Initial data commit

Task/Visualize-a-tree/Wren/visualize-a-tree.wren

@@ -0,0 +1,39 @@
+import "/dynamic" for Struct
+import "random" for Random
+
+var Stem = Struct.create("Stem", ["str", "next"])
+
+var SDOWN = "  |"
+var SLAST = "  `"
+var SNONE = "   "
+
+var rand = Random.new()
+
+var tree // recursive
+tree = Fn.new { |root, head|
+    var col = Stem.new(null, null)
+    var tail = head
+    while (tail) {
+        System.write(tail.str)
+        if (!tail.next) break
+        tail = tail.next
+    }
+    System.print("--%(root)")
+    if (root <= 1) return
+    if (tail && tail.str == SLAST) tail.str = SNONE
+    if (!tail) {
+        tail = head = col
+    } else {
+        tail.next = col
+    }
+    while (root != 0) { // make a tree by doing something random
+        var r = 1 + rand.int(root)
+        root = root - r
+        col.str = (root != 0) ? SDOWN : SLAST
+        tree.call(r, head)
+    }
+    tail.next = null
+}
+
+var n = 8
+tree.call(n, null)