This is entirely dependent on type detection - as far as I can find there is no way to force a type and for instance when you have a very long integer as a value - in my case 1313035348823 it gets limited to 2147483647 - PHP's max integer.
(PECL yaml >= 0.4.0)
yaml_parse_file — Parse a YAML stream from a file
$pos= 0 [, int
Convert all or part of a YAML document stream read from a file to a PHP variable.
Path to the file.
Document to extract from stream (-1 for all documents, 0 for first document, ...).
ndocs is provided, then it is filled with the
number of documents found in stream.
Returns the value encoded in
input in appropriate
PHP type o
FALSE in caso di fallimento. If
pos is -1 an
array will be returned with one entry for each document found
in the stream.