Why I love Metapost

I am writing some stuff about Conway’s Game of Life (and Scratch) – thinking about whether it is possible to explain to adults the basics of programming a computer using the Scratch Life script an an example: Life is more suitable for adults than say the Code Club fish chasing game and anyway it gives me an opportunity to indulge my fascination with the game.

To write the text I need to draw diagrams that explain how the rules work and I tried in both Xfig and Dia to do this. But it was a nightmare.

In contrast I could manage it very quickly in Metapost, even though the natural inclination is to steer clear of that and stick with the “point and drool” GUI based alternatives.

beginfig(1);
prologues:=3;

for i=0 upto 4:
draw (0, i*20 + 10) — (100, i*20 + 10);
draw (10 + i*20, 0) — (10 + i*20, 100);
draw (200, i*20 + 10) — (300, i*20 + 10);
draw (210 + i*20, 0) — (210 + i*20, 100);
endfor;

pickup pencircle scaled 12;
draw (140, 40) — (150, 50)–(140, 60) withcolor red;
linejoin:=mitered;

path a, b, c, d, e, f, g, h, j, k, l, m;
a = fullcircle scaled 10 shifted (40,40);
draw a;
fill a withcolor green;
b = fullcircle scaled 10 shifted (40,60);
draw b;
fill b withcolor green;
c = fullcircle scaled 10 shifted (60,60);
draw c;
fill c withcolor green;
h = fullcircle scaled 10 shifted (60,40);
draw h;
fill h withcolor green;
j = fullcircle scaled 10 shifted (40,20);
draw j;
fill j withcolor green;
k = fullcircle scaled 10 shifted (60,20);
draw k;
fill k withcolor green;

d = fullcircle scaled 10 shifted (220,40);
draw d;
fill d withcolor green;
e = fullcircle scaled 10 shifted (240,60);
draw e;
fill e withcolor green;
f = fullcircle scaled 10 shifted (260,60);
draw f;
fill f withcolor green;
g = fullcircle scaled 10 shifted (280,40);
draw g;
fill g withcolor green;
l = fullcircle scaled 10 shifted (240,20);
draw l;
fill l withcolor green;
m = fullcircle scaled 10 shifted (260,20);
draw m;
fill m withcolor green;
endfig;

Gives me this: (actually the original EPS is better as it is a vector format and the PNG won’t scale in the same way)

Metapost is not widely known and under-appreciated.

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