Lua filters: allow using SimpleTable instead of Table

[tarleb]

Old filters using tables now require minimal changes and can use

if PANDOC_VERSION > {2,10,1} then
  pandoc.Table = function(c,a,w,h,r)
    return pandoc.utils.from_simple_table(pandoc.SimpleTable(c,a,w,h,r))
  end
end

and

function Table (tbl)
  smpl_tbl = pandoc.utils.to_simple_table(tbl)
  return pandoc.utils.from_simple_table(smpl_tbl)
end

to work with the current pandoc version.

[tarleb]

A new block type SimpleTable would be introduced, effectively behaving like old Table blocks (except for the tag).

This is a draft, as I couldn't fully convince myself that this is the best way forward. It requires some unfortunate special-casing, but otherwise seems to work quite well.

[jgm]

A simpler approach might be not to add SimpleTable as a faux block element, but instead add a function that treats the element as a simple table. That is:

function Table(el)
  local el2 = to_simple_table(el)
  -- do stuff with el2
  return from_simple_table(el)
end

or maybe this could be encapsulated in one function

   with_simple_table(el, function(el2) ... end)

[tarleb]

If I understand correctly, then this would make SimpleTable a standalone type which does not inherit from type Block. We'd be moving the unmarshaling code for SimpleTable into a separate function, which is then exposed to Lua. That does seem cleaner.

[jgm]

I'm sorry, I sort of lost track of this. Do you want to rebase so we can see if the tests pass?

[tarleb]

Rebased, squashed, and updated the commit message.

[tarleb]

Cabal-based tests fail because

1. there's a problem with text-conversions, which require us to add constraints: base16-bytestring < 1 to cabal.project and
2. pandoc-citeproc hasn't been updated yet to allow pandoc-types-1.22.

Stack-based tests succeed.

[jgm]

What's the problem with text-conversions?
And where do we depend on that library?

[jgm]

I've pushed a commit that uses the dev version of pandoc-citeproc.

[tarleb]

Thanks!

What's the problem with text-conversions?

IIUC, then there has been a new release of base16-bytestring which breaks text-conversions, as that package does not set an upper bound for base16-bytestring. Relevant discussion.

And where do we depend on that library?

It is a dependency of doctemplates. It seems that we also use it in function addVariablesToContext in module Text.Pandoc.Writers.Shared.