First-class callable syntax in an array_map that reads better

The syntax has been available since 8.1 and I had been using it only for named functions, which misses most of what it is for.

// what I had been writing
$ids = array_map(fn (Order $o): int => $o->id(), $orders);
$totals = array_map([$this, 'lineTotal'], $lines);

// what reads better
$ids = array_map(Order::id(...), $orders);
$totals = array_map($this->lineTotal(...), $lines);

// and the one that matters most, because it type-checks
$handler = $this->dispatch(...);   // Closure, statically known

The array callable form is the one worth replacing everywhere: an analyser can resolve $this->lineTotal(...) and cannot do much with a two-element array, so a rename in an IDE follows one and silently breaks the other. The arrow-function form is not wrong, it is just three tokens longer and introduces a parameter name that has to be read.