/hphp/hack/test/typecheck/recursive_optional.php

http://github.com/facebook/hiphop-php · PHP · 20 lines · 14 code · 4 blank · 2 comment · 2 complexity · 3a5e68c964596f3327c79ba8e582668d MD5 · raw file 

    

  1. <?hh // partial
    2. 

  2. 

  3. /* HH_FIXME[4336] */
    4. 

  4. function my_compact<T>(Vector<?T> $vector): Vector<T> {
    5. 

  5. }
    6. 

  6. 

  7. function test(bool $b): ?string {
    8. 

  8. 

  9.   $nullable = Vector { null }; // Vector([?T]])
    10. 

  10.   $non_nullable = my_compact($nullable); // Vector([T])
    11. 

  11. 

  12.   if ($b) {
    13. 

  13.     $res = $nullable;
    14. 

  14.   } else {
    15. 

  15.     $res = $non_nullable;
    16. 

  16.   }
    17. 

  17.   // integrating if branches unifies ?T with T, resulting in recursive type
    18. 

  18.   hh_show($res[0]); // Toption(Toption(Toption(Toption(Toption(...)))))
    19. 

  19.   return $res[0];
    20. 

  20. }
    21.