[...] appears to scale the line by 2, [...]
When compiling Lines.hs with -O, I get
/tmp/ghc14725.hc: In function `s8Wy_ret': /tmp/ghc14725.hc:474: warning: implicit declaration of function `glScalef'
Compilation with -O makes GHC compile via the C compiler. GHC should have been told to #include <GL/gl.h> in that case, but at least for Lines.hs, it didn't do so properly. Make sure that an option like '-#include <GL/gl.h>' (glu.h or glut.h should be fine, too) gets passed to the compiler or that there is an {-# OPTIONS -#include ... #-} line at the top of that file. If the C compiler calls a function that expects a float argument without having the proper declaration, it passes a double instead, which is Not Good(tm). Not exactly a solution, but it should explain the problem... Wolfgang