YAML sucks.

YAML source	yaml2json.hs	yaml2json.py	yaml2json.pl
<<	"\u003c\u003c"	could not determine a constructor for the tag 'tag:yaml.org,2002:merge' in "", line 1, column 1	YAML Error: Expected separator '---' Code: YAML_PARSE_ERR_NO_SEPARATOR Line: 1 Document: 2 at /usr/share/perl5/YAML/Loader.pm line 81.
"<<"	"\u003c\u003c"	"<<"	YAML Error: Expected separator '---' Code: YAML_PARSE_ERR_NO_SEPARATOR Line: 1 Document: 2 at /usr/share/perl5/YAML/Loader.pm line 81.
<<: {}	{}	{}	{"<<":{}}
"<<": {}	{}	{"<<": {}}	{"<<":{}}
<<: a	{"\u003c\u003c":"a"}	while constructing a mapping in "", line 1, column 1 expected a mapping or list of mappings for merging, but found scalar in "", line 1, column 5	{"<<":"a"}
- undefined - null - false - true - n - y - off - on	["undefined",null,false,true,false,true,false,true]	["undefined", null, false, true, "n", "y", false, true]	["undefined"]
- 8 - 08	[8,8]	[8, "08"]	["8"]