Create a tiny library of functions (#11)

* Move functions into their own file.

* A hack to extract the result from Maxima's verbose output.

Makefile

@@ -5,4 +5,4 @@ install:
 	sudo apt-get -y install maxima maxima-share --no-install-suggests --no-install-recommends
 
 run:
-	maxima --very-quiet --batch=src/euler.mac
+	@cd src; maxima --very-quiet --batch=eulersberg.mac | grep "RESULT: "

src/euler.mac

@@ -1,5 +1,3 @@
-defstruct(graph(V, E))$
-
 path(G, P):= block(
  [result: true],
  for i: 2 step 2 thru (length(P)-1) do (
@@ -10,12 +8,4 @@ path(G, P):= block(
 
 euler_path(G, P):= (
  is(path(G, P)) and is(length(P) = 2*length(G@E) + 1)
-)$
-
-eulersberg: new(graph({A,B,C,D,E,F}, {[a,{E,F}], [b,{B,F}], [c,{B,F}], [d,{A,F}], [e,{A,F}], [f,{C,F}], [g,{A,C}], [h,{A,C}], [i,{C,D}], [k,{A,D}], [l,{D,E}], [m,{A,E}], [n,{A,E}], [o,{B,E}], [p,{A,B}]}))$
-
-s: "EaFbBcFdAeFfCgAhCiDkAmEnApBoElD"$
-
-journey: map(eval_string, charlist(s))$
-
-euler_path(eulersberg, journey);
+)$

src/eulersberg.mac

@@ -0,0 +1,11 @@
+load("euler.mac")$
+
+defstruct(graph(V, E))$
+
+eulersberg: new(graph({A,B,C,D,E,F}, {[a,{E,F}], [b,{B,F}], [c,{B,F}], [d,{A,F}], [e,{A,F}], [f,{C,F}], [g,{A,C}], [h,{A,C}], [i,{C,D}], [k,{A,D}], [l,{D,E}], [m,{A,E}], [n,{A,E}], [o,{B,E}], [p,{A,B}]}))$
+
+s: "EaFbBcFdAeFfCgAhCiDkAmEnApBoElD"$
+
+journey: map(eval_string, charlist(s))$
+
+print(concat(supcase("result: "), string(euler_path(eulersberg, journey))))$

src/maxima-init.mac

@@ -0,0 +1 @@
+showtime:all;