$x . ' world', fn (string $z): string => $z . '!!' ); self::assertSame('Hello world!!', $x('Hello')); } public function testItCombinesAFunctionThatDealWithDifferentTypes(): void { $x = Fun\after( fn (string $x): int => Str\length($x), fn (int $z): string => $z . '!' ); self::assertSame('5!', $x('Hello')); } }