Put stringify fn here

index.ts

@@ -0,0 +1,24 @@
+import flatten = require("lodash.flatten");
+
+export function stringifyTree<T>(tn: T, nameFn: (t: T) => string, childrenFn: (t: T) => T[]): string {
+
+    function prefixChild(strs: string[], last: boolean): string[] {
+        return strs.map((s, i) => {
+            const prefix = i === 0 ? (last ? "└─" : "├─") : (last ? "  " : "│ ");
+            return prefix + s;
+        });
+    }
+    function nodeToStrings(tn: T): string[] {
+        const children = [...childrenFn(tn)]; // copy the array
+        if (children.length === 0) {
+            return ["─ " + nameFn(tn)];
+        }
+        return ["┬ " + nameFn(tn), ...flatten(children.map((c, i) => {
+            const strs = nodeToStrings(c);
+            return prefixChild(strs, i === (children.length - 1));
+        }))];
+    }
+
+    return nodeToStrings(tn).join("\n");
+
+}