hphp/hack/test/typecheck/generic_fun_3.php

   1 <?hh // strict
   2 // Copyright 2004-present Facebook. All Rights Reserved.
   3
   4 function darray_filter<Tk as arraykey, Tv>(
   5   KeyedTraversable<Tk, Tv> $traversable,
   6   ?(function(Tv): bool) $f,
   7 ): darray<Tk, Tv> {
   8   return darray[];
   9 }
  10
  11 function is_not_null<T>(T $x): bool {
  12   return false;
  13 }
  14 class C {}
  15 class D {}
  16 function testit(varray<?C> $vc, varray<?D> $vd): void {
  17   $func = fun('is_not_null');
  18   $a = darray_filter($vd, $func);
  19   $b = darray_filter($vc, $func);
  20 }