kill9/harmful/software/yaml.md

YAML makes no sense

There's a lot of ways to say true or false in YAML (21 I think). Some of them are very inconvinient. For example

countries:
    - ES
    - DE
    - FR
    - GB
    - US
    - NO <- This isn't Norway, This is false

If you use YAML instead of literally anything else, is because you hate the quotes in this kind of stuff. But you literally have to do this:

countries:
    - ES
    - DE
    - FR
    - GB
    - US
    - "NO" <- Alright, not false anymore.

YAML can understand both tabs and spaces as indentation methods. It depends on the implementation if they are supported and many don't support it. So you're usually stuck working with spaces in YAML files instead of tabs.

editors:
    - vi
    - emacs
    - ed

functions:
  - read <- Here's where the parsers will get confused
  - write

If you thought indentation is a problem, you will have a bigger problem with complex structures. Here's array colors that contains two elements.

colors:
    -
      red: valid
      hex: "FF000000"
    - cow:
      hex: none

This roughly translates to:

colors = { 
	{ red: "valid", hex: "FF000000"},
	cow = { hex: "none" }
}

YAML also decided to be special and add includes. How they work depends on the implementation. Here's a good example on how to abuse it:

users:
    - name: Chris
      repositories: &chrisrepos
          - emacsconf
	  - dotfiles
    - name: Marie
      repositories: *chrisrepos
	  - emacsconf-improved
    - name: John
      repositories: *chrisrepos

One would guess that John has access to Chris' repositories and Marie too with the added -improved repository but this is invalid. You need to use <<: *chrisrepos on the next line to append/override values. Wasted reserved keynames for things that already exist.

YAML doesn't require you to quote your strings which should result in simpler writing for humans. But here's some weird cases where this results in parsing problems. Try to guess how many of these are strings and how many are integers.

value1: 42423
value2: +0x_324_bad
value3: -9_90_99_0:39:1
value4: -0_
value5: 0_0_0_0_0

If you guessed all, you are right. YAML allows all kinds of things in integers to make it more readable to humans and to make implementations more complicated.