Show LED numbers.

lednumbers.fsx

open System

let ledNums = [
    [" _ "; "| |"; "|_|"]
    ["   "; "  |"; "  |"]
    [" _ "; " _|"; "|_ "]
    [" _ "; " _|"; " _|"]
    ["   "; "|_|"; "  |"]
    [" _ "; "|_ "; " _|"]
    [" _ "; " _|"; "|_|"]
    [" _ "; "  |"; "  |"]
    [" _ "; "|_|"; "|_|"]
    [" _ "; "|_|"; "  |"]]

let parse c =
    let result, num = Int32.TryParse(c.ToString())
    match result with
    | true -> Some(num)
    | false -> None

while true do
    Console.Write("input number: ")
    let nums = Console.ReadLine()
               |> Seq.choose(parse)
    [0..2]
    |> List.fold(fun acc i ->
            let line = nums |> Seq.fold(fun l n -> l + ledNums.[n].[i]) ""
            acc + line + Environment.NewLine
       ) ""
    |> printfn "%s"