Debugging functionality

[lf-]

Hi!

I have some hpack includes which aren't working due to, erm, probably, what we refer to as "yaml footguns" at work:

# /!\ /!\ /!\ /!\ /!\ /!\ /!\
# /!\ YAML FOOTGUN ALERT  /!\
# /!\ /!\ /!\ /!\ /!\ /!\ /!\
#
# Be warned, future traveler: YAML documents can only have one value for each
# key. So if we define a key in this document:
#
#     when:
#     - condition: ...
#       ghc-options: ...
#
# And then in `../package.yaml` we do
#
#     <<: !include hpack-common/defaults.yaml
#     when:
#     - condition: ...
#       ghc-options: ...
#
# Then the flags defined here will be completely and unceremoniously erased!
# Therefore, we define _anchors_ for these values which we can reuse in
# `../package.yaml` (where we want to add additional mwb-specific flags)
# _and_ a default value for `when:` that will be used in (e.g.)
# `../local-packages`.
#
# See: https://stackoverflow.com/a/46644785

The include system adds enough complexity that I would really really like to be able to dump out the resulting YAML that is being evaluated, so that I can figure out where each value like when is coming from. As far as I can tell from the highly limited output of --help, there is no way to dump this:

Usage: hpack [ --silent ] [ --canonical ] [ --force | -f ] [ --[no-]hash ] [ PATH ] [ - ]
       hpack --version
       hpack --numeric-version
       hpack --help

[sol]

You are right, there is not. What I would recommend to do is

• extend yaml2json (part of the yaml package) so that it interprets include statements
• use yaml2json for debugging

Note that yaml2json is frequently useful to debug other YAML related issues, extending it with support for includes will make it even more useful.

If you happen to open a PR for yaml2json, please feel free to ping me, and I will try to take a look at your code.