returns the first value of the given Traversable for which the predicate returns true, or throws if no such value is found

namespace HH\Lib\C;

function findx<T>(
  Traversable<T> $traversable,
  (function(T): bool) $value_predicate,
): T;

Time complexity: O(n) Space complexity: O(1)

Parameters

Traversable<T>$traversable
(function(T): bool) $value_predicate

Returns

Examples

$strings = vec["a", "b", "c", "d"];
$predicate_result_1 = C\findx($strings, $x ==> $x == "a");
echo "First predicate: $predicate_result_1\n";
//Output: First predicate: a

$predicate_result_2 = C\findx($strings, $x ==> $x == "z");
//Output: Hit a php exception : exception 'InvariantViolationException' 
//with message 'HH\Lib\C\findx: Couldn't find target value.'