@ 2019-02-12T22:35:01Z

<?php declare(strict_types=1); $f = function (string $x): string { return $x; }; try { $f(1); } catch (\TypeError $e) { echo 'Good, $f does not take ints' . PHP_EOL; } \assert(array_map($f, [1, 2, 3]) !== [1, 2, 3]); \assert(array_map($f, [1, 2, 3]) === ['1', '2', '3']); echo 'Huh ???' . PHP_EOL; $p = function (string $_): bool { return false; }; try { $p(1); } catch (\TypeError $e) { echo 'Good, $p does not take ints' . PHP_EOL; } \assert(array_filter([1, 2, 3], $p) === []); echo 'Huh ???' . PHP_EOL; /* http://php.net/manual/en/functions.arguments.php#functions.arguments.type-declaration.strict Strict typing applies to function calls made from within the file with strict typing enabled, not to the functions declared within that file. If a file without strict typing enabled makes a call to a function that was defined in a file with strict typing, the caller's preference (weak typing) will be respected, and the value will be coerced. */