Data commit

Task/Visualize-a-tree/F-Sharp/visualize-a-tree.fs

@@ -0,0 +1,31 @@
+type tree =
+    | T of string * tree list
+
+let prefMid = seq { yield "├─"; while true do yield "│ " }
+let prefEnd = seq { yield "└─"; while true do yield "  " }
+let prefNone = seq { while true do yield "" }
+
+let c2 x y = Seq.map2 (fun u v -> String.concat "" [u; v]) x y
+
+let rec visualize (T(label, children)) pre =
+    seq {
+        yield (Seq.head pre) + label
+        if children <> [] then
+            let preRest = Seq.skip 1 pre
+            let last = Seq.last (List.toSeq children)
+            for e in children do
+                if e = last then yield! visualize e (c2 preRest prefEnd)
+                else yield! visualize e (c2 preRest prefMid)
+    }
+
+let example =
+    T ("root",
+            [T ("a",
+                    [T ("a1",
+                            [T ("a11", []);
+                            T ("a12", []) ]) ]);
+            T ("b",
+                    [T ("b1", []) ]) ])
+
+visualize example prefNone
+|> Seq.iter (printfn "%s")