open System
open System.IO

let countLines path wildcard recurse =
    
    let lineCount file = 

        let isEmpty (line : string) = line.Trim() = ""
        let isComment (line : string) = line.Trim().StartsWith("//")
        let isCode (line : string) = not (isEmpty line) && not (isComment line)

        File.ReadAllLines file 
        |> Seq.filter (fun line -> isCode line) 
        |> Seq.length

    Directory.EnumerateFiles(path, wildcard, if recurse then SearchOption.AllDirectories else SearchOption.TopDirectoryOnly)
    |> Seq.map (fun file -> lineCount file )
    |> Seq.sum

// Example
let test1 =
    countLines @"D:\FSExperience\FSExperience" "*.fs" false

let test2 =
    countLines @"D:\FSExperience" "*.fs" true