Initial data commit

Task/Universal-Turing-machine/D/universal-turing-machine-2.d

@@ -0,0 +1,18 @@
+import std.stdio, std.typecons, std.algorithm, std.string, std.array;
+
+void turing(Sy, St)(in St state, Sy[int] tape, in int pos,
+                    in Tuple!(Sy, int, St)[Sy][St] rules) {
+    if (state.empty) return;
+    const r = rules[state][tape[pos] = tape.get(pos, Sy.init)];
+    writefln("%-(%s%)", tape.keys.sort()
+        .map!(i => format(i == pos ? "(%s)" : " %s ", tape[i])));
+    tape[pos] = r[0];
+    turing(r[2], tape, pos + r[1], rules);
+}
+
+void main() {
+    turing("a", null, 0,
+           ["a": [0: tuple(1,  1, "b"), 1: tuple(1, -1, "c")],
+            "b": [0: tuple(1, -1, "a"), 1: tuple(1,  1, "b")],
+            "c": [0: tuple(1, -1, "b"), 1: tuple(1,  0, "")]]);
+}