Data update

Task/Dragon-curve/YAMLScript/dragon-curve.ys

@@ -0,0 +1,29 @@
+!YS-v0
+
+defn main(steps=511):
+  data [minx maxx miny maxy] =:
+    loop i 0 [x y], [0 0], data {}, [minx maxx miny maxy] [0 0 0 0]:
+      dir =: i-to-dir(i)
+      nx ny =: +
+        [(x + condp(== dir 0 1 2 -1 0))
+         (y + condp(== dir 1 1 3 -1 0))]
+      ob ib =: dir.nth([[8 4][2 1][4 8][1 2]])
+      data =: update-in(data [y x] safe-bit-or ob)
+             .update-in([ny nx] safe-bit-or ib)
+      bbox =: +
+        [min(minx nx) max(maxx nx)
+         min(miny ny) max(maxy ny)]
+      if i < steps:
+        recur: i.++, [nx ny], data, bbox
+        vector: data bbox
+
+  each y (miny .. maxy):
+    say: !:join
+      each x (minx .. maxx):
+        get-in(data [y x] 0).nth(" ╵╷│╴┘┐┤╶└┌├─┴┬┼")
+
+defn i-to-dir(n):
+  n.bit-xor(bit-shift-right(n 1)):Long/bitCount % 4
+
+defn safe-bit-or(v bit):
+  (v || 0).bit-or(bit)