[firearm-halter]

The person that creates the config file does not necessarily choose the config file format. In the example, github chose YAML and everyone using github actions must use it. YAML is error prone, as everyone that tests with Python is finding out as the add Python 3.10 to their regression tests. This is a plea to organizations like github to stop choosing YAML.

[rendall]

As not a Python programmer, I'm struggling to understand the issue.

Your (or blogger's) claim is that GitHub misparses the YAML actions config when it comes specifically to Python? Or that YAML is inherently inadequate to the task of representing Python's necessary actions?

[kzrdude]

The Python 3.10 issue is this, in yaml:

  Python_versions:
  - 3.8
  - 3.9

Then we add the new version in our yaml file:

  Python_versions:
  - 3.8
  - 3.9
  - 3.10

But now we discover that 3.10 is parsed as a float, just like the other ones were. But the problem is that 3.10 becomes 3.1, the equivalent float value! With 3.9 we didn't notice this problem.

I'm not sure what the name for this problem is.

It's something like.. an unfaithful but unintentionally working representation. Until it doesn't work anymore. The solution in YAML is to quote the values so that they become strings as intended.

[jeroenhd]

How is that different from other formats? Take JSON:

    {"python_versions": [3.8, 3.9, 3.10]}

This is a problem in any config language that doesn't enforce types, and jf it does enforce types, you should've used quotes already (like you really should've been before 3.10 was added to the list).

Similar problems also exist in many config formats with scientific notation (2e345) or hexadecimal notation (0x12345) or octal notation (012345, no that's not a decimal number in many programming languages and config formats!).

What commonly supported alternative would you suggest for this use case?

[kzrdude]

The difference from JSON is that in JSON, you always have to write "" to get strings.

In YAML you can just write blah and and it becomes a string. Except when it doesn't, when it matches some other type of value.

[sigzero]

Sure, if you ignore what the YAML documentation actually says.

[deadbunny]

> I'm not sure what the name for this problem is.

Not reading the manual? Same thing would happen in JSON.

Sure it's annoying but all the YAML docs I've ever read state that unquoted numbers are ints/floats.

[ccouzens]

YAML is a superset of JSON.

Which means anything that accepts YAML accepts JSON.

So you can write your Github action code in JSON (with a yml file extension).

[bmn__]

> YAML is a superset of JSON.

That's false. http://p3rl.org/JSON::XS#JSON-and-YAML

[ccouzens]

Interesting. Thanks for bringing that to my attention.

It sounds like the differences are unlikely to be encountered in conventional config files, especially those written by hand.

From that link I understand the source of problems to be:

Object keys longer than 1024 "stream characters". But these wouldn't be valid in any other yaml syntax either.

Some Unicode characters in strings (characters outside of BMP).

An escape sequence that is technically valid in JSON but never required.