Visualize a tree: Difference between revisions

=={{header|F_Sharp|F#}}==

<lang fsharp>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")</lang>

{{out}}

<pre>root

├─a

│ └─a1

│ ├─a11

│ └─a12

└─b

└─b1</pre>