[WIP]: Lua: Add function pandoc.init

[tarleb]

This function allows to initialize the state in PANDOC_STATE, but only if it hasn't been initialized yet. The function has no effect in filters and custom readers/writers, but only in standalone scripts.

Any function that queries the state will cause it to be auto-initialized to the default value, so there should be no behavior changes.

The Haskell API probably needs more work, I tried to keep changes small for now.

[jgm]

Could you say a bit more about the kind of things that would require this, by way of motivation?

[tarleb]

Sure, sorry. The background is that I'm extending the Inara system used by JOSS, because I need to create files with names that are built from metadata values to match the schema expected by PUBMED. I don't want to use much shell scripting for that, which is why I'm trying to write it as a standalone Lua script. [WIP]

There script always runs with the default CommonState, so without user data directory and . as resource path. It's not a big problem, because it's fairly easy to work around this, but some code would be shorter if I could configure the CommonState. The goal would be to write something like

pandoc.init {
  user_data_dir = '/usr/share/openjournals/data',
}

so I could do things like

local template = pandoc.template.default 'html5'

to get templates from that data directory (if they exist).

In summary, it's less that I need it, and more that it seems to be a missing functionality that potentially helpful in some cases.

[jgm]

No objections on my part!