Lacking Natural Simplicity

I ran across a couple of interesting articles about Smalltalk History, which I'm linking here for posterity: Bits of History, Words of Advice and The Rise and Fall of Commercial Smalltalk.

After I played D&D for a while at the beginning of my RPG career I found out that I was interested in other games. T&T, then DragonQuest, RuneQuest, GURPS, and Elric! and many more since then. Eventually one of the things I figured out was that I was looking for the different flavors that different RPG systems give the games you play with them. D&D has a very specific flavor. Elric! has a very specific but different flavor. Some of that flavor comes from the systems and some of that flavor comes from the setting. But the D&D systems flavor seems to overpower the setting flavor. (You could say that the “implied setting elements” from the D&D core rules have heavily flavor any D&D setting.)

The Dungeon Fantasy RPG is GURPS specialized for powerful characters plundering dungeons, and because of that it adopts some (but not all) of the cliches from D&D (druids, monks, clerics, etc), and puts its own spin on them. But one of the things I liked about GURPS was that it didn't have the same set of cliches as D&D. Oh well.

Despite looking for the different flavors that systems imbue, I still like generic RPGs like GURPS and Savage Worlds and Basic Roleplaying. I like the flavor that those systems give, and I like seeing how that interacts with the flavor of the setting.

The Bat in the Attic blog has a nice overview of Harnmaster.

S. John Ross's article Medieval Demographics Made Easy (which can be found here) has been used by many gamers to add some verisimilitude to their games. There have been some useful criticisms, however. Here are a couple:

• Lyman Stone's Notes on Medieval Population Geography.

• Ravenwing's Medieval Demographics Done RIGHT: Stuff You Can Us... and Medieval Demographics Done RIGHT (Pt II).

This article started as a message I sent to the the pandoc-discuss Google Group. This version has more links and has been slightly reworded.

I work with ReStructuredText documents a lot and often use pandoc to format them, especially to PDF by way of pandoc's ms output format, which uses groff with the -ms macros to produce the PDF output. Using ms output is fast, groff is usually available on the operating systems I use, and if you do have to install groff it is easy to do and much, much smaller than any TeX distributions.

However, it would be a nice to be able to customize the ms output more for specific input, like if you are using technical writing and are pining for something like the various inline roles of DocBook, or wanted poems to be typeset more stylishly that the ms output does.

You should probably be a little familiar with the Pandoc User Manual and have the documentation for Lua Filter's available for reference while reading this article. And having a reading familiarity with groff and its manual and specifically the -ms macros will be useful too. And maybe Lua as well.

Starting with an article from Dave Jarvis that had an example Lua filter for customizing the ConTeXt output and a little help from the pandoc-discuss mailing list I came up with this example Lua Filter that formats program names and poems specially.

This filter wraps spans with a class, such as from interpreted text roles defined in the source ReST (like :program:`pandoc`) in calls to user defined groff strings \*[start<class>] and \*[stop<class>]. (I've specified the string definitions for \*[startprogram] and \*[stopprogram] in the source ReST as a raw block for ms output but they could be in a customized ms pandoc template, too.) These strings can include groff escapes to change the font and the glyph color and then change back to the previous font and glyph color. In this example I made PDF output for the interpreted text role program come out in a constant width font and in red.

It also wraps divs with classes with calls to user defined groff macros .start<class> and .stop<class> (also included in the source ReST in the raw block for ms output).

For divs with the poem class, it converts any contained LineBlock elements into a list of Plain elements containing its contents, avoiding the ms output for the LineBlock starting with .LP, which would cancel the .DS (display start) macro I want to use in the .startpoem macro definition. The .LP would also reset the font family in use to the default, another reason to avoid it. [1]

The filter also converts the empty element that occurs in the line block as a result of a blank line in the line block input into a RawBlock that creates a blank line in the ms output, to show the division into stanzas of the poem.

Interestingly, the first Str elements in the each line in the content of the line block preserved the leading spaces from the input as Unicode NO-BREAK SPACE characters, preserving indentation of lines in the line block. Unfortunately, the width of those spaces alone is not enough create a visually distinct indentation, so this filter changes those Str elements into a RawInline that outputs a groff horizfontal movement whose width is based on the number of leading NO-BREAK SPACE characters, and follow this with a new Str element that has the leading NO-BREAK SPACE characters removed.

Here is the Lua filter, classify-rst-ms.lua:

onig = require ("rex_onig") -- Need a regex package that understands UTF8.
-- text in LineBreak preserves leading spaces as Unicode NO-BREAK SPACE
leading_nobreakspace_rx = onig.new ("^(\u{a0}+)(.*)$", nil, "UTF8")

function Div( element )
  local annotation = element.classes:find_if( matches )
  local numPara = 0
   if annotation then
     annotation = annotation:gsub( "[^%w]*", "" )
     if annotation == "poem" then
        element = pandoc.walk_block (
           element, {
              -- Replace LineBlock element with a list of Plain elements
              -- containing the LineBlock's subelements.
              LineBlock = function (el)
                 local l = {}
                 for _, subel in ipairs (el.content) do
                    if #subel == 0 then
                       -- If subel is an empty table, output a raw empty line
                       table.insert (l, pandoc.RawBlock ("ms", "\n\n"))
                    else
                       -- Check for leading NO-BREAK SPACE charaters
                       local m1, m2 = onig.match (subel[1].text,
                                                  leading_nobreakspace_rx)
                       if m1 then
                          -- Replace the NO-BREAK SPACE characters with a raw
                          -- groff horizontal movement, because the
                          -- NO-BREAK SPACE characters are too narrow.
                          table.insert (subel, 1, pandoc.RawInline ("ms", string.format ("\\h'%dn'", utf8.len (m1))))
                          -- Modify what was used to be the first item to just
                          -- include the trailing characters of the match.
                          subel[2] = pandoc.Str (m2)
                          table.insert (l, pandoc.Plain (subel))
                       else
                          -- Just put the subel in Plain element.
                          table.insert (l, (pandoc.Plain (subel)))
                       end
                    end
                 end
                 return l
        end })
     end
     return {
        ms( ".start", annotation ),
        element,
        ms( ".stop", annotation )
     }
  end
end

function Span(element)
  local annotation = element.classes:find_if(matches)

  if annotation then
     annotation = annotation:gsub("[^%w]*", "")

     return {
        ms_inline("\\*[start", annotation, "]"),
        element,
        ms_inline("\\*[stop", annotation, "]")
     }
  end
end

function matches( s )
 return s:match( "^%a+" )
end

function ms( macro, annotation )
 return pandoc.RawBlock( "ms", macro .. annotation )
end

function ms_inline (macro, annotation, stop)
  return pandoc.RawInline ("ms", macro .. annotation .. stop)
end

Here is the ReST source of the document, poem-plus.rst:

Lua Filters For Massaging ``ms`` Output
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

.. raw:: ms

   .ds startprogram \\f[CW]\\m[red]
   .ds stopprogram \\m[]\\fP
   .de startpoem
   .ds OLDFAM \\*[FAM]
   .ds FAM BM
   .DS I 3
   ..
   .de stoppoem
   .DE
   .ds FAM \\*[OLDFAM]
   ..

.. role:: program

This is a sentence.  This sentence talks about :program:`pandoc`.
This is
another sentence.

.. class:: poem

   | Some say the world will end in fire,
   |    Some say in ice.
   | From what I've tasted of desire
   |    I hold with those who favor fire.
   | But if it had to perish twice,
   |    I think I know enough of hate
   |    To say that for destruction ice
   |    Is also great,
   | And would suffice.
   |
   | And another line,
   |    And an indented line.

This is a final sentence.

And here is the ms output:

.SH 1
Lua Filters For Massaging \f[CB]ms\f[B] Output
.pdfhref O 1 "Lua Filters For Massaging ms Output"
.pdfhref M "lua-filters-for-massaging-ms-output"
.ds startprogram \\f[CW]\\m[red]
.ds stopprogram \\m[]\\fP
.de startpoem
.ds OLDFAM \\*[FAM]
.ds FAM BM
.DS I 3
..
.de stoppoem
.DE
.ds FAM \\*[OLDFAM]
..
.LP
This is a sentence.
This sentence talks about \*[startprogram]pandoc\*[stopprogram].
This is
another sentence.
.startpoem
Some say the world will end in fire,
\h'3n'Some say in ice.
From what I\[aq]ve tasted of desire
\h'3n'I hold with those who favor fire.
But if it had to perish twice,
\h'3n'I think I know enough of hate
\h'3n'To say that for destruction ice
\h'3n'Is also great,
And would suffice.

And another line,
\h'3n'And an indented line.
.stoppoem
.LP
This is a final sentence.

The command to produce the ms output is:

pandoc -f rst -t ms --lua-filter classify-rst-ms.lua --wrap=preserve poem-plus.rst --output=poem-plus-rst.ms

and the command to produce a PDF is:

pandoc -f rst -t ms --lua-filter classify-rst-ms.lua --wrap=preserve poem-plus.rst --output=poem-plus-rst.ms.pdf

Here is the output PDF.

Being able to rewrite the tree and insert RawBlocks and RawInlines is really powerful when it comes to customizing output for particular output formats.

I hope this example is useful for others like me just learning to use Lua filters.

SBCL and CCL and CLISP think binding a symbol defined with defconstant is an error, so if you do

(defconstant foo "foo")
(let ((foo "bar")) foo)

you get an error. But in ABCL and ECL you don’t.

If you try

(defun x () (let ((foo "bar")) foo))

in SBCL and CCL you get an error when the function is compiled. In SBCL the function is defined, but always gives an error when run. In CCL the function does not get defined.

• Cthulhu: The Mythos and Kindred Horrors, by Robert E. Howard, copyright 1987 by Ala Key Kuykendall and Alla Ray Morris; Baen Publishing Enterprises; ISBN 0-671-65641-4.

I enjoyed reading these again; it has been many years since I have read them. The racism of the stories set in America is what you'd expect from a person of Howard's era, but understanding that, the other elements of the stories make the book worth reading.

• By the Light of the Green Star, by Lin Carter, copyright 1974; DAW Books Number 110.

• As the Green Star Rises, by Lin Carter, copyright 1975; DAW Books; ISBN 0-87997-811-2.

• In the Green Star's Glow, by Lin Carter, copyright 1976; DAW Books.

It is interesting to note that these were popular enough at the time to go into multiple printings, judging from my copies, all of which are later printings except for the second book, When the Green Star Calls. The Amazon reviews of the books in the series are positive as well.

They are definitely fast, fun, pulpy adventures.

I've continued reading Lin Carter's Green Star Sword & Planet novels.

• When the Green Star Calls, by Lin Carter, copyright 1973; DAW Books Number 62.

• By the Light of the Green Star, by Lin Carter, copyright 1974; DAW Books Number 110.

Both of these are short novels, 176 pages for the first and 175 pages for the second. Both end on cliffhangers. In the first the protagonist and his friends are split into two groups, and they are apart the whole in the second.

I've also continued my Sword & Sorcery reading with Norvell W. Page, who is new to me.

• Flame Winds, by Norvell W. Page; copyright 1939 by Street and Smith, Inc., copyright 1967 by Conde Nast Publications, Inc.; Berkley Publishing Corp., 1978.

Well, it was no Conan, but it was entertaining!

I've been looking at Cepheus Engine and I've noticed that there is nothing like the “Typical Activities” checklist that first appeared in The Traveller Book, but which I first encountered in play recently with Starter Traveller. It made a definite impression on me — with this one could improvise a trading session from start to end. I'm not sure yet whether Cepheus Engine supports the completely improvised Traveller adventure talked about on the Tales to Astound blog, but using this with Cepheus Engine would certainly make it easier.