Hack
HHVM
报告 bug 或提出建议。
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Hack
Reference
Interface
HH\Iterable
firstValue
HH\Iterable::firstValue
Returns the first value in the current
Iterable
public function firstValue(): ?Tv;
Returns
?Tv
- The first value in the current
Iterable
, or
null
if the current
Iterable
is empty.