fish shell is looking for a new text serialization format for its history file (currently it uses an ad-hoc broken psuedo-YAML).

Boxes to check:

1. Self describing format

2. SAX-style parser available to C++

3. Easy for users to understand and ad-hoc parse using command-line tools

4. No document closing necessary, so appending is trivial

YAML looks pretty good:

    - cmd: git checkout file.txt
      when: 1565133286
      pwd: /home/me/dir/
      paths:
      - file.txt

protobuf is also an option:

    entry {
      cmd: "git checkout file.txt"
      when: 1565133286
      paths: "file.txt"
    }

though I am unsure of how well its text serialization is supported.

Any suggestions?