From 0d14e5623d3d5fac4dd3485939c0c5ea9d62abba Mon Sep 17 00:00:00 2001
From: Matthijs Kooijman <matthijs@stdin.nl>
Date: Tue, 6 Oct 2009 10:36:49 +0200
Subject: [PATCH] Use a dotted lines to separate context in a transformation.

---
 Utils/Lambda.tex | 19 +++++++++++++++++++
 pret-lam.lua     |  2 +-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/Utils/Lambda.tex b/Utils/Lambda.tex
index 1128c46..f1952ea 100644
--- a/Utils/Lambda.tex
+++ b/Utils/Lambda.tex
@@ -22,6 +22,25 @@ draw b;
   {\setupMPvariables[HLine][#1]%
   \useMPgraphic{HLine}}
 
+\startuseMPgraphic{HDLine}
+path a, b;
+% Create a rectangle of the full size
+a := origin -- (\MPvar{width}, 0mm);
+% Randomize it a bit
+b := a randomized (\overlaywidth / 100) ;
+% And draw it
+drawoptions (withpen pencircle scaled .75mm withcolor black dashed evenly) ;
+draw b; 
+\stopuseMPgraphic
+
+% Draw a line with the given options. Accepts only the 'width' option. Be
+% careful that these are metapost options, so use \the\textwidth instead of
+% textwidth, and a metapost expression for arithmethic (e.g. 0.5 *
+% \the\textwidth instead of 0.5\textwidth).
+\def\HDLine[#1]%
+  {\setupMPvariables[HDLine][#1]%
+  \useMPgraphic{HDLine}}
+
 \startuseMPgraphic{box}
 path a, b;
 % Create a rectangle of the full size
diff --git a/pret-lam.lua b/pret-lam.lua
index 7058f62..568da7f 100644
--- a/pret-lam.lua
+++ b/pret-lam.lua
@@ -23,7 +23,7 @@ local symbols = {
     -- The default * sits very high above the baseline, \ast (u+2217) looks
     -- better.
     ['*'] = {repr = '\\ast'},
-    ['~'] = {repr = '\\sim'},
+    ['~'] = {repr = '\\HDLine[width=.20 * \\the\\textwidth]'},
     ['|'] = {repr = '\\char' .. utf.byte('|')},
 }
 
-- 
2.30.2