php - How to dump an empty array using Symfony Yaml -

i'm trying use symfony yaml dump function output nested php array data.

use \symfony\component\yaml\yaml;  echo yaml::dump([     'arr'=>[],     'foo'=>'bar', ]); 

however, dumped yaml contains empty object:

arr: {  } foo: bar 

while want empty list:

arr: [] foo: bar 

i tried using yaml::dump_object_as_map flag, using arrayobject instead of array literals, , using emptyiterator, no avail.

i found 2 closed bugs related this: https://github.com/symfony/symfony/issues/9870 , https://github.com/symfony/symfony/issues/15781, solutions there don't seem work, or bit hacky , brittle taste (str_replace on yaml output, brrrr)

i have simple testcase tried far: https://github.com/comavn/php-yaml-empty-array

any suggestions on how fix this?

as of symfony 3.3 (released may 2017) can use new yaml::dump_empty_array_as_sequence option:

yaml::dump($object, 2, 4, yaml::dump_empty_array_as_sequence); 

this feature added in pr 21471.