2019-08-14 11:34:00

16 files changed, 813 insertions, 0 deletions

diff --git a/doc/context/documents/general/magazines/mag-1104-mkiv.pdf b/doc/context/documents/general/magazines/mag-1104-mkiv.pdf
new file mode 100644
index 000000000..ee73daea5
--- /dev/null
+++ b/doc/context/documents/general/magazines/mag-1104-mkiv.pdf
diff --git a/doc/context/documents/general/qrcs/setup-cs.pdf b/doc/context/documents/general/qrcs/setup-cs.pdf
index 053434a00..eec546a8f 100644
--- a/doc/context/documents/general/qrcs/setup-cs.pdf
+++ b/doc/context/documents/general/qrcs/setup-cs.pdf
diff --git a/doc/context/documents/general/qrcs/setup-de.pdf b/doc/context/documents/general/qrcs/setup-de.pdf
index d2c3e3970..206ed45b1 100644
--- a/doc/context/documents/general/qrcs/setup-de.pdf
+++ b/doc/context/documents/general/qrcs/setup-de.pdf
diff --git a/doc/context/documents/general/qrcs/setup-en.pdf b/doc/context/documents/general/qrcs/setup-en.pdf
index 0060c1245..9c6b51114 100644
--- a/doc/context/documents/general/qrcs/setup-en.pdf
+++ b/doc/context/documents/general/qrcs/setup-en.pdf
diff --git a/doc/context/documents/general/qrcs/setup-fr.pdf b/doc/context/documents/general/qrcs/setup-fr.pdf
index ad12d606f..1e3bb51fd 100644
--- a/doc/context/documents/general/qrcs/setup-fr.pdf
+++ b/doc/context/documents/general/qrcs/setup-fr.pdf
diff --git a/doc/context/documents/general/qrcs/setup-it.pdf b/doc/context/documents/general/qrcs/setup-it.pdf
index ba2082c5e..d62f091e5 100644
--- a/doc/context/documents/general/qrcs/setup-it.pdf
+++ b/doc/context/documents/general/qrcs/setup-it.pdf
diff --git a/doc/context/documents/general/qrcs/setup-mapping-cs.pdf b/doc/context/documents/general/qrcs/setup-mapping-cs.pdf
index 8fe71aaa5..2695239de 100644
--- a/doc/context/documents/general/qrcs/setup-mapping-cs.pdf
+++ b/doc/context/documents/general/qrcs/setup-mapping-cs.pdf
diff --git a/doc/context/documents/general/qrcs/setup-mapping-de.pdf b/doc/context/documents/general/qrcs/setup-mapping-de.pdf
index b17b2ac41..c57684098 100644
--- a/doc/context/documents/general/qrcs/setup-mapping-de.pdf
+++ b/doc/context/documents/general/qrcs/setup-mapping-de.pdf
diff --git a/doc/context/documents/general/qrcs/setup-mapping-en.pdf b/doc/context/documents/general/qrcs/setup-mapping-en.pdf
index c6d67a543..b63d13dac 100644
--- a/doc/context/documents/general/qrcs/setup-mapping-en.pdf
+++ b/doc/context/documents/general/qrcs/setup-mapping-en.pdf
diff --git a/doc/context/documents/general/qrcs/setup-mapping-fr.pdf b/doc/context/documents/general/qrcs/setup-mapping-fr.pdf
index cc32921ec..16fe62c4e 100644
--- a/doc/context/documents/general/qrcs/setup-mapping-fr.pdf
+++ b/doc/context/documents/general/qrcs/setup-mapping-fr.pdf
diff --git a/doc/context/documents/general/qrcs/setup-mapping-it.pdf b/doc/context/documents/general/qrcs/setup-mapping-it.pdf
index d381bab3f..79feb3bb0 100644
--- a/doc/context/documents/general/qrcs/setup-mapping-it.pdf
+++ b/doc/context/documents/general/qrcs/setup-mapping-it.pdf
diff --git a/doc/context/documents/general/qrcs/setup-mapping-nl.pdf b/doc/context/documents/general/qrcs/setup-mapping-nl.pdf
index 7c756960b..81e6b0e8f 100644
--- a/doc/context/documents/general/qrcs/setup-mapping-nl.pdf
+++ b/doc/context/documents/general/qrcs/setup-mapping-nl.pdf
diff --git a/doc/context/documents/general/qrcs/setup-mapping-ro.pdf b/doc/context/documents/general/qrcs/setup-mapping-ro.pdf
index b31992fa1..e5560e2cf 100644
--- a/doc/context/documents/general/qrcs/setup-mapping-ro.pdf
+++ b/doc/context/documents/general/qrcs/setup-mapping-ro.pdf
diff --git a/doc/context/documents/general/qrcs/setup-nl.pdf b/doc/context/documents/general/qrcs/setup-nl.pdf
index 2132fc97d..0a6d65781 100644
--- a/doc/context/documents/general/qrcs/setup-nl.pdf
+++ b/doc/context/documents/general/qrcs/setup-nl.pdf
diff --git a/doc/context/documents/general/qrcs/setup-ro.pdf b/doc/context/documents/general/qrcs/setup-ro.pdf
index 5877b9de7..c3d5de9c8 100644
--- a/doc/context/documents/general/qrcs/setup-ro.pdf
+++ b/doc/context/documents/general/qrcs/setup-ro.pdf
diff --git a/doc/context/sources/general/magazines/mag-1104-mkiv.tex b/doc/context/sources/general/magazines/mag-1104-mkiv.tex
new file mode 100644
index 000000000..4cbc3d921
--- /dev/null
+++ b/doc/context/sources/general/magazines/mag-1104-mkiv.tex
@@ -0,0 +1,813 @@
+% author    : Hans Hagen
+% copyright : PRAGMA ADE & ConTeXt Development Team
+% license   : Creative Commons Attribution ShareAlike 4.0 International
+% reference : pragma-ade.nl | contextgarden.net | texlive (related) distributions
+% origin    : the ConTeXt distribution
+%
+% comment   : Because this manual is distributed with TeX distributions it comes with a rather
+%             liberal license. We try to adapt these documents to upgrades in the (sub)systems
+%             that they describe. Using parts of the content otherwise can therefore conflict
+%             with existing functionality and we cannot be held responsible for that. Many of
+%             the manuals contain characteristic graphics and personal notes or examples that
+%             make no sense when used out-of-context.
+
+\usemodule[magazine-basic,abr-02]
+
+\usemodule[scite]
+
+\startbuffer[abstract]
+    As part of the \CONTEXT\ \LMTX\ project, we experiment with new ways to
+    interface subsystems and \METAPOST\ makes a good candidate. Here I wrap up some
+    experiments. It's not a manual or a recipe, just food for thought. All you see
+    here might change and|/|or evolve.
+\stopbuffer
+
+\setuplayout
+  [backspace=20mm,
+   topspace=10mm]
+
+\startdocument
+  [title={New interfacing in \METAFUN, a preview},
+   author={Hans Hagen & Alan Braslau},
+  %affiliation=PRAGMA ADE,
+   date=July 2019,
+   number=1104 LMTX]
+
+As we move to \CONTEXT\ \LMTX, some decisions need to be made. For instance, how
+shall we introduce new functionality while not affecting the \MKIV\ code base too
+much with engine related tests, messy and performance sapping. Of course we
+remain downward compatible but the \LUAMETATEX\ engine sometimes permits multiple
+solutions. As this is something new, for a while we can use experimental features
+that may change or later disappear depending on experience. It is not a big deal
+to adapt to these new possibilites and users shouldn't notice, unless of course
+they currently employ (yet undocumented) low|-|level features. Part of the
+solution is to have separate files for \MKIV\ and \LMTX, although that will
+mostly concern low level support modules; even then differences will be subtle
+and should not affect users. I must admit that some of those changes are mostly
+aesthetic and often don't improve performance, although better performance
+sometimes may be the case, in particular concerning \quote {extreme} usage.
+
+But, that said, there are areas where \LMTX\ will offer entirely new
+functionality. One of the areas where we are making interesting developments is
+in \METAFUN, which means \METAPOST. Now, it is not to be said that some of the
+core functionality needed for this will migrate from \LUAMETATEX\ (used by \LMTX)
+to \LUATEX\ (used by \MKIV). But, because (due to external pressure), the later
+engine is now considered stable and its functionality frozen, it is not likely to
+be quickly backported or at least only will happen when this has been throughly
+tested in \CONTEXT|/|\LMTX.
+
+Over the years there have been (small) improvements in the interface but while
+Alan Braslau and I experiment with new graphic abilities, we also are coming up
+with (graphic) interfaces that suit \CONTEXT\ much better. Below, I will show
+some examples. \footnote {These optional argument handlers themselves are
+\emphasize {not} part of \METAPOST\ but implemented in \CONTEXT\ using some
+experimental parsing related extensions to a version of \MPLIB\ used in
+\LUAMETATEX.}
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_grid [
+        nx =  20, ny =  10,
+        dx =   5, dy =   2,
+        tx =  10, ty =  10,
+    ] ysized 5cm withpen pencircle scaled 1mm withcolor "red" ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+What we see here is an key|/|value driven interface that has been one of the
+unique core properties of \CONTEXT\ since it was created. \footnote {Note the use
+of the color string \type {"red"} rather then the \METAPOST\ color variable \type
+{red := (1,0,0)}. This is a small detail but here imports the color definition
+from \CONTEXT, which might be a bit special.} Of course parameters can be
+optional as demonstrated in:
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_grid [
+        nx =  10, ny =  10,
+        dx =   1, dy =   1
+    ] ysized 3cm
+        withpen pencircle scaled 1mm
+        withcolor "darkblue"  ;
+
+    draw lmt_grid [
+        nx = 10, ny = 10
+    ] ysized 3cm shifted (4cm,0)
+       withpen pencircle scaled .3mm
+       withcolor "darkgreen" ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+This syntax means that we can also use the already used interface documentation
+system.
+
+We can actually go quite far in what we provide. It's not so much that these
+things were not possible before, but the more concise user interface is something
+new indeed. Let's start with drawing some simple axis:
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_axis [
+        nx =  20, ny =  10,
+        dx =   5, dy =   2,
+    ] ysized 4cm
+        withpen pencircle scaled 1mm
+        withcolor "darkcyan" ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+This \quote {article} is not meant as tutorial but more as a teaser about what is
+possible and hopefully it triggers users in coming up with useful demands. As the
+previous axis example is not that interesting we move on to a more complex one:
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_axis [
+        sx =   5mm, sy =   5mm,
+        nx =  20,   ny =  10,
+        dx =   5,   dy =   2,
+        tx =  10,   ty =  10,
+    ] withpen pencircle scaled 1mm withcolor "darkblue" ;
+
+    draw lmt_connected (
+        for i = 1 step 2 until 20 :
+            -- (i, 1 randomized 8) * 5mm
+        endfor
+    )
+        withpen pencircle scaled 2mm withcolor "darkyellow" ;
+
+    draw lmt_connected (
+        for i = 1 step 2 until 20 :
+            lmt_connection (i, 1 randomized 8) * 5mm
+        endfor
+    )
+        withpen pencircle scaled 2mm withcolor "darkgreen" ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+These examples are made as part of exploring how to best interface with
+\METAPOST, to be used by the upcoming luagraph module, a flexible and high
+performance set of macros aimed at drawing graphs and to visualize data. On the
+one hand, we want to free the user from dealing with details such as scales to
+get the graphics right, but on the other hand it should be possible to
+fine|-|tune when needed.
+
+Again we draw an axis. Using strings as color names, mentioned in the footnote
+earlier, is not new, but already present for a while. It will use the colors
+defined at the \TEX\ end and is more convenient and natural than using the older
+\type {\MPcolor}. The \type {lmt_connected} macro is sort of a gimmick: if you
+look closely you will see that it has to start with a point (coordinate) but that
+one is discarded silently. Again this is something we need to deal with.
+
+% This is obscure, and silly. I'm sure that we can do better. Sure, but so is the
+% HIDE related alternative trrickery. We probably need something getparameterpath.
+
+The next variant uses a list of samples. Watch the use of braces, this is
+something normally not part of \METAPOST\ syntax, and it signals a \LUA|-|like
+list. This is a choice of interfacing. There are subtle and somewhat complicated
+aspects involved here as \METAPOST\ parsing involves primaries, secondaries,
+tertiaries and expressions, symbols, strings, tags and other specialities.
+
+% Why does samples = {} require a second pair of brackets? Wouldn't a
+% comma-separated list be enough in Lua? Because it's \METAPOST\ which has its own
+% ideas about where expressions start and end.
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_axis [
+        sx     =  5mm, sy     =  5mm,
+        nx     = 20,   ny     = 10,
+        dx     =  5,   dy     =  2,
+        tx     =  5,   ty     =  2,
+        startx =  1,   starty =  0,
+
+        connect = true,
+        samples = {
+            {
+                4, 2, 4, 9, 3, 0, 8, 9, 10, 1,
+                5, 3, 0, 8, 5, 6, 10, 2, 3, 5
+            }
+        },
+        axiscolor    = "darkgreen",
+        textcolor    = "darkred",
+        samplecolors = {
+            "darkblue"
+        },
+    ] withpen pencircle scaled 1mm ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+We can have multiple sample lists. But of course dealing with that is really up
+to the underlying code, which itself is not that much related to \METAPOST\ but
+has been delegated to \LUA.
+
+\startbuffer
+\definecolor[tdarkred]  [r=.6,a=1,t=.5]
+\definecolor[tdarkgreen][g=.6,a=1,t=.5]
+\definecolor[tdarkblue] [b=.6,a=1,t=.5]
+
+\startMPcode{doublefun}
+    save u ; let u = uniformdeviate ;
+    draw lmt_axis [
+        sx =  5mm, sy =  5mm,
+        nx = 20,   ny = 10,
+        dx =  5,   dy =  2,
+        tx = 10,   ty =  2,
+        samples = {
+            {
+                u10, u10, u10, u10, u10,
+                u10, u10, u10, u10, u10,
+                u10, u10, u10, u10, u10,
+                u10, u10, u10, u10, u10
+            },
+            {
+                u10, u10, u10, u10, u10,
+                u10, u10, u10, u10, u10,
+                u10, u10, u10, u10, u10,
+                u10, u10, u10, u10, u10
+            },
+            {
+                u10, u10, u10, u10, u10,
+                u10, u10, u10, u10, u10,
+                u10, u10, u10, u10, u10,
+                u10, u10, u10, u10, u10
+            }
+        },
+        startx       = 1,
+        starty       = 0,
+        connect      = true,
+        axiscolor    = "darkgray",
+        textcolor    = "darkyellow",
+        samplecolors = {
+            "tdarkred",
+            "tdarkgreen",
+            "tdarkblue"
+        },
+    ] withpen pencircle scaled 1mm ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+Yet another interesting variant might be this:
+
+\startbuffer
+\startluacode
+    documentdata["lmx-sample-1"] = {
+        {
+            4, 2, 4, 9, 3, 0, 8, 9, 10, 1,
+            5, 3, 0, 8, 5, 6, 10, 2, 3, 5
+        }
+    }
+\stopluacode
+\stopbuffer
+
+\typebuffer[option=TEX] \getbuffer
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_axis [
+        sx     = 5mm, sy     = 5mm,
+        nx     = 20,  ny     = 10,
+        dx     = 5,   dy     = 2,
+        tx     = 5,   ty     = 2,
+        startx = 1,   starty = 0,
+
+        samples      = "lmx-sample-1",
+        axiscolor    = "darkgreen",
+        textcolor    = "darkred",
+        samplecolors = { "darkblue" },
+    ] withpen pencircle scaled 1mm ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+% OOPS, doesn't work!
+
+Adding more tricks is not that complex, take, for example:
+
+\startbuffer
+\startMPcode{doublefun}
+draw lmt_axis [
+    sx =  5mm, sy =  5mm,
+    nx = 20,   ny = 10,
+    dx =  5,   dy =  2,
+    tx = 10,   ty = 10,
+
+    list = {
+        [
+            connect = true,
+            color   = "darkred",
+            close   = true,
+            points  = { (1, 1), (15, 8), (2, 10) },
+            texts   = { "segment 1", "segment 2", "segment 3" }
+        ],
+        [
+            connect = true,
+            color   = "darkgreen",
+            points  = { (2, 2), (4, 1), (10, 3), (16, 8), (19, 2) },
+            labels  = { "a", "b", "c", "d", "e" }
+        ],
+        [
+            connect = true,
+            color   = "darkblue",
+            close   = true,
+            points  = { (5, 3), (8, 8), (16, 1) },
+            labels  = { "1", "2", "3" }
+        ]
+    },
+
+] withpen pencircle scaled 1mm  ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+yielding
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+but this is experimentation, work in progress, not to be taken as settled.
+
+\blank
+
+A variant on this one is the following:
+
+\startbuffer
+\startMPcode{doublefun}
+draw lmt_function [
+
+    xmin =  0, xmax = 10, xstep = .05,
+    ymin = -2, ymax =  2,
+
+    xticks = "bottom", xsmall = 80, xlarge = 20,
+    yticks = "left",   ysmall = 40, ylarge =  4,
+
+    code = "1.5 * math.cosd(240 * math.sqrt(x))",
+
+    xlabels = "yes",
+    ylabels = "yes",
+
+    ycaption = "\strut\tfd \rotate[rotation=90]{vertical}",
+    xcaption = "\strut\tfd horizontal",
+
+    pointsymbol = "dot", pointsize = 4, pointcolor = "orange",
+
+    sx = 2mm, sy = 4mm, linewidth = .025mm, offset = .1mm,
+]
+    xsized 8cm
+;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+A valid question is if this should be combined with the previous but having
+distinctive variants is less likely to complicate the settings, as these can
+depend on the application:
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+A more complex usage (still under exploration) is demonstrated next:
+
+\startbuffer
+\definecolor[MyColorR][r=.5,t=.5,a=1]
+\definecolor[MyColorG][g=.5,t=.5,a=1]
+\definecolor[MyColorB][b=.5,t=.5,a=1]
+\definecolor[MyColorY][r=.5,g=.5,t=.5,a=1]
+
+\startMPcode{doublefun}
+draw lmt_function [
+    sx = 1mm, sy = 4mm, linewidth = .025mm, offset = .1mm,
+
+    xmin =  0, xmax = 20, xstep     = .1,
+    ymin = -2, ymax =  2,
+
+    xticks = "bottom", xsmall = 80, xlarge = 20, xlabels = "nolimits",
+    yticks = "left",   ysmall = 40, ylarge =  4, ylabels = "yes",
+
+    code  = "1.5 * math.sind (50 * x - 150)",
+
+    frame = "sticks", % "ticks"
+
+    functions = {
+        [
+            xmin      =  1.0,
+            xmax      =  7.0,
+            close     = true,
+            fillcolor = "MyColorR"
+        ],
+        [
+            xmin      =  7.0,
+            xmax      = 12.0,
+            close     = true,
+            fillcolor = "MyColorG"
+        ],
+        [
+            xmin      = 12.0,
+            xmax      = 19.0,
+            close     = true,
+            fillcolor = "MyColorB"
+        ],
+        [
+            drawcolor = "darkyellow",
+            drawsize  = 2,
+        ],
+        [
+            xmin      =   4,
+            xmax      =  17,
+            xstep     = .25,
+            drawcolor = "darkmagenta",
+            shape     = "steps",
+            code      = "0.5 * math.random(-2,2)",
+        ],
+        [
+            xmin      =  5.0,
+            xmax      = 15.0,
+            close     = true,
+            fillcolor = "MyColorY"
+            code      = "1.75 * math.cosd (50 * x - 150)",
+        ]
+    },
+    ycaption  = "\rotate[rotation=90]{\tfd\strut a mix of drawings}",
+    xcaption  = "\framed[foregroundstyle=\tfd]{a mixture of $\sin(x), \cos(x), \sqrt{x}$ etc.}",
+]
+    xsized 8cm
+;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+Of course calling the same command multiple times with different code snippets
+will also work.
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+The previous examples used new code but how about improving existing features?
+Let's look at outlines.
+
+\startbuffer
+\startMPcode{doublefun}
+    save h ; h = 12mm ;
+
+    draw lmt_outline [
+        content   = "hello"
+        kind      = "draw",
+        drawcolor = "darkblue",
+    ] ysized h ;
+
+    draw lmt_outline [
+        content       = "hello",
+        kind          = "fill",
+        fillcolor     = "darkred",
+    ] ysized h shifted (3.75h,0) ;
+
+    draw lmt_outline [
+        content       = "hello",
+        kind          = "both",
+        fillcolor     = "darkred",
+    ] ysized h shifted (7.5h,0mm) ;
+
+    draw lmt_outline [
+        content       = "hello",
+        kind          = "both",
+        fillcolor     = "darkred",
+        drawcolor     = "darkblue",
+        rulethickness = 1/5,
+    ] ysized h shifted (0,-1.25h) ;
+
+    draw lmt_outline [
+        content       = "hello",
+        kind          = "reverse",
+        fillcolor     = "darkred",
+        drawcolor     = "darkblue",
+        rulethickness = 1/2,
+    ] ysized h shifted (3.75h,-1.25h) ;
+
+    draw lmt_outline [
+        content       = "hello",
+        kind          = "u",
+        fillcolor     = "darkgreen",
+        rulethickness = 0,
+    ] ysized h shifted (7.5h,-1.25h) ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+This interface is much nicer than the one where each variant (the parameter \type
+{kind} above) had its own macro due to the need to group properties of the
+outline and fill. Let's show some more:
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_outline [
+        content   = "\obeydiscretionaries\samplefile{tufte}",
+        align     = "normal",
+        kind      = "draw",
+        drawcolor = "darkblue",
+    ] xsized TextWidth ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_outline [
+        content   = "\obeydiscretionaries\samplefile{ward}",
+        align     = "normal,tolerant",
+        width     = 10cm,
+        kind      = "draw",
+        drawcolor = "darkblue",
+    ] xsized TextWidth ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_outline [
+        content       = "\obeydiscretionaries\samplefile{sapolsky}",
+        align         = "normal,tolerant",
+        style         = "bold",
+        width         = 10cm,
+        kind          = "draw",
+        rulethickness = 1/5,
+        drawcolor     = "darkred",
+    ] xsized TextWidth ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+Another \METAFUN\ text related mechanism deals with following a specific path.
+That interface has evolved over time, also due to more advanced possibilities in
+\MKIV. But, it's again time for a upgrade, for example:
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_followtext [
+        content = "How well does it work {\bf 1}! ",
+        path    = (fullcircle scaled 4cm),
+        trace   = true,
+        spread  = true,
+    ] ysized 5cm ;
+
+    draw lmt_followtext [
+        content = "How well does it work {\bf 2}! ",
+        path    = fullcircle scaled 4cm,
+        trace   = true,
+        spread  = false,
+        reverse = true,
+    ] ysized 5cm shifted (0,-6cm) ;
+
+    draw lmt_followtext [
+        content     = "How well does it work {\bf 3}! ",
+        trace       = true,
+        autoscaleup = "yes"
+    ] ysized 5cm shifted (6cm,0) ;
+
+    draw lmt_followtext [
+        content     = "How well does it work {\bf 4}! ",
+        path        = fullcircle scaled 2cm,
+        trace       = true,
+        autoscaleup = "max"
+    ] ysized 5cm shifted (6cm,-6cm) ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+Although \METAPOST\ can draw arrows a bit more code is involved than one would
+have expected. As a consequence, influencing the way an arrowhead is drawn as
+currently using variables is somewhat cumbersome. Here is an alternative:
+
+\startbuffer
+\startMPcode{doublefun}
+    draw lmt_arrow [
+        path = fullcircle
+            scaled  3cm
+            shifted (0,0cm),
+    ] withcolor "darkred" ;
+
+    draw lmt_arrow [
+        location = "both"
+        path     = fullcircle
+            scaled  3cm
+            rotated 90
+            shifted (0,-3.5cm),
+    ] withcolor "darkgreen" ;
+
+    draw lmt_arrow [
+        kind        = "draw",
+        location    = "middle",
+        alternative = "curved",
+        path        = fullcircle
+            scaled  3cm
+            shifted (3.5cm,0cm),
+    ] withcolor "darkblue" ;
+
+    for i = 0 step 5 until 100 :
+        draw lmt_arrow [
+            alternative = "dimpled",
+            location    = "percentage",
+            percentage  = i,
+            dimple      = (1/5 + i/200),
+            headonly    = (i = 0),
+            path        = fullcircle
+                scaled  3cm
+                shifted (3.5cm,-3.5cm),
+        ] withcolor "darkyellow" ;
+    endfor ;
+\stopMPcode
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+These new interfaces for outlines, following text and arrows certainly will make
+it in some form to be permanent \METAFUN\ extensions. Some will also be used in
+macros at the \TEX\ end, for instance, when you load the dummy library:
+
+\startbuffer
+\useMPlibrary[dum]
+\stopbuffer
+
+\typebuffer[option=TEX] \getbuffer
+
+You can do this:
+
+\startbuffer
+\startcombination
+    {\externalfigure[crap-001]} {one}
+    {\externalfigure[crap-004][alternative=triangle]} {two}
+\stopcombination
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+and get:
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+This placeholder now also can be accessed directly:
+
+\startbuffer
+\useMPmacro
+  [minifun]
+  [placeholder]
+  [width=10cm,
+   height=3cm,
+   reduction=.2,
+   alternative=triangle,
+   color=orange]
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+The \type {\useMPmacro} is an entirely new interface to \METAFUN\ code. Although
+it is still experimental, we show an example. Of course, as needed, you can throw
+in some \LUA\ magic.
+
+\startbuffer
+\startMPcalculation
+    presetparameters "demo" [
+        n = 5,
+        s = 1cm,
+    ] ;
+
+    def lmt_demo = applyparameters "demo" "lmt_do_demo" enddef ;
+
+    vardef lmt_do_demo =
+        for i=1 upto getparameter "demo" "n" :
+            draw fullcircle scaled (i*getparameter "demo" "s");
+        endfor ;
+    enddef ;
+\stopMPcalculation
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+The calculation wrapper makes this code be processed immediately, which is needed
+because we don't use a module.
+
+\getbuffer
+
+A the \TEX\ end we do this:
+
+\startbuffer
+\defineMPparameterset[demo][n=integer,s=dimension]
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\getbuffer
+
+We can now let the macro do its work:
+
+\startbuffer
+\startcombination[nx=4,location=middle]
+    {\useMPmacro[demo][n=8,s=2mm]}        {Demo 1}
+    {\useMPmacro[demo][n=4,s=4mm]}        {Demo 2}
+    {\useMPmacro[demo][n=4,s=5\exheight]} {Demo 3}
+    {\useMPmacro[demo]}                   {Demo 4}
+\stopcombination
+\stopbuffer
+
+\typebuffer[option=TEX]
+
+\startlinecorrection
+\getbuffer
+\stoplinecorrection
+
+You can also set the parameters separately. There is one catch: there is no
+grouping so in this case you need to reset the parameters afterwards.
+
+\starttyping
+\presetMPparameters[demo][n=8] \useMPmacro[demo]\blank
+\presetMPparameters[demo][n=4] \useMPmacro[demo]\blank
+\resetMPparameters [demo]      \useMPmacro[demo]\blank
+\stoptyping
+
+These examples demonstrate that we can make \METAPOST\ a bit friendlier for users
+who are not that fluent with the language. It remains to be seen to what extent
+additional modules will be written, but the possibilities are there.
+
+\stopdocument