haphpiness

Arrow Functions

PHP 7.4 introduced short closures with the fn keyword. They automatically capture variables from the parent scope (no use() needed), have implicit returns, and are perfect for callbacks.

// Before: verbose closure with explicit `use`
$doubled = array_map(function ($n) {
    return $n * 2;
}, $numbers);

// After: clean, concise, readable
$doubled = array_map(fn($n) => $n * 2, $numbers);

// Parent scope is captured automatically
$tax = 0.21;
$withTax = array_map(fn($price) => $price * (1 + $tax), $prices);

// Great for sorting
usort($users, fn($a, $b) => $a->name <=> $b->name);

// Chain beautifully
$result = array_filter(
    array_map(fn($u) => $u->getProfile(), $users),
    fn($p) => $p->isActive(),
);

Arrow functions don't replace regular closures — they complement them. Use fn for simple transforms and predicates, full closures for multi-line logic. The language gives you both tools and lets you choose.