An experimental fusion of ConTeXt and Lua

This is an experimental syntax sugar for ConTeXt built upon the Lua interface of ConText. It aims at further facilitates those who speak lua to avoid re-learning basic programming concepts, such as assignment, linear structure, control flow, etc., disguised under the exotic syntaxes and definitions of *TeX. It could also avoid certain pitfalls due to the ad-hoc parsers of *TeX.

Nevertheless, the syntax convensions of ConTeXt are preserved as much as possible.

Syntax

The syntax sugar fuses TeX and Lua in a similar way that JSX fuses HTML and Javascript. The Lua syntax is enhanced with one more synax: \{text area}, roughly meaning context.delayed("text area"). Syntax inside the text area includes:

• \% comments
• \(lua code)
• \command(params1)[params2]{text3}(params4)..., equivalent to \(command(params1, {params2}, \{text3}, params4, ...)) or tostring(command) depending on its type
• {..}, creating a lua and TeX scope

The \command is now syntax sugar for lua expressions and is not processed by TeX

Only \, {, } has to be escaped when typeset as string. Ideally the concept of catcode should be transparent to the user as long as we have a decent grammar.

The exact grammar defined with LPeg as well as the desugaring rules are in luax.lua.

Proof of Concept

Save luax.lua and simple_demo.cld into the same directory, run context simple_demo.cld.

The demo is by no means efficient or complete, but should suffice to illustrate the idea.

• setuphead
  • before: \setuphead[myhead][section][numberstyle=bold, textstyle=bold, before=\hairline\blank, after=\nowhitespace\hairline]
  • after: myhead = section:copy{numberstyle='bold', textstyle='bold', before=[[\hairline\blank]], after=[[\nowhitespace\hairline]]}
• setupxtable
  • before: \setupxtable[split=yes, header=repeat, offset=4pt]
  • after: \xtable.setup[split='yes', header='repeat', offset='4pt']
• startxtable

  • before: (see ConTeXt an excursion, section 13.3: Extreme tables)

    \setupxtable[split=yes,header=repeat,offset=4pt]
    \startxtable
     \startxtablehead[align=middle,foregroundstyle=bold]
      \startxrow
       \startxcell[nx=6]  Decline of wealth in Dutch florine (Dfl)  \stopxcell
      \stopxrow
      \startxrow[foregroundstyle=bold]
       \startxcell[width=1.2cm] Year \stopxcell
       \startxcell 1.000--2.000  \stopxcell
       \startxcell 2.000--3.000  \stopxcell
       \startxcell 3.000--5.000  \stopxcell
       \startxcell 5.000--10.000 \stopxcell
       \startxcell   over 10.000 \stopxcell
    
       % .... 50+ more lines

  • after:

    { \(local header = {
          foregroundstyle='bold',
          {width='1.2cm', 'Year'}, '1.000--2.000', '2.000--3.000', '3.000-5.000', '5.000-10.000', 'over 10.000'
        }
        local title = "Decline of wealth in Dutch florine (Dfl)"
      )
      \luax.xtable[split='yes', header='repeat', offset='4pt'][
        head={
             align='middle', foregroundstyle='bold',
             {{nx=6, title}},
             header,
        },
        next={
             {{nx=6, align='middle', foregroundstyle='bold', title.." / Continued"}},
             header,
        },
        body={
             align='middle',
             {1675, 22, '~7', '~5', '~4', '~5'},
             {1724, '~4', '~4', '--', '~4', '~3'},
        },
      ]
    }
    \% `header` and `title` is out of scope and therefore invisible here