// Rules
dup(a1,a2) >< (int i):xs => a1~(i:xs1), a2~(i:xs2), dup(xs1,xs2)~xs;
dup(a1,a2) >< []         => a1~[], a2~[];

inc(r) >< (int i):xs => r~(i+1):w, inc(w)~xs;
inc(r) >< []         => r~[];


// Nets
dup(r,w)~r1, inc(r1) ~ (0:w);

//       +-----+       +-----+        +---+
// r ----|     |  r1   |     |        |   |
//       | dup |--->---| inc |---><---| 0 |----+
//   +---|     |       |     |        |   |    |
//   |   +-----+       +-----+        +---+    |
//   |                                         |
//   +-----------------------------------------+
//             w